INDEX TO FORM 10‑K

1

PART I

Forward‑Looking Statements

The following discussion should be read in conjunction with our accompanying Consolidated Financial Statements and Notes thereto included within this Annual Report on Form 10‑K. In addition to historical information, this Annual Report on Form 10‑K and the following discussion contain statements that are not historical facts and are considered forward‑looking within the meaning of Section 27A of the Securities Act and Section 21E of the Exchange Act. These forward‑looking statements contain projections of our future results of operations or of our financial position or state other forward‑looking information. In some cases you can identify these statements by forward‑looking words such as “anticipate,” “believe,” “could,” “continue,” “estimate,” “expect,” “intend,” “may,” “should,” “will,” “would,” “plan,” “projected” or the negative of such words or other similar words or phrases. We believe that it is important to communicate our future expectations to our investors. However, there may be events in the future that we are filingnot able to accurately predict or control and that may cause our actual results to differ materially from the expectations we describe in our forward‑looking statements. Investors are cautioned not to unduly rely on forward‑looking statements because they involve risks and uncertainties, and actual results may differ materially from those discussed as a result of various factors, including, but not limited to: the risk that we continue to incur losses and anticipate continuing to incur losses; the risk that we will need to raise additional capital to fund our operations and such capital may not be available to us; our ability to obtain financing arrangements to support the sale or leasing of our products and services to customers; the ability to achieve the forecasted gross margin on the sale of our products; the volatility of our stock price; the risk that a sale of a significant number of shares of stock could depress the market price of our common stock; the risk that a loss of one or more of our major customers could result in a material adverse effect on our financial condition; the cost and availability of fuel and fueling infrastructures for our products; the risk of elimination of government subsidies and economic incentives for alternative energy products; the risk of potential losses related to any product liability claims or contract disputes; competitive factors, such as price competition and competition from other traditional and alternative energy companies; the cost and availability of components and parts for our products; our ability to establish and maintain relationships with third parties with respect to product development, manufacturing, distribution and servicing and the supply of key product components;  the risk that pending orders may not convert to purchase orders, in whole or in part; the risk that unit orders will not ship, be installed and/or converted to revenue, in whole or in part; the risks related to the use of flammable fuels in our products; our ability to protect our intellectual property; the risk that our lack of extensive experience in manufacturing and marketing products may impact our ability to manufacture and market products on a profitable and large‑scale commercial basis; the cost and timing of developing, marketing and selling our products and our ability to raise the necessary capital to fund such costs; market acceptance of our products and services, including GenDrive units; our ability to develop commercially viable products; our ability to reduce product and manufacturing costs; our ability to successfully market, distribute and service our products and services internationally; our ability to improve system reliability for our products; the risk of loss related to an inability to maintain an effective system of internal controls; our ability to attract and maintain key personnel;   the risks associated with potential future acquisitions; the cost of complying with current and future federal, state and international governmental regulations; and other risks and uncertainties discussed under Item IA—Risk Factors. Readers should not place undue reliance on our forward‑looking statements. These forward‑looking statements speak only as of the date on which the statements were made and are not guarantees of future performance. Except as may be required by applicable law, we do not undertake or intend to update any forward‑looking statements after the date of this Annual Report on Form 10‑K.

Item 1.  Business

Background

Plug Power Inc., or the Company, is a leading provider of alternative energy technology focused on the design, development, commercialization and manufacture of hydrogen and fuel cell systems used primarily for the material handling and stationary power markets.  As part of the global drive to electrification, Plug Power has recently entered new electric vehicle markets, specifically ground support equipment and electric delivery vans. These applications promote the advancement of hydrogen fueling and accelerate commercialization of hydrogen-fueled products.

   We are focused on proton exchange membrane, or PEM, fuel cell and fuel processing technologies, fuel cell/battery hybrid technologies, and associated hydrogen storage and dispensing infrastructure from which multiple products are available. A fuel cell is an electrochemical device that combines hydrogen and oxygen to produce electricity and heat without combustion. Hydrogen is derived from hydrocarbon fuels such as liquid petroleum gas, or LPG, natural

gas, propane, methanol, ethanol, gasoline or biofuels. Plug Power develops complete hydrogen generation, delivery, storage and refueling solutions for customer locations. Currently the Company obtains the majority of its hydrogen by purchasing it from fuel suppliers for resale to customers.

In our core business, we provide and continue to develop commercially-viable hydrogen and fuel cell product solutions to replace lead‑acid batteries in electric material handling vehicles and industrial trucks for some of the world’s largest distribution and manufacturing businesses. We are focusing our efforts on industrial mobility applications (electric forklifts and electric industrial vehicles) at multi‑shift high volume manufacturing and high throughput distribution sites where our products and services provide a unique combination of productivity, flexibility and environmental benefits. Additionally, we manufacture and sell fuel cell products to replace batteries and diesel generators in stationary backup power applications. These products prove valuable with telecommunications, transportation and utility customers as robust, reliable and sustainable power solutions. 

We were organized as a corporation in the State of Delaware on June 27, 1997.

Unless the context indicates otherwise, the terms “Company,” “Plug Power,” “we,” “our” or “us” as used herein refers to Plug Power Inc. and its subsidiaries.

Business Strategy

We are committed to developing effective, economical and reliable fuel cell related products, systems and services for businesses and government agencies. Building on our substantial fuel cell application and product integration experience, we are focused on generating strong relationships with customers who value increased reliability, productivity and energy security.

Our business strategy leverages our unique fuel cell application and integration knowledge to identify early adopter markets for which we can design and develop innovative systems and customer solutions that provide superior value, ease‑of‑use and environmental design.

Our primary marketing strategy is to focus our resources on the material handling market. Through established customer relationships, Plug Power has proven itself as a trusted partner with a reliable fuel cell solution.  We have made significant progress in penetrating the material handling market, supported through the deployment of over 20,000 GenDrive units into commercial applications. We believe we have developed reliable products which allow the end customers to eliminate incumbent power sources from their operations, and realize their sustainability objectives through clean energy alternatives. In addition, we have deployed our GenKey hydrogen and fuel cell solution to multiple customer sites.

Our operating strategy also includes the following objectives: decrease product and service costs, expand system reliability, improve service and post‑sales support experience.

Our longer‑term objectives are to deliver economic, social, and environmental benefits in terms of reliable, clean, cost‑effective fuel cell solutions and, ultimately, productivity.

We believe continued investment in research and development is critical to the development and enhancement of innovative products, technologies and services. In addition to evolving our direct hydrogen fueled systems, we continue to capitalize on our investment and expertise in power electronics, controls, and software design.

We continue to develop and monitor future fuel cell solutions that align with our evolving product roadmap. By leveraging our current GenDrive architecture, Plug Power is evaluating adjacent markets such as ProGen electric vehicles, ground support equipment (GSE) and fuel cell vehicles.

Business Organization

We manage our business as a single operating segment, emphasizing shared learning across end‑user applications and common supplier/vendor relationships.

Products and Services

In our core business, we provide and continue to develop commercially-viable hydrogen and fuel cell product solutions to replace lead‑acid batteries in electric material handling vehicles and industrial trucks for some of the world’s largest distribution and manufacturing businesses. We are focusing our efforts on industrial mobility applications (electric forklifts and electric industrial vehicles) at multi‑shift high volume manufacturing and high throughput distribution sites where our products and services provide a unique combination of productivity, flexibility and environmental benefits. Additionally, we manufacture and sell fuel cell products to replace batteries and diesel generators in stationary backup power applications. These products prove valuable with telecommunications, transportation and utility customers as robust, reliable and sustainable power solutions. 

Our current products and services include:

GenDrive: GenDrive is our hydrogen fueled PEM fuel cell system providing power to material handling electric vehicles, including class 1, 2, 3 and 6 electric forklifts and ground support equipment;

GenFuel:  GenFuel is our hydrogen fueling delivery, generation, storage and dispensing systems;

GenCare: GenCare is our ongoing maintenance program for GenDrive fuel cells, GenSure products, GenFuel products and ProGen engines;

GenSure:   GenSure is our stationary fuel cell solution providing scalable, modular PEM fuel cell power to support the backup and grid-support power requirements of the telecommunications, transportation, and utility sectors;

GenKey: GenKey is our turn-key solution combining either GenDrive or GenSure power with GenFuel fuel and GenCare aftermarket service, offering complete simplicity to customers transitioning to fuel cell power;

ProGen:  ProGen is our fuel cell stack and engine technology currently used globally in mobility and stationary fuel cell systems, and as engines in electric delivery vans; and

GenFund: GenFund is a collaboration with leasing organizations to provide cost efficient and seamless financing solutions to customers.

Plug Power provides our products worldwide through our direct product sales force, and by leveraging relationships with original equipment manufacturers, or OEMs, and their dealer networks.

To promote fuel cell adoption and maintain post‑sale customer satisfaction, we offer a range of service and support options through extended maintenance contracts. Additionally, customers may waive our service option, and choose to service their systems independently. A high percentage of fuel cells sold in recent years were bundled with maintenance contracts. As a result, only 1% of fuel cells deployed are still under standard warranty that is not a part of an extended maintenance contract.

Markets/Geography & Order Status

The Company’s products and services predominantly serve the North American and European material handling markets, and primarily support large to mid-sized fleet, multi‑shift operations in high‑volume manufacturing and high‑throughput distribution centers. Based on recent market experience, it appears there may be some seasonality to sales stemming from varied customer appropriation cycles; however, these market factors will continue to evolve and the Company’s insight to these trends will improve with continued commercial success and time.

Orders for the Company’s products and services in 2017 approximated $285.0 million compared to total orders in 2016 of $280.0 million. The Company’s backlog for products and services as of December 31, 2017 was in excess of $500.0 million, compared to the Company’s backlog as of December 31, 2016 of approximately $380.0 million. The Company’s backlog at any given time is comprised of products, hydrogen installations, maintenance services, and hydrogen fuel deliveries. The specific elements of the backlog will vary in terms of timing of delivery and can vary between 90 days to 10 years, with products and hydrogen installations being delivered near term and maintenance services and

hydrogen fuel deliveries being delivered over a longer period of time. Historically, shipments made against these product orders generally occur between ninety days and twenty‑four months from the date of acceptance of the order.

For the year ended December 31, 2017,  71.8% of total consolidated revenues were associated primarily with Amazon and Walmart, representing 42.4% and 29.4%, respectively. A loss or decline in business with either customer could have an adverse impact on our business, financial condition and results of operations.

We assemble our products at our manufacturing facilities in Latham, New York and Spokane, Washington, and provide our services and installations at customer locations. Currently, the supply and manufacture of varied critical components used in our products and services are performed by sole‑sourced third‑party vendors in the U.S., Canada and China.

Distribution, Marketing and Strategic Relationships

We have developed strategic relationships with well‑established companies in key areas including distribution, service, marketing, supply, technology development and product development. We sell our products worldwide, with a primary focus on North America, through our direct product sales force, original equipment manufacturers, or OEMs, and their dealer networks. Additionally, we operate in Europe under the name HyPulsion, to develop and sell hydrogen fuel cell systems for the European material handling market.

Competition

We are confronted by competition in all areas of our business. The markets we address for motive power are characterized by the presence of well‑established battery and combustion generator products. The principal competitive factors in the markets in which we operate include product features, including size and weight, relative price and performance, product quality and reliability, design innovation, marketing and distribution capability, service and support and corporate reputation.

In the material handling market, we believe our GenDrive products have an advantage over lead‑acid batteries for customers who run high‑throughput distribution centers and manufacturing locations with multi‑shift operations by offering increased productivity with lower operational costs. However, we expect competition in this space to intensify as competitors attempt to imitate our approach with their own offerings.

Intellectual Property

We believe that neither we nor our competitors can achieve a significant proprietary position on the basic technologies currently used in PEM fuel cell systems. However, we believe the design and integration of our system and system components, as well as some of the low‑cost manufacturing processes that we have developed, are intellectual property that can be protected. Our intellectual property portfolio covers among other things: fuel cell components that reduce manufacturing part count; fuel cell system designs that lend themselves to mass manufacturing; improvements to fuel cell system efficiency, reliability and system life; and control strategies, such as added safety protections and operation under extreme conditions. In general, our employees are party to agreements providing that all inventions, whether patented or not, made or conceived while being our employee, which are related to or result from work or research that we perform, will remain our sole and exclusive property.

We have a total of 134 issued patents currently active with the USPTO. At the close of 2017, we had four U.S. patent applications pending. Additionally, we have 20 trademarks registered with the USPTO and three trademark applications pending.

Government Regulation

Our products and their installations are subject to oversight and regulation at the state and local level in accordance with state and local statutes and ordinances relating to, among others, building codes, fire codes, public safety, electrical and gas pipeline connections and hydrogen siting. The level of regulation may depend, in part, upon where a system is located.

In addition, product safety standards have been established by the American National Standards Institute, or ANSI, covering the overall fuel cell system. The class 1, 2 and 3 GenDrive products are designed with the intent of meeting the requirements of UL 2267 “Fuel Cell Power Systems for Installation in Industrial Electric Trucks” and NFPA 505 “Fire Safety Standard for Powered Industrial Trucks”. The hydrogen tanks used in these systems have been either certified to ANSI/CSA NGV2‑2007 “Compressed Natural Gas Vehicle Fuel Containers” or ISO/TS 15869 “Gaseous hydrogen and hydrogen blends—Land vehicle fuel tanks”. We will continue to design our GenDrive products to meet ANSI and/or other standards in 2017. We certified several models of Class 1, 2 and 3 GenDrive products to the requirements of the CE mark with guidance from a European certified body. The hydrogen tanks used in these systems are certified to the Pressure Equipment Directive by a European certified body.

The GenFuel hydrogen storage and dispensing products are designed with the intent of meeting the requirements of NFPA 2 “Hydrogen Technologies Code”.

Other than these requirements, at this time we do not know what additional requirements, if any, each jurisdiction will impose on our products or their installation. We also do not know the extent to which any new regulations may impact our ability to distribute, install and service our products. As we continue distributing our systems to our target markets, the federal, state, local or foreign government entities may seek to impose regulations or competitors may seek to influence regulations through lobbying efforts.

Raw Materials and Suppliers

Most components essential to our business are generally available from multiple sources.  We believe there are component suppliers and manufacturing vendors whose loss to us could have a material adverse effect upon our business and financial condition. We are mitigating these potential risks by introducing alternate system architectures which we expect will allow us to diversify our supply chain with multiple fuel cell stack and air supply component vendors. We are also working closely with these vendors and other key suppliers on coordinated product introduction plans, strategic inventories, and internal and external manufacturing schedules and levels.

Research and Development

Because the fuel cell industry is characterized by its early state of adoption, our ability to compete successfully is heavily dependent upon our ability to ensure a continual and timely flow of competitive products, services, and technologies to the marketplace. We continue to develop new products and technologies and to enhance existing products in the areas of cost, size, weight, and in supporting service solutions in order to drive further commercialization.

We may expand the range of our product offerings and intellectual property through licensing and/or acquisition of third‑party business and technology. Our research and development expense totaled $28.7 million, $21.2 million, and $14.9 million during the years ended December 31, 2017, 2016 and 2015, respectively. We also had cost of research and development contract revenue of $0.3, $0.9 million, $0.5 and million during the years ended December 31, 2017, 2016 and 2015, respectively. These expenses represent the cost of research and development programs that are partially funded under cost reimbursement research and development arrangements with third parties and are reported within other cost of revenue on the consolidated statements of operations.

Employees

As of December 31, 2017, we had 644 employees, including 108 temporary employees. We consider our relationship with our employees to be positive.

Financial Information About Geographic Areas

Please refer to our Geographic Information included in our Consolidated Financial Statements and notes thereto included in Part II, Item 8: Financial Statements and Supplementary Data of this Form 10-K/A10‑K.

Available Information

Our Annual Report on Form 10‑K, Quarterly Reports on Form 10‑Q, Current Reports on Form 8‑K and amendments to providethose reports filed or furnished pursuant to Section 13(a) or 15(d) of the Exchange Act are available free

of charge, other than an investor’s own internet access charges, on the Company’s website with an internet address of www.plugpower.com as soon as reasonably practicable after the Company electronically files such material with, or furnishes it to the Securities and Exchange Commission (SEC). The information contained on our website is not included as a part of, or incorporated by reference into, this Annual Report on Form 10‑K. The public may read and copy any materials the Company files with the SEC at the SEC’s Public Reference Room at 100 F Street, N.E., Washington, DC 20549. The public may also obtain information on the operation of the Public Reference Room by calling the SEC at 1‑800‑SEC‑0330. The SEC also maintains an internet site that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC. The SEC’s website address is http://www.sec.gov.

Item 1A.  Risk Factors

The following risk factors should be considered carefully in addition to the other information in this Annual Report on Form 10‑K. The occurrence of any of the following material risks could harm our business and future results of operations and could result in the trading price of our common stock declining and a partial or complete loss of your investment. These risks are not the only ones that we face. Additional risks not presently known to us or that we currently consider immaterial may also impair our business operations and trading price of our common stock. Except as mentioned under “Quantitative and Qualitative Disclosure About Market Risk” and except for the historical information contained herein, the discussion contained in this Annual Report on Form 10‑K contains “forward‑looking statements,” within the required time period.meaning of Section 27A of the Securities Act and Section 21E of the Exchange Act, that involve risks and uncertainties. Please refer to the section entitled “Forward‑Looking Statements.”

We have incurred losses and anticipate continuing to incur losses.

We have not achieved operating profitability in any quarter since our formation and we will continue to incur net losses until we can produce sufficient revenue to cover our costs. Our net losses were approximately $127.1 million in 2017, $57.5 million in 2016, $55.7 million in 2015, $88.5 million in 2014, and $62.7 million in 2013. As of December 31, 2017, we had an accumulated deficit of $1.2 billion. We anticipate that we will continue to incur losses until we can produce and sell our products on a large‑scale and cost‑effective basis. We cannot guarantee when we will operate profitably, if ever. In order to achieve profitability, we must successfully execute our planned path to profitability in the early adoption markets on which we are focused. The hydrogen infrastructure that is needed to support our growth readiness and cost efficiency must be available and cost efficient. We must continue to shorten the cycles in our product roadmap with respect to improvement in product reliability and performance that our customers expect. We must execute on successful introduction of our products into the market. We must accurately evaluate our markets for, and react to, competitive threats in both other technologies (such as advanced batteries) and our technology field. Finally, we must continue to lower our products’ build costs and lifetime service costs. If we are unable to successfully take these steps, we may never operate profitably, and, even if we do achieve profitability, we may be unable to sustain or increase our profitability in the future.

In addition, Item 15the primary current value proposition for our customers stems from productivity gains in using our solutions. Longer term, given evolving market dynamics and changes in alternative energy tax credits, if we are unable to successfully develop future products that are competitive with competing technologies in terms of Part IVprice, reliability and longevity, customers may not buy our products. The profitability of our products depends largely on material and manufacturing costs and the market price of hydrogen. We cannot guarantee that we will be able to lower these costs to the levels to assure market acceptance in conjunction with other critical customer criteria in performance and reliability.

We may require additional capital funding and such capital may not be available to us.

On December 31, 2017, we had cash and cash equivalents of $24.8 million, restricted cash of $43.2 million and net working capital of $3.9 million. This compares to $46.0 million, $54.6 million and $44.4 million, respectively, on December 31, 2016. Restricted cash becomes available to us as we perform in accordance with the related leasing agreements.

Our cash requirements relate primarily to working capital needed to operate and grow our business, including funding operating expenses, growth in inventory to support both shipments of new units and servicing the installed base, growth in equipment leased to customers under long-term arrangements, funding the growth in our GenKey “turn-key” solution, which includes the installation of our customers’ hydrogen infrastructure as well as delivery of the hydrogen fuel,  continued expansion of our markets, such as Europe and China, continued development and expansion of our products,

such as Pro Gen, payment of lease obligations under sale/leaseback financings, and the repayment or refinancing of our long-term debt. Our ability to achieve profitability and meet future liquidity needs and capital requirements will depend upon numerous factors, including the timing and quantity of product orders and shipments; attaining and expanding positive gross margins across all product lines; the timing and amount of our operating expenses; the timing and costs of working capital needs; the timing and costs of building a sales base; the ability of our customers to obtain financing to support commercial transactions; our ability to obtain financing arrangements to support the sale or leasing of our products and services to customers, including financing arrangements to repay or refinance our long-term debt, and the terms of such agreements that may require us to pledge or restrict substantial amounts of our cash to support these financing arrangements; the timing and costs of developing marketing and distribution channels; the timing and costs of product service requirements; the timing and costs of hiring and training product staff; the extent to which our products gain market acceptance; the timing and costs of product development and introductions; the extent of our ongoing and new research and development programs; and changes in our strategy or our planned activities. If we are unable to fund our operations with positive cash flows and cannot obtain external financing, we may not be able to sustain future operations.  As a result, we may be required to delay, reduce and/or cease our operations and/or seek bankruptcy protection.

We cannot assure you that any necessary additional financing will be available on terms favorable to us, or at all. We believe that it could be difficult to raise additional funds and there can be no assurance as to the availability of additional financing or the terms upon which additional financing may be available. Additionally, even if we raise sufficient capital through additional equity or debt financings, strategic alternatives or otherwise, there can be no assurance that the revenue or capital infusion will be sufficient to enable us to develop our business to a level where it will be profitable or generate positive cash flow. If we raise additional funds through the issuance of equity or convertible debt securities, the percentage ownership of our stockholders could be significantly diluted, and these newly issued securities may have rights, preferences or privileges senior to those of existing stockholders. If we incur additional debt, a substantial portion of our operating cash flow may be dedicated to the payment of principal and interest on such indebtedness, thus limiting funds available for our business activities. The terms of any debt securities issued could also impose significant restrictions on our operations. Broad market and industry factors may seriously harm the market price of our common stock, regardless of our operating performance, and may adversely impact our ability to raise additional funds. If we raise additional funds through collaborations and/or licensing arrangements, we might be required to relinquish significant rights to our technologies, or grant licenses on terms that are not favorable to us.

If we cannot obtain financing to support the sale or leasing of our products and services to customers, such failure may adversely affect our sales, profitability and liquidity.

Customers representing most of our revenue lease, rather than purchase, our products. These lease arrangements require us to finance the purchase of such products, either ourselves or through third‑party financing sources. For example, approximately $42.2 million of our cash is currently restricted to support such leasing arrangements, which prevents us from using such cash for other purposes. To date, we have been successful in obtaining or providing the necessary financing arrangements. There is no certainty, however, that we will be able to continue to obtain or provide adequate financing for these arrangements on acceptable terms, or at all, in the future. Failure to obtain or provide such financing may result in the loss of material customers and product sales, which could have a material adverse effect on our business, financial condition and results of operations. Further, if we are required to continue to pledge or restrict substantial amounts of our cash to support these financing arrangements, such cash will not be available to us for other purposes, which may have a material adverse effect on our liquidity and financial position.

Our stock price and stock trading volume has been solely amendedand could remain volatile.

The market price of our common stock has historically experienced and may continue to experience significant volatility. In 2017, the sales price of our common stock fluctuated from a high of $3.21 per share to a low of $0.83 per share. Our progress in developing and commercializing our products, our quarterly operating results, announcements of new products by us or our competitors, our perceived prospects, changes in securities’ analysts’ recommendations or earnings estimates, changes in general conditions in the economy or the financial markets, adverse events related to our strategic relationships, significant sales of our common stock by existing stockholders, including one or more of our strategic partners, and other developments affecting us or our competitors could cause the market price of our common stock to fluctuate substantially. In addition, in recent years, the stock market has experienced significant price and volume fluctuations. This volatility has affected the market prices of securities issued by many companies for reasons unrelated to their operating performance and may adversely affect the price of our common stock. Such market price volatility could adversely affect our ability to raise additional capital. In addition, we may be subject to additional securities class action

litigation as a result of volatility in the price of our common stock, which could result in substantial costs and diversion of management’s attention and resources and could harm our stock price, business, prospects, results of operations and financial condition.

Sales of a substantial number of shares of our common stock in the public market could occur at any time. These sales, or the market perception that the holders of a large number of shares intend to sell shares, could reduce the market price of our common stock.

Additionally, market conditions may result in volatility in the level of, and fluctuations in, the market prices of stocks generally and, in turn, our common stock and sales of substantial amounts of our common stock in the market, in each case being unrelated or disproportionate to changes in our operating performance.

We depend on a concentration of anchor customers for the majority of our revenues and the loss of any of these customers would adversely affect our business, financial condition, results of operations and cash flows.

We sell most of our products to a range of customers that include new certificationsa few anchor customers, and while we are continually seeking to expand our customer base, we expect this will continue for the next several years.  For example, for the year ended December 31, 2017, 71.8% of total consolidated revenues were associated primarily with Amazon and Walmart, representing 42.4% and 29.4%, respectively. For the years ended December 31, 2016 and 2015, 34.1% and 56.7%, respectively, of total consolidated revenues were associated primarily with Walmart.  Any decline in business with significant customers could have an adverse impact on our business, financial condition and results of operations. Our future success is dependent upon the continued purchases of our products by a small number of customers.  If we are unable to broaden our customer base and expand relationships with potential customers, our business will continue to be impacted by demand fluctuations due to our dependence on a small number of customers. Demand fluctuations can have a negative impact on our revenues, business, financial condition, results of operations and cash flows. Our dependence on a small number of major customers exposes us to additional risks.  A slowdown, delay or reduction in a customer’s orders could result in excess inventories or unexpected quarterly fluctuations in our operating results and liquidity.  Each of our major customers has significant purchasing leverage over us to require changes in sales terms including pricing, payment terms and product delivery schedules, which could adversely affect our business, financial condition, results of operations and cash flows.  If one of our major customers delays payment of or is unable to pay their receivables, that could have a material adverse effect on our business, financial condition, results of operations and cash flows.

Our product sales and performance depends on the availability of hydrogen.

Our products and services depend largely on the availability of hydrogen gas. We are dependent upon hydrogen suppliers for success with the profitable commercialization of our products and services. Although we will continue to work with hydrogen suppliers to mutually agree on terms for our customers, including, but not limited to, the competitiveness of the price of the hydrogen fuel, liquid hydrogen, hydrogen infrastructure and service costs, to the benefit of our product value proposition, ultimately we have no control over such third parties. If these fuels are not readily available or if their prices are such that energy produced by our products costs more than energy provided by other sources, then our products could be less attractive to potential users and our products’ value proposition could be negatively affected. If hydrogen suppliers elect not to participate in the material handling market, there may be an insufficient supply of hydrogen for this market that could negatively affect our sales and deployment of our products and services.

Delays in or not completing our product development goals may adversely affect our revenue and profitability

If we experience delays in meeting our development goals, our products exhibit technical defects, or if we are unable to meet cost or performance goals, including power output, useful life and reliability, the profitable commercialization of our products will be delayed. In this event, potential purchasers of our products may choose alternative technologies and any delays could allow potential competitors to gain market advantages. We cannot assure that we will successfully meet our commercialization schedule in the future.

Periodically, we may enter into contracts with our customers for certain products that have not been developed or produced. There can be no assurance that we will complete the development of these products and meet the specifications required to fulfill customer agreements and deliver products on schedule. Pursuant to such agreements, the customers would have the right to provide notice to us if, in their good faith judgment, we have materially deviated from

such agreements. Should a customer provide such notice, and we cannot mutually agree to a modification to the agreement, then the customer may have the right to terminate the agreement, which could adversely affect our future business.

Other than our current products, which we believe to be commercially viable at this time, we do not know when or whether we will successfully complete research and development of other commercially viable products that could be critical to our future. If we are unable to develop additional commercially viable products, we may not be able to generate sufficient revenue to become profitable. The profitable commercialization of our products depends on our ability to reduce the costs of our components and subsystems, and we cannot assure you that we will be able to sufficiently reduce these costs. In addition, the profitable commercialization of our products requires achievement and verification of their overall reliability, efficiency and safety targets, and we cannot assure you that we will be able to develop, acquire or license the technology necessary to achieve these targets. We must complete additional research and development to fill our product portfolios and deliver enhanced functionality and reliability in order to manufacture additional commercially viable products in commercial quantities. In addition, while we are conducting tests to predict the overall life of our products, we may not have run our products over their projected useful life prior to large‑scale commercialization. As a result, we cannot be sure that our products will last as long as predicted, resulting in possible warranty claims and commercial failures.

The reduction or elimination of government subsidies and economic incentives for alternative energy technologies, or the failure to renew such subsidies and incentives could reduce demand for our products.

We believe that the near‑term growth of alternative energy technologies is affected by the availability and size of government and economic incentives. Many of these government incentives expire, phase out over time, may exhaust the allocated funding, or require renewal by the applicable authority. In addition, these incentive programs could be reduced or discontinued for other reasons. The investment tax credit under the U.S. tax code was renewed in February 2018 and is scheduled to expire December 31, 2022.  The renewal allows for a 30% investment tax credit which begins to phase out from 2020 to 2022. The reduction, elimination, or expiration of the investment tax credit or other government subsidies and economic incentives, or the failure to renew such tax credit, governmental subsidies, or economic incentives, may result in the diminished economic competitiveness of our products to our customers and could materially and adversely affect the growth of alternative energy technologies, including our products, as well as our future operating results and liquidity.

Certain component quality issues have resulted in adjustments to our warranty reserves and the accrual for loss contracts.

In the past, quality issues have arisen with respect to certain components in certain products that are currently being used at customer sites. Under the terms of our extended maintenance contracts, we have had to retrofit units subject to component quality issues with replacement components that will improve the reliability of our products for our customers. We recorded a provision for loss contracts related to service in prior years. Though, we continue to work with our vendors on these component issues to improve quality and reliability,  unanticipated additional quality issues or warranty claims may arise and, additional material charges may be incurred in the future.  Quality issues also could cause profitable maintenance contracts to become unprofitable.

In addition, from time to time we experience other unexpected design or product performance issues. We make significant investment in the continued improvement of our products and maintains appropriate warranty reserves for known and unexpected issues; however, unknown malfunctions or design defects could result in unexpected material liabilities and could adversely affect our business, financial condition, results of operation, cash flows and prospects. In addition, a well‑publicized actual or perceived problem could adversely affect the market’s perception of our products resulting in a decline in demand for our products and could divert the attention of our management, which may materially and adversely affect our business, financial condition, results of operations, cash flows and prospects.

Our products and services face intense competition.

The markets for energy products are intensely competitive. Some of our competitors in the motive power sector (predominantly incumbent technologies) are much larger than we are and may have the manufacturing, marketing and sales capabilities to complete research, development and commercialization of profitable, commercially viable products more quickly and effectively than we can. There are many companies engaged in all areas of traditional and alternative energy generation in the United States and abroad, including, among others, major electric, oil, chemical, natural gas, battery, generator and specialized electronics firms, as well as universities, research institutions and foreign

government‑sponsored companies. These firms are engaged in forms of power generation such as advanced battery technologies, generator sets, fast charged technologies and other types of fuel cell technologies. Technological advances in alternative energy products, battery systems or other fuel cell technologies may make our products less attractive or render them obsolete.

A material change in cost,  performance, availability, or development of key suppliers’ products could have a material adverse effect on our business.

We have certain key suppliers who we rely on for critical components in our products, and there are numerous other components for our products that are sole sourced. A supplier’s failure to develop and supply components in a timely manner or at all, or to develop or supply components that meet our quality, quantity or cost requirements, or our inability to obtain substitute sources of these components on a timely basis or on terms acceptable to us, could harm our ability to manufacture our products. In addition, to the extent that our supply partners use technology or manufacturing processes that are proprietary, we may be unable to obtain comparable components from alternative sources.

In addition, commodity prices and supply levels affect our costs. For example, platinum is a key material in our PEM fuel cells. Platinum is a scarce natural resource and we are dependent upon a sufficient supply of this commodity. Any shortages could adversely affect our ability to produce commercially viable fuel cell systems and significantly raise our cost of producing our fuel cell systems. While we do not anticipate significant near‑ or long‑term shortages in the supply of platinum, a shortage could adversely affect our ability to produce commercially viable PEM fuel cells or raise our cost of producing such products.

We may be unable to establish or maintain relationships with third parties for certain aspects of continued product development, manufacturing, distribution and servicing and the supply of key components for our products.

We may also need to maintain and may need to enter into additional strategic relationships in order to complete our current product development and commercialization plans. We may also require partners to assist in the sale, servicing and supply of components for our current products and anticipated products, which are in development. If we are unable to identify, enter into, and maintain satisfactory agreements with potential partners, including those relating to the supply, distribution, service and support of our current products and anticipated products, we may not be able to complete our product development and commercialization plans on schedule or at all. We may also need to scale back these plans in the absence of needed partners, which could adversely affect our future prospects for development and commercialization of future products. While we have entered into relationships with suppliers of some key components for our products, we do not know when or whether we will secure supply relationships for all required components and subsystems for our products, or whether such relationships will be on terms that will allow us to achieve our objectives. Our business prospects, results of operations and financial condition could be harmed if we fail to secure relationships with entities that can develop or supply the required components for our products and provide the required distribution and servicing support. Additionally, the agreements governing our current relationships allow for termination by our partners under certain circumstances, some of which are beyond our control. If any of our current strategic partners were to terminate any of its agreements with us, there could be a material adverse impact on the continued development and profitable commercialization of our products and the operation of our business, financial condition, results of operations and prospects.

Our purchase orders may not ship, be commissioned or installed, or convert to revenue.

Some of the orders we accept from customers require certain conditions or contingencies to be satisfied, or may be cancelled, prior to shipment or prior to commissioning or installation, some of which are outside of our control. Historically, shipments made against these orders have generally occurred between ninety days and twenty‑four months from the date of acceptance of the order. Orders for the Company’s products and services in 2017 approximated $285.0 million compared to total orders in 2016 of $280.0 million. The Company’s backlog for products and services as of December 31, 2017 was in excess of $500.0 million, compared to the Company’s backlog as of December 31, 2016 of approximately $380.0 million. The time periods from receipt of an order to shipment date and installation vary widely and are determined by a number of factors, including the terms of the customer contract and the customer’s deployment plan. There may also be product redesign or modification requirements that must be satisfied prior to shipment of units under certain of our agreements. If the redesigns or modifications are not completed, some or all of our orders may not ship or convert to revenue. We publicly disclose anticipated, pending orders with prospective customers; however, those prospective customers may require certain conditions or contingencies to be satisfied prior to issuing a purchase order to

us, some of which are outside of our control. Such conditions or contingencies that may be required to be satisfied before we receive a purchase order may include, but are not limited to, successful product demonstrations or field trials. Converting orders into revenue is also dependent upon our customers’ ability to obtain financing. Some conditions or contingencies that are out of our control may include, but are not limited to, government tax policy, government funding programs, and government incentive programs. Additionally, some conditions and contingencies may extend for several years. We may have to compensate customers, by either reimbursement, forfeiting portions of associated revenue, or other methods depending on the terms of the customer contract, based on the failure on any of these conditions or contingencies. While not probable, this could have an adverse impact on our revenue and cash flow.

We are dependent on information technology in our operations and the failure of such technology may adversely affect our business.

We may experience problems with the operation of our current information technology systems or the technology systems of third parties on which we rely, as well as the development and deployment of new information technology systems, that could adversely affect, or even temporarily disrupt, all or a portion of our operations until resolved. Inabilities and delays in implementing new systems can also affect our ability to realize projected or expected cost savings. Despite the implementation of network security measures, our information technology could be penetrated by outside parties (such as computer hackers or cyber terrorists) intent on extracting information, corrupting information or disrupting business processes. Such unauthorized access could disrupt our business and could result in a loss of assets or reputational damage. Additionally, any systems failures could impede our ability to timely collect and report financial results in accordance with applicable laws.

Our products use flammable fuels that are inherently dangerous substances.

Our fuel cell systems use hydrogen gas in catalytic reactions. While our products do not use this fuel in a combustion process, hydrogen gas is a flammable fuel that could leak and combust if ignited by another source. Further, while we are not aware of any significant accidents involving our products, any such accidents involving our products or other products using similar flammable fuels could materially suppress demand for, or heighten regulatory scrutiny of, our products.

The risk of product liability claims and associated adverse publicity is inherent in the development, manufacturing, marketing and sale of fuel cell products, including products fueled by hydrogen, a flammable gas. Any liability for damages resulting from malfunctions or design defects could be substantial and could materially adversely affect our business, financial condition, results of operations and prospects. In addition, an actual or perceived problem could adversely affect the market’s perception of our products resulting in a decline in demand for our products, which may materially and adversely affect our business, financial condition, results of operations and prospects.

We are subject to legal proceedings and legal compliance risks that could harm our business.

From time to time, we may be subject to contract disputes or litigation. In connection with any disputes or litigation in which we are involved, we may incur costs and expenses in connection with defending ourselves or in connection with the payment of any settlement or judgment or compliance with any ruling in connection therewith if there is an unfavorable outcome. The expense of defending litigation may be significant. The amount of time to resolve lawsuits is unpredictable and defending ourselves may divert management’s attention from the day‑to‑day operations of our business, which could adversely affect our business, financial condition, results of operations and cash flows. In addition, an unfavorable outcome in any such litigation could have a material adverse effect on our business, results of operations, financial condition and cash flows.

We may not be able to protect important intellectual property and we could incur substantial costs defending against claims that our products infringe on the proprietary rights of others.

PEM fuel cell technology was first developed in the 1950s, and fuel processing technology has been practiced on a large scale in the petrochemical industry for decades. Accordingly, we do not believe that we can establish a significant proprietary position in the fundamental component technologies in these areas. However, our ability to compete effectively will depend, in part, on our ability to protect our proprietary system‑level technologies, systems designs and manufacturing processes. We rely on patents, trademarks, and other policies and procedures related to confidentiality to protect our intellectual property. However, some of our intellectual property is not covered by any patent or patent application.

Moreover, we do not know whether any of our pending patent applications will issue or, in the case of patents issued or to be issued, that the claims allowed are or will be sufficiently broad to protect our technology or processes. Even if all of our patent applications are issued and are sufficiently broad, our patents may be challenged or invalidated. We could incur substantial costs in prosecuting or defending patent infringement suits or otherwise protecting our intellectual property rights. While we have attempted to safeguard and maintain our proprietary rights, we do not know whether we have been or will be completely successful in doing so. Moreover, patent applications filed in foreign countries may be subject to laws, rules and procedures that are substantially different from those of the United States, and any resulting foreign patents may be difficult and expensive to obtain and enforce. In addition, we do not know whether the U.S. Patent & Trademark Office will grant federal registrations based on our pending trademark applications. Even if federal registrations are granted to us, our trademark rights may be challenged. It is also possible that our competitors or others will adopt trademarks similar to ours, thus impeding our ability to build brand identity and possibly leading to customer confusion. We could incur substantial costs in prosecuting or defending trademark infringement suits.

Further, our competitors may independently develop or patent technologies or processes that are substantially equivalent or superior to ours. If we are found to be infringing third party patents, we could be required to pay substantial royalties and/or damages, and we do not know whether we will be able to obtain licenses to use such patents on acceptable terms, if at all. Failure to obtain needed licenses could delay or prevent the development, manufacture or sale of our products, and could necessitate the expenditure of significant resources to develop or acquire non‑infringing intellectual property.

We may need to pursue lawsuits or legal action in the future to enforce our intellectual property rights, to protect our trade secrets and domain names, and to determine the validity and scope of the proprietary rights of others. If third parties prepare and file applications for trademarks used or registered by us, we may oppose those applications and be required to participate in proceedings to determine the priority of rights to the trademark. Similarly, competitors may have filed applications for patents, may have received patents and may obtain additional patents and proprietary rights relating to products or technology that block or compete with ours. We may have to participate in interference proceedings to determine the priority of invention and the right to a patent for the technology. Litigation and interference proceedings, even if they are successful, are expensive to pursue and time consuming, and we could use a substantial amount of our management and financial resources in either case.

Confidentiality agreements to which we are party may be breached, and we may not have adequate remedies for any breach. Our trade secrets may also be known without breach of such agreements or may be independently developed by competitors. Our inability to maintain the proprietary nature of our technology and processes could allow our competitors to limit or eliminate any competitive advantages we may have.

We face risks associated with our plans to market, distribute and service our products and services internationally.

We have begun to market, distribute, sell and service our product offerings internationally. We have limited experience operating internationally, including developing and manufacturing our products to comply with the commercial and legal requirements of international markets. Our success in international markets will depend, in part, on our ability and that of our partners to secure relationships with foreign sub‑distributors, and our ability to manufacture products that meet foreign regulatory and commercial requirements. Additionally, our planned international operations are subject to other inherent risks, including potential difficulties in enforcing contractual obligations and intellectual property rights in foreign countries and fluctuations in currency exchange rates. Also, to the extent our operations and assets are located in foreign countries, they are potentially subject to nationalization actions over which we will have no control.

For example, we operate in France under the name HyPulsion to develop and sell hydrogen fuel cell systems for the European material handling market. However, for the reasons discussed above, HyPulsion may not be able to accomplish its goals or become profitable.

Doing business in foreign markets requires us to be able to respond to rapid changes in market, legal, and political conditions in these countries. As we expand in international markets, we may face numerous challenges, including unexpected changes in regulatory requirements, potential conflicts or disputes that countries may have to deal with, fluctuations in currency exchange rates, longer accounts receivable requirements and collections, difficulties in managing international operations, potentially adverse tax consequences, restrictions on repatriation of earnings and the burdens of complying with a wide variety of international laws. Any of these factors could adversely affect our results of operations

and financial condition. The success of our international expansion will depend, in part, on our ability to succeed in differing legal, regulatory, economic, social and political environments.

If we fail to maintain an effective system of internal controls, we may not be able to accurately report our financial results or prevent fraud.

Effective internal controls over financial reporting are necessary for us to provide reliable and accurate financial reports and effectively prevent fraud. We have devoted significant resources and time to comply with the internal control over financial reporting requirements of the Sarbanes‑Oxley Act of 2002. In addition, Section 404 under the Sarbanes‑Oxley Act of 2002 requires that we assess the design and operating effectiveness of our controls over financial reporting. We are currently required to have our auditors attest to the effectiveness of our internal control over financial reporting. Our compliance with the annual internal control report requirement will depend on the effectiveness of our financial reporting and data systems and controls. Inferior internal controls increase the possibility of errors and could cause investors to lose confidence in our reported financial information, which could have a negative effect on the trading price of our stock and our access to capital.

In addition, our internal control systems rely on people trained in the execution of the controls. Loss of these people or our inability to replace them with similarly skilled and trained individuals or new processes in a timely manner could adversely impact our internal control mechanisms.

Our future plans could be harmed if we are unable to attract or retain key personnel.

We have attracted a highly skilled management team and specialized workforce, including scientists, engineers, researchers, manufacturing, marketing and sales professionals. Our future success will depend, in part, on our ability to attract and retain qualified management and technical personnel. We do not know whether we will be successful in hiring or retaining qualified personnel. Our inability to hire qualified personnel on a timely basis, or the departure of key employees, could materially and adversely affect our development and profitable commercialization plans and, therefore, our business prospects, results of operations and financial condition.

Potential future acquisitions could be difficult to integrate, divert the attention of key personnel, disrupt our business and impair our financial results.

As part of our business strategy, we intend to consider acquisitions of companies, technologies and products. Acquisitions, involve numerous risks, any of which could harm our business, including, difficulty in integrating the technologies, products, operations and existing contracts of a target company and realizing the anticipated benefits of the combined businesses; difficulty in supporting and transitioning customers, if any, of the target company; inability to achieve anticipated synergies or increase the revenue and profit of the acquired business; potential disruption of our ongoing business and distraction of management; the price we pay or other resources that we devote may exceed the value we realize; or the value we could have realized if we had allocated the purchase price or other resources to another opportunity and inability to generate sufficient revenue to offset acquisition costs. In addition, if we finance acquisitions by issuing equity securities, our existing stockholders may be diluted. As a result, if we fail to properly evaluate acquisitions or investments, we may not achieve the anticipated benefits of any such acquisitions, and we may incur costs in excess of what we anticipate.

Our business may become subject to increased government regulation.

Our products are subject to certain federal, local, and non‑U.S. laws and regulations, including, for example, state and local ordinances relating to building codes, public safety, electrical and gas pipeline connections, hydrogen transportation and siting and related matters. See “Business—Government Regulations” for additional information. Further, as products are introduced into the market commercially, governments may impose new regulations. We do not know the extent to which any such regulations may impact our ability to manufacture, distribute, install and service our products. Any regulation of our products, whether at the federal, state, local or foreign level, including any regulations relating to the production, operation, installation, and servicing of our products may increase our costs and the price of our products.

Provisions in our charter documents and Delaware law may discourage or delay an acquisition of the Company by a third party that stockholders may consider favorable.

Our certificate of incorporation, our bylaws, and Delaware corporate law contain provisions that could make it harder for a third party to acquire us without the consent of our board of directors. These provisions include those that: authorize the issuance of up to 5,000,000 shares of preferred stock in one or more series without a stockholder vote; limit stockholders’ ability to call special meetings; establish advance notice requirements for nominations for election to our board of directors or for proposing matters that can be acted on by stockholders at stockholder meetings; and provide for staggered terms for our directors. We have a shareholders rights plan that may be triggered if a person or group of affiliated or associated persons acquires beneficial ownership of 15% or more of the outstanding shares of our common stock. In addition, in certain circumstances, Delaware law also imposes restrictions on mergers and other business combinations between us and any holder of 15% or more of our outstanding common stock.

Item 1B.  Unresolved Staff Comments

There are no unresolved comments regarding our periodic or current reports from the staff of the SEC that were issued 180 days or more preceding the end of our year ended December 31, 2017.

Item 2.  Properties

Our principal executive officeroffices are located in Latham, New York, where we lease a 140,000 square foot facility that includes our headquarter office building, our manufacturing facility, and our research and development center. In addition, we lease a 29,200 square foot facility in Spokane, Washington that includes an office building and a manufacturing facility. We also lease service centers in Dayton, Ohio and Romeoville, Illinois. See Note 17, Commitments and Contingencies of the Consolidated Financial Statements, Part II, Item 8 of this Form 10‑K for further discussion of the leases. We believe that our facilities are sufficient to accommodate our anticipated production volumes for at least the next two years.

Item 3.  Legal Proceedings

An action has been brought in New York State Supreme Court by General Electric Co. (GE) and an affiliate against the Company seeking $1 million that GE claims is due under an indemnification agreement between GE and the Company. GE seeks indemnification for funds it paid to settle a claim with Soroof Trading Development Co., an entity that had paid funds to GE to become a distributor of the Company’s products. The Company is vigorously defending the action.

Item 4.  Mine Safety Disclosures

Not applicable.

PART II

Item 5.  Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities

Market Information.  Our common stock is traded on the NASDAQ Capital Market under the symbol “PLUG.” As of March 6, 2018, there were approximately 621 record holders of our common stock. However, management believes that a significant number of shares are held by brokers under a “nominee name” and that the number of beneficial shareholders of our common stock exceeds 110,180. The following table sets forth the high and low sale price per share of our common stock as reported by the NASDAQ Capital Market for the periods indicated:

Dividend Policy.  We have never declared or paid cash dividends on our common stock and do not anticipate paying cash dividends in the foreseeable future. Any future determination as to the payment of dividends will depend upon capital requirements and limitations imposed by our credit agreements, if any, and such other factors as our board of directors may consider.

Five‑Year Performance Graph.  Below is a line graph comparing the percentage change in the cumulative total return of the Company’s common stock, based on the market price of the Company’s common stock, with the total return of companies included within the NASDAQ Clean Edge Green Energy Index (CELS) and the companies included within the Russell 2000 Index (RUT) for the period commencing December 31, 2012 and ending December 31, 2017. The calculation of the cumulative total return assumes a $100 investment in the Company’s common stock, the NASDAQ Clean Edge Green Energy Index (CELS) and the Russell 2000 Index (RUT) Index on December 31, 2012 and the reinvestment of all dividends, if any.

See also Part III Item 12 in this Annual Report on Form 10‑K for additional detail related to security ownership and related stockholder matters, and for additional detail on equity compensation plan matters.

Item 6.  Selected Financial Data

The following tables set forth selected financial data and other operating information of the Company. The selected statement of operations and balance sheet data for 2017, 2016, 2015, 2014, and 2013, as set forth below are derived from the audited Consolidated Financial Statements of the Company. The information is only a summary and you should read it in conjunction with the Company’s audited Consolidated Financial Statements and related notes and other financial information included herein and “Management’s Discussion and Analysis of Financial Condition and Results of Operations.”

Item 7.  Management’s Discussion and Analysis of Financial Condition and Results of Operations

The discussion contained in this Form 10‑K contains “forward‑looking statements,” within the meaning of Section 27A of the Securities Act and Section 21E of the Exchange Act, that involve risks and uncertainties. Our actual results could differ materially from those discussed in this Form 10‑K. In evaluating these statements, you should review

Part I, Item 1A: Risk Factors and our Consolidated Financial Statements and notes thereto included in Part II, Item 8: Financial Statements and Supplementary Data of this Form 10‑K.

Overview

Plug Power Inc., or the Company, is a leading provider of alternative energy technology focused on the design, development, commercialization and manufacture of hydrogen and fuel cell systems used primarily for the material handling and stationary power markets.  As part of the global drive to electrification, Plug Power has recently entered new electric vehicle markets, specifically ground support equipment and electric delivery vans. These applications promote the advancement of hydrogen fueling and accelerate commercialization of hydrogen-fueled products.

We are focused on proton exchange membrane, or PEM, fuel cell and fuel processing technologies, fuel cell/battery hybrid technologies, and associated hydrogen storage and dispensing infrastructure from which multiple products are available. A fuel cell is an electrochemical device that combines hydrogen and oxygen to produce electricity and heat without combustion. Hydrogen is derived from hydrocarbon fuels such as liquid petroleum gas, or LPG, natural gas, propane, methanol, ethanol, gasoline or biofuels. Plug Power develops complete hydrogen generation, delivery, storage and refueling solutions for customer locations. Currently the Company obtains the majority of its hydrogen by purchasing it from fuel suppliers for resale to customers.

In our core business, we provide and continue to develop commercially-viable hydrogen and fuel cell product solutions to replace lead‑acid batteries in electric material handling vehicles and industrial trucks for some of the world’s largest distribution and manufacturing businesses. We are focusing our efforts on industrial mobility applications (electric forklifts and electric industrial vehicles) at multi‑shift high volume manufacturing and high throughput distribution sites where our products and services provide a unique combination of productivity, flexibility and environmental benefits. Additionally, we manufacture and sell fuel cell products to replace batteries and diesel generators in stationary backup power applications. These products prove valuable with telecommunications, transportation and utility customers as robust, reliable and sustainable power solutions. Plug Power provides our products worldwide through our direct product sales force, and by leveraging relationships with original equipment manufacturers, or OEMs, and their dealer networks.

Our current products and services include:

GenDrive: GenDrive is our hydrogen fueled PEM fuel cell system providing power to material handling electric vehicles, including class 1, 2, 3 and 6 electric forklifts and ground support equipment;

GenFuel:  GenFuel is our hydrogen fueling delivery, generation, storage and dispensing systems;

GenCare: GenCare is our ongoing maintenance program for GenDrive fuel cells, GenSure products, GenFuel products and ProGen engines;

GenSure:  GenSure is our stationary fuel cell solution providing scalable, modular PEM fuel cell power to support the backup and grid-support power requirements of the telecommunications, transportation, and utility sectors;

GenKey: GenKey is our turn-key solution combining either GenDrive or GenSure power with GenFuel fuel and GenCare aftermarket service, offering complete simplicity to customers transitioning to fuel cell power;

ProGen:  ProGen is our fuel cell stack and engine technology currently used globally in mobility and stationary fuel cell systems, and as engines in electric delivery vans; and

GenFund: GenFund is a collaboration with leasing organizations to provide cost efficient and seamless financing solutions to customers.

We provide our products worldwide through our direct product sales force, and by leveraging relationships with original equipment manufacturers, or OEMs, and their dealer networks.

Results of Operations

Revenue, cost of revenue, gross (loss)/profit and gross margin for the years ended December 31, 2017, 2016, and 2015, was as follows (in thousands):

Our primary sources of revenue are from sales of fuel cell systems and related infrastructure, services performed on fuel cell systems and related infrastructure, Power Purchase Agreements (PPAs), and fuel delivered to customers.  Revenue from sales of fuel cell systems and related infrastructure represents sales of our GenDrive units, GenSure stationary backup power units, as well as hydrogen fueling infrastructure. Revenue from services performed on fuel cell systems and related infrastructure represents revenue earned on our service and maintenance contracts and sales of spare parts.  Revenue from PPAs primarily represents payments received from customers who make monthly payments to access the Company’s GenKey solution.  Revenue associated with fuel delivered to customers represents the sale of hydrogen to customers that has been purchased by the Company from a third party.

Revenue –sales of fuel cell systems and related infrastructure. Revenue from sales of fuel cell systems and related infrastructure represents revenue from the sale of our fuel cells, such as GenDrive units and GenSure stationary backup power units, as well as hydrogen fueling infrastructure referred to at the site level as hydrogen installations.

Revenue from sales of fuel cell systems and related infrastructure for the year ended December 31, 2017 increased $31.3 million, or 78.3%, to $71.3 million from $40.0 million for the year ended December 31, 2016.  The main driver for the increased revenue was an increase in GenDrive deployment volume and infrastructure site increases, as well as pricing mix. There were 3,293 units recognized as revenue during the year ended December 31, 2017, compared to 1,383 for the year ended December 31, 2016. An additional 1,785 units were shipped in 2017 and held as leased assets. As such, the Company will recognize revenue on these units over the life of the related PPA under “Power Purchase Agreements” in the Consolidated Statement of Operations. Ten hydrogen installations occurred during the year ended December 31, 2017, for which the Company recognized revenue.  In addition, seven additional sites were constructed and held as leased assets. There were seven hydrogen installations for the year ended December 31, 2016, for which the Company recognized

revenue.  In addition, 11 additional sites were constructed and held as leased property during the year ended December 31, 2016.

Revenue from sales of fuel cell systems and related infrastructure for the year ended December 31, 2016 decreased $38.0 million, or 48.7%, to $40.0 million from $78.0 million for the year ended December 31, 2015. The Company recognized revenue on 1,383 GenDrive units during the year ended December 31, 2016, as compared to 3,634 during the year ended December 31, 2015.  An additional 2,605 units were deployed in 2016 and held as leased property because they were associated with sale/leaseback transactions accounted for as capital leases. Due to the growing PPA installed base, the Company will generate higher levels of revenue under “Power Purchase Agreements” in future periods. GenDrive units shipped in 2016 were predominantly associated with the GenKey solution. Revenue was also recognized for hydrogen installations at seven sites in 2016, compared to 18 sites in 2015. An additional 11 sites were deployed in 2016 and held as leased property. 

Revenue – services performed on fuel cell systems and related infrastructure.  Revenue from services performed on fuel cell systems and related infrastructure represents revenue earned on our service and maintenance contracts and sales of spare parts.  At December 31, 2017, there were 11,296 fuel cell units and 40 hydrogen installations under extended maintenance contracts, an increase from 8,950 and 8,655 fuel cell units and 30 and 23 hydrogen installations at December 31, 2016 and 2015, respectively.

Revenue from services performed on fuel cell systems and related infrastructure for the year ended December 31, 2017 increased $2.3 million, or 11.3%, to $22.8 million from $20.5 million for the year ended December 31, 2016. The increase in service revenues was due to the increase in units under service contracts. The revenue increase was not as significant as the increase in number of units under service contracts mainly due to deployments that occurred later in 2017 and, therefore, did not earn or only partially earned service revenue for 2017 as well as the occurrence of slightly less billable incidents and nonrecurring revenue. The average number of units under extended maintenance contracts in 2017 was 9,889, compared to 8,933 in 2016. This 10.7% increase in average units serviced throughout the year is corresponding with the increase in revenue, as compared to the prior years.

Revenue from services performed on fuel cell systems and related infrastructure for the year ended December 31, 2016 increased $6.4 million, or 46.0%, to $20.5 million from $14.0 million for the year ended December 31, 2015. The increase in this revenue category is primarily related to the Company’s increase in sales of fuel cell systems and hydrogen installations in recent years, which has had a corresponding impact on the installed base.  The average number of units under extended maintenance contracts in 2016 was 8,933, compared to 6,986 in 2015. This 27.8% increase in average units serviced throughout the year is corresponding with the increase in revenue, as compared to the prior years.  The extent of the revenue increase, as compared to the unit increase, is due to improved customer pricing mix. 

Revenue – Power Purchase Agreements.  Revenue from PPAs represents payments received from customers for power generated through the provision of equipment and service.  The equipment and service can be associated with sale/leaseback transactions in which the Company sells fuel cell systems and related infrastructure to a third-party, leases them back and operates them at customers’ locations who are parties to PPAs with the Company.  Alternatively, the Company can retain the equipment as leased property and provide it to customers under PPAs.  At December 31, 2017, there were 33 GenKey sites associated with PPAs, as compared to 25 at December 31, 2016 and 14 at December 31, 2015.

Revenue from Power Purchase Agreements for the year ended December 31, 2017 increased $6.6 million, or 48.2%, to $20.3 million from $13.7 million for the year ended December 31, 2016. The increase is due to the increased number of sites the Company has deployed with these types of arrangements. The average number of sites under PPA arrangements was 30 in 2017, as compared to 21 in 2016.

Revenue from Power Purchase Agreements for the year ended December 31, 2016 increased $8.0 million or 139.4%, to $13.7 million from $5.7 million for the year ended December 31, 2015. The increase is due to the increased numbers of sites the Company has deployed with these types of arrangements. The average number of sites under PPA arrangements was 21 in 2016, as compared to 10 in 2015.

Revenue – fuel delivered to customers.  Revenue associated with fuel delivered to customers represents the sale of hydrogen to customers that has been purchased by the Company from a third party.  As part of the GenKey solution, the Company contracts with fuel suppliers to purchase liquid hydrogen, which is then sold to its customers.  At December 31, 2017, there were 58 sites associated with fuel contracts, as compared to 40 at December 31, 2016 and 22 at December

31, 2015.  The sites generally are the same as those which had purchased hydrogen installations within the GenKey solution.

Revenue associated with fuel delivered to customers for the year ended December 31, 2017 increased $7.4 million, or 67.7%, to $18.3 million from $10.9 million for the year ended December 31, 2016. The increase in revenue is due to an increase of sites taking fuel deliveries in 2017, compared to 2016.  The average number of sites receiving fuel deliveries was 50 in 2017, as compared to 33 in 2016.

Revenue associated with fuel delivered to customers for the year ended December 31, 2016 increased $5.8 million, or 115.1%, to $10.9 million from $5.1 million for the year ended December 31, 2015. The increase in revenue is due to an increase of 18 additional sites taking fuel deliveries in 2016, compared to 2015. The average number of sites receiving fuel deliveries was 33 in 2016, as compared to 14 in 2015.

Revenue  –other.  Other revenue primarily represents cost reimbursement research and development contracts associated with the development of PEM fuel cell technology. We generally share in the cost of these programs with our cost‑sharing percentages ranging from 30% to 50% of total project costs. Revenue from time and material contracts is recognized on the basis of hours expended plus other reimbursable contract costs incurred during the period. We expect to continue certain research and development contract work that is related to our current product development efforts. Other miscellaneous revenue is recognized from time to time.

Other revenue for the year ended December 31, 2017 decreased $0.6 million, or 67.9%, to $0.3 million from $0.9 million for the year ended December 31, 2016. During the year ended December 31, 2017, the Company’s other revenue was associated with a research & development project with the European Union. The Company had no revenue associated with a customer stack development program, which resulted in $0.4 million of revenue for the year ended December 31, 2016.

Other revenue for the year ended December 31, 2016 increased $0.4 million, or 83.8%, to $0.9 million from $0.5 million for the year ended December 31, 2015. During 2016, the Company recorded $0.4 million in technology access fees from a customer related to stacks being developed internally as compared to $0.1 million for the year ended December 31, 2015. The Company has also been working on a U.S. government-related research and development project as it did in prior years, and had research & development activities related to a European Union related contract.

Revenue – provision for common stock warrants.  In 2017, in separate transactions, the Company issued to each of Amazon.com, Inc. (“Amazon”) and  Wal-Mart Stores, Inc. (“Walmart”) warrants to purchase shares of the Company’s common stock.  The Company records a portion of the estimated fair value of the warrants as a reduction of revenue based upon the projected number of shares of common stock expected to vest under the warrants, theproportion of purchases by Amazon, Walmart and their affiliates within the period relative to the aggregate purchase levels required for vesting of the respective warrants, and the then-current fair value of the warrants. The amount of provision for common stock warrants recorded as a reduction of revenue during the year ended December 31, 2017 was $17.3 million for Amazon and $12.4 million for Walmart.

Cost of revenue – sales of fuel cell systems and related infrastructure.  Cost of revenue from sales of fuel cell systems and related infrastructure includes direct materials, labor costs, and allocated overhead costs related to the manufacture of our fuel cells such as GenDrive units and GenSure stationary backup power units, as well as hydrogen fueling infrastructure referred to at the site level as hydrogen installations.

Cost of revenue from sales of fuel cell systems and related infrastructure for the year ended December 31, 2017 increased 85.5%, or $25.3 million, compared to the year ended December 31, 2016, driven by the previously stated greater number of units recognized as revenue. Gross margin generated from sales of fuel cell systems and related infrastructure was 23.1% for the year ended December 31, 2017, down from 26.1% for the year ended December 31, 2016, due to product and site mix changes as well as expediting costs associated with a significant ramp up of production volume related to acquiring a large customer account that required higher deployments during the year ended December 31, 2017 compared to the same period in 2016.

Cost of revenue from sales of fuel cell systems and related infrastructure for the year ended December 31, 2016 decreased $38.2 million, or (56.4%), to $29.5 million from $67.7 million for the year ended December 31, 2015. Gross margin generated from sales of fuel cell systems and related infrastructure was 26.1% in 2016 and 13.2% in 2015. Costs

per unit have increased due to product mix, however revenue and gross margin have benefited from the more favorable pricing mix. 

Cost of revenue – services performed on fuel cell systems and related infrastructure. Cost of revenue from services performed on fuel cell systems and related infrastructure includes the labor, material costs and allocated overhead costs incurred for our product service and hydrogen site maintenance contracts and spare parts.  At December 31, 2017, there were 11,296 fuel cell units and 40 hydrogen installations under extended maintenance contracts, compared to 8,950 and 30 at December 31, 2016 and 8,655 and 23 at December 2015, respectively.  

Cost of revenue from services performed on fuel cell systems and related infrastructure for the year ended December 31, 2017 increased 4.1%, or $0.9 million, to $23.6 million, compared to the year ended December 31, 2016 of $22.6 million.  Gross margin improved to (3.5%) for the year ended December 31, 2017 from (10.7%) for the year ended December 31, 2016.  The change versus the prior year is due to a reduction in costs resulting from changes in product configuration rolled out to new key accounts and leverage of the existing fixed costs in the field.

Cost of revenue from services performed on fuel cell systems and related infrastructure for the year ended December 31, 2016 decreased $0.3 million, or (1.3%), to $22.6 million from $22.9 million for the year ended December 31, 2015. The decrease in the cost is attributed to increasing reliability of new units and replacement parts in the field offset by a growing installed base of GenDrive units and serviceable infrastructure sites.  Gross margin improved to (10.7%) in 2016 from (63.7%) in 2015 to also due better reliability of new units and replacement parts. Not impacting gross margin is approximately $8.2 million of parts, labor and overhead costs that was absorbed by the accrual for loss contracts related to service.

Cost of revenue—provision for loss contracts related to service.  During 2015, the Company recognized a $10.1 million provision for loss contracts related to service. This provision represented extended maintenance contracts that had projected costs over the remaining life of the contracts that exceeded contractual revenues.  During the year ended December 31, 2016, the Company renegotiated one of its service contracts and replaced 96 of the older fuel cell systems in service at that particular customer.  As a result, the projected costs over the remaining life of the amended contract were estimated to be reduced as compared to the previous estimate, resulting in a lower necessary accrual.  The change in estimate was recorded as a gain within cost of revenue where the original charge was recorded. 

Cost of revenue – Power Purchase Agreements.  Cost of revenue from PPAs includes payments made to financial institutions for leased equipment and service used to fulfill the PPAs, and depreciation of leased property.  Leased units are primarily associated with sale/leaseback transactions in which the Company sells fuel cell systems and related infrastructure to a third-party, leases them back, and operates them at customers’ locations who are parties to PPAs with the Company.  Alternatively, the Company can hold the equipment for investment and recognize the depreciation and service cost of the assets as cost of revenue from PPAs.  At December 31, 2017, there were 33 GenKey sites associated with PPAs, as compared to 25 at December 31, 2016 and 14 at December 31, 2015. 

Cost of revenue from Power Purchase Agreements for the year ended December 31, 2017 increased $14.5 million, or 90.0%, to $30.6 million from $16.1 million for the year ended December 31, 2016. The increase was a result of the increase in the number of customer sites party to these agreements. Gross margin declined to (51.1%) for the year ended December 31, 2017 from (17.9%) for the year ended December 31, 2016, due primarily to an increase in the number of sites accounted for as capital leases (which include depreciation of capitalized leased asset costs and maintenance costs), compared to operating leases.

Cost of revenue from Power Purchase Agreements for the year ended December 31, 2016 increased $10.9 million, or 207.1%, to $16.1 million from $5.3 million for the year ended December 31, 2015. The increase was a result of the increase in the number of customer sites covered by these agreements. Gross margin declined to (17.9) % in 2016 from 8.1% in 2015, due primarily to changes in financing pricing, depreciation of capitalized leased asset costs related to sites constructed in 2016 associated with capital leases, as well as costs to maintain them.

Cost of revenue – fuel delivered to customers.  Cost of revenue from fuel delivered to customers represents the purchase of hydrogen from suppliers that ultimately is sold to customers.  As part of the GenKey solution, the Company contracts with fuel suppliers to purchase liquid hydrogen and separately sells to its customers upon delivery.  At December 31, 2017, there were 58 sites associated with fuel contracts, as compared to 40 at December 31, 2016 and 22 at December 31, 2015.  The sites generally are the same as those which had purchased hydrogen installations within the GenKey solution.

Cost of revenue from fuel delivered to customers for the year ended December 31, 2017 increased $8.1 million, or 58.8%, to $22.0 million from $13.9 million for the year ended December 31, 2016.  The increase is due primarily to higher volume of liquid hydrogen delivered to customer sites as a result of an increase in the number of hydrogen installations completed under GenKey agreements and higher fuel costs.  Gross margin percent improved to (20.3%) during the year ended December 31, 2017 compared to (27.0%) during the year ended December 31, 2016 due to improvements in efficiencies from changes in system design.

Cost of revenue from fuel delivered to customers for the year ended December 31, 2016 increased $7.2 million, or 107.1%, to $13.9 million from $6.7 million for the year ended December 31, 2015. The increase is due to higher cost of fuel per kilogram in 2016, as compared to 2015, and a greater volume delivered to customer sites, as a result of an increase in the number of hydrogen installations completed under GenKey agreements. Gross margin improved to (27.0%) in 2016 from (31.9%) in 2015, due primarily to a settlement of a claim with a gas supplier, and improved efficiencies in fuel usage.

Cost of revenue – other.  Other cost of revenue primarily represents costs associated with research and development contracts including: cash and non-cash compensation and benefits for engineering and related support staff, fees paid to outside suppliers for subcontracted components and services, fees paid to consultants for services provided, materials and supplies used and other directly allocable general overhead costs allocated to specific research and development contracts.

Cost of other revenue for the year ended December 31, 2017 decreased $0.6 million, or 64.4%, to $0.3 million from $0.9 million for the year ended December 31, 2016.  The Company had no costs associated with a customer stack development program as it did in the year ended December 31, 2016. The entire cost of other revenue in the period is related to the research & development project with the European Union.

Cost of other revenue for the year ended December 31, 2016 increased $0.3 million, or 60.2%, to $0.9 million from $0.5 million for the year ended December 31, 2015. The Company has been working on a U.S. government‑related research and development project, as it did in prior years, and had research & development activities in a European Union related contract.

Research and development expense. Research and development expense includes: materials to build development and prototype units, cash and non-cash compensation and benefits for the engineering and related staff, expenses for contract engineers, fees paid to consultants for services provided, materials and supplies consumed, facility related costs such as computer and network services, and other general overhead costs associated with our research and development activities.

Research and development expense for the year ended December 31, 2017 increased $7.5 million, or 35.5% to $28.7 million, from $21.2 million for the year ended December 31, 2016.  This increase was primarily related to an increase in development of ProGen, and personnel related expenses from higher headcount, focused on refinement of hydrogen infrastructure design, multiple product cost-down programs and prototyping for stack performance enhancement.

Research and development expense for the year ended December 31, 2016 increased $6.2 million, or 41.7%, to $21.2 million from $14.9 million for the year ended December 31, 2015. This increase was primarily related to an increase in personnel related expenses from higher headcount, focused on refinement of hydrogen infrastructure design, multiple product cost-down programs and prototyping for stack performance enhancement.  Additional increases are due to higher levels of fuel and materials consumed on hydrogen infrastructure development.

Selling, general and administrative expenses.  Selling, general and administrative expenses includes cash and non-cash compensation, benefits, amortization of intangible assets, and related costs in support of our general corporate functions, including general management, finance and accounting, human resources, selling and marketing, information technology and legal services.

Selling, general and administrative expenses for the year ended December 31, 2017, increased $10.7 million, or 31.3%, to $45.0 million from $34.3 million for the year ended December 31, 2016.  This increase primarily is due to the aforementioned provision for the common stock warrants issued to Amazon.com NV Investment Holdings LLC, costs associated with increased headcount and increased insurance costs.

On April 4, 2017, the Company issued to Amazon.com NV Investment Holdings LLC a warrant to acquire up to 55,286,696 shares of common stock, subject to certain vesting events. The first tranche of 5,819,652 warrant shares vested upon the issuance of the warrant and was not contingent on future sales, and as a result, $7.1 million, the fair value of the first tranche warrant shares, including legal and other fees associated with the negotiation and completion of the agreement, was recognized as selling, general and administrative expense on the accompanying consolidated statement of operations for the year ended December 31, 2017.

Selling, general and administrative expenses for the year ended December 31, 2016, was $34.3 million, consistent with $34.2 million for the year ended December 31, 2015. There was a $1.4 million increase in stock-based compensation expense, impacted by the increases in the fair value of stock options granted in recent years and rising headcount, offset by approximately a $2.4 million decrease in performance-based bonuses.

Interest and other expense (income), net. Interest and other expense, net consists of interest and other expenses related to interest on our short-term borrowing, long-term debt, obligations under capital lease and our finance obligations, as well as foreign currency exchange gain (loss), offset by interest and other income consisting primarily of interest earned on our cash and cash equivalents, note receivable, and other income.  During 2016 and 2017, the Company entered into a series of capital leases with Generate Lending LLC and Wells Fargo. In December 2016, the Company entered into a loan and security agreement with NY Green Bank, which was amended in 2017.

Net interest and other expense for the year ended December 31, 2017, decreased $0.6 million as compared to the year ended December 31, 2016.  The decrease is attributed to a reduction of one-time fees incurred in 2016, offset by increases in the outstanding finance obligation balance.

Net interest and other expense, net for the year ended December 31, 2016, increased $10.4 million as compared to the year ended December 31, 2015.  The increase is primarily attributed to $5.0 million in accelerated interest, early termination fees, and accelerated amortization of debt issuance costs related to the Hercules Capital, Inc. loan and security agreement, $3.6 million of interest on the Hercules Capital, Inc. loan and security agreement, and $2.1 million of interest expense related to the Generate Lending LLC loan agreement, offset by interest and other income which remained relatively insignificant for the year ended December 31, 2016, as compared to December 31, 2015.

Change in fair value of common stock warrant liability. The Company accounts for liability classified common stock warrants within the common stock warrant liability with changes in the fair value reflected in the consolidated statement of operations as change in the fair value of common stock warrant liability.

The change in fair value of common stock warrant liability for the year ended December 31, 2017 resulted in an increase (loss) in the associated warrant liability of $15.2 million, as compared to a decrease (gain) in the associated warrant liability of $4.3 million for year ended December 31, 2016, and a decrease (gain) of $3.7 million for the year ended December 31, 2015. These variances from year to year are primarily due to changes in the number of warrants outstanding, the average term, the Company’s common stock share price, and changes in volatility of our common stock, which are significant inputs to the Black-Scholes valuation model.

Income taxes.  The deferred tax asset generated from our net operating loss has been offset by a full valuation allowance because it is more likely than not that the tax benefits of the net operating loss carry forward will not be realized. The Company also recognizes accrued interest and penalties related to unrecognized tax benefits as a component of income tax expense.

During the year ended December 31, 2016, the Company released its liability for unrecognized tax benefits of $392 thousand, as the related statute of limitations expired.  No other tax expense or benefit was recognized in the years ended December 31, 2017, 2016 or 2015.

Liquidity and Capital Resources

Our cash requirements relate primarily to working capital needed to operate and grow our business, including funding operating expenses, growth in inventory to support both shipments of new units and servicing the installed base, growth in equipment leased to customers under long-term arrangements, funding the growth in our GenKey “turn-key” solution, which includes the installation of our customers’ hydrogen infrastructure as well as delivery of the hydrogen fuel,  continued development and expansion of our products, payment of lease obligations under sale/leaseback financings, and

the repayment or refinancing of our long-term debt. Our ability to achieve profitability and meet future liquidity needs and capital requirements will depend upon numerous factors, including the timing and quantity of product orders and shipments; attaining and expanding positive gross margins across all product lines; the timing and amount of our operating expenses; the timing and costs of working capital needs; the ability of our customers to obtain financing to support commercial transactions; our ability to obtain financing arrangements to support the sale or leasing of our products and services to customers and to repay or refinance our long-term debt, and the terms of such agreements that may require us to pledge or restrict substantial amounts of our cash to support these financing arrangements; the timing and costs of developing marketing and distribution channels; the timing and costs of product service requirements; the timing and costs of hiring and training production staff; the extent to which our products gain market acceptance; the timing and costs of product development and introductions; the extent of our ongoing and new research and development programs; and changes in our strategy or our planned activities. If we are unable to fund our operations with positive cash flows and cannot obtain external financing, we may not be able to sustain future operations.  As a result, we may be required to delay, reduce and/or cease our operations and/or seek bankruptcy protection.

We have experienced and continue to experience negative cash flows from operations and net losses.  The Company incurred net losses attributable to common shareholders of $130.2 million, $57.6 million and $55.8 million for the years ended December 31, 2017, 2016, and 2015, respectively, and has an accumulated deficit of $1.2 billion at December 31, 2017.

During the year ended December 31, 2017, cash used in operating activities was $60.2 million, consisting primarily of a net loss attributable to the Company of $127.1 million, offset by the impact of noncash charges of $71.3 million and net outflows from fluctuations in working capital and other assets and liabilities of $4.4 million. The changes in working capital primarily were related to building of inventory and an increase in accounts receivable and prepaid expenses offset by an increase of accounts payable and deferred revenue. As of December 31, 2017, we had cash and cash equivalents of $24.8 million and net working capital of $3.9 million. By comparison, at December 31, 2016, we had cash and cash equivalents of $46.0 million and net working capital of $44.4 million. 

Net cash used in investing activities for the year ended December 31, 2017, totaled $44.4 million and included purchases of property, plant and equipment and outflows associated with materials, labor, and overhead necessary to construct new leased property. Cash outflows related to equipment that we sell and equipment we lease directly to customers are included in net cash used in operating activities and net cash used in investing activities, respectively. Net cash provided by financing activities for the year ended December 31, 2017 totaled $83.0 million and primarily resulted from net proceeds of $23.0 million pursuant to public offerings of common stock, net proceeds from borrowing of long-term debt of $20.1 million, net proceeds of $17.6 million pursuant to exercise of warrants, an increase in finance obligations of $26.7 million and a decrease in restricted cash of $11.4 million, offset by redemption of Series D preferred stock of  $3.7 million and principal payments of long-term debt of $12.3 million. 

In previous years, the Company entered into sale/leaseback agreements with various financial officerinstitutions to facilitate the Company’s commercial transactions with key customers. The Company sold certain fuel cell systems and hydrogen infrastructure to the financial institutions, and leased the equipment back to support certain customer locations and to fulfill its varied PPAs.  In connection with these operating leases, the financial institutions require the Company to maintain cash balances in restricted accounts securing the Company’s lease obligations. Cash received from customers under the PPAs is used to make lease payments.  As the Company performs under these agreements, the required restricted cash balances are released, according to a set schedule. The total remaining lease payments to financial institutions under these agreements was $33.4 million, which has been fully secured with restricted cash and pledged service escrows.

In connection with the consummation of the Walmart Transaction Agreement described below, the Company entered into a master lease agreement with Wells Fargo (Wells Fargo MLA) to finance the Company’s commercial transactions with Wal-mart Stores Inc. (Walmart). Pursuant to the Wells Fargo MLA, the Company sells fuel cell systems and hydrogen infrastructure to Wells Fargo and then leases them back and operates them at Walmart sites under lease arrangements with Walmart.  The total remaining lease payments to Wells Fargo was $26.3 million at December 31, 2017. During 2017, the Company also entered into an amended and restated master lease agreement with Generate Capital (Generate Capital MLA) to finance the Company’s commercial transactions with Walmart. The total remaining lease payments to Generate Capital was $45.5 million at December 31, 2017. The Wells Fargo MLA and the Generate Capital MLA do not require the Company to maintain any restricted cash.

We have historically funded our operations primarily through public and private offerings of common and preferred stock, as well as short-term borrowings and long-term debt and project financing, as described below.  The Company believes that its current working capital and cash anticipated to be generated from future operations, as well as borrowings from lending and project financing sources and proceeds from equity offerings, will provide sufficient liquidity to fund operations for at least one year after the date that the financial statements are issued. There is no guarantee that future funding will be available if and when required or at terms acceptable to the Company.  This projection is based on our current expectations regarding new project financing and product sales and service, cost structure, cash burn rate and other operating assumptions. Additionally, the Company has other capital sources available, including the At Market Issuance Sales Agreement.

Several key indicators of liquidity are summarized in the following table (in thousands):

Amazon.com, Inc., Transaction Agreement

On April 4, 2017, the Company and Amazon.com, Inc. (Amazon) entered a Transaction Agreement (Amazon Transaction Agreement), pursuant to which the Company issued to Amazon.com NV Investment Holdings LLC, a wholly owned subsidiary of Amazon, a warrant  (Amazon Warrant) to acquire up to 55,286,696 shares of the Company’s common stock (Amazon Warrant Shares), subject to certain vesting events described below. The Company and Amazon entered into the Amazon Transaction Agreement in connection with existing commercial agreements between the Company and Amazon with respect to the deployment of the Company’s GenKey fuel cell technology at Amazon distribution centers. The existing commercial agreements contemplate, but do not guarantee, future purchase orders for the Company’s fuel cell technology. The vesting of the Amazon Warrant Shares is linked to payments made by Amazon or its affiliates (directly or indirectly through third parties) pursuant to the existing commercial agreements.

The majority of the Amazon Warrant Shares will vest based on Amazon’s payment of up to $600.0 million to the Company in connection with Amazon’s purchase of goods and services from the Company. The first tranche of 5,819,652 Amazon Warrant Shares vested upon the execution of the Amazon Transaction Agreement.  Accordingly, $6.7 million (the fair value of the first tranche of Amazon Warrant Shares) was recognized as selling, general and administrative expense on the accompanying consolidated statement of operations for the year ended December 31, 2017. The second tranche of 29,098,260 Amazon Warrant Shares will vest in four installments of 7,274,565 Amazon Warrant Shares each time Amazon or its affiliates, directly or indirectly through third parties, make an aggregate of $50.0 million in payments for goods and services to the Company, up to payments totaling $200.0 million in the aggregate. During the year ended December 31, 2017, the first installment of the second tranche vested. The exercise price for the first and second tranches of Amazon Warrant Shares is $1.1893 per share. After Amazon has made payments to the Company totaling $200.0 million, the third tranche of 20,368,784 Amazon Warrant Shares will vest in eight installments of 2,546,098 Amazon Warrant Shares each time Amazon or its affiliates, directly or indirectly through third parties, make an aggregate of $50.0 million in payments for goods and services to the Company, up to payments totaling $400.0 million in the aggregate. The exercise price of the third tranche of Amazon Warrant Shares will be an amount per share equal to ninety percent (90%) of the 30-day volume weighted average share price of the common stock as of the final vesting date of the second tranche of Amazon Warrant Shares. The Amazon Warrant is exercisable through April 4, 2027.

The Amazon Warrant provides for net share settlement that, if elected by the holders, will reduce the number of shares issued upon exercise to reflect net settlement of the exercise price. The Amazon Warrant provides for certain adjustments that may be made to the exercise price and the number of Amazon Warrant Shares issuable upon exercise due to customary anti-dilution provisions based on future events.  The Amazon Warrant is classified as an equity instrument.

Because the Amazon Warrant contains performance criteria (i.e. aggregate purchase levels), which Amazon must achieve for the Amazon Warrant Shares to vest, as detailed above, the final measurement date for the Amazon Warrant

Shares is the date on which the Amazon Warrant Shares have vested. Prior to the final measurement, when achievement of the performance criteria has been deemed probable, the estimated fair value of the Amazon Warrant Shares is being recorded as a reduction to revenue and an addition to additional paid-in capital based on the projected number of Amazon Warrant Shares expected to vest, the proportion of purchases by Amazon and its affiliates within the period relative to the aggregate purchase levels required for the Amazon Warrant Shares to vest and the then-current fair value of the related Amazon Warrant Shares. To the extent that projections change in the future as to the number of Amazon Warrant Shares that will vest, as well as changes in the fair value of the Amazon Warrant Shares, a cumulative catch-up adjustment will be recorded in the period in which the estimates change.

At December 31, 2017, 13,094,217 of the Amazon Warrant Shares had vested.  The amount of selling, general and administrative expense attributed to this first tranche recorded in April 2017, was $7.1 million, including legal and other fees associated with the negotiation and completion of the agreement.  The amount of provision for common stock warrants recorded as a reduction of revenue for the Amazon Warrant during the year ended December 31, 2017 was $17.3 million. 

Wal-Mart Stores Inc., Transaction Agreement

On July 20, 2017, the Company and Walmart entered into a Transaction Agreement (Walmart Transaction Agreement), pursuant to which the Company issued to Walmart a warrant (Walmart Warrant) to acquire up to 55,286,696 shares of the Company’s common stock (Walmart Warrant Shares), subject to certain vesting events. The Company and Walmart entered into the Walmart Transaction Agreement in connection with existing commercial agreements between the Company and Walmart with respect to the deployment of the Company’s GenKey fuel cell technology across various Walmart distribution centers. The existing commercial agreements contemplate, but do not guarantee, future purchase orders for the Company’s fuel cell technology. The vesting of the warrant shares, is linked to payments made by Walmart or its affiliates (directly or indirectly through third parties) pursuant to transactions entered into after January 1, 2017 under existing commercial agreements.

The majority of the Walmart Warrant Shares will vest based on Walmart’s payment of up to $600.0 million to the Company in connection with Walmart’s purchase of goods and services from the Company. The first tranche of 5,819,652 Walmart Warrant Shares vested upon the execution of the Walmart Transaction Agreement.  Accordingly, $10.9 million (the fair value of the first tranche of Walmart Warrant Shares) was recorded as a provision for common stock warrants and presented as a reduction to revenue on the accompanying consolidated statement of operations for the year ended December 31, 2017. The second tranche of 29,098,260 Walmart Warrant Shares will vest in four installments of 7,274,565 Walmart Warrant Shares each time Walmart or its affiliates, directly or indirectly through third parties, make an aggregate of $50.0 million in payments for goods and services to the Company, up to payments totaling $200.0 million in the aggregate. The exercise price for the first and second tranches of Walmart Warrant Shares is $2.1231 per share. After Walmart has made payments to the Company totaling $200.0 million, the third tranche of 20,368,784 Walmart Warrant Shares will vest in eight installments of 2,546,098 Walmart Warrant Shares each time Walmart or its affiliates, directly or indirectly through third parties, make an aggregate of $50.0 million in payments for goods and services to the Company, up to payments totaling $400.0 million in the aggregate. The exercise price of the third tranche of Walmart Warrant Shares will be an amount per share equal to ninety percent (90%) of the 30-day volume weighted average share price of the common stock as of the final vesting date of the second tranche of Walmart Warrant Shares, provided that, with limited exceptions, the exercise price for the third tranche will be no lower than $1.1893. The Walmart Warrant is exercisable through July 20, 2027.

The Walmart Warrant provides for net share settlement that, if elected by the holder, will reduce the number of shares issued upon exercise to reflect net settlement of the exercise price. The Walmart Warrant provides for certain adjustments that may be made to the exercise price and the number of shares of common stock issuable upon exercise due to customary anti-dilution provisions based on future events.  The Walmart Warrant is classified as an equity instrument.

Because the Walmart Warrant contains performance criteria (i.e. aggregate purchase levels), which Walmart must achieve for the Walmart Warrant Shares to vest, as detailed above, the final measurement date for the Walmart Warrant is the date on which the Walmart Warrant Shares have vested. Prior to the final measurement, when achievement of the performance criteria has been deemed probable, the estimated fair value of the Walmart Warrant is being recorded as a reduction to revenue and an addition to additional paid-in capital based on the projected number of Walmart Warrant Shares expected to vest, the proportion of purchases by Walmart and its affiliates within the period relative to the aggregate purchase levels required for the Walmart Warrant Shares to vest and the then-current fair value of the related Walmart

Warrant Shares. To the extent that projections change in the future as to the number of Walmart Warrant Shares that will vest, as well as changes in the fair value of the Walmart Warrant Shares, a cumulative catch-up adjustment will be recorded in the period in which the estimates change.

At December 31, 2017, 5,819,652 of the Walmart Warrant Shares had vested.  The amount of provision for common stock warrants recorded as a reduction to revenue for the Walmart Warrant during the year ended December 31, 2017 was $12.4 million.

NY Green Bank Loan

On December 23, 2016, the Company, and its subsidiaries Emerging Power Inc. and Emergent Power Inc. entered into a loan and security agreement with NY Green Bank, a Division of the New York State Energy Research & Development Authority (NY Green Bank), pursuant to which NY Green Bank made available to the Company a secured term loan facility in the amount of $25.0 million, subject to certain terms and conditions.  The Company borrowed $25.0 million upon closing and incurred costs of $1.2 million.  On July 21, 2017, the Company and NY Green Bank entered into an amendment to the loan and security agreement (as amended, Term Loan Facility), which among other things, provided for an additional $20.0 million term loan, increasing the size of the total commitment to $45.0 million, amended the interest rate, prepayment penalty (for any prepayment in the calendar year 2017 or 2018, a prepayment charge equal to 7.5% of the advance amount being prepaid will apply) and product deployment and employment targets.  As with the prior facility, the new facility will be repaid primarily as the Company’s various restricted cash reserves are released over the term of the facility. During the year ended December 31, 2017, the Company borrowed the additional $20.0 million under the facility and incurred closing costs of $0.5 million. At December 31, 2017, the outstanding principal balance under the Term Loan Facility was $32.8 million.  The fair value of the Term Loan Facility approximates the carrying value as of December 31, 2017, due to the variable interest rate of the Term Loan Facility. 

Advances under the Term Loan Facility bear interest at a rate equal to the sum of (i) the LIBOR rate for the applicable interest period, plus applicable margin of 9.5%. The interest rate at December 31, 2017 was approximately 10.8%.  The Term Loan Facility has a maturity date of December 23, 2019.  As of December 31, 2017, estimated remaining principal payments will be approximately $19.1 million and $13.7 million during the years ending December 31, 2018, and 2019, respectively.  These payments will be funded by restricted cash released, as described in Note 19, Commitments and Contingencies.

Interest and a varying portion of the principal amount is payable on a quarterly basis and the entire then outstanding principal balance of the Term Loan Facility, together with all accrued and unpaid interest, is due and payable on the maturity date.  On the maturity date, the Company may also be required to pay additional fees of up to $1.8 million if the Company is unable to meet certain goals related to the deployment of fuel cell systems in the State of New York and increasing the Company’s number of full-time employees in the State of New York. 

The Term Loan Facility is secured by substantially all of the Company’s and the guarantor subsidiaries’ assets, including, among other assets, all intellectual property, all securities in domestic subsidiaries and 65% of the securities in foreign subsidiaries, subject to certain exceptions and exclusions.

The Term Loan Facility contains covenants, including, among others, (i) the provision of annual and quarterly financial statements, management rights and insurance policies and (ii) restrictions on incurring debt, granting liens, making acquisitions, making loans, paying dividends, dissolving, and entering into leases and asset sales.  The Term Loan Facility also provides for events of default, including, among others, payment, bankruptcy, covenant, representation and warranty, change of control, judgment and material adverse effect defaults at the discretion of the lender.

The Term Loan Facility provides that if there is an event of default due to the Company’s insolvency or if the Company fails to perform, in any material respect, the servicing requirements for fuel cell systems under certain customer agreements, which failure would entitle the customer to terminate such customer agreement, replace the Company or withhold the payment of any material amount to the Company under such customer agreement, then the NY Green Bank has the right to cause a wholly owned subsidiary of the Company to replace the Company in performing the maintenance services under such customer agreement.

Redeemable Convertible Preferred Stock

In December 2016, the Company completed an offering of an aggregate of 18,500 shares of the Company’s Series D Redeemable Preferred Stock, par value $0.01 per share (the “Series D Preferred Stock”) and warrants to purchase 7,381,500 shares of the Company’s common stock, par value $0.01 per share (the “Common Stock”), resulting in aggregate proceeds of approximately $15.6 million. During the year ended December 31, 2017, the Company redeemed 3,700 shares of the Series D Preferred Stock, at an aggregate redemption price of approximately $3.7 million.  On April 5, 2017, all of the remaining outstanding shares of the Series D Preferred Stock were converted into an aggregate of 9,548,393 shares of the Company’s common stock at a conversion price of $1.55.  The conversion was done at the election of the holder in accordance with the terms of the Series D Preferred Stock. After the conversion, no shares of Series D Preferred Stock remain outstanding. In December 2017, the Series D Preferred Stock was deauthorized by the Board of Directors.

During 2017, 2,611 shares of the Company’s Series C Redeemable Preferred Stock, par value $0.01 per share (the “Series C Preferred Stock”) were converted to common stock.  At December 31, 2017, there were outstanding 2,620 shares of Series C Preferred Stock. 

Income Taxes

Under Internal Revenue Code (IRC) Section 382, the use of loss carryforwards may be limited if a change in ownership of a company occurs. If it is determined that due to transactions involving the Company’s shares owned by its 5 percent or greater shareholders a change of ownership has occurred under the provisions of IRC Section 382, the Company's federal and state net operating loss carryforwards could be subject to significant IRC Section 382 limitations.

Based on studies of the changes in ownership of the Company, it has been determined that an IRC Section 382 ownership change occurred in 2013 that limited the amount of pre-change net operating losses that can be used in future years to $13.5 million.  Net operating losses of $152.4 million incurred after the most recent ownership change are not subject to IRC Section 382 and are available for use in future years.  Accordingly, the Company's deferred tax assets include $165.9 million of U.S. net operating loss carryforwards.  The net operating loss carryforwards available at December 31, 2017, if unused will expire at various dates from 2032 through 2037.

Approximately $1.4 million of research credit carryforwards generated after the most recent IRC Section 382 ownership change are included in the Company's deferred tax assets. Due to limitations under IRC Section 382, research credit carryforwards existing prior to the most recent IRC Section 382 ownership change will not be used and are not reflected in the Company's gross deferred tax asset at December 31, 2017.  The remaining credit carryforwards will expire during the periods 2033 through 2037.

The Tax Cuts and Jobs Act (the "Act") was enacted on December 22, 2017. The Act makes broad and complex changes to the U.S. tax code including a reduction of the U.S. federal corporate tax rate from 35 percent to 21 percent effective for the 2018 tax year.  Accordingly, federal deferred tax assets were adjusted by $42.5 million to reflect the reduction in tax rates and the valuation allowance was also reduced by $42.5 million resulting in no change to the net deferred tax asset.  The deferred tax asset adjustments reduced the tax benefit of the current year losses by 33.5% as shown in the effective tax rate schedule.  The valuation allowance rate impact includes an offsetting 33.5% for the tax rate reduction resulting in no change to the provision for income taxes. 

The Act also requires companies to pay a one-time transition tax on certain unrepatriated foreign earnings and profits from foreign subsidiaries.  No transition tax applies as the Company’s foreign subsidiaries have no earnings and profits.

Contractual Obligations

Contractual obligations as of December 31, 2017, under agreements with non‑cancelable terms are as follows (in thousands):

Critical Accounting Estimates

The preparation of financial statements in conformity with U.S. generally accepted accounting principles and related disclosures requires management to make estimates and assumptions.

We believe that the following are our most critical accounting estimates and assumptions the Company must make in the preparation of its Consolidated Financial Statements and related disclosures:

Revenue Recognition:  The Company recognizes revenue under arrangements for products and services, which may include the sale of products and related services, including revenue from installation, service and maintenance, spare parts, hydrogen fueling services (which may include hydrogen supply as well as hydrogen fueling infrastructure) and leased units. The Company also recognizes revenue under research and development contracts, which are primarily cost reimbursement contracts associated with the development of PEM fuel cell technology.

The Company enters into revenue arrangements that may contain a combination of fuel cell systems and infrastructure, installation, service, maintenance, spare parts, and other support services. Revenue arrangements containing fuel cell systems and related infrastructure may be sold, or provided to customers under a PPA.

When sold to customers, the Company accounts for each separate deliverable of these multiple deliverable arrangements as a separate unit of accounting if the delivered item or items have value to the customer on a standalone basis. The Company considers a deliverable to have standalone value if the item is sold separately by us or another entity or if the item could be resold by the customer. The Company allocates revenue to each separate deliverable based on its relative selling price. For a majority of our deliverables, the Company determines relative selling prices using its best

estimate of the selling price since vendor-specific objective evidence and third-party evidence is generally not available for the deliverables involved in its revenue arrangements due to a lack of a competitive environment in selling fuel cell technology. When determining estimated selling prices, the Company considers the Company’s ongoing pricing strategy and policies, the cost to produce the deliverable, a reasonable gross margin on that deliverable, the selling price and profit margin for similar products and services, the value of any enhancements that have been built into the deliverable and the characteristics of the varying markets in which the deliverable is sold, as applicable. The Company determines estimated selling prices for deliverables in its arrangements based on the specific facts and circumstances of each arrangement and analyzes the estimated selling prices used for its allocation of consideration of each arrangement.

Once relative selling prices are determined, the Company proportionately allocates the sale consideration to each element of the arrangement. The allocated sales consideration related to fuel cell systems and infrastructure, spare parts, and hydrogen infrastructure is recognized as revenue at shipment if title and risk of loss have passed to the customer, there is persuasive evidence of an arrangement, the sales price is fixed or determinable, collection of the related receivable is reasonably assured, and customer acceptance criteria, if any, have been successfully demonstrated. The allocated sales consideration related to service and maintenance is generally recognized as revenue on a straight-line basis over the term of the contract, as appropriate.

For those customers who do not purchase an extended maintenance contract, the Company does not include a right of return on its products other than rights related to standard warranty provisions that permit repair or replacement of defective goods. The Company accrues for anticipated standard warranty costs at the same time that revenue is recognized for the related product.  Only a limited number of fuel cell units are under standard warranty.

In a vast majority of its commercial transactions, the Company sells extended maintenance contracts that generally provide for a five to ten year warranty from the date of product installation. These types of contracts are accounted for as a separate deliverable, and accordingly, revenue generated from these transactions is deferred and recognized in income over the warranty period, generally on a straight-line basis. Additionally, the Company may enter into annual service and extended maintenance contracts that are billed monthly. Revenue generated from these transactions is recognized in income on a straight-line basis over the term of the contract. Costs are recognized as incurred over the term of the contract.  When costs are projected to exceed revenues on the life of the contract, an accrual for loss contracts is recorded.  Costs are estimated based upon historical experience, contractual agreements and the estimated impact of the Company’s cost reduction initiatives.  The actual results may differ from these estimates.

When fuel cell systems and related infrastructure are provided to customers through a Power Purchase Agreement, or PPA, revenues associated with these agreements are treated as rental income and recognized on a straight-line basis over the life of the agreements.  In conjunction with entering into a PPA with a customer, the Company may enter into sale/leaseback transactions with third-party financial institutions, whereby the fuel cells, related infrastructure, and service are sold to the third-party financial institution and leased back to the Company through either an operating or capital lease.

The Company purchases hydrogen fuel from suppliers and sells to its customers upon delivery.  Revenue and cost of revenue related to this fuel is recorded as dispensed, and included in the respective “Fuel delivered to customers” lines on the accompanying consolidated statements of operations.

One of the critical estimates that management makes is the projection of service costs related to GenDrive units under extended maintenance contracts. This estimate is important in management’s determination of whether a loss contract exists, as well as the amount of any loss. When projected costs to be incurred over the remaining life of the extended maintenance contracts is estimated to exceed contractual revenues, a provision for loss contracts related to service is recorded. An analysis of projected expenses and revenues is performed on each extended maintenance contract. Cost of expected maintenance contracts consist of replacement parts, labor and overhead. A variety of assumptions are included in the estimates of future service costs, including the life of parts, failure rates of parts, and future costs of parts.

Contract accounting is used for research and development contract revenue. The Company generally shares in the cost of these programs with cost sharing percentages ranging from 30% to 50% of total project costs. Revenue from time and material contracts is recognized on the basis of hours expended plus other reimbursable contract costs incurred during the period and is included within the “other” revenue line on the consolidated statement of operations. All allowable work performed through the end of each calendar quarter is billed, subject to limitations in the respective contracts. We

expect to continue research and development contract work that is directly related to our current product development efforts. 

Valuation of long‑lived assets:  We assess the potential impairment of long‑lived assets, including identifiable intangible assets, whenever events or changes in circumstances indicate that the carrying value may not be recoverable. Factors we consider important that could trigger an impairment review include, but are not limited to, the following:

When we determine that the carrying value of long‑lived assets, including identifiable intangible assets, may not be recoverable based upon the existence of one or more of the above indicators of impairment, we would measure any impairment based upon the provisions of Financial Accounting Standards Board (FASB) ASC No. 350‑35‑30‑14, Intangibles—Goodwill and Other, and FASB ASC No. 360‑10‑35‑15, Impairment or Disposal of Long‑Lived Assets, as appropriate. Any resulting impairment loss could have a material adverse impact on our financial condition and results of operations.

Warrant Accounting:    The Company accounts for common stock warrants as either derivative liabilities or as equity instruments depending on the specific terms of the respective warrant agreements, as follows:

Derivative Liabilities

Registered common stock warrants that require the issuance of registered shares upon exercise and do not sufficiently preclude an implied right to cash settlement are accounted for as derivative liabilities. We currently classify these derivative warrant liabilities on the accompanying consolidated balance sheets as a long-term liability, which is revalued at each balance sheet date subsequent to the initial issuance, using the Black-Scholes pricing model. This pricing model, which is based, in part, upon unobservable inputs for which there is little or no market data, requires the Company to develop its own assumptions. Changes in the fair value of the warrants are reflected in the accompanying consolidated statements of operations as change in fair value of common stock warrant liability.

There was no expected dividend yield for the warrants granted. If factors change and different assumptions are used, the warrant liability and the change in estimated fair value could be materially different. Generally, as the market price of our common stock increases, the fair value of the warrant increases, and conversely, as the market price of our common stock decreases, the fair value of the warrant decreases. Also, a significant increase in the volatility of the market price of the Company’s common stock, in isolation, would result in a significantly higher fair value measurement; and a significant decrease in volatility would result in a significantly lower fair value measurement. Changes in the fair value of the warrants are reflected in the consolidated statements of operations as change in fair value of common stock warrant liability.

Equity Instruments

Common stock warrants that meet certain applicable requirements of ASC Subtopic 815-40, Derivatives and Hedging – Contracts in Entity’s Own Equity, and other related guidance, including the ability of the Company to settle the warrants without the issuance of registered shares or the absence of rights of the holder to require cash settlement, are accounted for as equity instruments. The Company classifies these equity instruments within additional paid-in capital on the accompanying consolidated balance sheets. Common stock warrants accounted for as equity instruments represent the warrants issued to Amazon.com, Inc. and Wal-Mart Stores, Inc.  These warrants are remeasured at each financial reporting date prior to vesting, using the Monte Carlo pricing model.  Once these warrants vest, they are no longer remeasured.  This pricing model, which is based, in part, upon unobservable inputs for which there is little or no market data, requires the Company to develop its own assumptions. Changes in fair value resulting from remeasurement of common stock warrants

issued in connection with the Amazon Transaction Agreement and the Walmart Transaction Agreement are recorded as cumulative catch up adjustments as a reduction of revenue.

There was no expected dividend yield for the warrants granted.

Recent Accounting Pronouncements

In July 2017, an accounting update was issued to address narrow issues identified as a result of the complexity associated with applying generally accepted accounting principles (GAAP) for certain financial instruments with characteristics of liabilities and equity. This update addresses the complexity of accounting for certain financial

instruments with down round features. Down round features are features of certain equity-linked instruments (or embedded features) that result in the strike price being reduced on the basis of the pricing of future equity offerings. The Company early adopted this accounting update during the three months ended June 30, 2017. The adoption of this accounting update was considered in determining that warrants issued during the second quarter of 2017 were equity classified.

In January 2017, an accounting update was issued to simplify how an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test.  Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. This accounting update is effective for years beginning after December 15, 2019.  Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company is evaluating the impact this update will have on the consolidated financial statements.

In November 2016, an accounting update was issued to reduce the existing diversity in the classification and presentation of changes in restricted cash on the statement of cash flows. This accounting update is effective for years beginning after December 15, 2017, and interim periods within those fiscal years and is required to be adopted retrospectively. The Company expects adoption of this update to impact cash flows from financing activities due to the change in the presentation of its restricted cash balance on the consolidated financial statements.    Net cash provided by (used in) financing activities and decrease in cash and cash equivalents for the years ended December 31, 2017, 2016, and 2015, are expected to (decrease) increase by ($11.4 million), $6.8 million, and $47.3 million, respectively.

In October 2016, an accounting update was issued to simplify how an entity should recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs.  Consequently, the amendments in this update eliminate the exception for an intra-entity transfer of an asset other than inventory.  Two common examples of assets included in the scope of this update are intellectual property and property, plant, and equipment.  This accounting update is effective for the annual periods beginning after December 15, 2017 and interim periods within those years. The Company does not expect the adoption of this update to have a significant effect on the consolidated financial statements.

In August 2016, an accounting update was issued to reduce the existing diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows.  This accounting update is effective for fiscal years beginning after December 15, 2018, and interim periods within fiscal years beginning after December 15, 2019. Early adoption is permitted, including adoption in an interim period.  The Company is evaluating the impact this update will have on the consolidated financial statements.

In March 2016, an accounting update was issued to simplify several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows.  This accounting update is effective for annual periods beginning after December 15, 2016, and interim periods within those periods.  The Company adopted this update and it did not have a significant effect on the consolidated financial statements.

In February 2016, an accounting update was issued which requires balance sheet recognition for operating leases, among other changes to previous lease guidance.  This accounting update is effective for fiscal years beginning after December 15, 2018.  While the Company is evaluating the impact this update will have on the consolidated financial statements, it is expected that the future minimum lease payments under non-cancelable leases, as lessee, will be recorded on the Company’s consolidated balance sheets, offset by a right-of-use asset.

In June 2014, an accounting update was issued that replaces the existing revenue recognition framework regarding contracts with customers. The Company adopted this accounting update as of January 1, 2018. The standard outlines a five-step model whereby revenue is recognized as performance obligations within a contract are satisfied. The standard also requires new, expanded disclosures regarding revenue recognition. The Company will use the modified retrospective basis method to account for the transition. The Company did not experience a significant effect on the timing and amount of revenue recognized or the amount of revenue allocated to the identified performance obligations. There is an insignificant amount of historical contract acquisition costs that were expensed under current guidance and will not be capitalized upon adoption of ASC Subtopic 606. However, in subsequent periods, contract acquisition costs will be capitalized in accordance with ASC  Subtopic 606.

Item 7A.  Quantitative and Qualitative Disclosures about Market Risk

From time to time, we may invest our cash in government, government backed and interest‑bearing investment‑grade securities that we generally hold for the duration of the term of the respective instrument. We do not utilize derivative financial instruments, derivative commodity instruments or other market risk sensitive instruments, positions or transactions in any material fashion. We are not subject to any material risks arising from changes in interest rates, foreign currency exchange rates, commodity prices, equity prices or other market changes that affect market risk sensitive instruments.

Our exposure to changes in foreign currency rates is primarily related to sourcing inventory from foreign locations and operations of HyPulsion. This practice can give rise to foreign exchange risk resulting from the varying cost of inventory to the receiving location. The Company reviews the level of foreign content as part of its ongoing evaluation of overall sourcing strategies and considers the exposure to be not significant. Our HyPulsion exposure is mitigated by the present low level of operation. Its sourcing is primarily intercompany in nature and denominated in U.S. dollar.

Item 8.  Financial Statements and Supplementary Data

The Company’s Consolidated Financial Statements included in this report beginning at page F‑1 are incorporated in this Item 8 by reference.

Item 9.  Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

None.

Item 9A.  Controls and Procedures

As required by Rule 12b-1513a 15(b) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). The certifications, we have carried out an evaluation, under the supervision and with the participation of our principal executive officermanagement, including our Chief Executive Officer and principal financial officer are filed with this Amendment as Exhibits 31.1 and 31.2 hereto.

Except as expressly noted herein, this Form 10-K/A does not amend, update or change any other items or disclosures in the Original Form 10-K and does not purport to reflect any information or events subsequent to the filingour Chief Financial Officer, of the Original Form 10-K.  Accordingly, this Form 10-K/A should be read in conjunction with the Original Form 10-K and our other reports filed with the SEC subsequent to the filingeffectiveness, as of the Original Form 10-K.

INDEX TO FORM 10-K/A

PART III

PART III

ITEM 10.     DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE

(a)     DIRECTORS

The number of directorsend of the Company is presently fixed at ten (10),period covered by this report, of the design and the Boardoperation of Directors currently consists of ten(10) members. The Board of Directors is divided into three classes, with three (3) directors in Class I, four (4) directors in Class II,our "disclosure controls and three (3) directors in Class III. Directors in Classes I, II and III serve for three-year terms with one class of directors being elected by the Company’s stockholders at each Annual Meeting of Stockholders.

The Board of Directors has determined that Ms. Helmer and Messrs. Garberding, Schneider, McNamee, Willis, Hickey, Roth and Kenausis are independent directorsprocedures" as defined in Rule 5605(a)(2)13a-15(e) promulgated by the SEC under the Marketplace Rules of the National Association of Securities Dealers, Inc. (the “NASDAQ Rules”).

The positions ofExchange Act. Based upon that evaluation, our Chief Executive Officer and Chairmanour Chief Financial Officer concluded that our disclosure controls and procedures, as of the Boardend of Directorssuch period, were adequate and effective to ensure that information required to be disclosed by us in the reports that we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms, and that such information was accumulated and communicated to management, as appropriate, to allow timely decisions regarding required disclosure.

The Company’s management is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Rule 13a‑15(f) and 15d‑15(f) under the Exchange Act. The Company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of

financial reporting and the preparation of financial statements for external purposes in accordance with U.S. generally accepted accounting principles, and includes those policies and procedures that:

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are currently each filled by a different individual, Andrew Marsh and George C. McNamee, respectively. Ifsubject to the positionrisk that controls may become inadequate because of Chairmanchanges in conditions, or that the degree of compliance with the Board of Directors is vacant,policies or if he or she is absent, theprocedures may deteriorate.

The Company’s management, including our Chief Executive Officer presides, when present, at meetings of stockholders and of the Board of Directors.

Set forth below is certain information regarding the directors of the Company The ages of and biographical information regarding each director is based on information furnished to the Company by each director and isour Chief Financial Officer, assessed as of April 28, 2017.

George C. McNamee serves as Chairmaneffectiveness of the Company’s Boardinternal control over financial reporting. In making this assessment, management used the criteria set forth in the framework in Internal Control—Integrated Framework (2013) issued by the Committee of Directors and has served as such since 1997. He was previously Chairman of First Albany Companies (now GLCH) and a Managing Partner of FA Tech Ventures, an information and energy technology venture capital firm. Mr. McNamee’s background in investment banking has given him broad exposure to many financing and merger and acquisition issues. As an executive, he has dealt with rapid- growth companies, technological change, crisis management, team building and strategy. As a public company director, Mr. McNamee has led board special committees, chaired audit committees, chaired three boards and has been an active lead director. Mr. McNamee has previously served on public company boards, including Mechanical Technology Inc. (MTI) and Home Shopping Network (HSN). He has been an early stage investor, director and mentor for private companies that subsequently went public including MapInfo (now Pitney Bowes), META Group (now Gartner Group) and iRobot Corporation, where he served as a director from 1999 to 2016 and as lead director for the last 11 of those years. He served as a NYSE director from 1999 to 2004 and chaired its foundation. In the aftermathSponsoring Organizations of the 1987 stock market crash, he chairedTreadway Commission (COSO). Based on this assessment, management has concluded that the GroupCompany maintained effective internal control over financial reporting as of Thirty Committee to reform the Clearance and Settlement System. Mr. McNamee has been active as a director or trustee of civic organizations including The Albany Academies and Albany Medical Center, whose Finance Committee he chaired for a dozen years. He is also a director of several private companies, a Sterling Fellow of Yale University and a Trustee of The American Friends of Eton College. He conceived and co-authored the Tales of the Hoffman, which sold over 200,000 copies.  He received his Bachelor of Arts degree from Yale University. We believe Mr. McNamee’s qualifications to sit on our Board of Directors include his experience serving on countless boards, his background in investment banking and experience with the financial sector and its regulatory bodies.

Johannes M. Roth has been a director since April 2013. Mr. Roth is the founder and, since 2006, has been Managing Director and Chairman of FiveT Capital Holding AG, an investment holding companyDecember 31, 2017 based in Switzerland with businesses specializing in asset management, risk management and alternative investments. Since 2006, Mr. Roth has been a board member of FiveT Capital AG, Zürich, Switzerland, which advises several long-only funds and operates an asset management business for high net-worth individuals. We believe Mr. Roth’s qualifications to sit on our Board of Directors include his background in financial investments, financial and risk management and equity capital markets as well as his experience in management positions.

Xavier Pontone has been a director since October 2013. Since 2015, Mr. Pontone has been Vice President of Air Liquide Advanced Business and Technologies Europe, which develops new areas of growth for the Air Liquide Group.  Mr. Pontone is the Managing Director of Air Liquide Advanced Businesses based in Sassenage, France, since 2013.  He acts as Chairman of Fordonsgas AB, which is a company operating bio methane fueling stations in Sweden since 2014.  He is also Chairman of Copenhagen Hydrogen Newwork A/S, which is a company operating hydrogen fueling stations in Denmark since 2014.   Mr. Pontone sat on the board of directors of Hypulsion, the Company’s joint venture with Axane, S.A. (an Air Liquide subsidiary), through July 31, 2015.   As of August 1, 2015, the Company acquired 100% of Hypulsion, at which point Mr. Pontone was no longer a board member of Hypulsion.   Mr. Pontone also sits on the boards of Air Liquide Advanced Businesses and Technologies UK in the UK, Air Liquide Advanced Technologies Gmbh in Germany, Air Liquide Advanced Technologies in France, Societe des Taxis Electriques Parsiens in France, and Fonroch Biogas in France.    We believe Mr. Pontone’s qualifications to sit on our Board of Directors include his senior management experience in the hydrogen mobility and energy space in European markets.

Gregory L. Kenausis specified criteria.has been a director since October 2013. Mr. Kenausis is the founding partner and since 2005 has been the Chief Investment Officer of Grand Haven Capital AG, an investment firm, where he is the head of trading activity and research and is responsible for managing the fund’s structure. He is also an active board member of other boards of directors.  We believe Mr. Kenausis’s qualifications to sit on our Board of Directors include his background and senior level experience in financial investments, trading and management and equity capital markets.

Larry G. Garberding has served as a director of the Company since 1997. Mr. Garberding was a Director and Executive Vice President and Chief Financial Officer of DTE Energy Company and the Detroit Edison Company from 1990 until retiring in 2001. Mr. 

PART III

Item 10.  Directors, Executive Officers and Corporate Governance

(a)Directors

The information required under this item is incorporated herein by reference to the Company’s definitive proxy statement pursuant to Regulation 14A, which proxy statement will be filed with KPMG LLP, serving as partner from October 2004the Securities and Exchange Commission not later than 120 days after the close of the Company’s fiscal year ended December 31, 2017.

(b)Executive Officers

The information required under this item is incorporated herein by reference to September 2012,the Company’s definitive proxy statement pursuant to Regulation 14A, which proxy statement will be filed with the Securities and has a totalExchange Commission not later than 120 days after the close of 24 years of public accounting experience. Mr. Hull holds a Bachelorsthe Company’s fiscal year ended December 31, 2017.

(c)Code of Business Administration with a concentration in Accounting from the University of Notre Dame. Additionally, he is a Certified Public Accountant.Conduct and Ethics

Subject to any terms of any employment agreement with the Company (as described under Item 11 — EXECUTIVE COMPENSATION), each of the executive officers holds his or her respective office until the regular annual meeting of the Board of Directors following the Annual Meeting of Stockholders and until his or her successor is elected and qualified or until his or her earlier resignation or removal

(c)     CODE OF BUSINESS CONDUCT AND ETHICS

We have adopted a Code of Business Conduct and Ethics that applies to all officers, directors, employees and consultants of the Company. The Code of Business Conduct and Ethics is intended to comply with Item 406 of Regulation S-KS‑K of the Securities Exchange Act of 1934 and with applicable rules of The NASDAQ Stock Market, Inc. Our Code of Business Conduct and Ethics is posted on our Internet website under the “Investor Relations” page, under the

·                  AttractItem 12.  Security Ownership of Certain Beneficial Owners and retain talentedManagement and experienced executives;Related Stockholder Matters

·                  MotivateThe information required under this item is incorporated herein by reference to the Company’s definitive proxy statement pursuant to Regulation 14A, which proxy statement will be filed with the Securities and reward executives whose knowledge, skills and performance are critical to our success;Exchange Commission not later than 120 days after the close of the Company’s fiscal year ended December 31, 2017.

·                  Provide a competitive compensation package which is weighted towards pay-for-performance and in which total compensation is primarily determined by Company and individual results and the creation of shareholder value;SECURITIES AUTHORIZED FOR ISSUANCE UNDER EQUITY COMPENSATION PLANS

·                  Ensure fairness amongThe following table gives information as of December 31, 2017, about the executive management team by recognizingshares of Common Stock that may be issued upon the contributions each executive makes to our success; and

·                  Motivate our executives to manage our business to meet our short- and long-term objectives and reward them for meeting these objectives.

Independent Compensation Consultant

During 2014, Radford was retained as the Compensation Committee’s independent adviser to provide advisory services to aid the Compensation Committee in its oversightexercise of executive compensation. Radford did not perform any other services for the Company in 2014, 2015, or 2016. The Compensation Committee provided Radford with preliminary instructions regarding the goals of our compensation program and the parameters of the competitive review of executive compensation packages to be conducted by Radford. Radford was instructed to benchmark all components of compensation for all executive officer positions, including base salary, bonus and equity compensation. The Compensation Committee also instructed Radford to review the public disclosure by our peer companies concerning their executive compensation model and guidelines and compare them to our peer companies and actual compensation practices.

Our peer companies included the following:  Argan, Ballard Power Systems, Capstone Turbine, FuelCell Energy, PowerSecure International, OPOWER, Alliance Fiber Optic Products, Ambarella, CalAmp, Electronics for Imaging, Finisar, GT Advanced Technologies, Inphi, InvenSense, iRobot, Jive Software, Maxwell Technologies, Mercury Systems, Rambus, and Synaptics.

Our Executive Compensation Programs

Our executive compensation primarily consists of base salary, annual incentive bonuses, long-term equity incentive compensation and broad-based benefits programs. Consistent with the emphasis we place on pay-for-performance based incentive compensation, long-term equity incentive compensation in the form of stock options and restricted stock constitute a significant portion of our total executive compensation.

Within the context of the overall objectives of our compensation programs, our Compensation Committee determined the specific amounts of compensation to be paid to each of our executives in 2016 based on a number of factors, including:

·                  Its review of the report provided by Radford in 2014 showing the amount of compensation paid our peer companies to their executives with similar roles and responsibilities;

·                  Our executives’ performance during 2016 in general and as measured against predetermined performance goals;

·                  The nature, scope and level of our executives’ responsibilities;

·                  Our executives’ effectiveness in leadingunder the Company’s initiatives to increase customer value, productivity1999 Stock Option and revenue growth;

·                  The individual experience and skills of, and expected contributions from, our executives;

·                  The executive’s contribution to the Company’s commitment to corporate responsibility, including the executive’s success in creating a culture of unyielding integrity and compliance with applicable lawIncentive Plan, as amended (1999 Stock Option Plan), and the Company’s ethics policies;

·                  The amounts of compensation being paid to our other executives;

·                  The executive’s contribution to our financial results;

·                  Our executives’ historical compensation at our Company; and

·                  Any contractual commitments we have made to our executives regarding compensation.

Each of the primary elements of our executive compensation is discussed in detail below, including a description of the particular element and how it fits into our overall executive compensation.  Compensation paid to our named executive officers in 2016 is discussed under each element. In the descriptions below, we have identified particular compensation objectives which we have designed our executive compensation programs to serve; however, we have designed our compensation programs to complement each other and to collectively serve all of our executive compensation objectives described above. Accordingly, whether or not specifically mentioned below, we believe that, as a part of our overall executive compensation, each element to a greater or lesser extent serves each of our objectives.

Base Salary

We pay our executives a base salary which we review and determine annually. We believe that a competitive base salary is a necessary element of any compensation program designed to attract and retain talented and experienced executives. We also believe that attractive base salaries can motivate and reward executives for their overall performance. Base salaries are, in part, established based on the individual experience, skills, expected contributions of our executives, and our executives’ performance during the prior year.

After a review of 2015 base salaries, and in consideration of the recommendations made by Radford, the annual base salaries of our named executive officers for 2016 and 2015 were as follows: Mr. Marsh —$600,000 in 2016 and 2015; Mr. Middleton - $375,000 in 2016 and 2015; Mr. Schmid - $391,000 in 2016 and 2015; and Mr. Conway —$280,000 in 2016 and 2015, and Mr. Crespo - $220,000 in 2016 and 2015.  Our executives’ base salaries reflect the initial base salaries that we negotiated with each of our executives at the time of his or her initial employment or promotion and our subsequent adjustments to these amounts to reflect market increases, the growth and stage of development of our Company, our executives’ performance and increased experience, any changes in our executives’ roles and responsibilities, and other factors. The initial base salaries that we negotiated with our executives were based on our understanding of the market at the time, the individual experience and skills of, and expected contribution from, each executive, the roles and responsibilities of the executive, the base salaries of our existing executives, and other factors.

Annual Incentive Bonuses

Our named executive officers are eligible to receive annual incentive bonuses based on our pay-for-performance incentive compensation program. They are eligible to receive annual incentive bonuses primarily based upon their performance as measured against predetermined individual performance goals, including financial measures, achievement of strategic objectives, and other factors. The primary objective of this program is to motivate and reward our named executive officers for meeting individual performance goals. We do not believe that every important aspect of executive performance is capable of being specifically quantified in a predetermined performance goal. For example, events outside of our control may occur after we have established the named executive officers’ individual performance goals for the year that require our named executive officers to focus their attention on different or other strategic initiatives; thus, the individual performance goals may be modified during the fiscal year by the President and Chief Executive Officer, or the Board of Directors in the case of the President and Chief Executive Officer himself, to account for such events.

Within our pay-for-performance incentive compensation program, specific performance attainment levels are indicated for each performance goal. These performance attainment levels correlate to potential bonus award amounts that are calculated as a percentage of each executive’s base salary.

We established target and threshold attainment levels for each of our named executive officers based on a percentage of his or her base salary. For Mr. Marsh, the target and threshold levels were both set at 100% of his base salary. For Mr. Middleton and Mr. Schmid, the target and threshold levels were set at 100% and 65%, respectively, of their base salary. For Mr. Crespo, the target and threshold levels were set at 200% and 100%, respectively, of his base salary.  For Mr. Conway, the target and threshold levels were set at 75% and 30%, respectively, of his base salary.  Because the annual incentive bonuses are payable based on the achievement of each of several different performance goals, the executive officer may earn a bonus in an amount equal to between 0% and 100% (or 0% and 200% in the case of Mr. Crespo, and 0% and 75% in the case of Mr. Conway) of his base salary given his actual performance. If a performance goal is not met, then the executive does not earn the portion of the bonus award attributable to that objective. The threshold level for each performance goal is considered challenging for the executive to attain, and the executive would meet expectations if he achieved this level. The target attainment level is considered the maximum, or target, level for each performance goal because it is most challenging for the executive to attain, and the executive would need to exceed expectations to achieve this level. The threshold and target performance attainment levels are intended to provide for correspondingly greater or lesser incentives in the event that performance is within an appropriate range above or below the target performance attainment level.

In order to link each executive’s performance to corporate-wide strategy, the executives’ individual performance goals directly correlate to our corporate milestones, which are recommended by management and adopted or modified by the Board of Directors after appropriate consideration and review. The executives’ individual performance goals are determined in the same way as the corporate milestones such that management reviews how each executive may contribute to the corporate milestones and recommends individual performance goals to the Board of Directors. The Board of Directors, after appropriate consideration and review, approves or modifies the individual performance goals. For 2016, the individual performance goals, as well as the corporate milestones, included (i) annual product order targets, (ii) revenue, (iii) gross margins and (iv) operating cash flows. Each performance goal is given a relative weighting for each executive such that the achievement of (or failure to achieve) certain objectives has a greater impact on the potential bonus award. For 2016, the goals were weighted as follows for Messrs. Marsh, Middleton, Schmid, and Conway: order targets — 25%, revenue — 25%, gross margins — 25% and strategic initiatives — 25%.  For Mr. Crespo, the goals were weighted 50% towards order targets and 50% toward revenue.  Because disclosure of the specific individual performance goals would give competitors information that could be leveraged for competitive advantage, we do not disclose these specific individual performance goals or our executives’ actual performance against such goals.

After completion of the fiscal year, initially the Chief Executive Officer and other members of management, as appropriate, make a recommendation to the Compensation Committee of the Board of Directors for each executive’s potential bonus amount based on his level of attainment of each of his individual performance goals (with the exception of the Chief Executive Officer himself whose level of attainment is evaluated by the Compensation Committee directly). The Board of Directors, after review and discussion and recommendation from the Compensation Committee, determines the final level of attainment for each executive’s individual performance goals.

In 2016, Mr. Marsh earned a bonus of $300,000, or 50% of his annual base salary. Mr. Middleton earned a bonus of $187,500, or 50% of his annual base salary.  Mr. Schmid earned a bonus of $195,500, or 50% of his annual base salary. Mr. Crespo earned a bonus of $440,000, or 200% of his annual base salary.  Mr. Conway earned a bonus of $105,000, or 37.5% of his annual base salary.  Annual bonus awards made to the named executive officers in 2017 for performance in 2016 are reflected in the Non-Equity Incentive Plan Compensation column of the “Summary Compensation Table”.

Long-Term Equity Incentive Compensation

We grant long-term equity incentive awards in the form of stock options and restricted stock to executives as part of our total compensation package. Consistent with our emphasis on pay-for-performance based incentive compensation, these awards represent a significant portion of total executive compensation. Based on the stage of our Company’s development and the incentives we aim to provide to our executives, we have chosen to use either stock options or a combination of stock options and restricted stock as our long- term equity incentive awards. Our decisions regarding the amount and type of long-term equity incentive compensation and relative weighting of these awards among total executive compensation have also been based on our understanding of market practices of similarly situated companies and our negotiations with our executives in connection with their initial employment or promotion by our Company.

Additionally, the Board of Directors adopted stock ownership guidelines for executives, including the named executive officers, and these guidelines are also considered when granting long-term equity incentive awards to executives. The ownership guidelines provide a target level of Company equity holdings with which named executive officers are expected to comply within five (5) years or the date the individual is first appointed as an executive. The target stock holdings are determined as a multiple of the named executive officer’s base salary (5x for the Chief Executive Officer and 3x for the other named executive officers) and then converted to a fixed number of shares using a 200-day average stock price. The following shares count in determining compliance with the stock ownership guidelines: (i) shares owned outright by the executive or his or her immediate family members residing in the same household; (ii) shares held in the Plug Power Inc. Savings and Retirement Plan; (iii) restricted stock issued as part of an executive’s

annual or other bonus whether or not vested; (iv) shares acquired upon the exercise of employee stock options; (v) shares underlying unexercised employee stock options times a factor of thirty-three percent; and (vi) shares held in trust. The named executive officers who are required to be in compliance with the stock ownership guidelines are in compliance.

Stock option awards provide our executive officers with the right to purchase shares of our common stock at a fixed exercise price typically for a period of up to ten years, subject to continued employment with our Company. Stock options are earned on the basis of continued service and generally vest over three years, beginning with one-third vesting on the first anniversary of the grant date, one- third vesting on the second anniversary of the grant date and the final one-third vesting on the third anniversary of the grant date, subject to acceleration in certain circumstances. Stock option awards are made pursuant to our Amended and Restated 2011 Stock Option and Incentive Plan. Except as may otherwise be provided in the applicable stock option award agreement, stock option awards become fully exercisable upon a change of control. The exercise price of each stock option is the closing price of our common stock on the NASDAQ Capital Market as of the option grant date.Plan (2011 Stock Option Plan).

Grants to new hires and grants relating to an existing executive officer’s promotion may be made on a periodic basis. All grants to executive officers are approved by the

Equity Compensation Committee. We consider a number of factors in determining the number of stock options, if any, to grant to our executives, including:Plan Information

·                  the number of shares subject to,Item 13.  Certain Relationships and exercise price of, outstanding options, both vestedRelated Transactions, and unvested, held by our named executive officers;

·Director Independence                  the vesting schedule of the unvested stock options held by our named executive officers; and

·                  the amount and percentage of our total equity on a diluted basis held by our named executive officers.

Restricted stock awards provide our executive officers with a long-term incentive alternative to the stock option awards. Restricted stock awards vest subject to both continued employment of the executive by the Company and either time-based vesting or vesting based on satisfaction of specified performance objectives.

Broad-Based Benefits

All full-time employees, including our named executive officers, may participate in our health and welfare benefit programs, including medical, dental, and vision care coverage, disability insurance and life insurance, and our 401(k) plan.

Relationship of Executive Compensation to Risk

The Compensation Committee considers whetherinformation required under this item is incorporated herein by reference to the designCompany’s definitive proxy statement pursuant to Regulation 14A, which proxy statement will be filed with the Securities and Exchange Commission not later than 120 days after the close of the Company’s executive compensation program encourages senior executives to engage in excessive risk-taking. The Compensation Committee reviews the overall program design, as well as the balance between short-term and long-term compensation, the metrics used to measure performance and the award opportunity under the Company’s incentive compensation program, and the implementation of other administrative features designed to mitigate risk such as vesting requirements and stock ownership guidelines as described above. Based on its review, the Compensation Committee believes that the Company’s executive compensation program is aligned to the interests of stockholders, appropriately rewards pay for performance, and does not promote unnecessary and excessive risk.

Our Executive Compensation Process

The Compensation Committee of our Board of Directors is responsible for determining the compensation for our named executive officers. The Compensation Committee is composed entirely of non-employee directors who are “independent” as that term is defined in the applicable NASDAQ rules. In determining executive compensation, our Compensation Committee annually reviews the performance of our executives with our Chief Executive Officer, and our Chief Executive Officer makes recommendations to our Compensation Committee with respect to the appropriate base salary, annual incentive bonuses and performance measures, and grants of long-term equity incentive awards for each of our executives. The Chairman of the Compensation Committee makes recommendations to the Compensation Committee with regards to the Chief Executive Officer’s compensation. The Compensation Committee makes its determination regarding executive compensation and then recommends such determination to the Board of Directors. The Board of Directors ultimately approves executive compensation.

As a result, the total amount of compensation that we paid to our executives, the types of executive compensation programs we maintained, and the amount of compensation paid to our executives under each program has been determined by our Compensation Committee and Board of Directors based on their understanding of the market, experience in making these types of decisions, and judgment regarding the appropriate amounts and types of executive compensation to provide.

Compensation Committee Report

The Compensation Committee has reviewed the Compensation Discussion required by Item 402(b) of Regulation S-K and Analysis and discussed that analysis with Management. Based on its review and discussions with Management, the Compensation Committee recommended to our Board of Directors that the Compensation Discussion and Analysis be included in this Amendment. This report on executive compensation for is provided by the undersigned members of the Compensation Committee of the Board of Directors.

Gary K. Willis (Chairman)

George C. McNamee

Douglas Hickey

Compensation Committee Interlocks and Insider Participation

During 2016, Messrs. Willis (Chairman), McNamee and Hickey served as members of the Compensation Committee. None of them had any relationship with the Company requiring disclosure under applicable rules and regulations of the SEC.

Summary Compensation

The following table sets forth information concerning compensation for services rendered in all capacities awarded to, earned by or paid in the last three fiscal years to the Company’s named executive officers.

(1)         This column represents the dollar amount of the sign-on bonus paid to Mr. Middleton in 2014.

(2)         This column represents the aggregate grant date fair value of the stock award computed in accordance with FASB ASC Topic 718. Pursuant to SEC rules, the amounts shown exclude the impact of estimated forfeitures. Fair value is calculated using the closing price of Plug Power common stock on the date of grant. For additional information on stock awards, refer to note 14 of the Company’s consolidated financial statements in the Form 10-K for the year ended December 31, 2016, as2017.

Item 14.  Principal Accounting Fees and Services

The information required under this item is incorporated herein by reference to the Company’s definitive proxy statement pursuant to Regulation 14A, which proxy statement will be filed with the SEC. These amounts reflectSecurities and Exchange Commission not later than 120 days after the Company’s accounting expense, excluding the impact of estimated forfeitures, for these awards, and do not correspond to the actual value that will be recognized by the named executives.

(3)         This column represents the aggregate grant date fair value of the option award computed in accordance with FASB ASC Topic 718. Pursuant to SEC rules, the amounts shown exclude the impact of estimated forfeitures. For additional information on the valuation assumptions with respect to option awards, refer to note 14close of the Company’s consolidated financial statements in the Form 10-K for thefiscal year ended December 31, 2016, as filed with the SEC. These amounts reflect the Company’s accounting expense, excluding the impact2017.

PART IV

(4)Item 15.  Exhibits and Financial Statement Schedules         This column represents the dollar amount of bonuses expected to be paid to executives under our non-equity plan.

(5)         Includes the Company’s share of contributions on behalf of Mr. Marsh to the Plug Power 401(k) savings plan in the amount of $13,250, $13,250 and $13,250, in the years ended 2016, 2015 and 2014, respectively, and payments of $500, $500, and $516 for supplemental life insurance premiums in each of the years ended December 31, 2016, 2015 and 2014, respectively.

(6)         Mr. Middleton was hired as Chief15(a)(1) Financial Officer and Senior Vice President effective December 1, 2014.

(7)         Includes the Company’s share of contributions on behalf of Mr. Middleton to the Plug Power 401(k) savings plan in the amount of $13,250, 13,250 and $1,441 in the years ended December 31, 2016, 2015 and 2014, respectively, payment of $500, $500 and $180 for supplemental life insurance premiums in the years ended December 31, 2016, 2015 and 2014, respectively, and payment of $27,000 and $127,889 for moving and relocation expenses in the years ended December 31, 2015 and 2014.

(8)         Mr. Crespo became a named executive officer effective January 1, 2015.

(9)         Includes the Company’s share of contributions on behalf of Mr. Crespo to the Plug Power 401(k) savings plan in the amount of $13,250, $13,250 in the years ended December 31, 2016 and 2015, and payment of $500 and $500 for supplemental life insurance in the years ended December 31, 2016 and 2015.

(10)  Includes the Company’s share of contributions on behalf of Mr. Schmid to the Plug Power 401(k) savings plan in the amount of $13,250,  $13,250, and  $13,250, in the years ended December 31, 2016,  2015, and 2014, respectively, and payment of $500, $500,  and  $276, for supplemental life insurance premiums for the years ended December 31, 2016, 2015, and 2014, respectively, and payment of $38,706 for moving and relocation expenses for the year ended December 31, 2014.

(11)  Includes the Company’s share of contributions on behalf of Mr. Conway to the Plug Power 401(k) savings plan in the amount of $13,250, $13,250 and $13,250 in the years ended December 31, 2016, 2015 and 2014, respectively, payments of $500, $500, and $276 for supplemental life insurance premiums in each of the years ended December 31, 2016, 2015, and 2014, respectively.

Grants of Plan-Based Awards