Advancing Commercial Opportunities: Project New Horizon Collaboration with Salt River Project and Google, Large Capacity Energy Storage System for the U.S. Department of the Air and Space Force, Strategic Partnership with Alsym, Successful Commissioning of LDES at TID

Burbank Water and Power/APPA Efficacy Report Provides Validates ESS Iron Flow Technology; VoltStorage GmbH Assets Acquisition Strengthens Technology Platform and Intellectual Property Base

Strengthened Liquidity Position Supports Execution Across Energy Base Development, Commercial Execution and Go-to-Market Priorities

Management to Host Webcast and Conference Call Today at 5:00 p.m. ET

WILSONVILLE, Ore.--(BUSINESS WIRE)--May 7, 2026-- ESS Tech, Inc. (“ESS,” “ESS, Inc.” or the “Company”) (NYSE: GWH), a leading manufacturer of long-duration energy storage systems (“LDES”) for commercial and utility-scale applications, today announced financial results for its first quarter ended March 31, 2026.

“The first quarter and second quarter to date reflect continued initiatives to reset ESS around execution, capital discipline, and scalable commercial opportunities,” said Drew Buckley, Chief Executive Officer of ESS. “We continued to strengthen our leadership team, improve our financial position, and sharpen our operating focus as we advance into the Company’s next phase. We advanced Project New Horizon with Salt River Project and Google, were awarded a $9.9 million contract with Concurrent Technologies Corporation (“CTC”) and the United States Air Force Research Laboratory (“AFRL”) for a large capacity energy storage system, recently announced our partnership with Alsym Energy, and added commercial leadership with the appointment of Randy Selesky as Chief Commercial Officer.

“On the technology side, the final report issued in connection with Burbank Water and Power for the American Public Power Association (“APPA”) to evaluate the application of ESS’s Iron Flow Battery technology in a real-world utility environment. The report concluded that ESS’s Iron Flow Battery technology works as intended and there is a use case for this battery technology in a utility’s overall energy storage strategy. We believe that our acquisition of VoltStorage GmbH’s assets has strengthened and expanded our intellectual property base and technology platform.

“Looking ahead, we expect commercial activity to increase as projects progress from contracting to delivery and commissioning, supported by an active pipeline across targeted end markets. Recent progress reinforces what we believe is growing demand for resilient, domestically produced long-duration energy storage, and we believe our commercial and technology momentum better positions ESS to convert growing demand for safe, long-duration, American-made energy storage into meaningful commercial progress.”

First Quarter 2026 and Subsequent Highlights

• Final report issued by Burbank Water and Power for the American Public Power Association concluded that ESS’s Iron Flow Battery technology works as intended and there is a use case for this battery technology in a utility’s overall energy storage strategy.
• Successfully commissioned two ESS Iron Flow battery systems at Turlock Irrigation District (“TID”) in California’s Central Valley, pairing ESS Iron Flow battery technology with solar panels, designed to generate renewable electricity while helping reduce water evaporation.
• Signed a letter of intent for a strategic partnership with Alsym Energy, a pioneer in non-flammable, high performance sodium-ion batteries, to develop next generation battery solutions designed to address use cases traditionally served by lithium-ion systems but without the inherent thermal runaway risks associated with lithium chemistries.
• Engaging with international investor relations specialists MZ Group to lead a comprehensive strategic investor relations and financial communications program across all key markets.
• Announced a collaboration framework with Salt River Project and Google for Project New Horizon at SRP’s Copper Crossing Energy and Research Center in Florence, Arizona. The 5 MW / 50 MWh pilot will deploy ESS’s Energy Base technology. Manufacturing is expected to begin in 2026 and delivery is targeted for December 2027.
• Appointed Randall Selesky as Chief Commercial Officer to lead global commercial strategy, sales, marketing, product management, and business development. Mr. Selesky brings more than 20 years of leadership in the energy sector, including more than a decade in the battery storage industry and previously served as Chief Commercial Officer at VoltStorage.
• Acquired the intellectual property and assets of VoltStorage GmbH, adding VoltStorage's patents, technical development work, and key personnel to ESS’s existing platform.
• Closed $15 million registered direct offering at $1.75 per share, which was a premium to the January 28, 2026 closing price. The financing is intended to support general corporate purposes and working capital.
• Awarded a $9.9 million contract with Concurrent Technologies Corporation and the United States Air Force Research Laboratory for a large capacity energy storage system of up to 27 MWh to support U.S. operations.
• Announced leadership changes naming Drew Buckley as Chief Executive Officer, Kelly Goodman as Chief Strategy Officer and General Counsel, and Kate Suhadolnik as Chief Financial Officer as the Company continued its leadership and organizational reset focused on governance, execution, and financial discipline.

First Quarter 2026 Financial Highlights

• Revenue was $128 thousand for the three months ended March 31, 2026, compared with $0.6 million in the prior-year period due to fewer deliveries of equipment to customers.
• Total operating expenses decreased 33% to $6.7 million for the three months ended March 31, 2026, compared with $10.0 million in the prior-year period. The decrease was primarily due to a decrease in sales and marketing expenses of $1.7 million, and a decrease in general and administrative expenses of $1.7 million, reflecting our ongoing commitment to reduce sales and marketing and general administrative expenses as part of our efforts to prioritize investment in our product development.
• Net loss improved to $(15.9) million, or $(0.54) per share, for the three months ended March 31, 2026, compared with $(18.0) million, or $(1.50) per share, in the prior-year period.
• Adjusted EBITDA loss improved 31% year-over-year to $(10.3) million for the three months ended March 31, 2026 compared to $(15.0) million for the three months ended March 31, 2025.
• Net cash used in operating activities was $13.5 million for the three months ended March 31, 2026, compared with $18.2 million in the prior-year period.
• Unrestricted cash and cash equivalents were $15.5 million as of March 31, 2026, and short-term investments were $6.0 million, representing total liquidity of $21.5 million.

Kate Suhadolnik, Chief Financial Officer of ESS, commented, “We remain focused on expense control, liquidity, and maintaining financial flexibility as we support the business through its transition and commercialization efforts. Total operating expenses declined 33% year-over-year and we also benefited from the capital raised through our registered direct offering during the quarter. We ended the quarter with $15.5 million in unrestricted cash and cash equivalents and $6.0 million in short-term investments, representing total liquidity of $21.5 million. We remain focused on the strategic allocation of capital as we advance our operational and commercialization priorities.”

Conference Call Details

ESS Chief Executive Officer Drew Buckley and Chief Financial Officer Kate Suhadolnik will host the conference call, followed by a question-and-answer period. The call will be accompanied by a presentation, which will be available following the call via the investor relations section of the Company’s website.

To access the call, please use the following information:

The replay can be viewed through the webcast link above and the presentation utilized during the call will be available via the investor relations section of the Company's website.

About ESS, Inc.

ESS (NYSE: GWH) is the leading manufacturer of long-duration iron flow energy storage solutions. ESS was established in 2011 with a mission to accelerate decarbonization safely and sustainably through longer lasting energy storage. Using easy-to-source iron, salt, and water, ESS iron flow technology enables energy security, reliability and resilience. We build flexible storage solutions that allow our customers to meet increasing energy demand without power disruptions and maximize the value potential of excess energy. For more information visit www.essinc.com.

Use of Non-GAAP Financial Measures

In this press release and the accompanying earnings call, ESS includes Adjusted EBITDA, which is a non-GAAP performance measure that ESS uses to supplement its results presented in accordance with U.S. GAAP. As required by the rules of the Securities and Exchange Commission (“SEC”), ESS has provided herein a reconciliation of the non-GAAP financial measures contained in this presentation and the accompanying earnings call to the most directly comparable measures under GAAP. ESS’ management believes Adjusted EBITDA is useful in evaluating its operating performance and is a similar measure reported by publicly-listed U.S. companies, and regularly used by securities analysts, institutional investors, and other interested parties in analyzing operating performance and prospects. By providing this non-GAAP measure, ESS’ management intends to provide investors with a meaningful, consistent comparison of ESS’ profitability for the periods presented. Adjusted EBITDA is not intended to be a substitute for net income/loss or any U.S. GAAP financial measure and, as calculated, may not be comparable to other similarly titled measures of performance of other companies in other industries or within the same industry.

ESS defines and calculates Adjusted EBITDA as net loss before interest expense (income), net, stock-based compensation, depreciation and amortization, loss (gain) on revaluation of common stock warrant liabilities, financing costs and other income, net as they are not indicative of business operations.

Forward-Looking Statements

This communication contains forward-looking statements (including within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended, and Section 27A of the Securities Act of 1933, as amended) concerning the Company and other matters that involve substantial risks and uncertainties. These statements may discuss the management team's goals, beliefs, hopes, intentions and expectations as to future plans, trends, events, results of operations and financial condition and the related potential effects on ESS, or otherwise, based on current beliefs of the management of the Company, as well as assumptions made by, and information currently available to, the Company's management. These forward-looking statements can be identified by the use of forward-looking terminology, including the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intends,” “may,” “might,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “will,” “would,” or, in each case, their negative or other variations or comparable terminology may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. These forward-looking statements, which are subject to risks, uncertainties and assumptions about us, may include projections of our future financial performance, our anticipated growth strategies and anticipated trends in our business. Examples of forward-looking statements include, among others, statements pertaining to statements made by the Company’s Chief Executive Officer and Chief Financial Officer, statements pertaining to the Company’s 2026 outlook and beyond, cash position, the potential and capabilities of the Company’s technology and platform, advancement of operational and commercialization priorities, the Company’s ability to execute on Project New Horizon, including the timing for manufacturing and delivery for Project New Horizon, as well as statements regarding the Company’s partnerships, employees, commercial expectations regarding sales order and pipeline, the expected integration of the VoltStorage intellectual property and technology, ESS product development and manufacturing, and relationships with customers. Many factors could cause actual future events to differ materially from the forward-looking statements in this communication. There can be no assurance that the future developments affecting ESS will be those that we have anticipated. These forward-looking statements involve a number of risks, uncertainties (some of which are beyond ESS control) or other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements, which include, but are not limited to: barriers we face in our attempts to produce our energy storage products; risks related to the Company’s ability to execute and meet timelines related to Project New Horizon; our products being in the early stage of commercialization and aspects of our technology not having been fully field tested; our inability to develop our business and effectively commercialize our energy storage products; our dependence on third-party suppliers;; our ability to secure or maintain long-term supply relationships with critical suppliers; delays, disruptions or quality control problems in our manufacturing operations; our ability to adequately control our costs, effectively scale our operations and achieve our cost reduction strategy; our reliance on complex machinery; our ability to increase our production capacity; product recalls, defects or performance problems with our products; required maintenance being performed incorrectly or maintenance requirements exceeding our current expectations; our history of losses; our ability to continue as a “going concern”; our ability to secure binding orders; failure to deliver the benefits offered by our technology; inability to achieve market acceptance of our products; our ability to sell effectively to large customers; failure to accurately estimate future supply and demand for our products and services; failure to manage our growth effectively; failure to meet the obligations under our sales contracts and service agreements; our ability to complete on schedule and within budget; loss of a member of our senior management or other key personnel; changes to our leadership team; expansions into new markets, product lines or services; our warranty obligations; failure to identify or complete commercial or financial transactions; changes in the global trade environment; our projects relationships with related parties; regulatory challenges; our ability to protect our intellectual property; and our ability to raise capital in the near future; general economic and market conditions as well as geopolitical developments and other risks and uncertainties described more fully in the section titled “Risk Factors” in the Company's Annual Report on Form 10-K filed on March 5, 2026 and the Company's other filings with the U.S. Securities and Exchange Commission. Except as required by law, ESS is not undertaking any obligation to update or revise any forward-looking statements whether as a result of new information, future events or otherwise.

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Company
investors@essinc.com

Investor Relations
Chris Tyson
Executive Vice President
MZ Group - MZ North America
Phone: (949) 491-8235
GWH@mzgroup.us
www.mzgroup.us

Source: ESS, Inc.