Author: [email protected]

WILSONVILLE, Ore., August 6, 2026 – ESS Tech, Inc. (NYSE: GWH) (“ESS” or the “Company”), a leading provider of energy storage solutions, today announced the signing of a non-binding Letter of Intent (the “LOI”) for a proposed business combination with a private company in the energy sector (the “Counterparty”). The opportunistic transaction reflects the hallmarks of ESS’ core business strategy: Make energy solutions that can deliver in the era of speed to power.

The Counterparty identity and the additional commercial terms of the proposed transaction remain confidential pending the completion of due diligence and the negotiation and execution of definitive transaction documents. ESS anticipates announcing a final agreement by the end of September 2026 and is targeting a close before year-end. ESS expects to continue to advance the existing technology platform during this period.

“ESS’ continued exploration of strategic opportunities has allowed us to identify a potential transaction that we believe may support the Company’s long-term objectives,” said Drew Buckley, Chief Executive Officer. “We approached our review of this proposed transaction thoughtfully and with an aim to maximize shareholder value, and we believe that this business combination achieves that. We look forward to working toward definitive agreements in the period ahead.”

The LOI is non-binding and does not obligate either party to consummate the proposed transaction. Completion of the proposed transaction remains subject to, among other things, satisfactory completion of due diligence, the negotiation and execution of definitive agreements, and the receipt of all required board, stockholder, and regulatory approvals, including compliance with applicable listing requirements. There can be no assurance that definitive agreements will be executed or that the proposed transaction will be completed in the terms described, or at all. The Company does not intend to provide further updates regarding the proposed transaction unless and until it determines that additional disclosure is required or appropriate.

Additional Information and Where to Find It

In connection with the proposed business combination (the “Proposed Transaction”), and depending on the final structure of the Proposed Transaction, ESS Tech, Inc. (“ESS”) expects to file with the Securities and Exchange Commission (the “SEC”) a registration statement on Form S-4 (as may be amended, the
“Registration Statement”), which would include a preliminary proxy statement of ESS and a prospectus (the “Proxy Statement/Prospectus”). Alternatively, ESS may file a standalone proxy statement. In either case, the definitive proxy statement (or definitive Proxy Statement/Prospectus) and other relevant documents will be mailed to ESS’s stockholders as of a record date to be established for voting on the Proposed Transaction and any other matters as described in the Proxy Statement/Prospectus. ESS may also file other documents regarding the Proposed Transaction with the SEC. This press release does not contain all of the information that should be considered concerning the Proposed Transaction and is not intended to form the basis of any investment, voting or any other decision in respect of the Proposed Transaction. BEFORE MAKING ANY VOTING OR INVESTMENT DECISION, INVESTORS AND STOCKHOLDERS OF ESS AND OTHER INTERESTED PARTIES ARE URGED TO READ, WHEN AVAILABLE, THE PRELIMINARY PROXY STATEMENT/PROSPECTUS AND ANY AMENDMENTS THERETO, AND THE DEFINITIVE PROXY STATEMENT/PROSPECTUS AND ALL OTHER RELEVANT DOCUMENTS FILED OR THAT WILL BE FILED WITH THE SEC IN CONNECTION WITH ESS’s SOLICITATION OF PROXIES FOR THE SPECIAL MEETING OF ITS STOCKHOLDERS TO BE HELD TO APPROVE THE PROPOSED TRANSACTION AND OTHER MATTERS AS DESCRIBED IN THE PROXY STATEMENT/PROSPECTUS BECAUSE THESE DOCUMENTS WILL CONTAIN IMPORTANT INFORMATION ABOUT ESS, THE COUNTERPARTY, THE COMBINED COMPANY AND THE PROPOSED TRANSACTION. Investors and security holders will be able to obtain free copies of the Registration Statement and the Proxy Statement/Prospectus (when available) and all other documents filed or that will be filed with the SEC by ESS, the Counterparty or the combined company without charge, once available, on the SEC’s website at www.sec.gov.

NEITHER THE SEC NOR ANY STATE SECURITIES REGULATORY AGENCY HAS APPROVED OR DISAPPROVED THE PROPOSED TRANSACTION DESCRIBED HEREIN, PASSED UPON THE MERITS OR FAIRNESS OF THE PROPOSED TRANSACTION OR ANY RELATED TRANSACTIONS OR PASSED UPON THE ADEQUACY OR ACCURACY OF THE DISCLOSURE IN THIS PRESS RELEASE. ANY REPRESENTATION TO THE CONTRARY CONSTITUTES A CRIMINAL OFFENSE.

Participants in the Solicitation

ESS, the Counterparty and their respective directors and executive officers may be deemed under SEC rules to be participants in the solicitation of proxies from ESS’s stockholders in connection with the Proposed Transaction. A list of the names of ESS’s directors and executive officers and information regarding their interests in the Proposed Transaction and their ownership of ESS securities are, or will be, contained in ESS’s filings with the SEC, including the Proxy Statement/Prospectus relating to the Proposed Transaction. Additional information regarding the persons who may, under SEC rules, be deemed participants in the solicitation of ESS’s stockholders in connection with the Proposed Transaction, including the names and interests of ESS’s and the Counterparty’s directors and executive officers, will be set forth in the Proxy Statement/Prospectus relating to the Proposed Transaction when it is filed with the SEC. Investors and security holders may obtain free copies of these documents as described above.

No Offer or Solicitation

This press release is for informational purposes only and is not a proxy statement or solicitation of a proxy, consent or authorization with respect to any securities or in respect of the Proposed Transaction, and shall not constitute an offer to sell or exchange, or the solicitation of an offer to buy or exchange, any securities of ESS, the Counterparty or the combined company, or any commodity or instrument or related derivative, nor shall there be any sale of any such securities in any state or jurisdiction in which such offer, solicitation, sale or exchange would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction. No offer of securities shall be made except by means of a prospectus meeting the requirements of the Securities Act of 1933, as amended (the “Securities Act”), or an exemption therefrom. Investors should consult with their counsel as to the applicable requirements for a purchaser to avail itself of any exemption under the Securities Act.

Forward-Looking Statements 

This communication contains forward-looking statements (including within the meaning of Section 21E of the 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,” “intend,” “may,” “might,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “will,” “would,” or, in each case, their negative or other variations or comparable terminology, 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 ESS and the combined company’s future financial performance, anticipated growth strategies and anticipated trends. Examples of forward-looking statements include, among others, statements regarding the parties entering into definitive documentation with respect to, and the closing of, the Proposed Transaction and the timing of the Proposed Transaction, including the date ESS anticipates announcing a definitive agreement and the closing date of the Proposed Transaction; statements regarding potential benefits of the Proposed Transaction; statements regarding certain filings the parties expect to make with the SEC in connection with the Proposed Transaction, including statements regarding the filing of the preliminary and definitive proxy statement to solicit votes of ESS’s stockholders; statements regarding the combined business; statements regarding ESS’s ability to advance the existing technology platform; statements by ESS’s Chief Executive Officer; and statements of assumptions underlying other statements. You are cautioned not to rely on these forward-looking statements. Any forward-looking statements speak only as of the date of this press release and are qualified in their entirety by the cautionary statements contained herein. There can be no assurance that the LOI will result in the execution of definitive agreements or that the Proposed Transaction will be consummated on the terms described, on the anticipated timeline, or at all. Both ESS and the Counterparty can terminate the LOI at any time. These statements are based on current expectations of future events and thus are inherently subject to uncertainty. If underlying assumptions prove inaccurate or known or unknown risks or uncertainties materialize, actual results could vary materially from ESS and the Counterparty’s expectations and projections. These risks, uncertainties, and other factors include: the non-binding nature of the LOI and the parties’ ability to complete due diligence and to negotiate and execute definitive transaction agreements on the anticipated timeline or at all; the parties’ ability to satisfy the conditions to, and to consummate, the Proposed Transaction, including obtaining required regulatory approvals and the approval of ESS’s stockholders; the ability of the combined company to realize the anticipated benefits of the Proposed Transaction; risks relating to the integration of the two businesses and higher than anticipated transaction and integration costs; difficulties and delays in integrating the combined business resulting from the Proposed Transaction; the combined company’s ability to access additional capital on acceptable terms; the ability of the combined business to retain key customers, employees and relationships; the parties’ ability to raise additional capital to fund the combined company’s business plan; cash flow and access to capital; decline in demand for the combined company’s products; and conditions in the debt and equity capital markets; 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, subsequent Quarterly Reports on Form 10-Q, subsequent Current Reports on Form 8-K 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.

About ESS Tech, Inc.

ESS (NYSE: GWH) is the leading provider of non-lithium 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 materials, ESS solutions enable 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.

Contacts

Investor Relations
Chris Tyson
Executive Vice President
MZ Group – MZ North America
Phone: (949) 491-8235
[email protected]
www.mzgroup.us

Media
Brad Dore
VP, Marketing
ESS Tech, Inc.
Phone: (916) 207-7355
[email protected]

New Non-Lithium Platform Expands ESS Technology Portfolio, Addressable Market for U.S.-Based Company

WILSONVILLE, Ore – July 8, 2026 – ESS Tech, Inc. (NYSE: GWH) (“ESS” or the “company”), a leading provider of non-lithium energy storage solutions, today announced the launch of the ESS Bridge™, a modular sodium-ion battery energy storage system (BESS) designed for utilities, AI-driven data centers, critical infrastructure operators, and commercial and industrial customers seeking superior alternatives to conventional lithium-ion technologies.

The introduction of Bridge marks a significant milestone in ESS’s strategy to become a leading provider of U.S.-made, non-lithium energy storage solutions spanning short-, medium-, and long-duration applications.

The Bridge name reflects the platform’s role in connecting energy generation and consumption while bridging the gap between today’s energy needs and a more secure and resilient energy future.

The release follows ESS’s recent news that it has generated more than $1 billion in early-stage customer opportunities since announcing its sodium-ion market entry, reflecting growing demand for safer energy storage technologies that can meet the power needs of AI data centers and other critical infrastructure.

“Bridge is how we meet the demand we’re already seeing,” said Drew Buckley, CEO of ESS. “AI workloads are reshaping what data centers need from energy storage, and sodium-ion handles those power needs more effectively than conventional technologies. Bridge is built to deliver that, which is why we’ve generated nearly a billion dollars in early-stage opportunity since entering sodium-ion.”

Bridge is a 1.2 MWh building-block AC battery system that combines advanced sodium-ion technology with ESS’s expertise in system integration, controls, energy management, and project execution. With the solution, ESS provides complete system integration, including battery cells, modules, racking, power conversion, cabling, and battery management system (BMS) hardware and software in a 10-foot container. ESS is also providing an energy management system (EMS) to enable plant-level monitoring, optimization, and control.

The plug-and-play unit simplifies logistics, can be installed with a heavy-duty forklift and can operate in myriad environments with simple air cooling. The modular blocks are stackable, delivering up to 4.8 MWh of storage capacity in the same footprint as a traditional 20-foot battery container, maximizing site utilization. The building block system scales easily to support both commercial and large, utility-scale applications.

Unlike conventional lithium-ion systems, Bridge is designed to eliminate the risk of fire from thermal runaway and requires no complex HVAC or liquid cooling systems, reducing operational complexity, maintenance requirements, and total cost of ownership. It is capable of a wide range of charge and discharge profiles, from 1 to 16 hours or more depending on configuration.

Engineered for demanding environments, Bridge is designed to reliably provide power in environments from -40° C to 50° C with a 20-year operating design life, helping owners avoid costly battery replacement and risky augmentation cycles.

Built around abundant, widely available materials, Bridge is designed to leverage an emerging alternative supply chain to conventional lithium-ion batteries, reducing exposure to constrained critical minerals and geopolitical sourcing risks. The solution supports the development of a future domestic energy storage supply chain while helping customers manage exposure to Foreign Entities of Concern (FEOC).

“Today’s battery asset owners are looking for solutions that improve upon the conventional model,” said Randall Selesky, Chief Commercial Officer, ESS. “They want systems that improve safety, simplify operations, provide flexibility and support long-term energy security objectives. Bridge is designed to deliver those benefits in a single platform.”

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, 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 our anticipated growth strategies and anticipated trends in our business. Examples of forward-looking statements include, among others, ESS’ plans for its business, ESS’ potential opportunities that approach $1 billion for sodium-ion product, the demand for non-lithium and domestic battery solutions, the timeline for ESS’ development of the Bridge product, power demands and energy storage, domestic supply chain availability, statements by ESS’ CEO, and ESS’ ability to grow and our ability to meet the growing demand for energy storage. These forward-looking statements are based on ESS’ current expectations and beliefs concerning future developments and their potential effects on ESS. 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, the demand for our Bridge product not developing as anticipated; our ability to realize and capitalize on sodium-ion opportunities; delays in the development of the Bridge product; our ability to expand our portfolio; 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; our ability to secure or maintain a domestic supply chain; 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; expansions into new markets, product lines or services; and our ability to raise capital in the near future and other risks and uncertainties described more fully in Exhibit 99.2 of the Current Report on Form 8-K filed by the Company on June 23, 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.

Contacts

Company
[email protected]

Investor Relations
Chris Tyson
Executive Vice President
MZ Group – MZ North America
Phone: (949) 491-8235
[email protected]
www.mzgroup.us

Media
Brad Dore
VP, Marketing
ESS Tech, Inc.
Phone: (916) 207-7355
[email protected]

Company Aligns Resources to Support Expanded Focus on AI Infrastructure and Data Center Markets

WILSONVILLE, Ore – June 23, 2026 – ESS Tech, Inc. (NYSE: GWH) (“ESS” or the “company”), a leading provider of non-lithium energy storage solutions, today announced strong early customer engagement for its planned U.S.-made sodium-ion battery energy storage system (BESS) offering, focused on short- and medium-duration applications that have historically been served by lithium-ion systems.

 Since announcing its letter of intent with Alsym Energy seven weeks ago, ESS has generated significant customer interest for sodium-ion solutions across data centers, critical infrastructure, and utility markets, exceeding demand expectations with limited outbound marketing. The company has now developed early-stage opportunities approaching $1 billion for its sodium-ion solutions and is accelerating development of its sodium-ion BESS platform to meet growing near-term demand for safer, domestically sourced energy storage solutions.

 “The demand we’re seeing for sodium-ion is unlike anything in our company’s history,” said Drew Buckley, Chief Executive Officer of ESS. “Energy demand is changing faster than the market can respond, and it’s clear the solutions of the past won’t fill the gap. We’re moving decisively to meet that need, accelerating our path towards near-term revenue while establishing the foundation to deliver at the scale and speed the market needs.”

Across the power sector, including hyperscalers and fast-growing data centers, customers are racing to secure storage that is safe, fast to deploy, and free of supply chain risk. They need systems that avoid the fire and insurance exposure of lithium-ion, meet aggressive delivery timelines, and eliminate Foreign Entity of Concern exposure. Sodium-ion is uniquely suited to fill that gap: it virtually eliminates thermal runaway risk and uses abundant, domestically available materials rather than constrained lithium supply chains.

The company will continue development of its iron flow battery technology for long-duration applications while streamlining its Wilsonville operations, reducing expenses and cash burn, to reallocate capital toward the sodium-ion and related solutions with greater near-term revenue potential.

 ESS soon plans to announce sodium-ion container, rack, and hardware solutions, as well as digital software offerings to optimize battery and system health, to support the customer opportunities.

“This transition enables ESS to pursue attractive market opportunities while maintaining our commitment to long-term innovation,” added Buckley. ” We believe ESS is well-positioned to create value for customers and shareholders by focusing our organization on high-growth markets with a differentiated technology, leveraging our proven execution capabilities, and continuing to deliver American-made energy storage solutions.” 

About ESS Tech, Inc.

ESS (NYSE: GWH) is the leading provider of non-lithium 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 materials ESS solutions enable 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.

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, 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 our anticipated growth strategies and anticipated trends in our business. Examples of forward-looking statements include, among others, ESS’ plans for its business, ESS’ potential opportunities that approach $1 billion in sodium-ion opportunities, the demand for non-lithium battery solutions, the timeline for ESS’ development of sodium-ion BESS, power demands and energy storage, ESS’ ability to generate near-term revenue and reduce its expenses, statements by ESS’ CEO, and ESS’ ability to grow and our ability to meet the growing demand for energy storage. These forward-looking statements are based on ESS’ current expectations and beliefs concerning future developments and their potential effects on ESS. 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, the demand for our sodium-ion BESS not developing as anticipated; our strategy to allocate resources toward sodium-ion BESS not achieving the anticipated benefits and adversely affecting the development of our iron flow battery technology; our ability to generate revenue, including in the near-term; our cash burn and cash runway; our ability to realize and capitalize on sodium-ion opportunities; delays in the development of our sodium-ion BESS; our ability to expand our portfolio; our 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 Exhibit 99.2 of the Current Report on Form 8-K filed by the Company on June 23, 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.

Contacts

Investor Relations
Chris Tyson
Executive Vice President
MZ Group – MZ North America
Phone: (949) 491-8235
[email protected]
www.mzgroup.us

Media
Brad Dore
VP, Marketing
ESS Tech, Inc.
Phone: (916) 207-7355
[email protected]

Next Generation Sodium-ion Battery Solution Enables ESS Transition to a Full- Service BESS Platform Provider for Expanded Applications

Partnership Enables ESS to Enter the Short and Medium Duration Energy Storage Segment

Wilsonville, Ore. and Malden, MA — April 29, 2026 — ESS Tech, Inc., a leading manufacturer of sustainable, long-duration energy storage systems (“LDES”), today announced the signing of a letter of intent for a strategic partnership with Alsym Energy, a pioneer in non-flammable, high-performance
sodium-ion batteries, to add 8.5 GWh of sodium-ion cells and modules to its portfolio.

This next-generation battery solution is designed to address use cases traditionally served by lithium-ion systems – and those where lithium cannot go – but without the inherent thermal run-away risks associated with lithium chemistries.

This partnership marks ESS’s entry into the short- and medium-duration BESS (“Battery Energy Storage System”) segment, a market historically dominated by lithium-ion. It meaningfully expands the Company’s addressable market beyond its established position in long-duration storage. The Alsym sodium-ion technology virtually eliminates thermal runaway risk and lowers total cost of ownership. In addition, the solution does not require complex HVAC systems, demonstrates high round trip efficiency, employs fast charge and discharge capabilities and offers a simpler, safer deployment profile for customers seeking superior stationary storage solutions.

“Sodium-ion and iron flow are complementary technologies,” said Drew Buckley, Chief Executive Officer of ESS. “Alsym’s sodium-ion Na-Series is an ideal solution for ESS’s short- and medium-duration applications where high power, fast cycling, and rapid response are paramount. ESS’s existing Energy Base® iron flow platform is engineered for the 8–24 hour long-duration segment, where deep daily cycling,25-year asset life, and zero capacity degradation deliver the lowest levelized cost of storage. Together, the two chemistries form a unified, non-lithium platform that enables ESS to meet customers’ full storage needs from a single trusted provider, whether the application calls for firming renewables over a few hours, shifting energy across a full day, or pairing both within a single project to optimize economics across the full duration curve.”

Randall Selesky, Chief Commercial Officer at ESS, added, “This partnership represents a major milestone in our strategy to become a full-spectrum, non-lithium solutions provider for the entire energy storage market with safer, more sustainable technologies. By combining Alsym’s high performance, nonflammable sodium-ion technology with ESS’ systems expertise and Energy Base® long-duration solutions, we are giving customers a clear pathway beyond lithium-ion — without compromising performance or economics.

“Unlike lithium-ion batteries and many other sodium-ion batteries, Alsym’s Na-Series batteries are non-combustible and thermally stable, reducing system complexity, improving safety, and lowering total cost of ownership by reducing the need for extensive fire suppression and HVAC infrastructure. Alsym’s Na-Series has been developed using a proprietary, physics-informed AI platform for battery development that dramatically shortens the time to bring innovation to the market. The batteries utilize non-foreign entity of concern (“FEOC”) sourced materials and provide integrators and OEMs with a safe, cost-effective, supply-secure battery solution,” Selesky concluded.

Mukesh Chatter, Chief Executive Officer for Alsym Energy, commented, “ESS is a leading innovator in stationary storage, and we are very pleased to be partnering with them. As demand grows, it is increasingly clear that the industry needs solutions beyond lithium-ion to meet the speed and scale projections. By combining high performance, inherent safety, and supply chain resilience, Alsym’s Na-Series delivers that capability and ESS brings deep experience delivering grid-scale systems that maximize the value of renewable energy. Together, we are enabling a better path forward for energy storage.”

With the combined sodium-ion and iron-flow platform, ESS is positioned to support utilities, IPPs, data centers, and C&I customers seeking American-made, flexible, and future-proof energy storage solutions across a wide range of applications.

About ESS Tech, 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.

About Alsym Energy

Alsym Energy is enabling a safer, scalable energy future by rethinking battery chemistry. The company’s flagship Na-Series are non-flammable, high-performance, low cost sodium-ion batteries made with earth abundant materials. They are designed using a proprietary, physics-informed AI platform that enables the discovery of materials and commercially viable chemistries 10x faster than traditional, trial and error experiment-only methods. By combining DeepTech expertise in batteries with physics-informed AI, the platform is a closed-loop system that accelerates the entire battery development process, from ideation to manufacturing. Alysm’s Na-Series technology eliminates thermal runaway and allows energy storage to be deployed safely, and at scale, anywhere energy storage is needed — from data centers and industrial facilities to residential buildings, commercial real estate, mining, military installations or utility grids. Its wide operating temperature range avoids the need for HVAC systems for safety or performance, and fast charge and discharge rates allow multiple cycles per day, creating a powerful economic model for energy storage systems. Alsym Na-Series: A better battery for energy storage. To learn more, visit www.alysm.com.

Forward-Looking Statements

This communication contains certain forward-looking statements, including statements regarding ESS and its management team’s expectations, hopes, beliefs, intentions or strategies regarding the future. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intends,” “may,” “might,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “will,” “would” and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. Examples of forward-looking statements include, among others, statements regarding the Company’s productization, manufacturing and delivery of the Energy Base and relationships with customers, including Salt River Project. These forward-looking statements are based on ESS’ current expectations and beliefs concerning future developments and their potential effects on ESS. 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, 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 Quarterly Report on Form 10-Q filed on November 13, 2025, 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.

Contacts

Investor Relations
Chris Tyson
Executive Vice President
MZ Group – MZ North America
Phone: (949) 491-8235
[email protected]
www.mzgroup.us

Media
Brad Dore
VP, Marketing
ESS Tech, Inc.
Phone: (916) 207-7355
[email protected]

Agreement Supports Advancement and Real-World Evaluation of ESS’s Non-Lithium Long Duration Energy Storage Energy Base Technology

Collaboration Expected to Support Utility and Large-Load Sustainability Objectives, and Clean Energy Goals of Project Participants

WILSONVILLE, Ore. – March 3, 2026 – ESS Tech, Inc. (NYSE: GWH) (ESS, or the Company), a leading manufacturer of long-duration energy storage (LDES) systems for commercial and utility-scale today applications, today announced a collaboration framework with Salt River Project (SRP) and Google for Project New Horizon to advance long-duration energy storage innovation at SRP’s Copper Crossing Energy and Research Center in Florence, Arizona.

Project New Horizon is a five-megawatt (MW), 50 megawatt hour (MWh) system that will deploy ESS’ iron flow Energy Base technology and represents a significant commercial validation milestone for the Company’s next-generation, utility-scale platform. The pilot is expected to support SRP’s evaluation of emerging non-lithium LDES technologies and, if successfully executed, could help unlock follow-on commercial opportunities with utilities and large energy users seeking scalable, LDES solutions.

ESS’s Energy Base is designed for utility-scale deployments and differs from prior containerized solutions by enabling flexible configuration across diverse use cases and is expected to deliver cost advantages at larger scale.

The Project New Horizon pilot was awarded through SRP’s competitive solicitation process for LDES technologies. Design is underway, with manufacturing expected to begin in 2026 and delivery targeted for December 2027.

Under the agreement, SRP intends to partner with Electric Power Research Institute (EPRI) to support project operational testing under an initial, multi-year research scope, with potential for future work. All tests required per the Energy Storage Agreement (ESA) will be performed by SRP and ESS for the duration of the agreement term, with EPRI providing independent oversight.

Google is a participant in the Copper Crossing project, funding a portion of the project’s payments through a cost sharing arrangement with SRP. The collaboration is intended to evaluate real-world operational performance of non-lithium LDES and generate learnings relevant to grid reliability, renewable integration, and broader LDES deployment pathways. SRP and Google have both stated goals to expand clean energy and help make reliable, affordable electricity available around the clock.

“This phase of Project New Horizon represents an important commercial validation of Energy Base and a clear signal that utilities are actively pursuing scalable, non-lithium long-duration storage as part of long-term resource planning,” said Drew Buckley, Chief Executive Officer of ESS. “The collaboration with SRP, along with Google’s participation and cost sharing, reinforces the relevance of long-duration storage for grid reliability and for large energy users focused on carbon-free energy. Successful execution can serve as a blueprint for broader deployments and meaningful follow-on opportunities.”

“Project New Horizon is part of SRP’s effort to evaluate the impact of long-duration energy storage technologies that could ultimately support SRP’s mission of providing reliable, affordable and sustainable power,” said Chico Hunter, Manager, Innovation and Development at SRP. “We look forward to working with ESS, Google, and EPRI to assess performance in real-world conditions and advance our understanding of how long-duration storage can serve future system needs.”

“Long-duration energy storage is needed to improve grid resilience and unlock around-the-clock clean energy,” said Lucia Tian, Head of Advanced Energy Technologies, at Google. “This collaboration with SRP is intended to accelerate learning and innovation from real-world deployments of a portfolio of emerging long-duration energy storage technologies, including this first pilot with ESS. We’re excited to work with a utility partner who shares our commitment to supporting a range of technologies and diverse supply chains that can bring reliable, affordable, and clean energy to Arizona and across the United States.”

About ESS Tech, 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.

Forward-Looking Statements

This communication contains certain forward-looking statements, including statements regarding ESS and its management team’s expectations, hopes, beliefs, intentions or strategies regarding the future. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intends,” “may,” “might,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “will,” “would” and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. Examples of forward-looking statements include, among others, statements regarding the Company’s productization, manufacturing and delivery of the Energy Base and relationships with customers, including Salt River Project. These forward-looking statements are based on ESS’ current expectations and beliefs concerning future developments and their potential effects on ESS. 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, 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 Quarterly Report on Form 10-Q filed on November 13, 2025, 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.

Contacts

Investor Relations
Chris Tyson
Executive Vice President
MZ Group – MZ North America
Phone: (949) 491-8235
[email protected]
www.mzgroup.us

Media
Brad Dore
VP, Marketing
ESS Tech, Inc.
Phone: (916) 207-7355
[email protected]

Veteran Energy Storage Commercial Leader to Drive Global Commercial Execution as ESS Strengthens Leadership Team and Scales Deployments

Wilsonville, OR – February 19, 2026 – ESS Tech, Inc. (NYSE: GWH) (“ESS” or the “Company”), a leading innovator in long-duration energy storage solutions, today announced that Randall “Randy” Selesky has joined the company as Chief Commercial Officer (CCO). In this role, Selesky will lead global commercial strategy, sales, marketing, product management, and business development initiatives as ESS advances commercialization and scales deployment of its long-duration energy storage solutions worldwide.

Selesky joins ESS with more than 20 years of leadership in the energy sector, including more than a decade in the battery storage industry. Prior to joining ESS, he served as the Chief Commercial Officer at VoltStorage, where he played a central role in shaping commercial strategy, building partnerships, and guiding the company’s market expansion. Throughout his career, Selesky has been recognized for his ability to transform commercial organizations, build high-performing teams, and accelerate the adoption of innovative clean-energy technologies. His background encompasses large-scale market development, enterprise-level sales, and driving revenue growth in rapidly evolving segments of the energy transition.

This appointment builds on ESS’s recent leadership transformation designed to strengthen governance, execution, and financial discipline, with an emphasis on capital allocation and accountability. At ESS, Selesky will spearhead commercial execution as global demand for long-duration energy storage (LDES) continues to rise. His expertise positions the company to expand its market presence and meet the growing need for long-duration assets capable of improving grid reliability, enabling deeper renewable integration, and supporting the shift toward a decarbonized energy system.

“Randy is a proven commercial leader with extensive experience in the energy and battery storage industries, building high-performing teams, and converting market demand into durable revenue,” said CEO Drew Buckley. “His leadership will be instrumental as we sharpen execution and deliver high-performing, market-ready solutions to customers seeking reliable long-duration storage.”

Mr. Selesky added, “I am excited to join ESS at an important moment for the Company and for the broader energy industry. Long-duration storage is becoming essential for the next phase of the energy transition, and ESS is uniquely positioned with a safe, sustainable solution and a strong foundation to accelerate commercial momentum ready to meet the market’s needs. I look forward to helping scale customer adoption globally.”

About ESS Tech, Inc.

ESS (NYSE: GWH) is the leading provider of non-lithium 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 materials, ESS solutions enable 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.

Forward-Looking Statements

This communication contains certain forward-looking statements, including statements regarding ESS and its management team’s expectations, hopes, beliefs, intentions or strategies regarding the future. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intends,” “may,” “might,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “will,” “would” and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. Examples of forward-looking statements include, among others, statements regarding the Company’s 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. These forward-looking statements are based on ESS’ current expectations and beliefs concerning future developments and their potential effects on ESS. 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, 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 Quarterly Report on Form 10-Q filed on November 13, 2025, 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.

Contact

Investor Relations
Chris Tyson
Executive Vice President
MZ Group – MZ North America
Phone: (949) 491-8235
[email protected]
www.mzgroup.us

Media
Brad Dore
VP, Marketing
ESS Tech, Inc.
Phone: (916) 207-7355
[email protected]

Acquisition Expands ESS Technology Portfolio and Strengthens Path to Lower-Cost, Scalable Long-Duration Storage

Key VoltStorage Executive and Engineering Personnel Join ESS, Strengthening the Commercial and Technical Bench

Wilsonville, OR – February 18, 2026 – ESS Tech, Inc., (“ESS” or the “Company”) a leading innovator in long-duration energy storage solutions, today announced the acquisition of the intellectual property and assets of VoltStorage GmbH, a pioneer in iron-salt battery technology. This strategic move combines two complementary technologies to deliver the most flexible, cost-effective long-duration energy storage solution available on the market. The combined platform will set a new industry standard for performance, sustainability, and affordability. This acquisition adds VoltStorage’s portfolio of patents and technical development work to ESS’ robust existing intellectual property base. Through the transaction, ESS also gains access to skilled personnel with deep electrochemistry, materials science, and technology development background.

ESS believes the combined capabilities will accelerate strategic growth, expand market reach, and position the company at the forefront of long-duration energy storage solutions.

The resulting solution will enable utilities, renewable developers, and industrial customers to discharge energy over extended durations to improve grid reliability and increase the usable value of intermittent renewable generation, delivering the industry’s lowest Levelized Cost of Energy (LCOE).

Key Benefits of the Combined Technology:

• Flexibility: Potential to address a wider range of diverse applications, from grid-scale storage to industrial microgrids.
• Lowest Cost Long-Duration Storage: Leveraging abundant, sustainable materials to deliver superior economics.
• Sustainability and Scale: Iron-based chemistry ensures environmental responsibility and operational safety.
• Enhanced U.S. Manufacturing Platform: Deploys international development expertise at ESS’ American manufacturing facility

“This acquisition accelerates our mission to provide clean, reliable, and affordable energy storage solutions worldwide,” said Drew Buckley, CEO of ESS. “By combining decades of iron flow battery expertise across two companies at ESS, we are accelerating innovation to create the most advanced iron-salt battery platform for long-duration storage.”

About ESS Tech, 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.

Forward-Looking Statements

This communication contains certain forward-looking statements, including statements regarding ESS and its management team’s expectations, hopes, beliefs, intentions or strategies regarding the future. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intends,” “may,” “might,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “will,” “would” and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. Examples of forward-looking statements include, among others, statements regarding the expected integration of the VoltStorage intellectual property and technology, ESS product development and manufacturing, and relationships with customers. These forward-looking statements are based on ESS’ current expectations and beliefs concerning future developments and their potential effects on ESS. 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, 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 Quarterly Report on Form 10-Q filed on November 13, 2025, 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.

Company
[email protected]

Investor Relations
Chris Tyson
Executive Vice President
MZ Group – MZ North America
Phone: (949) 491-8235
[email protected]
www.mzgroup.us

Media
Brad Dore
VP, Marketing
ESS Tech, Inc.
Phone: (916) 207-7355
[email protected]