Iron flow battery company ESS Tech Inc highlighted the potential of its recent partnership with Google and the acquisition of VoltStorage GmbH, as profitability remained out of reach in 2025.
The Oregon, US-based technology firm, which owns the intellectual property for a proprietary flow battery using iron and saltwater electrolyte for long-duration energy storage (LDES) applications, announced its Q4 2025 and full-year 2025 financial results on 5 March.
ESS Inc reported a fiscal year (FY) 2025 net loss of US$63.4 million, a US$22.8 million improvement from FY 2024’s loss of US$86.2 million.
The company reported FY 2025 revenue of US$1.6 million, a 75% change from US$6.3 million in FY 2024.
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It reported FY 2025 operating expenses of US$29.7 million, down from US$44.4 million in FY 2024, a 33% decline.
Adjusted EBITDA was US$-44.3 million, compared to US$-71.3 million in FY 2024. This represents a 38% change.
The company highlighted that gross profit increased by 36%, operating expenses dropped by 33%, and the net loss was reduced by US$23 million. It stated that ongoing reductions in the cost of revenue and operating expenses reflect the company’s cost-cutting efforts, along with a significant decrease in the operating cash burn rate.
ESS Inc’s shares were listed on the New York Stock Exchange (NYSE) in 2021, amid a surge of energy storage tech startups going public through special purpose acquisition company (SPAC) mergers between 2020 and around 2023.
The company has struggled to reach its previous all-time high share price of US$281.25 in 2021. Its leadership did warn that profitability would likely take some time.
In 2025, when reporting its Q1 financials, ESS Inc said it would be pivoting to its Energy Base product and discontinuing its two existing, smaller configurations, Energy Warehouse and Energy Center. Energy Base is designed to deliver 12- to 14-hour long-duration storage solutions for customers like data centres and large renewable energy operators.
Earlier this month, the company announced it would be collaborating with Arizona utility Salt River Project (SRP) and tech giant Google for Project New Horizon, a 5MW/50MWh system using ESS’ iron flow Energy Base technology.
Project New Horizon was selected via SRP’s competitive process for LDES technologies. Design is in progress, with manufacturing planned for 2026 and delivery aimed for December 2027.
The company also recently acquired the intellectual property and assets of VoltStorage GmbH, an iron-salt battery developer. This move enhances ESS’ portfolio by including VoltStorage’s patents and technical development resources based in Germany. ESS also benefits from the expertise of VoltStorage GmbH staff in electrochemistry, materials science, and technology development.
ESS highlights these recent developments, as well as the appointment of its new CEO, Drew Buckley, following the resignation of former CEO Kelly Goodman in February of last year, as opportunities for growth over the next year.
The Energy Storage Summit USA 2026 will be held from 24-25 March 2026, in Dallas, TX. It features keynote speeches and panel discussions on topics like FEOC challenges, power demand forecasting, and managing the BESS supply chain. ESN Premium subscribers can get an exclusive discount on ticket prices. For complete information, visit the Energy Storage Summit USA website.
