ESS Tech Inc
essinc.comESS Tech Inc (NYSE: GWH) is an energy storage company that designs and manufactures long-duration iron flow batteries for commercial and utility-scale applications. Revenue is generated through the sale of energy storage products to customers under contracts, with the company still in the early stage of commercialization as of the 10-K filed 2026-03-05. ESS Tech was founded in 2011 by Craig Evans and Dr. Julia Song, who built on iron flow battery research originating in the 1970s. The company's core proprietary technology is the Proton Pump, a patented mechanism that eliminates hydroxide formation in the electrolyte, enabling a 20,000-cycle design life without capacity fade. Partnerships include a framework agreement signed in April 2021 with SBE, an affiliate of SoftBank Group Corp., to supply energy storage products, as well as a joint development relationship with Honeywell. The company's batteries are made predominantly from earth-abundant materials, avoiding rare earth metals. ESS Tech is early-stage, faces significant commercialization barriers, and has experienced leadership transitions that the 2026-03-05 filing identifies as an operational risk.
Products & Services
Long-duration iron flow batteries incorporating the proprietary Proton Pump technology, designed for commercial and utility-scale energy storage. The batteries use iron-based, earth-abundant materials. The company also offers project surety through a partnership with OneBeacon Insurance.
Revenue Model
Product sales of iron flow battery energy storage systems to commercial and utility-scale customers under contracts. The company is in early commercialization and the filing does not disclose segment revenue breakdowns or specific revenue figures in the provided excerpts.
Customers & Markets
Commercial and utility-scale energy storage customers. SBE (SoftBank Energy affiliate) and Honeywell are named partners and potential customers. End markets include grid-scale and stand-alone battery storage, with relevance to the Investment Tax Credit regime expanded under the Inflation Reduction Act of 2022 to include stand-alone battery storage projects.
Geographic Exposure
The filing does not specify geographic revenue mix. The company references U.S. legislative developments, including the Inflation Reduction Act signed August 16, 2022, suggesting primary U.S. market focus, but geographic breakdown is not disclosed in the provided excerpts.
Source: SEC 10-K, filed 2026-03-05
Financial Snapshot
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