Eos Energy Enterprises has installed a new production line for its zinc-powered aqueous liquid battery platform, with a view to reaching 4 GWh annual production capacity at the company’s US factory by the end of 2026.
Commercial production has begun on the second battery line at its the US manufacturer’s Thorn Hill facility in Marshall Township, Pennsylvania, following the successful completion of site acceptance testing.
Commissioning a second battery line comes as Eos attempts to significantly ramp up production ahead of some major supply obligations. The manufacturer claims it has already improved production speed on its first line, surpassing its full year 2025 output in the first 164 days of 2026.
Eos manufactures a zinc-based flow battery module that’s targeted at long-duration energy storage (LDES) applications. The Eos Z3 battery contains three proprietary components – non-degradable bipolar electrodes, a high-performance aqueous electrolyte, and fully-sealed polymer casing – and the manufacturer reportedly has more than 200 patents pending, published or issued that are associated with the design.
Like other flow battery designs, Eos Energy’s Z3 battery module contains an electrolyte that enables ion transport between the electrodes. During charging and discharging, ions move through the electrolyte between the electrodes. The Z3 battery stores electrical energy through zinc deposition on its electrodes. Eos claims the battery module can have an operational life of at least 25 years and it is targeted at four- to 16-hour discharge applications.
Eos Energy’s second manufacturing line has been commissioned as the company prepares to supply major LDES projects in Texas and the United Kingdom.
Eos has a supply agreement with Frontier Power USA (FPUSA), which already has 2 GWh capacity reservation agreements in place. FPUSA announced in May 2026 that it had acquire a 480 MWh battery project portfolio in Texas from Bimergen Energy, and this was followed by a strategic framework agreement with Stella Energy Solutions to advance a 2 GWh pipeline built around Eos technology.
The UK market has also opened up to Eos Energy Enterprises, and the manufacturer expects to supply projects currently in the running for contracts under the government backed cap-and-floor support scheme.
Frontier Power UK has acquired two long-duration energy storage projects under development in Scotland. The projects are expected to use approximately 2.8 GWh of Eos Z3 Idensity battery storage systems under an existing agreement announced between the manufacturer and developer in April 2025. A decision on whether the Ayr and Busby LDES projects will secure cap-and-floor support from the UK government is expected in summer 2026.
John Mahaz, chief operating officer at Eos, said that the company’s second battery line demonstrates an ability to continuously improve while scaling.
“We took the lessons learned from commissioning and operating Line 1 and incorporated them directly into the design of this facility and production line. The result is a more efficient manufacturing environment with better flow and a stronger foundation for future expansion. Most importantly, it validates that our manufacturing system can be replicated and scaled with discipline,” Mahaz said.
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