Shares of Eos Energy Enterprises surged 12% on Wednesday after the company unveiled plans for a $350 million integrated solar and energy storage project in West Virginia.
The Mammoth Solar project, located on a reclaimed coal mine in Kanawha County, combines 86 MW of utility-scale solar capacity with two storage systems: a 10 MW/100 MWh zinc-based long-duration storage unit from Eos and a 70 MW/280 MWh lithium-ion system. The project will supply clean, dispatchable power to the PJM grid, primarily serving Google’s data centers in the region, including a planned facility in West Virginia.
The 10 MW/100 MWh zinc-based system, using Eos’s Z3 technology, represents the first deployment of U.S.-manufactured long-duration storage by the company. It is scheduled for completion in 2030, with the lithium-ion storage system slated for 2029 and the solar component expected to begin commercial operations in 2028. MN8 Energy will own and operate the project, while Google will acquire the energy, capacity, and clean energy attributes.
The project is expected to generate roughly $4 million in property tax revenue for the county and local schools over its first 20 years and create about 200 jobs during construction. The integrated portfolio is designed to provide 10 hours of storage from the zinc-based system, enhancing grid reliability for the region’s data center infrastructure.
