Overview
- MN8 Energy, Eos Energy Enterprises and Google announced the Mammoth Solar collaboration in a joint statement on Sept. 2–3 that frames the site as a packaged solar-plus-storage project for the PJM grid.
- The facility will pair 86 MW of utility-scale solar with two storage technologies: 70 MW/280 MWh of lithium-ion batteries and 10 MW/100 MWh of Eos’s Z3 zinc long‑duration system.
- The partners published a staged schedule that targets commercial operation of the solar array in 2028, the lithium-ion storage in 2029 and the Eos Z3 long‑duration storage in 2030.
- MN8 will own and operate Mammoth Solar on a reclaimed coal site in Kanawha County, West Virginia, with MN8 estimating up to $350 million in capital, about 200 construction jobs, and roughly $4 million in property tax revenue over the first 20 years.
- The announcement lifted Eos’s stock by about 12% on the day and nearly 19% after a recent 52‑week low, but the company still reports wider quarterly losses and narrowed 2026 revenue guidance while it consolidates U.S. manufacturing.