MN8 Energy, Google and Eos Energy Enterprises used a September 2 announcement to introduce Mammoth Solar, a first-of-its-kind clean energy portfolio in Kanawha County, West Virginia that couples utility-scale solar with two different storage chemistries to serve growing PJM demand from hyperscale data centers.
What The Project Actually Contains
MN8 will own and operate the site, which combines 86 MW of utility-scale solar, 70 MW / 280 MWh of lithium-ion energy storage and 10 MW / 100 MWh of Eos' Z3 zinc-based long-duration storage. The Z3 system is designed to deliver ten hours of discharge — extending the availability of solar generation beyond the shorter-duration lithium-ion tier and turning the whole portfolio into a dispatchable resource matched to a data center load profile. The solar block is scheduled to reach commercial operation in 2028, with lithium-ion storage following in 2029 and long-duration storage in 2030. It is the first commercial-scale long-duration energy storage deployment in West Virginia.
Google's First Z3 Buy
Under the deal, Google will purchase the energy, capacity and clean energy attributes of the entire project through a long-term agreement — its first project using Eos' American-made zinc chemistry. Lucia Tian, Google's Director of Advanced Energy Technologies, framed the transaction as backing solutions that both meet the company's data center capacity needs and accelerate progress toward cleaner, more affordable grids. It is also the first project delivered under the previously announced MN8–Eos master supply agreement.
Why West Virginia, And Why Now
The Mammoth Solar site sits on a reclaimed coal mine, layering a new energy-manufacturing story onto a community with an old one. MN8 estimates roughly $350 million in capital investment, about $4 million of local property tax revenue in the first 20 years, and around 200 construction jobs, with additional roles supporting operations. MN8 CEO Jon Yoder said the design reflects an approach the company has taken with other clients: pairing next-generation storage with utility-scale solar to engineer proven and emerging technologies into a single dispatchable resource.
The Long-Duration Storage Signal
The 10-hour Z3 system is meant to prove that Eos' aqueous zinc chemistry can support critical grid infrastructure at the same scale as lithium — a growing question as hyperscalers push clean-capacity procurement past the 4-hour window that lithium-ion is optimized for. It fits alongside other US moves this quarter, from Eos consolidating manufacturing at its Thorn Hill facility to Lincoln Electric System's 3 MW / 12 MWh Z3 microgrid and MN8's $375M Greenbacker acquisition that lifted its operating base above 4 GW. Eos CCO Nathan Kroeker said the collaboration focuses on deploying long-duration storage where it solves real reliability challenges rather than as a demonstration.
Reporting based on coverage from GlobeNewswire, pv-magazine USA, and Forbes.