Google is backing a solar-plus-storage project developed by MN8 at a former West Virginia coal mine, featuring 100 MWh of long-duration Eos Energy Enterprises zinc-based storage alongside lithium-ion batteries.
Google will purchase the energy, capacity, and clean energy attributes of a solar-and-storage project planned on the site of a former coal mine in West Virginia, the tech giant and its partners announced on September 2, 2026. The Mammoth Solar project, located in Kanawha County and part of the PJM Interconnection system, will consist of 86 megawatts (MW) of utility-scale solar, 70 MW/280 megawatt-hours (MWh) of lithium-ion energy storage, and 10 MW/100 MWh of zinc-based long-duration energy storage developed by Eos Energy Enterprises. The solar component is expected to reach commercial operation in 2028, with the lithium-ion and zinc-based storage systems following in 2029 and 2030, respectively.
In a joint release, Google, developer MN8, and Eos stated that the project is designed to align clean energy capacity with Google’s regional data center load profiles throughout the day. The companies also noted that the project will deliver additional capacity across the PJM region, where recent auctions have seen capacity costs hit the price ceiling. To address a nearly 7 GW shortfall, a one-time backstop auction is scheduled for this fall.
The project marks one of the largest deployments of zinc-based batteries to date. According to the U.S. Department of Energy, most operational zinc battery installations have power ratings of 1 MW or less. Unlike conventional lithium-ion systems, Eos batteries utilize a nonflammable, zinc-based electrolyte and can economically discharge energy for longer than eight hours at a time. This summer, the Lincoln Electric System in Nebraska installed a 3 MW/12 MWh zinc battery to support a state government hub’s microgrid, highlighting the technology’s growing viability.
Last October, MN8 and Eos inked a supply agreement under which Eos could provide up to 750 MWh of its zinc-based Z3 battery modules to various MN8 projects within PJM and other U.S. markets. The companies indicated that the initial projects supported by this agreement would combine 200 MWh of 10-hour energy storage with solar generation. Separately, the Mammoth Solar project in West Virginia has no connection with Doral Renewables’ similarly named 1.3-gigawatt (GW) Mammoth Solar project in Indiana.
“This collaboration with MN8 and Eos aims to deploy a smart portfolio of round-the-clock technology solutions to help power our digital infrastructure,” said Lucia Tian, Google’s director of advanced energy technologies. Jon Yoder, president and CEO of MN8 Energy, credited Google for being “willing to pair next-generation storage with utility-scale solar” and allowing MN8 to design a customized solution for its facilities load profiles. The companies emphasized that the agreement is part of a broader effort to accelerate the commercialization of long-duration energy storage technologies.
In a separate development, Google is funding the construction of what Xcel Energy describes as one of the world’s largest battery installations of any kind: a 300 MW/30 GWh iron-air battery deployment in Minnesota. Manufacturer Form Energy states the system can provide up to 100 hours of full-power discharge. Like the West Virginia project, Google’s Minnesota installation is one component of a broader procurement of clean energy resources intended to support data centers the company plans to bring online in the region.