MN8 Energy Brings 100 MW / 400 MWh Pome Battery Online

MN8 Energy LLC announced on May 19, 2026 the commercial operation of Pome, a 100 MW / 400 MWh standalone battery energy storage system (BESS) in Poway, California, fully contracted to Sonoma Clean Power (SCP) under a 10-year tolling agreement. SCP will use the four-hour-duration facility to store, manage, and dispatch energy into the California Independent System Operator (CAISO) market in support of its 24/7 clean-energy commitment, MN8 said. S1

What was built

Pome is a 100 MW / 400 MWh standalone battery — a four-hour system at rated power — sited on 3.98 acres in an industrial area of San Diego County. As a standalone (non-colocated) asset, it charges from the grid and discharges on dispatch rather than pairing with a specific generator, giving its offtaker flexibility to arbitrage energy and provide capacity. With Pome online, MN8’s operational storage portfolio in California reaches 1.5 GWh of grid-scale capacity serving CAISO. S1

The contract structure

The 10-year tolling agreement is the financial spine of the deal. Under a toll, Sonoma Clean Power pays MN8 a fixed capacity-style fee for the right to charge and dispatch the battery, while SCP captures the energy-market value and bears price risk. That structure gives MN8 contracted, bankable revenue independent of daily CAISO spreads and gives SCP — a community-choice aggregator — direct control of a fast-responding resource. MN8 President and CEO Jon Yoder said Pome provides “fast-responding capacity that can support California’s grid within seconds.” S1

Critical Perspective

The economics rest on the four-hour duration. A 400 MWh battery can cover the evening net-load ramp that drives CAISO prices, but as the state’s storage fleet crosses 15 GW the value of a fifth four-hour resource discharging into the same window compresses — the “duration arbitrage” that made early CAISO batteries lucrative is being competed away. MN8’s release also dates commercial operation to “late 2025,” with the May 19, 2026 announcement following months later; the projected “$20 million in revenue for local governments and approximately $28 million in new property tax contributions” is a seven-to-ten-year estimate, not realized income. S1

Why It Matters

Pome shows the contracting model that is financing California’s storage buildout: a community-choice aggregator signing a long-term toll with an independent power producer to lock in fast capacity, rather than building or merchant-operating the asset itself. For Sonoma Clean Power, it is a concrete step toward round-the-clock clean supply; for the CAISO market, it adds 100 MW of sub-second flexibility exactly where the grid needs it during the solar-to-evening transition. As the fleet scales, the projects that pencil out will increasingly be the contracted, tolled ones — Pome is a representative example. S1

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