MN8 Energy brings 400 MWh tolled standalone battery online in Southern California

Independent solar and battery storage producer MN8 Energy has brought its 100 MW / 400 MWh Pome battery energy storage system (BESS) into commercial operation in Poway, California, adding additional capacity to the California Independent System Operator (CAISO) grid. This takes MN8 Energy’s operational storage portfolio in California to 1.5 GWh.

The stand-alone battery, completed in late 2025, is contracted to Sonoma Clean Power (SCP) under a 10-year tolling agreement.

The project has been a typical battery moving between companies. It was originated by Eolus North America which began greenfield development on the standalone project. Eolus took the Final Investment Decision (FID) in 2023 and started construction in the same year, while also signing the PPA. It then announced the sale of the project in Jnuary 2025 to an unnamed energy producer, with the transaction closing on February 25, 2025. By late 2025, construction was complete and operations underway. Finally, this week, MN8 stepped up to claim ownership and operations.

Located on nearly 4 acres in an industrial site in San Diego County, MN8 gave out information to boost its community profile. It said in its announcement that it predicts the Pome project will deliver $20 million in local government revenue, and around $28 million in new property tax contributions over its first seven to 10 years of operation. The company said this will support school funding and essential public services.

MN8 Energy president and CEO, Jon Yoder, said “MN8 is proud to bring the Pome storage project online to serve Sonoma Clean Power and its customers, providing fast‑responding capacity that can support California’s grid within seconds.”

Geof Syphers, CEO of SCP added: “Battery storage like Pome is how we turn California’s abundance of renewable energy into reliable, affordable power. This project strengthens the grid and moves us closer to the 24/7 clean energy future we’ve been building toward since day one.”

In addition to the 1.5 GWh of battery energy storage capacity, MN8 Energy has approximately 4 GW of operational and under-construction solar projects. Last year, MN8 Energy secured $575 million of senior secured notes with Natixis Corporate & Investment Banking.