Sunrun (NASDAQ: RUN) and Tesla (NASDAQ: TSLA) said their combined fleets of home batteries dispatched more than 580 megawatts of peak power to California's electrical grid on the evening of September 9, 2026, during a period of extreme heat and elevated electricity demand.

The event involved more than 140,000 home batteries and was carried out over a three-hour evening period at the request of the California Energy Commission and state utilities. The dispatch was coordinated through two statewide programs: the California Energy Commission's Demand Side Grid Support program and the California Public Utilities Commission's Emergency Load Reduction Program.

Of the 580 megawatts dispatched, 517 megawatts came from Tesla Powerwalls, with 110,000 units participating. Sunrun operates more than half of those Powerwalls. Sunrun also dispatched more than 30,000 batteries from other manufacturers, contributing 63 megawatts.

The Demand Side Grid Support dispatch was triggered when California's day-ahead locational marginal price exceeded $200 per megawatt-hour. Pacific Gas and Electric called the Emergency Load Reduction Program dispatch to coincide with the heat event.

On September 10, Southern California Edison requested a separate three-hour dispatch, during which Sunrun and Tesla delivered more than 140 megawatts. The companies said a combined dispatch across both nights would have totaled over 720 megawatts.

"Sunrun's distributed home batteries are operating at a scale larger than many peaker power plants combined," said Sunrun CEO Mary Powell.

A report by The Brattle Group, commissioned by Sunrun and Tesla, estimated that such programs could provide up to $206 million in net cost savings to Californians by 2028.

Sunrun, Tesla, and Renew Home have a separate initiative aimed at enrolling nearly 21,000 existing flexible energy devices into a Google-funded distributed power plant with PG&E, which is expected to begin supporting the grid as early as this fall.