California Home Batteries Deliver Record 745 MW During October Heat Wave

During California’s October heat wave, residential battery systems collectively discharged 745 megawatts into the state’s power grid — a figure that surpasses most of the state’s gas peaker plants and, according to Sunrun, roughly matches peak-hour electricity consumption across San Francisco and San Jose combined.

The record was set on October 6, when more than 85,000 Tesla Powerwall owners contributed over 600 MW, accounting for approximately 80 percent of the total discharge. Average output per participating household reached 7 kW — a level that likely reflects the growing share of Powerwall 3 units and homes running multiple battery packs. The result represented a 28 percent increase over the previous record of 580 MW, set in September.

Battery owners receive direct payments for grid support through two California programs: the Demand Side Grid Support program (DSGS) and the Emergency Load Reduction Program (ELRP). Sunrun CEO Mary Powell noted that these payments give customers a concrete financial return for contributing to grid stability. DSGS activates when day-ahead electricity prices exceed $200 per megawatt-hour — a threshold crossed repeatedly during the October peaks.

The payment structure is central to how the model functions at scale. Without programs of this kind, coordinated residential discharge would not currently operate at such volumes. Comparable demand-response mechanisms for home batteries are absent in most other U.S. states, which constrains how broadly the approach could be applied today.

Source: Electrek