Sunrun and Tesla Push 580 MW From 140,000 Home Batteries Into California’s Evening Peak
- Energy Storage Grid Services & Demand Response News
Marin Holt
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- 7 minutes read
- Peak Dispatched: 580 MW
- Home Batteries: 140,000
- From Tesla Powerwalls: 517 megawatts
- Dispatch Window: Three hours, evening of September 9, 2026
- Projected Net Savings: $206 million by 2028
Sunrun and Tesla dispatched more than 580 megawatts from more than 140,000 home batteries to California’s grid on the evening of September 9, 2026. The California Energy Commission and utilities asked for the power during a heat wave. Sunrun calls it the largest residential distributed power plant event on record.
Tesla Powerwalls supplied 517 megawatts of that total. About 110,000 Powerwalls took part, and Sunrun owns or operates 55 percent of them. Another 30,000 batteries from other manufacturers in Sunrun’s fleet added 63 megawatts. The dispatch ran for a three-hour evening period.
Two Programs Triggered the Dispatch
Two separate California programs moved the batteries. The Demand Side Grid Support program, run by the California Energy Commission, fires once the CAISO day-ahead locational marginal price passes $200 per megawatt-hour. It did on September 9. The Emergency Load Reduction Program, run by the California Public Utilities Commission, lets utilities call enrolled batteries directly.
The September 9 event left out batteries enrolled in ELRP inside Southern California Edison territory. SCE asked for its own three-hour dispatch the next evening. Sunrun and Tesla delivered more than 140 megawatts on September 10.
Why It Matters
Residential batteries now answer the evening ramp, the hours when California leans hardest on gas peakers. The state gets that capacity without siting or permitting a plant. The exposure sits in the funding. Our April coverage found the state budget threatens the Demand Side Grid Support program in 2027, the same program that triggered this dispatch. A record set under one program says little about the year after that program’s money stops.
The Record It Beat
Last summer’s comparable event moved 535 megawatts across all three California utilities. Renewable Energy World notes the two dispatches did not overlap. Run at the same time, they would have pushed the combined figure past 720 megawatts.
The number also sits against slower aggregation work elsewhere in the state. PG&E enrolled 21,000 home devices in a Google-funded virtual power plant that targets 12 megawatts by 2028, as mgrid reported on September 4. Utility-scale batteries remain the larger fleet. California’s grid batteries passed 21,112 megawatts in August, by our earlier count.
Sunrun CEO Mary Powell said the batteries operate “at a scale larger than many peaker power plants combined.” A Brattle Group report commissioned by Sunrun and Tesla projects up to $206 million in net savings for Californians by 2028.
Critical Perspective
Three things sit behind the record. First, 580 megawatts beats last summer’s 535 megawatts. It is worth asking how much of that gain is fleet growth rather than better performance. Second, the 720 megawatt figure never happened. The September 9 and September 10 dispatches ran on different nights, so that total is arithmetic the companies published, not power delivered. Third, the Brattle Group report behind the $206 million estimate was commissioned by Sunrun and Tesla, the two firms whose programs it evaluates. The harder question is what moves the fleet. DSGS fires on a day-ahead price above $200 per megawatt-hour. That is a market signal, not a reliability call, and the state budget has already put the program’s 2027 funding in question.
Sources
- Sunrun, “Sunrun and Tesla Dispatch 580 Megawatts To California’s Grid During Heat Wave,” September 21, 2026
- Electrek, “Tesla and Sunrun’s virtual power plant dispatch record 580 MW to California grid,” September 21, 2026
- Renewable Energy World, “Look what DERs can do: 580 MW sent to the grid in largest-ever VPP dispatch,” September 21, 2026
