On the evening of September 9, a coordinated fleet of residential battery systems across California simultaneously discharged 580 megawatts into the state grid \u2014 more than double the upper end of what a single gas peaking plant typically produces (50\u2013250 MW). The event is the largest on record for a distributed residential virtual power plant, according to Electrek.<\/p>\n
Sunrun and Tesla synchronized more than 140,000 home battery installations statewide. Tesla Powerwalls accounted for the bulk of the output at 517 MW; units from other manufacturers contributed the remaining 63 MW. Over the three-hour dispatch window, the combined capacity was sufficient to supply every household in Sacramento County.<\/p>\n
Two existing California grid support programs drove the response. The DSGS program activated automatically once electricity prices exceeded $200 per megawatt-hour, while utilities separately triggered the ELRP program as air-conditioning demand peaked. Participating homeowners received financial compensation for the energy their batteries fed back to the grid.<\/p>\n
The Electrek author argues that mobilizing equipment households already own could serve as a practical alternative to maintaining costly gas peakers that sit idle for much of the year. Whether the model can scale far enough to genuinely threaten the economics of those plants \u2014 or of grid-scale industrial storage \u2014 remains an open question. Wider adoption also depends on the availability of supporting programs and price signals, conditions that most U.S. states have yet to establish.<\/p>\n