More than 56,000 Sunrun customers’ solar-plus-battery systems - totaling approximately 75,000 batteries -will provide critical energy to California's grid during times of high energy prices, heat waves, and other grid emergency events while simultaneously lowering energy costs for all ratepayers.
“Sunrun is leading the transformation of the energy grid with a customer-led revolution to a more reliable, energy independent way to power their homes while at the same time being a solution to help other Californians who rely solely on the grid” said Sunrun CEO Mary Powell. “The expansion of CalReady highlights our increasing role as a critical energy provider and underscores the system-wide value we’re delivering to ratepayers, utilities, and the grid.”
Sunrun’s CalReady power plant is the largest home storage aggregation in the California Energy Commission's Demand Side Grid Support programme. CalReady is available to support the state’s grid each day from 4 to 9 p.m. from May through October. This is the second year that Sunrun has operated CalReady as the nation’s largest virtual power plant.
In 2024, Sunrun’s CalReady power plant enrolled over 16,000 households and delivered an average of 48 megawatts of stored solar energy to the grid during summer heat waves, reaching an instantaneous peak of 54 megawatts. This year, CalReady’s power output has more than quadrupled and is expected to deliver an average of 250 megawatts per two-hour event, with the ability to reach an instantaneous peak of up to 375 megawatts - enough to power approximately 280,000 homes, equivalent to all of Ventura County, California.
“Sunrun has created one of the largest batteries in the country, rivaling large-scale utility projects but without taking up additional land or requiring costly new infrastructure” Ms Powell added. “CalReady’s decentralised nature eliminates any potential single point of failure while offering greater resilience and flexibility for the state’s evolving energy needs.”
Sunrun customers enrolled in CalReady are compensated up to $150 per battery for sharing their stored solar energy, and Sunrun is paid for dispatching the batteries. Last year, CalReady delivered more than $1.5 million in value to Sunrun customers and helped lower costs for all ratepayers, reduced pollution, and stabilized the grid for all electric customers in the state. This year, Sunrun customers are expected to collectively receive nearly $10 million for participating in the virtual power plant.
“Being rewarded for sharing energy with the grid from our two batteries makes CalReady a no-brainer” said San Jose resident and Sunrun customer Tom Weldon. “This will be our third year participating in Sunrun’s virtual power plants. We appreciate the relationships Sunrun develops with customers and utilities to create these programs that have mutual benefits. It’s a win all around.”
Sunrun’s direct compensation to customers is a stark contrast to the double-digit utility rate hikes in California, which are growing faster than inflation and significantly faster than the average electricity rates across the country.
The scale of CalReady is a direct result of Sunrun’s storage-first strategy. At the end of 2024, more than 60 percent of new Sunrun customers chose to add battery storage to their solar system. In California, the storage attachment rate was even higher at nearly 90 percent.
Sunrun actively monitors and dispatches participating batteries, making it a hassle-free experience for customers enrolled in CalReady. For customers with outage protection, batteries will still retain, at minimum, a backup reserve of 20 percent so that they can continue to power their homes in the event of a local power outage.
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