10% of California's EVs Could Provide 9 GW Grid Support

California is exploring the transformation of millions of parked electric vehicles (EVs) into distributed 'mobile power plants.' A new report jointly released by GridLab, Kevala, and Energy & Environmental Economics finds that if just 10% of the state's projected EV fleet participates in vehicle-to-grid (V2G) programs by 2036, it could deliver approximately 9 gigawatts (GW) of grid regulation capacity for 12 hours — equivalent to 108 gigawatt-hours (GWh) of flexible energy storage, exceeding one-third of California's annual long-duration storage target.

V2G technology enables compatible vehicles to feed electricity from their onboard batteries back into the grid during periods of high demand; owners can then recharge when electricity prices are low and renewable generation is abundant — such as during midday solar peaks. This bidirectional interaction not only enhances grid resilience but also creates potential revenue streams for users.

The report, titled Unlocking California's Flexible Load: A Sustainable Roadmap for Affordability and Reliability, emphasizes that beyond EVs, residential battery storage, smart thermostats, electric water heaters, and commercial building loads can all serve as aggregated 'virtual power plant' (VPP) resources — reducing reliance on new fossil-fueled generation, large-scale battery installations, and costly grid upgrades.

Although hardware capabilities are maturing rapidly, real-world barriers lie in institutional design: today, California's investor-owned utilities — including PG&E, SCE, and SDG&E — operate demand response programs with inconsistent eligibility rules, compensation mechanisms, and technical requirements. 'The next-generation grid infrastructure is already parked in our driveways, sitting in our homes, and installed in our office buildings,' said Ric O'Connell, Executive Director of GridLab. 'The question isn't whether the resources exist — it's whether current programs can truly unlock their full value.'

The report calls for a statewide standardized program framework — including uniform technical interface specifications, performance-based compensation (verified against actual grid benefits rather than simple enrollment), and compensation caps set below each utility's avoided cost — to ensure rate fairness for customers without EVs or storage. This 'affordability guardrail' directly addresses the core controversy surrounding California's rooftop solar incentives: preventing system costs from being shifted onto non-participating ratepayers.

This roadmap builds upon conclusions from a 2024 joint study by GridLab and The Brattle Group, which found that commercially available VPP technologies could meet over 15% of California's peak electricity demand — and save utilities and consumers $550 million annually. Notably, these figures represent modeled potential, not yet realized operational benefits. Full-scale V2G deployment still hinges on multiple co-dependent conditions: vehicle compatibility, widespread adoption of bidirectional chargers, unified interconnection policies, and sustained user participation.

Even without bidirectional capability, unidirectional smart charging delivers significant value: automated load shifting can prevent millions of EVs from simultaneously charging during evening peak hours — effectively relieving grid stress. The California Energy Commission notes that automated flexible load management both defers expensive infrastructure investments and improves local renewable energy utilization rates.

What California faces is not a battery shortage — but an urgent need to build a truly integrated, statewide flexible resource orchestration system spanning 'vehicle–charger–grid–user.'