Parked electric vehicles in California could become one of the state’s largest sources of energy storage, according to estimates in a new report prepared by GridLab, Kevala, and Energy and Environmental Economics. The report concludes that enrolling just 10% of the electric vehicles expected in the state in vehicle-to-grid (V2G) programs by 2036 could provide approximately 9 gigawatts of capacity for 12 hours.
This potential is equivalent to 108 gigawatt-hours of storage, or more than one-third of California’s long-duration storage target for that year. These are modeled figures reflecting expected potential, not savings or capacity currently achieved by the state.
How Do Vehicles Serve as a Grid Resource?
V2G technology enables a compatible electric vehicle to send some of the energy stored in its battery to the grid when electricity demand rises. The vehicle can be recharged during periods when electricity is cheaper and more available, such as midday hours with high solar energy production.
The concept is not limited to sending energy back to the grid. Smart, one-way charging can also ease pressure by scheduling the charging of millions of vehicles outside the evening peak-demand period or shifting consumption to lower-cost hours that are more aligned with renewable energy production.
What Is Hindering Expansion?
The report, titled “Unlocking California’s Flexible Load: A Durable Blueprint for Affordability and Reliability,” finds that the core problem is not a lack of batteries or devices capable of providing flexibility to the grid, but rather the fragmented participation rules among utilities. Registration requirements, financial structures, and technical conditions vary from one program to another.
Other resources that can be used to manage demand include home batteries, smart thermostats, water heaters, and commercial buildings. Ric O’Connell, GridLab’s executive director, said the next generation of grid infrastructure already exists in vehicles, homes, and businesses, but program design determines whether it can be fully utilized.
What Is Changing in Practice?
The report calls for adopting standardized program designs throughout California, establishing common technical requirements, and tying payments to verifiable actual performance. Rather than rewarding customers simply for enrolling, participants would receive compensation proportionate to the value their vehicles or batteries provide to the grid.
The report also proposes that payments be lower than the costs avoided by the utility, leaving part of the savings available to customers who do not own an electric vehicle, battery, or flexible device. This restriction is intended to limit the possibility of shifting grid costs to other subscribers, a concern that is present in discussions about residential solar incentives in California.
The Potential Depends on Participation
The new report builds on a 2024 study prepared by GridLab and The Brattle Group, which estimated that virtual power plants based on commercially available technologies could meet more than 15% of California’s peak electricity demand while saving utilities and customers $550 million annually.
However, realizing this potential requires vehicles to be plugged in and available when needed, along with vehicle and charger compatibility, utility program availability, and clear grid interconnection rules. Therefore, California’s challenge is less about finding more batteries than about building a standardized system capable of actually using them.