Vehicle-to-grid: when a parked EV becomes a grid battery

The same hardware often does V2H first and V2G later. In Maryland, backup-only systems need just a utility notification, while grid export needs a full interconnection request (Microgrid Media). Managed charging is covered on our EV managed charging page.

DC or AC. Most bidirectional chargers are DC: the charger holds the inverter, as in the Wallbox Quasar 2 and dcbel Ara. Tesla’s Cybertruck uses AC export, with the inverter in the vehicle, which PG&E called the first AC vehicle-to-grid application approved in California (PG&E).

The vehicle-charger pair is the unit. PG&E and MassCEC both list approved pairs by model year. A capable vehicle outside the list earns nothing through those programs (PG&E, MassCEC).

Export limits are a ceiling, not a guarantee. What counts is the average kW delivered while the vehicle is plugged in during the event hours, which depends on driving schedules, the driver’s discharge floor and the charger. A vehicle that is away when an event is called delivers zero.

Because the charger meters every kW in and out, V2G programs usually pay on device data, not a whole-home baseline. That is the metering device output method in our M&V tutorial, with the same question of what the vehicle would have done anyway.

Upfront money matters as much as payments right now. PG&E’s V2X pilot pays $2,500 ($3,000 in disadvantaged communities), plus $1,500 for the first 250 enrollees, and requires enrollment in the Emergency Load Reduction Program (PG&E). MassCEC’s demonstration provides the charger and installation free through December 2026 (MassCEC). The federal 30C charger credit ended for property placed in service after June 30, 2026 (IRS).

Demand response or orchestrated VPP? Most residential V2G today is event-based demand response: Massachusetts calls about 45 summer events, and PG&E and Tesla’s California program use the Emergency Load Reduction Program. Tesla’s Texas program, through its retail electricity plan, discharges when wholesale prices are high, which is closer to an orchestrated VPP (Electrek). See how VPPs make money.

It depends on what is counted. Eleven research firms published 2025 V2G market estimates from about $16 million to $16 billion, with forecasts of $94 million to $185 billion in the early to mid-2030s. The gap is not mainly about growth: their annual growth rates cluster between about 21% and 40%. It is about what the market is.

For a VPP, the useful measure is not a market forecast but enrolled kilowatts times what a program pays for them. The IEA puts current owner benefits at several hundred to over $1,000 a year, with today’s commercial offers promising up to $770 (IEA). U.S. residential pilots still count enrolled vehicles in the dozens to hundreds, as the programs above show. These are gross payments, not net profit.

Event-based programs ask far less: about 45 events of under three hours a summer in Massachusetts (MassCEC). Heavier use costs more: earlier Hawai‘i Natural Energy Institute tests found once-daily V2G raised cell capacity loss by 33% (CleanTechnica). Warranty coverage is set by each automaker and program. Tesla, for example, says its Texas early-adopter grid program does not affect the Cybertruck warranty (Electrek).