The multi-billion dollar promise of vehicle-to-grid integration

Electric cars sit parked most of the time, and their batteries hold a lot of unused power. A Kia EV9 battery, for example, can store as much energy as about seven home backup batteries. Vehicle-to-grid technology, or V2G, lets a car send that stored power back to your home or the grid instead of just drawing power from it. Automakers are now building more cars that can do this, including the Tesla Cybertruck, Ford F-150 Lightning, GM electric vehicles, and the Kia EV9 when paired with a compatible charger.

The catch is cost and payoff. A bidirectional charging setup that lets a car send power out, not just take it in, can run several thousand dollars to install. Using that setup to power your home during an outage, instead of buying a whole-home generator, already looks like a reasonable trade financially. Selling power back to the grid for money is a different story: in most places, utilities don't yet pay enough to make it worth the upfront cost, though some programs in California, Massachusetts, New York, Maryland, Colorado, and Connecticut are starting to offer payments for this kind of grid support.

There are also open questions about whether sending power back and forth wears down a car's battery faster or affects the manufacturer's warranty. So far only a couple of automakers have addressed this directly in writing. Given all this, V2G today makes more sense as home backup power than as a way to earn money from your utility, though that could change as more utility programs and financing options appear.