The secret to a better grid? Electric vehicles.

A coalition of utilities and energy companies — Eversource, National Grid, EnergyHub, Sunrun, and the Mobility House — is launching an early test in Massachusetts of vehicle-to-grid technology, or V2G, which lets electric vehicles send power back into the electric grid, not just draw from it. Participants join an existing program called ConnectedSolutions, and during "demand response" events, like a heat wave, their EV batteries help supply the grid. In exchange, owners get paid, similar to homeowners who sell back solar power. The discharging only happens for a small number of hours a year, not daily.

To take part, you need a bidirectional charger, hardware that lets electricity flow both ways between your car and your house or the grid. Not all EVs support this yet, though more models, including the Nissan Leaf, are being built with it. An EV battery holds roughly six times the capacity of a typical home backup battery, and only a fraction of owners in an area would need to participate for the system to help meaningfully, since utilities can pool many batteries together.

For homeowners, this isn't an upgrade you need to make now, but it points to where things are headed: EVs increasingly doubling as backup power sources that can earn their owners money while easing strain on the grid during peak demand. As bidirectional chargers get cheaper and more common over the next few years, this kind of program may become more widely available beyond Massachusetts.