Your electric car could become a virtual power plant

That electric car parked in your driveway may soon be more than a fun, emissions-free ride. When lashed together in the cloud with other EVs in your neighborhood, it could help utilities manage electricity demand in your community.

Why it matters: Massive growth in electric vehicle adoption — which is widely expected — means that more car owners will be plugging in at home, putting pressure on America's electric grid but creating power-sharing opportunities at the same time.

• Emerging smart-charging technologies aim to build in more flexibility so grid upgrades aren't needed and EV owners will have all the juice they need.

What's happening: EV owners can earn rebates and cash rewards from smart-charging programs by letting utilities control when their car is charged based on overall electricity demand.

• In Texas, for example, about 1,000 EV owners participate in a smart-charging project with the Electric Reliability Council of Texas (ERCOT).
• Together, those cars serve as a cloud-based "virtual power plant" that ERCOT can use to suck or store energy during demand peaks and valleys.
• In Wisconsin, Madison Gas and Electric shifts charging times for 200 EVs to off-peak hours so they can soak up renewable energy generated overnight by wind farms.
• Both utilities license the smart-charging technology from a London-based company called ev.energy, which has offices in Palo Alto.

The big picture: EV owners do more than 80% of their charging at home, according to a BloombergNEF analysis of ev.energy data from more than 1 million at-home charging sessions in the U.S., U.K. and Europe.

• Most of them plug in after work, start charging right away, and stay plugged in overnight, often setting the departure time for their morning commute.

Yes, but: The typical charging session requires just a little top-off — 2.5 hours of charging — which means most EVs are drawing energy in the early evening when residential demand is at its peak and electricity rates are highest.

Smart-charging technology can delay charging until demand has gone down, and greener, cheaper energy is more readily available.

• That lets utilities balance electricity demand while also maximizing the use of renewable energy and putting more money in EV owners' pockets.

• An EV owner in California could save an estimated $600 per year charging at off-peak times, BNEF found.

How it works: EV owners plug in their car, set a departure time using ev.energy's app, and let the utility figure out the ideal charging time based on a 24-hour forecast of energy demand.

• If necessary, the software will pause charging at the utility's request, then resume later.
• Car owners' flexibility earns them rebates or cash rewards of $5 or $10 a month.

The utility will never drain the car's battery, says Joseph Vellone, head of North America for ev.energy. "Your departure time is the holy grail."

• "The electricity system is incredibly complex. EV buyers can’t be bothered to immerse themselves in this complexity. We ask them one question: What time do you need your car charged by?"

Editor's note: This story has been corrected to show that Madison Gas and Electric shifts charging times for 200 EVs to off-peak hours for maximum efficiency, not 2,000 EVs. A partner company, ev.energy, reached out to say there was a numerical mistake in the report it shared with Axios.