Electric cars store large amounts of energy in their battery banks that is used to drive the car. But in principle, parked electric cars could be used as mobile energy storage networks. The energy in cars could be given back to the power grid – a technology known as vehicle-to-grid or V2G. Alternatively, the stored energy in a car could supply electricity directly to a home, for example during a power outage. This is V2H.
There is enough energy stored in today’s EVs to power a typical home for a least a few days. In places that offer heavily discounted off-peak electricity pricing, an EV could charge up during off-peak hours and then power a house during peak hours. If lots of cars participate in V2G, it can be used to stabilize the grid and reduce the need for expensive, polluting peaker plants in times of high demand.
Only some EVs currently have the required circuitry and software for V2G and V2H and very few homes are equipped for it. A company called Bidirectional Energy in California is installing equipment for these functions in 120 homes in a state-funded pilot program. The goal is to establish the rules of the road for these installations so that standards can be set just as they have been for ordinary EV chargers and home backup batteries.
Establishing this technology as a mainstream activity will require standardization and this program is a step in that direction. In a world where electric cars are dominant, bidirectional charging makes abundant sense and will be beneficial to car owners, home owners, and society in general.
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In this house, an EV helps power appliances — and the grid
