While an industry shift to electric vehicles will obviously introduce new demands for more electricity, the use of bidirectional chargers can mean that EVs can provide a buffer for the grid during times of high demand.

Overnight, when air conditioning demands are lower because of cooler temperatures, EVs can charge while the electric grid has a chance to catch its breath. Then, during the day, the batteries of millions of EVs can pour electrons back onto the grid to help run air conditioners during the hours when ambient temperatures are breaking records.

EV owners have more than altruism to motivate them to install bidirectional chargers. Electric grid operators will pay owners for the buffering effect their vehicles provide. According to the U.S. Dept. of Energy, the University of Delaware earns $1,200 a year for plugging in each of its EVs with a bidirectional charger. “By being prepared to act as a mobile battery to charge/discharge as a demand response asset, the battery electric vehicles (BEVs) generate revenue which aids in justifying the capital costs of the BEVs and the associated support infrastructure,” states the DOE report.

Vermont Energy Investment Corporation transportation policy manager Ingrid Malmgren estimates that consumers could expect to earn more like $400 a year, with lifetime earnings for an EV reaching about $5,000.

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There is a difference between more common “smart” EV chargers and bidirectional chargers. According to charger manufacturer Wallbox, a smart charger is one that lets owners schedule their vehicle’s charging time and rate to potentially take advantage of less-expensive overnight charging. “With smart charging, cars can be plugged in but they don’t have to actually be charging the whole time,” states a Wallbox post on the company’s blog. “Instead, individual EV owners or energy companies can decide when it’s most efficient to charge energy in terms of demand and cost, depending on the country and the energy operator.”

Two-way bidirectional charging, on the other hand, lets power flow from the car’s battery back to the power grid. In the case of systems like Ford’s Charge Station Pro, when connected to the F-150 Lightning pickup truck, bidirectional charging can be used to power the owner’s home in the event of a power outage.

Or, the charger can actually send power back to the electric grid, in the same way that home solar panels are often wired to do. “With careful planning and the right infrastructure, parked and plugged-in EVs could become mass power banks, stabilizing the electric grids of the future,” said the Wallbox blog. “In this way, we can think of EVs as big batteries on wheels, helping to make sure that there is always enough energy for everyone at any given time.”

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Today, there are too few bidirectional EV chargers installed to help ease the strain on California’s grid for the current heat wave. But bidirectional chargers let EVs help keep the lights on and the air conditioners humming through future weather events if the potential benefits are made clear to consumers when they are buying their first home EV charging stations.