Kia’s forthcoming EV 9 has the bidirectional capability. Hannah Elliott/Bloomberg

If you’re planning to buy an electric car in 2024, you’ll want to compare the models’ price, range, and charging speed. But you should also ask whether the car is capable of powering your home in a pinch. A growing number of EVs coming on the market can tap the considerable energy stored in their batteries to keep the lights on during a blackout and lower your utility bill when rates spike.

This “bidirectional charging” capability also promises to transform electric vehicles into a significant source of energy for utilities struggling to balance renewable energy production and climate-caused power disruptions. As EV sales grow, utilities can aggregate batteries into virtual power plants to avoid firing up fossil fuel power stations when demand spikes.

The 2.1 million electric vehicles now on the road in the US boast an estimated 126 gigawatt-hours of battery storage, according to a paper published in September by the nonprofit Smart Electric Power Alliance (SEPA). That’s five times the amount of battery storage currently connected to the grid.

“The need for backup power and resilience is becoming more front and center as we see more of these extreme weather events and grid outages in different areas in the US,” says Garrett Fitzgerald, a senior director at SEPA. California, for example, is routinely impacted by blackouts from wildfires and heat waves. A quarter of new car sales in the state are now electric, and EVs account for more than 40% of sales in some Bay Area zip codes.

When Ford Motor Co. launched its electric F-150 Lightning pick-up in 2022, the automaker touted the truck’s 131-kilowatt-hour battery pack, which can power a dwelling for days with the installation of a bidirectional charger and a home power-management system. A Tesla Powerwall home battery, on the other hand, generates 13.5 kWh.

“It’s basically 10 stationary battery storage units on one truck,” says Ryan O’Gorman, energy services business strategy lead at Ford. As more people work from home, bidirectional charging also lets vehicle owners capitalize on an expensive asset that would otherwise sit idle in their driveway, he adds.

Hyundai Motor Co.’s Ioniq 5 and Kia Corp.’s EV6 also feature bidirectional batteries, as does the EV 9, Kia’s forthcoming full-size SUV. General Motors Co. recently announced that its new line of Ultium electric vehicles will be bidirectional. The Nissan Leaf is bidirectional and Rivian has said its trucks and SUVs are equipped for two-way charging.

The elephant in the garage is Tesla Inc. The company, which sells 61% of electric vehicles in the US, has previously eschewed bidirectional charging. But at its March Investor Day event, Tesla executive Drew Baglino said he expected the company’s cars to be bidirectional-enabled within two years. “We’ve found ways to bring bidirectionality while actually reducing the cost of power electronics in the vehicle,” Baglino said.

Elon Musk, however, still seemed somewhat doubtful. “I don’t think many people are going to use bidirectional charging unless you have a Powerwall, because if you unplug your car your house goes dark,” he said at the investor meeting. Musk did allow that there’s “some value there as a supplemental energy source down the road.”

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Buying a bidirectional-capable car is just the first step to transforming your vehicle into a rolling power plant. There are varieties of two-way charging and the costs and benefits differ.

VEHICLE-TO-LOAD

V2L lets you power appliances and gadgets by plugging them into outlets in the vehicle – say, a coffee maker at a campsite, or electronic devices during a blackout at home. The extended range F-150 Lightning, for instance, is a mobile power strip, offering a 240-volt outlet in the truck bed along with four 120-volt outlets, two 120-volt outlets in the cab, and another four in the front trunk.

You don’t need extra equipment for V2L, except perhaps extension cords.

VEHICLE-TO-HOME

When Kia’s engineers began designing the EV6 back in 2016, they had their eye on eventually integrating the car into the home and then into the grid itself, according to Steve Kosowski, manager for long-range planning and strategy at Kia America.

“They saw that energy storage requirements were going to be huge as grids around the world started to shift to more and more sustainable energy,” he says. “Wind and solar really go hand-in-hand with storage, and that vehicle sitting on your driveway would be a really important part of that.”

The first step is to connect the car to a house’s electrical system so that when the grid goes out, the vehicle will automatically start supplying backup power. That requires the installation of a bidirectional charger plus hardware and software to manage power flows. If you have a rooftop solar array and a home battery, a home integration system can ensure that the car and battery are charged with solar energy during the day. At night or at other times when utility rates rise, the car and battery can supply any stored solar electricity to the home.

“Most electrons that were generated in the past were used at the point they’re generated, like when you turn on a light switch,” adds O’Gorman at Ford. “Now, with electric vehicles and storage, you have the ability to take that electron and hold it for a while and use it when it’s more” valuable.

Be forewarned, though: You’ll currently pay a premium to enable V2H. A charger and home integration system for the Ford F-150 Lightning, for instance, costs around $11,000 when installed by Sunrun, Ford’s preferred partner, according to SEPA. Installation of a conventional charger runs about $2,000.

Kia is working with Spanish company Wallbox Chargers to develop a bidirectional charger it expects to be available in 2025. GM in June announced a forthcoming suite of home integration products, including the “Ultium Home Energy System” which comes with a charger, an energy management system, and a stationary battery. Pricing has not been announced and GM didn’t respond to interview requests.

VEHICLE-TO-EVERYTHING

Some US utilities have launched pilot projects to test how electric vehicles can be incorporated into power grids. In California, Pacific Gas & Electric Co. aims to sign up 1,000 EV owners for a two-year V2X initiative. The first phase is underway with owners of F-150 Lightnings so that PG&E can evaluate the vehicles’ utility in powering homes and as a backup energy source.

F-150 Lightning participants must install a bidirectional charger and Sunrun’s home integration system in their homes. They receive $2,500 to help defray those costs as well as up to $2,175 in additional incentives. Owners of other bidirectional EVs will be eligible once PG&E vets the vehicles and other charging and energy management systems.

PG&E expects to begin connecting the EVs to the grid in 2024, which will require the installation of additional utility equipment. “We want to get a better understanding of how EVs can support the grid and better integrate renewables,” says Lydia Krefta, PG&E’s director for clean energy transportation.

The utility is currently devising a rate structure to compensate commercial customers who send electricity to the grid from their EV fleets.

With tens of millions of EVs expected to hit the road in the coming years, electricity demand is projected to double, Krefta says. One goal of the pilot project is to gather data on how tapping a virtual power plant of EV batteries can minimize the need to build additional infrastructure to charge those vehicles. The utility in particular wants to avoid constructing costly gas “peaker” plants that come online only when demand jumps.

Krefta notes that there are already enough EVs on the road in PG&E’s service territory to keep the city of Oakland’s 430,000 residents powered for three days. “We think that we could grow that to power Oakland for 25 days” by 2030, she says. “We can look to the flexibility that we have from electric vehicle batteries to decarbonize the grid at the lowest possible cost.”