Could the energy stored in an electric vehicle be used to supply electricity to the grid? Absolutely — it’s already happening. Several vehicle-to-grid (V2G) pilot projects are already underway in the United States, including trials by Toyota and General Motors. They join a host of even larger pilots, including three ongoing projects by the Pacific Gas and Electric Company (PG&E) in California to trial V2G in homes, businesses and microgrids.

The potential is enormous. V2G allows homes to become what Bloomberg calls “mini power plants” in its report on KB Home’s new microgrid community near Los Angeles. Armed with rooftop solar, an EV and a bidirectional charger, homeowners can not only keep their own lights on during a blackout, they can help sustain the entire power grid. In exchange, the electricity they sell to the grid helps lower their power bill by as much as $15,000 over 10 years. “What homeowners are looking for in their home energy are two things: one is reliability and the other is predictable low cost,” KB Home CEO Jacob Atalla told us earlier this year. V2G is a big step forward in achieving that.

A more stable grid

The big picture is just as encouraging. With enough businesses and homes making use of V2G charging, utilities would have access to a vast reserve of backup energy, helping make power grids more reliable at a time when increasingly severe and unpredictable weather events are posing a major challenge. “EVs can represent a tremendous strain on the grid if it’s single directional, but those same EVs can be a tremendous benefit,” says John Wheeler, co-founder and CFO of Fermata Energy, which makes EV chargers for businesses. “EVs can be a solution – they are literally mobile distributed energy storage.”

New research from the UK suggests that V2G will be instrumental in making power grids more adaptable and more resilient. But things aren’t quite there yet. “I’m a big proponent of V2G — I think this is the future. But so far it is largely a pilot at best,” says Alex Bhazinov, CEO of Lumin, which helps homeowners manage their home energy systems. “It’s such a new thing it barely exists,” he adds, noting that many of the contractors his company deals with aren’t even familiar with the concept of bidirectional charging. But Bhazinov thinks it’s just a matter of time before V2G becomes widespread. “It’s just starting out, but eventually it will become ubiquitous.”

The cars are catching up

V2G will have to clear a number of roadblocks before that can happen. The first hurdle is EV charging technology itself. Not every EV is capable of bidirectional charging, and while this is changing, the floodgates haven’t yet opened. Perhaps most notably, the world’s best-selling brand of electric cars, Tesla, does not allow bidirectional charging, reportedly because of concerns over the impact it would have on the performance of the vehicle’s battery. (The company recently suggested it could change course, opening up the possibility of bidirectional charging for Teslas by 2025, even though founder Elon Musk dismissed the usefulness of vehicle-to-home or V2G charging without a suitable interface.)

Research has shown that bidirectional charging doesn’t harm batteries, which will likely convince more and more automakers to embrace bidirectional charging. “This was a big deal for a long time. It still is a big deal,” says Wheeler, who notes that charging software can now regulate the flow of energy to and from an EV so that battery life isn’t negatively affected. “We don’t want to destroy the core function of the vehicle, which is to drive people around,” he says.

“There’s quite a bit of data coming out on this now. It’s actually better for your vehicle battery for it to be cycled than to just be left in the driveway,” says dcbel founder Dan Fletcher. But it’s important to have the right charging platform to be able to harness bidirectional charging as efficiently as possible – something like the dcbel r16 Home Energy Station. “We have the specs of the battery embedded in the setup,” says Fletcher. “And then we have the ability to do what the battery likes and not do what the battery doesn’t like.”

Beyond the cars, there’s also the matter of EV chargers themselves. Most EVs come equipped with a standard Combined Charging System (CCS) charging port, which combines AC and DC pins. This simple and convenient standard has already won the charging “format war” here in North America, with the Nissan Leaf and Mitsubishi Outlander plug-in hybrid being the lone holdouts. The standard those two cars are clinging to is called CHAdeMO which, unlike CCS, supports bidirectional power flow over DC from the get-go. This means that the vast majority of EVs on the road won’t be able to plug-and-play with V2G until the protocol’s governing body, Charin, updates the standard sometime during the next couple of years.

“We feel strongly that the majority of EV manufacturers will be supporting bidirectional use of their vehicles on a DC pathway,” says Fletcher. But once again, that evolution will come with the need to adopt the right platform for their car if owners want to take advantage of bidirectional charging.

“It’s one thing for a vehicle to have some plugs in it so you can charge a worksite or a tailgate party, and it’s another thing completely to use it to power a home,” he says. “It gets even trickier beyond that because when there’s a blackout and the grid is down, you need something creating the AC waveform in the house. You need to manage the supply and demand of energy in real time. So just having a car that is bidirectional is not going to get you all that you want.” You need the right platform with the right software.

It’s up to the utilities

Once more EVs are capable of bidirectional charging, and more bidirectional charging platforms like the dcbel r16 reach the masses, the biggest challenge facing V2G doesn’t come from the V part of the equation — it’s the G. As utilities dip their toes in the water through pilot projects, they’re realizing they need to get their own houses in order before they can adopt V2G on a larger scale. A recent webinar hosted by the California Energy Commission (CEC) and ElaadNL, an EV charging innovation center run by a coalition of Dutch utilities, reveals some of the roadblocks facing grid operators when it comes to V2G.

“For many of you who need to connect to the electricity grid for charging infrastructure, you may think, ‘Well, how hard can it be?’” says Lonneke Driessen, director of standardization at ElaadNL. Quite hard, as it turns out. Both in Europe and North America, the diversity of codes governing the operation of power grids is posing an obstacle to V2G adoption. Jeffrey Lu, who works on vehicle-grid integration for the CEC, describes the situation as a “stalemate” that needs to be overcome by updating and harmonizing grid codes — the only way to “support greater V2G adoption, implementation and economies of scale.”

Cost is also an issue. Christopher Moris, principal for grid innovation at PG&E, notes that one of the utility’s recent V2G pilot projects saw most homeowners pay between $10,000 and $18,000 for wiring, panel upgrades and EV chargers — but one homeowner was billed $58,000 because trench work was required to update their home’s 100-amp service. Moris says there needs to be more collaboration between EV manufacturers, charging vendors and utilities to streamline this process and avoid unexpectedly high costs for homeowners interested in V2G.

This is to say nothing of the interconnection delays that have been plaguing certain grid operators across the US. Faced with a backlog of interconnection requests from new solar projects, the country’s largest grid operator, PJM, which serves 65 million people across the eastern US, has suspended new interconnections for two years while it tries to catch up and reform its system. In many states, this could be a setback for any attempt to introduce wide-scale V2G charging, at least in the short term.

PG&E seems optimistic about the results of its pilot projects. Last October, the company unveiled a new V2G export rate for commercial electric vehicles, laying the groundwork for a future expansion to the residential space. It also provides a model for utilities across the US, as California is the nation’s largest EV market. “Leveraging the capability of EVs as a grid resource will help integrate more clean energy into our power system, reduce energy bills for all utility customers, and support California’s ambitious decarbonization goals,” said Ed Burgess, policy director of the Vehicle-Grid Integration Council, in response to PG&E’s new rate structure.

A bright future

When that happens, the pilot projects suggest a promising scenario for consumers and utilities alike. Fermata Energy is currently working with urban mobility company Revel and clean energy company NineDot on a V2G pilot in Brooklyn. It started in response to a conundrum discovered by NineDot, which is working to create community-based distributed energy resources. “You can’t put a big battery in a building in New York City because of the fire code,” says John Wheeler. But you can park an EV inside a garage and use it to both power a building and feed the grid. After all, says Wheeler, “EVs are just batteries on wheels.”

Making use of its own EV charging platform and Revel’s fleet of Nissan Leafs, Fermata Energy was able to create Brooklyn’s first commercial V2G interconnection. It provided most of its energy to the grid in the month of August, when demand was at its highest thanks to air conditioning usage. “We made 12 to 15 dollars an hour discharging energy back into the grid,” says Wheeler. At the same time, the company also used its Leafs as a source of backup energy for a building in the Brooklyn Navy Yard, which came in handy during a blackout caused by Hurricane Ida on September 1, 2022. “We had a Nissan Leaf powering the entire building,” says Wheeler. “It supported that load all through the night.”

Wheeler notes that the biggest hurdle to setting up the pilot project was dealing with interconnection bureaucracy. “You get a form, you tick a bunch of boxes, but there’s no box that says ‘vehicle to grid,’” he says. “But it’s getting better.” More and more utilities are aware of the potential of V2G — and the more pilot projects that take place, the more likely it can be rolled out to the average EV owner. “It’s no longer a ‘this might happen in 10 years’ thing,” says Wheeler. It’s happening. And for homeowners with solar and an EV, it will mean more cash in their pocket and confidence that their home — and the electrical grid as a whole — can withstand even the most unexpected events.