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June 26, 2023
5 Min Read
An Electrify America electric vehicle charging station in Monterey Park, California.Frederic J. Brown/Getty Images
The state of California is considering a bill that would require electric vehicles and their charging stations in the state to support bidirectional charging. This is when electricity can flow from the electric power grid to the car and also back again from the car to the grid or to an EV driver’s house.
That means that energy stored in a vehicle’s battery can be tapped as needed to help balance the load on the utility grid during times of high demand for electricity or it can power an owner’s home in the event of a power failure.
EV critics complain that demand from electric vehicles will over-stress an already fragile electric grid, but bidirectional chargers and cars that are compatible with them can actually make the grid more resilient, said Mike Austin, senior research analyst for electric vehicles at Guidehouse Insights.
“The benefit is that bi-directional vehicles and chargers can potentially reduce the peak load on the electrical grid, possibly even to a greater degree than EVs will add,” he said. “This also helps take greater advantage of renewable energy because you’re not just charging EVs with excess capacity but you can put that energy back into the grid when needed.”
Vehicles spend 95 percent of their time parked, according to the International Renewable Energy Agency, making EV batteries an untapped resource until they can return their stored power to the grid as needed. “With careful planning and the right infrastructure, parked and plugged-in EVs could become mass power banks, stabilizing the electric grids of the future,” stated EV charging station manufacturer Wallbox in a post on the company’s blog.
The California bill sets a deadline of June 30, 2024, for the state to establish a “workgroup to examine challenges and opportunities associated with using an electric vehicle as a mobile battery to power a home or building or providing electricity to the electrical grid.”
That group will be required to produce a report to the governor and state legislature by January 1, 2026, to submit a report to the Governor and Legislature detailing the bidirectional capability of electric vehicles and electric vehicle service equipment. Beginning in the model year 2030, all new electric vehicles sold in California would be bidirectional-capable, including light-duty motor vehicles and school buses, except as exempted by the state board.
This timetable is probably short in the world of government bureaucracy, but events seem likely to overtake this schedule as carmakers roll out advances as quickly as possible. With the 2030 model year cars six years away, they will probably already include the technology, predicted Austin. “It’s likely that bidirectional-capable vehicles will be pretty standard by 2030 anyway,” he said.
As the largest seller of EVs in the U.S., Tesla will determine how quickly the car industry shifts to bidirectional charging. At this year’s Tesla Investor Day in March senior vice president of powertrain and energy engineering, Drew Baglino, told investors that the company is shifting its vehicles to support that capability. “It wasn't like a conscious decision to not do it,” he said. “It just wasn't a priority at the time,” he said.
But now Tesla has recognized the value of providing this capability, he said. “As we continue to improve the power electronics in our vehicle we've found ways to bring broader actionality while actually reducing cost of power electronics in the vehicle,” Baglino explained. “We are in the middle of kind of like a power electronics retool, I would say, that will bring that functionality to all of our vehicles over the next, you know, two years, let's say.”
The Wallbox Quasar home EV charging station features bidirectional charging capability.
Infrastructure is Everything
The issue, as with so many concerns about the electrification of the light vehicle fleet, is the charging infrastructure. “The needed push here is in bidirectional charging equipment,” said Austin. “If businesses are planning on a ten-year lifetime, based on depreciation, for charging equipment, that means every uni-directional charger installed delays another bidirectional charger,” he pointed out. “If the chargers are already in place, it will vastly increase the usefulness when the vehicles and grid are ready.”
The question is how much more such chargers will cost than today’s unidirectional chargers. The current dearth of bidirectional chargers makes the extra cost difficult to estimate, said Austin. “There really isn’t that much equipment out there,” he said. “That also makes it hard for any economies of scale to bring costs down. That stands for L2 as well as DC fast [chargers].”
The Ford F-150 Lightning pickup truck is currently the only model for sale in the U.S. that can power a home, through its Charge Station Pro and the Home Integration System. The Hyundai Ioniq 5 and Ioniq 6, Kia EV6, and Mitsubishi Outlander plug-in hybrid-electric vehicle are the only other vehicles currently for sale that claim bidirectional capability. But currently, those vehicles provide a fraction of the power the Lightning can, so they serve to run a few individual tools or appliances rather than an entire home, much less send power to the grid.
However, the ability to run power tools has proved to be unexpectedly popular among Lightning buyers, according to Ford CEO Jim Farley, who spoke on the Fully Charged podcast. “We didn’t know that a mobile battery on a worksite was going to be that evocative,” said Farley. “The exportable power turns out to be the main reason people are excited about the Lightning.”
Renault has announced its intention to add bidirectional charging to its vehicles through the company’s e-mobility brand, Mobilize. The Renault 5 will be the company’s first EV to support bidirectional charging.
“Thanks to Mobilize [vehicle-to-grid], cars become an energy reserve,” said Corinne Frasson, Director of Energy Services at Mobilize. “All drivers have to do is regularly connect their vehicle to the Powerbox to optimize their electricity bill and cut carbon from their mobility. On average, the cost of charging is cut by half.”
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