GM and PG&E to test how EVs can power homes during blackouts

Despite the hype from automakers, vehicle-to-home charging is in its infancy. What will it take to scale?
By Jeff St. John

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A woman in a dark blue winter coat charges a small white car in the driveway of a home
(Tesson/Andia/Universal Images Group via Getty Images)

Using electric vehicles for backup power during blackouts has lately become a hot topic. Ford has made the concept a central selling point of its F-150 Lightning battery-powered pickup truck. Automakers, EV-charging manufacturers and energy services companies are eagerly promoting the role of vehicle-to-grid” technology not only to keep the lights on during outages but also to help balance power grids when they are up and running.

But there’s a lot of technical and regulatory work to be done to make this concept a mass-market reality. How will different EV chargers handle two-way power flows? How can homes balance their energy demands without depleting EV battery capacity? And what’s the role for utilities, which are responsible for ensuring that backup power sources are connected and operated safely?

These are among the questions that California utility Pacific Gas & Electric and automaker General Motors plan to answer together. Over the course of 2022, the two will run a pilot project that will put multiple GM EVs in the role of backup generators, first in the lab and then in actual homes.

Using charging hardware from an as-yet-undisclosed partner and GM’s own software-defined communications between EVs and homes, the project will allow power to flow from an EV to customer’s home, do it automatically, and [be] carefully coordinated behind the scenes,” Rick Spina, GM’s vice president of EV infrastructure, said during a Monday press briefing.

The pilot is designed so that we can scale it significantly,” he added. GM plans to have everything in our fleet” ready to provide home backup power as the company gears up to offer 30 new EVs by 2025 and shift entirely to an all-zero-emissions lineup by 2035, he said.

For PG&E, using EVs for backup power can help serve multiple needs, said Aaron August, the utility’s vice president of business development and customer engagement. PG&E’s Northern and Central California service territory is home to one in five EVs in the U.S. today, more than any other utility in the country. It’s spending hundreds of millions of dollars to make its grid ready to serve even more EVs as California makes its mandated shift to zero-emissions vehicles over the coming decades.

But the utility is also desperately seeking ways to power customers through the wildfire-prevention grid outages it’s been forced to impose over the past several years, as well as to reduce grid strain during summer heat waves like those that forced the state to institute rolling blackouts in August 2020. Finding ways to use EVs to make power outages invisible” — and to build on that vehicle-to-home” capability to eventually serve wider grid needs — is appealing under these circumstances, he said.

Getting the standards in place for mass-market vehicle-to-home charging

But PG&E and GM aren’t yet ready to say when this capability will become a standard part of their vehicle and utility repertoire, or how much vehicle-to-home capable systems might cost compared to standard EV chargers.

We really need to prove it out in the lab environment first,” August said. 

That uncertainty remains despite more than a decade of tests that indicate that EVs are quite capable of powering homes and buildings, as well as the grid at large, said Sunil Chhaya, senior technical executive for EV integration with the utility-funded research organization Electric Power Research Institute.

EPRI worked with GM on a U.S. Energy Department–funded vehicle-to-grid project back in 2009, and we’ve had at least three projects since 2015 where we’ve worked on this seriously,” Chhaya said. But until recently, there haven’t been enough EVs in U.S. garages to make bidirectional charging a priority for automakers and utilities.

That’s not to say that bidirectional charging hasn’t been rolled out at large scale anywhere else. Japan has made vehicle-to-home capability an increasingly standard feature of EVs sold domestically, a result of its fast-tracked effort to back up homes after the 2011 earthquake and tsunami that destroyed the Fukushima power plant and led to a nationwide power crisis.

But the U.S. can’t replicate what Japan has done. Japan has standardized on a fast-charging technology known as CHAdeMO, while the United States uses an alternative technology for fast chargers, CCS, that hasn’t yet developed bidirectional charging standards.

Chhaya noted that international standards bodies are close to formalizing a standard known as ISO 15118 to manage bidirectional charging and communications for CCS charging systems. But because it’s not yet complete, every current implementation is proprietary,” he said. That includes the well-advertised partnership between Ford, solar and battery vendor Sunrun and electrical equipment maker Siemens on the Ford Charge Station Pro system that can allow a Ford F-150 Lightning to power homes.

Utilities and local permitting agencies aren’t eager to support the widespread installation of technologies in the absence of uniform standards, he said. They much prefer uniform requirements that allow everything to know exactly how to behave when they’re connected to the grid.”

Another challenge is that the standards developed for direct-current (DC) charging, which is typically used for fast-charging stations, need to be adapted for home charging in the U.S., which typically relies on grid and household alternating current (AC) that’s converted to battery-ready DC in the vehicle itself, Chhaya noted. The Level 1 and Level 2 chargers most commonly used in homes today aren’t designed to support two-way power flows and the communications needed to coordinate them, and those that are, such as new models from Fermata Energy and Wallbox, are just being brought to market in the U.S. today.

For these EV chargers to actually power a home when the grid is down, they have to be able to serve as a grid-forming inverter,” setting the voltage and frequency of alternating current to keep household appliances functioning properly, Chhaya added. They also have to ensure that they won’t accidentally energize power grids during an outage, which could endanger utility workers who are trying to restore power. These are additional layers of complexity that come with additional costs.

Spina declined to name the company that GM and PG&E will be working with to provide the EV chargers and power-conversion equipment for its vehicle-to-home charging pilot. But he did note that the predominant cost challenge” to bidirectional charging will be determined by the cost and complexity of this technology in the middle.”

Making it worth the effort for automakers and EV-charging providers

Chhaya highlighted another reason why vehicle-to-home and vehicle-to-grid technologies haven’t taken off yet in the U.S. Until recently, there wasn’t enough demand for EVs, or frequent enough grid outages, to drive automakers to invest heavily in technology that could turn those EVs into backup power resources.

PG&E has previously run lab tests that indicate EVs can supply power to homes and the grid. But the report on those tests, published in early 2018, noted that the lack of commercially available technologies” and high upfront costs for them limited the value of investing in this space until EV makers and charging vendors worked out cost and interoperability issues.

That’s all changed pretty dramatically in the past few years, however. California, the country’s leading EV market, has suffered through years of fire-prevention power outages, as well as continued risk of seeing summertime electricity demand outstrip the grid’s ability to supply it.

The grid threats haven’t been confined to California. During last year’s widespread winter power outages in Texas, reports of people powering their homes with the generators onboard Ford F-150 hybrid trucks helped spur interest in using EVs in emergencies and provided inspiration for Ford to highlight the backup capabilities of its all-electric Lightning in its marketing rollout later that year.

Utilities and state regulators have also been moving more quickly to come up with policies that could allow EVs to serve as backup power sources. California recently revised its interconnection rules to include vehicle-to-grid systems. August noted that PG&E’s project with GM would be funded as part of a broader set of vehicle-grid integration” projects it’s planning to run over the coming years — if they’re approved by the California Public Utilities Commission.

Similar vehicle-to-grid pilot projects are underway or being proposed in California, New York and other areas across the country. Spina said that GM is working on a number of pilot projects with utilities in the Midwest and mid-Atlantic region, although he didn’t provide further details.

Most of these vehicle-to-grid projects are focused on connecting fleets of electric buses, vans and trucks rather than consumer vehicles. That’s partly because owners of such fleets have set operating schedules that are better suited to being tapped as backup power or grid resources, and partly because economies of scale favor projects that can aggregate lots of bigger vehicles using the same technology.

It’s important to make sure vehicle-to-home charging systems don’t leave EV batteries too depleted to meet the driving needs of their owners. Spina noted that a typical home’s daily electricity needs are much smaller than a typical EV’s battery capacity, leaving ample charge to cover outages of a few hours, and potentially even a few days. GM will limit how deeply an EV battery will be discharged to meet household needs during the PG&E project, he said.

EV buyers also tend to be more likely to install rooftop solar systems or backup battery systems, making them a target for companies that are seeking to enlist homes as resources to support the grid.

Last week, long-time vehicle-to-grid technology provider Nuvve announced it is working with Swell, a startup that’s aggregating solar- and battery-equipped homes in California, Hawaii, New York and other states, to integrate bidirectional EV charging into Swell’s virtual power plant projects.

The capacity of batteries on the road is already much larger than the capacity of stationary batteries,” Nuvve CEO and Chair Gregory Poilasne said in an interview last week. We see loads, storage and vehicles working together.”

PG&E is also interested in exploring the potential for EVs to help reduce grid stress, August said. That might start with tapping EV batteries not just during power outages but when the grid could use their support so that homes can reduce their draw on the grid. PG&E and other utilities are already asking EV owners to delay charging during hours of peak grid demand through various incentives and electricity pricing structures, in order to manage what’s expected to be the fastest-growing source of load on their power grids.

But August cautioned that the pilot project with GM isn’t yet taking on the complexities that accompany that kind of use of EV batteries, such as how to pay customers for the grid value they would provide or how to manage the operations of lots of EVs across entire neighborhoods or regions.

That’s exactly why this particular program is focused on the vehicle to the home,” he said. When you start to go beyond the home and into vehicle-to-grid, you’re starting to orchestrate in a much broader way.” 

Jeff St. John is director of news and special projects at Canary Media. He covers innovative grid technologies, rooftop solar and batteries, clean hydrogen, EV charging and more.