Nov 30, 2023

Your EV battery can now power your home, yes really.

When the power went out at Nate Graham's New Mexico home last year, his family huddled around a fireplace in the cold and dark. Even the gas furnace was out, with no electricity for the fan. After failing to coax enough heat from the wood-burning fireplace, Graham's wife and two children decamped for the comfort of a relative's house until electricity returned two days later.

The next time the power failed, Graham was prepared. He had a power strip and a $150 inverter, a device that converts direct current from batteries into the alternating current needed to run appliances, hooked up to his new Chevy Bolt, an electric vehicle. The Bolt's battery powered his refrigerator, lights and other crucial devices with ease. As the rest of his neighborhood outside Albuquerque languished in darkness, Graham's family life continued virtually unchanged. "It was a complete game changer making power outages a nonissue," says Graham, 35, a manager at a software company. "It lasted a day-and-a-half, but it could have gone much longer."

Today, Graham primarily powers his home appliances with rooftop solar panels and, when the power goes out, his Chevy Bolt. He has cut his monthly energy bill from about $220 to $8 per month. "I’m not a rich person, but it was relatively easy," says Graham "You wind up in a magical position with no [natural] gas, no oil and no gasoline bill."

Graham is a preview of what some automakers are now promising anyone with an EV: An enormous home battery on wheels that can reverse the flow of electricity to power the entire home through the main electric panel.

Beyond serving as an emissions-free backup generator, the EV has the potential of revolutionizing the car's role in American society, transforming it from an enabler of a carbon-intensive existence into a key step in the nation's transition into renewable energy.

Home solar panels had already been chipping away at the United States’ centralized power system, forcing utilities to make electricity transfer a two-way street. More recently, home batteries have allowed households with solar arrays to become energy traders, recharging when electricity prices are low, replacing grid power when prices are high, and then selling electricity for a profit during peak hours.

But batteries are expensive. Using EVs makes this kind of home setup cheaper and a real possibility for more Americans.

So there may be a time, perhaps soon, when your car not only gets you from point A to point B, but also serves as the hub of your personal power plant.

I looked into new vehicles and hardware to answer the most common questions about how to power your home (and the grid) with your car.

America's grid is not in good shape. Prices are up and reliability is down. Since 2000, the number of major outages has risen from less than two dozen to more than 180 per year, based on federal data, the Wall Street Journal reports. The average utility customer in 2020 endured about eight hours of power interruptions, double the previous decade.

Utilities’ relationship with their customers is set to get even rockier. Residential electricity prices, which have risen 21 percent since 2008, are predicted to keep climbing as utilities spend more than $1 trillion upgrading infrastructure, erecting transmission lines for renewable energy and protecting against extreme weather.

U.S. homeowners, increasingly, are opting out. About 8 percent of them have installed solar panels. An increasing number are adding home batteries from companies such as LG, Tesla and Panasonic. These are essentially banks of battery cells, similar to those in your laptop, capable of storing energy and discharging electricity.

EnergySage, a renewable energy marketplace, says two-thirds of its customers now request battery quotes when soliciting bids for home solar panels, and about 15 percent install them. This setup allows homeowners to declare (at least partial) independence from the grid by storing and consuming solar power overnight, as well as supplying electricity during outages.

But it doesn't come cheap. The average home consumes about 20 kilowatt-hours per day, a measure of energy over time. That works out to about $15,000 for enough batteries on your wall to ensure a full day of backup power (although the net cost is lower after incentives and other potential savings).

An alternative is in the driveway. A typical EV stores about 67 kWh in its battery, more than three days’ worth of electricity, sitting unused (vehicles are parked for about 95 percent of their useful life). Until recently, the only way to tap it was by rigging an inverter system like Graham's. But bidirectional charging, the ability for vehicle electricity to flow both ways, is now a commercial reality in the United States. By 2024, numerous makes and models will be in dealerships.

You can even buy one today: The Ford F-150 Lightning, an all-electric version of America's best-selling pickup truck. It's scrambling the economics of home energy.

Ford changed how customers saw their trucks when it rolled out a hybrid version of the F-150, says Ryan O’Gorman of Ford's energy services program. The truck doubles as a generator sporting as many as 11 outlets spread around the vehicle, including a 240-volt outlet typically used for appliances like clothes dryers. During disasters like the 2021 ice storm that left millions of Texans without electricity, Ford dealers lent out their hybrid F-150s as home generators.

The Lightning, the fully electric version of the F-150, takes the next step by offering home backup power. Under each Lightning sits a massive 98 kWh to 131 kWh battery pack. That's enough energy, Ford estimates, to power a home for three days (10 days if rationing). "The vehicle has an immense amount of power to move that much metal down the road at 80 mph," says O’Gorman.

Instead of plugging appliances into the truck, the truck plugs into the house, replacing the grid. This requires some equipment: an 80-amp bidirectional charger and a home integration system, which is a hardware unit that allows you to disconnect your house from the grid and power it with the truck. Sunrun, the nation's largest residential solar installer, is Ford's preferred installation partner, although any licensed professional can install them.

Installing the extra hardware will cost about $5,000. (Ford includes the bidirectional charger with its premium models). Home wiring upgrades, or an optional solar array, would push the cost higher.

Even at that price, the F-150 may be the cheapest home battery on the market.

When battery prices surged last year because of rising demand and supply chain issues, automakers were first in line thanks to their enormous scale. That allowed them to make deals that appear to have radically undercut home battery prices.

Take the $56,000 F-150 Lightning. With the standard 98 kWh battery, it offers energy storage equivalent to seven Tesla PowerWalls ($15,500 each installed) for about half the price per kWh. So, for slightly over the U.S. median car price of $50,000, you get a home battery and a car.

For now, the Lightning only offers a house-size backup battery. But the next round of software upgrades will monitor home energy usage to decide the best time (and price) to recharge vehicles. During peak hours, it can disconnect your home from the electricity grid, relying on battery power, until prices fall.

Utilities across the country are also starting to allow EVs to supply electricity to the grid. Owners can opt into vehicle-to-grid services that allow utilities to call on their car's battery during peak demand, for a price. Sunrun CEO Mary Powell says the company has already received about 1,000 orders for the F-150's home battery systems around the country, particularly in places like California and Texas rocked by blackouts related to extreme weather (about 10 percent also opted to add solar).

Eventually, it aims to build a coordinated network as it does for home stationary batteries that could help balance the grid and power millions of homes. The potential is enormous. The Natural Resources Defense Council estimates that if, as expected, California's new clean air standards add 14 million zero-emission vehicles to garages by 2035, the collective battery storage could power all of California's homes for three days.

The idea is companies like Sunrun, along with utilities, will recruit vehicles like the F-150 Lightning to form virtual power plants. These networks of thousands or millions of devices can supply electricity during critical times. By 2030, according to the clean energy nonprofit RMI, this could reduce peak loads in the United States by 60 gigawatts, equivalent to the average consumption of 50 million households. That would cut the number of power plants we need to build, and help redistribute clean energy throughout the day.

Here's why. Think of today's electricity grid as a very expensive highway system with dozens of lanes crisscrossing the nation. Yet it's only at full capacity a few times a year. Because utilities must always keep the lights on, they invest billions of dollars in (polluting) power plants that may only operate for a few hours or even a few minutes each year. As the share of renewable energy increases, utilities may need even more of these plants to smooth out fluctuations when the wind or sun isn't available.

Batteries offer an alternative. By storing energy and dispatching it at the right time, they can help utilities ramp up renewables without expensive new natural gas plants as a backup.

Still, using an EV as a home battery might not be the best way to cut your overall emissions, especially if you buy an oversize one. (The new Hummer EV, for example, pollutes more per mile than small gas-powered sedans).

The most effective way to zero out emissions, researchers argue, is reducing personal dependence on cars. Mass transit, cycling, walkability, better zoning and land use planning are all necessary to hit emission reduction targets in the transportation sector, which is now the largest source of U.S. emissions, even as EVs replace their fossil fuel counterparts.

But cities won't develop walkable designs and ubiquitous transit systems overnight — if they ever do. America was built for cars: 93 percent of U.S. households own a vehicle.

So if you aren't getting rid of your vehicle, you’ll face new choices the next time you walk into a car dealership: How do you want to power your home and the grid?

Many of the EVs rolling off assembly lines today will give you that option, says Douglas Alfaro of WallBox, an EV charging and energy management company. The company is partnering with automakers to design hardware that works with almost any vehicle — Ford's charging infrastructure, so far, is proprietary. This is already starting to happen: Makers of the Hyundai Ioniq 5, Lucid Air, Kia EV6, VW's ID.4, Mitsubishi Outlander, and Chevy Silverado EV have announced they will offer home electricity services in the next year or so.

As Graham realized after his last power outage in New Mexico, electrifying your life means rethinking how your vehicle is connected to everything else. In the future, our cars will be plugged into our homes and other intelligent devices, trading electricity with each other and the outside world.

A previous version of this article incorrectly referred to a device as an 80-watt bidirectional charger. It is an 80-amp bidirectional charger. The article has been corrected.