TIME energy

Electric Cars Will Change the Way You Power Your Home

An electric charging cable is seen connected to the updated Nissan Leaf vehicle during a news conference in Japan, Tokyo, on Tuesday, Nov. 20, 2012.
An electric charging cable is seen connected to the updated Nissan Leaf vehicle during a news conference in Japan, Tokyo, on Tuesday, Nov. 20, 2012. Kiyoshi Ota—Bloomberg/Getty Images

How the homes of the future will generate and store their own electricity, turning your house into a mini-power plant

Electric vehicles are our fastest-growing alternative to oil-derived gasoline. Solar panels are our fastest-growing alternative to coal-powered electricity. They’re both getting less expensive and more effective, driving our clean-energy revolution. And there’s new evidence that these two great tastes can taste particularly great together, transforming how we consume and produce power in ways that will accelerate that green revolution.

The evidence comes from Opower, a firm that uses software and behavioral science to help utilities promote energy conservation — and has amassed the world’s largest storehouse of household energy data along the way. Opower studied the power-consumption habits of about 2,000 plug-in electric-vehicle owners enrolled in “time-of-use” pricing programs. That means they got discounted electricity rates from midnight to 7 a.m., when demand is typically low, but paid a surcharge during peak daytime hours, when demand tends to spike.

Grid managers have to balance supply and demand every second, so big gaps between peak and off-peak demand can create big inefficiencies by forcing them to turn power plants on and off to adjust supply. In theory, the combination of electric vehicles (which can be charged anytime) and time-of-use pricing (which encourages charging after midnight) could help reduce those gaps. It could also help prevent electric vehicles (which alleviate the problem of carbon emissions) from exacerbating the problem of overloaded daytime grids. And that’s basically what the data showed — with a twist.

Opower found that EV owners did respond to the incentives to charge during off-peak hours, using three times as much power as the typical household between midnight and 7 a.m. It’s notoriously tough to get consumers to adjust their behavior, even when it’s in their financial interest, so that’s good news. At first glance, the data from the rest of the day looks like bad news: from 7 a.m. until midnight, EV owners still used 21% more power than the typical household. But this was mainly because they’re richer than the typical household; their houses were bigger and more likely to have a swimming pool. They clearly did the bulk of their vehicle charging after midnight when power was cheap.

The most striking data was from EV owners who also had solar panels. From 7 a.m. to midnight, they used about one-fourth as much power from the grid as the typical household, because they were getting power from their rooftops and often selling power back to the grid. In other words, they took very little from the grid when demand was high — at times even helping to increase supply — and took much more from the grid when demand was low. They helped smooth out demand.

That’s very good news, not only because smoothing out demand is a kind of holy grail for utilities, but because EV owners were 6.6 times more likely to have solar panels than the typical household. Nancy Pfund, a venture capitalist who invested early in Tesla Motors, the hottest EV firm, and Solar City, the leading solar installer, calls EVs “the gateway drug to solar.” Once you stop using hydrocarbons to fuel your car, she says, you want to stop using hydrocarbons, period. “Together, they can be a huge tool for managing our energy load,” Pfund says. “And they’re both taking off.”

Before 2009, when President Obama poured $90 billion into clean energy through his stimulus bill, the U.S. had no EV or solar industry to speak of. It now has nearly 250,000 EVs and nearly 500,000 solar rooftops, and both industries are still growing exponentially; Tesla and Solar City, both Elon Musk ventures, have both enjoyed soaring stock prices since going public. EV battery prices are not yet truly competitive with gasoline, although they’ve dropped 50% in five years, but retail solar prices, which have plunged 80%, are now competitive with fossil fuels in half the country. And the more they’re deployed, the cheaper they’ll get.

EVs are still less than 1% of the U.S. auto fleet, and solar still provides less than 1% of U.S. electricity. In terms of reducing emissions, they are still less significant than hybrid vehicles or wind power or energy-efficient appliances. But they are what the Silicon Valley types like to call “disruptive.” When you put a solar panel on your roof, your home becomes a mini-power plant. When you buy an electric vehicle, you suddenly control an automobile-shaped energy-storage device. It won’t be long before homeowners with both can be mini-utilities, buying power from the grid when it’s cheap and selling power to the grid when it’s expensive. Willett Kempton, a University of Delaware professor, has created electric vehicles that communicate and interact with the grid in real time; they earn about $150 per car per month by storing excess power when the grid gets temporarily overloaded.

That would make the economics of EVs more attractive, accelerating the route to mass adoption. “Net metering” will be similarly important for solar, allowing homeowners to sell power to the grid at attractive prices; as the Opower study demonstrated, time-of-use pricing can also help shape electricity demand. All of this will help create a more flexible, less centralized energy system, incorporating more renewable power without sacrificing reliability when the sun isn’t shining or the wind isn’t blowing, adapting instantaneously to changes in demand and supply with the help of modern information technology and Opower-style Big Data. Our cars (as well as other smart appliances) will optimize their power needs with our utilities, and we can intervene at any time over our iPhones.

You could imagine a future where solar panels and EVs (perhaps with additional backup storage, like the wall-mounted batteries Solar City and Tesla recently launched) help Americans declare independence from the grid, the way mobile phones have set us free from landlines. More likely, though, the clean-energy revolution will just change our relationship to the grid. Our utilities will be as dependent on us as we are dependent on them. And we’ll have power over our power.

Your browser, Internet Explorer 8 or below, is out of date. It has known security flaws and may not display all features of this and other websites.

Learn how to update your browser