Charging your EV at night is about to become more expensive

Overnight charging has always been a perk of EV ownership, but what happens when it becomes too expensive to power up in your driveway at night?

One of the perks of electric vehicle ownership is charging your car overnight while parked in your driveway at home. Electricity demand is usually low, so rates are fairly cheap, making it both convenient and affordable for many people. But that’s about to change as more people buy EVs and the demand for overnight charging begins to rise, according to a new study published today.

The study, which was conducted by a team at Stanford University and published in Nature Energy, found that increasing EV ownership in the western US could lead to peak net electricity demand increases by up to 25 percent by 2035, the year California has said it would ban the sale of gas-powered cars and trucks.

That demand could rise to as much as 50 percent under a “stress test” scenario where every vehicle on the road is a plug-in model, the team concludes. More demand translates into higher prices, which means the glory days of cheap overnight charging may be coming to an end.

To better prepare for a future with more EVs, the study’s authors recommend vehicle owners do more daytime charging, either at work or at public charging stations. This becomes especially important as more renewable sources of power generation come online, including solar and wind power.

“In the future grid with higher renewable generation, timing is more important and net demand tells a very different story than total demand,” the study reads. “Shifting drivers from home to daytime charging improves all metrics of grid impact including ramping, use of non-fossil fuel generation, storage requirements, and emissions. This insight is robust across varying levels of EV adoption.”

To be sure, this is not just a California problem, even though the state has the highest number of registered EVs on the road today — around 1 million plug-in models, or about 6 percent of total vehicles.

“All states may need to rethink electricity pricing structures as their EV charging needs increase and their grid changes,” said Siobhan Powell, lead author of the study, in an email.

Getting more drivers in the US to switch to plug-in power is seen as crucial in reducing pollution, reducing carbon emissions, and fighting climate change. But many challenges lie ahead. EVs are more expensive than gas-powered models and, for now, harder to find. The charging infrastructure in the US is unreliable and seen as a barrier to broader adoption of EVs. And the materials that are needed for lithium-ion batteries are in high demand, leading to supply chain problems.

The Biden administration has identified charging as a unique challenge, funneling billions of dollars into projects across the country to install more chargers, including DC fast chargers that can charge an EV in much less time than typical Level 2 chargers. Much less focus has been put on proper grid management, which will become more of an issue as EV sales continue to go up.

Demand charges from utility companies, for example, tend to dominate charging companies’ operating costs, further complicating the business case for building more charging stations. The total cost of electricity is higher based on the level of charging they provide. These calculations need to be rethought if the government wants to incentivize the EV charging industry.