Too many electric cars charging at night? Power grid may be overloaded

If most drivers continue to charge their vehicles mostly at home overnight, the increase in electric car ownership could put a pressure on the power systems.

By 2035, it's predicted that 50% of drivers would be using electric vehicles. This makes daytime charging alternatives essential to help the western US power grid meet  demand, according to a New Scientist report.

Power consumption models

This conclusion was reached using computer models to examine the impact that driver charging habits and the infrastructure for charging stations at home and in public may have on peak net electricity demand -- the highest electrical demand minus power from solar and wind sources.

When states reach 50% electric vehicle ownership, the peak net electricity demand could increase by 25% if drivers charge their cars mostly at home throughout the night.

“One of the big results from our study is that just making the shift of which charging infrastructure you build and where you encourage people to charge is a huge difference in the result for the grid,” New Scientist quoted Siobhan Powell as saying at the Swiss Federal Institute of Technology in Zurich, Switzerland. Powell led the research while at Stanford University in California.

Charging trends

In order to analyze charging trends from the actions of 27,700 electric vehicle drivers in the San Francisco Bay Area, Powell and her colleagues used computer simulation.

The models might anticipate the effects of an increased population of 48.6 million future electric vehicle owners on the western US power system, which supplies electricity to 11 states, including California.

According to Ram Rajagopal at Stanford University, the results also demonstrate how switching to daytime charging schedules could help the western US grid utilize its surplus solar electricity effectively.

Charging habits

Instead of forcing power grid operators to invest in greater energy storage to store daytime solar electricity for nighttime charging, daytime charging can use solar power when it is instantly accessible.

According to computer simulations, incentivising more drivers to charge during the day might cut the grid's energy storage needs by $700 million to $1.5 billion when compared to the status quo, when most drivers charge at home at night.

By 2035, 50% of personal vehicles becoming electric looks ambitious, according to Gil Tal from the University of California, Davis, who was not engaged in the study.

He said that as more people are working from home, some electric cars might be charged at home during the day, which could help to reduce some of the predicted spike in overnight charging demand.

However, he claims that overall the study's results are positive, indicating a future driven by renewable energy and transport.