When to Charge Electric Car?

With the increasing presence of electric vehicles (EVs) on the roads across the nation, a multitude of Americans are delving into the nuances of car charging. This encompasses everything from setting up home chargers to locating public charging stations and alleviating the infamous “range anxiety.”

However, amidst the surge in EV ownership and the plugging in of cars, a significant concern arises—potential strain on the electricity grid if the majority of drivers persist in nightly EV charging.

A recent study conducted by Stanford University sheds light on this predicament. If EV sales experience rapid growth over the next decade and most drivers maintain their nightly home charging routine, it could place considerable pressure on the electricity grid in the Western United States. This surge in demand during peak periods might elevate net electricity demand by approximately 25%. Such a scenario could prove troublesome in regions grappling with electricity demand surge during heatwaves and increased consumption.

Understanding EV Charging Dynamics

Charging an EV is markedly different from filling a conventional car with gasoline. EV charging is a gradual process. While certain chargers can replenish 80% of an EV battery’s capacity in 20 to 30 minutes, most charging instances are longer, spanning from two to 22 hours to achieve a full charge. Consequently, around 80% of EV charging typically transpires at home overnight when the vehicle is unused.

However, this charging pattern doesn’t align seamlessly with the evolving electricity generation landscape. The pinnacle of electricity demand surfaces during evenings, typically between 5 and 9 p.m., as individuals return home, engage lighting, watch television, and consume power. Conversely, solar panels generate energy primarily during midday hours. This juxtaposition results in peak electricity demand coinciding with a dwindling solar output.

Potential Grid Strain and Solutions

The Stanford study simulated charging behaviors of residents in 11 Western states and explored their impact on an electricity grid transitioning toward renewable energy sources. Ram Rajagopal, one of the study’s authors and a civil and environmental engineering professor at Stanford, remarked that the surge in EV adoption could substantially influence grid dynamics when approximately 30 to 40% of cars are EVs. Even if drivers schedule charging after peak hours, they’d be utilizing electricity during periods when renewable energy generation wanes. This could lead to increased carbon emissions and augmented demand for storage solutions.

To mitigate this challenge, researchers propose a shift toward daytime charging. Encouraging EV owners to charge at workplaces or public charging stations during late mornings and early afternoons, when surplus solar energy is available, can alleviate pressure on the electricity grid and diminish storage requisites. Transitioning from predominantly home charging to a blend of home and work charging could nearly halve the grid’s storage needs, particularly when 50% of vehicles are electric.

Another strategy involves restructuring electricity pricing to incentivize daytime charging. By offering cost-effective rates during peak solar periods, EV owners could be prompted to charge when solar energy generation is optimal.

Siobhan Powell, lead author of the study and a postdoctoral researcher at ETH Zürich, advocates for proactive expansion of public and workplace charging infrastructure. While she acknowledges the importance of home charging, she emphasizes the convenience of charging options at work or in public settings.

In conclusion, while existing EV owners need not drastically alter their charging habits, policymakers and stakeholders must anticipate the evolving landscape and strategically deploy chargers where daytime EV charging is viable. As clean energy integration advances, many of these challenges will be mitigated, ensuring a smoother journey towards widespread EV adoption.