California last week enshrined its 2035 ban on sales of new gasoline vehicles that don’t plug in. And now this week it’s telling the relatively few EV drivers in the state to hold off on plugging in during the afternoons.

On Thursday afternoon, leading into the Labor Day long weekend, the state’s Independent System Operator (ISO) sent out a Flex Alert notice, indicating it called for a day of “voluntary electric conservation” on Friday—the third consecutive day this week, and a day that many EV drivers had expected to use a full charge on the way out for the long weekend.

The Flex Alert conservation actions suggest that Californians charge electric vehicles before 4 p.m. That’s a situation only feasible for those who work at home, for instance, or those who have workplace charging.

2022 Tesla lineup (Courtesy of Tesla, Inc.)2022 Tesla lineup (Courtesy of Tesla, Inc.)

EV sales have skyrocketed in California, and it cracked 15% EV sales by the end the second quarter of 2022, buoyed by Tesla registrations. But gasoline vehicles will remain in use for decades and the fleet turns over slowly. According to data from the Department of Energy and Experian, updated in June 2022, California leads the nation in current EV registrations, with about 563,000 EVs in its fleet. California has about 30 million registered vehicles, so even in the Golden State less than 2% of vehicles are fully electric.

There was no particular outage or technical reason for the alert, the California operator explained—simply that it’s hot, and electricity demand is up due to air conditioning use.

In broader guidance, the operator suggested that during the period Thursday, from 4-9 p.m., consumers are urged to set their thermostats to 78 degrees or higher, minimize appliance use, and turn off unnecessary lights. Sunset Thursday in Los Angeles was at 7:19 p.m.

“They should also avoid charging electric vehicles while the Flex Alert is in effect,” it summed, introducing the idea of outages. “Reducing energy use during a Flex Alert can help stabilize the power grid during tight supply conditions and prevent further emergency measures, including rotating power outages.”

Audi e-tron, on the Golden Gate BridgeAudi e-tron, on the Golden Gate Bridge

The optics aren’t so great. If California wants to ramp up the number of EVs in its fleet, how will the grid handle next year’s heat waves?

Smart charging is part of that answer, and many utilities offer Time of Use rates that help incentivize EV owners to charge at a time of the day advantageous to the grid and a greater use of renewables. But as California accelerates its shift to EVs it will take more than that. A 2020 report suggested that the state’s energy demand could rise about 25% overall, requiring massive grid upgrades, if all of its passenger vehicles were fully electric.

This isn’t the first time the ISO has issued these requests. For instance, it issued several Flex Alerts during a June 2021 heat wave.

EVgo curbside DC fast chargers at Southside Park, Sacramento, California [CREDIT: EVgo]EVgo curbside DC fast chargers at Southside Park, Sacramento, California [CREDIT: EVgo]

In June this year, the Energy Information Administration (EIA) suggested that a sustained California drought would increase the carbon footprint of the state’s electricity used to charge EVs—because a cut in California’s hydropower generating capacity will nudge in more carbon-intensive sources for a greater amount of the mix. The state’s grid has shown some progress this year, however; in April it was briefly powered entirely by renewable energy.

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