Temperatures in early September were close to 45 °C in California, but the electrical network resisted, without vast power cuts, unlike in 2020. A performance due in part to the exponential installation of giant batteries capable of storing solar energy.

At the Long Beach headquarters, occupied by rows of thousands of batteries resembling a computer server farm, electricity provider AES’s director of operations, Weikko Wirta, saw his 400 MW facility, one of the largest in the state, run at full capacity during the heat wave.

“The batteries stepped in and … played a critical role” during the latest heat wave, says the chief operating officer of power provider AES, which has been in charge of the new plant since 2021.

As a result, the company was able to store solar energy produced during the day and redistribute it in the evening to “fill the gap between 4-5 pm and 10 pm”, when the drop in photovoltaic supply at sunset and record demand for air conditioning threatened to cause a collapse of the power grid.

In the summer of 2020, a brutal heat wave affecting the entire Western United States forced California, a pioneer in renewable energy, to cut power to 800,000 homes and businesses for two days. This was the first time in almost 20 years.

The summer of 2022 has seen extreme temperatures this year; such voluntary blackouts were narrowly avoided in early September, thanks partly to the race to meet California’s climate goals.

California is aiming for 100% carbon-neutral energy production by 2045. Between 2020 and 2022, it has increased its battery energy storage capacity tenfold, according to its energy commission.

During Labor Day weekend, at the peak of the heat wave, the batteries produced 3,300 megawatts in the evening, according to power grid regulator California ISO.

“That’s more than the Diablo Canyon nuclear plant, which is the largest power plant in the state and produces about 2,200 megawatts,” analyzes Mike Ferry, a University of San Diego researcher.