The period occured in 2024 between late winter and early summer. “Compared to the same period in 2023, solar output in California is up 31%, wind power is up 8%, and batteries are up a staggering 105%.”
Link to the study PDF mentioned in the article: https://web.stanford.edu/group/efmh/jacobson/Articles/Others/25-CaliforniaWWS.pdf
One of the paper’s cowriters is Mark Z. Jacobson, professor of civil and environmental engineering and director of the atmosphere/energy program at Stanford University.
I just checked, and California’s electricity is roughly double the US average. And in fact, it is about 8X the price that I pay in Quebec.
Why is Quebec so cheap? Maybe it’s because the electricity generation system was converted from private to public in 1962. They paid off the loans used to purchase the system in under 3 years, and since then it has contributed to provincial finances. Of course, having mainly hydropower doesn’t hurt either.