California’s ISO, which operates most of the state’s electrical system, projected that demand plus required reserves in case something goes wrong would exceed power sources for several days this week.
High temperatures are expected to be in the 90s Fahrenheit (approximately 33 degrees Celsius) in the Angels Wednesday through Saturday, which is more than 20 degrees Fahrenheit above the normal high for the time of year, according to AccuWeather.
The ISO projected that the largest deficit would occur on Thursday after the sun sets and solar power is no longer available.
A heat wave last August forced California utilities to impose rotating blackouts that left more than 400,000 customers without power for two and a half hours when supplies ran out.
The grid operator forecast peak demand to rise from 40,919 megawatts (MW) on Wednesday to 43,820 MW on Thursday. That compares to a historic peak of 50,270 MW in July 2006.
The ISO said Thursday’s peak plus reserves was more than 3,300 MW over supplies expected to be available at that time.
The ISO has said it expects to have around 50,734 MW of supply available this summer, but some of that comes from solar power.
In early June, the ISO, which does not count all solar power as available since it only works when the sun rises, said it had more than 14,100 MW of solar capacity that produced a record 13,205 MW in May.
Additionally, the ISO cautioned that it may not be able to rely on neighboring states for much more power because the California heat wave was covering much of the West as well.
ISO currently obtained 29% of its power, or more than 7,200 MW, from imports. That compares with a peak of 9,956 MW in May and a record 11,894 MW in September 2019.