In-brief analysis
November 24, 2025
Data source: U.S. Energy Information Administration, Electric Power Monthly
Note: Coal represents less than 1% each year.
Although natural gas generation still provides more electricity than any other source in California, electricity generation from natural gas has decreased over the past several years while generation from solar has increased.
According to data from our Electric Power Monthly, electricity generation from January through August 2025 (the latest data in our October release) was 140.9 billion kilowatthours (BkWh), 8% more than the same period in 2020.
The generation growth in recent years has been driven by solar. Solar generation by utility-scale power plants in California totaled 40.3 BkWh in the first eight months of 2025, nearly double the 22.0 BkWh over the same period in 2020. In the first eight months of 2025, solar generation increased 17%, or 5.9 BkWh, compared with the same time period in 2024.
Between January and August 2025, natural gas supplied 45.5 BkWh of electricity, 18% less than during the same period in 2020. Output increased in 2021 due to drought-spurred reduced hydroelectric output, but natural gas generation has fallen since then. The largest year-over-year drop occurred this year, when natural gas generation declined 9.5 BkWh, or 17%, compared with 2024.
In low-water years, the need for natural gas generation can increase. For example, hydro output fell in the first eight months of 2021 to 10.3 BkWh, and natural gas generation spiked to 63.5 BkWh.
Natural gas generation decreases during the middle of the day when solar generation is highest. During the midday hours (between noon and 5:00 p.m.) in May and June, which have similar cooling requirements, solar generation increased from 10.2 gigawatts (GW) in 2020 to 18.8 GW in 2025, according to the California Independent System Operator (CAISO). CAISO changed its data collection methodology for natural gas in December 2023, and data posted prior to that are not comparable.
Data source: U.S. Energy Information Administration, Hourly Electric Grid Monitor, and California Independent System Operator (CAISO)
Note: We did not include natural gas data for 2020 or 2022 because CAISO changed its data collection methodology for natural gas in December 2023 and data earlier than that are not comparable with data collected after that date.
During peak evening hours between 5:00 p.m. and 9:00 p.m., generation from batteries charged by excess solar generation during midday rose from an average of less than 1 GW in May and June 2022 to 4.9 GW in 2025, displacing natural gas generation during that period. In 2025, the hourly data show a decrease in natural gas generation during the midday hours, when solar generation is at its peak.
Principal contributor: Andrew Iraola
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