Forty-eight days into 2025, CAISO gas use for electricity is down almost 28%, while battery use is up 78%, and solar has already met 100% of demand in the midst of winter.
California has kicked off 2025 with impressive clean electricity generation, marked by a decline in gas use, increased wind and battery output, and—last Sunday—solar meeting nearly 100% of grid demand in the middle of winter.
Mark Jacobson, a Stanford professor of civil and environmental engineering, has been diligently tracking electricity generation trends from wind, water, and solar (WWS) over the past year. His research aligns with a significant uptick in periods when 100% of the state’s grid demand is being met by clean energy. This increase is largely due to rapid storage expansion, which has started to take over portions of the evening demand peak from gas, reducing solar curtailment and improving grid stability.
Now, as the new year unfolds, the pace is picking up.
California recorded four consecutive days from February 14 to 17 when WWS generation exceeded 100% of grid demand at times. This occurred about a week and a half past the midpoint of winter, when solar output is typically lower due to shorter days and a lower sun angle. On Sunday afternoon, as noted in the chart above, solar power still managed to peak at nearly 100% of electricity demand in the middle of the day.
The chart below illustrates how, over the first 48 days of 2025, total WWS supply has exceeded fossil gas generation. Jacobson reports that, so far this year:
- WWS electricity output is up 18% year-over-year and 32% higher than gas
- Gas usage has declined by almost 28%
- Solar electricity generation has surged 33.8%
- Battery output has increased by 78%
Jacobson’s data also show that, on average, 1.6 hours per day are fully powered by WWS.
Over the past year, California’s rapid expansion of battery storage, along with continued growth in solar, wind, and hydro, has driven an unprecedented number of days when renewables met the state’s electricity demand. A key factor in this shift is the increasing role of energy storage in replacing gas during evening demand peaks, enabling greater grid reliability and allowing solar to peak at 123% of total demand. Just three years ago, on May 2, 2022, California briefly reached 101% renewable electricity for the first time—a milestone that once seemed fleeting but is now becoming routine.
Battery storage is also credited with improving grid stability. In 2019, state officials warned that an acceleration of stable capacity deployment was necessary to avoid grid instability during evening periods in September. While summer grid challenges did materialize in subsequent years, the massive expansion of battery storage by 2024 has significantly reduced the frequency of grid outages.
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