I wrote that natural gas supplies about 42 percent of California’s electricity grid, the largest single source, and used that number to explain why every phone charge and cloud backup traces back to a gas plant somewhere. I need to correct that figure. It’s not just slightly off. The California grid has changed dramatically in the very recent past, fast enough that a number from even a year or two ago is already stale.
The most recent full year data, from the California Energy Commission’s 2025 generation figures, puts natural gas at about 35 percent of in-state generation, already below the 42 percent figure I used. But the more striking shift is happening month by month in 2026. According to the U.S. Energy Information Administration, utility scale solar generation in the CAISO grid actually surpassed natural gas generation on 82 percent of days during the first five months of 2026, up from just 21 percent of days in the same period the year before. Natural gas generation fell 60 percent year over year in that same window.
A GridLab analysis comparing two similar June days, one in 2025 and one in 2026, found gas fired generation dropped from 18 percent of California’s daily electricity output to just 5 percent, while renewable generation rose from 54 percent to 65 percent over that single year. A separate energy analysis group, IEEFA, found that as of mid-2026, there had been 68 days already that year when gas’s market share fell below 20 percent, and not a single day all year when gas accounted for more than half of CAISO generation, a sharp break from 2021, when gas never dropped below a 20 percent share and frequently exceeded 40 percent.
The main driver behind the shift isn’t just more solar panels, though California has added real solar capacity too. It’s storage. CAISO’s installed battery capacity grew from essentially nothing in 2021 to more than 16,000 megawatts by April 2026, letting the grid bank cheap midday solar and release it during the evening hours when demand peaks and the sun has already set, the exact window natural gas plants used to dominate.
None of this erases the point I was originally making about hidden energy costs, data centers, food systems, the electricity behind an ordinary day. It changes which specific fuel is doing the work behind that phone charge, and how fast that answer is currently shifting under my feet. A statistic about California’s grid that felt current when I wrote it was already meaningfully out of date by the time I checked it a few weeks later.
I’m updating the number. I’m also making a note to stop treating any grid statistic as a fixed fact rather than a snapshot of a system that’s currently changing month to month.
Sources. California Energy Commission (2025 generation data); U.S. Energy Information Administration; GridLab analysis; IEEFA.