California Solar Sets Record, But That’s Not The Big News

On Saturday, March 16, California set a new solar energy record. Just before 3 o’clock in the afternoon, solar output peaked at 10,765 megawatts, the highest amount ever, though just a smidgen more than the previous record set last June. According to the California Independent System Operator (CAISO), demand at that time, not including behind-the-meter solar, was around 18 gigawatts. Los Angeles and Sacramento are not part of the CAISO grid.

That meant solar was meeting 59% of the grid’s power needs at that moment.That’s wonderful news, but what should get solar proponents really excited is that CAISO was a net exporter of electricity to other systems at the time the record was set. As PV Magazine points out, CAISO is required by its existing contracts with out-of-state energy suppliers to import a certain amount of electricity even when it doesn’t need it.

When that happens, some of the locally generated electricity has to be exported, and in extreme cases, the generation is just shut off or dumped, a process known as curtailment in the industry. Since it is more difficult to decrease output on a moment-to-moment basis from traditional energy sources like hydro or gas-fired generating stations, the electricity curtailed most often comes from renewable energy facilities, especially solar.

Depending on market considerations at the time, sometimes CAISO actually has to pay other utility operators to take its excess electricity, particularly during the mid-afternoon when solar output is at its peak. But that didn’t happen in this instance. Growing battery storage capability in California is one of the reasons why.

The data from CAISO only tells part of the solar record story, however, since behind-the-meter solar — which is estimated to be half as much as grid-scale solar — is not included in those numbers. That means at that time on Saturday, March 16, total available solar energy within the CAISO system was closer to 16 gigawatts.

Based on data from the US Department of Energy, PV Magazine calculates that 14% of California’s annual demand for electricity was met from in-state solar resources last year and that number is expected to be far greater this year as California once again adds more solar generating capacity than any other state.

Opponents of solar and other renewables like to point out the cost of electricity in California has gone up steadily in the past decade, which they attribute entirely to the expense of building wind and solar generating facilities. What they ignore completely is the money utility customers have been forced to expend to keep unprofitable conventional generating facilities running and the burden that existing contracts impose on everyone.

They also totally exclude any intangible but very real health and environmental impacts from drilling for, transporting, and burning fossil fuels to make electricity. In today’s superheated political sphere, half-truths and outright lies are considered business as usual. Despite their distortions, renewable energy is rapidly displacing conventional generating plants, something that means we can all breathe a little bit easier.


California Solar Sets Record, But That’s Not The Big News, by Steve Hanley, PV Magazine, March 24, 2019.

1 reply
  1. Glen Casanova
    Glen Casanova says:


    Good article, and I agree with you that it’s great to see the continued growth of renewables in the California market.

    Some of the conclusions either in the article aren’t supported by the facts or they are misleading.

    You mention, “Sometimes CAISO actually has to pay other utility operators to take its excess electricity, particularly during the mid-afternoon when solar output is at its peak. But that didn’t happen in this instance.” Real time system prices “just before 3pm” may not have been negative but in the hours leading up to 3pm they were zero. CAISO may not have been paying other utilities to take the excess, but they were giving it away for free.

    You also lead the readers to believe there were no curtailments on the day the solar peaked. Granted, your article does say that at the “instant” the record was set the CAISO was a net exporter. However, the CAISO daily curtailment report shows that during the 3:00pm hour the maximum curtailment was 675 MW, a number that grew to 1,475 MW at 4pm. To put this in perspective, the 1,475 MW represents almost 14% of all solar power on the system.

    So while your statements might be factually correct that at the absolute “instant” the peak occurred the CAISO might have been a net exporter, the bigger picture is the price was $0 and over the course of that hour not only was the price paid for ALL power, including solar $0, there were 504 megawatt hours curtailed.


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