News and analysis about energy in California with an eye toward renewables.

California Sets 'Record' For Winter Solar Power Generation

Renewable energy output for December 19,2012 in California | Image via CaISO

In August ReWire touted the state's passing of the gigawatt solar production record, where the state's grid operators reported a record 1,029 megawatts of solar electricity entering the grid. And now we can report a record slightly more subtle but every bit as important: the state got pretty close to that record-setting August mark on the week of the Winter Solstice, the least-sunny time of year.

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On Wednesday, December 19, the CaISO's preliminary figures for renewable energy output, which are displayed in the chart at the top of this post, indicated that for Wednesday's solar output reached a peak somewhere between 950 and 1,000 megawatts at around 10:30 a.m., and held there until just after 1:00 p.m.

In terms of actual power delivered, that's not a huge amount. What makes Wednesday's figures notable is that they happened the week of the Winter Solstice, when the sun is lower in the sky than at any other time of the year. The sun being lower in the sky means less solar energy hitting California, meaning less output from solar panels. At the latitude of Los Angeles, sunshine hitting solar panels on the winter solstice can deliver something like half the energy it does during summer, and less sunlight hitting solar panels means less electrical power generated. And the seasonal drop-off is even starker north of Los Angeles.

Which means that California's solar power generating capacity is growing by leaps and bounds even since that August record. Compare that near-gigawatt of winter solar with the figures from this time last year: We had a maximum of 200 megawatts or so of solar output in December 2011.

That record winter output is pretty much all photovoltaic power, by the way. CaISO has recently started listing PV and solar thermal's contributions to the grid separately, and solar thermal's contribution is about a hundredth that of PV at the moment.

The upshot is that 2013 is bound to be a year in which California's solar capacity sets one record after another. Good news.

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About the Author

Chris Clarke is a natural history writer and environmental journalist currently at work on a book about the Joshua tree. He lives in Joshua Tree.
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