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

A Different Solar Milestone: 1.5 Gigawatts of Rooftop in California

A solar roof in San Francisco | Photo: KQED Quest/Flickr/Creative Commons License

We've posted a lot here in recent weeks about one California solar record after another being broken, but those numbers don't tell the whole story. The California Independent System Operator (CaISO), whose figures we rely on in reporting those records, tracks only solar energy that's fed into the grid from commercial facilities. If you have solar on your rooftop and run your electric meter backward as you feed solar into the grid, your contribution isn't counted.

On Thursday, the group Environment California announced another solar milestone that helps flesh out the fuller picture of California solar: at least 1,500 megawatts of rooftop solar has now been installed in the state.

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"Today's solar milestone is a testament to California's commitment to a brighter, cleaner future," said Environment California's Michelle Kinman in a press release. "Homes, schools, and businesses throughout the state are reducing air pollution, fighting global warming, improving the reliability of our electricity grid, boosting the economy, and creating local jobs, all by going solar."

In the accounting method which CaISO uses to track power coming into the grid, most small rooftop solar arrays aren't counted as generation. Instead, seeing as they're behind electric meters, they're considered a reduction of demand. Generate 1,000 kilowatt-hours of solar power on your roof or conserve that same amount by turning off your air conditioning, and it's all the same to CaISO's stats.

That's not necessarily CaISO's fault: it's more an artifact of the way the grid is built at the moment. But counting rooftop solar behind the meter as demand reduction rather than generation means that that rooftop solar doesn't count toward California's Renewable Portfolio Standard goals, which oblige utilities to derive a third of their power from renewable sources by 2020.

That's one reason many solar activists advocate a system of Feed-in Tariffs (FiTs) instead: with FiTs, property owners sell power directly to utilities without involving their electric meter. Rather than just running their meters back to zero and then giving free power to the grid, solar panel owners get paid for every bit of power they produce. It's an incentive to install more solar capacity on your roof -- what point is there to spend a few extra thousand dollars to give power to the utility for free? -- and it also gets that generating capacity out from behind an electric meter where it can be counted properly.

Regardless of how it's accounted for, getting more rooftop solar installed in California is a good thing, and Environment California credits the Million Solar Roofs initiative of the state's Go Solar campaign with making the 1,500 megawatt benchmark possible. The campaign's goal is to get 3,000 megawatts of rooftop solar installed by the end of 2016. The state reached 1,000 megawatts of rooftop solar in November 2011. Do the math: reaching 1,500 megawatts this month means the state installed 500 megawatts in 15 months. We have another 1,500 megawatts to install by end-2016 to make the Go Solar campaign's goal. If we keep installing at the same rate, we reach 3,000 megawatts with two weeks to spare.

Of course if we started installing solar at the rate at which Germany is doing so, we'd get there before July 4.


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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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Nice reporting on CAISO and rooftop solar records. Plus, there are now likely over two hundred MW of California solar projects that are neither CAISO transmission interconnected, nor rooftop. Examples include distribution-level interconnected plants (both Feed In Tariff and utility-owned generation), and publicly owned utility (eg SMUD, LADWP) interconnected plants at both the distribution and transmission levels.