Solar Glut: Half of California's Solar Power Sometimes Goes to Waste, Research Shows

Some days more than half of California's available solar power goes to waste, according to research from the California Institute for Energy and Environment. "In the last 12 months, California's solar farms have curtailed production of more than 3 million megawatt hours of solar energy," according to a data analysis by the Los Angeles Times — enough to power 518,000 California homes for a year.

And it was curtailed "either on the orders of the state's grid operator or because prices had plummeted because of the glut. The waste would have been even larger if California had not paid utilities in other states to take the excess solar energy, documents from the state's grid operator show."

That means green energy paid for by California electricity customers is sent away, lowering bills for residents of other states. Arizona's largest public utility reaped $69 million in savings last year by buying from the market California created to get rid of its excess solar power. The utility returned that money to its customers as a credit on their bills. Also reaping profits are electricity traders, including banks and hedge funds. The increasing oversupply of solar power has created a situation where energy traders can buy the excess at prices so low they become negative, said energy consultant Gary Ackerman, the former executive director of the Western Power Trading Forum. That means the solar plant is paying the traders to take it. "This is all being underwritten by California ratepayers," Ackerman said...

The solar glut also means higher electricity bills for Californians, since they are effectively paying to generate the power but not using it. California's electric rates are roughly twice the nation's average, with only Hawaii having higher rates. Rates at Southern California Edison and Pacific Gas & Electric increased by 51% over the last three years. "Ratepayers aren't getting the energy they've paid for," said Ron Miller, an energy industry consultant in Denver. He calculates that the retail value of the solar energy thrown away in a year would be more than $1 billion.

Gov. Gavin Newsom's advisors and those who manage the state's electric grid say they are working to reduce the curtailments, including by building more industrial-scale battery storage facilities that soak up the excess solar power during the day and then release it at night. Officials in the governor's office declined to be interviewed, but issued a statement saying the curtailments are often because of congestion on transmission lines, rather than a statewide oversupply of power. The state has been spending heavily to upgrade transmission lines to ease the congestion. "It's also important to have extra energy resources available that can help the state during periods of extreme weather and historic heatwaves when demand is particularly high, which have happened the past few years," the statement said...


The commercial solar industry contends that the expansion of storage capacity to bank solar power will eventually eliminate the glut.

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