(Bloomberg) -- California just mandated that nearly all new homes have solar, starting in less than two years. Now, it’s going to have to figure out what to do with all of that extra energy.
Already, the state is flooded with so much solar power during the day that it has to turn off some of its sun-fueled plants at times and often needs to ship excess green energy to neighboring states. The phenomenon has produced what state grid operators have been calling the duck curve -- that’s when net power demand craters during daylight hours and then ramps up after sunset and natural-gas generators fire up to meet customer demand.
It’s an unintended consequence of the Golden State’s effort to slash greenhouse gas emissions and get half of its electricity from renewable sources by 2030, and has vexed the state’s grid operators. California’s top utility regulator warned last week of a looming energy crisis if the region doesn’t start planning for a future with more people either generating their own power or getting it from suppliers besides the big utilities.
“As the amount of renewables on the system grows, grid operators need increased visibility into behind-the-meter resources,” said Steven Greenlee, a spokesman for California Independent System Operator Corp., which runs the state’s power grid. Grid operators will need more visibility into how these home systems are working, he said.
To put it another way, “it has the potential to make the duck curve duckier,” said Ethan Zindler, a Washington-based analyst for Bloomberg New Energy Finance.
The solar industry and environmental groups praised the new rules passed by the California Energy Commission Wednesday, saying that requiring rooftop solar on homes starting in 2020 will lead to more efficient homes, cut emissions and save people money over time.
The provisions allow for energy storage systems to be paired with solar arrays, though they’re not required. That creates the potential to store electricity during the day and use it later in the evening, easing the problem.
The glut of solar during the day “is a temporary problem that will be solved with the addition of storage and more sophisticated demand-response programs” to balance intermittent supplies from wind and solar farms with peak demand periods, said Bernadette Del Chiaro, executive director of the California Solar & Storage Association.
“Today’s decision incorporates storage along with the solar to head off this issue at the pass,” she said. “You should really think of this mandate as solar on the roof, battery in the garage.”
The new requirements could lead to a rise in demand for batteries to be installed with solar systems, said Lynn Jurich, chief executive officer of Sunrun Inc., the largest U.S. residential solar installer.
The additional solar homes stand to add as much as 260 megawatts of annual solar power in the state -- about the size of one large solar farm.
“When greenhouse gases are really being emitted by California’s power sector is after the sun goes down -- but this mandate will do little to help,” said Colleen Regan, an analyst for Bloomberg New Energy Finance. “Other large-scale renewable technologies, as well as energy efficiency, would be better placed to help reduce power-sector emissions than distributed solar at this point.”
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