Surplus Solar

California’s overabundance is a good thing.

De Blog Generic

At 1:00 on the afternoon of May 27, solar power plant operators in California curtailed 4,700 megawatts of energy production, nearly 40% of the state’s solar capacityIn that moment, California simultaneously set two renewable energy records: the most solar power ever carried by the distribution grid, and the most solar power ever taken off due to an overabundance. 

What may seem like a waste of electrons actually makes fiscal sense, according to industry experts cited in the LA Times. In fact, a number of recent studies have pointed to the fact that solar has reached such inexpensive levels that it’s cheaper to overbuild solar farms and curtail power production than install large-scale energy storage.  

In their study of renewable power production and curtailment scenarios in Minnesota, researchers Karl Rábago and Richard Perez found that “proactive curtailment associated with PV oversupply, is critical to achieving intermittency mitigation and delivering firm PV generation at the lowest cost.” The researchers call this “supply shaping through curtailment.” And scenarios modeled by the California Public Utilities Commission have found similar results, confirming that overbuilding solar facilities and curtailing power when necessary makes economic sense. 

As many of you are likely aware, in order to ensure that there is always enough energy to meet demandutility regulators have always included extra generation capacity in power plant planning. Overbuilding solar facilities follows similar logicexcept that it provides a non-carbon-producing reserve margin. 

But how much solar is too much? Industry experts agree that eventually states like California will need to invest in large-scale energy storage projects, develop rate structures conducive to demand management, and find mutually beneficial ways of sharing surplus energy with neighboring states. 

What are your thoughts on energy “supply shaping through curtailment” and California’s surplus of solar power? 

More in Renewables