Solar curtailment in California on the rise, EIA says

Share on facebook
Share on twitter
Share on linkedin
Share on reddit
Share on email
California’s ISO plans to add an additional 1.6GW of utility-scale solar and 400MW of onshore wind capacity this year. Image: Sempra Energy.

Renewable capacity additions in California mean the curtailment of solar generation in the state is increasing, according to the US Energy Information Administration (EIA).

The California Independent System Operator (CAISO) region, the part of the grid that covers most of the state, curtailed 1.5 million MWh of utility-scale solar last year, or 5% of its total utility-scale solar production, the EIA said. In 2020, solar curtailments accounted for 94% of the total energy curtailed in CAISO.

Curtailment tends to be higher during spring when solar output is high and electricity demand drops due to moderate temperatures decreasing demand for heating and air conditioning. For example, in the early afternoon hours of March 2021, CAISO curtailed an average of 15% of its utility-scale PV output.

The EIA said spikes in solar curtailments have followed an increase in new renewables additions. California continued to be the leading US state for solar deployment last year, installing an additional 3.9GW, according to the Solar Energy Industries Association (SEIA) and analysts Wood Mackenzie.

Meanwhile, PV systems sited at households or businesses are further decreasing the need for CAISO-operated generation, leading to more solar curtailments. This could be further impacted by proposed rules that would require new commercial buildings in the state be equipped with solar and battery storage.

To help meet California’s target of 50% renewables generation by 2025, CAISO plans to add an additional 1.6GW of utility-scale solar and 400MW of onshore wind capacity this year, according to the EIA.

Among the solutions that CAISO is exploring to limit curtailment is an increase in deployment of battery storage systems, which can be charged at times when excess solar generation may be curtailed. This year, CAISO is expecting to add 2.5GW of battery storage capacity.

The EIA said hydrogen-based energy storage could also help reduce solar curtailments, with surplus renewable electricity stored for later use.

Another option is CAISO’s Energy Imbalance Market, a real-time market that allows participants outside of the system operator’s region to buy and sell energy to balance demand and supply. In 2020, 16% of total possible curtailments were avoided by trade within the EIM.

Among the other solutions considered by CAISO is increasing demand response, which would adjust consumer demand when warranted, and encouraging time-of-use rates to better match consumer prices with real-time energy prices.

The curtailment insight from EIA follows the recent publication of research that suggests falling solar wholesale prices in California mean subsidies could be needed to sustain the cost-effective deployment of PV in the next 30 years. The report from research centre the Breakthrough Institute found that falling daytime prices reduce the incentive for installing additional solar, while increased daytime curtailment reduces the benefits of currently installed solar generation.

Read Next

May 18, 2022
Powering electrolysers with renewables generation that would otherwise be curtailed could be an effective strategy for producing green hydrogen in the coming years until the H2 sector benefits from further cost declines, it was suggested during a panel discussion.
May 16, 2022
Japanese energy firm Osaka Gas is to enter the US utility-scale solar market through a joint venture with project developer Oriden.
May 16, 2022
Solar PV manufacturer Maxeon Solar Technologies is to begin selling home energy storage products after partnering with battery producer AlphaESS.
May 13, 2022
Investment management firm Axium Infrastructure has acquired Boston-based solar and energy storage developer BlueWave, its first acquisition of a renewables developer.
May 13, 2022
Welcome back to PV Tech's live coverage of the third and final day of Intersolar Europe 2022. This story will be updated throughout the day, so be sure to refresh for the latest news, product launches and insight from the exhibition
May 12, 2022
Energy investment platform CleanCapital has secured a US$200 million credit facility to support its pipeline of distributed solar and energy storage projects.

Subscribe to Newsletter

Upcoming Events

Solar Media Events
June 14, 2022
Napa, USA
Solar Media Events
October 4, 2022
New York, USA