| Work Detail |
Curtailment—the intentional reduction of energy production—continues to increase for both solar and wind power in the state. Grid operators are tasked with balancing electricity supply and demand to ensure a stable and secure electrical system. When power generation significantly exceeds demand, operators must intentionally reduce production in a process called shed. In California, solar power curtailment has been on the rise for years, reaching new highs in 2024, according to the Energy Information Administration (EIA). The EIA indicated that solar energy accounts for 93% of all electricity discharged in the California Independent System Operator (CAISO) region, which serves most of the state. In 2024, CAISO curtailed 3.4 million MWh of utility-scale wind and solar production, a 29% increase over the amount of electricity curtailed in 2023. Discharge is typically dictated by grid price signals, according to the EIA. More rarely, grid operators issue orders to halt production during periods of grid congestion or excess energy. CAISO also mandates solar generation to make room for natural gas generation. A certain amount of natural gas generation must remain online throughout the day to meet North American Electric Reliability Corporation (NERC) reliability standards and to have generation available in time to ramp up production in the evening hours. CAISO is trying to reduce cuts by: Negotiation with neighboring balancing authorities to try to sell excess solar and wind energy Incorporating battery storage into ancillary services, energy markets and capacity Inclusion of discharge reduction in transmission planning In addition, companies are finding other ways to utilize excess renewable energy production, such as using it to produce hydrogen, some of which will be stored and blended with natural gas to support peak demand events in the summer. CAISO is also reducing waste by incorporating flexible resources such as battery energy storage with dispatch durations of four to eight hours. The batteries can charge with excess solar energy at midday and then discharge that energy when the sun sets, providing electricity during peak hours. Solar power supplies approximately 50% of CAISOs demand during daylight hours, but solar production decreases when demand increases, as people return home from work in the evening and turn on air conditioning and appliances. Energy storage can help store and dispatch energy during these critical times to smooth out supply and demand peaks and reduce spillage. Energy storage is already ramping up to meet this challenge, as CAISO battery capacity grew 45% in 2024, from 8 GW in 2023 to 11.6 GW in 2024, according to the EIA. By 2014, a combined 9.7 GW of wind and solar PV capacity had been built in California. By the end of 2024, that figure had increased to 28.2 GW. As renewable capacity increases, grid operators will need to continue to find solutions to match electricity demand with energy production. |
