California Battery Storage Cuts Solar Curtailment By 12%, Absorbs 39GWh Daily

In the first five months of 2025, the solar power curtailment rate in the CAISO grid was 11.5%, a year-on-year decrease of 12%, and the absolute value increased by 4.1% due to the growth in power generation. The peak curtailment in March reached 58,000MWh, and the battery system consumed 38,897MWh on that day (mainly from solar power). Data analysis indicates that if there is no energy storage configuration, the California curtailment rate will increase by 67%.

 

The scale of energy storage in California is continuously expanding. Since 2024, the region has added 77 systems with a total capacity of 4.79 GW/16.39 GWh, with an average duration of 3.4 hours. As of April 2025, grid-connected energy storage reached 15.7 GW, and the theoretical storage capacity exceeded 45 GWh. The design strategy for solar systems has shifted to over-provisioning. First Solar estimates that over-provisioned projects can increase revenue by providing frequency modulation and other auxiliary services. Comparative studies show that in highly power-restricted areas (such as Minnesota), over-provisioning of solar systems is more economically viable than seasonal energy storage.