California’s electricity grid is expected to meet peak demand this summer, with state energy officials pointing to the massive growth in solar and battery storage resources as key.
A surplus of at least 5,500 MW is projected to be available to California during peak demand under normal conditions and 1,368 MW under extreme conditions, according to a May 1 reliability report by the California Energy Commission, the California Public Utilities Commission (CPUC) and the California Air Resources Board.
As of April, more than 12,000 MW of battery storage capacity is online and serving the grid, with almost all the capacity becoming available in the past four years, CPUC staff member Christina Pelliccio said at a May 2 joint agency reliability meeting. By 2028, another 15,000 MW of storage resources are expected to be available, accounting for the majority of the 20,000 MW of new resources expected in that time.
“CAISO will be able to rely on the large amounts of storage, solar and hybrid projects that are under development and projected to be online by August 2026,” CPUC Senior Analyst Behdad Kiani said at the meeting.
However, storage resources are the energy technology most affected by Trump administration tariff changes, BloombergNEF Senior Policy Associate Derrick Flakoll said. Assuming a 54% import tariff on China, battery storage additions in the U.S. in 2026 are expected to decrease from a forecasted 15 GW to about 10 GW. BloombergNEF projects the cost for a four-hour battery energy storage system will increase from about $200/kWh to about $260/kWh in 2026 due to the 54% import tariff.
Even so, battery storage project developers have not cited increased tariffs as an issue yet, said Rohimah Moly, deputy director of energy and climate at the California Governor’s Office of Business and Economic Development.
“But we have asked developers how the proposed tariffs will impact their projects,” Moly said. “A lot of the developers … are doing some behind the envelope calculations and will come back with us with some more information.”
Batteries and other power equipment also are expected to see supply chain issues, Branden Sudduth, vice president of reliability planning and performance analysis at WECC, said at the meeting. The costs and lead times of transformers and switchgears continue to increase, and more than half of balancing authorities in the WECC region have said they’re concerned about procurement delays for these pieces of critical equipment.
In the immediate future, between 2,100 MW and 5,800 MW of new resources will be coming online by September, the vast majority of which are battery storage and solar projects, the report says. Most battery storage energy will dispense between 7 p.m. and 8 p.m.
Although California is set to meet demand this summer under normal conditions, in a worst-case scenario, the state could need to tap into more than 2,600 MW of contingency resources, according to the report. For example, wildfires outside the state could reduce import capacity by as much as 4,000 MW, the report says.
“We have moderate to severe drought conditions this year,” Jeff Fuentes, assistant chief at the California Department of Forestry and Fire Protection, said at the meeting. “In the Pacific Northwest, we have abnormally dry conditions … we also have an early spring, which causes a longer growing season.”
In Southern California, several “pulses of moisture in February and March coupled with the recent rain this week is allowing green-up to continue,” Fuentes added. This also has resulted in an increased yield of the grass crop and fine fuels, while drier conditions become more likely in the summer, he said.
Additionally, there is potential for above-normal temperatures in August and September, primarily for the West, said Amber Motley, CAISO director of forecasting. The first half of summer could include above-normal temperatures that most likely wouldoccur in the northern and central portions of the West. There is a slightly lower chance of above-normal temperatures in coastal locations, she said.
