A review of newly released EIA data shows utility-scale solar electricity grew 29% over the past year while battery storage expanded by 59%, according to the SUN DAY Campaign.
The group said solar set records in September as utility-scale output rose 36.1% year-on-year and small-scale systems increased 12.7%.
It added that combined solar provided 9.7% of US electricity for the month, up from 7.6% a year earlier.
The campaign said solar generation for the first nine months of 2025 grew 29.0% and supplied just over 9.0% of total output.
According to the analysis, utility-scale solar out-produced wind for the third consecutive month in September.
The group said year-to-date solar generation also exceeded hydropower by almost 65%.
Wind produced 9.8% of US electricity in the first nine months of 2025, up 1.3% on the year.
Wind plus solar supplied 18.8% of total generation, the campaign said.
It added that the mix of all renewables provided 25.6% of US electricity, second only to natural gas.
Between October 2024 and September 2025, utility-scale solar capacity grew by 31,619.5MW alongside 5923.5MW of small-scale additions.
Battery storage added 13,808.9MW of new capacity, an increase of 59.4%, the analysis said.
Wind expanded by 4843.2MW while natural gas capacity grew by 3417.1MW and nuclear added 46.0MW.
The group said coal capacity fell by 3926.1MW and petroleum-based capacity by 606.6MW.
It concluded that total renewable capacity including storage rose by 56,019.7MW while fossil fuels and nuclear combined fell by 1095.2MW.
“The Trump Administration’s efforts to jump-start nuclear power and fossil fuels are not succeeding,” said Ken Bossong. “Capacity additions by solar, wind, and battery storage continue to dramatically outpace gas, coal, and nuclear – and by growing margins.”