Solar and wind together accounted for 88% of new US electrical generating capacity added in the first eight months of 2025, according to data just released by the Federal Energy Regulatory Commission (FERC) which was reviewed by the SUN DAY Campaign. In August, solar energy alone provided two-thirds of the new capacity, marking two consecutive years in which solar has led every month among all energy sources. Solar and wind each added more new capacity than natural gas did. Within three years, the share of all renewables in installed capacity may exceed 40%.

In its latest monthly “Energy Infrastructure Update” report (with data through August 31, 2025), FERC says 48 “units” of solar totaling 2,702 megawatts (MW) came online in August, accounting for 66.4% of all new generating capacity added during the month. That represents the second-largest monthly capacity increase by solar in 2025, behind only January when 2,945 MW were added.

The 505 units of utility-scale (>1 MW) solar added during the first eight months of 2025 total 19,093 MW and accounted for 73.4% of the total new capacity placed into service by all sources.

Solar has now been the largest source of new generating capacity added each month for two consecutive years, between September 2023 and August 2025. During that period, total utility-scale solar capacity grew from 91.82 gigawatts (GW) to 156.20 GW. No other energy source added anything close to that amount of new capacity. Wind, for example, expanded by 11.16 GW while natural gas’ net increase was just 4.36 GW.

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Between January and August, new wind has provided 3,775 MW of capacity additions – more than the new capacity provided by natural gas (3,095 MW). Wind thus accounted for 14.5% of all new capacity added during the first eight months of 2025.

For the first eight months of 2025, the combination of solar and wind (plus 4 MW of hydropower and 3 MW of biomass) accounted for 88.0% of new capacity, while natural gas provided just 11.9%. The balance of net capacity additions came from oil (20 MW) and waste heat (17 MW).

Utility-scale solar’s share of total installed capacity (11.62%) is now almost equal to that of wind (11.82%). If recent growth rates continue, utility-scale solar capacity should equal and probably surpass that of wind in the next “Energy Infrastructure Update” report published by FERC.

Taken together, wind and solar make up 23.44% of the US’s total available installed utility-scale generating capacity.

Moreover, almost 29% of US solar capacity is in the form of small-scale (e.g., rooftop) systems that are not reflected in FERC’s data. Including that additional solar capacity would bring the share provided by solar + wind to more than a quarter of the US total.

With the inclusion of hydropower (7.59%), biomass (1.06%), and geothermal (0.31%), renewables account for a 32.40% share of total US utility-scale generating capacity. If small-scale solar capacity is included, renewables make up more than one-third of total US generating capacity.

FERC reports that net “high probability” net additions of solar between September 2025 and August 2028 total 89,953 MW – an amount almost four times the forecast net “high probability” additions for wind (23,223 MW), the second fastest-growing resource.

FERC also foresees net growth for hydropower (566 MW) and geothermal (92 MW), but a decrease of 126 MW in biomass capacity.

Meanwhile, natural gas capacity is projected to expand by 8,481 MW, while nuclear power is expected to add just 335 MW. In contrast, coal and oil are projected to contract by 23,564 MW and 1,581 MW, respectively.

Taken together, the new “high probability” net capacity additions by all renewable energy sources over the next three years – i.e., the Trump Administration’s remaining time in office – would total 113,708 MW. On the other hand, the installed capacity of fossil fuels and nuclear power combined would shrink by 16,329 MW.

Should FERC’s three-year forecast materialize, by early fall 2028, utility-scale solar would account for 17.1% of installed U.S. generating capacity, more than any other source besides natural gas (40.0%). Further, the capacity of the mix of all utility-scale renewable energy sources would exceed 38%. Including small-scale solar, assuming it retains its 29% share of all solar, could push renewables’ share to over 41%, while natural gas would drop to about 38%.

“Notwithstanding impediments created by the Trump Administration and the Republican-controlled Congress, solar and wind continue to add more generating capacity than fossil fuels and nuclear power,” noted the SUN DAY Campaign’s executive director Ken Bossong. “And FERC foresees renewable energy’s role expanding in the next three years while the shares provided by coal, oil, natural gas, and nuclear all contract.” 

Read more: EIA: Solar + storage dominate, fossil fuels stagnate to August 2025

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