According to a review by the SUN DAY Campaign of data recently released by the Federal Energy Regulatory Commission (FERC), renewable energy sources (biomass, geothermal, hydropower, solar, wind) dominated new U.S. electrical generating capacity additions during the first two-thirds of 2021. 
FERC’s latest monthly “Energy Infrastructure Update” report (with data through Aug. 31, 2021) reveals that renewable energy sources accounted for 86.46 percent—or 13,868 megawatts (MW)—of the 16,039 MW of new capacity added during the first eight months of the year. Wind led the capacity additions with 7,224 MW, followed closely by solar (6,585 MW). There were also small additions by hydropower (25 MW), geothermal (25 MW), and biomass (9 MW).
Most of the balance (2,155 MW) was provided by natural gas. There has been no new capacity added this year by coal and only 16 MW of new oil capacity have come online.
Renewables now provide more than a quarter (25.22 percent) of total U.S. available installed generating capacity. By comparison, a year ago, their share was only 23.22 percent. Five years ago, it was 18.39 percent and a decade earlier it was 14.09 percent.
Wind and solar alone accounted for 98.52 percent of the 1,554 MW of new capacity additions in July and August with natural gas providing just 23 MW. Wind is now more than one-tenth (10.48 percent) of the nation’s generating capacity while utility-scale solar has surpassed five percent (5.02 percent) … and that does not include distributed (rooftop) solar. 
Moreover, FERC data suggest that renewables’ share of generating capacity is on track to increase significantly over the next three years (by August 2024). “High probability” generation capacity additions for wind, minus anticipated retirements, reflect a projected net increase of 21,708 MW while solar is foreseen growing by 44,052 MW. By comparison, net growth for natural gas will be only 13,186 MW. Thus, wind and solar combined are forecast to provide roughly five times more new net generating capacity than natural gas over the next three years.
Including hydropower, biomass, and geothermal, net new renewable energy capacity additions over the next three years are projected to total 66,581 MW. This is nearly identical to the actual net additions of renewable energy capacity—65,820 MW—which FERC has reported for the last three years (since August 2018).
If FERC’s latest projections materialize, by August 2024, renewable energy generating capacity should account for almost 30 percent (29.44 percent) of the nation’s total available installed generating capacity.
Moreover, installed utility-scale solar capacity alone is on track to exceed that of nuclear power (106,060 MW vs. 104,620 MW) within that same time frame. In fact, new utility-scale solar capacity forecast to be added over the next three years (44,052 MW) will be more than 20 times greater than the capacity of the two new Vogtle nuclear reactors in Georgia (2,200 MW) that have been under construction since 2013.
“FERC’s data confirm that wind and solar are dominating new capacity additions in 2021 and are likely to continue doing so in the future,” notes Ken Bossong, executive director of the SUN DAY Campaign. “Nonetheless, to effectively address climate change, the pace of renewable energy growth needs to increase at an even faster rate.”
 Capacity is not the same as actual generation. Capacity factors for nuclear power and fossil fuels tend to be higher than those for most renewables. Thus, during the first half of 2021, the U.S. Energy Information Administration (EIA) reported that renewables accounted for 22.4% of the nation’s total electrical generation – that is, somewhat less than what FERC reported was their share (25.1%) of installed generating capacity for the same period.
 FERC generally only reports data for utility-scale facilities (i.e., those rated 1-MW or greater) and therefore its data do not reflect the capacity of distributed renewables, notably rooftop solar PV which – according to the EIA – accounts for about 30 percent of the nation’s electrical generation by solar. That would suggest that the total of distributed and utility-scale solar capacity combined is significantly more than the solar capacity of 5.02 percent reported by FERC — i.e., closer to 7 percent.
FERC’s six-page “Energy Infrastructure Update for August 2021” was released on Sept. 30, 2021. For the information cited in this update, see the tables titled “New Generation In-Service (New Build and Expansion),” “Total Available Installed Generating Capacity,” and “Generation Capacity Additions and Retirements.” FERC notes that its data are derived from Velocity Suite, ABB Inc. and The C Three Group LLC. and adds the caveat that “the data may be subject to update.”