American rooftop solar power is growing at a stunning rate, a new study finds, with solar capacity increasing 19% in 2021.
The United States now has 121.4 gigawatts of solar photovoltaic capacity, enough to power 23 million homes, up from just 0.34 gigawatts in 2008, according to the Department of Energy.
Cities located in the Southwest and on the West Coast are, by and large, way ahead of their northern and eastern counterparts at getting solar panels on rooftops, according to a new study from Environment America Research & Policy Center, a think tank, and Frontier Group, a research organization affiliated with the Public Interest Network.
“The amount of solar power installed in just nine U.S. cities exceeds the amount installed in the entire United States 10 years ago,” the report, titled “Shining Cities 2022,” found. In fact, 15 of the 56 cities included in the study increased their solar capacity tenfold since 2014.
According to the Intergovernmental Panel on Climate Change, clean sources of energy such as wind and solar power must account for the vast majority of electricity within the next few decades to avoid catastrophic climate change.
The top five per capita solar power producers are Honolulu, Las Vegas, San Diego, Albuquerque and San Jose, Calif., in that order. The rest of the top 19 cities include several more in California (Los Angeles, Sacramento and Riverside); a few from nearby states, including Phoenix and Salt Lake City; and several from the South, such as New Orleans. The only cities on the list of the top 19 producers that are not located in the West or Southwest are Burlington, Vt. (in seventh place), Washington, D.C. (10th), Indianapolis (16th), Hartford, Conn. (17th), Newark, N.J., (18th) and Charleston, S.C. (19th).
There are a variety of factors that determine the rate of solar deployment, including state and local policies, energy prices, climate and housing stock, among others. Southern and Western cities may lead in part because of their abundant sunshine, leaving ample room for rooftop or backyard solar arrays. By contrast, cities in the Northeast and Midwest may lag partly due to rainier weather.
Nationally, the changing economics of solar power have driven the sector’s explosive growth. The average cost of solar panels has dropped 70% since 2014, according to the Department of Energy.
Cost is also a reason that some states have gone solar much faster than others. Hawaii and California have the highest and third-highest electricity prices in the country, respectively, giving homeowners more incentive to reduce their bills by producing their own energy.
State policies also play an important role. For example, cities in Florida rank near the bottom of the list because until 2018 the state prohibited residents from leasing solar panels so they could pay for them in increments.
The report’s authors note that policies to encourage solar deployment have also been key to increasing adoption.
“Much of the recent growth of solar energy is the result of public policy,” they write in the report. “Federal tax credits for renewable energy have played a key role in encouraging growth in solar power (although, the current solar investment tax credit of 26% is slated to fall to 22% in 2023 and disappear entirely for residential systems in 2024).”
As part of his effort to halve the greenhouse gas emissions causing climate change by 2030, President Biden has proposed new federal tax credits for solar panel purchases, and the House of Representatives passed a bill including that and other domestic spending, but it has been blocked in the Senate by Republicans and Sen. Joe Manchin, a Democrat from the coal- and gas-heavy state of West Virginia.
State governments and their utility regulators are facing pressure from energy utilities to remove the practice known as “net metering,” in which utilities buy solar power from homeowners at the retail rate that they pay larger energy providers. The report’s authors warn that such moves could hamper the future growth of residential solar adoption.
“In some states, including California and Florida, key policies that have provided a solid foundation for the growth of solar power are now under threat,” they write. “This includes ‘net metering,’ the critical practice of crediting solar energy customers for the excess energy they supply to the grid. The outcome of these debates will determine how rapidly cities and the rest of the nation can gain the benefits of solar energy.”
In addition to maintaining net metering and extending solar tax credits, the report calls for local governments to streamline the permitting process for solar panels and to “expand access to solar energy to apartment dwellers, low-income residents, small businesses and nonprofits through community solar projects, virtual net metering and third-party financing options such as power purchase agreements.”
The report also comes amid a flurry of good news for renewable energy. Earlier this month, California set a record when its power grid briefly ran on 97% renewable energy. And on March 29, wind power passed a milestone when it became the second-largest source of electricity in the U.S., after natural gas, for a 24-hour period.