Jobs in the U.S. solar industry dropped around 7% last year because of work restrictions related to the COVID-19 pandemic and large gains in labor efficiency, an industry report published Thursday has revealed.

The decline extends a volatile period for solar sector jobs, which have yet to return to a peak reached in 2016 before the U.S. imposed tariffs on foreign-made panels that caused prices to surge.

Still, the solar sector is among the fastest-growing segments of the U.S. energy industry, driven by demand from businesses and governments seeking to source emissions-free and cheap power to satisfy taxpayer, customer and investor demands to address climate change.

There were 231,474 workers in the solar industry in 2020, down from 248,034 in 2019, according to the annual report from the Solar Energy Industries Association trade group.

It said a weakened economy and stay-at-home orders slowed demand for solar, particularly in the labor-intensive residential sector.

Labor productivity also increased 19% and 32% in the residential and utility-scale markets, respectively, because of shifts to online selling and an increase in the average size of projects.

The president of the Solar Energy Industries Association, Abigail Ross Hopper, which published the report, said she expected the decline to be temporary. “We will see lots more jobs created this year,” Hopper said.

U.S. President Joe Biden has vowed to decarbonize the U.S. economy by 2050, including the power sector by 2035. According to the analysis, it will take 900,000 solar workers to meet that goal.