The number of U.S. homeowners putting solar panels on their roofs declined last year after leading installers including Tesla Inc. abandoned aggressive sales practices that had helped drive breakneck growth.
Residential solar had been on a tear, averaging 48.6% annual growth between 2010 and 2016, but the number of megawatts added last year dropped by 15.6% compared to the year before, according to new data from GTM Research, a firm that tracks renewable energy. It was the first annual decline since at least 2000, as far back...