Solar power installations marked a new high in 2016. The U.S. now has 42 gigawatts of solar photovoltaic energy capacity, sufficient to power 8.3 million homes and reduce carbon dioxide emissions by 52.3 million metric tons annually. The solar capacity grew by 55 percent year-over-year, according to an analysis released by Environment America Research and Policy Center. The report, “Shining Cities: How Smart Local Policies Are Expanding Solar Power in America,” shows that the top five positions are occupied by San Diego, Los Angeles, Honolulu, San Jose and Phoenix. An impressive number of American citizens have invested in their own solar projects in their communities, while many more are ready to enroll. In 2016, just the top 20 cities accounted for as much solar power capacity as the entire country had installed in 2010, nearly 2 gigawatts. There is also a new number one solar-powered city, San Diego, which is replacing Los Angeles. But even though the industry marked such great progress last year, there are still vast amounts of untapped solar potential. San Diego, for instance, has developed less than 14 percent of its technical potential for solar energy on small buildings. “San Diego is setting the standard for other cities across the country when it comes to protecting our environment and creating a cleaner future,” San Diego Mayor Kevin Faulconer said. “This new ranking is a testament to the many San Diego residents and businesses harnessing our natural resources as we march toward our goal of using 100 percent renewable energy throughout the city.” In order to shift the U.S. toward an economy powered by 100 percent renewable energy, officials must continue to adopt a series of pro-solar policies. “Cities are recognizing that clean, local and affordable energy just makes sense,” said...