SAN FRANCISCO—San Francisco has ranked as one of the top 20 Solar Cities by highest total rooftop and utility-scale solar installations and plans to transition to 100 percent renewable energy by 2020.

According to the report Shining Cities 2017, “How Smart Local Policies are Expanding in America” by the Environment Maine Research and Police Center, and Frontier Group released on April 4, 2017, the cities listed have nearly as much solar power as the entire country had installed at the end of 2010.

The state of California is adopting local policies that make solar energy the default. In 2016, San Francisco became the first major U.S city to require that solar energy systems be installed during the construction of new buildings. The report states that it is much easier and cheaper to install systems when the structure is designed for their inclusions and when there is already equipment on-site.

The Shinning Cities 2017 report made proposals to the government to reduce the cost of solar energy and to speed the distribution of renewable energy.

Among the proposals, the report suggests local government to implement programs and policies that promote that rapid expansion of solar energy, expanding access to all residents, installing solar energy systems on government buildings, and urging state and federal officials and investor-owned utilities to facilitate the growth of solar energy.

According to the report, these actions will be critical for the federal government to fulfill the commitments made in the Clean Power Plan and Paris Climate Agreement.

The research conducted by Environment Maine Research and Policy Center indicated that solar energy helps cities fight global warming and reduce air pollution, which would lead to positive effects on public health care.

According to the U.S Census Bureau, this report is the fourth review of solar photo-voltaic installations in U.S cities. This year, the list of cities to be surveyed started with the primary cities in the top 50 most populous Metropolitan Statistical Areas in the United States.