From Executive Summary:

The use of solar power is expanding rapidly across the United States. By the end of 2014, the United States had 20,500 megawatts (MW) of cumulative solar electric capacity, enough to power four million average U.S. homes. This success is the outcome of federal, state and local programs that are working in concert to make solar power accessible to more Americans, thereby cleaning our air, protecting our health, and hedging against volatile electricity prices.

America’s major cities have played key roles in the clean energy revolution and stand to reap significant benefits from solar energy adoption. As population centers, they are home to the largest electricity markets and can have an important influence on the way we power our grid. Many cities are already benefitting from smart policies that encourage investment in solar energy.

As of the end of 2014, 20 cities – representing just 0.1 percent of U.S. land area – account for 6.5 percent of solar photovoltaic (PV) capacity in the United States. The 65 cities in this report have installed 1.3 gigawatts (GW) of solar PV capacity – more solar PV than was installed in the entire country at the end of 2009. Los Angeles leads the nation in total installed solar PV capacity, followed by San Diego, Phoenix, Indianapolis and San Jose.