Installing solar panels on your roof is not just for tree-hugging environmentalists. The increasing ease of the process and the financial returns have made going solar practically mainstream. Washingtonians are embracing solar power in a big way. In the District, residential solar installations have tripled since 2011, said Chelsea Barnes with EQ Research. “By the end of 2020, the amount of installed solar capacity will be 300 percent higher than today,” said Dan Whitten, vice…