The state of solar in California The number of sunny days per year ranges between 250 and 290 for most locations in the Golden State, placing California among the top five sunny states.* In contrast, the national average is only 210 sunny days per year. According to Project Sunroof, a whopping 91% of the buildings in California are solar-viable, with a total of 11.5 billion square feet of roof space fit for solar installations.* This promising data, coupled with the state’s commitment to reach a 100% zero-carbon energy goal by 2045 and multiple statewide clean energy incentives, makes it easy to understand why California occupies the first place of the Solar States Top 10 .* Currently, over 8.5 million homes in California rely on solar energy.