Evaluating the Spatial Trends and Statistical Determinants of Residential Solar Uptake in Washington State

Washington State’s Clean Energy Transformation Act and other state and federal policies encouraging solar power make Washington a ripe candidate to examine growth, trends, and potential determinants or barriers to residential solar uptake. In this thesis, residential solar is cumulatively and annually mapped by county (2000-2019) and Census tract (2017-2019) across the state to identify trends over time and space. Each variable (income, age, households, race, education, solar insolation, cost of solar per watt) was isolated individually to analyze the relationship (if any) to the dependent variable (i.e., residential solar installations). The covariates are then combined into a multiple regression model to examine their explanatory power. Finally, an annual fixed effect multiple regression model is used to identify policy events or economic conditions not being accounted for in the dataset. Collectively these variables help describe the overall drivers and growth of solar installations (2011-2019). Though more data is necessary to develop a more holistic understanding, it is certain that uptake is drastically impacted when subsidy policies are in limbo. Many consumers are delaying the investment until the policy frameworks are concrete, with legislation existing to support the consumer