This paper evaluates the effectiveness and cost efficiency of government policies promoting residential solar adoption in New York. Using a dynamic discrete choice model estimated with panel data on installations, demographics, and policy variation, the analysis examines how forward-looking households respond to subsidies, tax incentives, and net metering. Results show that federal and state tax credits are the most effective in encouraging adoption, followed by the capacity-based subsidy. Counterfactual simulations indicate that removing the subsidy would have significantly reduced adoption, while welfare analysis reveals that the social benefits of these programs amount to roughly 60% of their total costs, underscoring the need for more cost-effective policy design.