California

Did California's Solar Mandate Increase Solar Adoption?
California’s rooftop solar mandate substantially increased adoption, but evaluating a policy requires more than measuring its effect.
Béla Figge
Last updated on Jul 29, 2026 7 min read Research
The Strange Economics of Rooftop Solar
Earlier engineering studies suggested rooftop solar would pay off on nearly all new California homes. Our project-level analysis found a more complicated story.
Béla Figge
Last updated on Jul 29, 2026 8 min read Research
Solar Adoption by Mandates
Rooftop solar photovoltaic mandates are becoming a popular policy across Europe and the United States. In this paper, we leverage the …
Béla Figge, Stefano Carattini, Wade Davis, Anton Heimerdinger
PDF Project Writing series The Solar Gap
Solar Adoption by Mandates
Solar mandates are spreading rapidly. We leverage California’s frontrunner experience to examine their economics. First, we …
Béla Figge, Stefano Carattini, Wade Davis, Anton Heimerdinger
PDF Project Writing series The Solar Gap