Do communities struck by disaster build back better, or not? Recent small- and medium- N studies have shown mixed effects. This mixed-methods study tests the effect of disasters on the adoption of solar power as a key form of building back better and adapting to climate change. To test this effect, we applied a large- N longitudinal matching experiment on cities affected and unaffected by disaster paired with qualitative case studies, focusing on the 2011 triple disaster in Japan and Hurricane Sandy in 2012 in the United States. We find that disaster-hit cities adopt more solar farms and rooftop solar than cities unaffected by crisis and that the social capital of these disaster-hit communities shapes their adoption patterns. By clarifying the effects of disasters on the build-back-better phenomenon in comparative cases, this article aims to guide recovery priorities after large-scale shocks.