Do Green Users Become Green Voters?

We estimate the causal effect of the diffusion of solar photovoltaic (PV) systems on the fraction of Green Party votes in federal and state elections in Baden-Württemberg, Germany. Our estimates are based on instruments that induce exogenous variation in roof appropriateness to PV installation. We find that PV adoption had a strong positive effect on Green Party votes. The effect is connected to the direct engagement of households with the PV system and does not reflect reciprocity to economic gains from PV. Our estimates likely reveal changing attitudes towards environmentally friendly values after adopting PV produced by cognitive dissonance.