How to get photovoltaics on the roofs? : empirical evidence on the public support for a residential solar mandate in Germany

This study evaluates whether a residential solar mandate in the case of roof renovation is a useful complement to economic incentives for further photovoltaics (PV) adoption. Analyzing determinants affecting PV ownership and installation intentions among single-family homeowners, as well as factors influencing support for a solar mandate and perceptions of its effectiveness, our empirical results, based on a survey of German utility customers, show that a residential solar mandate is a rather unpopular policy measure among homeowners. However, a solar mandate addresses two important factors which, according to our results, increase the willingness to install PV: firstly, the perception that the personal environment expects more PV, and secondly, an upcoming roof renovation. Both social desirability and a favorable time window can be institutionalized through a solar mandate. In terms of support for a solar mandate, we find that the perceived effectiveness of such a mandate has a strong influence on homeowner support. Perceived effectiveness, in turn, is closely related to perceived cost savings and perceived environmental benefits of PV. Based on these results, we conclude that an active information policy regarding the environmental and cost implications of PV expansion is essential to increase the acceptance of a solar mandate.