Photovoltaic policies show the primary effect of encouraging photovoltaic investments, but also secondary effects of crowding-in/out individuals with specific socio-psychological patterns. To enhance our understanding of such crowding effects, we investigated two comparative study cases with contrasting state support for photovoltaic investments: high financial support in the province of Bolzano/South Tyrol (Italy) versus lower financial support in the province of Styria (Austria). We surveyed individual and collective investors, and as a control group, households who had not invested in photovoltaics at the time of data collection. We first compared crowding effects of diverging PV policies, and afterwards individual and collective socio-psychological patterns to grasp their role for photovoltaic adoption in general. Protecting the environment was found to be the strongest driver for photovoltaic investments. Generous state support in Italy widened demographics, crowded in economic considerations and persons with an anthropocentric relationship towards nature. However, Italy's high-incentivized photovoltaic policy crowded-out the motivations for collective energy projects and could not sufficiently encourage a sustainable diffusion of photovoltaics, as investments collapsed once state funding was stopped.