Tracing residential PV adoption journeys: A process-oriented understanding of technology adoption and the role of peer-based initiatives

Given solar energy’s central role in energy transitions and its significant potential on residential buildings, understanding household PV adoption decisions is crucial for effective policy design and achieving national energy goals. This study provides a process-oriented perspective on residential PV adoption in Switzerland and Germany, examining the mechanisms shaping household decision-making and the role of peer-based initiatives therein. Drawing on Diffusion of Innovation theory and the Transtheoretical Model, we conceptualize PV adoption as a socially embedded, stage-based process in which social interactions and contextual constraints influence both attitudes and the translation of intention into action. Using an exploratory, longitudinal, mixed-methods design, we combine surveys conducted before and after community-led peer-based PV events with in-depth qualitative interviews, tracing adoption trajectories of 16 study participants (12 Swiss, 4 German) over time and exploring factors associated with progress and stagnation. Our findings suggest that early adoption phases are often influenced by windows of opportunity such as building renovations, in addition to favorable socio-demographic conditions, positive attitudes toward PV, mass media and exposure to peer influence. Progress into later stages appears to depend on a narrower set of conditions, including favorable building characteristics, high perceived self-efficacy and economic viability, recommendations from others, and access to trusted, experience-based information. Peer-based events reveal particularly effective during the evaluation phase, where peer learning in trusted, local settings can enhance procedural confidence and resolve contradictory or uncertain information from suppliers. Adoption trajectories are frequently delayed or halted by complex renovation projects, financial constraints, time limitations, and coordination challenges, especially in multi-actor settings. We conclude that strategies supporting residential PV adoption should be tailored to specific adoption phases. Proactive advisory services timed around building events, predictable long-term incentives, streamlined administrative processes, and sustained community-led peer initiatives appear particularly promising for accelerating adoption while mitigating delays in complex decision-making contexts.