Interdisciplinary modelling in support of people-centred transitions: Forecasting citizen adoption of rooftop PV systems under alternative sociopolitical future-world evolutions

Rooftop photovoltaic (PV) systems are central to decentralised solar transitions in Europe, yet their diffusion depends on more than technical potential, technology costs, or the formal design of support schemes. As Member States move from guaranteed remuneration mechanisms towards more market-reflective compensation, rooftop PV adoption increasingly depends on how citizens perceive policy credibility, profitability, social influence, and uncertainty. This article investigates citizen adoption of rooftop PV systems in the Greek residential sector by 2030 under three alternative sociopolitical storylines representing citizen-driven, government-directed, and market-driven future-world evolutions. We operationalise an interdisciplinary modelling framework that sequentially couples sociopolitical storyline development with agent-based technology adoption modelling. The framework is applied to assess the recently introduced net billing scheme, both as a standalone policy and in combination with battery energy storage system subsidisation, and to benchmark its performance against former feed-in tariff and net metering designs. Results show that the former net metering scheme remains the most effective design by 2030, while net billing ranks second and remains comparatively robust when combined with storage. However, none of the analysed schemes is sufficient, on its own, to achieve the national target of 1 GW of residential rooftop PV capacity by 2030. Adoption outcomes vary across storylines and behavioural profiles, indicating that policy effectiveness is shaped by perceived profitability, policy maturity, social learning, investment resistance, and trust in the stability of the support framework. The study shows how compensation mechanisms translate into adoption trajectories under behavioural and sociopolitical uncertainty, supporting more adaptive and citizen-centred policy designs.