Incentivizing winter solar PV production in regions with seasonal weather patterns: case study of Switzerland

Abstract An increasing number of countries are committing to carbon neutrality and plan a massive rollout of solar photovoltaics (PV) to meet this goal. Owing to its seasonal production patterns, solar PV electricity will become less valuable during summer and more valuable during winter, when electricity prices increase accordingly. Consequently, optimizing PV plants to balance seasonal production variability will become increasingly important. This can be achieved via deploying PV in locations with higher irradiation in winter and/or by changing the angle of PV panels. Current solar PV support policies overlook production seasonality, risking a lock-in of projects optimized for annual production, which is dominated by irradiation during the summer. Here, we analyze household-scale rooftop PV in Switzerland, applying a cash flow model to evaluate policies designed to boost winter solar production. Our findings show that seasonally differentiated feed-in tariffs increase the economic incentives for winter electricity generation in areas with the highest winter solar potential. By contrast, investment subsidies, which are resource agnostic, prove less effective in directing PV to high-resource locations. This analysis underscores the importance of regionally tailored policies to promote winter-adjusted PV plants, an approach transferable to regions with seasonal solar variation, and large geographic altitude differences.