A standardized research design to assess the impacts of solar parks on biodiversity and ecosystem services across Switzerland

Climate change and biodiversity loss are tightly linked and among the most urgent global challenges. Switzerland aims for net-zero CO2 emissions by 2050 while conserving biodiversity, which accelerates the transition to renewable energy. With the Federal Act on the Secure Supply of Electricity from Renewable Energy Sources, understanding and minimizing the ecological impacts of solar parks has become urgent. In its Biodiversity Strategy and Action Plan, the Federal Office for the Environment calls for integrating biodiversity into energy planning. Despite political incentives, major knowledge gaps remain on how ground-mounted photovoltaic (PV) parks affect biodiversity, ecosystem functioning, and ecosystem services, especially in temperate regions. High-alpine PV parks are particularly controversial: their production profile could help mitigate the winter electricity shortfall, but they may also increase pressure on sensitive alpine ecosystems. Empirical evidence is limited and rarely comparable across sites and elevations. Key unknowns include which taxa and ecological functions are most sensitive, whether responses differ along elevational gradients, and how impacts relate to the surrounding landscapes and legacy.

To close these gaps, we propose a standardized research scheme for nationwide implementation. The scheme integrates assessments of solar panel impacts on biodiversity and ecosystem functioning below- and aboveground, and on ecosystem services such as soil formation, biomass production (e.g. for fodder), pollination, and regulation of the microclimate. Microclimatic variables are measured to relate local conditions to broader climate patterns, while vegetation dynamics are analyzed in the context of surrounding landscapes and land-use legacies. Standardized surveys of vegetation, soil microbes, and arthropods provide comprehensive insights to biodiversity responses. These are complemented by assessments of polarized-light effects on insects and birds and by evaluating habitat provisioning through increased structural complexity. Implemented nationwide, the scheme would generate the evidence base needed to guide a biodiversity-friendly expansion of solar energy and support an energy transition which aligns with Switzerland's Biodiversity Goals.