Ground-mounted solar parks are rapidly expanding in the Netherlands. It is critical to monitor their effects on vegetation, soil, and microclimate. We quantified the short-term impact of solar panels in thirteen solar parks across the Netherlands. Under solar panel arrays, vegetation cover, absolute species richness and Shannon diversity were reduced compared to the surrounding area. Day-time temperatures and temperature fluctuations were lower under solar panels, while soil and air moisture levels were higher. Directly north of solar panel arrays, absolute species richness and Shannon diversity were reduced, but vegetation was taller with a higher vegetation cover. Soil moisture was highest here. South of panel arrays, vegetation and soil parameters were comparable to the control situation without solar panels. Reduction of species richness depended strongly on previous land use and was highest in parks with high initial biodiversity value. It is therefore advised to avoid such areas in solar park allocation. By contrast, our findings suggest that enhancement of biodiversity is possible by planning solar parks in areas with low initial biodiversity value and proper solar park design and management (i.e. targeted at removal of nutrients and seeding of forb mixtures).