Three-year energy balance comparison between a utility-scale photovoltaic park and a managed conifer forest and effects on air temperature

Utility-scale ground-mounted photovoltaic power plants can represent a way to reduce greenhouse gas emissions and mitigate climate change. However, their development requires large land areas, creating land-use conflicts. Further, their influence on local climate remains poorly understood, particularly in temperate regions. We compare radiative and energy balances of a managed coniferous forest and a nearby photovoltaic park, and their effects on air temperature, using three years of continuous, innovative eddy covariance measurements. This rare dataset from temperate solar parks improves understanding of land-use change impacts, informing land selection and infrastructure design. Results revealed higher albedo in the photovoltaic park than in the pine canopy (0.13 vs 0.09), leading to net radiation 20% lower than in the forest. Consistent with lower available energy, heat fluxes above the park were reduced compared to the forest, particularly sensible heat flux in summer (227.6 ± 9.3 W m −2 vs 377.9 ± 56.6 W m −2 ). Despite these observations, daytime temperatures remained similar between sites. In the park, energy diverted to electricity production reduced the stored energy available for release, occasionally resulting in cooler nights and greater diurnal thermal variations than in the forest. The Bowen ratio, defined as the ratio of sensible to latent heat fluxes, was up to twice as high in the solar park as in the forest, indicating that sensible heat dominated energy partitioning despite evapotranspiration from the undergrowth. However, the park vegetation’s higher drought resistance maintained stable evapotranspiration, highlighting its regulatory role in moderating air temperature by limiting sensible heat flux.