Impacts of solar panels on vegetation biomass shift with climate aridity

Photovoltaic power generation provides a promising solution of future energy supply to achieve carbon neutrality. The rapid expansion of ground-mounted photovoltaic solar panels, however, has aroused concerns of potential negative impacts on ecosystems. Based on a global meta-analysis of paired field observations across 55 sites, we show that solar panels exert divergent impacts on aboveground biomass in the under-panel areas compared with the gap areas dependent on the trade-off between a shading effect and altered water relations. Specifically, solar panels on average cause a significant decrease in under-panel aboveground biomass by 38% (95% CI: -63% to -13%) in regions with aridity index (annual precipitation/potential evapotranspiration) above 0.26 (95% CI: 0.19 to 0.33), whereas no significant effect is found for regions with aridity index below this threshold. Using a criterion of aridity index below 0.26, we identify a global dryland area of 11.67 million km² where aboveground biomass is not decreased by the presence of infrastructure for photovoltaic solar power generation. Within these areas, we estimate that 71 countries have a potential capacity for photovoltaic solar power generation to meet their national electricity demands. Our study identifies an aridity threshold for the negative effect of solar panels on aboveground biomass and for the first time, sets up an ecological threshold for future solar power utilization in global drylands to reduce potential losses of ecosystem functioning.