Ground-mounted photovoltaic solar parks promote land surface cool islands in arid ecosystems

Despite the growth rates of photovoltaic solar parks, their potential to alter land surface temperature remains unclear. Yet, resolving temperature impacts is pivotal to understanding the implications for ecosystem function, and the consequences for society due to perturbations to ecosystem service supply and natural capital stores. Here, for the first time, we demonstrate the existence of a solar park land surface temperature cool island effect that extends beyond the solar park boundary, using Landsat satellite imagery. The cool island effect was quantified for two large ground-mounted solar parks, Longyangxia (850 megawatts) in China and Stateline (300 megawatts) in the United States of America, where the effect was confirmed using field-based measurements. At both sites, the cooling extended up to 730 m away from the solar park boundary with localized reductions in LST of up to 2.3 °C. These cool islands could affect large areas of the land surface as solar parks proliferate across the world, with notable positive or negative impacts on ecosystem function. Given the potential implications for ecosystem processes, including carbon feedbacks to climate change and the carbon intensity of the electricity produced, improved understanding of solar park LST impacts is required. Specifically, this knowledge is needed to inform the development of sustainable land use and energy policies considering the rapid growth of solar park developments.