Stormwater-Retaining Ground Surface Depressions of Solar Photovoltaic Farms

Solar photovoltaic (PV) farms are commonly used for harnessing renewable solar energy, but they will change the natural landscape. Surface depression storage refers to the maximum empty volume that precipitation can fill on a surface before runoff occurs. This study aimed to determine the surface depression storage depths and volumes of a solar PV farm and assess the impact of solar PV panels on them. A solar PV farm with a grassy land surface was chosen and divided into six subwatersheds with varying topographic characteristics. Terrestrial laser scanning (TLS) point cloud and its triangulated irregular network (TIN) were utilized to identify and quantify surface depressions. The results showed that the microtopography of the grassy land surface between and under solar PVPs and the components commonly found in solar PV farms were accurately captured compared with field observations. The rainfall-retaining depression depths at solar PV farms were found to span 0.91-12.63 mm, which, among other applications, would provide new reference values for watershed models. The study also found a positive correlation between the surface depression storage depth and the area ratio of solar PVPs. Moreover, this study isolated the impact of solar PV farms on surface depressions from the underlying grassy surfaces and revealed that a deviation in the area ratio of solar PVP from one-third will result in a deviation of depression depths from the underlying grassy land surfaces. This study provides reference data on rainfall-retaining ground surface depression depths of solar PV farms as well as offers direction for future solar PV farm installations, considering various solar PVP area ratios.