Compared to the growing number of utility-scale solar farms (USFs) sitting in hilly regions, knowledge of the hydrological behaviors in responding to the installation of USFs in these environments remains limited. We present herein a novel model (the Solar-Farm model) to understand the hydrological behaviors following the construction of a USF in the Loess Hilly Region of China, by combining it with an index of hydrological connectivity (HC). Scenarios were designed to estimate the effects of climate and terrain in controlling the effects of the USF on soil erosion, by altering the mean annual precipitation amount, the frequency of precipitation events, and the relief amplitude. Our results show that land use changes (e.g., vegetation removal) incurred a considerable increase in the accumulative soil erosion (22.45%-66.48%) during the installation period. During the 40-year deployment period, photovoltaic panels (PVs) incurred an average of 0.138 m deeper erosion in the USF compared with the background rate without PVs. A wetter climate induced the highest increase (88.25%) in erosion. However, the relief amplitude and precipitation frequency are also confirmed as important controlling factors for soil erosion (increased by 85.42% and 58%, respectively). The HC was increased during both the construction (0.005-0.12) and operation periods (0.149-0.314). Correlation analysis presented that the landscapes with higher HC were more likely to be exposed to the risks of soil erosion. USFs could increase soil erosion by increasing runoff and local HC, and higher background HC in turn could further aggravate the effects of USFs on soil erosion.