Photovoltaic (PV) facilities play a pivotal role in restructuring energy systems and mitigating carbon emissions. However, they also alter local microclimates and ecohydrological conditions, especially in arid and semi-arid regions. Most existing studies focus on individual environmental factors and overlook the coupled interactions among soil, vegetation, atmosphere, and PV infrastructure. To address this, we developed a novel soil-plant-PV-atmosphere continuum (SPPVAC) model that integrates airflow, heat, and moisture transport processes with vegetation dynamics. The model was validated with field observations and applied to a representative PV site in Zhangjiakou, northern China. Results show that PV facilities reduce wind speed by 27.6-42.3 %, increase air temperature by 2.31 degrees C, and raise humidity by 35.8 % in sheltered areas. These microclimatic changes enhance biomass productivity of soybean, alfalfa, and parsnip by 48.3 %, 42.9 %, and 26.7 %, respectively. Crops with higher leaf area density exhibited stronger transpiration and microclimate regulation. This study provides an integrated simulation framework to evaluate microclimate-vegetation feedback under PV systems and offers crop-specific insights for optimizing agrivoltaic design. The findings highlight the potential of PV infrastructure to support both renewable energy generation and ecological restoration.