Abstract: Background Saline-alkali lands provide substantial land resources for photovoltaic (PV) development. While PV infrastructure may alter subsurface hydrothermal conditions and offer new pathways for land reclamation, the spatiotemporal effects of PV arrays on soil salinity-alkalinity dynamics remain inadequately studied. This research addresses the critical knowledge gap regarding PV-driven microclimate-soil interactions in soda saline-alkali ecosystems. Methods We conducted field monitoring at the National PV and Energy Storage Empirical Platform (Daqing Base, Songnen Plain, China) during dry (May) and rainy (August) seasons to quantify local climatic variables, soil hydrothermal parameters (temperature, moisture, heat flux), and soil properties (pH, electrical conductivity (EC), exchangeable ions). Measurements were stratified underneath of photovoltaic panels and gap of photovoltaic arrays across dry and rainy seasons. Data were analyzed via ANOVA and randomForest modeling to identify key drivers of soil salinity-alkalinity patterns. Results 1) Microclimate restructuring: underneath of photovoltaic panels, wind speed decreased by 48.46% (dry season) and 69.53% (rainy season) (P<0.05), soil temperature reduced by 3.10℃ (dry) and 1.62℃ (rainy) (P<0.05), while soil moisture increased by 11.44% (dry) and 8.46% (rainy) (P<0.05) compared to gap of photovoltaic arrays. 2) Spatiotemporal salinity-alkalinity dynamics: Soil pH and EC were consistently lower in dry seasons and underneath of photovoltaic panels, EC at gap of photovoltaic arrays exceeded beneath-panel values by 31.92% during dry seasons (P=0.005). 3) Sodium-specific responsiveness: Na+ decreased significantly by 13.14% (underneath of photovoltaic panels) and 12.79% (gap of photovoltaic arrays) (P<0.01) during rainy seasons, with lower concentrations persistently observed beneath panels. The K⁺/Na⁺, Ca²⁺/Na⁺, and Mg²⁺/Na⁺ ratios consistently exhibited a spatiotemporal pattern of higher values during rainy seasons compared to dry seasons, and underneath of photovoltaic panels relative to gap of photovoltaic arrays. 4) Driving mechanisms: randomForest identified soil temperature as the dominant predictor for pH (%IncMSE=12.12) and EC (%IncMSE=14.64), modulated by array position and seasonal variation. Conclusions In summary, photovoltaic shading exerts wind-breaking, cooling, and humidifying effects beneath panels, ameliorating soil alkalinity and enhancing structural stability in the plough layer. This study provides a theoretical foundation for developing spatial utilization strategies featuring vegetation cultivation in gap of photovoltaic arrays zones and drainage systems underneath of photovoltaic panels to address rising pH and EC levels.