This study investigates the impact of an agrivoltaic (APV) system on evapotranspiration (ET) and soil moisture dynamics by comparing experimental ET measurements with theoretical estimates using the FAO-56 Penman-Monteith equation. A field experiment was conducted using lysimeters to measure ET within an APV system and an open-field reference plot. The results indicate that ET rates were consistently lower in the APV system due to the shading effect of PV panels, which reduced solar radiation exposure and enhanced soil moisture retention. The exclusion of precipitation-affected data improved the accuracy of ET measurements, highlighting the necessity of precise data selection in similar studies. Although discrepancies between experimental and theoretical ET values were observed, they were attributed to measurement limitations and microclimatic variations. The findings suggest that APV systems can contribute to sustainable water management by reducing water loss and irrigation demands, particularly in arid and semi-arid regions. Further research is recommended to assess long-term impacts on crop yield and optimize APV configurations for diverse agricultural environments.