Variations of Solar Radiation and Their Impact on Rice Growth in Agrophotovoltaic System

Agrophotovoltaic (APV) or agrivoltaic (AV) systems, which combine the crop cultivation with solar energy production, emerge as a promising solution by leveraging the dual use of land. This two-year study (2023 and 2024) investigated APV system impacts on rice production. The findings indicated that APV arrays created spatially variable light envi-ronments, with shadow lengths following predictable solar azimuth patterns, cloudy conditions mitigated shading effects via enhanced diffuse light. Compared to CK (non shadow area), inter-panel plots (BP) maintained 77% photosynthetic efficiency and 85.4 % plant height, while beneath panel areas showed significant declines of SPAD values, photosynthesis rate and yield. BP plots preserved 78% fruiting rate through adaptive sto-matal regulation, while LP zones (directly under the low eave) showed 35% higher inter-cellular CO₂ due to limited assimilation in shading. Rice yield losses correlated with shading intensity, driven by reduced panicles and grain filling. In addition, the APV sys-tem achieved high land equivalent ratio of 1.48–1.49, which was combining 65-66 % rice yield with 82.5 % photovoltaic output. Based on the microenvironment created by the APV system, an optimal crop types and fertilization management are essential to enhance ag-ricultural yields and to improve land use efficiency.