Impacts of agrivoltaic systems on microclimate, grain yield, and quality of lowland rice under a temperate climate

An agrivoltaic system is an emerging approach for establishing an integrated food–energy system that combines crop production and photovoltaic energy generation. However, maintaining high crop productivity with reduced solar radiation is a major concern for intensive farming. Our objective was to characterize the microclimate, grain yield, and quality of rice cultivated in an agrivoltaic system in a temperate climate. Field experiments were conducted at a lowland farm in Japan for 6 years, during the summers of 2018–2023. An agrivoltaic system that covered 27 % of the ground surface was established and the rice performance was evaluated. In the agrivoltaic system, the maximum air temperature was 0.8 °C lower than in the control, but the minimum air temperature did not differ. Grain yield decreased by 23 % on average (6.5 vs. 8.5 t ha −1 ). The relative yield (agrivoltaic/control) was significantly negatively correlated with the total rainfall. The rice quality traits were also affected, with a lower head rice yield, more chalky grains, and higher grain protein and amylose contents in the agrivoltaic system. The results confirmed our research hypothesis that grain yield in the agrivoltaic system would be limited by the reduced biomass and reduced panicle number, which are critical traits for rice productivity. Because rice productivity was sensitive to partial shading in the agrivoltaic system, particularly in rainy years, appropriate crop management practices must be developed to reduce the yield loss and stabilize the quality. • Gross return in lowland rice agrivoltaics was 14 times higher than the control. • Yield reduction in agrivoltaics was 23 % on 6-yr average (6.5 v 8.5 t ha −1 ). • Yield reduction correlated with total rainfall: lower yield in rainy years. • Higher panicle number contributed to higher crop biomass and yield. • Grain quality declined, marked by increased chalkiness and reduced head rice yield.