Study finds 23% rice yield drop under solar panel shading in Japan

A six-year study (2018-2023) by the University of Tokyo investigated the impact of agrivoltaics on lowland rice cultivation in a temperate climate. Researchers examined a 1,416 m² field partially shaded by 57.96 kW of monocrystalline PV panels installed at 3.3 m height, covering 27% of the area. The study found that the agrivoltaic system lowered maximum air temperature by 0.8 °C, with no change in minimum temperatures. Average rice yield under the panels was 6.5 t ha⁻¹, a 23% reduction compared to the 8.5 t ha⁻¹ control yield, with yield loss linked to rainfall. Grain quality also decreased, showing more chalky grains and reduced head rice yield due to fewer panicles and lower biomass. The University of Tokyo recommended tailored crop management to mitigate shading effects and maintain stable rice yields.