The study was conducted by researchers at Chiba University, which aimed to investigate how agrivoltaic systems, also known as solar sharing systems, affect the yields of rice, soybeans, and sweet potatoes.
Under this system, the crops are grown under the shade of the solar panels installed over them.
According to the researchers, its study was the first to compare multiple crops, varieties, and cultivation methods under these systems.
Growing under 27 per cent shading, yields were found vary wildly ending on crop type, variety, and shading rate, with reductions ranging from 5 to 40 per cent.
The least affected was rice, with some varieties showing stable or even improved grain weights under panels.
Previous studies found that rice yields usually drop when grown under solar panels, but in this study, yields stayed stable.
The researchers highlighted a few reasons for this difference.
Firstly, the study used glutinous rice, which might respond differently to shade than the regular rice types studied before.
Additionally, the researchers suggested that rice could have a compensating mechanism.
Even though the number of panicles went down, each panicle had more spikelets and the grains were heavier, which made up for the loss.
Lastly, the study also noted that shading the rice crop at an early stage could potentially hurt the crop but improve the yield at a later stage.
Overall, solar sharing systems could provide an advantage in mitigating heat stress, suggesting a “dual-use” benefit that would be useful as global temperatures rise.
On the other hand, soybean and sweet potato yields were more sensitive to shading.
Soybean proved highly susceptible to shading, with seed yield decreased by 31% under 33% shading.
Reductions were noted across nearly all yield components, including the number of branches, nodes, pods, and seeds per plant.
Varieties matter
The study found that sweet potato was the most sensitive to shading, with yields declining sharply as shading intensity increased.
Conventional tuber weight per plant decreased by 40% under 31% shading.
With organic sweet potatoes, tuber yield decreased by 42% in 2023 and 49% in 2024 under 40% shading.
The study highlighted that high tolerant varieties, Karayutaka and Amahazuki, showed no significant yield reduction under shading in certain trials.
On the other hand, low tolerant varieties like Anno and Beniharuka consistently exhibited significant yield losses.
Shade avoidance
Another key finding of the research was that yield reductions were driven by Shade Avoidance Response (SAR), not just decreased photosynthesis.
SAR is an evolutionary response that causes plants to reallocate resources to compete for light.
Low tolerant sweet potato varieties, Anno and Beniharuka, displaced strong SAR.
To ensure the viability of staple crop production within agrivoltaic systems, the researchers suggested selecting “shade-tolerant” varieties.
Additionally, they said crop-specific shade limits should be established, noting that shading levels near 30% appeared acceptable for rice.
On-farm agrivoltaic impacts on main crop yield: the roles of shade avoidance, cultivation practices, and varieties
npj Sustainable Agriculture
Authors: Noriko Maruyama et al.
https://doi.org/10.1038/s44264-025-00121-w