The synergistic effects of reflective sheets and photovoltaic panels in agrivoltaics: a study on taro

Agrivoltaics involves a trade-off between the negative impact on shade-intolerant crop growth caused by panel shading and the positive impact of electricity generation. Although taro is known as a shade-tolerant crop, the effect of shade from the panels on reducing soil temperature and the effect of installing reflective sheets to increase bilateral photovoltaic power generation and reduce soil temperature have not been verified. This study used an experimental field with wooden panels that shade solar radiation and reflective sheets that strongly reflect solar radiation and examined the effects of shade and reflective sheets. It shows that the land equivalent ratio (LER) can be significantly greater than one in high shade plots (GCR, ground cover 29%). The reflective sheets not only estimated to increase the amount of electricity generated by approximately 20%, but also improved taro yield by lowering soil temperature. For panels with a GCR of 29%, the LER improves from 1.65 to 2.12 in 2021 and from 1.90 to 1.94 in 2023 due to the reflective sheets. Even under a lower GCR of 14% without reflective sheets, the LER exceeded 1.0, reaching 1.42 in 2025. Box–Cox-transformed random-intercept linear mixed-effects models showed significant associations of quantitative GCR, reflective-sheet treatment, and experimental year with taro yield, together with a strong reflective-sheet × year interaction. The findings indicate that shade has the positive effect of reducing midsummer soil temperature, demonstrating that shade has an additional positive effect on the yields of shade-tolerant crops. Agrivoltaics of taro using reflective sheets has shown promise as a system that can sustainably produce both crops and electricity.