Optimizing the spectral sharing in a vertical bifacial agrivoltaics farm

Abstract

Abstract Agrivoltaics (AV) allows double usage of the land by yielding both food and energy. Such farms are more suitable for high population density locations like India. In this work, we study the impact of the vertical, bifacial AV farm on the rice (Oryza sativa) yield in a hot, tropical climate prevailing in the south-eastern part of India (Chennai, 13.0827° N, 80.2707° E). We compare two different bifacial silicon solar cell technologies: (a) passivated emitter rear contact (PERC+), and (b) silicon heterojunction (SHJ), using vertical configurations. We show that SHJ yields more energy than PERC for the considered location, mainly due to its high-temperature coefficient, high inherent bifaciality, spectral and the temperature advantage of the vertical configuration. To maximize both the rice and energy yield with equal importance, we discuss two strategies: (a) varying the pitch of the panels (2 m and 4 m) (b) optimizing the spectral sharing between the panels and plants by reflecting the photosynthetically active radiation incident over the panels (2 m pitch). We found that increasing the pitch of the panels (4 m pitch) could improve the rice yield but drastically reduces the energy yield (∼45% compared to an optimal photovoltaics (PV) farm). Using simulation, we show that by reflecting the small portion of the spectrum (400–500 nm) incident on the PV panels (an additional advantage of the vertical configuration), both the rice and energy yield could achieve a win–win situation (∼80% of rice yield compared to an open farm and 74% of the energy yield compared to an optimally tilted PV farm) with a higher land equivalent ratio of 1.54. The disadvantage of SHJs in the PV farm becomes advantageous in an AV farm due to its low dependence on the reflected portion of the spectrum compared to PERC+ solar cells. This work will motivate the development of low-cost technologies to make spectral sharing a viable option in the future, considering the limited availability of the land.