Evaluating the contribution of decreasing heights of photovoltaic panels on light environment and agricultural production in agrivoltaic systems

Abstract

Agrivoltaic systems (AVS) are an emerging model that combines green energy and agricultural production offering several benefits, including improved utilization of renewable resources and land. However, the impact of photovoltaic (PV) panels on the light environment and corresponding influence on crop growth is poorly understood. This study aims to quantify the impacts of the height of PV panels on available light, photosynthetic characteristics and yield of crops to aid system design. An AVS in Nanjing, Jiangsu, with PV panel heights of 2.5, 3.2, and 3.9 m, was taken as the research object. A row of fig trees were planted in the area between PV panels. The results showed that the available light in the area between the panels was in the range of 54.1%–67.1% relative to fully exposed areas, which was in turn 2.1 to 3.2 times that in the area under the panels. The available light in the area between the panels decreased as the height of the PV panels increased, with a reduction of 13.0%, while the opposite trend was observed in the area under the panels, with an increase of 4.7%. These results agreed with numerical simulations, which modelled the light environment models of AVS, providing a further means of altering system design. Furthermore, the average fig yield of each treatment was reduced by 19.8%–48.8% compared to the open field, with PV panels at a height of 2.5 m providing the highest yield of systems tested. The photosynthetic performance of fig leaves was consistent with the yield differences between treatments. This study reflects the light environment in common AVS found in China, with optimal panel heights of 2.5 m for fruit trees such as figs. Additionally, the methods adopted in this study provide a valuable resource in optimizing AVS design for different locations and in combination with physiological understanding of different crops.