Assessment of the ground coverage ratio of agrivoltaic systems as a proxy for potential crop productivity

The yield of crops in both agrivoltaic (AV) and agroforestry (AF) systems is difficult to predict. The shade pattern of an AV system is not typical and is quite different from the one of AF systems. Most countries allow AV systems on croplands only if the crop productivity is maintained (e.g., in France) or slightly reduced, as in Japan and Germany, with 80% and 66% minimum relative yield (RY) required, respectively. I suggest using the Ground Coverage Ratio (GCR: ratio of area of photovoltaic panels to area of land) as an indicator of the crop potential productivity in AV systems. The GCR can easily be computed and controlled for all kinds of AV systems with panels that are either fixed (horizontal, tilted, or vertical) or mobile (on 1- or 2-axis trackers). Here, I provide a synthesis of published data for crop productivity under AV systems. Only publications that provided both the GCR of the system and the crop RYs were included. Measuring RYs requires a reliable non-AV control plot. Several publications were excluded because of doubts regarding the measurements' validity (e.g., systems that are too small, resulting in strong edge effects, or unreliable control plots). Despite the scattering of results, a clear pattern is evidenced: RYs decrease rapidly when GCRs increase. It appears that a GCR < 25% is required to ensure that most crop RYs stay > 80%. These results are consistent with a recent meta-analysis examining the impact of shade on crops. The use of the GCR criterion to validate AV projects is a simple and cost-effective alternative to the tricky control of crop yields in the fields.

Automated summary

The yield of crops in agrivoltaic and agroforestry systems is difficult to predict. The Ground Coverage Ratio (GCR) can be used as an indicator of crop potential productivity in agrivoltaic systems, with a GCR < 25% ensuring most crop yields stay above 80%. This simple and cost-effective alternative can be used to validate agrivoltaic projects.