Implications of spatial-temporal shading in agrivoltaics under fixed tilt & tracking bifacial photovoltaic panels

The spatial and temporal behavior of the incident sunlight can have important implications for agrivoltaic (AV) crop yield. Here we explore the short term (daily) and long term (monthly) variations of the photosynthetically active radiation (PAR) under various tracking and fixed-tilt agrivoltaic PV modules configurations and propose strategies to minimize the shade-induced crop yield loss. For a fixed row to row PV module spacing, vertically installed PV modules facing East/West provide the best spatial homogeneity and a higher intensity of net daily incident PAR, while the traditional North/South faced fixed tilt PV modules result in a high spatial contrast, i.e., a significantly lower PAR underneath the PV modules as compared to the open space between the adjacent rows of PV modules. The shading behavior for the horizontal single axis tracking PV modules shows a seasonal dependence, a higher shading vertically below the PV modules during winters and vice versa for summers. The spatial variation in the crop yield correlates well with that of the net daily PAR spatial pattern in the case of the shade sensitive crops (e.g., tomato) while the spatial yield for the shade tolerant crops (e.g., lettuce) is less affected by PAR variations. We propose an intercropping approach where the cultivated areas for crops having high and low shade sensitivity are identified based on the calculated spatial PAR pattern. A case study of intercropping lettuce with tomato under various PV module configurations shows that this approach can minimize the biomass loss for shade sensitive crops in the presence of spatial PAR heterogeneity.