Vertical Agrivoltaics System: What Solar Radiation to Share Between Agriculture and PV Modules?
Résumé
Agrivoltaics, which combines agricultural production with solar energy generation, addresses the water-food-energy nexus, enhancing resilience in both energy and food supply systems. This concept necessitates evaluating the synergies between agricultural and photovoltaic (PV) production. Specifically, this work delves into the physical interactions between vertically mounted bifacial PV modules and crops concerning shortwave solar radiation. The primary objective is to develop a comprehensive solar radiation model that elucidates the contributions of downwelling and upwelling solar radiation on the front and rear faces of PV modules and the ground, emphasizing dual-use applications. A major challenge lies in the spatial variability of incident and reflected solar radiation. Therefore, it's essential to consider shading geometry, the hemispherical distribution of downwelling radiance, and the temporal profile of albedo across different scales, from intra-daily to seasonal variations. Vertical PV modules are particularly sensitive to reflected radiation from crops, soil, or other PV modules, necessitating precise quantification of these components. To achieve this, we propose integrating a systematic Cell to System gain and loss methodology, adapted from Cell to Module analysis, with a matrix-based Raytracing approach (RADIANCE). This approach separates the sky's angular energy distribution from the geometry. We address the limitation of fixed surface properties in this method by binning albedo values and interpolating to capture temporal variations in ground properties. This results in an efficient transposition method compared to classic Raytracing techniques. This model describes solar radiation in the vertical plane of PV modules, accounting for incident and reflected beam and diffuse components for each face, both at minute intervals and cumulatively on a monthly scale. Validation through in-situ pyranometer measurements at minute resolution, which were quality-checked, demonstrates the model's accuracy over a period of six months. An impact transfer analysis between albedo and production is underway to discuss the temporal variability impacts.
