CFD, a radiative model, and a plant model to capture the interactions between solar panels, the atmosphere, the soil, and the plants in agrivoltaic configurations.

Currently, our understanding of the impact of agrivoltaic systems on the crops is limited. The presence of panels modifies the micro-climate and therefore the radiative, thermal, and aeraulic exchanges between the crop and its surrounding (S. Edouard, 2022). These modifications can lead to a loss of agricultural production, but also to a crop protection against meteorological events. Crop models, such as DSSAT, are not suitable to study the impact of solar panels on crop growth as spatial and temporal averages in the models hide spatial heterogeneities caused by the panels, and the sub-daily phenomena are not simulated. Computational fluid dynamic (CFD) allows high-fidelity simulations of multi-physics problems on different time and length scales (such as thermal hydraulics in power plants, or the drag of a wind farm). First CFD simulations applied to agrivoltaics have been carried out by (S. Zainaly, 2023), and by (H. J. Wiliams, 2023). Through Joseph Vernier’s PhD thesis, EDF R&D has initiated CFD modeling applied to agrivoltaics.

 

The CFD solver code_saturne simulates the flow over the panels, as well as the radiation, the temperature, and the humidity fields. Moreover, a 2 layers force-restore soil model computes the energy and the water exchanges between the soil and the atmosphere. The effect of the micro-climate on the photosynthesis and the plant stomatal resistance must be considered to accurately predict the plant growth. That is why, the soil-plant-atmosphere continuum model (A. Tuzet, 2003) has been implemented in code_saturne and a simplified study case composed of four solar panels has been built. First simulations of the modifications of the micro-climate by the solar panels and how it impacts the crops are very promising. Indeed, spatial heterogeneities are well simulated for the radiation, and the soil temperature (Figure 1-4), as well as for the wind speed (Figure 5, 6), the plant temperature, the photosynthesis, and the evapotranspiration. Simulations of the impact of shading on the soil water balance reveals that the plant’s energy balance is locally modified in a complex fashion that depends on the agrivoltaic power plant geometry. Water stress is considered, and it interferes with the plant's ability to photosynthesize and to transpire. Thanks to the coupling of code_saturne and the soil-plant-atmosphere continuum model, the plant state is simulated along the day for different weather conditions and agrivoltaic configurations. This is a first step towards a deeper understanding of the physical interactions within a photovoltaic system.