Modeling the surface energy balance of a vegetated solar farm

In response to global climate change, photovoltaic (PV) power plants have been rapidly deployed over the past decade in order to reduce greenhouse gas emissions in electricity production. This massive deployment of large-scale solar parks in rural areas raises questions about the modifications in micrometeorology they cause in contrast to conventional rural land surfaces. This calls for physically based land surface models able to represent the specific land-atmosphere interactions induced by solar parks within weather and climate models. In these models, land surface schemes often neglect the alterations in radiative transfer, surface energy balance, and near-surface turbulence caused by solar panels, potentially leading to biases in weather and climate simulations over regions with large-scale PV power plants.

In this contribution, we present PV-LAND, a photovoltaic land surface model developed as an extension of the Interactions between Soil, Biosphere, and Atmosphere (ISBA) scheme, specifically designed to represent the surface energy balance of a coupled soil-vegetation-PV-atmosphere system. The solar park is represented as a periodic array of panel rows over a vegetated surface, and the surface energy balance is resolved using a nodal approach that explicitly describes the front and back surfaces of PV modules, the photovoltaic cell, the underlying vegetated or bare ground, and the air layers within and above the PV canopy. Shortwave and longwave radiative exchanges account for panel shadowing and multiple reflections between panels and the ground, while turbulent exchanges of momentum, heat, and moisture are computed using parameterizations adapted to the specific geometry and aerodynamic properties of PV canopies, as well as to the wind direction relative to the panel rows.

The model has been run in offline mode over an extensive solar park in southwestern France, where flux measurements (radiative, momentum, heat, and water vapor) have been collected for several years. The PV-LAND performances will be presented at the conference, with a focus on the model's ability to represent the surface energy balance and the surface temperatures.