Preliminary evaluation of a new tool for modeling all-sky spectral solar radiation on tilted orientations for agrivoltaic applications

Accurate solar resource modeling is critical for technical and economic feasibility studies of solar related projects. More precisely, accurate transposition models, which translate horizontal irradiances to tilted ones in the Plane of Array, are crucial notably for agrivoltaic applications to determine the light sharing between the crops and the photovoltaic modules. While conventional transposition models are fast and reliable, their limited spectral characterization of solar radiation can introduce significant uncertainties.This study presents the preliminary evaluation of a new sky radiance model aimed at the spectral characterization of solar radiation as a function of the module position under all-sky conditions. The evaluation utilizes ground measurements collected from June 2019 to June 2020 at the Plataforma Solar de Almería (PSA), focusing on global and diffuse tilted irradiances (GTI and DTI, respectively). These observations are supplemented with reanalysis data to provide the necessary inputs to the model. A distinction is made between clear-sky and cloudy conditions to ensure a comprehensive assessment of the model's performance across varying atmospheric scenarios and to mitigate discrepancies between observed and modeled inputs.The model demonstrates satisfactory performances, achieving results comparable to established models from the literature. Mean biases for GTI estimates are below 3% under both clear and cloudy conditions, with root mean square deviations (RMSD) ranging from 1% in clear-sky conditions to 11% under cloudy skies. For DTI estimates, the model exhibits slightly higher uncertainties, with biases between -2% and +4% and RMSD values ranging from 8% to 17%.