Solar radiation on inclined surfaces: Corrections and benchmarks

Predicting solar radiation on inclined surfaces is a critical task for photovoltaic energy systems design, simulation and performance evaluation. Many transposition models have been proposed in the literature; and there are abundant evaluation studies. However, these models are sometimes used incorrectly. Moreover, these errors tend to propagate through the literature. This paper aims to identify and correct some errors in the literature. It also provides a benchmark on transposition model accuracies. Twenty-six models are described using a consistent nomenclature. Model performance is ranked and pairwise accuracies are evaluated with one year of solar irradiance measurements from four locations. Although no universal model is found in this study, some are recommended. The paper comes with computer code and a small portion of experimental data.