Modeling of Solar Radiation Using Python Programming and Comparison with Experimental Data

Abstract

This paper presents a comprehensive numerical modeling and validation of solar radiation intensity at the Earth’s surface using three established clear-sky models: ASHRAE 2001, Hottel (1976), and ASHRAE 2009. The purpose is to evaluate their accuracy over the course of a year, based on simulation results computed using Python and MATLAB environments. Each model is applied to compute direct and diffuse solar radiation as a function of the day of the year and the tilt angle of the receiving surface. The computed values are graphically compared with experimental data to assess each model’s relevance and limitations. Key performance metrics (mean bias error, root mean square error, etc.) are calculated to quantify model accuracy, and the results indicate that the ASHRAE 2001 model shows the closest agreement with measurements among the models tested. This study contributes to the optimization of solar energy system design and model selection for specific climatic conditions, and provides an open-source Python implementation for reproducibility.