Estimation of Solar Irradiance for the Maltese Islands

Solar energy is a promising renewable resource. Solar radiation modelling is essential for optimising its potential. This study replicates an existing model, namely, SOLAR, originally implemented in Fortran, and adapts it using MATLAB. The model estimates the hourly average solar irradiance under all-sky conditions, incorporating two cloud cover estimation methods, i.e., sub-models, labelled as Model 1, based on the daily total solar flux, and Model 2, which uses daily total sunshine hours. The new implementation of the model was evaluated using an extensive data set collected at two monitoring sites in Malta. Results indicate that both sub-models perform well under moderate to high solar irradiance conditions, in keeping with findings of previous studies. Higher correlation between the modelled and corresponding measurements were observed for clearer conditions, suggesting better model performance when the cloud cover is minimal. However, the discrepancy increased for low solar irradiance, indicating challenges when it comes to cloud cover estimation. In this study, modelled and observed data correlated better as compared to previous studies, implying that the model suits better the Mediterranean conditions. This study demonstrates that a straightforward, yet effective solar modelling approach can be successfully adapted to different geographical contexts with minimal modifications. The findings highlight the model’s reliability for solar energy applications in regions with varying atmospheric conditions, making it a valuable tool for solar radiation forecasting and energy assessments where high computational complexity cannot be afforded.