Ana Pérez-Burgos

Analysis of solar direct irradiance models under clear-skies: Evaluation of the improvements for locally adapted models

Direct solar irradiance has to be determined for the design of many energy applications such as photovoltaic systems and concentration systems, and the generation of solar potential maps for energy use. Knowledge of the accurate values of radiation components in a local area will allow optimal sizing of solar energy conversion systems. The estimated values of direct solar irradiance from models are still necessary at those sites where no measurements are available. In this work, different models used for the estimation of the direct component of solar irradiance are analyzed. First, an evaluation of the performance of eight existing original models was performed from which three were selected. Second, the selected models were calibrated to adapt them to our studied geographical area, which is the important aspect of this work, and an assessment of performance improvements for locally adapted models is reported. Experimental data consisted of hourly horizontal global, direct, and diffuse solar irradiance v...

Retrieval of monthly average hourly values of direct and diffuse solar irradiance from measurements of global radiation in Spain

An exhaustive evaluation of the performance of decomposition models to estimate direct and diffuse components from the global horizontal solar irradiance has been carried out in this work. The main objective of this work has been to compare the model performance for two different time bases, hourly and monthly average hourly bases. An extensive database of horizontal solar irradiance from nine locations in Spain was used for the study. The data span through January 1980 to December 2012 of hourly solar irradiance for the nine locations and thus indicate a cumulative year sum of 132 years. This study first investigated the decomposition of the hourly horizontal irradiance into hourly direct and diffuse components using six decomposition models widely referenced in the bibliography. In the hourly decomposition investigation, it was observed that there are no significant differences between the six models for each specific location. Nevertheless, the performance of each of the models was strongly dependent o...