Characterization of Solar Spectral Irradiance Using the Index of Average Photon Energy for Its Use in the Performance Evaluation of PV Modules

Abstract

A model for characterizing the solar spectral radiation distribution only using APE value as input parameter is proposed. Although the uniqueness of the relationship between these parameters has been previously established there is no expression that allows obtaining the solar spectral curves for each APE value. In this work the APE values for which this uniqueness works have been checked. For this, the cumulative probability distribution function for each spectrum has been estimated. Using a data mining technique, named k-means, all these curves have been clustered in five different groups. In each group a solar spectral cumulative distribution function curve known as centroid has been estimated; this curve is similar to the rest of the curves gathered in the group. The spectra distribution per clusters is quite homogeneous. The centroid of each cluster characterizes all curves in the cluster. For doing the analysis, more than two-hundred-fifty-thousands spectra have been used.