Filtering Procedures for Reliable Outdoor Temperature Coefficients in Different Photovoltaic Technologies

Abstract

Power temperature coefficients خ´ (TCo) measured indoor at standard test conditions (STC) (as given on products datasheet) always present a negative sign; an increase in temperature leads to a reduced power output. Interestingly, the magnitude of the TCo is not always confirmed outdoor with significant differences between technologies with even change in signs in some cases (e.g., aSi). It is important to investigate if the reported outdoor behavior is a true effect or if it is the result of a choice of nonhomogeneous sets of data (e.g., either irradiance sensor or modules shaded). In this work, the importance of filtering procedures is discussed in order to work with a reliable set of data and to establish a method that allows comparison with indoor data.