Translation of outdoor tandem PV module I–V measurements to a STC power rating

Abstract

AbstractThe procedures for the power rating of tandem‐cell‐based concentrator photovoltaic (CPV) modules defined in the international standard IEC 62670‐3 are adapted to the requirements of tandem‐cell‐based flat plate PV modules. The adjusted procedure describes how to translate outdoor measured PV current–voltage characteristics to standard test conditions (STC): 1000 W/m, 25°C cell temperature, AM1.5g spectral conditions. In this work, we describe how to obtain all required input parameters: thermal transient measurements to determine the module temperature coefficients, categorizing and filtering the prevailing spectral irradiance conditions using spectral matching ratios, and determining the 25°C module open‐circuit voltage from dark current–voltage curves. Three specimen PV modules (triple‐junction, III‐V on Silicon and III‐V on Germanium) have been measured for several months outdoors on a dual axis tracking unit at Fraunhofer ISE in Freiburg. In this work, we demonstrate that the CPV module power rating procedures in IEC 62670‐3 are also—in a modified form—to be recommended for the outdoor rating of tandem‐cell‐based flat plate PV modules.