Uncertainty of Climate Specific Energy Rating (CSER) of PV Modules in Accordance With IEC 61853

Abstract

The energy rating of PV modules is related to its energy yield performance in specific reference climates. In contrast to the nominal output power, which is related to the standard test conditions (STC), the energy rating considers the interaction of the PV module characteristics with the reference climate conditions. The following PV module parameters affect the amount of produced energy: (a) temperature behaviour, (b) low irradiance behaviour, (c) spectral responsivity and (d) angular responsivity. To compare the energy yield performances of PV modules, the standard series IEC 61853 defines a specific metric, which describes the energy yield performance of a PV module by a single parameter, the Climate Specific Energy Rating (CSER). Whereas recent studies have focused on the harmonization of CSER calculation methods, our study provides a methodology for the calculation of the expanded CSER uncertainty (k = 2). As inputs, we use the measurement uncertainties of PV module parameters, stated by TÜV Rheinland test laboratory. For the six tabulated reference climates of IEC 61853, our work has shown that a CSER uncertainty in the range of ±2%–±2.3% can be achieved. The main contribution in the range of 80% is related to the uncertainties of output power measurements with solar simulators under variable module temperatures and irradiances (G–T matrix). The following are the uncertainties associated with PV module temperature calculation and the measurement uncertainty of the angular response curve. Both are dependent on the reference climate under consideration. The contributions of uncertainties in connection with spectral responsivity and data processing together appear to be of minor importance.