Electrical characterization method for bifacial photovoltaic modules

Abstract

We present a method to characterize bifacial photovoltaic (PV) modules for simultaneous front and rear side illumination (i.e., bifacial illumination). The method uses standard monofacial (i.e., single-sided) indoor current–voltage measurements on the front and rear sides of the bifacial module, while covering the other side with a non-reflecting black cover. To define the performance under bifacial illumination, new bifacial parameters (short-circuit current, open-circuit voltage, fill factor and efficiency) are calculated using a one-diode model of the PV module. Assuming linear current response of PV modules for different illuminations, the method numerically simulates the performance of bifacial PV modules for various combinations of front and rear side irradiances. The method is useful in predicting the behavior of the bifacial PV module under bifacial illumination, without actually measuring the module under these conditions. Using a silicon wafer based bifacial PV module, we demonstrate experimentally that the method can predict the performance to within 1% variation with actual measurements.