Outdoor Performance of Bifacial Modules by Measurements and Modelling

We present the outline of a model that calculates the outdoor performance of a bifacial module including optical, electrical and thermal aspects. The IV curve for the total module power output is obtained by scaling or weighting the 2-diode parameters of front and rear standard test conditions (STC) module IV curves with the calculated front and rear irradiance. Validation and verification of the electrical model are given through simulations and measurements. Annual yield gain predictions based on measured characteristics of bifacial modules are presented and discussed for vertical,east-west bifacial modules relative to south-facing tilted monofacial modules. For a module with a bifaciality factor of 92% in a location like Amsterdam, this predicted annual yield gain is in the order of 10% at albedo 0.2 and 30% at albedo 0.5.