Comparison of Bifacial Module Measurement Methods with Optically Optimized Bifacial Modules

We characterize four types of bifacial modules with three different methods that have been proposed by the community. One method approximates rear irradiance with increased front side irradiance. The other two utilize light directly radiating on the rear side of the module. We describe the setup, the calibration, and the resulting errors inherent to each method. Comparing the results, we find that current scales Linearly with additional irradiance on either the front or rear of the module and is in good agreement between all of the methods. However, characterization methods with light incident on the rear of the module results in higher power, suggesting asymmetric front and rear power scaling at low light conditions for high efficiency bifacial modules.