Characterizing Bifacial Modules in Variable Operating Conditions

There is increasing interest in the crystalline Si bifacial PV module market due to the opportunity for increased performance in comparison to traditional PV modules because both sides absorb solar radiation. Draft standard IEC TS 609041-2 (Measurement of current-voltage characteristics of bifacial PV devices) describes measurement methods and also sets limits on permissible deviations of operating conditions, e.g. irradiance non-uniformity. The objective of this work is to evaluate rear side irradiance non-uniformity when employing this standard in natural sunlight. This work will also serve to ensure correct measurement of module operating conditions in long-term outdoor testing where conditions will be highly variable, but nevertheless must be accounted for in energy yield or rating calculations. The albedo is also studied for a ground covering white stones under evaluation for use in long term monitoring.