Rear‐side spectral irradiance at 1 sun and application to bifacial module power rating
C. Monokroussos, Qi Gao, Xiaoyu Zhang, Eleanor S. Lee, Yihong Wang, Chris B. Zou, L. Rimmelspacher, Johanna Bonilla Castro, M. Schweiger, Werner Herrmann
Abstract
Abstract The air mass 1.5 global (AM1.5G) reference spectral irradiance distribution is defined in the international standard IEC 60904‐3, accounts for the direct, diffuse, and albedo components directing 1000 W/m 2 (1 sun) of global irradiance at a photovoltaic (PV) module's front side. Bifacial PV modules, however, receive an additional irradiance contribution from the rear side, which is not accounted for in the reference irradiance. This work strives to shed light on the amount of expected light that arrives on the rear side of a PV module, when the front‐side irradiance and ambient conditions match the conditions used for the calculation of AM1.5G. For this purpose, an optical model was developed to simulate the rear‐side spectral irradiance of PV modules, whose validity was verified by outdoor measurements. The results show that the average rear‐side irradiance at a set of conditions as defined in IEC 60904‐3 lies in the range of 130 to 150 W/m 2 . The results of this work lay the foundation to define the bifacial Standard Test Conditions (BSTC), which can be used to support the technical specification IEC TS 60904‐1‐2 and international standard IEC 60904‐3 and establish supplementary requirements for the power rating and label verification of bifacial PV modules.