Influence of spectrum mismatch on the standard measurement and outdoor field test for silicon heterojunction solar modules with photon energy tailorable encapsulants

• Published in: Solar energy 2025-01, Vol.286, Article 113157
• Main Authors: Zhang, Chao, Fan, Hualong, Wang, Siping, Wang, Qiang, Zhang, Lei, Li, Hang, Xiang, Chen, Mao, Lizhong, Xia, Zhengyue, Jiang, Fangdan, Xing, Guoqiang, Meng, Xiajie, Yu, Jian
• Format: Article
• Language: English
• Subjects: Outdoor field test; Photovoltaics; PV module energy yield; Spectrum mismatch; UV-downshifting
• ISSN: 0038-092X
• DOI: 10.1016/j.solener.2024.113157

•The UV-downshifting modules exhibit a 1.41% increase in STC power output and offer additional spectral advantages,•The UV-downshifting modules achieve an overall specific yield (SY) gain of 0.51% in outdoor testing compared to UV-cutoff modules.•The study identifies power deviations caused by spectral mismatch in both types of HJT modules and presents corresponding solutions to mitigate these effects. Silicon heterojunction (HJT) photovoltaic module is sensitive to UV irradiation, which makes UV-down shifting films and UV-cutoff films widely used during module encapsulation. However, this method leads to significant variations in Spectral Responsivity (SR) within the UV spectrum band. To evaluate the difference of the two different encapsulants, the modules encapsulated with UV-downshifting and UV-cutoff technologies were prepared from identical cells and subjected to controlled outdoor field testing. A deviation in power output was detected in the UV-downshifting modules. In response, solar simulator filters were modified to generate spectra with varying UV intensities, and the SR of both module types was subsequently analyzed. The spectral mismatch encountered during Standard Test Conditions (STC) power testing was theoretically calculated and experimentally confirmed, showing a maximum deviation of 1.15%. By maintaining consistent encapsulation films for both reference modules and tested modules, spectral mismatch during testing can be effectively mitigated. After correcting the STC power of the UV-downshifting module, a specific yield (SY) gain of 0.51% was achieved for the UV-downshifting module compared to the UV-cutoff module during outdoor testing. This study provides empirical evidence on the performance of UV-downshifting and UV-cutoff modules in outdoor conditions, and addresses spectral mismatch challenges between the STC measurement and outdoor application.