Mitigation of UV‐Induced Degradation in Lightweight SHJ Solar Modules via a UV‐Downshifting Encapsulation Strategy

ABSTRACT Lightweight photovoltaic (PV) applications are pivotal for expanding the adoption of solar energy, enabling new installation scenarios and contributing significantly to the renewable energy capacity. However, degradation due to ultraviolet (UV) radiation is a critical concern for silicon heterojunction (SHJ) solar modules, particularly lightweight solar module configurations, where flexible polymer‐based front sheets may provide reduced shielding against UV radiation. In this study, we present a comprehensive investigation of the UV‐induced degradation (UVID) behavior of lightweight SHJ solar modules utilizing encapsulants with different UV‐transmission: UV‐blocking, UV‐transmitting, and UV‐downshifting. After indoor UV exposure of 120 kWh/m 2 , equivalent to 30 months of outdoor exposure in Jülich, Germany, solar modules incorporating these encapsulants exhibited relative efficiency losses of 2.17%, 9.25%, and 6.15%, respectively. The decrease in efficiency was mainly attributed to a reduction in the fill factor ( FF ) of the solar modules, accompanied by a diminished pseudo fill factor (p FF ). Based on detailed FF and p FF loss analyses, we found that p FF loss was the major cause of FF loss, which is attributed to the deterioration of the passivation properties due to UV radiation. Additionally, the influence of series resistance ( R s )‐related FF losses increased, which is attributed to the deterioration of the interconnection foil rather than the UV radiation itself. Additionally, while downshifting (DS) encapsulants helped mitigate UV damage, we observed a diminished DS effect in lightweight configurations, potentially due to photooxidation. Utilization efficiency of DS decreases from around 34% to 21% after 120 kWh/m 2 of UV exposure. Therefore, a novel encapsulation architecture combining UV‐downshifting and UV‐blocking encapsulants was proposed to ensure the UV utilization and stability of lightweight SHJ solar modules. Solar modules featuring this innovative dual‐layer structure preserved over 98% of their initial performance after UV exposure, demonstrating a promising new approach for enhancing UV stability. The comprehensive investigation provides substantial insights into the degradation mechanism of lightweight SHJ solar modules under UV exposure and offers practical strategies in the progress of improving their durability and performance.