ABSTRACT Encapsulants are critical in ensuring long photovoltaic (PV) module lifetimes. Recent innovations in encapsulant formulation are modifying the encapsulant landscape with the promises of techno‐economic advantages: cell technology‐specific materials, the use of multilayer encapsulants, and the use of UV downshifting films (UV‐DS). In this work, we present one of the first complete material and module‐level performance and reliability testing of one of the latest generations of commercial coextruded EVA/POE/EVA (EPE) encapsulant containing an organic downshifting luminescent chromophore. We demonstrate that the encapsulant maintains excellent optical, mechanical, and adhesion properties at the initial time and after aging. We investigate the diffusion of the additives occurring between the solar cells upon thermal treatment, revealing a potential competition between luminescent and UV‐cut additives. Silicon heterojunction (SHJ) mini‐modules pass three times the IEC61215–1:2021 damp heat and thermal cycling sequences with minimal performance losses of 1.3% and 2.0%, respectively. Commercial‐sized modules fabricated with UV‐DS encapsulant show a power gain of 1.75% over the conventional UV‐cut‐based modules. We demonstrate a high spectrum dependence of these results based on the light source used for the measurement. Finally, outdoor monitoring confirms the energy gain and highlights its dependence on the UV content of the on‐site solar spectrum, with a 2.2% energy production gain in the summer that drops to less than 1% in the winter due to lower UVA irradiances.
Babics et al. (2026) studied this question.