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• Ultraviolet degradation of encapsulants for photovoltaic modules. • Accelerated indoor UV-aging for photovoltaics devices. • Transmittance of UV degraded polymeric encapsulants. • Indoor UV irradiation of encapsulants related to the Atacama Desert UV conditions. • Raman Spectroscopy for analyzing the degradation of encapsulants in c-Si based PV modules. The performance of photovoltaic modules is highly dependent on the properties of the materials used to build them and is particularly sensitive to the type of encapsulant in the case of harsh outdoor environments. In this study, we compared the effects of ultraviolet (UV) radiation, under laboratory accelerated aging conditions, of four encapsulants: thermoplastic olefin, thermoplastic polyurethane, silicone, and ethylene vinyl acetate. The operation of the indoor ultraviolet chamber, using a mercury/xenon arc lamp as a radiation source, was related to the Atacama Desert ultraviolet conditions to estimate the corresponding time under outdoor conditions. The total indoor experiment time corresponded to 24.7 years of UV-B and 1.34 years UV-A irradiation. Transmittance in the ultraviolet–visible range, together with Raman spectra were analyzed to assess the effect of ultraviolet degradation. The aged encapsulants showed a transmittance reduction between 2% and 5% and a displacement in the ultraviolet cut off to higher wavelengths of around 5 nm. This information was used to compute the potential effect on the photogenerated current density of crystalline silicon photovoltaic modules, which decreased between 1% and 4%. Raman spectroscopy indicated the degradation of the encapsulants' polymer structure as an increment in the fluorescence of the spectra, above 50%, and modifications in the relative intensities of the encapsulant́s active Raman modes. [ABSTRACT FROM AUTHOR]

Photovoltaic modules consisting of one back-contact cell were manufactured by vacuum resin infusion process using glass reinforced epoxy composite as encapsulant where the cells are embedded. Incorporation of three coatings onto the composite surface was studied with the aim to improve the electrical performance stability of the modules under ultraviolet (UV), thermal cycling and damp-heat environmental weathering. Photovoltaic and aging performance were examined through the short-circuit current density values and colour change of the composite. Decrease in the initial photovoltaic performance of the modules was caused by the coating deposition. The highest drop in the initial values was observed for the varnish type coating, showing a decrease of 2.6% in short-circuit current. Regarding the performance stability, the decrease was more pronounced in the damp-heat test, presenting the varnish type coating the minimum loss of 1.4% in short-circuit current and a variation of 87% in b* chromatic parameter after 1000 h exposure at 85 °C and 85% relative humidity. The study concluded that the protective coating should be selected to provide the composite modules with an optimal trade-off between the initial electrical performance and the desired stability, with further research work targeted to improve moisture barrier properties. • Back-contact photovoltaic cells were encapsulated in composite material. • Three coatings to improve the aging performance were tested. • Electrical performance stability was enhanced in a trade-off with initial drop. [ABSTRACT FROM AUTHOR]

Photovoltaic modules were manufactured by vacuum resin infusion process using glass reinforced epoxy composite as encapsulant where the cells are embedded. Incorporation of ultraviolet absorber (UVA) and hindered amine light stabilizer (HALS) additives to the epoxy resin was studied, given their potential to enhance the performance stability of the modules under ultraviolet (UV) radiation exposure. Photovoltaic and aging performance were examined through the evolution of external quantum efficiency (EQE) spectra, short-circuit current values and colour change. Decrease in the initial photovoltaic performance of the modules was observed, as evidenced in the short-circuit losses when additives are incorporated. Regarding the performance stability, increasing the content of both, UVA and HALS, leaded to improved results with lower short-circuit current loss and yellowness observed due to UV radiation. The most stable module, with cells embedded in 1% UVA and 1% HALS containing composite, showed a 2.8% short-circuit current loss after an UV exposure of 15.4 KWh/m2. UV protection enhancement was obtained in trade-off with initial photovoltaic performance, which should be considered when defining the additives and the amount to be used. • Photovoltaic (PV) modules were manufactured with fiber reinforced epoxy composite. • The composite was modified with ultraviolet (UV) additives. • Enhanced UV stability was observed in a trade-off with initial PV performance. [ABSTRACT FROM AUTHOR]