Investigating the Crosslinking, Degradation, and Adhesion Behavior of Photovoltaic Encapsulants Under Thermal Accelerated Aging

IF 2.5 3区工程技术 Q3 ENERGY & FUELS

IEEE Journal of Photovoltaics Pub Date : 2024-12-16 DOI:10.1109/JPHOTOV.2024.3496512

Kuan Liu;David C. Miller;Nick Bosco;Jimmy M. Newkirk;Tomoko Sakamoto;Reinhold H. Dauskardt

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引用次数: 0

Abstract

Degradation of photovoltaic (PV) module encapsulant characteristics that lead to mechanical embrittlement and delamination remains a cause of failure in solar installations. A multiscale reliability model connecting the encapsulant mechanical and fracture properties to the degraded molecular structure and interfacial bonding to adjacent solar cell and glass substrates was previously published. The model, developed primarily for poly(ethylene-co-vinyl acetate) acetate (EVA) encapsulants, remains to be experimentally validated. Determining the degradation and crosslinking kinetics of alternative encapsulants, such as polyolefin elastomer (POE) and EVA/POE/EVA composites (EPE), can generalize the model. In this work, we subject fully cured EVA, POE, and EPE encapsulants to accelerated thermal aging to determine how high temperatures impact reaction kinetics. An increase in gel content (crosslinking) and decrease in crystallinity of the encapsulants under hot-aerobic (90 °C, 22% RH) and hot-anaerobic (90 °C, sealed in N₂ air) aging were observed, even in the absence of UV and crosslinking initiators. Fourier transform infrared spectroscopy (FTIR)-attenuated total reflectance analysis showed insignificant encapsulant degradation, demonstrating the critical role of UV and moisture in accelerating degradation. Adhesion testing performed on coupon-level specimens (cell/encapsulant/glass laminates) showed decreases in adhesion energy, G_c, from 5000 h of hot-dry (90 °C, ∼1% RH) and hot-humid (90 °C, 60% RH) aging. POE coupons demonstrated the best stability, followed by EPE then EVA. For EVA and POE, hot-humid aged coupons experienced a larger decrease in G_c due to enhanced hydrolytic degradation. Hot-dry aging condition demonstrated that thermal degradation of the interface could be significant even if the encapsulant experiences negligible degradation in the absence of UV and elevated humidity.

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来源期刊

IEEE Journal of Photovoltaics ENERGY & FUELS-MATERIALS SCIENCE, MULTIDISCIPLINARY

CiteScore

7.00

自引率

10.00%

发文量

206

期刊介绍： The IEEE Journal of Photovoltaics is a peer-reviewed, archival publication reporting original and significant research results that advance the field of photovoltaics (PV). The PV field is diverse in its science base ranging from semiconductor and PV device physics to optics and the materials sciences. The journal publishes articles that connect this science base to PV science and technology. The intent is to publish original research results that are of primary interest to the photovoltaic specialist. The scope of the IEEE J. Photovoltaics incorporates: fundamentals and new concepts of PV conversion, including those based on nanostructured materials, low-dimensional physics, multiple charge generation, up/down converters, thermophotovoltaics, hot-carrier effects, plasmonics, metamorphic materials, luminescent concentrators, and rectennas; Si-based PV, including new cell designs, crystalline and non-crystalline Si, passivation, characterization and Si crystal growth; polycrystalline, amorphous and crystalline thin-film solar cell materials, including PV structures and solar cells based on II-VI, chalcopyrite, Si and other thin film absorbers; III-V PV materials, heterostructures, multijunction devices and concentrator PV; optics for light trapping, reflection control and concentration; organic PV including polymer, hybrid and dye sensitized solar cells; space PV including cell materials and PV devices, defects and reliability, environmental effects and protective materials; PV modeling and characterization methods; and other aspects of PV, including modules, power conditioning, inverters, balance-of-systems components, monitoring, analyses and simulations, and supporting PV module standards and measurements. Tutorial and review papers on these subjects are also published and occasionally special issues are published to treat particular areas in more depth and breadth.