SPLTRAK Abstract Submission
Glass-glass PV modules: Characterization of chemical and mechanical degradation
Laura Spinella1, Sona Ulicna2, Archana Sinha2, Dana B. Sulas-Kern1, Michael Owen-Bellini1, Steve Johnston1, Laura T. Schelhas1
1National Renewable Energy Laboratory (NREL), Golden, CO, United States
/2SLAC National Accelerator Laboratory, Menlo Park, CA, United States

Glass-glass (G/G) photovoltaic modules are quickly rising in popularity, but the durability of modern G/G packaging has not yet been established. In this work, we examine the interfacial degradation modes in G/G modules under damp heat (DH) with and without bias voltage, comparing emerging polyolefin elastomers (POE) and industry-standard poly(ethylene-co-vinyl acetate) (EVA) encapsulants. The transport of ionic species at cell/encapsulant interface is investigated, demonstrating that the POE used in this study limits both sodium and silver ion migration compared with the EVA. Changes to the chemical structures of the encapsulants at the cell/encapsulant interfaces demonstrate both POE and EVA are more susceptible to degrade in modules with transparent backsheet than in the G/G configuration. While the POE structure was shown to degrade, this degradation did not appear to hamper its ability to limit ion migration. Adhesion testing revealed that the POE and EVA had comparable critical debond energies after the DH exposures regardless of applied bias polarities. The results of this study indicate that the interfacial degradation mechanisms of G/G appear to be similar to that of conventional glass/backsheet modules. For emerging materials, our results demonstrate that POE offers advantages over EVA, but that transparent backsheets may accelerate encapsulant degradation due to increased moisture ingress. This indicates that G/G may have some advantage over G/TB.