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M Knausz, G Oreski, G Eder, Y Voronko, B. Duscher, T. Koch, G. Pinter, K Berger:
"Degradation of photovoltaic backsheets: Comparison of the aging induced changes on module and component level";
Journal of Applied Polymer Science, 132 (2015), 42093; 1 - 8.

In reliability testing of components for PV modules an always remaining question is about material (in)compatibilities
and synergistic effects and thus, how results of singly tested materials correlate with materials aged within PV modules. Testing of single
materials would simplify sample preparation, reduce costs and offer more testing options. Therefore the main objective of this
study was to compare the aging behavior of single backsheets with that of backsheets incorporated within PV modules. Four different
types of backsheets were chosen, all of them comprising of polyethylene terephthalate (PET) core layers, but differing outer protection
layers. Test modules using identical components, varying only in the type of backsheet used were produced and damp heat aged
(85 C/85% RH 2000 h). The results revealed no influence of the PV module lamination on the thermal characteristics of the polymeric
backsheets. Even after DH aging, differences between single and module laminated backsheets were negligible. Degradation
effects of PET could be detected for all aged sheets by thermal analysis and were confirmed by tensile tests and rheological measurements.
Thus, it can be stated that testing of single PET based backsheets under DH aging conditions is a practicable way to investigate
the applicability of a new backsheet.

ageing; degradation; differential scanning calorimetry; mechanical properties; thermal properties

http://dx.doi.org/10.1002/APP.42093