Table of Contents
ISRN Renewable Energy
Volume 2012, Article ID 459731, 5 pages
Research Article

Impact of Permeation Properties and Backsheet-Encapsulant Interactions on the Reliability of PV Modules

Fraunhofer-Institut für Solare Energiesysteme ISE, 79110 Freiburg, Germany

Received 27 April 2012; Accepted 9 July 2012

Academic Editors: F. E. Little, Y. Matsumoto, and S. Senthilarasu

Copyright © 2012 Cornelia Peike et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The reliability of photovoltaic modules is highly influenced by the material properties of the backsheet and encapsulation material. Currently, little attention is paid to the permeation properties of the back-sheet material or to its impact on encapsulation degradation and module reliability. We investigated the interaction of different types of solar encapsulation and back-sheet materials. Therefore, various laminates were made to examine the environmental impact on such materials during the aging processes. One focus of our study lies in oxygen and water vapor permeability of the back-sheet materials. The encapsulants used were an ethylene vinyl acetate (EVA), a TPSE (thermoplastic silicone elastomer), an ionomer, and a PVB (polyvinyl butyral). Back-sheet materials were a TPT (Tedlar-PET-Tedlar) foil, a polyamide (PA) sheet and a polyethylene terephthalate (PET) composite film. Raman spectroscopic and FT-IR/vis-reflectance measurements were carried out before and after different accelerated aging procedures. The water vapor and oxygen permeation properties were measured. A clear correlation between the permeation properties and the observed aging behavior was found. The degradation, especially of the encapsulant, resulted in increased fluorescence background in the Raman spectra. It could be shown that the encapsulation-cell-backsheet system should be optimized in order to minimize the stress on the PV-module components.