4. 1 PV Module Design, Manufacture, Performance and Reliability
Summary / Abstract:
Degradation of polymer components of silicon PV modules, like backsheets (BSs) and encapsulant, is among the major factors affecting performance and lifetime. As the degradation mode depends on the BS composition, module failure analysis requires reliable and field-ready methods for identification of BS structure and degradation state. Recently, we have introduced near-infrared absorption (NIRA) spectroscopy as a highly informative and non-invasive method for field determination of the BS composition . The NIRA-based discrimination between non-fluorinated, polyamide (PA), or polyethylene terephtalate (PET), BSs and multi-layer BSs based on fluoropolymer (FP) airsides and PET core layers is relatively simple. At the same time, identification of various versions of FP/PET-based BSs differing in layer number, thickness and order becomes a complicated task due to a very similar structure of NIRA spectra of such multi-layer BSs. Here, we present an advanced version of our approach and use a combination of multi-spectral Raman mapping and NIRA to develop a method that allows a refined backsheet identification in the field with NIRA alone. The proposed approach includes generation of a library of BS cross-sectional maps produced by Raman microscopy, association of each particular map with the corresponding NIRA spectrum, and a multivariate analysis of NIRA spectra allowing small variances in the NIRA spectra to be detected and related to a particular BS structure. Scientific innovation and relevance.