Title:	Raman Spectroscopic Determination of the Degree of Encapsulant Crosslinking in PV Modules
Author(s):	C. Hirschl, M. Biebl-Rydlo, W. Mühleisen, L. Neumaier, G.C. Eder, B.S. Chernev, M. Kraft
Keywords:	Raman Spectoscopy, Ethylene Vinylacetate, Degree of Cross-Linking, Photovoltaic (PV)
Topic:	COMPONENTS FOR PV SYSTEMS
Subtopic:	PV Modules
Event:	28th European Photovoltaic Solar Energy Conference and Exhibition
Session:	4AV.4.2
Pages:	3020 - 3025
ISBN:	3-936338-33-7
Paper DOI:	10.4229/28thEUPVSEC2013-4AV.4.2
Price:	0,00 EUR
Document(s):	paper, poster

Abstract/Summary:

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With the increasing use of PV installations and the highly competitive situation on the PV module market, the modules’ reliability and long-term performance over projected operational lifetimes of 25+ years become key factors. One component known to have a vital impact on the long-term characteristics, and hence of particular interest here, is the polymeric solar cell encapsulant. Presently, the prevalent material of choice for this is elastomeric ethylene vinyl acetate (EVA). While several analytical methods to evaluate the curing, i.e. crosslinking, state of EVA exist, an industrially applicable in-line quality control method is still lacking. The approach explored in this work uses Raman spectroscopy. In contrast to most other methods, Raman spectroscopy allows a contact-free analysis through the front glass, in-line and in real time in the manufacturing line. The Raman spectra of differently crosslinked EVA samples and modules show subtle but characteristic spectral differences in the CH-stretching vibration region (3.000 – 2.800 cm-1) that correlate unambiguously and reliably to the state of encapsulant crosslinking.