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M Knausz, G Oreski, M Schmidt, P Guttmann, K Berger, Y Voronko, G Eder, T. Koch, G. Pinter:
"Thermal expansion behavior of solar cell encapsulation materials";
Polymer Testing, 44 (2015), 160 - 167.

The object of this paper is to determine the thermal expansion behavior of nine different
encapsulants in order to identify possible deficiencies in production processes and allow
for the optimization of the process parameters. High dimensional stability of the encapsulant
is of great importance in photovoltaic (PV) module production to avoid problems
during lamination and/or in application. For this purpose, the samples were heated twice
in a thermo-mechanical analyzer (TMA) in tensile mode, and the coefficient of thermal
expansion (CTE) over temperature was evaluated. To get additional information about
transition temperatures of the encapsulants, differential scanning calorimetry (DSC)
measurements were made. The TMA results for most samples showed anisotropic behavior
which was eliminated after the first heating run. Three samples showed shrinkage with
subsequent increased thermal expansion as well as anisotropic behavior. It could be shown
that knowing the thermal expansion behavior of the solar cell encapsulants is highly
relevant for the PV module lamination process, and Thermo-Mechanical Analysis proved to
be a suitable method to evaluate and also for quality control of solar cell encapsulation
films.

PV encapsulants; thermal expansion; thermal stresses

http://dx.doi.org/10.1016/j.polymertesting.2015.04.009