Non-isothermal Curing Kinetics Model for Lamination of EVA or POE based Double Glass PV Modules
Sprache des Vortragstitels:
Englisch
Original Tagungtitel:
52nd IEEE Photovoltaic Specialists Conference
Sprache des Tagungstitel:
Englisch
Original Kurzfassung:
In this paper, a method to determine the non-isothermal curing kinetics of peroxide crosslinking ethylene vinyl acetate copolymer (EVA) and polyolefin elastomer (POE) encapsulants is presented. The curing kinetics model was derived from dynamic mechanical analysis (DMA) measurements of viscosity changes under isothermal conditions. DMA was performed from 125 to 150°C in 5°C increments. This allowed for calculation of curing rates by numerical differentiation of conversion curves. The non-isothermal curing kinetics were modelled with a temperature dependent Arrhenius rate coefficient and a reaction rate model. To evaluate the accuracy of the model, the initial isothermal DMA data was fitted and a non-isothermal validation routine was performed. The curing model showed a very high accuracy under both conditions. Moreover, the model was used to predict the crosslinking homogeneity in mini PV modules. Therefore, modules were manufactured in a vacuum laminator and temperature was measured at seven different positions. The fastest crosslinking was observed at the bottom glass, which was in direct contact with the heated plate of the laminator. Interestingly, the slowest conversion was observed in the module center and not at the topside glass. Presumably, this was related to the heat flux through the silicone membrane. Furthermore, it was found that a lamination temperature of 150°C was insufficient for curing of POE based mini modules. However, at a temperature of 160°C, POE showed similar conversion rates compared to EVA processed at 150°C.
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