Electrical insulation and thermal expansion behavior studies on ethylene vinyl acetate nano composites for photovoltaic encapsulation

The effectiveness of the inclusion of modified Zinc Oxide nano particle (m-ZNP) on to the poly ethylene vinyl acetate (EVA) matrix is analyzed under this study. EVA/m-ZNP based nanocomposites are formulated with variable concentrations of m-ZNP, 0.05, 0.1, 0.15 and 0.2 phr using solvent casting method. Maintaining good electrical insulation properties for photovoltaic (PV) encapsulation is very important to ensure the functionality of Si-PV modules. Insulation properties namely DC volume and surface resistivity as a function of filler are studied for these laboratory prepared EVA/m-ZNP nanocomposites. Dielectric strength is performed at ambient condition on the nanocomposite film samples as additional evidence of its insulation properties. Thermal based Dimensional stability is another vital property of the encapsulant in PV module to avoid difficulties during production and service. Thermo-mechanical analysis (TMA) is carried out in tension mode to check the coefficient of thermal expansion (CTE) of the EVA/m-ZNP nanocomposites. CTE of the EVA/m-ZNP nanocomposites decreases with inclusion of 0.05 and 0.1 phr of m-ZNP. While, 0.15 and 0.2 phr m-ZNP filler loadings show the increment in CTE. Finally, it can be inferred that 0.1phr m-ZNP loading can be considered as the optimum quantity of nano filler addition which has achieved the desirable level of electrical insulation properties, with reduction in CTE value.