A photovoltaic module is a multi-stack system, compound of a semiconductor generally made of silicon, protected on is upper face a polymer encapsulant and a glass layer. The most usually employed polymer is ethylene-vinyl acetate (EVA) because of its moderate cost and its ease of implementation. However, an extended exposure on UV cause a loss of adhesion and a reduction of the optical transmission (phenomenon of yellowing). Although new formulations of EVA were developed, incorporating antioxidants and UV absorbers, the degradation of the optical properties of a module (via encapsulant and anti-reflective coat of the cell) is nowadays the main cause of the decrease of the performance and the efficiency of the photovoltaic system with time. The goal of this work is to evaluate the behavior of the functional optical properties (transmission, reflection) of a standard formulation of EVA during accelerated ageing under UV. An important temperature of lamination (155 °C) seems to be optimal for the optical properties evolution but not for physico-chemical one.
photovoltaic, ageing, EVA, optical transmission
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