Performance and life prediction model for photovoltaic modules: Effect of encapsulant constitutive behavior

An encapsulant in a Photovoltiac (PV) module is a polymer used for binding all the components together. It also provides protection of cells and interconnects from moisture, foreign impurities and mechanical damage. In addition to this, the encapsulant must possess certain desirable characteristics such as low cost, high transmittance of light, good thermal conduction and long operating range. The provision of such properties makes it a vital component on which the performance of a PV module depends. Currently, the PV industry is dominated with Ethylene-Vinyl Acetate (EVA) as an encapsulant, mostly due to its low cost. Other polymers such as polydimethylsiloxane (PDMS), polyvinyl butyral (PVB), thermoplastic polyurethane (TPU) and Ionomer have gained interest and are being tested for better encapsulation of PV modules. The current work deals with the comparison of the mentioned encapsulants and selecting the optimum one based on its properties such as light transmittance, UV durability, electrical insulation, water vapor transmission rate and cost. The structural life of PV module is also compared by using these encapsulants. For this purpose, previously developed structural and thermal models are coupled with electrical and life-prediction models to determine efficiency and life of PV module for each encapsulant case. Life prediction of PV module encapsulant is based on a year's data of Jeddah, Saudi Arabia where the interconnect crack initiation defines failure. Under these assumptions, a detailed structural analysis has been carried out. Finally, the results of simulation combined with the other outcomes of literature are used in a decision matrix to give Ionomer to be an optimum encapsulant for PV module.