Optical Characterization and Loss Simulation of Encapsulation Materials and Back Sheets for PERC+ Solar Modules

In a PV module the J
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is impacted by multiple factors such as geometrical effects, reflection on interfaces and absorption properties of the module components. A major contributer to parasitic absorption are encapsulation materials which are based on different polymers (ethylene-vinyl acetates and polyolefins) with different UV-properties (UV-absorbing and UV-transparent). This raises the question which material to use and how to find the optimal material for a given solar cell. This can be done with simulations of cell-to-module (CTM) losses. However the optical properties of those encapsulating polymers need to be known. In this work multiple encapsulants are characterized in a wavelength range from 300 to 1200 nm to determine their optical constants. Those constants are used for ray-tracing simulations of PERC+ silicon half cell modules with glass or backsheet rear sides to identify losses in J
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due to absorption in those materials. To gain further information about optical CTM loss mechanisms of these encapsulation materials different rear sides are simulated. As a main conclusion it is shown that encapsulants and rear sides can be optimized independently to maximize the module J
sc.
This can reduce the number of required experiments for a number of L encapsulants and M rear sides from L x M to L + M - 1 when optimizing the optical properties of a solar module.