An optical comparison of silicone and EVA encapsulants for conventional silicon PV modules: A ray-tracing study

Ray-trace simulation is used to quantify the optical losses of photovoltaic modules containing silicon cells. The simulations show that when the module´s encapsulant is silicone rather than ethylene vinyl acetate (EVA), the module´s short-circuit current density under the AM1-5g spectrum is 0.7-1.1% higher for screen-printed multi-cSi cells, 0.5-1.2% higher for screen-printed mono-cSi cells, and 1.0-1.6% higher for high-efficiency rear-contact cells, depending on the type of silicone. This increase is primarily due to the transmission of short-wavelength light (<420 nm) and is therefore greatest when used with low UV-absorbing glass and cells of a high IQE at short wavelength. We also quantify absorption in the glass, EVA and silicone at longer wavelengths and describe the influence of an encapsulant´s refractive index on escape losses.