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.