Modeling the incidence angle dependence of photovoltaic modules in PVsyst

For reliable energy yield simulation, it is important to know how irradiance is transmitted through the glass front cover of a photovoltaic module. In this work, Fresnel reflection and Snell´s law are used to create a physical model to determine transmission as a function of incidence angle. The physical model is used to describe glass with and without an anti-reflective coating. An approach for optimizing the ASHRAE incidence angle modifier parameter in PVsyst to match the physical model output is presented and applied to both cases and the impact on energy yield estimates is demonstrated for various geographical locations.