Light scattering at random pyramid textures: Effects beyond geometric optics

The currently highest measured efficiency for both side contacted monocrystalline Silicon solar cells is 25.8%. The external quantum efficiency of these solar cells with random pyramids at the front side differs from results achieved with pure ray optical modeling. As is already known from literature, better agreement can be reached by introducing additional scattering into the modeled system. Within this paper we show that this scattering can be well explained using a Phong-like scatterer. What is more, we show that in the investigated high efficiency solar cells scattering at the rear side is a minor effect although it is often assumed as the origin of scattering. The relevant scattering instead is caused by the random pyramids themselves.