The light propagation in multiscale textured thin film silicon solar cells is studied experimentally and numerically. The short circuit current and energy conversion efficiency of multiscale textured amorphous silicon thin film solar cells are increased compared to nanoscale textured substrates. A gain of the short circuit current of 1.3 mA/cm(2) is achieved for the multiscale textured solar cell, resulting in short circuit current densities of 16.8 mA/cm(2) and energy conversion efficiency of 10.7%. The light propagation in the solar cells is determined by Finite Difference Time Domain simulations in three dimensions using realistic interface morphologies. The realistic interface morphologies of solar cells are calculated by 3D algorithms. The optical simulations reveal that the interface morphology of the back reflector of the multiscale textured solar cell has a distinct influence on the short circuit current and quantum efficiency. By tuning the optical losses of the metal back reflector, the short circuit current can be increased beyond 18 mA/cm(2). (C) 2015 Elsevier B.V. All rights reserved.