Our monocrystalline thin-film solar cells grown on textured porous silicon are almost planar on one side and are textured with random, inverted pyramids on the other side. We compare solar cells illuminated through the textured side with solar cells that are illuminated through the almost planar side. Two-dimensional numerical modeling of the measured internal quantum efficiency shows that the textured front side increases the collection efficiency of the base. This effect, together with the reduction of the front surface reflectance, makes a textured front surface advantageous over a planar front surface.