Lower absorption, lower refractive index, and tunable resistance are three advantages of amorphous silicon oxide containing nanocrystalline silicon grains nc-SiOx compared to microcrystalline silicon c-Si, when used as a p-type layer in c-Si thin-film solar cells. We show that p-nc-SiOx with its particular nanostructure increases c-Si cell efficiency by reducing reflection and parasitic absorption losses depending on the roughness of the front electrode. Furthermore, we demonstrate that the p-nc-SiOx reduces the detrimental effects of the roughness on the electrical characteristics, and significantly increases c-Si and Micromorph cell efficiency on substrates until now considered too rough for thin-film silicon solar cells.