TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Method: The method of producing a solar cell, further comprises: wet chemical etching the substrate so as to texture the substrate prior to forming a first thin-film structure; forming the conductive electrodes over the transparent conductor; forming an amorphous intrinsic layer on the underside of the substrate such that it is positioned between the underside of the substrate and the doped conductive layer; and forming a diffusion in the metallurgical grade substrate, where the diffusion layer is one of an n-type or p-type. The step of forming the first thin-film structure comprises forming at least one of the first intrinsic layer and the first doped layer as an amorphous silicon layer, to comprise hydrogen atoms dispersed within a silicon layer. The step of forming the bottom conductive contact comprises forming a doped conductive layer of the same polarity as the substrate, on the underside of the substrate and forming a metal layer over the doped conductive layer. The step of forming the top conductive contact comprises forming a transparent conductor over the first doped layer. In the method of producing the solar cell, obtaining a multi-crystalline substrate comprises: slowly solidifying metallurgical silicon melt into a cylinder with large silicon grains and resistivity of 1 Ohm-cm; or obtaining silicon wafers consisting essentially of a p-type metallurgical grade silicon of resistivity of 1 Omega cm; or fabricating multi-crystalline wafers doped with both boron and phosphorus and having p-type polarity. The step of forming the second thin-film structure comprises forming a first doped thin-film over the first thin-film structure, forming an intrinsic thin-film over the first doped thin-film, and forming a second doped thin-film over the intrinsic thin-film, to form a second thin-film p-i-n structure over the first p-i-n structure. The first doped layer is an n-type layer formed over and in contact with the intrinsic layer and forming the second thin-film structure comprises forming a p-type layer over and in contact with the first n-type layer, forming a second intrinsic layer over the p-type layer and forming a second n-type layer. The method of fabricating a solar cell, further comprises forming a second thin-film structure over the first thin-film structure. In the method of fabricating a solar cell: the step of forming a first thin film structure comprises forming a first intrinsic layer over and in contact with the diffusion layer and forming a first doped layer of same conductance of the first type over and in contact with the intrinsic layer; and the step of forming a second thin-film structure over the first thin-film structure comprises forming a thin-film p-i-n junction. EXAMPLE - No suitable example given.