NOVELTY - A solar cell comprises substrate (500) containing doped metallurgical grade silicon; first thin-film structure formed over and in contact with upper side of substrate; second thin-film structure formed over first film; top conductive contact formed above second structure; and bottom conductive contact formed over underside of substrate. The substrate is doped as p-type or n-type, where first structure comprises first intrinsic layer in contact with substrate and first doped layer of opposite polarity of substrate formed in contact with intrinsic layer.    USE - As solar cell (claimed) i.e. solar photovoltaic cells for energy generation.    ADVANTAGE - The solar cells are low cost cells. The silicon substrate can be fabricated without the need to perform gasification of silicon as a result the cost and health and environmental hazards involved in fabricating the silicon are avoided. The substrate thus formed can be used for fabrication of solar cells with efficiency that is comparable and even surpass thin-film solar cells. The solar cell is fabricated by utilizing silicon wafers made of very low cost metallurgical-grade silicon as the substrate. The cells are fabricated by depositing thin films of very small thicknesses (e.g. 10%) compared to conventional thin-film solar cells. Besides reducing the cost of substrate and film material, the structure promises increased conversion efficiency over conventional thin film solar cells i.e. by utilizing metallurgical-grade silicon wafers the fabrication of substrates becomes less hazardous and more environmentally friendly, while also reducing the cost of the substrates. The utilization of metallurgical-grade silicon wafers as the substrate increases the conversion efficiency as compared to thin-film structures formed on glass.    DETAILED DESCRIPTION - A solar cell comprises a substrate (500) containing doped metallurgical grade silicon; a first thin-film structure formed over and in contact with upper side of the substrate; a second thin-film structure formed over the first thin film structure; a top conductive contact formed above the second thin-film structure; and a bottom conductive contact formed over underside of the substrate. The substrate is doped as one of a p-type or n-type, where the first thin-film structure comprises a first intrinsic layer formed over and in contact with the substrate and a first doped layer of opposite polarity of the substrate formed over and in contact with the intrinsic layer. At least one of the first intrinsic layer and the first doped layer comprises an amorphous silicon layer or hydrogen atoms dispersed within a silicon layer. The bottom conductive contact comprises a doped conductive layer of same polarity as the substrate formed over the underside of the substrate and a metal layer formed over the doped conductive layer. The top conductive contact comprises a transparent conductor formed over the first doped layer. The solar cell further comprises at least one of a protective layer and an anti-reflective layer (515) formed over the transparent conductor; an amorphous intrinsic layer formed between the underside of the substrate and the doped conductive layer. The substrate comprises metallurgical grade silicon of purity of three to five nines. The solar cell further comprises a second thin-film structure formed between the thin-film structure and the top conductive contact. The first thin-film structure comprises a first intrinsic layer formed over and in contact with the substrate and a first n-type layer formed over and in contact with the intrinsic layer, where the second thin film structure comprises a p-type layer formed over and in contact with the first n-type layer, a second intrinsic layer formed over the p-type layer and having a higher thickness than the first intrinsic layer, and a second n-type layer. An INDEPENDENT CLAIM is included for fabricating a solar cell involving forming a substrate comprising a metallurgical grade silicon doped to a first type of conductance; forming a diffusion layer on top surface of the substrate such that the diffusion layer has opposite conductance of the first type; and forming a first thin-film structure over and in contact with the diffusion layer.    DESCRIPTION OF DRAWING(S) - The figure shows schematic view of solar cell.    Substrate (500)    Intrinsic, undoped amorphous Si:H layer (505)    Layer of n-doped Si:H (510)    Anti-reflective coating (515)    Transparent conductive oxide layer (520)    Layer of aluminum (525)