NOVELTY - A chalcopyrite semiconductor based photovoltaic solar cell (10) comprises a metal substrate (12); a chalcopyrite semiconductor (18); and a conductive layer (16) between the metal substrate and the chalcopyrite semiconductor, where the conductive layer has a crystal structure that fits/matches to the crystal structure of the chalcopyrite semiconductor.    USE - As a chalcopyrite semiconductor based photovoltaic solar cell (claimed).    ADVANTAGE - The matching crystal structures of the chalcopyrite semiconductor and the adjoining conductive layer, provides a coherent interface between the conductive layer and the semiconductor, reducing the risk of detachment, and thus offering an increased stability to the solar cell, with an improved adhesion between the conductive layer and the chalcopyrite semiconductor. The greater the similarity between the crystal structures of the conductive layer and the chalcopyrite semiconductor, the greater the bonding between the conductive layer and the chalcopyrite semiconductor. The chalcopyrite semiconductor based photovoltaic solar cell, exhibits improved performance. The additional layers on top of the chalcopyrite semiconductor, provides protection against environment, reducing ageing and corrosion, and thus increasing the lifetime of the solar cell. The coated metal substrate used in production of photovoltaic solar cells, has a strip shape. The strip is easily manufactured in a roll to roll process to form individual coated metal substrate, thus offering cost advantage over piece by piece coating of the metal substrate as observed in prior art.    DETAILED DESCRIPTION - A chalcopyrite semiconductor based photovoltaic solar cell (10) comprises a metal substrate (12); a chalcopyrite semiconductor (18); and a conductive layer (16) between the metal substrate and the chalcopyrite semiconductor, where the conductive layer has a crystal structure that fits/matches to the crystal structure of the chalcopyrite semiconductor. The solar cell further comprises a diffusion barrier layer (14) between the metal substrate and the conductive layer; and additional semiconductor(s) (20, 22) selected from i-type and n-type semiconductors, which have crystal structure that fits to the crystal structure of the chalcopyrite semiconductor. INDEPENDENT CLAIMS are included for the following:    (1) a coated metal substrate for a photovoltaic solar cell, comprising a semiconductive coating layer having an octahedral or orthorhombic structure, preferably made of a vanadium oxide based compound; and a metal substrate; and    (2) a method for producing the coated metal substrate useful in production of photovoltaic solar cells, involves providing a metal substrate with a semiconductive layer having a octahedral or orthorhombic structure, preferably made of a vanadium oxide based compound.    DESCRIPTION OF DRAWING(S) - The figure shows a photovoltaic cell.    photovoltaic solar cell (10)    metal substrate (12)    diffusion barrier layer (14)    conductive layer (16)    chalcopyrite semiconductor (18)    additional semiconductors (20, 22)    electrode grid. (24)