A solar concentrator comprising: at least one solar cell comprising a front surface, and an optical system concentrating solar radiation towards the solar cell, the system comprising an optical stepped lens (41; 20; 100; 110) having a front surface (21; 105) for receiving the solar radiation and an opposite rear surface (22; 106) facing the front surface of the solar cell, the rear surface having a stepped profile defining a plurality of stepped structures (46; 24; 102; 116,117), wherein: each stepped structure, in a cross-sectional plane of the lens, has a saw-tooth shape and is formed by a slope facet (29; 66; 93) and a draft facet (28; 67; 94), the slope and draft facets having different inclinations, each stepped structure being characterised by a pitch, wherein the slope facet extends for a first length in the cross-sectional plane and the draft facet extends for a second length in the cross-sectional plane; the front surface of the lens comprises a plurality of contiguous lenticular converging elements (47; 23; 101; 113,118), each lenticular element having a first and a second peripheral edge and a width (w L) extending between the first and the second peripheral edges; each lenticular element lies opposite to a corresponding stepped structure, the number of the plurality of lenticular elements corresponding to the number of the plurality of stepped structures, and each lenticular element has an outwardly convex surface in the cross-sectional plane and a width equal to the pitch of the corresponding stepped structure. at least one solar cell comprising a front surface, and an optical system concentrating solar radiation towards the solar cell, the system comprising an optical stepped lens (41; 20; 100; 110) having a front surface (21; 105) for receiving the solar radiation and an opposite rear surface (22; 106) facing the front surface of the solar cell, the rear surface having a stepped profile defining a plurality of stepped structures (46; 24; 102; 116,117), wherein: each stepped structure, in a cross-sectional plane of the lens, has a saw-tooth shape and is formed by a slope facet (29; 66; 93) and a draft facet (28; 67; 94), the slope and draft facets having different inclinations, each stepped structure being characterised by a pitch, wherein the slope facet extends for a first length in the cross-sectional plane and the draft facet extends for a second length in the cross-sectional plane; the front surface of the lens comprises a plurality of contiguous lenticular converging elements (47; 23; 101; 113,118), each lenticular element having a first and a second peripheral edge and a width (w L) extending between the first and the second peripheral edges; each lenticular element lies opposite to a corresponding stepped structure, the number of the plurality of lenticular elements corresponding to the number of the plurality of stepped structures, and each lenticular element has an outwardly convex surface in the cross-sectional plane and a width equal to the pitch of the corresponding stepped structure. each stepped structure, in a cross-sectional plane of the lens, has a saw-tooth shape and is formed by a slope facet (29; 66; 93) and a draft facet (28; 67; 94), the slope and draft facets having different inclinations, each stepped structure being characterised by a pitch, wherein the slope facet extends for a first length in the cross-sectional plane and the draft facet extends for a second length in the cross-sectional plane; the front surface of the lens comprises a plurality of contiguous lenticular converging elements (47; 23; 101; 113,118), each lenticular element having a first and a second peripheral edge and a width (w L) extending between the first and the second peripheral edges; each lenticular element lies opposite to a corresponding stepped structure, the number of the plurality of lenticular elements corresponding to the number of the plurality of stepped structures, and each lenticular element has an outwardly convex surface in the cross-sectional plane and a width equal to the pitch of the corresponding stepped structure.