Busbar comprising: - a casing comprising a plurality of sidewalls (3,4,5,6) that delimit a cavity, - a tap-off opening formed in at least one of said sidewalls (3,4,5,6), - a plurality of busbar conductors (10, 11, 12, 13, 14) arranged parallel inside said cavity, wherein each busbar conductor extends along a longitudinal direction (X-X), is spaced from the adjacent busbar conductor along a first direction (Y-Y) perpendicular to the longitudinal direction (X-X) and has a central portion and two edge portions (10b, 10c) spaced from each other by the central portion, said edge portions (10b, 10c) of the busbar conductors extend longitudinally and are spaced from each other along a second direction (Z-Z) perpendicular to the longitudinal direction (X-X) and to the first direction (Y-Y), - clamping members externally coupled to said casing for holding said plurality of busbar conductors (10, 11, 12, 13, 14) inside said casing, - a plurality of tap-off elements (30, 31, 32, 33, 34), each tap-off element being stably fixed to a respective busbar conductor (10, 11, 12, 13, 14) and passing through said tap-off opening in order to bring electric current from said plurality of busbar conductors (10, 11, 12, 13, 14) to a power supply system, - said plurality of busbar conductors (10, 11, 12, 13, 14) extend along a straight direction inside said casing so that the distance between the busbar conductors (10, 11, 12, 13, 14) along the first direction (Y-Y) is constant inside said casing, characterized in that: - in each busbar conductor, the thickness of the central portion and of at least one of said two edge portions (10b, 10c), as measured in the first direction (Y-Y), have values s1 and s2 respectively, s2 being less than s1, - each tap-off element is stably fixed to a respective busbar conductor at a contact surface of said at least one edge portion (10b, 10c) having a thickness s2, the contact surface of the busbar conductor and the tap-off element being welded together. - a casing comprising a plurality of sidewalls (3,4,5,6) that delimit a cavity, - a tap-off opening formed in at least one of said sidewalls (3,4,5,6), - a plurality of busbar conductors (10, 11, 12, 13, 14) arranged parallel inside said cavity, wherein each busbar conductor extends along a longitudinal direction (X-X), is spaced from the adjacent busbar conductor along a first direction (Y-Y) perpendicular to the longitudinal direction (X-X) and has a central portion and two edge portions (10b, 10c) spaced from each other by the central portion, said edge portions (10b, 10c) of the busbar conductors extend longitudinally and are spaced from each other along a second direction (Z-Z) perpendicular to the longitudinal direction (X-X) and to the first direction (Y-Y), - clamping members externally coupled to said casing for holding said plurality of busbar conductors (10, 11, 12, 13, 14) inside said casing, - a plurality of tap-off elements (30, 31, 32, 33, 34), each tap-off element being stably fixed to a respective busbar conductor (10, 11, 12, 13, 14) and passing through said tap-off opening in order to bring electric current from said plurality of busbar conductors (10, 11, 12, 13, 14) to a power supply system, - said plurality of busbar conductors (10, 11, 12, 13, 14) extend along a straight direction inside said casing so that the distance between the busbar conductors (10, 11, 12, 13, 14) along the first direction (Y-Y) is constant inside said casing, - in each busbar conductor, the thickness of the central portion and of at least one of said two edge portions (10b, 10c), as measured in the first direction (Y-Y), have values s1 and s2 respectively, s2 being less than s1, - each tap-off element is stably fixed to a respective busbar conductor at a contact surface of said at least one edge portion (10b, 10c) having a thickness s2, the contact surface of the busbar conductor and the tap-off element being welded together.