The utility model relates to a horizontal reversible busbar and photovoltaic junction box from north to south, the busbar divides X axle and Y axle two main part orientation, and the busbar body partly uses the centre to be the distribution of decreasing progressively step by step as maximum cross -section, the past left and right sides, this photovoltaic junction box provides lightning protection device, always converge electrical components, the electrical components of branch in the box of closed, the electrical components of branch divides two parts to arrange the electrical components both sides of converging always respectively, and other 2 components an electrical components arrange at the upside, and the lightning protection device is also arranged in the upside with its protection device. The utility model discloses a photovoltaic junction box has effectively utilized the box space, has reduced whole volume of junction box and installation space, simultaneously, this kind of mode of connection and busbar shape make convenient more, the easy protection of junction box back panel wiring, security and reliability higher. Shorten current path, reduced system's electrical loss, the different parts of vertical, horizontal reversible busbar adopt the sectional areas that vary, have reduced the metal material quantity, have effectively reduced manufacturing cost.