A box for connecting a solar panel to a cable has a generally planar flat base securable to a solar panel, forming a transversely open cavity for connection of elements of the solar panel with the cable, and formed with a laterally open aperture. A flat cover fittable transversely with the base to close the cavity is formed with an aperture forming with the aperture of the base when the cover is fitted to the base a hole that opens generally parallel to the base into the cavity and that is snugly fittable around the cable. A clip fixed on the base adjacent the aperture forms a mouth fittable around the cable extending through the hole and open generally parallel to the base.