A device having a multi-junction solar cell and a protection diode structure, whereby the multi-junction solar cell and the protection diode structure have a common rear surface and front sides separated by a mesa trench. The common rear surface comprises an electrically conductive layer, and the light enters through the front side into the multi-junction solar cell. The cell includes a stack of a plurality of solar cells, and has a top cell, placed closest to the front side, and a bottom solar cell, placed closest to the rear side, and a tunnel diode is placed between adjacent solar cells. The number of semiconductor layers in the protection diode structure is smaller than the number of semiconductor layers in the multi-junction solar cell. The sequence of the semiconductor layers in the protection diode structure corresponds to the sequence of semiconductor layers of the multi-junction solar cell.