A multi-junction solar cell having a Ge or GaAs substrate, as well as a solar cell structure having several subcells deposited on the substrate, the substrate having peripheral side faces, and the solar cell structure having a peripheral circumferential surface, which runs spaced apart from the side faces. To prevent oxidation and penetration of moisture, the circumferential surface of the solar cell structure is coated with a protective, electrically insulating first coating under essential exclusion of the upper surface facing the rays, or that without encroaching on the solar cell structure, the side faces of the substrate are coated with a protective, electrically insulating second coating or that both the side faces of the substrate as well as the circumferential surface of the solar cell structure are coated with a third coating by essential exclusion of the upper surface facing the rays.