NOVELTY - The method involves removing a substrate (101). Metal grid lines placed on a top surface of a first solar subcell including a metal contact pad electrically connected to the metal grid lines and placed adjacent to a first peripheral edge of the first solar sub cell are deposited and lithographically patterned. An anti-reflection dielectric coating layer is deposited over the metal grid lines and an exposed top surface of a solar cell. A discrete inter-cell electrical interconnection unit is attached to the metal contact pad by using welding.    USE - Method for manufacturing a mounted III-V compound semiconductor inverted metamorphic multi-junction (IMM) photovoltaic solar cell on a semiconductor wafer in vertical, multi-junction structures for terrestrial solar power applications i.e. satellite and space related applications. Can also be used for manufacturing an optoelectronic device e.g. thermophotovoltaic (TPV) cell, photodetector and LED.    ADVANTAGE - The method enables permanently mounting the solar cell on a flexible support, and providing the electrical interconnection unit for connecting the solar cell to adjacent cells in a bifacial manner. The method enables depositing semiconductor layers in a metal organic chemical vapor deposition (MOCVD) reactor in a relatively simple and reproducible manner so as to minimize any physical damage to the deposited layers, thus ensuring relatively high yield of operable solar cells meeting specifications at conclusion of fabrication processes. The method enables providing reflectivity properties of metals from standard tables of reflectivity of metals that choice of silver can be a suitable choice for back contact in the solar cell so as to maximize reflectivity and efficiency of the solar cell. The method enables providing periodic reactor maintenance for removal of deposited materials so as to prevent adverse affects on reactor flow dynamics, so that repeatability and uniformity of epitaxial structures can be grown in a MOCVD reactor. The method enables using heterojunction subcells to improve short wavelength response for the subcells, effectively absorb and collect bulk of radiation in a narrower band gap base and increase short circuit current. The method enables using III-V arsenide compound, thus providing reduced cost, ease of growth, reactor maintenance, waste handling and personal safety to the solar cell.    DETAILED DESCRIPTION - METALLURGY - The method enables a metal electrode layer made of molybdenum. The method enables performing metal evaporation or soldering by using gold germanium, gold tin, lead tin and tin-silver-copper solders. The method enables a metal electrode layer including a sequence of layers with titanium/silver, silver/goldor, titanium/molybdenum/nickel/gold. The metal interconnection unit is made of material selected from a group consisting of molybdenum, nickel-cobalt ferrous alloy and nickel iron alloy material. The method enables lattice constant transition material to be made of material selected from a group consisting of indium-Gallium-aluminum-arsenic, arsenic, nitrogen and antimony based III-V compound semiconductors subject. The first subcell is made of material selected from a group consisting of a gallium-indium-phosporous, gallium arsenic, arsenic indium arsenic or gallium indium arsenic nitrogen. The method enables a metallic film to be a solid metallic foil or a metallic layer deposited on a surface of polyimide material. An INDEPENDENT CLAIM is also included for a multi-junction solar cell.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of a solar cell after deposition of semiconductor layers on a growth substrate.    Substrate (101)    Buffer layer (102)    Etch stop layer (103)    Window layers (105, 110, 118)    High band gap contact layer (122)