NOVELTY - The solar cell (10) having an III-V material system useful in a satellite system, comprises an upper cell, a first upper metamorphic buffer layer below the upper cell, a middle cell below the upper buffer layer, a second upper metamorphic buffer layer below the middle cell, a lower cell below the second upper buffer layer, a lower metamorphic buffer layer, a substrate below the lower buffer layer, an iso-electronic surfactant buffer region (52) disposed on the substrate, a device layer, and a metamorphic sub-cell.    USE - The solar cell having an III-V material system is useful in a satellite system (claimed).    ADVANTAGE - The solar cell has improved efficiency and/or electrical power output, reduced threading dislocations and increased life time thus improving the performance and reducing the cost of the optoelectronic devices.    DETAILED DESCRIPTION - The solar cell (10) having an III-V material system useful in a satellite system, comprises an upper cell, a first upper metamorphic buffer layer below the upper cell, a middle cell below the upper buffer layer, a second upper metamorphic buffer layer below the middle cell, a lower cell below the second upper buffer layer, a lower metamorphic buffer layer, a substrate below the lower buffer layer, an iso-electronic surfactant buffer region (52) disposed on the substrate, a device layer, and a metamorphic sub-cell. The first, second and third upper metamorphic buffer layers are grown in the presence of a first, a second or a third iso-electronic surfactant. The buffer region is disposed between the substrate and the device layer and relaxed in the presence of the surfactant, and comprises a changing material composition between a lower-most portion and an upper-most portion of the buffer region. The changing material composition comprises an increasing or decreasing concentration of an element in the material composition. The device layer is lattice mismatched to the substrate. The first upper metamorphic buffer layer is graded in composition such that uppermost layers of the first upper metamorphic buffer layer are lattice matched to the upper cell. The second upper metamorphic buffer layer is graded in composition such that uppermost layers of the second upper metamorphic buffer layer are lattice matched to the middle cell. The lower metamorphic buffer layer is graded in composition and lattice matched to the substrate such that uppermost layers of the lower metamorphic buffer layer are lattice matched to the lower cell. The lower cell is lattice mismatched to the substrate, and a band gap of the lower cell is 0.6-1.3 eV. INDEPENDENT CLAIMS are included for:    (1) a satellite system; and    (2) a III-V device such as a light emitting diode, a laser diode, a solar cell, an avalanche photo-diode, a positive-intrinsic-negative diode, a hetero-junction bipolar transistor, a homo-junction bipolar transistor, a high-electron mobility transistor or a field effect transistor.    DESCRIPTION OF DRAWING(S) - The diagram shows a cross sectional view of solar cell.    Solar cell (10)    Sub cell (20, 40, 60)    Base layers (24, 44, 46)    Buffer region (52)    Nucleation layer. (58)