NOVELTY - A multijunction solar cell comprises: an upper first solar subcell; a middle second solar subcell; a graded interlayer; a lower solar subcell; a metal contact layer; and a cut-out.    USE - The multijunction solar cell is useful for converting solar energy into electrical energy, and for industrial application.    ADVANTAGE - The multijunction solar cell is highly efficient, and reliable..    DETAILED DESCRIPTION - A multijunction solar cell comprises: an upper first solar subcell having a first band gap disposed adjacent the top surface of the multijunction solar cell; a middle second solar subcell adjacent to the first solar subcell and having a second band gap smaller than the first band gap; a graded interlayer adjacent to the second solar subcell; the graded interlayer having a third band gap greater than the second band gap; a lower solar subcell adjacent to the interlayer, the lower subcell having a fourth band gap smaller than the second band gap such that the third subcell is lattice mismatched with respect to the second subcell; a metal contact layer adjacent to the lower solar subcell for making an electrical contact to it; and a cut-out extending from a peripheral edge along the top surface of the solar cell to the metal contact layer to allow an electrical contact to be made to the lower subcell from the top surface of the solar cell. An INDEPENDENT CLAIM is a multijunction solar cell string comprising: a first multijunction solar cell including a contact pad disposed adjacent the top surface of the multijunction solar cell along a first peripheral edge; a second multijunction solar cell disposed adjacent the first multijunction solar cell, having a top surface and a bottom surface, and including a cut-out extending from a second peripheral edge along the top surface of the second solar cell located adjacent the first peripheral edge of the first multijunction solar cell, and extending to a metal contact layer adjacent the bottom surface of the second multijunction solar cell to allow an electrical contact to be made to the metal contact layer; and an electrical interconnect extending between the contact pad of the first multijunction solar cell and the metal contact layer of the second multijunction solar cell.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of the solar cell.    Contact layer (104)    Window layer (105)    Metal layer (123)    Antireflective dielectric coating layer (130)    Grid lines (501)    Bottom contact pad (520)    Top contacts (521)    Interconnection (524)    Vacuum block (600)