NOVELTY - A monolithic photovoltaic junction comprises first and second oppositely doped semiconductor regions (32, 34); and intrinsic region disposed between doped regions, where intrinsic region having actual lattice size, and comprises quantum wells of first (36) and second type (37) and barrier (35) separating each of quantum wells, quantum wells of first type is formed of material having lattice constant, less than actual lattice size of intrinsic region, and quantum wells of second type is formed of material having lattice constant, greater than actual lattice size of intrinsic region.    USE - As monolithic photovoltaic junction for solar cell useful in photovoltaic system for generating electrical power from solar illumination (claimed).    ADVANTAGE - The junction utilizes two types of wells with opposite stress types that reduces the maximum stress differential between wells and barriers; reduce any such effects; and reduces local breakdown of the lattice coherence can be amplified by the strain differential at the interface between a quantum well and a barrier and trigger a local transition from 2D growth to 3D growth which rapidly propagates both laterally and along the growth direction with the formation of extended regions of highly damaged material by reducing the strain differentials between layers.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a solar cell comprising first photovoltaic junction, where the first photovoltaic junction is the photovoltaic junction;    (2) a photovoltaic system for generating electrical power from solar illumination comprising the solar cell; and a concentrator arranged to deliver concentrated sunlight to the surface of the solar cell; and    (3) forming the solar cell involving epitaxial growth of the first photovoltaic junction, where the first photovoltaic junction is the photovoltaic junction.    DESCRIPTION OF DRAWING(S) - The figure shows view of intrinsic region of solar cell.    First and second oppositely doped semiconductor regions (32, 34)    First type quantum well (36)    Second type quantum well (37)    Barrier (38)