NOVELTY - Operation of solar cell comprises: receiving incident radiation having an intensity of greater than 100 suns concentration, absorbing photons from incident radiation both within and outside the quantum well stack to generate electron hole pairs, and recombining electrons and holes with radiative recombination to form re-radiated photons that are re-absorbable within the solar cell to generate electrical energy.    USE - For operating a solar cell used for generating electrical energy.    ADVANTAGE - The method recognizes that using strain balanced multiple well quantum stack with greater than 30 quantum wells, which may be achieved without dislocations using strain balancing techniques, coupled with an appropriately matched bulk semi-conductor region bounding the quantum well stack enables high efficiency to be achieved and radiative recombination to dominate in a manner that the photons generated by such radiative recombination can be re-used.    DETAILED DESCRIPTION - Operation of solar cell having strain balanced multiple quantum well stack containing greater than 30 quantum wells and disposed between bulk semiconductor regions, a band-gap difference between a bandgap of a deepest well within the strain balanced multiple quantum well stack and a band-gap of the bulk semiconductor regions of the cell outside the multiple quantum well region being greater than 60 meV, comprises: receiving incident radiation having an intensity of greater than 100 suns concentration; absorbing photons from the incident radiation both within and outside the quantum well stack to generate electron hole pairs; and recombining electrons and holes with a radiative recombination to form re-radiated photons that are re-absorbable within the solar cell to generate electrical energy. Electrons and holes within the quantum well stack only recombine via the radiative recombination.    DESCRIPTION OF DRAWING(S) - The figure is a schematic illustration of a tandem solar cell arrangement including double strain balanced quantum well active regions.