Photovoltaic cells for solar powered TPV systems

In present paper, different aspects of a solar powered TPV system are under theoretical and experimental study, such as heating the emitter of photons by focusing sunlight, returning the sub-bandgap photons by reflecting IR radiation from cell back surface, and estimating the cell conversion efficiency being guided by semiempirical approaches. Efficiency of 25% can be obtained in GaSb cells without photon recirculation illuminated by tungsten emitter heated up to 2200-2500 K. Efficiency exceeding 30% can be achieved in GaSb PV cells assuming 90% reflection of sub-bandgap photons back to the emitter. GaSb based TPV photoreceivers of cylindrical and flat geometry were developed and investigated outdoors. Photocurrent density as high as 4.5 A/cm/sup 2/ and PV cell efficiency of 14% have been obtained in the modules.