Solar Thermophotovoltaic Converter with Fresnel Lens and GaSb Cells

Developing of a solar thermophotovoltaic system is being reported. Theoretical calculations for system parameters (emitter aperture absorptance, emitter efficiency, PV cell band gap etc.) optimization and overall efficiency estimation are presented. The calculations are mainly oriented to make all the parts of the system matched to each other: the choice of tungsten emitter dimensions, PV cell material etc. 20% STPV module efficiency is reachable for GaSb based receiver with a possible increase to 29% for a tandem PV cell and advanced technology of STPV module. A cost-effective two-stage concentrator module based on a primary Fresnel lens and secondary quartz concave-convex lens have been fabricated. Concentration ratio of ~4000x, necessary for obtaining high efficiency of the concentrator-emitter system, is ensured. Two types of TPV receivers are tested under outdoor conditions (850 W/m² average direct sun intensity) and with the solar simulator set up. Emitter temperatures in the range of 1400-2000K are registered and GaSb PV cell short circuit current density up to 5 A/cm² is observed. BeO ceramics is used for mounting the PV cells allowing high thermal conductivity and series connection of the cells. High PV efficiency (19% under tungsten emitter irradiation) is obtained in GaSb TPV cells