Solar Thermophotovoltaic Electric Generator for Remote Power

Essential Research, Inc. proposes to build a thermophotovoltaic (TPV) electric generator using a solar concentrator heat source with thermal storage capability, a selective emitter, and a photovoltaic cell. The operation point of the heat source and selective emitter will be approximately 1700K. The moderate operating temperature was chosen to provide a system energy conversion efficiency of greater than 20% and the high reliability required for military operations. The heat source is a solar concentrator dish developed by McDonnell Douglas Aerospace. The selective emitter will be a single or polycrystalline host material (such as garnet) doped with rare-earth oxides. A narrow band gap photovoltaic cell will be fabricated by the organo-metallic vapor phase epitaxy (OMVPE) deposition of InGaAs on InP substrates. The bandgap of the photovoltaic cell will be tailored to optimize the conversion of the selective emitter spectra, even though this will result in a lattice mismatch between the film and the substrate. The defects generated by the mismatch will be passivated with hydrogen to optimize the electrical properties of the photovoltaic cell. We believe that this technology will provide excellent conversion efficiencies in a commercially viable process. At the end of Phase I, we will demonstrate this technology by developing an emitter/cell combination (a converter) having a 15% conversion efficiency. In Phase II, a prototype TPV generator to deliver between 500-1000 W of electricity will be deployed. A final system efficiency of greater than 20% is anticipated. A solar TPV system can be a cost effective, compact, highly efficient, totally radiation hard replacement for any electric generator used in space or on earth where continuous or intermittent sunlight is available. Solar TPV will be a zero emission, high power system which uses a renewable energy source. It will be very reliable and quite, and it contains a battery-less maintenance free long life energy storage system. The system can be easily scaled to provide power levels suitable for many commercial or military uses.