Optimization study of selective emitter thermophotovoltaic systems

At the NASA Lewis Research Center, the authors have developed a systems model for a general thermophotovoltaic (TPV) system. The components included in the model are a solar concentrator, receiver, emitter, window, filter and photovoltaic (PV) array. The system model requires the concentrator and receiver efficiencies, the wavelength dependence of the optical properties of the components, together with the emitter temperature, and the PV cell spectral response and current-voltage characteristic. With these inputs, the system efficiency and power output are calculated. For a selective emitter TPV system it is the emitter spectral emittance that is the major determinant of system performance. In this paper, the authors present results of an optimization study of a selective emitter TPV system. They vary the emitter temperature, the spectral emittances and emission bandwidth of the emitter, the PV cell bandgap energy, the cell back-surface reflectivity, and the long-wavelength emission band limit of the emitter, and discuss the effects that the variation of each of these parameters has on system performance.