Optimization of Germanium Cell Arrays in Tungsten Emitter-based Solar TPV Systems.

This work presents a simulation study to find the best cell array configuration which leads to the maximum thermophotovoltaic (TPV) conversion efficiency in a specific solar thermophotovoltaic (STPV) system. First, the optical and electrical device parameters have been extracted from germanium TPV cells working at 25°C. Then, a cell model consisting of two parallel diodes and two resistances (series and shunt) has been developed for its use in SPICE® software. The parameters of this model have been obtained from the fitting of dark the I-V curve from germanium cells. In addition, the cell photocurrent density has been calculated by integrating the measured spectral response (SR) of the cells under a typical tungsten emission spectrum at different system view factors (VF), i.e. ratios of power density on the emitter surface to the power density on the receptor surface. Changing the VF leads to different light power densities reaching the receptor area for a fixed emitter temperature. Different emitter temperatures have also been taken into account in this study. They are directly related to the different re-emitting efficiencies expected for the concentrator-emitter system in a real STPV system. Finally, the overall array efficiency has been estimated for different array configurations working from 0.01 to the maximum view factor for each array configuration, which depends on the geometry and the number of cells in the array. The cell temperature effect on the efficiency has been also considered from the measured cells in flash equipment. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]