Development of GaSb Photoreceiver Arrays for Solar Thermophotovoltaic Systems

Abstract

In comparison to conventional solar photovoltaics, where sun radiation is converted into electricity directly by solar cells, solar thermophotovoltaic (STPV) conversion has some specific advantages. These advantages come from the fact that in thermophotovoltaics the photon radiator is always inside the conversion system and near the photovoltaic cells. For these reasons we are developing small prototypes with sun heated emitters and photoreceiver arrays to be installed inside complete STPV systems. In order to achieve these complete STPV systems, the first step is to determine the optimum way of packaging the TPV cells into STPV arrays, choosing the best series/parallel configurations depending on the TPV cell band gap, the size of arrays, and the materials. This is the goal of this paper. To carry out the calculations, 18 and 24 cell arrays have been connected following different series and parallel configurations, using the PSPICE commercial circuit-simulation software. Each TPV cell is simulated as a block consisting of the well-known photogenerated current source, two dark diodes of ideality factors equal to one and two, and two resistances, one in parallel and the other in series. As a result, recommendations about the size and front grid design of the GaSb cells are obtained. When the optimally designed cells are connected to be included in two specific systems, recommendations about the best parallel/series connection are achieved. Evaluation on the performance of the arrays at nonuniform illumination is also carried out. The first photoreceiver arrays are being constructed and implemented in real STPV systems following these recommendations.