High Temperature Solar Cell for Space/Terrestrial Applications 1999-01-2581
Most current TPV systems use either large radiators or enhanced cooling systems to keep the photovoltaic cell (PV) temperature close to room temperature. As a result, two problems are encountered: one is that the large radiator leads to significant integration problems with the spacecraft and limited sensor view angles. The other is that the enhanced cooling components not only reduce the system efficiency but also add moving parts in the system, which contradicts one of the TPV benefits of no moving parts. It is clear that the issue of cell temperature is crucial for space/terrestrial applications. Thus, in order to make the TPV system suitable for these applications, this temperature problem must be resolved. If the solar cells can be operated in the 150 to 225 °C range, the radiator will be significantly reduced. The strategy for this research is to select cells with a wider bandgap and then shrink the bandgap by raising cell temperature to ensure a match to selective emitters. This is because the cell bandgap is a function of temperature. In this paper, two types of InAsP cells were carefully designed to have bandgap of 1.22 and 0.96 eV, respectively. Both cells were operated at elevated temperatures and their response to selective light (e.g. 1.22 eV cell will be illuminated by 1.0 μm light and 0.96 eV cell will be illuminated by 1.5 μm light) was measured. The performance of these cells at elevated temperature is reported in this paper.