Study of Shunt Distributions in Thin Film Multijunction Solar Cells

Abstract

The thin film technology of photovoltaic modules is perspective from the low cost point of view and with the respect of special, for example flexible modules. However, within a range of allowed temperature it is hard to prepare a high quality semiconductor material. On the other hand the technology can easily adopt a complex multi-layer structure, particularly a tandem structure, in which the cell with the narrower band gap is covered by the one with the wider band gap. For the characteristics and diagnostics of tandem cells it is necessary to distinguish the contributions of the component sub-cells to the total performance. One of the tasks is the determination of the component contributions to the total voltage, which is strongly influenced by the amount and spatial distribution of shunts in each sub-cell. We show that the total voltage is not a simple sum of component voltages. The experimental results are presented in this paper.