Simulation and test of metastability of a-Si/µc-Si solar modules under outdoor conditions

This dissertation presents the work for analyzing outdoor-characterization of tandem solar modules of amorphous silicon (a-Si) and microcrystalline silicon (µc-Si) solar modules. Due to the Staebler Wronski effect (light-induced degradation and its temperature dependent annealing) the observation, monitoring and the simulation of the electrical performance pose challenges that have not been solved yet. And if long term data are available, the modules are not produced anymore. This work improves the possibilities for the simulation of long-term data with the diode model under different climatic regions. For simulation of the metastability effects of thin film solar cells it is necessary to determine every parameter of the diode model under several climate environmental conditions. By determination of the variation of every parameter, it is possible to transmit this for other climatic regions. The most important parameters are the serial resistance, the parallel resistance, the photo current, the diode (diode factor and saturation current) and the recombination current. The solar modules observed under outdoor conditions are a single-junction amorphous module, an amorphous/microcrystalline tandem module and a monocrystalline module for comparison reasons. The saturation current represents the behavior of the diode. This is why it can be applied to the dangling bonds caused by the Staebler-Wronksi effect. The dangling bonds behavior is analyzed and transposed to other climatic conditions, so that this simulation gives predictions about the performance and metastability of a-Si and µc-Si solar cells under different climatic conditions. For this simulation the photo current and the spectral response need to be determined under outdoor condition. In this work a method is presented, how it can be calculated without direct measurements by measured temperature and irradiation data and the parameters of the diode model.