Analysis Method for the Uniformity of a-Si-Based Multijunction Thin-Film Solar Module Using Ideality Factors

A methodology was developed to analyze the uniformity properties of amorphous silicon (a-Si) based triple-junction thin-film solar module for power stations or for building-integrated photovoltaic using circuit model parameters. First, a-Si-based triple-junction thin-film solar module with a size of 5G was fabricated via the mass production method. The module was divided into small modules with ten solar cells. A total of nine samples were selected and the dark I-V characteristics for each sample were measured. A circuit model for a triple-junction solar module was proposed. One sample that could represent the triple-junction properties was selected and the circuit parameters were extracted. The circuit model with the extracted parameters was simulated using H-spice and showed good agreement between experimental and simulation results. Ideality factors and reverse saturation currents from the selected samples were extracted from the dark IV curve and resistance parameters by using the numerical method with the circuit model. The distribution of each parameter for the samples and the uniformity of the large-size module were analyzed.