Quantitative description of dark current-voltage characteristics of multicrystalline silicon solar cells based on lock-in thermography measurements

摘要

A model is introduced which divides a solar cell locally into a 'baseline' region, showing a homogeneous exponential characteristic with a low ideality factor, and local 'shunt' regions which additionally show an inhomogeneous depletion region recombination current with a high, locally varying ideality factor. By measuring only three lock-in thermograms and the corresponding currents at one reverse and two different forward biases, the local ohmic contributions, the positions of the shunt regions, the diode parameters of the baseline region, and the local diode parameters of the shunt regions are obtained. Based on these data a good fit of dark current-voltage characteristics of real solar cells over the whole bias range is obtained. These data may be used in a local network model of the cell.