Quantitative Analysis of the Influence of Shunts in Solar Cells by Means of Lock-in Thermography

Infrared lock-in thermography not only allows to image local heat sources like shunts in electronic devices like solar cells, but it also can measure currents flowing in certain regions of the device quantitatively in a non-destructive way. After dealing with the physical basics of quantitative lock-in thermography, two types of measurements are described: 1. The quantitative measurement of the I-V characteristic of a point shunt in a solar cell, and 2. the evaluation of the influence of shunts on the efficiency of the cell as a function of the illumination intensity. The investigation of a typical multicrystalline solar cell shows that the shunts deteriore predominantly the low light level performance of the cell.