Detection of hot spot defects for crystalline solar cell

Detection of hot spot defects for c-Si solar cell module is studied by a high-resolution infra-red (IR) system with a resolution of 200 m in minimum. To compare the temperature effect generated by the hot spot defects, different types of damages were imposed in the solar cells while a non-damaged counterpart was studied as a control sample. The solar cell module was applied with forward and reverse current with a bias of 10xVoc. According to the test results, the forward current of 6 A generally heat up the solar cells for both damaged and non-damaged samples. For the reverse current test, the defected locations were heated up significantly with the testing time. To record the heating condition of different location, it is shown that the damaged location heated in various thermodynamic law, while the others stayed in a condition at room temperature. The temperature of local defects increased with the testing time, and heating profile follows a linear equation with a constant heating rate. To study the thermal behavior of the heating spot, a long tern monitoring was operated to detect the temperature kept around 125 °C since 90 s. The reverse-biased testing method is approved to distinguish the solar of hot spot risks and further to classify the solar cells.