Thermal and Electroluminescence Imaging and Application to the Location and Classification of Defects in Crystalline and Multi-Crystalline Solar Cells
When a solar cell is illuminated by light from the sun, a current is generated that can be used to provide electrical power. Conversely, if we apply a current to a solar cell, light is generated and this process is called electroluminescence (EL). In Silicon solar cells the EL is very weak and in a perfect cell is extremely uniform. Defects inherent in the material, such as dislocations which degrade its performance or those created during the cell fabrication process, such as microcracks which affect its long term reliability can be clearly observed in EL imaging. We will investigate EL imaging in detail, by experiment and simulations, for the purposes of developing a production level tool to image defects in silicon solar cells and classify them using machine vision techniques to provide feedback to the manufacturing process and predictive information to module manufacturers.