PERSISTENT FEATURE DETECTION

Methods are presented for improved detection of persistent or systematic defects induced during the manufacture of a product. In particular, the methods are directed to the detection of defects induced systematically in the manufacture of photovoltaic cells and modules. Images acquired from a number of samples are combined, enhancing the systematic defects and suppressing random features such as variations in material quality. Once a systematic defect is identified, steps can be taken to locate and rectify its cause.