Monitoring and Diagnostics of Photovoltaic Cells by Electroluminescence

In the past decade, more than a dozen power plants with a peak capacity of more than 10 MW have been built in Hungary. Currently the largest solar power plant has a peak capacity of 100 MW. Observations of one of these power plants showed that peak performance was lower than expected. As a result, on-site inspection was needed. In addition to measured electrotechnical parameters, electroluminescence (EL) images were taken during the inspection. However, this paper primarily presents only the defect characterization of several PV cells using electroluminescence (EL). EL images can show the faults and give a comprehensive view of the real state of the solar cells. After a few years of operation many types of errors can be detected in the images of the cells. There are a wide variety of faults from microcracks to large cell breaks. In this study, we characterize the most common errors. This problem can be caused for several reasons. These reasons can also be manufacturing, installation, and operational errors. Depending on the quantity, damaged cells can lead to the failure of the entire module, which in the case of many faulty modules can already lead to control problems during the operation of the solar power plant.