Within the framework of the electroluminescence process (EL), special cameras are used to visualize defects in photovoltaic systems that are not visible to the naked eye.

By using near-infrared sensors and a high-performance power supply in darkness (night), faulty spots are detected in the module. The faulty areas can be identified by the fact that they are not illuminated (electrically inactive areas).

With the electroluminescence method, damage caused by excessive mechanical stress during manufacture, assembly or operation or damage caused by hail or overvoltage can be very well detected. So-called PID or delamination damage to PV modules can also be clearly detected with the EL method.

Figure: Faulty spots in the module detected using the EL method	Figure: Start of a PID determined by EL procedure