Electroluminescence tests are used to identify micro-damage that is not visible to the naked eye. This type of damage can occur e.g. during heavy hailstorms, when weather conditions are much more unfavorable than those during hail tests and as a consequence the strength limit of the panels may be exceeded. Micro-damage may also occur during transport or installation. Electroluminescence tests can also be used to detect micro-damage from induced PID voltage. They are performed when current flows through the module. At this time, two independent electroluminescent cameras take images of the photovoltaic cells so that the modules are overexposed. A detailed description of how the electroluminescence tests are performed is given in [1].