Extreme weather conditions like severe hailstorms can lead to visible damage of the modules, as well as to micro-damage that is difficult to identify visually. For this reason, solar modules are compulsorily tested for hail resistance according to international standards (IEC 61215). The test is performed at a temperature of about 4 \( _{}^{o}\textrm{C} \), using special hail ball launchers with a diameter of 1 inch (25.4 mm) and a weight of about 7.53 g. The hail balls hit the panel in 11 cycles at a velocity of 23 \( \frac{m}{s} \). At the end of the test, there should be no visible damage such as cell and glass cracks, microcracks and structural deformations ( Fig. 1 ).