The UV fluorescence test is based on the fact that no fluorescence is observed in the encapsulant at the time of microcrack formation.

But within the first months, in outdoor spaces, the polymer changes due to the influence of various climatic factors (in particular, radiation) and operating conditions in such a way that fluorescence is created in the entire upper layer of the PV module under ultraviolet radiation.

However, as moisture and oxygen can penetrate the cells through the polymer backsheet, fluorescence is reduced.

With longer exposure time, the area of oxygen confinement increases, resulting in ‘dark’ perimeters around the PV cells during exposure to ultraviolet radiation, because the induced fluorescence in the polymer is rapidly suppressed by the existing oxygen molecules.

Thus, the combined use of electroluminescence and ultraviolet fluorescence tests allows us to draw safe conclusions about the time of microcrack formation.

The ultraviolet fluorescence test is carried out using Smart UV Light.