Luminescence techniques are very powerful techniques for the detection and classification of defects in solar cells and panels.
Daylight EL technique is quite useful for offering safe inspection of solar plants on-site, with clear advantages respect to night EL (providing the same information, although with lower resolution).
Daylight PL does not need for a power source, although it still needs for electrical contacts.
The information provided is mainly related to C cracks or B/C cracks.
PL with an external source gives also useful information of the defects present in a solar cell, also cracks can be visualized. However, it is complicated to be performed on-site.
