Visual and IR Inspection Analysis of PV Modules Installed at the Desert Climate of Qatar

Abstract

This study presents the results of visual and infrared (IR) inspection of photovoltaics (PV) technologies installed at the Qatar environment and energy research institute (QEERI) outdoor test facility (OTF) at Qatar Foundation (Doha, Qatar). Silicon based PV technologies which have been operational in the field since 2014, have been investigated for various failure modes. The visual inspections were carried out for all the PV modules from the backside however, the inspection from the front side was not possible for some modules due to heavy soiling. The visual defects which were identified during this study include, cracking of the back glass, yellowing of the encapsulant material, cracks formation in the back sheet, and pits formation in the back sheet. The visual inspection revealed that around 19 % of the total modules have back sheet cracking and discoloration, 8 % have yellowing of the encapsulant, and around 4 % were having pits in the back sheet. Moreover, one module was detected with back glass cracking. The IR inspection was also done both from front and backside for all the silicon PV modules to detect hot spots. The IR inspection has revealed that hot spots were generated at different locations of the PV modules. 39 % of the modules have hot spots at the location of junction boxes, around 6 % of the modules have hot spots in junction boxes and around 1 % have hot spots at the locations away from junction boxes. The visual and IR inspection has revealed that the dominant failure modes which have been observed for silicon-based technologies at OTF are the hot spots generation at junction boxes and the back sheet cracking, and its yellowing.