High Throughput Detection of Cracks and other Faults in Solar PV Modules using a High-Power Ultraviolet Fluorescence Imaging System
Braden H. Gilleland1,2, William B. Hobbs1, Joseph B. Richardson1,3
1Southern Company, Birmingham, AL, United States
/2School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, United States
/3School of Engineering, University of Alabama at Birmingham, Birmingham, AL, United States

Ultraviolet Fluorescence (UVF) is an emerging PV module inspection technique capable of detecting cracks and other faults. To develop UVF as a practical inspection technique, a new UVF imaging system was developed for nighttime operation which utilizes a high-power UV source and a consumer camera to capture UVF images of multiple modules. The system achieves consistent throughputs above 1000 modules/hour, while costing less than $3500 and fitting inside a carry on. The system was demonstrated at 7 sites, consisting of 11 distinct module models (aged 1 to7 year(s) old) from 7 manufacturers. UVF was observed at all sites and cracks were detected at all but one. The broad sample has evidenced UVF's ability to detect cracks, hotspots, backsheet scratches (damage), backsheet cracks (degradation), and broken modules while also demonstrating the ubiquity and variability of UVF. An application of UVF and Electroluminescence at a recently storm-damaged site has demonstrated UVF’s application to insurance claims by further establishing its ability to discriminate between old and new cracks. As a complement to the high-throughput inspection, an automatic processing utility was developed for a single site which proved capable of detecting cracks with more than a 97.4 % accuracy. This utility is planned to be open-sourced and was developed to be immediately extensible to other sites. This work ultimately demonstrates the practicality of UVF by outlining a complete ground-based UVF workflow. 

Area: Sub-Area 8.6: Characterization Techniques for PV Modules and Systems (Joint between Topic Areas 5 and 8)