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DuPont recently released its latest Global Photovoltaic Reliability Report, with results from its highly developed field inspection and analysis program that monitors material degradation and its impact on module performance.
This unique and innovative program features a multi-step inspection protocol conducted by DuPont scientists and engineers in North America, Europe, Asia and the Middle East. A number of variables were analyzed in the course of the inspections including component, material, mounting, time in service and climate.
The 2020 field report was compiled from inspection and analysis of nearly 3 gigawatts (GW) of photovoltaic (PV) installations around the globe, spanning 9 million panels.
Key findings (compared to 2019):
- Total module defects: 30%
- Total backsheet defects: 16%
- The overall outer layer cracking rate of polyvinylidene fluoride (PVDF) backsheets increased by more than three times
Emerging trends in backsheet failures include:
- Rapid increase in cracking in PVDF backsheets
- Cracking of inner layers
- Delamination in double glass modules.
“As we begin a new decade, DuPont continues to work on assessing how panels and materials are aging in the field, often with sobering results,” said Dr. Kaushik Roy Choudhury, senior scientist and global technology leader, DuPont Photovoltaic Solutions. “As materials scientists we apply our skills on diagnosing and analyzing degradation in actual outdoor conditions, of both traditional glass/backsheet panels, as well as newer dual glass bifacial modules. The learnings and insights we collect from the field continue to point to the vital importance of selecting the appropriate Bill of Materials for solar panels, to help protect investments for the long-term.”
The DuPont team has observed nearly a four-fold cumulative increase in PVDF outer-layer cracking defect rates, from 5% to 23% between year four and year nine after installation in China, Europe, India and North America. Deeper backsheet cracks have led to backsheet delamination, exposing the core layer to elements and leading in some instances to inverter tripping and ground faults.
Inner layer cracking has been frequently encountered in fluoroethylene vinyl ether (FEVE) and polyethylene terephthalate (PET) backsheets. This can directly impact power through delayed inverter starts, ground faults and fires.
“Delamination and cracking were observed in multiple double glass module installations,” Choudhury said. “Delamination appears to originate near edges of a module or at individual cells, while cracks likely originate at scratches or chips on glass surfaces and edges or at stress risers introduced by the racking system”.
The comprehensive report is intended to help buyers and investors understand the breadth of component degradation issues and module failures that can occur in the field. The report can be downloaded free of charge at photovoltaics.dupont.com.