A recent report based on a survey by DuPont Photovoltaic Solutions has found that the overall rate of module defects globally has increased by 34% in 2018. The report points out the failures with various backsheets like PET, polyamide, and highlights issues with glass on glass modules.

The report also highlights the trends in module failures and defects, chronicles backsheet defects by panel age, and provides comprehensive data on backsheet defects by temperature and climate.

DuPont surveyed sites in North America, Europe, Asia, and the Middle East. The team compiled global data from 6.5 million modules, 355 installations, and 1.8 GW of installed solar photovoltaic capacity.

According to DuPont, while there were no defects in the majority of module materials, the following defects were observed:

• Cell/Interconnect – corrosion, hot spot, snail trails, broken interconnect, cracks, burn marks
• Backsheet – outer-layer (airside) and inner-layer (cell side) cracking, delamination, yellowing
• Encapsulant – discoloration, browning, delamination
• Other – glass defects, loss of AR coating, junction box

With 1.8 GW of projects inspected, here’s what they found: total module defects were 34%, total backsheet defects were 14%, backsheet defects increased 47% from 2018 and that cracking comprises 66% of all backsheet defects.

Higher temperatures cause backsheet defects to accelerate. These rates are 75% greater for rooftop installations than ground-mounted, as the roof-mounted systems typically run 15°C higher than ground-mounted. Cracking and delamination can compromise the electrical insulation of the module. Yellowing can lead to mechanical degradation and embrittlement of many backsheet polymers according to the report.

This 2019 report was assembled from inspection and analysis by DuPont teams using a variety of criteria including component, material, mounting, time in service, and climate.

This report could be a matter of concern for some solar developers in India who are already compromising on quality standards by procuring cheap products while the solar tariffs keep plummeting. In the past, Mercom has written about how the lack of regulations for product quality certification, intense competition, and absence of requisite awareness has only emboldened the quality problem in India’s rooftop solar sector.

Until recently, there were no policies or rules for maintaining the quality of projects in India. In March 2019, the Ministry of New and Renewable Energy (MNRE) issued a set of guidelines to be followed by solar manufacturers for models of modules that will be utilized in government-owned projects and those set up for the sale of electricity to the government.