Interview: Rajaram Pai

Rajaram Pai,
Business Leader - South Asia & ASEAN at DuPont Photovoltaic Solutions

“What kind of insights do we have from DuPont's annual Global Field Reliability Study from the Indian perspective?”

DuPont has been collecting data on material degradation for almost a decade through field inspections across the world to see how panels perform in various climates. As per 2019 DuPont global field studies, out of 0.7 GW panels inspected in India, approximately 11% of panels exhibited backsheet defects. The backsheet defect rate went up to ~35% in 4+-year-old installations. For backsheet materials, defect rate in polyethylene terephthalate (PET), polyamide (PA), polyvinylidene fluoride (PVDF) and coating based backsheets was found to be in the range of 14-70% in 4+ years old plants (most of these plants were less than 10 years).

The findings suggest the following conclusions which are relevant for Indian installations:

Backsheet failures are typically observed after 4-7 years of field exposure. Failure rate and defect severity increase as the modules age.

Quality of backsheets depends on their materials. While no backsheets failures were observed in Tedlar® polyvinyl fluoride (PVF) based backsheets, defect rates increased substantially (in the last 5 years) as manufacturers started using new, but unproven, materials (over last 10 years).

Many plants across the globe are still new (less than 4 years old) but they have PV modules with backsheet materials that have shown premature degradation between 5 – 8 years and are highly likely to show backsheet failures over the next few years.

“What kind of role does a backsheet play in maintaining the efficiency and long-lasting working of a module?”

Solar backsheets are a critical outer layer of solar panels. They provide the first line of defence for solar cells and encapsulating materials, protecting them from environmental stresses including moisture and UV while providing electrical insulation from high voltage. They are key to ensure optimal and sustained power output over the panel’s lifetime as well as the safe operation of PV systems. Long-term outdoor exposure is the ultimate test for all module components, material quality, and manufacturing quality.

“How suitable is Tedlar® for the varying Indian climatic conditions?”

DuPont™ Tedlar® PVF film-based backsheets have now been tested in the field for more than 30 years in all kinds of climates (desert, tropics, temperate, marine, mountain) and have a field-proven track record of protecting solar panels for 35+ years in the service environment with very low defect rates. Even in extreme outdoor conditions, the possibility of failure is very low and Tedlar® based backsheets can help reliable performance in the field.

Interview 08/04/2020 by News Bureau
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