Characterization of Real-world and Accelerated Exposed PV Module Backsheet Degradation
Laura S. Bruckman1, Yu Wang1, Andrew Fairbrother2, Sophia Napoli3, Scott Julien4, Adam W. Hauser3, Liang Ji5, Kai-tai Wan4, Gregory S. O'Brien3, Roger H. French1, Michael D. Kempe6, Xiaohong Gu2, Kenneth P. Boyce5
1Case Western Reserve University, Cleveland, OH, United States
/2National Institute of Standards & Technology, Gaithersburb, VA, United States
/3Arkema, King of Prussia, PA, United States
/4Northeastern University, Boston, MA, United States
/5Underwriter’s Laboratories Inc, Northbrook, IL, United States
/6National Renewable Energy Laboratory, Golden, CO, United States

Backsheet degradation is key to maintaining the lifetime of photovoltaic (PV) modules. Cracking, delamination, bubbling, and discoloration are main types of degradation. PV modules were collected from PV installations in multiple climatic zones. Multiple types of backsheets were obtained with poly(ethylene teraphlate) (PET) and polyamide air side layers being the largest number of backsheets retrieved. Multiple commercial PV backsheets were exposed to multiple accelerated exposures and key degradation mechanisms were identified. Polyamide backsheets showed cracking in retrieved modules and under accelerated exposures.  Poly(vinylidene fluoride) (PVDF) and poly(vinyl fluoride) (PVF) showed the highest stability in retrieved and accelerated exposures. While polyamide had the largest amount of large scale degradation.