Characterizing Gridline Wear-Out in Silicon PV Modules
DuraMAT strives to characterize gridline surface wear-out in silicon photovoltaic (PV) modules via accelerated tests.
These tests are performed on lab-scale laminated modules that replicate the behavior of modules deployed in field. So far, the effects of loading rate and contact pressure at the cracked gridline interface on electrical degradation have been studied, with loading rate proving to be substantially more significant. This result will further help with developing a degradation model that predicts electrical degradation from gridline wear-out due to different variables.
To design 50-year lifetime PV modules, electrical degradation due to silicon cell cracking must be characterized. Electrical degradation occurs when current-carrying gridlines isolate due to gridline wear-out that occurs at the crack interface because of external loading (wind, mechanical). Loading rate influences gridline wear-out more than contact pressure at the cracked gridline interface.
To qualitatively assess electrical degradation in accelerated tests, scanning electron microscopy of gridlines will also be performed to show gridline wear-out.
Core Objective
Multi-Scale, Multi-Physics Model
Team Members
Salil Rabade and Nick Bosco at the National Renewable Energy Laboratory (NREL)
Impact
This project will enable the prediction of electrical degradation due to gridline wear-out. It will provide an experimentally validated model to support the modeling efforts of adjacent DuraMAT programs.
Learn More
Bosco, Nick, Martin Springer, and Xin He. 2020. “Viscoelastic Material Characterization and Modeling of Photovoltaic Module Packaging Materials for Direct Finite-Element Method Input.” IEEE Journal of Photovoltaics 10 (5): 1424–1440.
Silverman, Timothy, Martin Bliss, Ali Abbas, Tom Betts, Michael Walls, and Ingrid Repins. 2019. “Movement of Cracked Silicon Solar Cells During Module Temperature Changes.” Presented at the 2019 46th IEEE Photovoltaic Specialists Conference, Chicago, Illinois, June 16–21, 2019.
Bosco, Nick, Andre Chavez, Vijaykumar Upadhyaya, and Sang Han. 2020. “Fatigue-Like Behavior of Silver Metallization Gridlines and Proposed Damage Mechanics Model.” Presented at the 47th IEEE Photovoltaic Specialists Conference, Calgary, Canada, June 15–August 21, 2020.
Contact
To learn more about this project, contact Nick Bosco, NREL.
Minimum resistance, i.e., electrical degradation, is more prominent at slower loading rates (first column) than at faster loading rates (second column) in cyclic accelerated tests. Loading rate as a stand-alone variable is also more significant than the interaction between loading rate and contact pressure.
