Spread Spectrum Time Domain Reflectometry for Detecting Accelerated Degradation in Photovoltaic Cells    
Mashad Uddin Saleh1, Chris Deline2, Kent Terwilliger2, Byron McDanold2, Evan Benoit1, Samuel Kingston1, Naveen Kumar Tumkur Jayakumar1, Joel Harley3, Cynthia Furse1, 4, Michael Scarpulla1
1Department of Electrical Engineering, University of Utah, Salt Lake CIty, UT, United States
/2National Renewable Energy Laboratory, Golden, CO, United States
/3Department of Electrical Engineering, University of Florida, Gainesville, FL, United States
/4LiveWire Innovation, Camarillo, CA, United States

Abstract—Spread spectrum time domain reflectometry (SSTDR) is a broadband electrical reflectometry technique that has been used to detect and localize faults on live electrical systems. In this paper, we use SSTDR to electrically interrogate the responses of PV cells and mini modules to three accelerated degradation tests: damp heat, potential induced degradation, and humidity freeze. The SSTDR responses change in distinct ways for each test demonstrating that SSTDR can be used to identify the type of accelerated degradation in cells.