Failure analysis of field-failed bypass diodes

Xiao, Chuanxiao; Hacke, Peter; Johnston, Steven; Kern, Dana; Jiang, Chun Sheng; Al-Jassim, Mowafak

doi:10.1002/pip.3297

Title: Failure analysis of field-failed bypass diodes

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Abstract

Defective bypass diodes are often found as the largest factor leading to power loss in solar modules. Here, we report on failure mechanisms by investigating shunted bypass diodes from a rooftop installation, using a combination of multiple characterizations including current–voltage analysis, thermal-runaway testing, X-ray computed tomography, lock-in thermography, focused ion-beam cross-section imaging, chemical decapsulation, optical microscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy. Differing from static discharge typically associated with lightning strikes on modules, we found diode failure by the mechanism of thermal damage under continuous, long-term overstress in forward bias. Our conclusion is based on evidence of energy dissipated—the small to medium extent of melt-through on the Schottky diode face. The diode failure shows distortions or roughening of the Schottky diode metal-semiconductor interface with the die attach, and some failures are accompanied by die-attach solder melting. We propose that nonuniform irradiance on the modules caused diode shunting due to extended periods of heat dissipation in the modules, because modules in this string were placed in two different orientations. In contrast, a second parallel module string of the same module type on the same rooftop with a unique plane of array did not show any diode failures. The thermalmore »« less

Authors:

^[1]; Hacke, Peter ^[1]; Johnston, Steven ^[1];

^[1];

^[1]; Al-Jassim, Mowafak ^[1]

National Renewable Energy Lab. (NREL), Golden, CO (United States)

Publication Date:: Mon Jun 08 00:00:00 EDT 2020

Research Org.:: National Renewable Energy Laboratory (NREL), Golden, CO (United States)

Sponsoring Org.:: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office

OSTI Identifier:: 1660048

Alternate Identifier(s):: OSTI ID: 1632360

Report Number(s):: NREL/JA-5K00-73209
Journal ID: ISSN 1062-7995; MainId:6224;UUID:4df3a236-2f23-e911-9c1c-ac162d87dfe5;MainAdminID:13823

Grant/Contract Number:: AC36-08GO28308; AC36‐08GO28308

Resource Type:: Accepted Manuscript

Journal Name:: Progress in Photovoltaics

Additional Journal Information:: Journal Volume: 28; Journal Issue: 9; Journal ID: ISSN 1062-7995

Publisher:: Wiley

Country of Publication:: United States

Language:: English

Subject:: 14 SOLAR ENERGY; bypass diode; characterization; diode; failure analysis; heat dissipation; long-term overstress; rooftop nonuniform irradiance; Schottky diode interface; X-ray computed tomography

Citation Formats


                    Xiao, Chuanxiao, Hacke, Peter, Johnston, Steven, Kern, Dana, Jiang, Chun Sheng, and Al-Jassim, Mowafak. Failure analysis of field-failed bypass diodes.  United States: N. p., 2020. 
Web.  doi:10.1002/pip.3297.

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                    Xiao, Chuanxiao, Hacke, Peter, Johnston, Steven, Kern, Dana, Jiang, Chun Sheng, & Al-Jassim, Mowafak. Failure analysis of field-failed bypass diodes.  United States.  https://doi.org/10.1002/pip.3297

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                    Xiao, Chuanxiao, Hacke, Peter, Johnston, Steven, Kern, Dana, Jiang, Chun Sheng, and Al-Jassim, Mowafak. Mon .  
"Failure analysis of field-failed bypass diodes".  United States.  https://doi.org/10.1002/pip.3297.  https://www.osti.gov/servlets/purl/1660048.

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@article{osti_1660048,

  title        = {Failure analysis of field-failed bypass diodes},

  author       = {Xiao, Chuanxiao and Hacke, Peter and Johnston, Steven and Kern, Dana and Jiang, Chun Sheng and Al-Jassim, Mowafak},

  abstractNote = {Defective bypass diodes are often found as the largest factor leading to power loss in solar modules. Here, we report on failure mechanisms by investigating shunted bypass diodes from a rooftop installation, using a combination of multiple characterizations including current–voltage analysis, thermal-runaway testing, X-ray computed tomography, lock-in thermography, focused ion-beam cross-section imaging, chemical decapsulation, optical microscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy. Differing from static discharge typically associated with lightning strikes on modules, we found diode failure by the mechanism of thermal damage under continuous, long-term overstress in forward bias. Our conclusion is based on evidence of energy dissipated—the small to medium extent of melt-through on the Schottky diode face. The diode failure shows distortions or roughening of the Schottky diode metal-semiconductor interface with the die attach, and some failures are accompanied by die-attach solder melting. We propose that nonuniform irradiance on the modules caused diode shunting due to extended periods of heat dissipation in the modules, because modules in this string were placed in two different orientations. In contrast, a second parallel module string of the same module type on the same rooftop with a unique plane of array did not show any diode failures. The thermal damage failure of melt-through was caused by the long-term current generated by overstressing of diodes that may have had crystalline and impurity defects.},

  doi          = {10.1002/pip.3297},

  journal      = {Progress in Photovoltaics},

  number       = 9,

  volume       = 28,

  place        = {United States},

  year         = {Mon Jun 08 00:00:00 EDT 2020},

  month        = {Mon Jun 08 00:00:00 EDT 2020}

}

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