Dr. Liang Ji Profile

Dr. Liang Ji

at Underwriters Labs Inc

SPIE Involvement:

Author

Publications (6)

Proceedings Article | 18 September 2018 Presentation

Degradation analysis of polyamide-based backsheets in field photovoltaic modules under different climatic conditions (Conference Presentation)

Yadong Lyu, Andrew Fairbrother, Jae Hyun Kim, Xiaohong Gu, Michael Kempe, Liang Ji, Kent Whitfield, Kenneth Boyce, Adam Hauser, Greg O’Brien, Scott Julien, Kai-Tak Wan, Yu Wang, Laura Bruckman, Roger French

Proceedings Volume 10759, 107590F (2018) https://doi.org/10.1117/12.2325843

KEYWORDS: Climatology, Climate change, Solar cells, Oceanography, Spectroscopy

Read Abstract +

Proceedings Article | 23 August 2017 Paper

Degradation analysis of field-exposed photovoltaic modules with non-fluoropolymer-based backsheets

Andrew Fairbrother, Scott Julien, Kai-Tak Wan, Liang Ji, Kenneth Boyce, Sebastien Merzlic, Amy Lefebvre, Greg O'Brien, Yu Wang, Laura Bruckman, Roger French, Michael Kempe, Xiaohong Gu

Proceedings Volume 10370, 1037003 (2017) https://doi.org/10.1117/12.2272488

KEYWORDS: Photovoltaics, Solar cells, Polymers, Reliability, Optical inspection, Colorimetry, Raman spectroscopy, Infrared spectroscopy

Read Abstract +

The selection of polymeric materials utilized in photovoltaic (PV) modules has changed relatively little since the inception of the PV industry, with ethylene-vinyl acetate (EVA), polyethylene terephthalate (PET), and fluoropolymer-based laminates being the most widely adopted primary components of the encapsulant and backsheet materials. The backsheet must serve to electrically insulate the solar cells and protect them from the effects of weathering. Due to continued downward pressure on cost, other polymeric materials are being formulated to withstand outdoor exposure for use in backsheets to replace either the PET film, the fluoropoymer film, or both. Because of their relatively recent deployment, less is known about their reliability and if they are durable enough to fulfill the ≥25 year warranties of current PV modules. This work presents a degradation analysis of field-exposed modules with polyamide- and polyester-based backsheets. Modules were exposed for up to five years in different geographic locations: USA (Maryland, Ohio), China, and Italy. Surface and cross-sectional analysis included visual inspection, colorimetry, glossimetry, and Fourier-transform infrared spectroscopy. Each module experienced different types of degradation depending on the exposure site, even for the same material and module brand. For instance, the polyamide-based backsheet experienced hairline cracking and greater yellowing and chemical changes in China (Changsu, humid subtropical climate), while in Italy (Rome, hot-summer Mediterranean climate) it underwent macroscopic cracking and greater losses in gloss. Spectroscopic studies have permitted identification of degradation products and changes in polymer structure over time. Comparisons are made to fielded modules with fluoropolymer-based backsheets, as well as backsheet materials in accelerated laboratory exposures. Implications for qualification testing and service life prediction of the non-fluoropolymer-based backsheets are discussed.

Proceedings Article | 23 August 2017 Paper

Model development of degradation of PV modules backsheet with locating place of module

Yu Wang, Andrew Fairbrother, Sebastien Merzlic, Scott Julien, Lucas Fridman, Camille Loyer, Amy Lefebvre, Gregory O'Brien, Xiaohong Gu, Liang Ji, Kenneth Boyce, Michael Kempe, Kai-tak Wan, Roger French, Laura Bruckman

Proceedings Volume 10370, 103700L (2017) https://doi.org/10.1117/12.2274209

KEYWORDS: Solar cells, Climatology, FT-IR spectroscopy, Photovoltaics, Humidity, Positron emission tomography, Spectroscopy

Read Abstract +

Proceedings Article | 2 November 2016 Presentation

Cross-correlation of backsheet degradation between real-world exposed modules and accelerated exposures of backsheet materials (Conference Presentation)

Laura Bruckman, Roger French, Yu Wang, Michael Kempe, Amy Lefebvre, Xiaohong Gu, Liang Ji, Kai-Tak Wan, Christopher Flueckiger

Proceedings Volume 9938, 993805 (2016) https://doi.org/10.1117/12.2238162

KEYWORDS: Data modeling, Solar cells, Atmospheric modeling, Climatology, Performance modeling, Polymers, Meteorology, Data acquisition, Feature selection, Nondestructive evaluation

Read Abstract +

Proceedings Article | 8 October 2014 Paper

Thermal performance of microinverters on dual-axis trackers

Mohammad Hossain, Timothy Peshek, Yifan Xu, Liang Ji, Jiayang Sun, Alexis Abramson, Roger French

Proceedings Volume 9179, 91790J (2014) https://doi.org/10.1117/12.2061235

KEYWORDS: Solar cells, Photovoltaics, Temperature metrology, Capacitors, Data analysis, Reliability, Statistical analysis, Data modeling, Field effect transistors, Thermal modeling

Read Abstract +

Proceedings Article | 16 October 2012 Paper

Examination of a size-change test for photovoltaic encapsulation materials

David Miller, Xiaohong Gu, Liang Ji, George Kelly, Nichole Nickel, Paul Norum, Tsuyoshi Shioda, Govindasamy Tamizhmani, John Wohlgemuth

Proceedings Volume 8472, 84720T (2012) https://doi.org/10.1117/12.929796

KEYWORDS: Aluminum, Glasses, Manufacturing, Standards development, Temperature metrology, Solar cells, Photography, Thermography, Photovoltaics, Solids

Read Abstract +

Showing 5 of 6 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years