Nondestructive estimation of strength deterioration in photovoltaic backsheets using a portable near infrared spectrometer

Li, Hua; Kikuchi, Ryoei; Kumagai, Masanori; Amano, Toshio; Tang, Haoning; Lin, Jin‐Ming; Fujiwara, K.; Ogawa, Norio

doi:10.1016/j.solmat.2012.01.017

Cited by 22 publications

(11 citation statements)

References 11 publications

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“…Practical in-field testing results showed that significant backsheet failures such as cracking, yellowing and delamination occurred withina 5-year service [2].Previous research efforts have investigated backsheet degradation and failure by studying either individual material components or mini-modules [2,3,[12][13][14][15][16][17][18]. Some studies focused on characterization of backsheet film as a whole as well asits top/bottom surfaces [2,[14][15][16], while others addressed the adhesion behaviorsbetween layers by peeling tests [3,12,13]. However, there arelimited data showing a degradation profile acrossbacksheetlayers and how different aging stresses impact individual layers [17,18].For this reason, an in-depth investigation on the degradation profileof polymeric multilayer backsheetisneeded for a betterunderstanding of backsheet failure mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Depth profiling of degradation of multilayer photovoltaic backsheets after accelerated laboratory weathering: Cross-sectional Raman imaging

Lin

Krommenhoek

Watson

et al. 2016

Solar Energy Materials and Solar Cells

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Understanding of thedurability of each individual layer and their interfaces in a multilayered photovoltaic (PV)backsheetis critical to the design and selection of materials for making reliable andhigh performance PV modules. In this study, Raman imaging was used to depth profile the chemical degradation of a multilayer commercial backsheetfilm exposed to ultraviolet (UV) radiationat 85°C, 5% relative humidity (RH, dry) and 85°C,60% RH (humid)on the NIST (National Institute of Standards and Technology) SPHERE(Simulated Photodegradation via High Energy Radiant Exposure).The backsheetfilm wasa multipartlaminate comprising of a pigmented polyethylene terephthalate (PET)-based outer layer, PET core layer and three ethylene vinyl acetate (EVA) layers having different vinyl acetate(VA) contents, along with two inner adhesive layers between PET outer and PET core layers, and PET core and EVA layers. Cross-sectional samples were prepared by cryo-microtomyfor various characterizations.The multilayer structureswere examined by laser scanning confocal andatomic force microscopies, while their chemical degradation profiles were obtained by Raman spectroscopic imaging. Non-uniform degradation was observed in the agedbacksheet film, and both UV and moisture appeared tosignificantly affect the degradation profiles of the multilayers.Severe degradation, indicated by high fluorescence,occurredin the outermost region of the pigmented PET outer layer, and the degradation gradient extended to approximately 20 µm to the bulk. It was also found thattheinner adhesive layerswere severelydeterioratedunder moist condition, indicating thatthe long-termadhesion between the layers could be a major area of concern for multilayer backsheets used in a humid environment. The relationship between the sharp 3 (non-uniform) degradation profile, resultant internal stress, and ultimate failures (cracking and delamination)was discussed as well.

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Section: Introductionmentioning

confidence: 99%

Depth profiling of degradation of multilayer photovoltaic backsheets after accelerated laboratory weathering: Cross-sectional Raman imaging

Lin

Krommenhoek

Watson

et al. 2016

Solar Energy Materials and Solar Cells

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“…Failure of PET after several thousand hours in damp heat (85ᵒ C -85% relative humidity) through a breakdown of the mechanical properties (e.g. cracking or reduction in tensile strength) has been observed by several groups [111][112][113]. Other work has suggested that PA and PO core layers exhibit less hydrolytic and thermal degradation than PET, and as expected most flouropolymers show very little loss in mechanical properties after damp-heat [114].…”

Section: Backsheet Degradationmentioning

confidence: 91%

Manufacturing metrology for c-Si module reliability and durability Part III: Module manufacturing

Davis

Rodgers

Scardera

et al. 2016

Renewable and Sustainable Energy Reviews

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This article is the third and final article in a series dedicated to reviewing each process step in crystalline silicon (c-Si) photovoltaic (PV) module manufacturing process: feedstock, crystallization and wafering, cell fabrication, and module manufacturing. The goal of these papers is to identify relevant metrology techniques that can be utilized to improve the quality and durability of the final product. The focus of this article is on the module manufacturing process. The c-Si PV module fabrication process can be divided into three primary areas; (1) stringing and tabbing, (2) lamination, and (3) integration of junction box and bypass diode(s). Each of these processing steps can impact the reliability and durability of PV modules in the field. The ultimate goal of this article is to identify appropriate metrology techniques and characterization methods that can be utilized within a module manufacturing facility to improve the reliability and durability of the final product. Additionally, a gap analysis is carried out to identify areas in need of further research and a discussion is provided that addresses new challenges for advanced materials and emerging technologies.

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“…However, as described in detail in the IEA PVPS Task 13 report on "Assessment of Photovoltaic Module Failures in the Field" [21], many PV module failure modes are related to unfavorable material interactions or material degradations. Thus, recently, several researches active in failure analysis of PV modules, e.g., [7,[22][23][24][25][26][27], started transferring the technically mature portable spectrometers (IR, Raman, NIR) to this different field of application and applied them for nondestructively • validating the bill of materials (BOM) of PV devices, and • documenting the aging effects of polymeric materials (i.e., encapsulation, backsheet).…”

Section: Mobile Devices For Onsite Usementioning

confidence: 99%

“…Consequently, IR-spectra can only be recorded of accessible materials, e.g., surfaces of backsheets or frontsheets. Whereas reflection measurements in the MIR region only have an analytical depth of 1-2 µm (surface sensitive measurement) [15], NIR has a much higher penetration depth of several millimeters in polymeric materials [18,23]. Thus, the recorded spectra can contain spectroscopic information of several thin layers of a multilayer foil (e.g., a backsheet).…”

Section: Detectable Sample Volume/penetration Depthmentioning

confidence: 99%

On-Site Identification of the Material Composition of PV Modules with Mobile Spectroscopic Devices

et al. 2020

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With the increased development of portable and handheld molecular spectrometers within recent years, new fields of applications have opened up, such as their use (i) for material identification of samples contained in large and non-portable components and (ii) the detection of material degradation effects and failures directly in the plant. The usability and transferability of well-established analytical characterization techniques, such as attenuated total reflection (ATR) Infrared (IR)-, Raman, and Near-Infrared (NIR)-spectroscopy as mobile devices for the in-field characterization of Photovoltaic (PV) modules, are described and discussed. Material identification of the polymeric compounds incorporated in the PV modules (encapsulants, backsheets) is often an important task, especially when degradation and failures occur. Whereas the knowledge of the bill of materials is one challenge, the detection of material degradation effects is another important issue. Both tasks can be solved nondestructively by the application of mobile spectrometers. Raman spectroscopy is the best-suited method for the identification of the encapsulant within the module (measurement through 3-mm glass), while NIR measurements allowed for the nondestructive determination of the composition of the multilayer backsheet. Surface degradation effects (e.g., oxidation, hydrolysis) are best detectable with IR-spectroscopy. The application of mobile devices allows for direct material analysis in the field without dismantling PV modules, transporting them to the lab, cutting them in smaller pieces, and analyzing them in conventional bench-top spectrometers.

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Nondestructive estimation of strength deterioration in photovoltaic backsheets using a portable near infrared spectrometer

Cited by 22 publications

References 11 publications

Depth profiling of degradation of multilayer photovoltaic backsheets after accelerated laboratory weathering: Cross-sectional Raman imaging

Depth profiling of degradation of multilayer photovoltaic backsheets after accelerated laboratory weathering: Cross-sectional Raman imaging

Manufacturing metrology for c-Si module reliability and durability Part III: Module manufacturing

On-Site Identification of the Material Composition of PV Modules with Mobile Spectroscopic Devices

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