Non-destructive determination of the degree of cross-linking of EVA solar module encapsulation Using DMA shear measurements

Mickiewicz, Rafal A.; Cahill, Ed; Wu, Po-I

doi:10.1109/pvsc.2012.6317707

Cited by 9 publications

(4 citation statements)

References 5 publications

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“…Subsequently Mickiewicz et al . reported a correlation of shear storage modulus at 100 °C and gel content for EVA foils . In technical literature, Hidalgo et al .…”

Section: Resultsmentioning

confidence: 95%

Correlation of spatially resolved photoluminescence and viscoelastic mechanical properties of encapsulating EVA in differently aged PV modules

Schlothauer

Grabmayer

Wallner

et al. 2016

Progress in Photovoltaics

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The photoluminescence of ethylene vinyl acetate (EVA) in aged photovoltaic modules shows specific spatial patterns on the scale of the cells in the module that depend on the aging conditions. It is the aim of this work to investigate the correlation of these photoluminescence patterns to the viscoelastic mechanical properties of the encapsulating EVA.For this, the degradation under various conditions of two specimen sets of polycrystalline silicon photovoltaic minimodules, comprising EVA as encapsulating polymer, is investigated using spatially resolved, ultraviolet-excited photoluminescence. Samples of the encapsulation EVA are systematically extracted from the modules for spatially resolved dynamic mechanical characterization.A correlation between the spatial distribution of the photoluminescence intensity and the values of storage modulus and loss factor of the EVA is found. An increase in the values for storage modulus and a decrease of the loss factor of the EVA from the edge of the cell towards the center are observed for all samples. We conclude that diffusion-limited oxidation must be considered for aging studies of the encapsulation EVA and that photoluminescence detection can reveal the scale on which such diffusion processes occur.

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“…Subsequently Mickiewicz et al . reported a correlation of shear storage modulus at 100 °C and gel content for EVA foils . In technical literature, Hidalgo et al .…”

Section: Resultsmentioning

confidence: 95%

Correlation of spatially resolved photoluminescence and viscoelastic mechanical properties of encapsulating EVA in differently aged PV modules

Schlothauer

Grabmayer

Wallner

et al. 2016

Progress in Photovoltaics

View full text Add to dashboard Cite

show abstract

“…During the last years, several investigations on the crosslinking behavior of EVA have been published . Most of these publications deal with the question how to characterize the degree of crosslinking.…”

Section: Introductionmentioning

confidence: 99%

“…Most of these publications deal with the question how to characterize the degree of crosslinking. Next to Soxhlet extraction, mostly thermal and thermomechanical characterization methods were used, but recently also optical or spectroscopic methods based on Raman, luminescence spectroscopy or white‐light interferometry have been applied and proven successful . These methods can not only be applied to isolated EVA films but also to EVA laminated within PV modules allowing for an in‐line quality control of the degree of crosslinking.…”

Section: Introductionmentioning

confidence: 99%

Crosslinking and post‐crosslinking of ethylene vinyl acetate in photovoltaic modules

Oreški

Rauschenbach

Hirschl

et al. 2017

J of Applied Polymer Sci

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Ethylene vinyl acetate (EVA) is the dominating material for the encapsulation of solar cells. A better understanding of the crosslinking reaction progress during PV module lamination could lead to promising approaches for shortening of PV module lamination times but also for optimization of the EVA formulation. Therefore, the main aim of this study is to investigate the crosslinking behavior of EVA but also for optimization potentials of the EVA formulation. Currently, a degree of crosslinking higher than 70% obtained from Soxhlet extraction, is used as quality control standard in PV industry. Thermomechanical properties of the investigated EVA films demonstrate a sufficient state of crosslinking already after 5 min, which corresponds to a Soxhlet value of around 50%. Nevertheless, the effect of the remaining, still reactive peroxide crosslinker under service relevant conditions cannot be neglected. Therefore, the behavior of mini‐modules manufactured at different lamination times and stored under various aging conditions is investigated. EVA not fully cured during lamination are undergoing postlamination crosslinking. At the same time, remaining active crosslinker causes discoloration at soldering ribbons after accelerated aging. The crosslinking time in the lamination process may be reduced to ≥6 min, compromising between high throughput in production and the need of avoiding degradation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44912.

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“…Proposed techniques like Raman spectroscopy [11], scanning acoustic microscopy [12], differential scanning calorimetry (DSC) [13], [14], dynamic mechanical analysis (DMA) [15], [16], tensile test [11], etc. In [11], the performances of those proposed techniques have been compared and evaluated comprehensively.…”

Section: Introductionmentioning

confidence: 99%

Fast and Nondestructive Detection on the EVA Gel Content in Photovoltaic Modules by Optical Reflection

Luo²,

Ballif

et al. 2015

IEEE J. Photovoltaics

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Abstract-Poly(ethylene-co-vinyl acetate) (EVA) has been the dominating material in the photovoltaic (PV) encapsulant market for decades, owing to its superior cost-performance balance. To achieve its desired material properties, EVA undergoes a curing reaction during the module encapsulation process. The resulting EVA gel content after encapsulation is an important criterion for the module encapsulation quality control. Normally, the determination of gel content is achieved using a tedious solvent extraction method. In this paper, a fast and nondestructive detection method on the EVA gel content based on the optical reflection is explored. First, the homogeneity of the EVA gel content distribution after the standard EVA encapsulation process is studied. Then, the feasibility of the proposed optical approach applied to transparent modules is investigated. After that, a method is developed to apply it to opaque modules by incorporating a mirror into the module construction. It was found that the haze factor of the reflected light correlates well with the EVA gel content in the opaque modules. This proof-of-concept work could lead to the development of a fast and nondestructive tool for detecting the EVA gel content in both transparent and opaque PV modules, which is promising for integration as an inline diagnostic tool in the module manufacturing line.

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Non-destructive determination of the degree of cross-linking of EVA solar module encapsulation Using DMA shear measurements

Cited by 9 publications

References 5 publications

Correlation of spatially resolved photoluminescence and viscoelastic mechanical properties of encapsulating EVA in differently aged PV modules

Correlation of spatially resolved photoluminescence and viscoelastic mechanical properties of encapsulating EVA in differently aged PV modules

Crosslinking and post‐crosslinking of ethylene vinyl acetate in photovoltaic modules

Fast and Nondestructive Detection on the EVA Gel Content in Photovoltaic Modules by Optical Reflection

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