Kinetics of degradation-induced photoluminescence in ethylene-vinyl-acetate as used in photovoltaic modules

Steffen, Ronald; Akraa, Mohammed; Röder, Beate

doi:10.1016/j.solmat.2019.110294

Cited by 4 publications

(4 citation statements)

References 39 publications

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“…The rate is reported, the increasing vinyl acetate content in the EVA leads to more EVA thermal degradation (8). It is found (9), that the optimization and characterization of the EVA are possible by the utilization of the degradation-induced the photoluminescence of the copolymer.…”

Section: Introductionmentioning

confidence: 89%

Spectroscopy Characterization of Ethylene Vinyl Acetate Degradation by Different Kinds of Accelerated Aging

2020

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This paper presents a sight about the chemical structure deformation of poly (ethylene-co-vinyl acetate) (EVA) samples according to the change ratio of rate constant values. Spectroscopy kinetics fluorescence curves are fitted for two characteristic wavelength domains of fluorescent intensities. The short wavelengths (320-400 nm) domain show spectra overlapping, while at long wavelengths (400-800 nm) domain spectra are arranged in regular for each specific accelerated aging time. The ratio of kinetics rate constant at long wavelengths to kinetics rate constant of short wavelengths is the criterion of the degree chemical structure deformation. Molar extrinsic coefficient relies on the chemical structure change. Through absorbance measurement, EVA samples have been classified into two groups. Presence of Cyasorb additive is the key point of the ranking. The effect of three different accelerated aging of dry (115 oC), damp (85% moisture, 85 oC), and irradiated (UV, 65 oC) aging have been considered for two samples of each group over different aging time. Spectroscopy of absorbance and fluorescent for aged samples have been discussed. In general, Cyasorb adding causes higher chemical structure deformation for the EVA sample. The most effective factor is the damp aging and the less one is the UV irradiation aging, while the biggest chemical structure change of Cyasorb-free sample is produced by damp aging and the less by dry heat.

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Section: Introductionmentioning

confidence: 89%

Spectroscopy Characterization of Ethylene Vinyl Acetate Degradation by Different Kinds of Accelerated Aging

2020

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“…With increasing lifetime (natural weathering) or storage time in a climate chamber (accelerated aging), the encapsulant material changes/ages due to the impact of climatic stresses À mainly temperature, irradiation and water vapour. Besides the architecture and bill of material of the PV-module e.g., permeability of the backside (glass, polymeric backsheets) and type of encapsulant [19], the resulting UVF pattern is mainly dependent on the exposure time and the stress factors applied [11,15,20,21].…”

Section: Introductionmentioning

confidence: 99%

Advanced UV-fluorescence image analysis for early detection of PV-power degradation

et al. 2023

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Reliability and durability of photovoltaic modules are a key factor for the development of emerging PV markets worldwide. Reliability is directly dependent on the chemical and physical stability of the polymeric encapsulation materials. One method capable of detecting ageing effects of the polymeric encapsulant directly on-site is UltraViolet Fluorescence (UVF) imaging. This work deals with advanced imaging analysis of UVF images and the subsequent correlation to electrical parameters of PV modules, which were exposed to climate-specific, long-term, accelerated aging procedures. For establishing a correlation, a so called UVF area ratio was established, resulting from the typical fluorescence patterns of the encapsulant material, which arise due to stress impact (e.g., water vapor ingress, elevated temperature, irradiation) and aging/degradation processes. Results of the data analysis show a clear correlation of the UVF area ratios and the electrical parameters with increasing aging time. In particular, the relationship between power and series resistance could be confirmed by extensive long-term test series with different climate-specific aging processes. Assuming the same type of polymeric encapsulation and backsheet and a comparable climate, determining the UVF area ratio can be used to estimate the service life and electrical power dissipation of each module installed in a PV array.

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“…As a result, the macromolecular changes lead to the deterioration of optical properties of the EVA layers, such as browning-yellowing and snail trails. 26,27 Besides, the permeability of the EVA layer to acidic products and moisture induces the oxidation of grid lines deposited on the surface of silicon cells, as well as adhesion and sealing degradation. 17,28,29 Previous investigations on chemical reactions in EVA have been reported in the literature, including both experiments 30,31 and computational modeling.…”

Section: Introductionmentioning

confidence: 99%

“…The typical degradation of polymer chains composing the encapsulant EVA layer involves the loss of small molecules, such as acetic acid and protons, and consequent failure at the macromolecular level. As a result, the macromolecular changes lead to the deterioration of optical properties of the EVA layers, such as browning‐yellowing and snail trails 26,27 . Besides, the permeability of the EVA layer to acidic products and moisture induces the oxidation of grid lines deposited on the surface of silicon cells, as well as adhesion and sealing degradation 17,28,29 .…”

Section: Introductionmentioning

confidence: 99%

A multifield coupled thermo‐chemo‐mechanical theory for the reaction‐diffusion modeling in photovoltaics

Liu

Lenarda

Reinoso

et al. 2023

Numerical Meth Engineering

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A comprehensive coupled thermo-chemo-mechanical modeling framework is proposed in this work to study the reaction-diffusion phenomena taking place inside photovoltaics (PV). When exposed to hygrothermal conditions, the encapsulant ethylene-co-vinyl acetate (EVA) layers undergo chemical degradation that significantly influences the overall PV performance. Aiming at efficient thermo-mechanical modeling, the coupled displacement-temperature governing equations for the EVA layers are formulated, and its 3D finite element (FE) implementation is derived in detail. Subsequently, the chemical reaction-diffusion processes occurring in the EVA layers are described, and the corresponding numerical implementation is formulated with the consideration of spatial and temporal variation of diffusivity and chemical kinetic rates. Specifically, the thermo-mechanical solution accounting for the heat generation from chemical reactions is projected to the FE model of the reaction-diffusion system in order to determine the kinetic rates and diffusion coefficients for its subsequent analysis. The proposed modeling method is applied to simulate the evolution of reaction-diffusion species at different damp heat tests, and predictions show a very satisfactory agreement with the analytical solution and experimental electroluminescence images taken from the literature. Its capabilities to predict the spatio-temporal variation are demonstrated through the simulation of the humidity freeze test, where the cyclic temperature boundary condition is imposed. With this modeling framework, it is possible to evaluate the degradation of PV modules under varying environmental boundary conditions, thus providing a guideline to design new products tailored for specific climatic zones.

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Kinetics of degradation-induced photoluminescence in ethylene-vinyl-acetate as used in photovoltaic modules

Cited by 4 publications

References 39 publications

Spectroscopy Characterization of Ethylene Vinyl Acetate Degradation by Different Kinds of Accelerated Aging

Spectroscopy Characterization of Ethylene Vinyl Acetate Degradation by Different Kinds of Accelerated Aging

Advanced UV-fluorescence image analysis for early detection of PV-power degradation

A multifield coupled thermo‐chemo‐mechanical theory for the reaction‐diffusion modeling in photovoltaics

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