Non-destructive 2D-luminescence detection of EVA in aged PV modules: Correlation to calorimetric properties, additive distribution and a clue to aging parameters

Schlothauer, Jan C.; Grabmayer, Klemens; Hintersteiner, Ingrid; Wallner, Gernot M.; Röder, Beate

doi:10.1016/j.solmat.2016.09.011

Cited by 33 publications

(23 citation statements)

References 60 publications

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“…Our own results as well as detailed studies by Schlothauer et al [47,49] confirm that in the photobleached areas, the polymeric encapsulant is chemically changed due to the oxidative reaction of the polymer, leading to chain scission and consequently, to changes in the viscoelastic mechanical properties and thermomechanical properties of the polymer.…”

Section: Discussionsupporting

confidence: 79%

“…The EVA polymer itself has no fluorescing groups in its original state but UV-excitable fluorophores/chromophores can be formed from the peroxidic curing agent/crosslinker during curing, either as decomposition product [29] or by degradation of stabilizers by peroxides [44,45]. Furthermore, constituents of the encapsulating material, like impurities or additives, also influence the UV-F of the encapsulating polymer [46][47][48]. With an increasing lifetime, the encapsulant material degraded due to the interaction with irradiation through artificial or natural sunlight and the elevated temperature from forming fluorophores.…”

Section: Discussionmentioning

confidence: 99%

“…Bleaching needs irradiation besides oxygen ("photobleaching") [11,29,30]. The width of the bleached rim around the cell and the bleached area above the cell crack increased with time and were correlated with the permeation rate of oxygen into the front encapsulant [47,50,51].…”

Section: Discussionmentioning

confidence: 99%

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Non-Destructive Failure Detection and Visualization of Artificially and Naturally Aged PV Modules

et al. 2018

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Several series of six-cell photovoltaic test-modules-intact and with deliberately generated failures (micro-cracks, cell cracks, glass breakage and connection defects)-were artificially and naturally aged. They were exposed to various stress conditions (temperature, humidity and irradiation) in different climate chambers in order to identify (i) the stress-induced effects; (ii) the potential propagation of the failures and (iii) their influence on the performance. For comparison, one set of test-modules was also aged in an outdoor test site. All photovoltaic (PV) modules were thoroughly electrically characterized by electroluminescence and performance measurements before and after the accelerated ageing and the outdoor test. In addition, the formation of fluorescence effects in the encapsulation of the test modules in the course of the accelerated ageing tests was followed over time using UV-fluorescence imaging measurements. It was found that the performance of PV test modules with mechanical module failures was rather unaffected upon storage under various stress conditions. However, numerous micro-cracks led to a higher rate of degradation. The polymeric encapsulate of the PV modules showed the build-up of distinctive fluorescence effects with increasing lifetime as the encapsulant material degraded under the influence of climatic stress factors (mainly irradiation by sunlight and elevated temperature) by forming fluorophores. The induction period for the fluorescence effects of the polymeric encapsulant to be detectable was~1 year of outdoor weathering (in middle Europe) and 300 h of artificial irradiation (with 1000 W/m 2 artificial sunlight 300-2500 nm). In the presence of irradiation, oxygen-which permeated into the module through the polymeric backsheet-bleached the fluorescence of the encapsulant top layer between the cells, above cell cracks and micro-cracks. Thus, UV-F imaging is a perfect tool for on-site detection of module failures connected with a mechanical rupture of solar cells.

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

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Non-Destructive Failure Detection and Visualization of Artificially and Naturally Aged PV Modules

et al. 2018

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“…Physical processes have similar effects to the ones due to annealing at high temperatures, changes in melting temperature and enthalpy might occur and are visible in the first heating curve. No reversible effects of physical ageing can be seen in the second heating curve [ 27 , 37 , 38 ].…”

Section: Resultsmentioning

confidence: 99%

“…This is a typical effect that can occur when the annealing (ageing) temperature lies within the melting region. During the exposure in the test chamber at 60 °C, smaller crystals with thinner lamellae can melt and crystallize again to form more perfect crystals with thicker lamellae, which melt at higher temperatures [ 27 , 37 ]. Additionally, in the last two steps of the UV test, it is possible to notice a shift of the melting temperature visible in the second heating run of the DSC measurement from 66 °C to 68 °C and finally to 86 °C, which is an indicator for the occurrence of deacetylation reaction [ 18 , 39 ].…”

Section: Resultsmentioning

confidence: 99%

Comparison of Degradation Behavior of Newly Developed Encapsulation Materials for Photovoltaic Applications under Different Artificial Ageing Tests

et al. 2021

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The main focus of this work is to investigate the degradation behavior of two newly developed encapsulants for photovoltaic applications (thermoplastic polyolefin (TPO) and polyolefin elastomer (POE)), compared to the most widely used Ethylene Vinyl Acetate (EVA) upon exposure to two different artificial ageing tests (with and without ultraviolet (UV) irradiation). Additive composition, optical and thermal properties and chemical structure (investigated by means of Thermal Desorption Gas Chromatography coupled to Mass Spectrometry, UV-Visible-Near Infrared spectroscopy, Differential Scanning Calorimetry, Thermogravimetric Analysis and Fourier Transform-Infrared spectroscopy, respectively) of the analyzed polymers were monitored throughout the exposure to artificial ageing tests. Relevant signs of photo-oxidation were detectable for TPO after the UV test, as well as a depletion of material’s stabilizers. Signs of degradation for EVA and POE were detected when the UV dose applied was equal to 200 kW h m−2. A novel approach is presented to derive information of oxidation induction time/dose from thermogravimetric measurements that correlate well with results obtained by using oxidation indices.

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An insight into a combined effect of backsheet and EVA encapsulant on field degradation of PV modules

Buerhop,

Pickel,

Stroyuk

et al. 2023

Energy Science & Engineering

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Polymer components, in particular, backsheets (BSs) and ethylene‐vinyl acetate (EVA) encapsulants, play a crucial role in the degradation of commercial silicon photovoltaic (PV) modules. Degradation mechanisms depend in a complex way on the composition and properties of all involved polymers. In this study, we demonstrate that differences in the composition of EVA encapsulants, in particular, the presence of additives, such as UV blockers, affect the degradative processes in a decisive way, even for modules with identical BSs. A combination of spectral, imaging, and electrical characterization techniques applied in a mixed lab/field study showed that the field aging of PV modules with the same BSs and different encapsulant components results in the development of different degradation signs, such as insulation resistance loss, corrosion of metal interconnects, water ingress, oxidation depth in the encapsulant, and potential‐induced degradation, depending on the presence of additives in the encapsulant. The present study provides an outlook on the complex influence of polymer components on the lifetime and performance of silicon PV modules.

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Non-destructive 2D-luminescence detection of EVA in aged PV modules: Correlation to calorimetric properties, additive distribution and a clue to aging parameters

Cited by 33 publications

References 60 publications

Non-Destructive Failure Detection and Visualization of Artificially and Naturally Aged PV Modules

Non-Destructive Failure Detection and Visualization of Artificially and Naturally Aged PV Modules

Comparison of Degradation Behavior of Newly Developed Encapsulation Materials for Photovoltaic Applications under Different Artificial Ageing Tests

An insight into a combined effect of backsheet and EVA encapsulant on field degradation of PV modules

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