Determining the degree of crosslinking of ethylene vinyl acetate photovoltaic module encapsulants—A comparative study

Hirschl, Christina; Biebl–Rydlo, M.; DeBiasio, M.; Mühleisen, W.; Neumaier, Lukas; Scherf, Werner; Oreški, Gernot; Eder, Gabriele; Chernev, Boril Stefanov; Schwab, W; Kraft, Martin

doi:10.1016/j.solmat.2013.04.022

Cited by 183 publications

(172 citation statements)

References 17 publications

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“…The melting peaks observed at 110 and 127 C of samples B3 and B4 are attributed to the melting of the inner layers (see Figure 3). Crosslinked EVA commonly used as encapsulant for PV modules has a vinylacetate (VA) content of 30% (w/w) and melts in the temperature region between 30 and 70 C. 16 Therefore the first melting peak at The melting region of PET for all backsheets was found to be rather broad (230-270 C) but the maximum of the peak was constant in a very narrow temperature range between 256 and 258 C (standard deviation of each materials melting point smaller than 0.4 C). Semicrystalline polymers have more or less perfect crystallites with different lamellae thicknesses.…”

Section: Resultsmentioning

confidence: 99%

Degradation of photovoltaic backsheets: Comparison of the aging induced changes on module and component level

Knausz

Eder

Voronko

et al. 2015

J of Applied Polymer Sci

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In reliability testing of components for PV modules an always remaining question is about material (in)compatibilities and synergistic effects and thus, how results of singly tested materials correlate with materials aged within PV modules. Testing of single materials would simplify sample preparation, reduce costs and offer more testing options. Therefore the main objective of this study was to compare the aging behavior of single backsheets with that of backsheets incorporated within PV modules. Four different types of backsheets were chosen, all of them comprising of polyethylene terephthalate (PET) core layers, but differing outer protection layers. Test modules using identical components, varying only in the type of backsheet used were produced and damp heat aged (85 C/85% RH 2000 h). The results revealed no influence of the PV module lamination on the thermal characteristics of the polymeric backsheets. Even after DH aging, differences between single and module laminated backsheets were negligible. Degradation effects of PET could be detected for all aged sheets by thermal analysis and were confirmed by tensile tests and rheological measurements. Thus, it can be stated that testing of single PET based backsheets under DH aging conditions is a practicable way to investigate the applicability of a new backsheet.

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Section: Resultsmentioning

confidence: 99%

Degradation of photovoltaic backsheets: Comparison of the aging induced changes on module and component level

Knausz

Eder

Voronko

et al. 2015

J of Applied Polymer Sci

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“…It can be observed from Figure 4 that there are several transitions during heating of EVA containing curing agents. Two exothermic peaks appear in the region of 40-80°C, one of which at about 50°C is attributed to a secondary crystallization, whereas the peak around 65-70°C is the thermo-dynamical melting point of the PE crystallites of EVA [14][15][16]. The curing of EVA occurs in the region of 100-180°C by the emergence of a double exothermic peak.…”

Section: Resultsmentioning

confidence: 99%

Fast curing ethylene vinyl acetate films with dual curing agent towards application as encapsulation materials for photovoltaic modules

Xue¹,

Ruan²,

Zhang³

et al. 2014

Express Polym. Lett.

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Abstract. To speed up curing of ethylene vinyl acetate (EVA) films as encapsulation materials for photovoltaic modules, a dual curing agent of benzoyl peroxide (BPO) and butylperoxy 2-ethylhexyl carbonate (TBEC) was introduced in this work. The experimental results indicated that for the weight ratio of BPO/TBEC of 0.6/2.4, over 80% gel content of EVA was yielded after curing at 130°C for 12 min. Compared with the case of single curing agent, the present one obviously operated at much lower temperature with faster rate. By carefully studying the influence of curing agent proportion and curing conditions on gel content of EVA films, as well as rheology and curing kinetics, the mechanism involved was analyzed and verified. The results are believed to be useful for developing new curing system of EVA encapsulation films with improved processability.

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“…Several companies/institutes have also proposed other concepts based on different techniques [11], [19]. Compared to them, the advantages of the concept presented here are 1) high sensitivity in the range of high gel content (over 80%), 2) potentially applicable to both glass/glass and glass/backsheet PV modules, and 3) ideal for inline diagnosis thanks to its nondestructive nature and unrivaled detection speed (time needed can be well below 5 s).…”

Section: ) Optical Detection In Reflection Mode For Transparent Photmentioning

confidence: 99%

“…In the module manufacturing process, a number of modules have to be removed at a certain frequency for monitoring the EVA gel content inside. Historically, EVA gel content is measured by the solvent extraction method, where an organic solvent like toluene or xylene are used to dissolve the soluble portion and extract the cross-linked portion [10], [11]. The gel content is calculated as the weight percentage of the nonsoluble part of the EVA.…”

Section: Introductionmentioning

confidence: 99%

“…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. A few of them such as DSC and DMA remain to be destructive, although they can shorten time required per measurement.…”

Section: Introductionmentioning

confidence: 99%

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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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Determining the degree of crosslinking of ethylene vinyl acetate photovoltaic module encapsulants—A comparative study

Cited by 183 publications

References 17 publications

Degradation of photovoltaic backsheets: Comparison of the aging induced changes on module and component level

Degradation of photovoltaic backsheets: Comparison of the aging induced changes on module and component level

Fast curing ethylene vinyl acetate films with dual curing agent towards application as encapsulation materials for photovoltaic modules

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

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