Luminescence and absorption characterization of ethylene-vinyl acetate encapsulant for PV modules before and after weathering degradation

Pern, F. J.

doi:10.1016/0141-3910(93)90035-h

Cited by 74 publications

(46 citation statements)

References 19 publications

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“…Pern and Czanderna found [4,7] that the main reason for discoloration of EVA is the formation of polyconjugated C ¼C bonds (polyenes) by multistep deacetylation as well as the presence of a,b-unsaturated carbonyl groups. EVA undergoes a two-step thermal degradation with the formation of acetic acid when it is heated.…”

Section: Degradation Mechanisms Of Evamentioning

confidence: 98%

Non-destructive degradation analysis of encapsulants in PV modules by Raman Spectroscopy

Peike

Kaltenbach

Weiß

et al. 2011

Solar Energy Materials and Solar Cells

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Section: Degradation Mechanisms Of Evamentioning

confidence: 98%

Non-destructive degradation analysis of encapsulants in PV modules by Raman Spectroscopy

Peike

Kaltenbach

Weiß

et al. 2011

Solar Energy Materials and Solar Cells

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“…Regarding the mechanism enabling degradation, early work suggested the formation of long chains of conjugated unsaturated sequences (polyenes), generated by the photo‐induced deacetylation of vinyl acetate . Other studies focused on α‐ and β‐unsaturated structures present in the EVA resin that were speculated to contribute to UV degradation and discoloration . More recent studies, eg, instead identify that the degradation of EVA results from interactions between stabilization additives.…”

Section: Introductionmentioning

confidence: 99%

Degradation in photovoltaic encapsulant transmittance: Results of the first PVQAT TG5 artificial weathering study

Miller

Bokria²,

Burns

et al. 2019

Progress in Photovoltaics

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Reduced optical transmittance of encapsulants resulting from ultraviolet (UV) degradation is frequently identified as a cause of decreased performance through the service life of photovoltaic modules. However, the present module safety and qualification standards apply short UV doses, only capable of examining design robustness and “infant mortality” failures. Furthermore, essential information remains unknown that might be used to screen encapsulants through product lifetime. We conducted an interlaboratory study to provide the understanding that will be used toward developing a higher‐fidelity, more‐rigorous UV weathering test. Five representative known formulations of poly (ethylene‐co‐vinyl acetate) were studied, in addition to one thermoplastic polyurethane material. Replicate laminated silica/polymer/silica specimens were examined at seven institutions using a variety of indoor chambers (including xenon, UVA‐340, and metal‐halide light sources). Specimens were artificially weathered for 180 cumulative days at steady‐state accelerated test conditions, predesignated relative to the default irradiance of 1.0 W·m−2·nm−1 at 340 nm, chamber temperature of 60°C, and chamber relative humidity of 30%. The solar‐weighted transmittance, yellowness index, and the UV cut‐off wavelength—each determined from the measured hemispherical transmittance—are examined to provide understanding and guidance for the UV light source (type lamp and filters), temperature, and humidity used in accelerated UV aging tests. The relative efficacy of xenon‐arc and UVA‐340 fluorescent sources and the typical range of activation energy for degradation is quantified from the experiments.

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“…(In one prominent incident , however, the effect of reduced transmittance was much less significant than that related to damaged electrical connectivity at solder joints). Molecular cross‐linking (gel content) is increased as the result of artificial or field UV exposure , with a corresponding effect on the mechanical properties (decreased elastic modulus and reduced tensile strength ). Reference (where gel content was identified as steady) refutes these usual observations.…”

Section: Introductionmentioning

confidence: 99%

“…Reference (where gel content was identified as steady) refutes these usual observations. Acetic acid may form in EVA as a by‐product of degradation and act as a catalyst for further degradation . Metal/EVA interfaces were also speculated to catalyze the degradation of EVA, including interfaces with Ag, Cu, Sn, and Pb (common interconnect and solder materials) .…”

Section: Introductionmentioning

confidence: 99%

“…Metal/EVA interfaces were also speculated to catalyze the degradation of EVA, including interfaces with Ag, Cu, Sn, and Pb (common interconnect and solder materials) . A gridline‐shaped damage pattern may also result from increased optical damage, that is, light is reflected (and consequently concentrated) by the gridlines . A similar effect may be observed over tabbing or bus bars, but is less frequently mentioned.…”

Section: Introductionmentioning

confidence: 99%

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Durability of polymeric encapsulation materials for concentrating photovoltaic systems

Miller

Muller

Kempe

et al. 2012

Progress in Photovoltaics

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The durability of polymeric encapsulation materials was examined using outdoor exposure at the nominal optical concentration of 500 suns. The results for 12 months' cumulative field deployment are presented for materials including ethylene‐co‐vinyl acetate, polyvinyl butyral (PVB), ionomer, polyethylene/polyoctene copolymer, thermoplastic polyurethane, poly(dimethylsiloxane), and poly(phenyl‐methyl siloxane). Measurements during the experiment included optical transmittance (direct and hemispherical), mass, visual appearance, and fluorescence spectroscopy in addition to the initial thermogravimetry of the materials. Measurements of the field conditions and ultraviolet dose at the test site were facilitated by numerous laboratory instruments; characterization of the specimen temperature was performed using thermography. Discovery experiments identified the importance of a secondary homogenizer optic and the importance of contamination control. To date, the formal experiment verified a thermal‐runaway‐motivated combustion failure mechanism for one of the PVB formulations and identified densification, cracking, and haze‐formation behaviors in some of the silicone specimens. The behaviors observed for the silicone specimens may be facilitated by their greater thickness. Copyright © 2012 John Wiley & Sons, Ltd.

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Luminescence and absorption characterization of ethylene-vinyl acetate encapsulant for PV modules before and after weathering degradation

Cited by 74 publications

References 19 publications

Non-destructive degradation analysis of encapsulants in PV modules by Raman Spectroscopy

Non-destructive degradation analysis of encapsulants in PV modules by Raman Spectroscopy

Degradation in photovoltaic encapsulant transmittance: Results of the first PVQAT TG5 artificial weathering study

Durability of polymeric encapsulation materials for concentrating photovoltaic systems

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