scholarly journals Effect of Backsheet Properties on PV Encapsulant Degradation during Combined Accelerated Aging Tests

2020 ◽  
Vol 12 (12) ◽  
pp. 5208
Author(s):  
Djamel Eddine Mansour ◽  
Chiara Barretta ◽  
Luciana Pitta Bauermann ◽  
Gernot Oreski ◽  
Andreas Schueler ◽  
...  
Keyword(s):  
Transmission Rate ◽  
Heat Exposure ◽  
Accelerated Aging ◽  
Chemical Characterization ◽  
Ethylene Vinyl Acetate ◽  
Stress Factors ◽  
Oxygen Transmission Rate ◽  
Pv Module ◽  
Permeation Properties

Long-term photovoltaic (PV) module reliability is highly determined by the durability of the polymeric components (backsheet and encapsulation materials). This paper presents the result of experiments on encapsulant degradation influenced by the backsheet permeation properties. Towards this goal, one type of ethylene/vinyl acetate copolymer (EVA) was aged in glass/EVA/backsheet laminates in accelerated aging tests (up to 4000 h for Damp-Heat (DH) and up to 480 kWh/m2 for UV and UV-DH combined). The samples contained three backsheets with different permeation properties to examine their impact on EVA degradation. Thermal and chemical characterization shows that the EVA degradation is stronger with the glass–EVA–polyamide (PA)-based backsheet than with the polyethylene terephthalate (PET)-based backsheets. The higher oxygen transmission rate (OTR) of the PA-based backsheet may increase photo-oxidation and aggravating the degradation of EVA in the laminates. Furthermore, FTIR results were used to demonstrate the effect of damp heat exposure on the EVA interfaces, showing an accelerated degradation at the glass–EVA interface. The comparison of accelerated aging stress factors reveals that EVA suffers the strongest chemical and optical degradation when high UV, high temperature and high relative humidity are combined simultaneously.

PV Module Technology and Reliability – Status and Perspectives

Green ◽  
2012 ◽  
Vol 2 (4) ◽  
Author(s):  
Wirth Harry ◽  
Ferrara Claudio
Keyword(s):  
Accelerated Aging ◽  
Stress Factors ◽  
Test Results ◽  
Certification Testing ◽  
Pv Module ◽  
Type Approval ◽  
Laboratory Results ◽  
The Common ◽  
Module Efficiency ◽  
Product Costs

AbstractSolar cell processing into modules is mostly responsible for the product's reliability, has a severe impact on product costs and controls 10–15% of its efficiency. This article gives an overview on current module technology and highlights innovative approaches to reduce material cost and increase module efficiency. High potential approaches like back contact technology are those that simultaneously address cell and module technology to offer efficiency gains in the range of 10%.Module reliability expectations of 25 years or more require quality assurance beyond the common type approval standards. In its second part, the article addresses stress factors for PV modules. To ensure fast innovation cycles, accelerated aging tests are used to reproduce these stress factors in the laboratory. Results from certification testing are discussed as well as new approaches for improved testing. More realistic test results can be obtained by simulating combinations of stress factors.

scholarly journals Evaluarea potenţialului de păstrare a seminţelor mostrelor din colecţia de Triticum durum L.

2021 ◽  
Author(s):  
Lolita Melian ◽  
◽  
Liudmila Corlateanu ◽  
Victoria Mihailă ◽  
Doina Cutitaru ◽  
...  
Keyword(s):  
Durum Wheat ◽  
Triticum Durum ◽  
Accelerated Aging ◽  
Gene Bank ◽  
Stress Factors ◽  
Long Term Storage ◽  
Dry Biomass ◽  
Seedling Roots ◽  
Term Storage

The test of accelerated aging of seeds (AAS) was applied on 7 genotypes of durum wheat, and the morphophysiological parameters of seeds and seedlings, such as dynamics of seed germination, length of seedling roots, fresh and dry biomass of seedlings, were investigated. The genotypic features of collection samples of durum wheat were identified after exposure to stress factors (high temperature and humidity). Such a grouping of genotypes according to their potential ability to preserve the viability of seeds is an important complex characteristic of collection samples when they are placed for long-term storage in a plant gene bank.

scholarly journals Impact of Permeation Properties and Backsheet-Encapsulant Interactions on the Reliability of PV Modules

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Cornelia Peike ◽  
Philip Hülsmann ◽  
Matthias Blüml ◽  
Philipp Schmid ◽  
Karl-Anders Weiß ◽  
...  
Keyword(s):  
Water Vapor ◽  
Sheet Material ◽  
Accelerated Aging ◽  
Water Vapor Permeability ◽  
Ethylene Vinyl Acetate ◽  
Polyvinyl Butyral ◽  
Clear Correlation ◽  
Vapor Permeability ◽  
Sheet Materials ◽  
Permeation Properties

The reliability of photovoltaic modules is highly influenced by the material properties of the backsheet and encapsulation material. Currently, little attention is paid to the permeation properties of the back-sheet material or to its impact on encapsulation degradation and module reliability. We investigated the interaction of different types of solar encapsulation and back-sheet materials. Therefore, various laminates were made to examine the environmental impact on such materials during the aging processes. One focus of our study lies in oxygen and water vapor permeability of the back-sheet materials. The encapsulants used were an ethylene vinyl acetate (EVA), a TPSE (thermoplastic silicone elastomer), an ionomer, and a PVB (polyvinyl butyral). Back-sheet materials were a TPT (Tedlar-PET-Tedlar) foil, a polyamide (PA) sheet and a polyethylene terephthalate (PET) composite film. Raman spectroscopic and FT-IR/vis-reflectance measurements were carried out before and after different accelerated aging procedures. The water vapor and oxygen permeation properties were measured. A clear correlation between the permeation properties and the observed aging behavior was found. The degradation, especially of the encapsulant, resulted in increased fluorescence background in the Raman spectra. It could be shown that the encapsulation-cell-backsheet system should be optimized in order to minimize the stress on the PV-module components.

Impact of Permeation Properties and Back Sheet/ Encapsulation Interactions on the Reliability of PV Modules

2011 ◽  
Author(s):  
Philip Hu¨lsmann ◽  
Cornelia Peike ◽  
Matthias Blu¨ml ◽  
Philipp Schmid ◽  
Karl-Anders Weiß ◽  
...  
Keyword(s):  
Accelerated Aging ◽  
Clear Correlation ◽  
Pv Module ◽  
Pv Modules ◽  
Different Types ◽  
Before And After ◽  
Ft Ir ◽  
Permeation Properties ◽  
Reflectance Measurements ◽  
Made In

The interaction of different types of new encapsulation and back sheet materials for PV modules was investigated. Therefore, various types of laminates were made in order to examine the environmental impact on such materials during the materials aging process with special attention to the permeability of the back sheet. The laminates were characterized by Raman Spectroscopy, FT-IR/VIS reflectance measurements before and after different accelerated aging procedures. The water vapor and oxygen permeation properties were measured. A clear correlation between the permeation properties and the observed aging behavior was found. The degradation, especially of the encapsulant, resulted in increasing background fluorescence in the Raman Spectra and in a change of transmittance of the encapsulants which is also known as yellowing. It could be shown that the encapsulation/cell/back-sheet system should be optimized in order to minimize the stress on the PV-module components.

Strategies to Protect Hematopoietic Stem Cells from Culture-Induced Stress Conditions

2020 ◽  
Vol 15 ◽  
Author(s):  
Fatima Aerts-Kaya
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Ex Vivo ◽  
Stress Conditions ◽  
Stress Factors ◽  
Hematopoietic Stem ◽  
Induced Stress

: In contrast to their almost unlimited potential for expansion in vivo and despite years of dedicated research and optimization of expansion protocols, the expansion of Hematopoietic Stem Cells (HSCs) in vitro remains remarkably limited. Increased understanding of the mechanisms that are involved in maintenance, expansion and differentiation of HSCs will enable the development of better protocols for expansion of HSCs. This will allow procurement of HSCs with long-term engraftment potential and a better understanding of the effects of the external influences in and on the hematopoietic niche that may affect HSC function. During collection and culture of HSCs, the cells are exposed to suboptimal conditions that may induce different levels of stress and ultimately affect their self-renewal, differentiation and long-term engraftment potential. Some of these stress factors include normoxia, oxidative stress, extra-physiologic oxygen shock/stress (EPHOSS), endoplasmic reticulum (ER) stress, replicative stress, and stress related to DNA damage. Coping with these stress factors may help reduce the negative effects of cell culture on HSC potential, provide a better understanding of the true impact of certain treatments in the absence of confounding stress factors. This may facilitate the development of better ex vivo expansion protocols of HSCs with long-term engraftment potential without induction of stem cell exhaustion by cellular senescence or loss of cell viability. This review summarizes some of available strategies that may be used to protect HSCs from culture-induced stress conditions.

A NEW TEST METHOD FOR SHIPPING PALLETS OF SOLAR PRODUCTS

2016 ◽  
Vol 40 (4) ◽  
pp. 481-489
Author(s):  
Shu-Tsung Hsu ◽  
Yean-San Long ◽  
Teng-Chun Wu
Keyword(s):  
Yield Loss ◽  
Test Method ◽  
Package Design ◽  
Rate Analysis ◽  
Energy Demands ◽  
Pv Module ◽  
Cell Module ◽  
Solar Cell Module ◽  
Module System

The photovoltaic (PV) industry is expanding rapidly to meet the growing renewable-energy demands globally. The failure-rate analysis indicated that a large portion of the accelerated PV module qualification failures were related to the failure of PV cell itself, which was leading to the yield loss of PV products during shipping or transportation. Therefore, the damaged cell (or module) caused by shipping is always one of the serious problems to impact the long-term reliability of PV product. This paper aims to propose a new test method of reliability evaluation for shipping pallet of solar product. The first scenario is the test pallet shipped in fab (e.g., fork-lift truck or hand-pallet truck). The second scenario is the test pallet transported from fab to fab by different vehicle (e.g., truck, train, aircraft, and shipboard). Consequently, detailed results were applied to SEMI Doc. 5431 and released as SEMI PV56-1214 by voting in December 2014. The solar cell/module/system makers and buyers, or any other party interested like package design, can thus have a common document to refer to when desired.

scholarly journals High-efficiency CO2 separation using hybrid LDH-polymer membranes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaozhi Xu ◽  
Jiajie Wang ◽  
Awu Zhou ◽  
Siyuan Dong ◽  
Kaiqiang Shi ◽  
...  
Keyword(s):  
Self Assembly ◽  
High Efficiency ◽  
Transmission Rate ◽  
Spray Coating ◽  
Separation Performance ◽  
Pdms Layer ◽  
Operational Testing ◽  
Enhanced Solubility ◽  
Double Hydroxide

AbstractMembrane-based gas separation exhibits many advantages over other conventional techniques; however, the construction of membranes with simultaneous high selectivity and permeability remains a major challenge. Herein, (LDH/FAS)n-PDMS hybrid membranes, containing two-dimensional sub-nanometre channels were fabricated via self-assembly of unilamellar layered double hydroxide (LDH) nanosheets and formamidine sulfinic acid (FAS), followed by spray-coating with a poly(dimethylsiloxane) (PDMS) layer. A CO2 transmission rate for (LDH/FAS)25-PDMS of 7748 GPU together with CO2 selectivity factors (SF) for SF(CO2/H2), SF(CO2/N2) and SF(CO2/CH4) mixtures as high as 43, 86 and 62 respectively are observed. The CO2 permselectivity outperforms most reported systems and is higher than the Robeson or Freeman upper bound limits. These (LDH/FAS)n-PDMS membranes are both thermally and mechanically robust maintaining their highly selective CO2 separation performance during long-term operational testing. We believe this highly-efficient CO2 separation performance is based on the synergy of enhanced solubility, diffusivity and chemical affinity for CO2 in the sub-nanometre channels.

scholarly journals Impact of Backbone Amide Substitution at the Meta- and Para-Positions on the Gas Barrier Properties of Polyimide

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2097
Author(s):  
Qian Wen ◽  
Ao Tang ◽  
Chengliang Chen ◽  
Yiwu Liu ◽  
Chunguang Xiao ◽  
...  
Keyword(s):  
Transmission Rate ◽  
Barrier Properties ◽  
Polyimide Film ◽  
Flexible Display ◽  
Gas Barrier ◽  
Positron Annihilation Lifetime ◽  
Barrier Materials ◽  
Oxygen Transmission Rate ◽  
Display Technology ◽  
Gas Barrier Properties

This study designed and synthesised a meta-amide-substituted dianiline monomer (m-DABA) as a stereoisomer of DABA, a previously investigated para-amide-substituted dianiline monomer. This new monomer was polymerised with pyromellitic dianhydride (PMDA) to prepare a polyimide film (m-DABPI) in a process similar to that employed in a previous study. The relationship between the substitution positions on the monomer and the gas barrier properties of the polyimide film was investigated via molecular simulation, wide-angle X-ray diffraction (WXRD), and positron annihilation lifetime spectroscopy (PALS) to gain deeper insights into the gas barrier mechanism. The results showed that compared with the para-substituted DABPI, the m-DABPI exhibited better gas barrier properties, with a water vapour transmission rate (WVTR) and an oxygen transmission rate (OTR) as low as 2.8 g·m−2·d−1 and 3.3 cm3·m−2·d−1, respectively. This was because the meta-linked polyimide molecular chains were more tightly packed, leading to a smaller free volume and lower molecular chain mobility. These properties are not conducive to the permeation of small molecules into the film; thus, the gas barrier properties were improved. The findings have significant implications for the structural design of high-barrier materials and could promote the development of flexible display technology.

scholarly journals Tree Vitality and Forest Health: Can Tree-Ring Stable Isotopes Be Used as Indicators?

2021 ◽  
Author(s):  
Paolo Cherubini ◽  
Giovanna Battipaglia ◽  
John L. Innes
Keyword(s):  
Air Pollution ◽  
Stable Isotopes ◽  
Tree Ring ◽  
Forest Decline ◽  
Forest Health ◽  
Stress Factors ◽  
Tree Vitality ◽  
The Past ◽  
Physiological Processes

Abstract Purpose of Review Society is concerned about the long-term condition of the forests. Although a clear definition of forest health is still missing, to evaluate forest health, monitoring efforts in the past 40 years have concentrated on the assessment of tree vitality, trying to estimate tree photosynthesis rates and productivity. Used in monitoring forest decline in Central Europe since the 1980s, crown foliage transparency has been commonly believed to be the best indicator of tree condition in relation to air pollution, although annual variations appear more closely related to water stress. Although crown transparency is not a good indicator of tree photosynthesis rates, defoliation is still one of the most used indicators of tree vitality. Tree rings have been often used as indicators of past productivity. However, long-term tree growth trends are difficult to interpret because of sampling bias, and ring width patterns do not provide any information about tree physiological processes. Recent Findings In the past two decades, tree-ring stable isotopes have been used not only to reconstruct the impact of past climatic events, such as drought, but also in the study of forest decline induced by air pollution episodes, and other natural disturbances and environmental stress, such as pest outbreaks and wildfires. They have proven to be useful tools for understanding physiological processes and tree response to such stress factors. Summary Tree-ring stable isotopes integrate crown transpiration rates and photosynthesis rates and may enhance our understanding of tree vitality. They are promising indicators of tree vitality. We call for the use of tree-ring stable isotopes in future monitoring programmes.

Effects of Accelerated Aging Period of Time at 180°C on Tensile Property of Plain Woven Fabric/Epoxy Resin Laminated Composites

2012 ◽  
Vol 182-183 ◽  
pp. 76-79 ◽  
Author(s):  
Lei Lei Song ◽  
Quan Rong Liu ◽  
Jia Lu Li
Keyword(s):  
Tensile Strength ◽  
Carbon Fiber ◽  
Epoxy Resin ◽  
Laminated Composites ◽  
Accelerated Aging ◽  
Woven Fabric ◽  
Accelerated Ageing ◽  
Time Intervals ◽  
Composite Samples

In this paper, carbon fiber reinforced resin matrix composites were produced by stacking eight pieces of carbon fiber woven plain fabric and subjected to accelerated ageing. Accelerated ageing was carried out in oven at 180°C for three different time intervals (60 hours, 120 hours and 180 hours). The influence of different ageing time intervals at 180°C on tensile properties of laminated composites was examined, compared with the composites without aging. The appearance and damage forms of these laminated composites were investigated. The results revealed that the tensile strength of the laminates declined significantly after long term accelerated aging at 180°C. The average tensile strengths of composite samples aged 60 hours, 120 hours, and 180 hours period of time at 180°C are 80.36%, 79.82%, 76.57% of average tensile strength of composite samples without aging, respectively. The high temperature accelerated aging makes the resin macromolecular structure in the composites changed, and then the adhesive force between fiber bundles and resin declines rapidly which result in the tensile strength of composites aged decrease. This research provides a useful reference for long term durability of laminated/epoxy resin composites.

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