The Experts below are selected from a list of 4197 Experts worldwide ranked by ideXlab platform

Christoph J Brabec - One of the best experts on this subject based on the ideXlab platform.

  • nondestructive characterization of polymeric components of silicon solar modules by near infrared absorption spectroscopy nira
    Solar Energy Materials and Solar Cells, 2020
    Co-Authors: Oleksandr Stroyuk, Claudia Buerhoplutz, Andreas Vetter, Jens Hauch, Christoph J Brabec
    Abstract:

    Abstract Degradation of the encapsulation of solar modules is a crucial problem and, accordingly, tools for assessing and understanding the according degradation is an important research topic. Here, we suggest near-infrared absorption spectroscopy (NIRA) as a tool that has a strong potential to determine non-invasively the composition of Encapsulant and backsheet in typical commercial solar modules. Correct polymer identification by NIRA was supported by Raman spectral microscopy of the backsheet air sides and cross sections, with a hundred solar modules of different manufacturers analyzed by both spectroscopic methods. Furthermore, a specific NIRA measurement regime of the ethylene vinyl acetate Encapsulant is presented, which potentially allows to probe the composition of the Encapsulant non-destructively under lab conditions but also on silicon solar modules in the field installed outdoors. The present report shows NIRA to be a powerful method for non-destructive analysis of backsheets and Encapsulants of photovoltaic silicon modules.

Susan Agro - One of the best experts on this subject based on the ideXlab platform.

  • investigation of the degradation and stabilization of eva based Encapsulant in field aged solar energy modules
    Polymer Degradation and Stability, 1997
    Co-Authors: Peter P Klemchuk, Myer Ezrin, Gary Lavigne, William Holley, James Galica, Susan Agro
    Abstract:

    Abstract The discoloration of EVA-based Encapsulant in some solar photovoltaic modules, most notably a mirror-enhanced module and others recovered from Carrisa Plains, CA, has been investigated in order to understand the causes of the phenomenon and to find solutions to the problem of reduced electrical output. The discoloration has been found to be due to interactions between cross-linking peroxide and some stabilizing additives, and is also likely to be due to oxidation of the Encapsulant. No evidence could be found in field-aged, discolored EVA Encapsulant for conjugated double bonds, which has been implicated as the cause of discoloration in earlier publications. Reformulated Encapsulant and the use of cerium-oxide-containing glass as the top cover of PV modules have dramatically reduced discoloration. Additional benefit should be derived by excluding oxygen from the modules.

  • investigation of the degradation and stabilization of eva based Encapsulant in field aged solar energy modules
    Polymer Degradation and Stability, 1997
    Co-Authors: Peter P Klemchuk, Myer Ezrin, Gary Lavigne, William Holley, James Galica, Susan Agro
    Abstract:

    Abstract The discoloration of EVA-based Encapsulant in some solar photovoltaic modules, most notably a mirror-enhanced module and others recovered from Carrisa Plains, CA, has been investigated in order to understand the causes of the phenomenon and to find solutions to the problem of reduced electrical output. The discoloration has been found to be due to interactions between cross-linking peroxide and some stabilizing additives, and is also likely to be due to oxidation of the Encapsulant. No evidence could be found in field-aged, discolored EVA Encapsulant for conjugated double bonds, which has been implicated as the cause of discoloration in earlier publications. Reformulated Encapsulant and the use of cerium-oxide-containing glass as the top cover of PV modules have dramatically reduced discoloration. Additional benefit should be derived by excluding oxygen from the modules.

K Agroui - One of the best experts on this subject based on the ideXlab platform.

  • determination of thermal properties of crosslinked eva Encapsulant material in outdoor exposure by tsc and dsc methods
    Renewable Energy, 2014
    Co-Authors: K Agroui, George Collins
    Abstract:

    Abstract Apart from chemical structure, thermal properties of polymers depend mainly on polymer morphology, which is affected by the processing conditions. Outdoor exposure of the materials leads to changes in polymer morphology. The main objective of this experimental investigation was to better understand the changes due to thermal transitions and the molecular organizations of the crosslinked EVA Encapsulant material after aging in outdoor exposure. The thermal properties of unaged and aged EVA Encapsulant material were measured by thermal analysis methods as TSC and DSC. For the aged EVA samples, the distinctive feature of these results is that there are two different endothermic processes due to the recrystallization phenomenon. Furthermore, the difference of the magnitude of peak current by TSC technique suggests increased crosslinking exposure occurring selectively in the high temperature phase as a result of outdoor exposure.

  • measurement of glass transition temperature of crosslinked eva Encapsulant by thermal analysis for photovoltaic application
    Renewable Energy, 2012
    Co-Authors: K Agroui, George Collins, J Farenc
    Abstract:

    The purpose of the experiment was to better understand the changes due to thermal transitions and the molecular organizations of EVA Encapsulant material after cross linking process by thermal analysis methods as DSC, TSC and DMTA. DSC experiments on EVA show a glass transition at about −33.1 °C, which is characteristic of crystalline phase and an endothermic peak at temperature of 55 °C characteristic of amorphous phase. The basic results by TSC technique is that there are two relaxations that are reproducibly observed in crosslinked EVA Encapsulant material. At temperature polarization 60 °C, a low temperature relaxation occurs at temperature −24.4 °C and a high temperature relaxation occurs at temperature +30.4 °C. DMTA results exhibit two tanδ peaks located at −14.9 °C and +66.6 °C. In addition, our results reveal that the glass transition temperature determined by TSC experiments in depolarization mode is more relevant than DSC and DMTA methods. TSC was chosen due to its low equivalent frequency consideration, useful to study Encapsulant material exhibiting multiple relaxations.

  • thermal stability of slow and fast cure eva Encapsulant material for photovoltaic module manufacturing process
    Solar Energy Materials and Solar Cells, 2006
    Co-Authors: K Agroui, A Maallemi, M Boumaour, George L Collins, M Salama
    Abstract:

    Ethylene vinyl acetate (EVA) is a copolymer Encapsulant used as an interlayer in the industrial photovoltaic module encapsulation process. EVA serves to provide the functions of structural support, electrical isolation, physical isolation/protection and thermal conduction for the solar cell circuit. This paper focuses on thermal properties of slow and fast cure EVA Encapsulant material. Phase transition and thermal stability parameters of uncured EVA materials have been studied by employing thermo gravimetric analysis, thermal differential analysis and differential scanning calorimetric. EVA fast cure Encapsulant material exhibits superior thermal stability in the range of operational cell temperature.

Peter P Klemchuk - One of the best experts on this subject based on the ideXlab platform.

  • investigation of the degradation and stabilization of eva based Encapsulant in field aged solar energy modules
    Polymer Degradation and Stability, 1997
    Co-Authors: Peter P Klemchuk, Myer Ezrin, Gary Lavigne, William Holley, James Galica, Susan Agro
    Abstract:

    Abstract The discoloration of EVA-based Encapsulant in some solar photovoltaic modules, most notably a mirror-enhanced module and others recovered from Carrisa Plains, CA, has been investigated in order to understand the causes of the phenomenon and to find solutions to the problem of reduced electrical output. The discoloration has been found to be due to interactions between cross-linking peroxide and some stabilizing additives, and is also likely to be due to oxidation of the Encapsulant. No evidence could be found in field-aged, discolored EVA Encapsulant for conjugated double bonds, which has been implicated as the cause of discoloration in earlier publications. Reformulated Encapsulant and the use of cerium-oxide-containing glass as the top cover of PV modules have dramatically reduced discoloration. Additional benefit should be derived by excluding oxygen from the modules.

  • investigation of the degradation and stabilization of eva based Encapsulant in field aged solar energy modules
    Polymer Degradation and Stability, 1997
    Co-Authors: Peter P Klemchuk, Myer Ezrin, Gary Lavigne, William Holley, James Galica, Susan Agro
    Abstract:

    Abstract The discoloration of EVA-based Encapsulant in some solar photovoltaic modules, most notably a mirror-enhanced module and others recovered from Carrisa Plains, CA, has been investigated in order to understand the causes of the phenomenon and to find solutions to the problem of reduced electrical output. The discoloration has been found to be due to interactions between cross-linking peroxide and some stabilizing additives, and is also likely to be due to oxidation of the Encapsulant. No evidence could be found in field-aged, discolored EVA Encapsulant for conjugated double bonds, which has been implicated as the cause of discoloration in earlier publications. Reformulated Encapsulant and the use of cerium-oxide-containing glass as the top cover of PV modules have dramatically reduced discoloration. Additional benefit should be derived by excluding oxygen from the modules.

Cheolsoo Sone - One of the best experts on this subject based on the ideXlab platform.

  • effects of the refractive index of the Encapsulant on the light extraction efficiency of light emitting diodes
    Optics Express, 2011
    Co-Authors: Frank W Mont, Fred E Schubert, Xing Yan, Jaehee Cho, Gi Bum Kim, Cheolsoo Sone
    Abstract:

    We investigate the effects of the refractive index of the Encapsulant on the light-extraction efficiency (LEE) of light-emitting diodes (LEDs) for GaN LEDs (n ≈ 2.5) and AlGaInP LEDs (n ≈ 3.0). For non-absorbing rectangular parallelepiped LED chips, as the refractive index of the Encapsulant increases, the LEE first increases quasi-linearly, then increases sub-linearly, and finally a saturation is reached. Furthermore, LEDs with a dual-layer graded-refractive-index (GRIN) Encapsulant (n(Encapsulant 1) = 1.57 and n(Encapsulant 2) = 1.41) is fabricated through a two-step curing process. We demonstrate that such an LED further enhances the LEE by reducing Fresnel reflection loss at the Encapsulant/air interface by 35% compared with an LED encapsulated with a single-layer Encapsulant (n(Encapsulant) = 1.57).

  • trapped whispering gallery optical modes in white light emitting diode lamps with remote phosphor
    Applied Physics Letters, 2006
    Co-Authors: Hong Luo, Fred E Schubert, Jaehee Cho, Cheolsoo Sone, Jong Kyu Kim, Yongjo Park
    Abstract:

    Three-dimensional ray tracing simulations show that a significant fraction of the phosphorescence emitted in high-power white light-emitting diode lamps with a remote phosphor is trapped as whispering-gallery modes propagating along the circumference of the Encapsulant. The whispering-gallery modes, which are a significant optical loss mechanism and occur for multiple shapes of the encapsulation dome, are shown to be sensitively dependent on the diffusivity of the reflector cup employed in the lamp. By employing a diffuse reflector cup, up to 86% of the trapped modes is extracted out from the Encapsulant. In addition, it is experimentally demonstrated that the phosphorescence efficiency is improved by up to 12.2% as the diffusivity of the reflector increases. The experimental results are consistent with theoretical ray tracing simulations.