“…Finally, two small bands occur at 1020 and 720 cm −1 , which is attributed to C-O bond stretching and methylene (-CH 2 ) rocking vibration, respectively. The bands that are present in the sample U-EVA indicate the presence of the functional groups present in EVA’s known structure and are in agreement with the work of Dias and Geretschläger 32,33 .Figure 1The FT-IR spectra of the EVA and backsheet samples as U-EVA, V-EVA, UB-dull, UB-shiny, UB-milled, white residue, VB and VB-milled samples.…”
Section: Resultssupporting
confidence: 84%
“…This is not exclusive, however, as in recent years there have been advancements in PV backsheet construction to attempt to replace Tedlar®, which holds the highest market share of PV backsheet materials of approximately 80% 30 . Some of the alternatives that are being used are Polyesters, e-layers of ethylene copolymers, polyamides or blends with poly(methyl methacrylate) (PMMA) 31,32 . However, Tedlar® will still represent the largest share of the disposal issue; at least initially until the market shares align with a new industry standard.…”
Global exponential increase in levels of Photovoltaic (PV) module waste is an increasing concern. The purpose of this study is to investigate if there is energy value in the polymers contained within first-generation crystalline silicon (c-Si) PV modules to help contribute positively to recycling rates and the circular economy. One such thermochemical conversion method that appeals to this application is pyrolysis. As c-Si PV modules are made up of glass, metal, semiconductor and polymer layers; pyrolysis has potential not to promote chemical oxidation of any of these layers to help aid delamination and subsequently, recovery. Herein, we analysed both used polymers taken from a deconstructed used PV module and virgin-grade polymers prior to manufacture to determine if any properties or thermal behaviours had changed. The calorific values of the used and virgin-grade Ethylene vinyl acetate (EVA) encapsulant were found to be high, unchanged and comparable to that of biodiesel at 39.51 and 39.87 MJ.Kg
−1
, respectively. This result signifies that there is energy value within used modules. As such, this study has assessed the pyrolysis behaviour of PV cells and has indicated the energy recovery potential within the used polymers found in c-Si PV modules.
“…Finally, two small bands occur at 1020 and 720 cm −1 , which is attributed to C-O bond stretching and methylene (-CH 2 ) rocking vibration, respectively. The bands that are present in the sample U-EVA indicate the presence of the functional groups present in EVA’s known structure and are in agreement with the work of Dias and Geretschläger 32,33 .Figure 1The FT-IR spectra of the EVA and backsheet samples as U-EVA, V-EVA, UB-dull, UB-shiny, UB-milled, white residue, VB and VB-milled samples.…”
Section: Resultssupporting
confidence: 84%
“…This is not exclusive, however, as in recent years there have been advancements in PV backsheet construction to attempt to replace Tedlar®, which holds the highest market share of PV backsheet materials of approximately 80% 30 . Some of the alternatives that are being used are Polyesters, e-layers of ethylene copolymers, polyamides or blends with poly(methyl methacrylate) (PMMA) 31,32 . However, Tedlar® will still represent the largest share of the disposal issue; at least initially until the market shares align with a new industry standard.…”
Global exponential increase in levels of Photovoltaic (PV) module waste is an increasing concern. The purpose of this study is to investigate if there is energy value in the polymers contained within first-generation crystalline silicon (c-Si) PV modules to help contribute positively to recycling rates and the circular economy. One such thermochemical conversion method that appeals to this application is pyrolysis. As c-Si PV modules are made up of glass, metal, semiconductor and polymer layers; pyrolysis has potential not to promote chemical oxidation of any of these layers to help aid delamination and subsequently, recovery. Herein, we analysed both used polymers taken from a deconstructed used PV module and virgin-grade polymers prior to manufacture to determine if any properties or thermal behaviours had changed. The calorific values of the used and virgin-grade Ethylene vinyl acetate (EVA) encapsulant were found to be high, unchanged and comparable to that of biodiesel at 39.51 and 39.87 MJ.Kg
−1
, respectively. This result signifies that there is energy value within used modules. As such, this study has assessed the pyrolysis behaviour of PV cells and has indicated the energy recovery potential within the used polymers found in c-Si PV modules.
“…While E varies across different foils, the moduli of several photovoltaic module BS foils containing PET as the core layer have been reported to range from around 2000 to 3100 MPa (at room temperature). 22 By contrast, our experimental results show a considerably higher modulus for the particular foil studied, with values ranging between around 5000 (at room temperature) and 4000 MPa in both MD and TD. Nevertheless, it is also important to mention that the PET-based BS foil used in this study was coated with two thin layers, which have an influence on their elastic behavior, therefore, their E values.…”
The characterization of mechanical properties of polymeric backsheet and encapsulation foils of photovoltaic (PV) modules usually involves destructive techniques, such as dynamic mechanical analysis and tensile testing. In this article, we validate the scanning acoustic microscopy (SAM) as a nondestructive characterization method to estimate the mechanical properties of polymeric multi‐layers in PV modules. The acoustic speed inside each individual material is measured and its mechanical properties calculated. For this validation, other techniques are employed to determine the values of density, thickness, and elastic modulus of the foils. The viscoelastic properties of the polymeric foils are temperature dependent. The longitudinal modulus measured acoustically at 15 MHz and the Young's modulus from conventional tensile testing were compared at different temperatures. Both techniques show good agreement regarding the change in mechanical properties caused by temperature variation. The disagreement in the absolute values of these parameters is explained by the different frequency magnitudes at which both measurements are performed. This confirms that SAM is a reliable technique to measure changes in the viscoelastic properties of the foils in PV modules nondestructively, and thus to obtain more information about aging‐induced material changes and degradation.
“…Degradation of the backsheet including blistering and cracking (Figure A) is commonly observed in field and after accelerated testing and can compromise module reliability . Mechanical characterization of backsheets has mostly involved delamination and tensile testing; however, there remains a significant lack of understanding in the cracking or tearing properties in spite of their importance to the reliability of PV modules.…”
The backsheet in photovoltaic modules belongs to an important class of layered materials where the tearing behavior of the individual layers does not necessarily represent the tearing behavior of the entire backsheet. Such characteristic arises from the interaction between the individual layers during the tearing process, where one layer of the backsheet is mechanically constrained by its neighboring layers and the layers may debond from each other. The mechanical constraint and debonding change the amount of energy dissipated during tearing and affect the overall tearing energy. In this work, we exposed a wide selection of backsheets with polymers including ethylene‐vinyl acetate (EVA), polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), and ethylene tetrafluoroethylene (ETFE) to damp heat (85°C/85%RH) for up to 2000 hours. We report on the effect of damp heat on the tearing energy as a function of damp heat exposure. We developed a model that describes the tearing energy of a layered structure by accounting for the tearing of the individual layers in the backsheet, the effect of mechanical constraint, and the adhesive debonding between the layers. Additionally, we explore the relationship between the microstructural change in the polymers which resulted from the damp heat exposure and the mechanical properties using modulated differential scanning calorimetry (MDSC), small and wide angle X‐ray scattering (SAXS and WAXS), and tensile testing.
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