EU PVSEC Programme Online
EU PVSEC 2021, 6 - 10 September 2021
Presentation: 4CO.1.4 Degradation Evaluation of Thermoplastic Polyolefin Encapsulant Used in c-Si PV Modules and Laminates
Type: Oral
Date: Wednesday, 8th September 2021
08:30 - 10:00
Author(s): B. Adothu, F.R. Costa, S. Mallick
Presenter / Speaker: B. Adothu, IIT Bombay, Mumbai, India
Event: Conference Conference
Session: 4CO.1 Polymers and Encapsulation of PV Modules
Topic: 4. 1 PV Module Design, Manufacture, Performance and Reliability
Keywords: Encapsulant/s, Ethylene Vinyl Acetate (EVA), PV Module, Thermoplastic Polyolefin, Fluorescence
Summary / Abstract: Reliability and degradation product evaluation is the most important study to predict the long-term performance of new materials used in photovoltaic (PV) module encapsulation. Thermoplastic polyolefin (TPO) is a newly developed non-crosslinking encapsulant. Its reliability and degradation products have been evaluated and compared with the most commonly used ethylene vinyl acetate (EVA) copolymer under UV and damp heat aging conditions. EVA glass-to-glass laminate shows strong fluorescence at the center, whereas TPO did not show any fluorescence during UV-365 aging. It has been found that the fluorescence brim pattern dominated in between the edge and center of solar cell for EVA, whereas TPO dominated only at the edges. This is due to the EVA mini PV laminate has four times higher oxygen diffusion length and coefficient than the TPO PV laminates during the Xenon aging. UV dose of 367.2 and 162 kWh/m2 is sufficient to detect the early-stage UV-induced discoloration degradation under the hot-dry climatic aging conditions. Electroluminescence images of TPO shows insignificant changes, whereas EVA shows strong metallization corrosion in 4000 h damp-heat tested PV modules. Due to this, overall 5% and & 7% power degradation has been observed for TPO and EVA, respectively. A factor of nine times higher acid index difference and two times higher hydroxyl index have been identified with infrared spectroscopy for EVA as compared to the TPO. A higher yellowness index has been observed for EVA during all three aging conditions. This work will help the PV industry and encapsulant manufacturers to understand the TPO degradation behavior in hot-dry and hot-humid situations.