Title:	Detecting and Understanding Sodium Movement in Solar Panel Encapsulant Polymers
Author(s):	S.L. Moffitt, B.H. Hamadani, X. Gu
Keywords:	Degradation, Encapsulation, PV Module, Interfaces
Topic:	Photovoltaic Modules and BoS Components
Subtopic:	PV Module Design, Manufacture, Performance and Reliability
Event:	37th European Photovoltaic Solar Energy Conference and Exhibition
Session:	4BO.12.4
Pages:	796 - 798
ISBN:	3-936338-73-6
Paper DOI:	10.4229/EUPVSEC20202020-4BO.12.4
Price:	0,00 EUR
Document(s):	paper

Abstract/Summary:

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Photovoltaic (PV) panels in large arrays operate at high voltages and, as a result, can experience potentialinduced degradation (PID). At these high voltages, leakage currents drive sodium out of the glass at the front of the panels, through the polymer encapsulant, and into the sensitive electronics at the core. Initial work by other groups has suggested that changing the polymeric encapsulant layer could limit sodium migration. However, the polymer characteristics and mechanisms that moderate sodium migration are not yet understood. In this work the role of panel encapsulants in PV panel PID is being investigated. Glass/encapsulant coupons will be exposed to high voltages to evaluate degradation. Several coupons contain PV cells that will be periodically monitored via current versus voltage measurements and electroluminescence imaging to track performance degradation. Coupon samples without cells will be cut to expose cross sections for materials characterization. Crosssectional analysis, using energy dispersive spectroscopy, will quantify the amount of sodium that has moved through different encapsulant polymers (ethylene-vinyl acetate, polyolefin, and ionomer). In tandem, the chemistry and structure of the polymers will be characterized to develop an understanding of which polymer characteristics limit sodium movement. An understanding of how polymer encapsulants can limit sodium migration will inform the development of next generation polymers. Improved polymer encapsulants that limit sodium migration will significantly increase the service lifetime of PV panels.