Electrically-induced degradation of polyester films for photovoltaic devices

  • Rong Tang

Student thesis: Doctoral Thesis

Abstract

Poly(ethylene terephthalate) (PET) is one of the most common thermoplastics that has been widely used in nearly every field all over the world. Particularly, PET is utilized as a core layer in the backsheets of photovoltaic panels to provide electrical insulation and mechanical stability.Partial discharge (PD) is localized dielectric breakdown that usually occurs in voids or air gaps within solid or liquid insulation systems. Long-term PD exposure can significantly deteriorate the system and cause final breakdown. PD is believed to be able to occur in PV backsheets under certain circumstances and this is obviously a potential risk of safe operation for the PV modules. PET, as usually being the thickest layer of the backsheet with excellent insulation properties, greatly determines the PD behaviour of the PV backsheet. Therefore a comprehensive understanding of PD-induced degradation and dielectric breakdown of PET films will be vital.In this project, various types of PET films were studied to understand how physical and chemical properties influence the PD-induced degradation and breakdown of the PET films. Efforts have endeavoured to focus on three primary aspects: morphology effect, performance additive effect and weathering effect.The main contributions of this work are: the morphology effect has been quantitatively analysed and a straightforward method was introduced to significantly improve the sample performance; great enhancement in voltage endurance has been found once the PET sample equipped with a phosphorus-based flame retardant; the weathering effect (UV and hydrolysis) on the PD-induced degradation and breakdown of PET was investigated for the first time ever.
Date of Award1 Oct 2014
LanguageEnglish
Awarding Institution
  • University Of Strathclyde
SupervisorJohn Liggat (Supervisor) & Wah Hoon Siew (Supervisor)

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