2020_Degradation of Hydrophobic, Anti-Soiling Coatings_Energies.pdf (6.11 MB)

Degradation of hydrophobic, anti-soiling coatings for solar module cover glass

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journal contribution
posted on 30.07.2020, 09:06 by Fabiana Lisco, Farwah Bukhari, Sona Ulicna, Kenan Isbilir, Kurt L Barth, Alan Taylor, Michael Walls
Soiling of solar module cover glass is a serious problem for solar asset managers. It causes a reduction in power output due to attenuation of the incident light, and reduces the return on investment. Regular cleaning is required to mitigate the effect but this is a costly procedure. The application of transparent hydrophobic, anti-soiling coatings to the cover glass is a promising solution. These coatings have low surface energy and contaminants do not adhere well. Even if soiling does remain on the coated surface, it is much more easily removed during cleaning. The performance of the coatings is determined using the water contact angle and roll-off angle measurements. However, although hydrophobic coatings hold out great promise, outdoor testing revealed degradation that occurs surprisingly quickly. In this study, we report on results using laboratory-based damp heat and UV exposure environmental tests. We used SEM surface imaging and XPS surface chemical analysis to study the mechanisms that lead to coating degradation. Loss of surface fluorine from the coatings was observed and this appeared to be a major issue. Loss of nanoparticles was also observed. Blistering of surfaces also occurs, leading to loss of coating material. This was probably due to the movement of retained solvents and was caused by insufficient curing. This mechanism is avoidable if care is taken for providing and carrying out carefully specified curing conditions. All these symptoms correlate well with observations taken from parallel outdoor testing. Identification of the mechanisms involved will inform the development of more durable anti-soiling, hydrophobic coatings for solar application.

Funding

SOLplus - Improved Energy Efficiency of Solar PV Systems via Low Surface Energy Coatings : EP/N510014/1

Active Building Centre: LU Research Cluster Budget (EPSRC) : EP/S016627/1

Innovate UK for the ‘Always Clean’ project

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Research Unit

  • Centre for Renewable Energy Systems Technology (CREST)

Published in

Energies

Volume

13

Issue

15

Publisher

MDPI AG

Version

VoR (Version of Record)

Rights holder

© The Authors

Publisher statement

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Acceptance date

21/07/2020

Publication date

2020-07-24

Copyright date

2020

eISSN

1996-1073

Language

en

Depositor

Prof Michael Walls. Deposit date: 30 July 2020

Article number

3811

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