Affordable Access

Publisher Website

UV LED ageing of polymers for PV cell encapsulation

Authors
  • Pinochet, Nicolas
  • Pirot-Berson, Lucie
  • Couderc, Romain
  • Therias, Sandrine
Publication Date
Aug 14, 2024
Identifiers
DOI: 10.1038/s41529-024-00501-6
OAI: oai:HAL:hal-04740438v1
Source
HAL-CEA
Keywords
Language
English
License
Unknown
External links

Abstract

Encapsulation polymers in terrestrial solar modules degrade due to ultraviolet radiation from the sun. To assess a polymer's durability under UV light, accelerated aging tests can be conducted. A new LEDs device allows us to investigate the effects of temperature, irradiation, and UV source spectrum on the photooxidation mechanism and kinetics of two polyethylene-based commercial encapsulants, differentiated by the presence or absence of UV absorbers. The photooxidation rate of the polymer matrix increases as the temperature and irradiance increase between 62 and 82 °C, and 12 and 28 W.m -2 , respectively. In the last case, the photooxidation rate is not proportional to the number of photons. Finally, we observed different distributions of degradation products under UVB radiation at 305 nm compared to those under UVA radiation at 365 nm. UVB photons enable Norrish reactions that are not possible with UVA alone. Special care is needed to maintain a balance between UVA and UVB photons to ensure representative durability tests. With a few adjustments to its emission spectrum, UV LED devices appear to be good candidates for accelerated aging of encapsulation polymers.</p></div> <div>Photovoltaic (PV)silicon-basedcells have been used<p>Q1 Q1 as a clean energy source since the 1970s. To date, their efficiency has been improving continuously thanks to advances in architecture, materials, and processing 1 . To preserve their high performance against environmental stresses such as mechanical load, corrosive chemicals, temperature, and high-energy light, they rely on the PV module structure to minimize the induced degradation mechanisms. PV modules are generally made of front and back protection layers that surround two polymer sheets that encapsulate PV cells. The front layer is usually made of glass, and the back layer can be glass or a multilayer polymer (backsheet). The polymer sheets inside the module are called encapsulants. They are key players in light transmission, electrical insulation, mechanical stress absorption, heat removal, chemical barrier protection and PV module integrity. To maintain such properties throughout a module lifetime that is now ~30 years 2 , encapsulants must cope with the most stringent terrestrial conditions that lead to highly detrimental chemical reactions such as hydrolysis or photooxidation. Concerning terrestrial applications, most photodegradation reactions of encapsulants involve UV light between 300 and 400 nm 3 . Consequently, accelerated photoaging tests are usually run under various UV sources, including xenon arcs or fluorescent tubes, which simulate this part of the solar spectrum 4 .

Report this publication

Statistics

Seen <100 times