A Novel Low Reflection, Anti-Soiling, Polymer/Glass Laminate for Solar Module Cover Glass

• Main Authors: Jones, Luke O., Law, Adam M., Haydock-Wilson, Alex, Greenhalgh, Rachael C., Walls, John M.
• Format: Conference Proceeding
• Language: English
• Subjects: Adhesives; anti-soiling; Coatings; durability testing; Glass; hydrophobic; Laminates; low reflection; Photovoltaics; polymer laminate; Polymers; porous; Reflection; Refractive index; Solar panels; Surface cleaning; Warranties
• ISSN: 2995-1755
• DOI: 10.1109/PVSC57443.2024.10749140

Reflections and soiling of module cover glass attenuate the light entering a solar module, reducing power output. Here we introduce a new concept that reduces reflection and provides effective anti-soiling using a low energy, hydrophobic surface. The concept retains the cover glass with its structural strength and water impermeability. The cover glass is laminated with a relatively thin polymer sheet, typically 50um thick. The polymer has a low refractive index below that of glass (\mathrm{n} < 1.5) for low reflection, increasing the transmission of light into the module by up to 3%. It is also hydrophobic to reduce adhesion to soiling. The polymer must be chemically inert and environmentally stable, with excellent humidity and UV resistance. In dry climates, the reduced adhesion of the soiling makes the surface easier to clean. In wet climates, the water droplets cohere and roll off to create a 'self-cleaning' effect. A number of candidate polymers exist, and Ethylene Tetrafluoroethylene (ETFE) is a material already in use in the photovoltaic industry for use in lightweight modules. It has a refractive index of \mathrm{n}=1.4 and is highly hydrophobic with a water contact angle (WCA) of > 130^{\circ} . An ETFE/glass laminate has been fabricated and its properties and performance measured. The advantages over conventional single layer porous \text{SiO}_{2} coatings are discussed.