The principle of self-cleaning was discovered in 1973 by the botanist Wilhelm Barthlott and his team at the University of Bonn. As the name suggests, “self-cleaning technology” can remove dirt from the surface of the material and requires a minimal amount of maintenance, which also allows to significantly reduce the cleaning costs. The development of such materials is due to the advancement in the field of nanotechnology, where the thin film coating technology impacts the self-cleaning property to the glass.

 

In the technological applications, the cleaning process without the need for any manpower, moving mechanism or robot is also included in the scope of "self cleaning technology". For example, thanks to this technology, the surface of solar panels can remain clean by removing pollution and/or actively cleaning themselves when necessary, regardless of time of day, sunlight intensity, sunlight location, or rainy conditions. Hereby, it can continue to work while maintaining production efficiency. It can classified as “passive” and “active” for developing self-cleaning technologies solutions for solar panel cleaning.

 

Active self-cleaning solutions; they are not based on the principle of film coatings, they are controllable. The two most well-known types are electrostatic and ultrasonic self-cleaning methods.

Passive self-cleaning solutions; they include several different types of surface coatings. This method is based on surface energy modification or photo-chemical reactions. Three main types of coatings can be used for this purpose:

  • Hydrophobic/Superhydrophobic (Low Surface Energy Coatings) – Lotus Effect (lotus leaf effect): These are low surface energy coatings that remove all contaminants from the surface such as dust. Self-cleaning surface technology is often associated with the “lotus leaf effect”, where water has a high contact angle, easily rolls along the surface as a drop when it drips onto the surface, and collects all the contaminants on itself.
  • Hydrophilic/Superhydrophilic (High Surface Energy Coatings): These are coatings with high surface energy that work by spreading water over the surface. As a result, water flows freely on the surface and removes all contaminants.
  • Photocatalytic (chemical decomposition using UV light and water): When exposed to an ultraviolet (UV) light source such as the sun, the oxidative property of the coating decomposes and breaks down the organic materials deposited on the coating's surface. Thus, the protection of the clean surface is ensured.