Keeping PV solar panels clean is vital to maintaining optimal efficiency. This is crucial with all PV devices, but keeping large scale solar farms in hot and often dusty countries can be an especially mammoth task. Self-cleaning solar panels help to keep the surfaces of PV panels cleaner for longer, keeping them working at maximum efficiency.
In hot, dusty conditions, a solar cell can lose up to 20% of its efficiency by being shaded by dust and dirt. But even here in the UK, dust, pollen and other airbourne particles can build up on our solar panels, just like they do on our cars if not regularly cleaned. During heatwaves, these can become “baked on” by the sun, making them harder to be washed away by the next rainfall.
Self-cleaning, hydrophobic coatings are designed to minimise the need for cleaning and maintaining the surface of solar panels. These coatings are sprayed onto the surface of the panel and prevent water from collecting or sticking to the surface. As water rolls off the surface of the panel, dust and other contaminants and picked up and washed away, keeping the panel cleaner for longer.
Which self-cleaning coatings are being developed?
A number of self-cleaning coatings for solar panels are currently in development, and are mostly intended for use on large-scale solar farms in hot, dry countries where dust is often a problem. One coating, designed to artificially replicate the surface of the lotus leaf, is currently being developed by Oak Ridge National Laboratory, Tennesee, USA. This coating is designed specifically for application to concave mirrors and heliostats used on solar farms. It is designed to provide up to a 90% reduction in mirror cleaning, whilst improving the level of sunlight reflected by 20%.
A similar technology is being developed by researchers at the University of Science and Technology (China) and Xi’an Technology University (China) and Cardiff University (UK). Together, they are working on the EU FP7 Laser NaMi project, in which micro-electric circuits are printed onto the surface of solar panels. These circuits are smaller than the wavelength of light, which in turn prevents light from being reflected from the surface of the panel and instead traps it, allowing more light to be harnessed for the generation of electricity. This technology also helps to make the surface of the solar panel hydrophobic and therefore self-cleaning. Water is unable to stick to the surface and particles of dirt are washed away more easily.
Domestic solar panels
While the world of self-cleaning solar panel technology is set to improve the efficiency of solar farms worldwide, there are also options on the market for hydrophobic coatings for domestic solar panels, though their effectiveness is still disputed. Self-cleaning solar panels are viable on a larger scale, on solar farms where individual cleaning would be time-consuming and expensive. Many argue that self-cleaning solar panels need to be mounted at a specific angle for their cleaning capabilities to function property and for water to flow away effectively, something which is harder to adapt to in a domestic environment. Nevertheless, some domestic solar panels are now marketed as “self cleaning” and coatings which can be bought and applied separately are also on the market.
Whether you own domestic self-cleaning solar panels or not, it is still important to give your panels regular attention in order to maximise their efficiency. For more information on keeping your solar panels clean, take a look at this article.
Image sourced: JollyrogertagscleaninghydrophobicPVsolar panels