Can Photovoltaic Modules Clean Themselves Automatically?

Self-cleaning photovoltatic (PV) modules utilize both passive and active mechanisms for repelling debris and dust from the module surface. The following describes what these mechanisms for self-cleaning PV modules are:
Passive Methods: Nature-inspired cleaning. Applications of the lotus effect, coatings have recently come to market and provide a self-cleaning ability to remove dirt through water-repellent properties. According to studies, it can reduce dirt build-up on surfaces by 12 to 24 percent. Photocatalytic Coatings (PC) are another example of how coating technology has advanced through the addition of titanium dioxide. PC coatings work with the help of sunlight to store and convert organic matter, such as bird droppings, on solar panels. 
Active Methods: Technology-driven cleaning. Electrostatic repulsion is a method of using thin electrodes placed across the surface of a PV module to create an electric field that repels dust and debris. In a test of this method in arid desert locations, the electric field reduced the amount of dust and debris deposited on PV modules by more than 40 percent, while eliminating the need for water, which is normally required for cleaning. An additional example of a robotic scrubber is the Ecoppia E4, which utilizes automated brushes to remove debris from photovoltaic modules to increase the cleaning efficiency of photovoltaics by 25%.

When using robotic cleaning systems at Tokyo Skytree (for the 1,000+ solar panels), eight percent (8%) of lost electric energy from panel cleaning has been removed (from fifteen percent (15%) loss to three percent (3%) loss) and operations use less than ten percent (10%) of the water that would normally be used for manual cleaning processes.

In Australia's Outback, electrostatic dust screens​ keep panels operational. These systems, powered by solar energy, reduced maintenance costs by 60%.

Cost Savings: The self-cleaning coating reduces both water use by approximately 70% and labour costs by 50%.

Increased Efficiency: The farm is able to achieve 95% or greater of peak output throughout the entire year due to the self-cleaning coating.

Durability: This coating has two benefits: Firstly, it provides protection from micro-scratch damage caused by heavy or airborne particulates (such as dirt), thus prolonging the life of solar panels (greater than ten years when coated).

Self-cleaning tech has potential, but there are issues:

The initial cost is high. Robotic systems can be $500–1,000 per panel.
Electrostatic systems don't work well in humid places where dust sticks.
Textured coatings can change how a building looks.

Solar-Powered Waterless Systems: Combining UV light and nano-abrasives for "scrub-free" cleaning.