The accumulation of dust on solar panels or mirrors is already a significant issue – it can reduce the output of photovoltaic panels. So regular cleaning is essential for such installations to maintain their peak efficiency. However, cleaning solar panels is currently estimated to use billions of gallons of water per year, and attempts at waterless cleaning are labor-intensive and tend to cause irreversible scratching of the surfaces, which also reduces efficiency. Robots can be useful; recently, a Belgian startup developed HELIOS, an automated cleaning service for solar panels.
Now, a team of researchers at MIT has now developed a waterless cleaning method to remove dust on solar installations in water-limited regions, improving overall efficiency.
The waterless, no-contact system uses electrostatic repulsion to cause dust particles to detach without the need for water or brushes. To activate the system, a simple electrode passes just above the solar panel‘s surface. The electrical charge it releases repels dust particles from the panels. The system can be operated automatically using a simple electric motor and guide rails along the side of the panel.
The team designed and fabricated an electrostatic dust removal system for a lab-scale solar panel. The glass plate on top of the solar panel was coated with a 5-nm-thick transparent and conductive layer of aluminum-doped zinc oxide (AZO) using atomic layer deposition (ALD) and formed the bottom electrode. The top electrode is mobile to avoid shading and moves along the panel during cleaning with a linear guide stepper motor mechanism. The system can be operated at a voltage of around 12V and can recover 95% of the lost power after cleaning for particle sizes greater than around 30 μm.
“We performed experiments at varying humidities from 5% to 95%,” says MIT graduate student Sreedath Panat. “As long as the ambient humidity is greater than 30%, you can remove almost all of the particles from the surface, but as humidity decreases, it becomes harder.”
By eliminating the dependency on trucked-in water, by eliminating the build-up of dust that can contain corrosive compounds, and by lowering the overall operational costs, such cleaning systems have the potential to significantly improve the overall efficiency and reliability of solar installations Kripa Varanasi says.