Solar panel efficiency has increased dramatically in recent years as the technology advances. But a much more mundane problem persists: solar panels cannot effectively absorb sunlight when dirty. Compounding the problem, large arrays are often installed in hot, dry locations, which require high volumes of clean water to get rid of dust.
Scientists at the Massachusetts Institute of Technology have developed an alternative solution that involves no water at all.
In March 2022, Sreedath Panat, a graduate student at MIT, and Kripa Varanasi, professor of mechanical engineering, announced that they have devised a way to automatically clean solar panels, or the mirrors of solar thermal plants, in a waterless, no-contact system.
The system uses electrostatic repulsion to cause dust particles to detach and virtually leap off the panel’s surface, without the need for water or brushes.
The implementation is relatively simple. It requires an electrode, which can be a simple metal bar, to pass over the panel. This produces an electric field that imparts a charge to the dust particles as it goes. An opposite charge applied to a transparent conductive layer just a few nanometers thick deposited on the glass covering of the panel then repels the particles. Through experimentation involving different-sized dust particles, the researchers found a voltage range sufficient to overcome the pull of gravity and adhesion forces and cause the dust to lift away.
The scientists noted that many of the largest solar power installations in the world are located in desert regions. Also, water cleaning makes up about 10% of solar installation operating costs. Solar panels that aren’t cleaned after just one month can have up to a 30% reduction in output.
The electrostatic repulsion system could address these issues. By eliminating the need to ship in pure water to remote locations, solar panels would be more sustainable, operation costs would be reduced and the efficiency and reliability of panels would increase.