MIT researchers develop waterless, contactless method to clean solar modules

Researchers at the Massachusetts Institute of Technology (MIT) have developed a method that uses static electricity to keep solar panels dust-free, eliminating the need to clean them with water.

Research has shown that dust can hamper the operation of solar panels by up to 30% in just one month without cleaning and a 3-4% reduction in solar panel power output would equate to a loss of 3.3 billion dollars and $5.5 billion in revenue.

The MIT team’s waterless, non-contact system uses electrostatic repulsion to effectively blast dust particles off the surface of the panel. To do this, an electrode in the form of a metal bar is passed over the surface of the panel, giving the dust particles an electric charge. A charge is then applied to the solar panel, which repels the dust particles, causing them to jump through the air and away from the panel.

The new system can run automatically on a timer using an electric motor and guide rails on the side of the panel that would run the electrode over the panel without directly touching the surface.

In practice, each solar panel could be equipped with guardrails on each side, with an electrode passing through the panel. Using a tiny portion of the panel’s output, a small electric motor could power the belt system to move the electrode from one end of the panel to the other to remove any dust particles. The whole process can be automated or controlled remotely. Alternatively, thin strips of conductive transparent material could be permanently disposed above the panel, eliminating the need for moving parts.

Experiments have proven that the process works effectively on a laboratory scale test setup using specially prepared laboratory dust samples with a range of particle sizes. Tests showed that the humidity in the air provided a thin layer of water on the particles, which was crucial for the effect to work. The researchers performed experiments at varying humidities from 5% to 95%. As long as the ambient humidity is above 30%, almost all particles on the surface can be removed. The process can become difficult as the humidity decreases.

Many of the largest solar energy installations in the world, including in China, India, the United Arab Emirates and the United States, are located in desert regions. The water used to clean these solar panels using pressurized water jets must be trucked in from a distance and must be very pure so as not to leave deposits on the surfaces. Dry scrubbing is sometimes used, but it is less effective at cleaning surfaces and can cause permanent scratches that reduce light transmission.

By eliminating water dependency and dust accumulation and reducing overall operating costs, these systems can significantly improve the overall efficiency and reliability of solar installations.

Water resources in India have always been a challenge. The Global Fund (WWF), in a report, said 30 Indian cities face imminent water-related risks unless immediate action is taken to mitigate and curb climate change.

Regarding the use of water in solar projects, the Ministry of New and Renewable Energy (MNRE) has issued a letter recommending the efficient use of water for cleaning modules in large-scale solar projects. The ministry said project developers were using too much water to clean solar modules and should try to minimize waste. The application of waterless robotic cleaning solutions is gaining acceptance in India.

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