By 2030, solar energy is projected to account for 10% of global electricity generation, largely sourced from sunny desert regions. However, dust accumulation on solar panels or mirrors poses a significant challenge—dust can decrease the efficiency of photovoltaic panels by up to 30% within just one month, making regular cleaning essential for such installations.
Currently, cleaning solar panels consumes approximately 10 billion gallons of water annually—enough to provide drinking water for up to 2 million people. Waterless methods, while less resource-intensive, are labor-intensive and often cause irreversible scratches on the surface, which can further reduce efficiency. Researchers at MIT have now developed a water-free, non-contact system that automates the cleaning of solar panels, addressing the dust issue effectively.
This innovative system employs electrostatic repulsion to separate dust particles from the panel's surface without the use of water or brushes. By passing a simple electrode over the solar panel, the system transfers charge to the dust particles, which are then repelled from the panel. This process can be automated using a motor and rails along the panel’s sides. MIT graduate student Sreedath Panat and mechanical engineering professor Kripa Varanasi detail their findings in the journal *Science Advances*.
Even though the world is advancing solar panel technology, ordinary issues like dust can significantly impact overall efficiency. Lab tests conducted by Panat and Varanasi revealed that energy output drops dramatically as dust accumulates, with reductions reaching 30% within a month if left uncleaned. For a 150 MW solar installation, even a 1% drop in power can result in an annual revenue loss of $200,000 (approximately RMB 1.27 million). Globally, a 3% to 4% reduction in power generation at solar farms could lead to losses ranging from $3.3 billion (RMB 20.9 billion) to $5.5 billion (RMB 34.9 billion), according to researchers.
“There is still much work to be done on solar materials,†said Varanasi. “Efforts are focused on improving efficiency by several percentage points.â€
Many of the world’s largest solar installations, including those in China, India, the UAE, and the U.S., are located in desert areas. The water used for cleaning these panels must be transported from afar and is required to be extremely pure to prevent residue on the surface. Dry wiping methods exist but are less effective and can cause permanent scratches, reducing light transmission.
Water cleaning constitutes roughly 10% of the operational costs of solar installations. Researchers suggest the new system could cut these expenses significantly.
“The water footprint in the solar industry is immense,†Varanasi noted, adding that it continues to grow as solar installations expand worldwide. “The industry must be mindful of sustainability.â€
Other groups have attempted electrostatic-based solutions, but these rely on electric screens featuring interdigital electrodes. According to Varanasi, these screens can malfunction due to moisture intrusion, making them impractical in Earth’s desert environments.
The MIT team’s solution requires only a single electrode—a simple metal rod passing over the panel—that generates an electric field to charge dust particles. By applying an opposite charge to a transparent conductive layer deposited on the glass cover of the solar panel, the researchers repelled the particles. Through precise voltage calculations, they determined levels strong enough to overcome gravity and adhesion, successfully removing the dust.
Experiments using specially prepared lab dust samples confirmed the system’s effectiveness. Tests showed that humidity in the air creates a thin layer of water on the particles, which is critical to the system’s success. “We experimented under humidity levels ranging from 5% to 95%,†Panat stated. “As long as the humidity exceeds 30%, we can remove nearly all particles, but lower humidity makes it more challenging.â€
“The good news is that most deserts actually fall into the 30%-plus humidity range,†Varanasi added. Even drier regions typically experience higher humidity in the early morning, leading to condensation, allowing for regular cleaning cycles.
Unlike earlier electric screen efforts, which falter under high humidity, Panat explained that their system operates effectively at up to 95% humidity.
On a larger scale, electrodes can be mounted on both sides of each solar panel. A small motor drives the electrodes across the panel’s length, shedding all dust. The entire process can be automated or remotely controlled. Alternatively, thin strips of conductive transparent material can be permanently installed above the panel, eliminating the need for moving parts.
Varanasi emphasized that by eliminating reliance on water transport and preventing corrosive compounds in dust buildup, the system reduces overall operational costs and enhances the efficiency and reliability of solar installations.
(Original content adapted from: Daily Solar News Network)
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