Dust on solar panels reduces their output significantly, so they need to be kept clean. But what’s the best way to do that? Scientists at the Massachusetts Institute of Technology (MIT) say they have a solution.
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One of the most common ways to clean dust off solar panels is to spray them with water. But that’s a huge waste of water, especially in desert settings, where there are a lot of solar farms. The MIT scientists note in their new study, which is published in Science Advances:
At a global PV capacity above 500 GW, we estimate on the basis of reports that up to 10 billion gallons of water are being consumed every year worldwide for solar panel cleaning purposes, which can otherwise satisfy the annual water needs of up to two million people in developing and underdeveloped countries.
Further, dry scrubbing damages solar panels.
According to the researchers, static electricity can keep dust off solar panels, and is a much more sustainable solution. And that’s important, because as the researchers note, for example, “Dust accumulation of 5 mg/cm2 corresponds to almost 50% loss in power output.”
The researchers achieved this by using “adsorbed moisture-assisted charge induction.” Adsorption is when moisture in the air attaches to a dust particle’s surface. Cosmos concisely explains how it works:
The new technique works by passing a simple electrode – a conductor of electricity, which could be a simple metal bar – just above the surface of the solar panel. The electric field produced by the electrode causes the dust particles to become electrically charged as well.
The same charge the dust holds is then applied to the solar panel’s surface through a conductive layer a few nanometers thick. The researchers have calculated the voltage range to apply to overcome the pull of gravity and adhesion forces, so the dust particles are pushed from the surface until they fall off.
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In real-world scale and practice, the authors suggest that every solar panel could be fitted with railings on each side, with an electrode spanning across the panel. A small electric motor, perhaps even using electricity output from the panel itself, could then drive a belt system to move the electrode back and forth.
This method works in environments where the ambient humidity is at 30% or greater, and most deserts can achieve humidity of around 30%.
What do you think about this proposed solar panel cleaning method? Let us know in the comments below.
Read more: These light, thin, flexible solar panels ‘peel and stick’ to roofs
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