Ordinarily, water is used to clean off the layer of dust that continuously accumulates on solar panels. In arid regions, however, doing so can be challenging. A new system addresses this problem, by substituting electrostatic repulsion for water.
Deserts are popular locations for solar farms, given that they're very sunny and contain a lot of wide-open spaces. Unfortunately, they're also quite dusty, meaning that solar panels quickly get covered with a layer of dust which impedes their performance.
As a result, the coating of dust frequently has to be rinsed off with fresh water. In many cases, that water has to be trucked in from far away, consuming a lot of time and energy. What's more, if the water wasn't being utilized to clean the panels, it could instead be used for drinking or irrigation.
One alternative is to brush the dust off without using any water. This might be OK to do every once in a while, but over time it scratches up the surface of the panels, reducing their efficiency just like the dust. With such limitations in mind, a team from MIT created the new no-water, contact-free cleaning system.
It incorporates an electrode that could take the form of a panel-width motor-driven metal bar, along with an ultra-thin transparent film containing aluminum doped with zinc oxide – the film is applied to the sun-facing surface of a regular solar panel.
When the panel needs to be cleaned, an electrical charge is applied to the bar, which passes closely over the surface of the panel on a set of rails. As it does so, it produces an electrical field that charges the dust particles. An opposite electrical charge is then applied to the film, repelling the particles that are on it, causing them to jump off.
The system could operate without human supervision, powered by the solar farm itself. It should be noted that the setup does require an ambient humidity of at least 30 percent, which the scientists state most deserts actually meet throughout most of the day. Even in cases where the air is generally drier, it would likely still meet the minimum humidity requirement early in the morning, after dew has formed on the panel.
In fact, unlike previously developed electrostatic-repulsion-based systems, which don't work in overly humid conditions, the MIT system is able to function at an ambient humidity of up to 95 percent.
A paper on the research – which is being led by graduate student Sreedath Panat and Prof. Kripa Varanasi – was recently published in the journal Science Advances. The proof-of-concept model can be seen in action, in the video below.
Source: MIT
