DO YOUR parents find dusting the house a chore, or dread washing the windows? Imagine keeping dust and grime off objects spread out over an area of 25-50 football fields.
That’s the problem facing companies that deploy large-scale solar-power installations.
However, American scientists have come up with a solution, at least for photovoltaics – self-dusting solar panels based on technology developed for space missions to Mars.
They say that a self-cleaning coating on the surface of solar cells could increase the efficiency of producing electricity from sunlight and reduce maintenance costs for large-scale solar installations.
“We think our self-cleaning panels used in areas of high-dust and particulate-pollutant concentrations will highly benefit the systems’ solar energy output,” study leader Malay K. Mazumder, of Boston University, says.
“Our technology can be used in both small and large-scale photovoltaic systems. To our knowledge, this is the only technology for automatic dust cleaning that doesn’t require water or mechanical movement.”
Mazumder says the need for such a solution is growing with the popularity of solar energy. Use of solar panels has increased dramatically in recent years, including in northern Europe.
Large-scale solar installations already exist in the US, Spain, Germany, the Middle East, Australia and India. These are usually located in sun-drenched desert areas where dry weather and winds sweep dust into the air and deposit it on to the surface of the solar panels.
Just like grime on a household window, that dust reduces the amount of light that can enter the business part of the solar panel, decreasing the amount of electricity produced. Clean water tends to be scarce in these areas, making it expensive to clean the solar panels.
“A dust layer of one-seventh of an ounce (four grams) per square yard (0.84sq m) decreases solar power conversion by 40%,” says Mazumder. “In Arizona, dust is deposited each month at about four times that amount. Deposition rates are even higher in the Middle East, Australia and India.”
Working with Nasa, Mazumder and colleagues initially developed the self-cleaning solar-panel technology for use in lunar and Mars missions.
“Mars, of course, is a dusty and dry environment, and solar panels powering rovers and future manned and robotic missions must not succumb to dust deposition. But neither should the solar panels here on Earth.”
The self-cleaning technology involves deposition of a transparent, electrically sensitive material deposited on glass or a transparent plastic sheet covering the panels.
Sensors monitor dust levels on the surface of the panel and energise the material when dust concentration reaches a critical level.
The electric charge sends a dust-repelling wave cascading over the surface of the material, lifting away the dust and transporting it off of the screen’s edges.
Mazumder says, that within two minutes, the process removes about 90% of the dust deposited on a solar panel and requires only a small amount of the electricity generated by the panel for cleaning operations.