Deposition of a transparent, electrically sensitive material
on glass or a transparent plastic film eliminates about 90 percent of dust,
dramatically boosting efficiency of solar panels.
In a report at the National Meeting of the American Chemical Society (ACS), scientists describe how a self-cleaning coating on the surface of solar cells could increase the efficiency of producing electricity from sunlight and reduce maintenance costs.
Sensors monitor dust levels on the surface of the panel and energize the material when dust concentration reaches a critical level. The electric charge sends energy over the surface of the material, moving dust off of the panel's edges.
"We think our self-cleaning panels used in areas of high dust and particulate pollutant concentrations will highly benefit the systems' solar energy output," says study leader Malay K. Mazumder. "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."
Electrodynamic screens (EDS) are composed a series of parallel electrodes on a substrate that is energized by a three-phase high-voltage amplifier. One potential weakness is the requirement of an external power source, but that can be overcome if the EDS can derive power from the solar panel.
Use of solar, or photovoltaic, panels increased by 50 percent from 2003 to 2008, and forecasters predict 25 percent annually. Large-scale solar installations already exist in the U.S., Spain, Germany, the Middle East, Australia and India.
As a general rule, they are located in dry areas where winds sweep dust into the air and deposit it onto the surface of solar panels. The dust reduces the amount of light that can enter the business part of the solar panel, decreasing the amount of electricity produced. Cleaning the panels is difficult because of scarcity of water.
"A dust layer of one-seventh of an ounce per square yard decreases solar power conversion by 40 percent," Mazumder says. "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."
Mazumder initially developed the self-cleaning solar panel technology for use in NASA's lunar and Mars missions. "Mars of course is a dusty and dry environment," Mazumder says, "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 current market size for solar panels is about $24 billion, according to Mazumder. "Less than 0.04 percent of global energy production is derived from solar panels, but if only four percent of the world's deserts were dedicated to solar power harvesting, our energy needs could be completely met worldwide. This self-cleaning technology can play an important role."
Mazumder was part of a team at the Dept. of Applied Science, Dept. of Systems Engineering at the University of Arkansas at Little Rock that worked on the project. They were awarded a patent for their work in 2005.