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
. "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
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.