New Efficiency Records

New World Record Achieved in Solar Cell Technology
New Solar Cell Breaks the "40 Percent Efficient" Sunlight-to-
Electricity Barrier

U.S. Department of Energy (DOE) Assistant Secretary for Energy
Efficiency and Renewable Energy Alexander Karsner today announced
that with DOE funding, a concentrator solar cell produced by Boeing-
Spectrolab has recently achieved a world-record conversion efficiency
of 40.7 percent, establishing a new milestone in sunlight-to-
electricity performance. This breakthrough may lead to systems with
an installation cost of only $3 per watt, producing electricity at a
cost of 8-10 cents per kilowatt/hour, making solar electricity a more
cost-competitive and integral part of our nation's energy mix.

"Reaching this milestone heralds a great achievement for the
Department of Energy and for solar energy engineering worldwide,"
Assistant Secretary Karsner said. "We are eager to see this
accomplishment translate into the marketplace as soon as possible,
which has the potential to help reduce our nation's reliance on
imported oil and increase our energy security."

Attaining a 40 percent efficient concentrating solar cell means
having another technology pathway for producing cost-effective solar
electricity. Almost all of today's solar cell modules do not
concentrate sunlight but use only what the sun produces naturally,
what researchers call "one sun insolation," which achieves an
efficiency of 12 to 18 percent. However, by using an optical
concentrator, sunlight intensity can be increased, squeezing more
electricity out of a single solar cell.

The 40.7 percent cell was developed using a unique structure called a
multi-junction solar cell. This type of cell achieves a higher
efficiency by capturing more of the solar spectrum. In a multi-
junction cell, individual cells are made of layers, where each layer
captures part of the sunlight passing through the cell. This allows
the cell to get more energy from the sun's light.

For the past two decades researchers have tried to break the "40
percent efficient" barrier on solar cell devices. In the early 1980s,
DOE began researching what are known as "multi-junction gallium
arsenide-based solar cell devices," multi-layered solar cells which
converted about 16 percent of the sun's available energy into
electricity. In 1994, DOE's National Renewable Energy laboratory
broke the 30 percent barrier, which attracted interest from the space
industry. Most satellites today use these multi-junction cells.

Reaching 40 percent efficiency helps further President Bush's Solar
America Initiative (SAI) goals, which aims to win nationwide
acceptance of clean solar energy technologies by 2015. By then, it is
intended that America will have enough solar energy systems installed
to provide power to one to two million homes, at a cost of 5 to 10
cents per kilowatt/hour. The SAI is also key component of President
Bush's Advanced Energy Initiative, which provides a 22 percent
increase in research and development funding at DOE and seeks to
reduce our dependence on foreign sources of oil by changing the way
we power our cars, homes and businesses.

For more information, visit the Solar America Initiative website at:
http://www.eere. energy.gov/ solar/solar_ america/.