FLORIDA TODAY Space Online
September 17, 1997
SOLAR CELL EFFICIENCY NEARLY DOUBLED BY HUGHES' SPECTROLAB
Hughes Space and Communications Co. news release
LOS ANGELES -- Spectrolab Incorporated, a unit of Hughes Electronics Corporation, has announced the successful operation of a revolutionary dual-junction gallium arsenide solar cell which will nearly double the efficiency of traditional silicon cells used on spacecraft solar array panels.
Spectrolab's gallium arsenide dual-junction solar cells are the result of more than 10 years of development, but with the launch of PanAmSat Corporation's PAS-5 satellite on Aug. 27, the cells made their first voyage into space and are the first in use on a commercial communications satellite.
"Because the power is nearly doubled, these dual-junction cells enable us to provide solar panels which are either twice the power or half the weight," said Dieter Zemmrich, president of Spectrolab. "This advanced technology enables our customers to be more flexible in their satellite design, a benefit which has great competitive advantage."
A solar cell is basically a semiconductor with the ability to convert the light from the sun into electrical energy. The dual-junction gallium arsenide solar cells can convert 21.6 percent of the sun's energy into power, as compared to the traditional silicon solar cells, which can convert only 12.3 percent.
Dual-junction solar cells measure approximately 4.2 square inches in area and 0.0055 inches in thickness. The cells are "grown," atom by atom, in an epitaxial growth chamber using 100-millimeter diameter single crystal germanium wafers as a supporting substrate. The germanium wafer provides the crystalline structure upon which to "grow" the single crystal solar cell layer.
Two solar cells are layered on top of each other, and because each converts a different part of the light spectrum, the solar cell can more efficiently convert sunlight into electrical power. As the sun's ray hits the top layer of gallium indium phosphide, short wavelengths are converted into electrical power. Because gallium indium phosphide is transparent to long wavelengths, these actually pass through to the gallium arsenide layer, where they too are onverted into electrical power, thus creating the second or dual junction. This simultaneous function is unique to the dual-junction solar cells and is the basis for the increased efficiency.
The PAS-5 satellite, built by Hughes Space and Communications Company, uses nearly 15,000 dual-junction gallium arsenide solar cells to convert the sun's rays into 10 kilowatts of power at beginning of life, a substantial increase over the 4.8 kilowatts provided by a standard HS 601 satellite. PAS-5's 10 kilowatts will provide the power necessary to broadcast direct-to-home and other television services in Latin America for 15 years.
Spectrolab Incorporated is headquartered in Sylmar, Calif., and is a leading supplier of solar cells, solar panels, searchlights and solar simulators. The company, founded in 1956, has been supplying solar array panels to the space industry for nearly 40 years. Pioneer 1, launched in 1958, carried Spectrolab's first body-mounted panels.
The following year, Explorer 6 became the first satellite to use Spectrolab's solar arrays instead of body-mounted panels. Hughes acquired Spectrolab in 1975, and it is a major supplier of solar cells to another Hughes
Electronics unit, Hughes Space and Communications Company, the world's leading commercial communications satellite manufacturer, having built nearly 40 percent of those in operation.
Spectrolab is a unit of Hughes Electronics Corporation. The earnings of Hughes Electronics are used to calculate the earnings per share attributable to GMH (NYSE symbol) common stock.Compliments of Proposition One Committee