Solar

Back to Proven PV for Satellite

The latest Boeing satellite, the 702 Galaxy IIIC, has returned to the proven efficiency of triple junction solar cells, which can harness much more available light than normal silicon-based photovoltaics (PV).

St. Louis, Missouri – October 25, 2002 [SolarAccess.com] The 702’s solar cells were made by Spectrolab, a subsidiary of Boeing Satellite Systems. They are extremely efficient because of their design and the materials used in their construction. The design is called triple-junction, because they have three separate layers, each of which absorbs a different portion of the solar spectrum. “They are terrific technology,” said Richard Esposito of Boeing. “The quality of their design, materials and manufacture is such that they are surpassing predictions that were based on the manufacturing specs.” When introduced in the late 1990s, the Boeing 702 featured solar arrays with concentrators running the length of the solar wing. These were intended to concentrate sunlight onto the surface of the solar cells. Boeing’s use of triple junction cells are a departure from concentrator technology which they found last September to not have the optical qualities they had predicted, said Esposito. Boeing subsequently discontinued the use of solar array concentrators in favor of a flat planar array similar to the one successfully used on their midsize model, the Boeing 601. In the 702’s case, the new flat arrays are longer and made of higher-efficiency cells, all of which is needed to generate the required higher power levels for these large satellite payloads. Owned by PanAmSat of Wilton, Connecticut, the 702 will be used to deliver video, VSAT and broadcast services, as well as direct-to-home services for DIRECTV Latin America. The solar arrays are designed to provide at least 15 kW of power throughout its 15-year design life. “The flat planar design has been flight proven over many successful missions. The improved triple-junction gallium arsenide solar cells represent an advanced state-of-the-art in space solar power,” Esposito said. “Spectrolab is continuing to develop even more efficient solar cells for future satellites.”