AFRL Advances SBIR-Developed Solar Cell Technology

  • Published
  • By Eva Blaylock
  • Space Vehilces Directorate
KIRTLAND AIR FORCE BASE, N.M. --  Engineers from AFRL and United Solar Ovonic, LLC, established a new program geared towards expanding technology developed under previous Small Business Innovation Research (SBIR) projects. As part of implementing this venture, AFRL signed an 18-month contractual option outlining the development of new solar cell technology tailored for space and airship vehicle use. The option, which carries a price tag under $2 million, will facilitate efforts to engineer next-generation solar arrays designed specifically for Air Force (AF) missions. These cutting-edge arrays will be lighter, more stowable, and less costly than the products currently in use.

The AF need for high-efficiency, ultralightweight amorphous silicon (a-Si) solar cells prompted AFRL to leverage United Solar Ovonic's existing product in creating one conducive to space use. The product--a terrestrial solar cell optimized for use on earth and deposited on a heavy, 5 mil stainless steel substrate--reflects the company's UNI-SOLAR technology. 

UNI-SOLAR space photovoltaic (PV) products offer an ultralight, low-cost alternative to conventional space PV modules made of crystalline silicon or gallium arsenide. Originally developed for terrestrial applications, UNI-SOLAR features triple-junction modules constructed of a-Si-based thin-film alloys and deposited on a 5 mil flexible stainless steel substrate. Space cells employing polymeric substrates have already demonstrated specific powers exceeding 1000 W/kg, a significant improvement over current capability. Since high specific power, radiation hardness, and superior high-temperature performance are all requirements for space applications, the inherent properties of a-Si make it an attractive material for space and airship vehicle use. 

Solar cells deposited on thin stainless steel foil are currently undergoing test in AFRL missions such as TacSat-2, an experimental satellite that launched in December 2006, while solar cells deposited on the new polymer substrates will fly as components of upcoming experimental missions.