Recent Progress on the Stretched Lens Array (SLA)

At the last Space Photovoltaic Research and Technology Conference, SPRAT XVII, held during the fateful week of 9/11/01, our team presented a paper on the early developments related to the new Stretched Lens Array (SLA), including its evolution from the successful SCARLET array on the NASA/JPL Deep Space 1 spacecraft. Within the past two years, the SLA team has made significant progress in the SLA technology, including the successful fabrication and testing of a complete four-panel prototype solar array wing (Fig. 1). The prototype wing verified the mechanical and structural design of the rigid-panel SLA approach, including multiple successful demonstrations of automatic wing deployment. One panel in the prototype wing included four fully functional photovoltaic receivers, employing triple-junction solar cells. These receivers were fully encapsulated to enable high-voltage operation in space plasma, and the receivers all passed 500 V wet hi-pot testing. Complete lens/receiver units were accurately tested for performance using a large-area pulsed solar simulator (LAPSS), calibrated with reference cells flown by NASA Glenn on their Lear Jet photovoltaic test facility. The best lens/receiver unit achieved 27.5% net efficiency at 28C cell temperature under AM0 sunlight. The measured mass and performance of the prototype wing accurately matched predictions. The same performance and mass model shows that a 7 kW wing, using the same rigid-panel technology demonstrated on the prototype wing, will achieve these unprecedented performance metrics at beginning of life (BOL) on geostationary orbit (GEO, with 75C cell temperature): >180 W/kg specific power >300 W/m 2 areal power density