High altitude AM0 testing of PV concentrator lens elements

Recently, the NASA Lewis Research Center modified its Lear High Altitude Test Facility to fly two prototype ENTECH minidome Fresnel lens photovoltaic concentrator elements. The tests were highly successful, and the results verified the ability of the Lear High Altitude Facility to measure the optical performance of individual concentrator lens elements and concentrator/cell combinations at near AM0 insolation conditions. The two concentrator lenses flown achieved optical efficiencies, based on a gallium arsenide concentrator cell response, of 89.8% and 90.0%. The flights demonstrated the ability of the aircraft, to maintain the pointing accuracy required to obtain useful data. With proper alignment of the collimating tube and the pilot´s sunsight, this facility could easily maintain a pointing accuracy of ±0.5° for a sufficiently long time to obtain accurate, reproducible results