Hypervelocity impact testing of stretched lens array modules

As satellite power levels increase beyond 20 kW, increased attention is being devoted to increasing both array operating voltage and efficiency. Recently, the Stretched Lens Array has shown module efficiencies of over 27%. This array operates at sunlight concentration levels of about 8.5X, corresponding to an 8.5-cm-wide line-focus Fresnel lens focusing incident sunlight onto a row of 1.0-cm-wide high-efficiency solar cells. However, the effect of micrometeoroid impacts was not known either on the materials of construction or on the assembled module. Therefore, hypervelocity impact testing was conducted on components, modules and cell assemblies. Hypervelocity testing was done using 50 -100 μm diameter glass spheres at velocities above 10 km/sec. Initial tests on the silicone lens material held in tension, showed complete penetrations, but no tearing. Two-cell modules mounted on graphite substrates were also subjected to hypervelocity impact testing. These tests showed no arcing at voltages above 1000 V.