An LED-Based Solar Simulator for Research, Development, and Testing of Photovoltaic Space Power Systems

Solar cells are the critical power source for the majority of space missions. The advancement from single junction silicon cells to current, state-of-the-art, triple junction, germanium cells enabled greater mission power per weight, stowed volume and deployed area. Near-term, advanced solar cell technologies will range from 4 to 6 junctions, and include a variety of band gaps. Solar cell testing is critical to space missions. Every solar cell is tested at the cell level under continuous light and at the panel, wing and sometimes spacecraft level multiple times under LAPSS. Current test methods calibrate the light source by measuring the current output of each junction and adjusting the source accordingly. Today's sources are a combination of lamps and filters. As cells with more the 3 junctions come into test, more flexible sources of narrower bands will be needed and current methods will have extreme difficulty, complexity and expense trying to keep up with the variety of near-term advanced solar cell designs. We propose a solid state illumination source with enough discrete source wavelengths to be flexible enough to be calibrated to any number of junctions, up to 6, for continuous cell testing. In addition, this source would be cost effective enough to allow many sources connected together to perform large area testing, pulsed or continuous, for panel and wing level testing. Calibration would follow similar methods to the current practice, but would be simplified through a software interface.

This program will benefit all NASA missions that will use solar cells with more than 3 junctions. The illumination source may also replace existing 3 junction illumination sources. The usefulness of the proposed source across multiple numbers of junctions and larger than single cell areas means there is potentially broad application of this technology for all testing of future solar cell technologies at the cell, string, panel, wing and spacecraft level.

The benefits above apply to non-NASA applications as well. The proposed source could be used by all NASA contractors and commercial prime spacecraft suppliers for testing of cells with more than 3 junctions at the cell, string, panel, wing and spacecraft levels. There is also potential application to terrestrial applications, particularly where the flexibility of the proposed design helps scientists and test engineers determine additional wavelength dependence of the device under test than would be possible with a less flexible, traditional lamp-based method.

This is early/mid-stage (TRL 4) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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