ESA supported the development and design of this flexible, ultra-thin solar cell to deliver the best power-to-weight ratio for space missions. A breakthrough that will hopefully be transferred to commercial solar power in the future.

Only 0.02mm thick – thinner than a human hair – the solar cell prototypes were developed by Azur Space Solar Power in Germany and TF2 in the Netherlands; the cell in the photo is tf2. The project was supported by the European Space Agency, which studies new technologies for space.

With a efficiency up to 32% at end of life, solar cells were produced using a technique called “epitaxial takeoff“, Which means they peeled off the germanium substrate layer they were originally placed on, so the expensive material can be reused.

Triple and quadruple junction solar cells have been manufactured. This means that they are made of three or four different layers of material, optimized to use the different wavelengths of light that make up the solar spectrum.

These thinner-than-paper solar cells could be harnessed for future ESA satellites or high-altitude pseudo-satellites (HAPS) – unmanned planes or balloons to perform satellite-like tasks from the upper atmosphere.

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