Lightweight Carbon Fiber Mirrors for Solar Concentrator Applications

TL;DR

This paper presents the development of lightweight carbon fiber reinforced polymer mirrors with nanometer-scale surface smoothing for solar concentrator applications, achieving high optical efficiency and potential for space photovoltaics.

Contribution

It introduces a novel nanometer-scale surface smoothing technique for CFRP mirrors, enhancing their optical quality for solar concentrator use.

Findings

Surface roughness reduced from ~3 μm to ~5 nm RMS after smoothing.

Mirrors achieved 78% optical efficiency in an 11x concentrator setup.

Potential for high specific power in space photovoltaics.

Abstract

Lightweight parabolic mirrors for solar concentrators have been fabricated using carbon fiber reinforced polymer (CFRP) and a nanometer scale optical surface smoothing technique. The smoothing technique improved the surface roughness of the CFRP surface from ~3 {\mu}m root mean square (RMS) for as-cast to ~5 nm RMS after smoothing. The surfaces were then coated with metal, which retained the sub-wavelength surface roughness, to produce a high-quality specular reflector. The mirrors were tested in an 11x geometrical concentrator configuration and achieved an optical efficiency of 78% under an AM0 solar simulator. With further development, lightweight CFRP mirrors will enable dramatic improvements in the specific power, power per unit mass, achievable for concentrated photovoltaics in space.