New solar-selective CSP receiver coatings studied by environmental in situ methods

The development of solar-selective CSP receiver coatings with high-temperature and environmental stability requires new concepts of design and in operando monitoring. Solar receiver tubes are a key component of solar thermal power plants. The increase of their operation temperature from today’s maximum of 550°C to about 800°C could increase the CSP efficiency by approximately 15 to 20% and improve the competiveness of this technology compared to other ones of carbon-free electricity generation. Potential alternatives to fast degrading state-of-the-art pigment paint receiver tube coatings are based on refractive metal carbides, nitrides, and oxides because of their high thermal stability and oxidation resistance. New types of solar-selective coatings were studied in situ at temperatures of up to 830°C by Rutherford backscattering spectrometry, Raman spectroscopy, and spectroscopic ellipsometry within a cluster tool. They include carbon- and oxynitride-absorber based multilayers as well as a solarselective transmitter based on a transparent conductive oxide.

Financial support by the EU, grant No. 645725, project FRIENDS2, and the HGF via the W3 program (S.G.) is gratefully acknowledged.