High efficiency concentrated solar power plant receivers using periodic microstructured absorbing layers

- Combining gratings and thin absorptive layers provides highly selective absorbers for CSP plants.
- Optical behavior of textured multilayer systems are modeled using Chandezon method.
- Microstructured absorbers are fabricated by photolithography followed by PVD steps.

This study presents a rigorous modeling approach for 1D microstructured absorbing multi-layers for Concentrated Solar Power (CSP) receivers, taking into account both the absorption of the incident solar energy as well as the emissivity for the desired receiver temperature. Based on an optimized multilayer structure achieving high absorption, the authors demonstrate that 1D sub-wavelength period gratings can further increase the absorption and thus the efficiency of the CSP system. The C-method (Chandezon Method) is used to theoretically optimize the 1D grating profiles. An experimental demonstration of the combination of lithographic grating fabrication and absorptive layer deposition using standard silicon wafers as substrates is also presented. Experimental results show 96.5% absorption in the visible and UV range, representing an enhancement of almost 2% in comparison to non-structured coatings. Those results are promising for the design of future and competitive solar absorbers for CSP, especially since the microstructure fabrication approach can be applied to non-planar substrates such as tubes typically used as receivers in CSP plants.