Improvement of solar absorption using submicrometric gratings

The paper demonstrates a rigorous modeling approach for 1D microstructured absorbing multi-layers for the receivers of CSP (Concentrated Solar Power), taking into account both absorption of the incident solar energy and the emissivity while considering receivers temperature. From an optimized multilayers structure achieving high absorption, the authors demonstrate that 1D sub wavelength period gratings could increase further the absorption and thus the yield of the Concentrated Solar Power system. The authors used C-method (Chandezon Method) to optimize 1D grating profile. Experimental demonstration on Silicon wafers combining writing grating and absorptive layers deposition are also presented. Experimental results are presented and absorbance enhancement of almost 2% are achieved with values of 96.5% in the visible and UV range. The results are promising for the design of future and competitive solar absorbers for CSP since the microstructuring fabrication approach can be applied to non-planar substrates such as tubes, which are the receivers of the CSP.