Selective solar absorber coating research at the CSIR (South Africa)

Abstract

A sol-gel technique has been established at a laboratory scale for low cost production of high efficient selective solar absorbers comprising a composite material of nano-structured carbon in a nickel oxide matrix. In order for these materials to be applied in real world scenarios it is necessary to extensively scale up the fabrication process to allow large area coatings. This can be done by adapting this sol-gel technique to large area deposition. In this project, we are undertaking research and development activities for three-years to make a 'Lab to Large scale' transition in order to eventually integrate into existing solar collectors for low cost domestic water heating in a rural area for social good. A spray coating technique has been used to deposit these C/NiO coatings on aluminum substrates. Preliminary optical results have shown absorptance of up to 90 %. The preparation and characterization as well as the process towards developing a large-area solar selective coating for low cost domestic heating will be discussed.