Novel Mo-Si₃N₄ based selective coating for high temperature concentrating solar power applications

A novel selective coating material based on Mo-Si₃N₄ has been investigated for the first time. Accurate combination of the individual component layers based on optical simulations and precise control of layers thickness and composition leads to high solar absorptivity (α _Sol=0.926) and low thermal emissivity (ε_{25 C}=0.017) on a silver film, resulting in a high solar thermal energy conversion efficiency. The tandem absorber is stable in moderate vacuum at temperatures above 600 C showing low emissivity (estimated value at 600 C is ε _{600 C}=0.109) evidencing its relevance for high temperature solar selective applications. A full optical and thermal analysis of a parabolic trough concentrator (PTC) system confirmed the potential of the novel coating material to be used for CSP technology.