Realization of an efficient wide-angle solar selective absorber via the impedance matching

Constructing the solar absorber with high omnidirectional absorption has great potential for enhanced solar energy conversion. Although varieties of strategies have been carried out to enhance the solar absorption at the near-normal incidence and achieve the selective solar absorbers (SSAs) with high optical performance, the wide-angle absorber is rarely investigated. Here, we experimentally demonstrated a wide-angle high absorption solar selective absorber configurated with the W–SiO₂ cermet-based quasi-optical cavity structure for effective solar harvesting. It can realize a wideband absorption in the wavelength range of 300–1400 nm at the normal incidence, and maintain the average omnidirectional absorption of ∼95% over the incident angle ranges from 8 to 80°, which ascribes to the impedance matching between the absorber and the free space at a large incident angle. The SSA also demonstrates a large solar absorption of around 70% at the incident angle of 80°. A remarkable temperature increase of ∼40 °C relative to ambient temperature was achieved for the SSA directly exposed to the outdoor sunshine without solar concentration in the subtropical city of Shenzhen.