Solar metamaterial selective absorber for efficient energy harvesting: considering high-temperature absorption mechanisms

Solar selective absorbers are employed in concentrating solar power (CSP) and thermophotovoltaic (TPV) systems to enhance solar energy conversion efficiency. This study proposed a metamaterial absorber with a tungsten-silicon dioxide (W-SiO2) ring array structure, which can achieve an average absorptance of 0.9445. By combining optical measurements with the Lorentz-Drude model, the optical parameters of W under different temperatures are obtained and then applied in the analysis of metamaterial absorber. The results show that temperature variation significantly affects the optical properties of W, thus influencing the absorption performances and mechanisms of metamaterial. The effects of temperature and concentration ratio on absorption efficiency are investigated, and it reaches a maximum efficiency of 94.68 % within temperature range of 473–873 K. At high temperatures, the energy absorption efficiency can be improved by re-optimizing the geometry parameters. Additionally, an equivalent LC circuit model for the ring structure is developed to predict magnetic polariton resonance conditions of the absorber, and the LC model is also improved to describe the effect of temperature. The model exhibits maximum prediction deviations of 1.26 % at room temperature and 3.42 % at high temperature. These offer guidance for enhancing energy conversion efficiency of solar absorbers in high-temperature environments.