Angular solar absorptance and thermal stability of Mo–SiO2 double cermet solar selective absorber coating

• Published in: Solar energy 2015-05, Vol.115, p.341-346
• Main Authors: Zheng, Liqing, Zhou, Fuyun, Zhou, Zhuangda, Song, Xingwang, Dong, Guobo, Wang, Mei, Diao, Xungang
• Format: Article
• Language: English
• Subjects: Angular solar absorptance; Mo–SiO2; Solar selective coating; Thermal stability
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2015.02.013

•A wide-angle absorptance coating with α=0.945 was obtained.•Annealing at 600°C in vacuum is beneficial to enhance thermal stability.•Degradation of conversion efficiency is occurred after annealing at 800°C.•Degradation can be attributed to grain growth and inter-diffusion. In this paper, the angular solar absorptance of Mo–SiO2 double cermet solar selective absorber coating was simulated based on the deduced optical constants and calculated from measured reflectance spectra in the wavelength range 0.25–2.5μm for incidence angles between 0° and 75° by interval of 15°. It was found that Mo–SiO2 double cermet solar selective absorber with angular absorptance α=0.945 from 0° up to 60° is a wide-angle absorptance coating. The effect of thermal annealing on optical properties, microstructure and morphology of Mo–SiO2 double cermet solar selective coating was investigated. The annealing in vacuum at 600°C results in grain refinement of Mo particle, denser cermet layer and photo-thermal conversion efficiency increasing of 0.6%. Annealing at 800°C leads to grain growth of polycrystalline structure Mo, inter-diffusion in cermet layer and the photo-thermal conversion efficiency decreasing of 1.3%.