A high-performance spectrally-selective solar absorber based on a yttria-stabilized zirconia cermet with high-temperature stability

• Published in: Energy & environmental science Vol. 8; no. 10; pp. 3040 - 3048
• Main Authors: Cao, Feng, Kraemer, Daniel, Tang, Lu, Li, Yang, Litvinchuk, Alexander P, Bao, Jiming, Chen, Gang, Ren, Zhifeng
• Format: Journal Article
• Language: English
• Published: United States Royal Society of Chemistry 01.01.2015
• Subjects: Absorptance; Absorptivity; Cermets; Emittance; Operating temperature; Partial pressure; solar (photovoltaic), solar (thermal), solid state lighting, phonons, thermal conductivity, thermoelectric, defects, mechanical behavior, charge transport, spin dynamics, materials and chemistry by design, optics, synthesis (novel materials), synthesis (self-assembly), synthesis (scalable processing); Spectra; Thermal stability; Yttria stabilized zirconia
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/c5ee02066b

Spectrally-selective solar absorbers are widely used in solar hot water and concentrating solar power (CSP) systems. However, their performance at high temperatures (>450 degree C) is still not satisfactory due to high infrared (IR) emittance and lack of long-term thermal stability. Here, we explore yttria-stabilized zirconia (YSZ) cermet-based spectrally-selective surfaces for high-temperature solar absorber applications. The developed multilayer selective surface comprises two sunlight-absorbing W-Ni-YSZ cermet layers with different W-Ni volume fractions inside the YSZ matrix, two anti-reflection coatings (ARCs), and one tungsten IR reflection layer for reduced IR emittance and improved thermal stability, deposited on a polished stainless steel (SS) substrate. The fabricated solar absorbers are tested for their long-term thermal stability at 600 degree C. We find a distinct change in the surface morphology of the solar absorbers when oxygen is highly deficient in the YSZ-ARC layers. The oxygen deficiency can be effectively overcome through increasing the oxygen partial pressure during sputtering, which leads to a stable solar absorber with a solar absorptance of similar to 0.91 and a total hemispherical emittance of similar to 0.13 at 500 degree C. Those values are obtained at the actual operating temperature using an absolute and direct method that measures the total hemispherical emittance with high accuracy. In contrast, most reports on solar absorber development in the literature to date use only near room-temperature spectroscopy techniques that have been shown to significantly underestimate the total hemispherical emittance. This makes our experimentally demonstrated total hemispherical emittance value the lowest ever reported for a high-temperature stable solar absorber with solar absorptance above 0.9.