Summary:
Solar thermal absorber coatings play an important role in the opto-thermal efficiency of receivers in Concentrated Solar Power (CSP). Two standard figures of merit are the solar absorptance αsol and thermal emittance εth, derived from spectral directional hemispherical reflectance measurements at room temperature. These two figures of merit allow comparing coating formulations in terms of performance and durability.
In this study, a black coating and a solar selective coating are optically characterized by different laboratories to compare spectral datasets, solar absorptance αsol and thermal emittance εth calculations. The comparison includes various benchtop spectrophotometers operating in the UV-VIS-NIR and Infrared spectral ranges as well as three commercial portable reflectometers/emissometers.
A good agreement is found between the nine parties participating in this intercomparison campaign. The black coating αsol value is 96.6 ± 0.2%, while the solar selective coating αsol value is 94.5 ± 0.4%. For the thermal emittance, spectral data is concatenated and integrated from 0.3 to 16 μm. The black coating εth value calculated at 650 °C is 80.8 ± 3.8%, while the solar selective coating εth value calculated at 650 °C is 25.0 ± 0.5%.
Spanish layman's summary:
Un recubrimiento negro y un recubrimiento selectivo solar (SSC) han sido caracterizado ópticamente por nueve laboratorios diferentes. La absorción solar se determina con una desviación del <0,5%, mientras que el cálculo de la emitancia térmica a 650ºC varía un 3,8% para el recubrimiento negro y un 0,5% para el SSC.
English layman's summary:
A black coating and a solar selective coating (SSC) are optically characterized by nine different laboratories. Solar absorptance is determined with <0.5% deviation while thermal emittance calculations at 650ºC vary by 3.8% for the black coating and by 0.5% for the SSC.
Keywords: Concentrated solar power; Solar thermal; Absorber coating; Solar absorptance; Thermal emittance
JCR Impact Factor and WoS quartile: 6,900 - Q1 (2022); 6,300 - Q1 (2023)
DOI reference:
https://doi.org/10.1016/j.solmat.2022.111579
Published on paper: May 2022.
Published on-line: January 2022.
Citation:
S. Caron, L. Herding, Y. Binyamin, M. Baidossi, Y. Vinetsky, A. Morales, C. Hildebrandt, R. Reoyo-Prats, O. Faugeroux, A. Agüero, S. Rodríguez, F. Sutter, M. Röger, F. Manzano-Agugliaro, Laboratory intercomparison of solar absorptance and thermal emittance measurements at room temperature. Solar Energy Materials and Solar Cells. Vol. 238, pp. 111579-1 - 111579-15, May 2022. [Online: January 2022]
Download this paper