Laboratory intercomparison of solar absorptance and thermal emittance measurements at room temperature

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

Solar Energy Materials and Solar Cells Vol. 238, pp. 111579-1 - 111579-15

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 α_sol and thermal emittance ε_th, 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 α_sol and thermal emittance ε_th 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 α_sol value is 96.6 ± 0.2%, while the solar selective coating α_sol 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 ε_th value calculated at 650 °C is 80.8 ± 3.8%, while the solar selective coating ε_th 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]