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

Solar thermal absorber coatings play an important role in the opto-thermal efficiency of receivers Concentrated Power (CSP). Two standard figures merit are solar absorptance ?sol and emittance ?th, derived from spectral directional hemispherical reflectance measurements at room temperature. These two allow comparing coating formulations terms performance durability. In this study, a black selective optically characterized by different laboratories to compare datasets, ?th calculations. The comparison includes various benchtop spectrophotometers operating UV-VIS-NIR Infrared ranges as well three commercial portable reflectometers/emissometers. A good agreement is found between nine parties participating intercomparison campaign. value 96.6 ± 0.2%, while 94.5 0.4%. For emittance, data concatenated integrated 0.3 16 ?m. calculated 650 °C 80.8 3.8%, 25.0 0.5%.