Round-robin test results on the temperature stability of a black chrome coating

As part of Task X in the Solar Heating and Cooling Programme of the International Energy Agency, methods for the lifetime assessment of solar absorber coatings have been investigated. In a first step, the degradation caused by the individual contributing factors (e.g. temperature, moisture, 502) was tested for each factor separately. The results of the temperature tests in particular could be used for a lifetime estimation with respect to this single degradation factor. The errors in the measured degradation of the coatings, as detected by the changes of the solar absorptance and the thermal emittance, and their influence on the estimated lifetime, were investigated empirically in a Round Robin Test. This was performed on the same black chrome coating by seven different laboratories following the same test procedures. The results agree surprisingly well and are very encouraging for the definition of a recommended standard procedure for the assessment of the thermal stability of solar absorber coatings in the future.