I have a reflectance data of my solar absorber coating from UV-Vis, I want to calculate the solar absorbance of my coating using standard reference spectrum AM 1.5 and thermal emittance of thesame coating using blackbody radiation spectrum.
Is it assumed that the transmittance T of the coating is zero?
If that is the case, you should have (sorry in advance if I dont use the exact metrologic terminology, I am taking a risk here):
1=T+R+A=R+A,
where A is the absorptance and R the reflectance (specular and diffuse). I think that the equation will be similar for the solar absorptance, but you will use in this case the solar reflectance, the ratio of the integration of R*AM1.5 on the integration of AM1.5, with both integration on the wavelength interval defining AM1.5.
I am not 100% about the emittance, but I think that it is similar to the calculation of the solar absorptance above where you replace AM1.4 with a blackbody spectrum.
I hope it makes sense.
Hello Mutawalli,
in the thermal equilibrium the spectral emission of a black body is equal to the absorbance. So, if you have one, you have the other for a given temperature. The reflectivity gives the difference if the over all absorption is
Thank you Daniel Poitras, the answer you provided really makes sense and it helps a lot. But I also need clarification on the wavelength intervals. I measured the reflectance in the wavelength intervals of 300-2500 nm. So am I going to integrate both both the measured reflectance and the AM 1.5 within 300-2500 nm?
Thank You
Best regards.
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