Divide (a) the heat absorbed by the material flowing through the cylindrical-parabolic collector (mass X temperature rise X specific heat), adding (mass X latent heat) if a phase change occurs, by (b) the solar energy received by the collector. Both (a) and (b) can be measured by off-the-shelf equipment.

Thanks for your answer.

Dear Sara;

I recommend to use the book " Handbook of Solar Energy Theory, Analysis and Applications" published by G.N. Tiwari •Arvind Tiwari Shyam.

Really; it is very good and definitely it will cover your request.

Best regards.

Thank you very much Mister Abdullateef Ahmed for your best information.

Article Thermal and optical efficiency investigation of a parabolic ...

https://www.iasj.net/iasj?func=fulltext&aId=41141