End loss

Dear Sir/Madam,
What is the definition of "End loss" in Parabolic trough simulation? How is it calculated? What is the difference between "Bellows shadowing" and "End loss"?
Thank you in advance.

Hello,

End loss is radiation that is reflected off of the end of the collector during hours when the radiation incidence angle is not normal to the collector aperture. Some of this radiation may be partially absorbed by the neighboring collector, and is called "end gain." For a description of how SAM calculates these values, see Section 2.3 of the parabolic trough reference manual ( PDF 3.7 MB ), starting on Page 21.

The bellows is a portion of the receiver designed to accommodate thermal expansion and contraction. Depending on its design, it may reduce the active absorbing area of the receiver. In SAM, you can represent this loss using the Bellows Shadowing input on the Receivers page.

Best regards,
Paul.