Optical efficiency in LFR

I'm modeling a LFR plant in SAM. When I have to select the optical efficiency, in "Collector and receiver" section, i have three options: Solar position table, Collector incidence angle table and IAM. I calculate the solar position table with a ray tracing software, and also the IAM, and with the two methods, I compare the result in production and the difference is high (almost double using IAM). I don't understand this, because I use the same reference that SAM in the calculate of Solar position table, and also to calculate the IAM. i don't know if there is a problem with the solar position table or IAM, or i'm doing something wrong (i've revised the calculate and i don't find nothing wrong). In the Solar position table, in the boiler section, there are difference with the superheater section (the azimuth and zenith angle are in bold type in superheater, but in boiler not). I don't know if this is a problem.

Thanks

Dear Jose,

The different options for characterizing the solar field optical performance should give similar results if the inputs are consistent.

Please refer to the diagram in the SAM Help system's "Collector and Receiver" topic in the CSP Linear Fresnel chapter to verify that the transverse and longitudinal IAM coefficients are correct.

Best regards,
Paul.