Incidence angle modifier coefficients

Dear Gentlemen,

When selected "Incidence angle modifiers" In "Collector and Receiver" page of SAM, "Solar position table" and "Collector incidence angle table" become inactive and are suppressed. Then the user can use the values in the "Incidence angle modifier coefficients" for LFR or CLFR.

Is it true ?
If it is not possible using the related values, what are they for ?

Kind regards,
Rahmi

Dear Rahmi,

SAM's linear Fresnel model offers three options for specifying the solar field's optical efficiency. Each option determines how the optical efficiency varies with sun position. The "solar position table" and "collector incidence angle table" options require a table of efficiency values that SAM uses to determine the field efficiency at different sun angles. When you choose one of those options, the table is active. The "incidence angle modifiers" option uses two polynomial equations to calculate an incidence angle modifier (IAM) at different solar angles instead of the table of efficiency values. SAM disables the table when you choose the IAM coefficients option because it does not use the values in the table for that option. The values are still visible on the Collector and Receiver page, but they are inactive because SAM does not use them. The values are still visible even when the table is inactive because of the way the user interface works, not because SAM is using them.

Best regards,
Paul.

Dear Mr. Paul Gilman,

Thank you very much for your reply.

I think I could not explain the subject.
There is no problem after selected the "incidence angle modifiers". After selecting the related
item, the table is made inactive and all the values in the table can not be used.

I would like to learn this :
After becoming inactive the table, that is, after selecting the "incidence angle modifiers", can the "incidence angle modifiers coefficients" values be used for CLFR system, without changing the current values of both "Transverse incidence angle modifier" and "Longitudinal incidence angle modifier" coefficients ?

We assume that the Novatec Solar CLFR system is used.

Many thanks for your patience.

Kind Regards,
Rahmi

Dear Rahmi,

Sorry I misunderstood your question.

Yes, the default values for the incident angle modifier coefficients represent the same Novatec system that the data in the Solar Position table represent. Please remember that the Novatec system is not a compact linear Fresnel system.

Best regards,
Paul.

Dear Mr. Paul Gilman,

Sorry, there is still a point I can not understand.

"Solar position table" and "Incidence angle modifiers" are for the same purpose.
I loaded the example LFR project in SAM and run for not only "Solar position table", but also
"Incidence angle modifiers". The results are below.
Everything other than "Optical characterization method" were remained without changing.

Could you please say us why the difference between their "Annual energy" is big.


*****
(CSP Linear Fresnel/Independent Power Producer)

Solar position table Incidence angle modifiers
{csp.lf.geom1.opt_mode} 0 2
Annual Energy 73,038,928 kWh 116,796,696 kWh
PPA price 20.80 ¢/kWh 13.01 ¢/kWh
LCOE Nominal 22.87 ¢/kWh 14.30 ¢/kWh
LCOE Real 18.19 ¢/kWh 11.38 ¢/kWh
Net present value ($) $ 21,737,086.00 $ 21,736,938.00
Capacity factor 17.5 % 28.1 %
Gross to Net Conv. Facto 0.96 0.97
Annual Water Usage 229,951 m3 353,775 m3
*****


Kind Regards,
Rahmi

Dear Mr. Paul Gilman,

There is a sentence such as "Please remember that the Novatec system is not a compact linear Fresnel system." in your last comment.

Please reread the "CLFR in SAM" topic in SAM-Forum.
I could not see a recommendation for "Incidence angle modifiers" in the comment.

Could you please advise us how "Incidence angle modifiers" can be calculated for CLFR system.


Kind Regards,
Rahmi