Update FCR method to replicate ATB

[janinefreeman]

It may be useful to update the FCR method in SAM so that it replicates what the ATB is doing

[janinefreeman]

This may be a necessary improvement as part of the geothermal ATB matching process this year.

[sjanzou]

Alignment with equations at https://atb.nrel.gov/electricity/2024/equations_&_variables

[brtietz]

Note: ATB LCOE equations include fuel costs, but FCR method in SAM does not. This is a key input for computing LCOE for the custom generation system.

[brtietz]

Additional considerations from 10/8 discussion:

• Variable name changes will require some version upgrade script work
• Will require a significant help rewrite
• Might be good to create a new compute module to get the FCR calculation out of lk and into ssc for PySAM accessibility

No particular rush on this, just get to it before the next release.

[brtietz]

See https://atb.nrel.gov/electricity/2024/equations_&_variables for ATB equations