Description

Addresses NREL#421 for SAM Economic Models

Testing & Verification

1. Added new unit tests
2. Added new example example_SAM-single-owner-PPA-4.: 50 MWe with Royalties
3. Tested in web interface
4. Manually tested/sanity-checked
   1. 

TODO:

1. FIXME incorrect calculation:

   GEOPHIRES/src/geophires_x/EconomicsSam.py

   Lines 176 to 181 in 85a323e

   	royalty_rate = model.economics.royalty_rate.quantity().to('dimensionless').magnitude
   	ppa_revenue_row = _cash_flow_profile_row(cash_flow, 'PPA revenue ($)')
   	royalties_unit = sam_economics.royalties_opex.CurrentUnits.value.replace('/yr', '')
   	sam_economics.royalties_opex.value = [
   	quantity(x * royalty_rate, 'USD').to(royalties_unit).magnitude for x in ppa_revenue_row
   	]

2. CHANGELOG entry
3. Validate that excluding Year 0 (0 revenue) is correct for calculating NPV

   GEOPHIRES/src/geophires_x/Economics.py

   Lines 3359 to 3364 in a60199c

   	# ignore pre-revenue year(s) (e.g. Year 0)
   	pre_revenue_years_slice_index = model.surfaceplant.construction_years.value
   	average_annual_royalties = np.average(
   	self.sam_economics_calculations.royalties_opex.value[pre_revenue_years_slice_index:]
   	)

4. Slice based on pre-revenue (construction) years instead of hardcoding: a60199c
5. Clarify taxes for royalties: a0d0c38
6. Add a test for combined royalties and add-ons: a782cd7
7. Royalties schedule (instead of fixed value)
8. Update documentation
9. Royalty collector economics
10. Include annual average in GEOPHIRES OPEX (separate line item + include in total)
11. Reconcile with fixed total OPEX