Calculate and display WACC for SAM Economic Model

Author: softwareengineerprogrammer

src/geophires_x/Economics.py

@@ -4,8 +4,8 @@
 import numpy_financial as npf
 import geophires_x.Model as Model
 from geophires_x import EconomicsSam
-from geophires_x.EconomicsSam import calculate_sam_economics, SamEconomics
-from geophires_x.EconomicsUtils import BuildPricingModel
+from geophires_x.EconomicsSam import calculate_sam_economics, SamEconomicsCalculations
+from geophires_x.EconomicsUtils import BuildPricingModel, wacc_output_parameter
 from geophires_x.OptionList import Configuration, WellDrillingCostCorrelation, EconomicModel, EndUseOptions, PlantType, \
     _WellDrillingCostCorrelationCitation
 from geophires_x.Parameter import intParameter, floatParameter, OutputParameter, ReadParameter, boolParameter, \
@@ -442,7 +442,7 @@ def CalculateLCOELCOHLCOC(econ, model: Model) -> tuple:
             LCOH = LCOH * 2.931  # $/Million Btu
     elif econ.econmodel.value == EconomicModel.SAM_SINGLE_OWNER_PPA:
         # Designated as nominal (as opposed to real) in parameter tooltip text
-        LCOE = econ.sam_economics.lcoe_nominal.quantity().to(convertible_unit(econ.LCOE.CurrentUnits.value)).magnitude
+        LCOE = econ.sam_economics_calculations.lcoe_nominal.quantity().to(convertible_unit(econ.LCOE.CurrentUnits.value)).magnitude
     else:
         # must be BICYCLE
         # average return on investment (tax and inflation adjusted)
@@ -852,7 +852,7 @@ def __init__(self, model: Model):
             PreferredUnits=PercentUnit.TENTH,
             CurrentUnits=PercentUnit.TENTH,
             ErrMessage=f'assume default discount rate ({discount_rate_default_val})',
-            ToolTipText="Discount rate used in the Standard Levelized Cost Model. "
+            ToolTipText="Discount rate used in the Standard Levelized Cost Model and SAM Economic Models. "
                         "Discount Rate is synonymous with Fixed Internal Rate. If one is provided, the other's value "
                         "will be automatically set to the same value."
         )
@@ -1519,7 +1519,7 @@ def __init__(self, model: Model):
         self.InputFile = ""
         self.Cplantcorrelation = 0.0
 
-        self.sam_economics: SamEconomics = None
+        self.sam_economics_calculations: SamEconomicsCalculations = None
 
         sclass = str(__class__).replace("<class \'", "")
         self.MyClass = sclass.replace("\'>", "")
@@ -1775,6 +1775,8 @@ def __init__(self, model: Model):
             CurrentUnits=PercentUnit.PERCENT
         )
 
+        self.wacc = self.OutputParameterDict[self.wacc.Name] = wacc_output_parameter()
+
         # TODO this is displayed as "Project Net Revenue" in Revenue & Cashflow Profile which is probably not an
         #   accurate synonym for annual revenue
         self.TotalRevenue = self.OutputParameterDict[self.TotalRevenue.Name] = OutputParameter(
@@ -2755,10 +2757,10 @@ def Calculate(self, model: Model) -> None:
 
         non_calculated_output_placeholder_val = -1
         if self.econmodel.value == EconomicModel.SAM_SINGLE_OWNER_PPA:
-            self.sam_economics = calculate_sam_economics(model)
-            self.ProjectNPV.value = self.sam_economics.project_npv.quantity().to(
+            self.sam_economics_calculations = calculate_sam_economics(model)
+            self.ProjectNPV.value = self.sam_economics_calculations.project_npv.quantity().to(
                 convertible_unit(self.ProjectNPV.CurrentUnits)).magnitude
-            self.ProjectIRR.value = self.sam_economics.project_irr.quantity().to(
+            self.ProjectIRR.value = self.sam_economics_calculations.project_irr.quantity().to(
                 convertible_unit(self.ProjectIRR.CurrentUnits)).magnitude
 
             self.ProjectVIR.value = non_calculated_output_placeholder_val  # TODO SAM VIR

src/geophires_x/EconomicsSam.py

@@ -2,7 +2,6 @@
 
 import json
 import os
-import pprint
 from dataclasses import dataclass, field
 from functools import lru_cache
 from math import isnan
@@ -28,15 +27,15 @@
 
 from geophires_x import Model as Model
 from geophires_x.EconomicsSamCashFlow import _calculate_sam_economics_cash_flow
-from geophires_x.EconomicsUtils import BuildPricingModel
+from geophires_x.EconomicsUtils import BuildPricingModel, wacc_output_parameter
 from geophires_x.GeoPHIRESUtils import is_float, is_int
 from geophires_x.OptionList import EconomicModel, EndUseOptions
 from geophires_x.Parameter import Parameter, OutputParameter, floatParameter
 from geophires_x.Units import convertible_unit, EnergyCostUnit, CurrencyUnit, Units, PercentUnit
 
 
 @dataclass
-class SamEconomics:
+class SamEconomicsCalculations:
     sam_cash_flow_profile: list[list[Any]]
 
     lcoe_nominal: OutputParameter = field(
@@ -64,6 +63,8 @@ class SamEconomics:
         )
     )
 
+    wacc: OutputParameter = field(default_factory=wacc_output_parameter)
+
 
 def validate_read_parameters(model: Model):
     def _inv_msg(param_name: str, invalid_value: Any, supported_description: str) -> str:
@@ -107,11 +108,11 @@ def _inv_msg(param_name: str, invalid_value: Any, supported_description: str) ->
 
 
 @lru_cache(maxsize=12)
-def calculate_sam_economics(model: Model) -> SamEconomics:
+def calculate_sam_economics(model: Model) -> SamEconomicsCalculations:
     custom_gen = CustomGeneration.new()
     grid = Grid.from_existing(custom_gen)
     utility_rate = UtilityRate.from_existing(custom_gen)
-    single_owner = Singleowner.from_existing(custom_gen)
+    single_owner: Singleowner = Singleowner.from_existing(custom_gen)
 
     project_name = 'Generic_400_MWe'
     project_dir = Path(os.path.dirname(model.economics.MyPath), 'sam_economics', project_name)
@@ -152,15 +153,35 @@ def calculate_sam_economics(model: Model) -> SamEconomics:
     def sf(_v: float) -> float:
         return _sig_figs(_v, 5)
 
-    sam_economics: SamEconomics = SamEconomics(sam_cash_flow_profile=cash_flow)
+    sam_economics: SamEconomicsCalculations = SamEconomicsCalculations(sam_cash_flow_profile=cash_flow)
     sam_economics.lcoe_nominal.value = sf(single_owner.Outputs.lcoe_nom)
     sam_economics.project_irr.value = sf(single_owner.Outputs.project_return_aftertax_irr)
     sam_economics.project_npv.value = sf(single_owner.Outputs.project_return_aftertax_npv * 1e-6)
     sam_economics.capex.value = single_owner.Outputs.adjusted_installed_cost * 1e-6
 
+    sam_economics.wacc.value = _calculate_wacc(model, single_owner)
+
     return sam_economics
 
 
+def _calculate_wacc(model: Model, single_owner: Singleowner) -> float:
+    """
+    Calculation per SAM Help -> Financial Parameters -> Commercial -> Commercial Loan Parameters -> WACC
+    """
+
+    econ = model.economics
+    nominal_discount_rate = ((1 + econ.discountrate.value) * (1 + econ.RINFL.value) - 1) * 100
+    fed_tax_rate = max(single_owner.Outputs.cf_federal_tax_frac)
+    state_tax_rate = max(single_owner.Outputs.cf_state_tax_frac)
+    effective_tax_rate = (fed_tax_rate * (1 - state_tax_rate) + state_tax_rate) * 100
+    debt_fraction = single_owner.Outputs.debt_fraction / 100
+    wacc = (
+        nominal_discount_rate / 100 * (1 - debt_fraction)
+        + debt_fraction * econ.BIR.value * (1 - effective_tax_rate / 100)
+    ) * 100
+    return wacc
+
+
 def get_sam_cash_flow_profile_tabulated_output(model: Model, **tabulate_kw_args) -> str:
     """
     Note model must have already calculated economics for this to work (used in Outputs)
@@ -186,7 +207,7 @@ def get_entry_display(entry: Any) -> str:
                 return entry_display
         return entry
 
-    profile_display = model.economics.sam_economics.sam_cash_flow_profile.copy()
+    profile_display = model.economics.sam_economics_calculations.sam_cash_flow_profile.copy()
     for i in range(len(profile_display)):
         for j in range(len(profile_display[i])):
             profile_display[i][j] = get_entry_display(profile_display[i][j])

src/geophires_x/EconomicsUtils.py

@@ -1,3 +1,9 @@
+from __future__ import annotations
+
+from geophires_x.Parameter import OutputParameter
+from geophires_x.Units import Units, PercentUnit
+
+
 def BuildPricingModel(plantlifetime: int, StartPrice: float, EndPrice: float,
                       EscalationStartYear: int, EscalationRate: float, PTCAddition: list) -> list:
     """
@@ -29,3 +35,13 @@ def BuildPricingModel(plantlifetime: int, StartPrice: float, EndPrice: float,
             Price[i] = EndPrice
         Price[i] = Price[i] + PTCAddition[i]
     return Price
+
+
+def wacc_output_parameter() -> OutputParameter:
+    return OutputParameter(
+        Name='WACC',
+        ToolTipText='Weighted Average Cost of Capital',
+        UnitType=Units.PERCENT,
+        CurrentUnits=PercentUnit.PERCENT,
+        PreferredUnits=PercentUnit.PERCENT,
+    )

src/geophires_x/Outputs.py

@@ -254,8 +254,12 @@ def PrintOutputs(self, model: Model):
                 if model.economics.econmodel.value == EconomicModel.SAM_SINGLE_OWNER_PPA:
                     # TODO disambiguate interest rate for all economic models - see
                     #  https://github.com/softwareengineerprogrammer/GEOPHIRES/commit/535c02d4adbeeeca553b61e9b996fccf00016529
-                    irfl = Outputs._field_label(econ.interest_rate.Name, 49)
-                    f.write(f'      {irfl}{econ.interest_rate.value:10.2f} {econ.interest_rate.CurrentUnits.value}\n')
+                    ir_fl = Outputs._field_label(econ.interest_rate.Name, 49)
+                    f.write(f'      {ir_fl}{econ.interest_rate.value:10.2f} {econ.interest_rate.CurrentUnits.value}\n')
+
+                    wacc = econ.sam_economics_calculations.wacc
+                    wacc_fl = Outputs._field_label(wacc.Name, 49)
+                    f.write(f'      {wacc_fl}{wacc.value:10.2f} {wacc.CurrentUnits.value}\n')
 
                 # FIXME TODO unit is missing https://github.com/NREL/GEOPHIRES-X/issues/382
                 f.write(f'      Accrued financing during construction:            {model.economics.inflrateconstruction.value*100:10.2f} {model.economics.inflrateconstruction.CurrentUnits.value}\n')

src/geophires_x_client/geophires_x_result.py

@@ -67,6 +67,7 @@ class GeophiresXResult:
             'ECONOMIC PARAMETERS': [
                 _EqualSignDelimitedField('Economic Model'),
                 'Interest Rate',  # %
+                'WACC',
                 'Accrued financing during construction',
                 'Project lifetime',
                 'Capacity factor',

src/geophires_x_schema_generator/geophires-request.json

@@ -1154,7 +1154,7 @@
       "maximum": 1.0
     },
     "Utilization Factor": {
-      "description": "Ratio of the time the plant is running in normal production in a 1-year time period.",
+      "description": "Ratio of the time the plant is running in normal production in a 1-year time period. Synonymous with capacity factor.",
       "type": "number",
       "units": "",
       "category": "Surface Plant",
@@ -1577,7 +1577,7 @@
       "maximum": 1.0
     },
     "Discount Rate": {
-      "description": "Discount rate used in the Standard Levelized Cost Model. Discount Rate is synonymous with Fixed Internal Rate. If one is provided, the other's value will be automatically set to the same value.",
+      "description": "Discount rate used in the Standard Levelized Cost Model and SAM Economic Models. Discount Rate is synonymous with Fixed Internal Rate. If one is provided, the other's value will be automatically set to the same value.",
       "type": "number",
       "units": "",
       "category": "Economics",

src/geophires_x_schema_generator/geophires-result.json

@@ -14,7 +14,7 @@
         "Average Net Electricity Production": {},
         "Electricity breakeven price": {
           "type": "number",
-          "description": "LCOE",
+          "description": "LCOE. For SAM economic models, this is the nominal LCOE value (as opposed to real).",
           "units": "cents/kWh"
         },
         "Average Direct-Use Heat Production": {},
@@ -49,7 +49,7 @@
         "Segment 4   Geothermal gradient": {},
         "LCOE": {
           "type": "number",
-          "description": "LCOE",
+          "description": "LCOE. For SAM economic models, this is the nominal LCOE value (as opposed to real).",
           "units": "cents/kWh"
         },
         "LCOH": {
@@ -74,6 +74,11 @@
           "description": "",
           "units": "%"
         },
+        "WACC": {
+          "type": "number",
+          "description": "Weighted Average Cost of Capital",
+          "units": "%"
+        },
         "Accrued financing during construction": {},
         "Project lifetime": {},
         "Capacity factor": {},

tests/examples/example_SAM-single-owner-PPA.out

@@ -4,10 +4,10 @@
 
 Simulation Metadata
 ----------------------
- GEOPHIRES Version: 3.9.5
- Simulation Date: 2025-04-24
- Simulation Time:  09:38
- Calculation Time:      0.875 sec
+ GEOPHIRES Version: 3.9.6
+ Simulation Date: 2025-05-14
+ Simulation Time:  10:30
+ Calculation Time:      0.883 sec
 
                            ***SUMMARY OF RESULTS***
 
@@ -25,6 +25,7 @@ Simulation Metadata
 
       Economic Model = SAM Single Owner PPA
       Interest Rate:                                         7.00 %
+      WACC:                                                  6.41 %
       Accrued financing during construction:                  5.00
       Project lifetime:                                      20 yr
       Capacity factor:                                       90.0 %

tests/examples/example_SAM-single-owner-PPA.txt

@@ -15,7 +15,7 @@ Electricity Escalation Start Year, 1
 
 Fraction of Investment in Bonds, .5
 Inflated Bond Interest Rate, .05
-# Inflated Equity Interest Rate, .08, -- not supported by SAM economic model
+Discount Rate, 0.07
 
 Inflation Rate, .02
 Inflation Rate During Construction, 0.05