honor discount initial year cashflow in add-ons economics

Author: softwareengineerprogrammer

src/geophires_x/Economics.py

@@ -304,6 +304,22 @@ def CalculateCarbonRevenue(model, plant_lifetime: int, construction_years: int,
     return cash_flow_musd, cumm_cash_flow_musd, carbon_that_would_have_been_produced_annually_lbs, carbon_that_would_have_been_produced_total_lbs
 
 
+def calculate_npv(
+    discount_rate_tenths: float,
+    cashflow_series: list[float],
+    discount_initial_year_cashflow: bool
+) -> float:
+    # TODO warn/raise exception if discount rate > 1 (i.e. it's probably not converted from percent to tenths)
+
+    npv_cashflow_series = cashflow_series.copy()  # Copy to guard against unintentional mutation of consumer field
+
+    if discount_initial_year_cashflow:
+        # Enable Excel-style NPV calculation - see https://github.com/NREL/GEOPHIRES-X/discussions/344
+        npv_cashflow_series = [0, *npv_cashflow_series]
+
+    return npf.npv(discount_rate_tenths, npv_cashflow_series)
+
+
 def CalculateFinancialPerformance(plantlifetime: int,
                                   FixedInternalRate: float,
                                   TotalRevenue: list,
@@ -341,13 +357,8 @@ def CalculateFinancialPerformance(plantlifetime: int,
     """
     # Calculate financial performance values using numpy financials
 
-    cashflow_series = TotalRevenue.copy()
-
-    if discount_initial_year_cashflow:
-        cashflow_series = [0, *cashflow_series]
-
-    NPV = npf.npv(FixedInternalRate / 100, cashflow_series)
-    IRR = npf.irr(cashflow_series)
+    NPV = calculate_npv(FixedInternalRate / 100, TotalRevenue.copy(), discount_initial_year_cashflow)
+    IRR = npf.irr(TotalRevenue)
     if math.isnan(IRR):
         IRR = 0.0
     else:

src/geophires_x/EconomicsAddOns.py

@@ -347,7 +347,12 @@ def Calculate(self, model: Model) -> None:
 
         # Now calculate a new "NPV", "IRR", "VIR", "Payback Period", and "MOIC"
         # Calculate more financial values using numpy financials
-        self.ProjectNPV.value = npf.npv(self.FixedInternalRate.value / 100, self.ProjectCashFlow.value)
+        self.ProjectNPV.value = Economics.calculate_npv(
+            self.FixedInternalRate.value / 100,
+            self.ProjectCashFlow.value.copy(),
+            self.discount_initial_year_cashflow.value
+        )
+
         self.ProjectIRR.value = npf.irr(self.ProjectCashFlow.value)
         if math.isnan(self.ProjectIRR.value):
             self.ProjectIRR.value = 0.0

src/geophires_x/OutputsAddOns.py

@@ -41,7 +41,7 @@ def PrintOutputs(self, model) -> tuple:
                 addon_results.append(OutputTableItem('Adjusted Project CAPEX (after incentives, grants, AddOns, etc)', '{0:10.2f}'.format(model.addeconomics.AdjustedProjectCAPEX.value), model.addeconomics.AdjustedProjectCAPEX.PreferredUnits.value))
                 f.write(f"      Adjusted Project OPEX (after incentives, grants, AddOns, etc):    {model.addeconomics.AdjustedProjectOPEX.value:10.2f} " + model.addeconomics.AdjustedProjectOPEX.PreferredUnits.value + NL)
                 addon_results.append(OutputTableItem('Adjusted Project OPEX (after incentives, grants, AddOns, etc)', '{0:10.2f}'.format(model.addeconomics.AdjustedProjectOPEX.value), model.addeconomics.AdjustedProjectOPEX.PreferredUnits.value))
-                f.write(f"      Project NPV   (including AddOns):                                 {model.addeconomics.ProjectNPV.value:10.2f} " + model.addeconomics.ProjectNPV.PreferredUnits.value + NL)
+                f.write(f'      Project NPV   (including AddOns):                                 {model.addeconomics.ProjectNPV.value:10.2f} {model.addeconomics.ProjectNPV.PreferredUnits.value}\n')
                 addon_results.append(OutputTableItem('Project NPV (including AddOns)', '{0:10.2f}'.format(model.addeconomics.ProjectNPV.value), model.addeconomics.ProjectNPV.PreferredUnits.value))
                 f.write(f"      Project IRR   (including AddOns):                                 {model.addeconomics.ProjectIRR.value:10.2f} " + model.addeconomics.ProjectIRR.PreferredUnits.value + NL)
                 addon_results.append(OutputTableItem('Project IRR (including AddOns)', '{0:10.2f}'.format(model.addeconomics.ProjectIRR.value), model.addeconomics.ProjectIRR.PreferredUnits.value))