Update SAM-EM accrued financing during construction to account for construction years

Author: softwareengineerprogrammer

src/geophires_x/Economics.py

@@ -1966,6 +1966,14 @@ def __init__(self, model: Model):
             PreferredUnits=PercentUnit.PERCENT,
             CurrentUnits=PercentUnit.PERCENT
         )
+        self.accrued_financing_during_construction_percentage = self.OutputParameterDict[
+          self.accrued_financing_during_construction_percentage.Name] = OutputParameter(
+            Name='Accrued financing during construction',
+            UnitType=Units.PERCENT,
+            PreferredUnits=PercentUnit.PERCENT,
+            CurrentUnits=PercentUnit.PERCENT,
+            # TODO TooltipText
+        )
 
         self.after_tax_irr = self.OutputParameterDict[self.after_tax_irr.Name] = (
             after_tax_irr_parameter())
@@ -2328,6 +2336,12 @@ def _warn(_msg: str) -> None:
         self.sync_interest_rate(model)
         self.sync_well_drilling_and_completion_capital_cost_adjustment_factor(model)
 
+        # SAM Economic Models recalculate accrued financing value based on construction years.
+        # TODO to determine whether the same logic should be applied for other economic models.
+        self.accrued_financing_during_construction_percentage.value = self.inflrateconstruction.quantity().to(
+            convertible_unit(self.accrued_financing_during_construction_percentage.CurrentUnits)
+        ).magnitude
+
         model.logger.info(f'complete {__class__!s}: {sys._getframe().f_code.co_name}')
 
     def sync_interest_rate(self, model):

src/geophires_x/EconomicsSam.py

@@ -38,7 +38,7 @@
     project_vir_parameter,
     project_payback_period_parameter,
 )
-from geophires_x.GeoPHIRESUtils import is_float, is_int, sig_figs
+from geophires_x.GeoPHIRESUtils import is_float, is_int, sig_figs, quantity
 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
@@ -357,12 +357,18 @@ def _get_single_owner_parameters(model: Model) -> dict[str, Any]:
 
     itc = econ.RITCValue.quantity()
     total_capex = econ.CCap.quantity() + itc
-    ret['total_installed_cost'] = (
-        (total_capex * math.pow(1 + econ.inflrateconstruction.value, model.surfaceplant.construction_years.value))
-        .to('USD')
+
+    inflation_during_construction_factor = math.pow(
+        1 + econ.inflrateconstruction.value, model.surfaceplant.construction_years.value
+    )
+    econ.accrued_financing_during_construction_percentage.value = (
+        quantity(inflation_during_construction_factor - 1, 'dimensionless')
+        .to(convertible_unit(econ.accrued_financing_during_construction_percentage.CurrentUnits))
         .magnitude
     )
 
+    ret['total_installed_cost'] = (total_capex * inflation_during_construction_factor).to('USD').magnitude
+
     opex_musd = econ.Coam.value
     ret['om_fixed'] = [opex_musd * 1e6]
     # GEOPHIRES assumes O&M fixed costs are not affected by inflation

src/geophires_x/Outputs.py

@@ -268,7 +268,9 @@ def PrintOutputs(self, model: Model):
                         label = Outputs._field_label(field.Name, 49)
                         f.write(f'      {label}{field.value:10.2f} {field.CurrentUnits.value}\n')
 
-                f.write(f'      Accrued financing during construction:            {econ.inflrateconstruction.value:10.2f} {econ.inflrateconstruction.CurrentUnits.value}\n')
+                acf: OutputParameter = econ.accrued_financing_during_construction_percentage
+                acf_label = Outputs._field_label(acf.display_name, 49)
+                f.write(f'      {acf_label}{acf.value:10.2f} {acf.CurrentUnits.value}\n')
 
                 f.write(f'      Project lifetime:                              {model.surfaceplant.plant_lifetime.value:10.0f} {model.surfaceplant.plant_lifetime.CurrentUnits.value}\n')
                 f.write(f'      Capacity factor:                                 {model.surfaceplant.utilization_factor.value * 100:10.1f} %\n')

tests/examples/Fervo_Project_Cape-4.out

@@ -6,8 +6,8 @@ Simulation Metadata
 ----------------------
  GEOPHIRES Version: 3.9.40
  Simulation Date: 2025-07-26
- Simulation Time:  11:05
- Calculation Time:      1.723 sec
+ Simulation Time:  12:02
+ Calculation Time:      1.725 sec
 
                            ***SUMMARY OF RESULTS***
 
@@ -28,7 +28,7 @@ Simulation Metadata
       Real Discount Rate:                                   12.00 %
       Nominal Discount Rate:                                14.58 %
       WACC:                                                  8.30 %
-      Accrued financing during construction:                  4.77 %
+      Accrued financing during construction:                15.00 %
       Project lifetime:                                      30 yr
       Capacity factor:                                       90.0 %
       Project NPV:                                         641.24 MUSD