feat: add sell_price_equals_buy_price for net metering (NL saldering)

backend/api.py

@@ -3432,6 +3432,7 @@ async def setup_complete(payload: APISetupCompletePayload):
             "taxReduction": "tax_reduction",
             "spotMultiplier": "spot_multiplier",
             "exportSpotMultiplier": "export_spot_multiplier",
+            "sellPriceEqualsBuyPrice": "sell_price_equals_buy_price",
         }
         area = payload.area or payload.nordpoolArea
         if any(getattr(payload, f) is not None for f in _PRICE_MAP) or area:
@@ -3570,6 +3571,7 @@ def _nn(d: dict) -> dict:
                     "tax_reduction": payload.taxReduction,
                     "spot_multiplier": payload.spotMultiplier,
                     "export_spot_multiplier": payload.exportSpotMultiplier,
+                    "sell_price_equals_buy_price": payload.sellPriceEqualsBuyPrice,
                 }
             )
         if live_updates:

backend/api_conversion.py

@@ -96,6 +96,7 @@
         "tax_reduction",
         "spot_multiplier",
         "export_spot_multiplier",
+        "sell_price_equals_buy_price",
     }
 )
 

backend/api_dataclasses.py

@@ -1115,6 +1115,7 @@ class APISetupCompletePayload(BaseModel):
     taxReduction: float | None = None
     spotMultiplier: float | None = None
     exportSpotMultiplier: float | None = None
+    sellPriceEqualsBuyPrice: bool | None = None
     # Energy provider
     provider: str | None = None
     # Nordpool HACS entity (required when provider == "nordpool_hacs")

backend/settings_store.py

@@ -372,6 +372,7 @@ def _bootstrap_defaults() -> dict:
             HOUSE_VOLTAGE_V,
             MARKUP_RATE,
             SAFETY_MARGIN_FACTOR,
+            SELL_PRICE_EQUALS_BUY_PRICE,
             SPOT_MULTIPLIER,
             TAX_REDUCTION,
             USE_ACTUAL_PRICE,
@@ -406,6 +407,7 @@ def _bootstrap_defaults() -> dict:
                 "area": DEFAULT_AREA,
                 "spot_multiplier": SPOT_MULTIPLIER,
                 "export_spot_multiplier": EXPORT_SPOT_MULTIPLIER,
+                "sell_price_equals_buy_price": SELL_PRICE_EQUALS_BUY_PRICE,
                 "use_actual_price": USE_ACTUAL_PRICE,
             },
             "energy_provider": {
@@ -443,6 +445,7 @@ def _migrate_schema(self) -> None:
             BATTERY_EFFICIENCY_DISCHARGE,
             BATTERY_MIN_ACTION_PROFIT_THRESHOLD,
             EXPORT_SPOT_MULTIPLIER,
+            SELL_PRICE_EQUALS_BUY_PRICE,
             SPOT_MULTIPLIER,
             USE_ACTUAL_PRICE,
         )
@@ -522,6 +525,7 @@ def _migrate_schema(self) -> None:
             for key, default in (
                 ("spot_multiplier", SPOT_MULTIPLIER),
                 ("export_spot_multiplier", EXPORT_SPOT_MULTIPLIER),
+                ("sell_price_equals_buy_price", SELL_PRICE_EQUALS_BUY_PRICE),
                 ("use_actual_price", USE_ACTUAL_PRICE),
             ):
                 if key not in price:

backend/tests/test_settings_contracts.py

@@ -101,6 +101,7 @@ def _valid_options() -> dict:
             "tax_reduction": 0.2,
             "spot_multiplier": 1.0175,
             "export_spot_multiplier": 1.018,
+            "sell_price_equals_buy_price": False,
             "use_actual_price": False,
         },
     }

core/bess/battery_system_manager.py

@@ -164,6 +164,7 @@ def __init__(
             area=self.price_settings.area,
             spot_multiplier=self.price_settings.spot_multiplier,
             export_spot_multiplier=self.price_settings.export_spot_multiplier,
+            sell_price_equals_buy_price=self.price_settings.sell_price_equals_buy_price,
         )
 
         # Initialize monitors (created in start() if controller available)
@@ -3084,6 +3085,9 @@ def update_settings(self, settings: dict[str, Any]) -> None:
                 self._price_manager.export_spot_multiplier = (
                     self.price_settings.export_spot_multiplier
                 )
+                self._price_manager.sell_price_equals_buy_price = (
+                    self.price_settings.sell_price_equals_buy_price
+                )
                 self._price_manager.clear_cache()
 
             if "energy_provider" in settings:

core/bess/price_manager.py

@@ -391,6 +391,7 @@ def __init__(
         area: str,
         spot_multiplier: float = 1.0,
         export_spot_multiplier: float = 1.0,
+        sell_price_equals_buy_price: bool = False,
     ) -> None:
         """Initialize the price manager.
 
@@ -403,6 +404,8 @@ def __init__(
             area: Price area code (e.g. "SE4", "NO1", "DK1")
             spot_multiplier: Multiplicative factor on spot buy price (1.0 = no adjustment)
             export_spot_multiplier: Multiplicative factor on spot sell price
+            sell_price_equals_buy_price: Net metering (e.g. NL saldering) —
+                sell price is the full buy price instead of spot + compensation
         """
         self.price_source = price_source
         self.markup_rate = markup_rate
@@ -412,6 +415,7 @@ def __init__(
         self.area = area
         self.spot_multiplier = spot_multiplier
         self.export_spot_multiplier = export_spot_multiplier
+        self.sell_price_equals_buy_price = sell_price_equals_buy_price
         self._logger = logging.getLogger(__name__)
 
         # Cache for today's prices
@@ -456,6 +460,10 @@ def _calculate_sell_price(self, base_price: float) -> float:
         Returns:
             Calculated sell-back price
         """
+        if self.sell_price_equals_buy_price:
+            # Net metering (e.g. NL saldering): every exported kWh offsets an
+            # imported one on the bill, so its value is the full buy price.
+            return self._calculate_buy_price(base_price)
         return base_price * self.export_spot_multiplier + self.tax_reduction
 
     def get_price_data(self, target_date: date | None = None) -> list:

core/bess/settings.py

@@ -29,6 +29,7 @@
 )
 SPOT_MULTIPLIER = 1.0  # multiplicative factor on spot (1.0 = no adjustment)
 EXPORT_SPOT_MULTIPLIER = 1.0  # multiplicative factor on spot for sell price
+SELL_PRICE_EQUALS_BUY_PRICE = False  # net metering (e.g. NL saldering): sell = buy
 MIN_PROFIT = 0.2  # Minimum profit per kWh to consider a charge/discharge cycle
 USE_ACTUAL_PRICE = False  # Use raw Nordpool spot prices or include markup, VAT, etc.
 
@@ -95,6 +96,10 @@ class PriceSettings:
     tax_reduction: float = TAX_REDUCTION
     spot_multiplier: float = SPOT_MULTIPLIER
     export_spot_multiplier: float = EXPORT_SPOT_MULTIPLIER
+    # Net metering (e.g. NL "saldering", in force through 2026): exported
+    # energy offsets imported energy 1:1, so the effective sell price is the
+    # full buy price incl. markup, VAT and grid fees — not spot + compensation.
+    sell_price_equals_buy_price: bool = SELL_PRICE_EQUALS_BUY_PRICE
     min_profit: float = MIN_PROFIT
     use_actual_price: bool = USE_ACTUAL_PRICE
 

core/bess/tests/unit/test_price_manager.py

@@ -73,6 +73,41 @@ def test_spot_multiplier_defaults_to_no_adjustment():
     assert pm.sell_prices[0] == 1.0 + 0.2
 
 
+def test_sell_price_equals_buy_price_enabled():
+    """Net metering (NL saldering): sell price must equal the full buy price."""
+    mock_source = MockSource([1.0, 2.0])
+    pm = PriceManager(
+        price_source=mock_source,
+        markup_rate=0.02,
+        vat_multiplier=1.21,
+        additional_costs=0.0248,
+        tax_reduction=0.0248,
+        area="NL",
+        sell_price_equals_buy_price=True,
+    )
+
+    for base, buy, sell in zip([1.0, 2.0], pm.buy_prices, pm.sell_prices, strict=True):
+        assert buy == (base + 0.02) * 1.21 + 0.0248
+        assert sell == buy
+        # tax_reduction must play no role while net metering is on
+        assert sell != base + 0.0248
+
+
+def test_sell_price_equals_buy_price_defaults_off():
+    """Without the flag the sell price keeps the spot + compensation formula."""
+    mock_source = MockSource([1.0])
+    pm = PriceManager(
+        price_source=mock_source,
+        markup_rate=0.02,
+        vat_multiplier=1.21,
+        additional_costs=0.0248,
+        tax_reduction=0.0248,
+        area="NL",
+    )
+
+    assert pm.sell_prices[0] == 1.0 + 0.0248
+
+
 def test_controller_price_fetching():
     """Test price fetching from controller."""
     mock_controller = MagicMock()

frontend/src/components/settings/PricingFormSection.tsx

@@ -1,5 +1,5 @@
 import React from 'react';
-import { numField, txtInput, radioGroup, SectionCard } from './FormHelpers';
+import { numField, txtInput, radioGroup, toggle, SectionCard } from './FormHelpers';
 
 export interface PricingForm {
   currency: string;
@@ -18,6 +18,7 @@ export interface PricingForm {
   taxReduction: number;
   spotMultiplier: number;
   exportSpotMultiplier: number;
+  sellPriceEqualsBuyPrice: boolean;
 }
 
 interface Props {
@@ -36,7 +37,9 @@ export function PricingFormSection({ form, onChange }: Props) {
   const previewBuy = Number(
     ((previewSpot * sm + form.markupRate) * form.vatMultiplier + form.additionalCosts).toFixed(4),
   );
-  const previewSell = Number((previewSpot * esm + form.taxReduction).toFixed(4));
+  const previewSell = form.sellPriceEqualsBuyPrice
+    ? previewBuy
+    : Number((previewSpot * esm + form.taxReduction).toFixed(4));
 
   return (
     <div className="space-y-3">
@@ -116,6 +119,8 @@ export function PricingFormSection({ form, onChange }: Props) {
       >
         {!isOctopus && (
           <>
+            {toggle('Sell price equals buy price (net metering / saldering)', form.sellPriceEqualsBuyPrice,
+              v => onChange({ ...form, sellPriceEqualsBuyPrice: v }))}
             <div className="grid grid-cols-1 sm:grid-cols-2 gap-4">
               {isEntsoe && numField('Import Spot Multiplier', form.spotMultiplier,
                 v => onChange({ ...form, spotMultiplier: v }),
@@ -129,10 +134,10 @@ export function PricingFormSection({ form, onChange }: Props) {
               {numField('Additional Costs', form.additionalCosts,
                 v => onChange({ ...form, additionalCosts: v }),
                 { unit: `${currency}/kWh`, min: 0, step: 0.001 })}
-              {isEntsoe && numField('Export Spot Multiplier', form.exportSpotMultiplier,
+              {isEntsoe && !form.sellPriceEqualsBuyPrice && numField('Export Spot Multiplier', form.exportSpotMultiplier,
                 v => onChange({ ...form, exportSpotMultiplier: v }),
                 { unit: 'factor (1.0 = no adjustment)', min: 0.5, max: 2.0, step: 0.0001 })}
-              {numField('Export Compensation', form.taxReduction,
+              {!form.sellPriceEqualsBuyPrice && numField('Export Compensation', form.taxReduction,
                 v => onChange({ ...form, taxReduction: v }),
                 { unit: `${currency}/kWh`, min: 0, step: 0.001 })}
             </div>
@@ -149,7 +154,8 @@ export function PricingFormSection({ form, onChange }: Props) {
                 <div className="space-y-2 pt-2 border-t border-blue-200 dark:border-blue-700">
                   <p className="font-medium text-blue-900 dark:text-blue-200">How the raw spot price is converted:</p>
                   <p className="pl-2 border-l-2 border-blue-300 dark:border-blue-600"><strong>Buy price:</strong> (spot × import multiplier + markup) × VAT + additional costs</p>
-                  <p className="pl-2 border-l-2 border-blue-300 dark:border-blue-600"><strong>Sell price:</strong> spot × export multiplier + export compensation</p>
+                  <p className="pl-2 border-l-2 border-blue-300 dark:border-blue-600"><strong>Sell price:</strong> {form.sellPriceEqualsBuyPrice ? 'same as buy price (net metering)' : 'spot × export multiplier + export compensation'}</p>
+                  <div><span className="font-medium text-blue-900 dark:text-blue-200">Sell price equals buy price:</span> Enable under net metering ("saldering" in the Netherlands, in force through 2026): exported energy offsets imported energy 1:1 on your bill, so every exported kWh is worth the full buy price.</div>
                 </div>
               </div>
             ) : (
@@ -164,8 +170,9 @@ export function PricingFormSection({ form, onChange }: Props) {
                 <div className="space-y-2 pt-2 border-t border-blue-200 dark:border-blue-700">
                   <p className="font-medium text-blue-900 dark:text-blue-200">How the raw spot price is converted:</p>
                   <p className="pl-2 border-l-2 border-blue-300 dark:border-blue-600"><strong>Buy price:</strong> (raw spot + markup) × VAT multiplier + grid fees</p>
-                  <p className="pl-2 border-l-2 border-blue-300 dark:border-blue-600"><strong>Sell price:</strong> raw spot + export compensation</p>
+                  <p className="pl-2 border-l-2 border-blue-300 dark:border-blue-600"><strong>Sell price:</strong> {form.sellPriceEqualsBuyPrice ? 'same as buy price (net metering)' : 'raw spot + export compensation'}</p>
                   <p className="text-gray-500 dark:text-gray-500 italic">Note: Markup is added before VAT (ex-VAT), while grid fees already include VAT.</p>
+                  <div><span className="font-medium text-blue-900 dark:text-blue-200">Sell price equals buy price:</span> Enable under net metering ("saldering" in the Netherlands, in force through 2026): exported energy offsets imported energy 1:1 on your bill, so every exported kWh is worth the full buy price. E.g. Tibber NL.</div>
                 </div>
               </div>
             )}

frontend/src/pages/SettingsPage.tsx

@@ -55,6 +55,7 @@ const EMPTY_PRICING: PricingForm = {
   entsoeEntity: '',
   area: '', markupRate: 0, vatMultiplier: 1.25, additionalCosts: 0,
   taxReduction: 0, spotMultiplier: 1.0, exportSpotMultiplier: 1.0,
+  sellPriceEqualsBuyPrice: false,
 };
 const EMPTY_INVERTER: InverterForm = { inverterPlatform: 'growatt_server_min', deviceId: '', controlMode: 'tou' };
 
@@ -203,6 +204,7 @@ const SettingsPage: React.FC = () => {
         taxReduction: elec_s.taxReduction ?? 0,
         spotMultiplier: elec_s.spotMultiplier ?? 1.0,
         exportSpotMultiplier: elec_s.exportSpotMultiplier ?? 1.0,
+        sellPriceEqualsBuyPrice: elec_s.sellPriceEqualsBuyPrice ?? false,
       };
       setPricingForm(p);
       savedPricing.current = JSON.stringify(p);
@@ -408,6 +410,7 @@ const SettingsPage: React.FC = () => {
           taxReduction: pricingForm.taxReduction,
           spotMultiplier: pricingForm.spotMultiplier,
           exportSpotMultiplier: pricingForm.exportSpotMultiplier,
+          sellPriceEqualsBuyPrice: pricingForm.sellPriceEqualsBuyPrice,
           useActualPrice: false,
         },
         energyProvider: {

frontend/src/pages/SetupWizardPage.tsx

@@ -88,6 +88,7 @@ const SetupWizardPage: React.FC = () => {
     taxReduction: 0.2,
     spotMultiplier: 1.0,
     exportSpotMultiplier: 1.0,
+    sellPriceEqualsBuyPrice: false,
   });
 
   const handleScan = useCallback(async () => {
@@ -257,6 +258,7 @@ const SetupWizardPage: React.FC = () => {
         taxReduction:          elec.taxReduction                    ?? f.taxReduction,
         spotMultiplier:        elec.spotMultiplier                  ?? f.spotMultiplier,
         exportSpotMultiplier:  elec.exportSpotMultiplier            ?? f.exportSpotMultiplier,
+        sellPriceEqualsBuyPrice: elec.sellPriceEqualsBuyPrice       ?? f.sellPriceEqualsBuyPrice,
         // Restore saved config entry IDs so manual entries survive a wizard re-run
         nordpoolConfigEntryId: ep.nordpoolOfficial?.configEntryId ?? f.nordpoolConfigEntryId,
         nordpoolEntity:        ep.nordpoolHacs?.entity           ?? f.nordpoolEntity,
@@ -328,6 +330,7 @@ const SetupWizardPage: React.FC = () => {
         taxReduction: pricingForm.taxReduction,
         spotMultiplier: pricingForm.spotMultiplier,
         exportSpotMultiplier: pricingForm.exportSpotMultiplier,
+        sellPriceEqualsBuyPrice: pricingForm.sellPriceEqualsBuyPrice,
         // Nordpool HACS entity
         nordpoolEntity: pricingForm.nordpoolEntity || undefined,
         // Octopus Energy entity IDs

frontend/src/types.ts

@@ -129,6 +129,8 @@ export interface ElectricitySettings {
   vatMultiplier: number;
   additionalCosts: number;
   taxReduction: number;
+  // Net metering (e.g. NL saldering): sell price equals full buy price
+  sellPriceEqualsBuyPrice?: boolean;
   area: string;
 }