From 3626b7f658cf60533b29e0ed147e2f7c20da6903 Mon Sep 17 00:00:00 2001
From: RenatusRo <126881912+RenatusRo@users.noreply.github.com>
Date: Fri, 27 Feb 2026 08:55:24 +0100
Subject: [PATCH] Optimizer: add battery grid charging (#27696)

---
 core/site_optimizer.go | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/core/site_optimizer.go b/core/site_optimizer.go
index 1f1b1ed6d..a21052921 100644
--- a/core/site_optimizer.go
+++ b/core/site_optimizer.go
@@ -205,7 +205,7 @@ func (site *Site) optimizerUpdate(battery []types.Measurement) error {
 			continue
 		}
 
-		add(site.batteryRequest(dev, b))
+		add(site.batteryRequest(dev, b, grid, minLen, firstSlotDuration))
 	}
 
 	httpClient := request.NewClient(site.log)
@@ -398,7 +398,7 @@ func (site *Site) loadpointRequest(lp loadpoint.API, minLen int, firstSlotDurati
 	return bat, detail
 }
 
-func (site *Site) batteryRequest(dev config.Device[api.Meter], b types.Measurement) (evopt.BatteryConfig, batteryDetail) {
+func (site *Site) batteryRequest(dev config.Device[api.Meter], b types.Measurement, grid api.Rates, minLen int, firstSlotDuration time.Duration) (evopt.BatteryConfig, batteryDetail) {
 	bat := evopt.BatteryConfig{
 		CMax:     batteryPower,
 		DMax:     batteryPower,
@@ -432,6 +432,13 @@ func (site *Site) batteryRequest(dev config.Device[api.Meter], b types.Measureme
 		Capacity: *b.Capacity,
 	}
 
+	// tariff forecast-based grid charging demand
+	if bat.ChargeFromGrid {
+		if demand := site.applyBatteryGridChargeLimit(bat.CMax, grid, minLen); demand != nil {
+			bat.PDemand = prorate(demand, firstSlotDuration)
+		}
+	}
+
 	return bat, detail
 }
 
@@ -678,6 +685,30 @@ func applySmartCostLimit(lp loadpoint.API, demand []float32, grid api.Rates, min
 	return demand
 }
 
+func (site *Site) applyBatteryGridChargeLimit(cMax float32, grid api.Rates, minLen int) []float32 {
+	limit := site.GetBatteryGridChargeLimit()
+	if limit == nil {
+		return nil
+	}
+
+	maxLen := min(minLen, len(grid))
+
+	if hasAffordableSlots := slices.ContainsFunc(grid[:maxLen], func(r api.Rate) bool {
+		return r.Value <= *limit
+	}); !hasAffordableSlots {
+		return nil
+	}
+
+	demand := make([]float32, minLen)
+	for i := range maxLen {
+		if grid[i].Value <= *limit {
+			demand[i] = float32(float64(cMax) / slotsPerHour)
+		}
+	}
+
+	return demand
+}
+
 // apiError extracts error message from optimizer API response
 func apiError(resp *evopt.PostOptimizeChargeScheduleResponse) error {
 	var errObj *evopt.Error