From 37e565993624e6938f9abc36ba02e97a4af43ae6 Mon Sep 17 00:00:00 2001
From: andig <andi@evcc.io>
Date: Sat, 9 May 2026 14:43:26 +0200
Subject: [PATCH] Batteries: track energy metrics (#29780)

---
 core/site.go | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/core/site.go b/core/site.go
index b5904f887..8f3c39d14 100644
--- a/core/site.go
+++ b/core/site.go
@@ -88,6 +88,7 @@ type Site struct {
 	pvEnergy    map[string]*metrics.Accumulator
 
 	homeEnergy, gridEnergy *metrics.Collector
+	batteryEnergy          map[string]*metrics.Collector // per-battery, keyed by meter ref
 
 	// cached state
 	gridPower                float64            // Grid power
@@ -216,6 +217,12 @@ func (site *Site) Boot(log *util.Logger, loadpoints []*Loadpoint, tariffs *tarif
 			return err
 		}
 		site.batteryMeters = append(site.batteryMeters, dev)
+
+		me, err := metrics.NewCollector(metrics.Battery, ref)
+		if err != nil {
+			return err
+		}
+		site.batteryEnergy[ref] = me
 	}
 
 	// meters used only for monitoring
@@ -251,10 +258,11 @@ func (site *Site) Boot(log *util.Logger, loadpoints []*Loadpoint, tariffs *tarif
 // NewSite creates a Site with sane defaults
 func NewSite() *Site {
 	site := &Site{
-		log:        util.NewLogger("site"),
-		Voltage:    230, // V
-		pvEnergy:   make(map[string]*metrics.Accumulator),
-		fcstEnergy: metrics.NewAccumulator(),
+		log:           util.NewLogger("site"),
+		Voltage:       230, // V
+		pvEnergy:      make(map[string]*metrics.Accumulator),
+		batteryEnergy: make(map[string]*metrics.Collector),
+		fcstEnergy:    metrics.NewAccumulator(),
 	}
 
 	return site
@@ -671,6 +679,22 @@ func (site *Site) updateBatteryMeters() {
 
 	site.battery.Devices = mm
 
+	// accumulate per-battery energy (charging = import, discharging = export — from battery POV toward grid root)
+	for i, dev := range site.batteryMeters {
+		ref := dev.Config().Name
+		c, ok := site.batteryEnergy[ref]
+		if !ok {
+			continue
+		}
+		var exportEnergy *float64
+		if mm[i].Energy > 0 {
+			exportEnergy = &mm[i].Energy
+		}
+		if err := c.AddEnergy(nil, exportEnergy, -mm[i].Power); err != nil {
+			site.log.ERROR.Printf("persist battery %d energy: %v", i+1, err)
+		}
+	}
+
 	site.publish(keys.Battery, site.battery)
 }