From 04c2f8c1ac6a53fbb04012f103ef7566ddef1fec Mon Sep 17 00:00:00 2001
From: andig <andi@evcc.io>
Date: Sun, 26 Oct 2025 17:08:58 +0100
Subject: [PATCH] Vaillant: add support for multiple systems per account
 (#24718)

---
 charger/helper.go                          | 21 +++++++++++++++------
 charger/vaillant.go                        |  9 +++++++--
 templates/definition/charger/vaillant.yaml | 10 ++++++++++
 3 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/charger/helper.go b/charger/helper.go
index 214ad8194..341c04c50 100644
--- a/charger/helper.go
+++ b/charger/helper.go
@@ -27,16 +27,25 @@ func ensureChargerEx[T any](
 	id string,
 	list func() ([]T, error),
 	extract func(T) (string, error),
+) (T, error) {
+	return ensureEx("charger", id, list, extract)
+}
+
+// ensureEx extracts element with name typ with matching id from list of elements
+func ensureEx[T any](
+	typ, id string,
+	list func() ([]T, error),
+	extract func(T) (string, error),
 ) (T, error) {
 	var zero T
 
-	chargers, err := list()
+	elems, err := list()
 	if err != nil {
-		return zero, fmt.Errorf("cannot get chargers: %w", err)
+		return zero, fmt.Errorf("cannot get %ss: %w", typ, err)
 	}
 
 	if id = strings.ToUpper(id); id != "" {
-		for _, charger := range chargers {
+		for _, charger := range elems {
 			cc, err := extract(charger)
 			if err != nil {
 				return zero, err
@@ -45,12 +54,12 @@ func ensureChargerEx[T any](
 				return charger, nil
 			}
 		}
-	} else if len(chargers) == 1 {
+	} else if len(elems) == 1 {
 		// id empty and exactly one charger
-		return chargers[0], nil
+		return elems[0], nil
 	}
 
-	return zero, fmt.Errorf("cannot find charger, got: %v", lo.Map(chargers, func(v T, _ int) string {
+	return zero, fmt.Errorf("cannot find %s, got: %v", typ, lo.Map(elems, func(v T, _ int) string {
 		vin, _ := extract(v)
 		return vin
 	}))
diff --git a/charger/vaillant.go b/charger/vaillant.go
index 0790f5c6f..12f53a1bd 100644
--- a/charger/vaillant.go
+++ b/charger/vaillant.go
@@ -51,6 +51,7 @@ func NewVaillantFromConfig(ctx context.Context, other map[string]interface{}) (a
 		embed           `mapstructure:",squash"`
 		User, Password  string
 		Realm           string
+		System          string
 		HeatingZone     int
 		HeatingSetpoint float32
 		Cache           time.Duration
@@ -85,12 +86,16 @@ func NewVaillantFromConfig(ctx context.Context, other map[string]interface{}) (a
 		return nil, err
 	}
 
-	homes, err := conn.GetHomes()
+	home, err := ensureEx("home", cc.System, func() ([]sensonet.Home, error) {
+		return conn.GetHomes()
+	}, func(home sensonet.Home) (string, error) {
+		return home.SystemID, nil
+	})
 	if err != nil {
 		return nil, err
 	}
 
-	systemId := homes[0].SystemID
+	systemId := home.SystemID
 	heating := cc.HeatingSetpoint > 0
 
 	wwCancel := func() {}
diff --git a/templates/definition/charger/vaillant.yaml b/templates/definition/charger/vaillant.yaml
index 0d792eec4..d114353cc 100644
--- a/templates/definition/charger/vaillant.yaml
+++ b/templates/definition/charger/vaillant.yaml
@@ -29,6 +29,13 @@ params:
     description:
       de: Boost Temperatur
       en: Boost temperature
+  - name: system
+    description:
+      de: Name der Anlage
+      en: Name of the system
+    help:
+      de: Notwendig falls mehrere Anlagen im Account vorhanden sind
+      en: Required if multiple systems are present in the account
   - name: phases
     deprecated: true
 render: |
@@ -36,5 +43,8 @@ render: |
   user: {{ .user }}
   password: {{ .password }}
   realm: {{ if eq .realm "AT" -}} vaillant-austria-b2c {{- end }}
+  {{- if .system }}
+  system: {{ .system }}
+  {{- end }}
   heatingzone: {{ .zone }}
   heatingsetpoint: {{ .setpoint }}