From e702924fe39effc91a544a506e764b782a04df05 Mon Sep 17 00:00:00 2001
From: andig <andi@evcc.io>
Date: Mon, 29 Dec 2025 17:29:27 +0100
Subject: [PATCH] =?UTF-8?q?Add=20EEG=20=C2=A79=20curtailment=20api=20(#258?=
 =?UTF-8?q?87)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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---
 api/api.go              | 14 ++++++++++++--
 api/mock.go             | 26 ++++++++++++++++++++++++++
 core/circuit/circuit.go | 28 +++++++++++++++++++++++++---
 core/site_circuits.go   |  2 ++
 4 files changed, 65 insertions(+), 5 deletions(-)

diff --git a/api/api.go b/api/api.go
index 34c212717..cb3680ac1 100644
--- a/api/api.go
+++ b/api/api.go
@@ -192,12 +192,18 @@ type SocLimiter interface {
 	GetLimitSoc() (int64, error)
 }
 
-// Dimmer provides §14a dimming
+// Dimmer provides EnWG §14a dimming
 type Dimmer interface {
 	Dimmed() (bool, error)
 	Dim(bool) error
 }
 
+// Curtailer provides EEG §9 curtailment
+type Curtailer interface {
+	Curtailed() (bool, error)
+	Curtail(bool) error
+}
+
 // ChargeController allows to start/stop the charging session on the vehicle side
 type ChargeController interface {
 	ChargeEnable(bool) error
@@ -272,9 +278,13 @@ type Circuit interface {
 	ValidateCurrent(old, new float64) float64
 	ValidatePower(old, new float64) float64
 
-	// §14a
+	// EnWG §14a - reduce demand/consumption
 	Dim(bool)
 	Dimmed() bool
+
+	// EEG §9 - reduce feed-in to the grid
+	Curtail(bool)
+	Curtailed() bool
 }
 
 // Redactor is an interface to redact sensitive data
diff --git a/api/mock.go b/api/mock.go
index d009b80a7..4591c1e38 100644
--- a/api/mock.go
+++ b/api/mock.go
@@ -856,6 +856,32 @@ func (m *MockCircuit) EXPECT() *MockCircuitMockRecorder {
 	return m.recorder
 }
 
+// Curtail mocks base method.
+func (m *MockCircuit) Curtail(arg0 bool) {
+	m.ctrl.T.Helper()
+	m.ctrl.Call(m, "Curtail", arg0)
+}
+
+// Curtail indicates an expected call of Curtail.
+func (mr *MockCircuitMockRecorder) Curtail(arg0 any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Curtail", reflect.TypeOf((*MockCircuit)(nil).Curtail), arg0)
+}
+
+// Curtailed mocks base method.
+func (m *MockCircuit) Curtailed() bool {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "Curtailed")
+	ret0, _ := ret[0].(bool)
+	return ret0
+}
+
+// Curtailed indicates an expected call of Curtailed.
+func (mr *MockCircuitMockRecorder) Curtailed() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Curtailed", reflect.TypeOf((*MockCircuit)(nil).Curtailed))
+}
+
 // Dim mocks base method.
 func (m *MockCircuit) Dim(arg0 bool) {
 	m.ctrl.T.Helper()
diff --git a/core/circuit/circuit.go b/core/circuit/circuit.go
index b40e7875d..97729daf0 100644
--- a/core/circuit/circuit.go
+++ b/core/circuit/circuit.go
@@ -34,9 +34,10 @@ type Circuit struct {
 	getMaxCurrent func() (float64, error) // dynamic max allowed current
 	getMaxPower   func() (float64, error) // dynamic max allowed power
 
-	current float64
-	power   float64
-	dimmed  bool
+	current   float64
+	power     float64
+	dimmed    bool
+	curtailed bool
 
 	currentUpdated time.Time
 	powerUpdated   time.Time
@@ -402,3 +403,24 @@ func (c *Circuit) Dimmed() bool {
 
 	return c.parent.Dimmed()
 }
+
+func (c *Circuit) Curtail(curtail bool) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.curtailed = curtail
+}
+
+func (c *Circuit) Curtailed() bool {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+
+	if c.curtailed {
+		return true
+	}
+
+	if c.parent == nil {
+		return false
+	}
+
+	return c.parent.Curtailed()
+}
diff --git a/core/site_circuits.go b/core/site_circuits.go
index ee0e2b6f5..319348e13 100644
--- a/core/site_circuits.go
+++ b/core/site_circuits.go
@@ -19,6 +19,7 @@ type circuitStruct struct {
 	MaxPower   float64  `json:"maxPower,omitempty"`
 	MaxCurrent float64  `json:"maxCurrent,omitempty"`
 	Dimmed     bool     `json:"dimmed"`
+	Curtailed  bool     `json:"curtailed"`
 }
 
 // publishCircuits returns a list of circuit titles
@@ -37,6 +38,7 @@ func (site *Site) publishCircuits() {
 			MaxPower:   instance.GetMaxPower(),
 			MaxCurrent: instance.GetMaxCurrent(),
 			Dimmed:     instance.Dimmed(),
+			Curtailed:  instance.Curtailed(),
 		}
 
 		if instance.GetMaxCurrent() > 0 {