diff --git a/hems/fnn/fnn.go b/hems/fnn/fnn.go
index dd66667a9..8281382e8 100644
--- a/hems/fnn/fnn.go
+++ b/hems/fnn/fnn.go
@@ -23,14 +23,15 @@ func init() {
 // NewFromConfig creates an FNN HEMS from generic config.
 func NewFromConfig(ctx context.Context, other map[string]any, site site.API) (*Fnn, error) {
 	cc := struct {
-		MaxPower        float64 // TODO deprecated
-		MaxDimPower     float64
-		MaxCurtailPower float64
-		W3              *plugin.Config
-		S1              *plugin.Config
-		S2              *plugin.Config
-		W4              *plugin.Config
-		Interval        time.Duration
+		MaxPower             float64 // TODO deprecated
+		MaxDimPower          float64
+		MaxCurtailPower      float64 // TODO deprecated
+		ProductionNominalMax float64
+		W3                   *plugin.Config
+		S1                   *plugin.Config
+		S2                   *plugin.Config
+		W4                   *plugin.Config
+		Interval             time.Duration
 	}{
 		Interval: 10 * time.Second,
 	}
@@ -64,30 +65,34 @@ func NewFromConfig(ctx context.Context, other map[string]any, site site.API) (*F
 		return nil, err
 	}
 
-	maxCurtailPower := math.Abs(cc.MaxCurtailPower)
+	productionNominalMax := math.Abs(cc.MaxCurtailPower)
 	if cc.MaxPower > 0 {
-		maxCurtailPower = cc.MaxPower
+		productionNominalMax = cc.MaxPower
+	}
+	// ProductionNominalMax supersedes deprecated MaxCurtailPower/MaxPower
+	if cc.ProductionNominalMax > 0 {
+		productionNominalMax = math.Abs(cc.ProductionNominalMax)
 	}
 
-	return NewFnn(site, math.Abs(cc.MaxDimPower), maxCurtailPower, w3G, s1G, s2G, w4G, cc.Interval)
+	return NewFnn(site, math.Abs(cc.MaxDimPower), productionNominalMax, w3G, s1G, s2G, w4G, cc.Interval)
 }
 
-func NewFnn(site site.API, maxDimPower, maxCurtailPower float64, w3G, s1G, s2G, w4G func() (bool, error), interval time.Duration) (*Fnn, error) {
+func NewFnn(site site.API, maxDimPower, productionNominalMax float64, w3G, s1G, s2G, w4G func() (bool, error), interval time.Duration) (*Fnn, error) {
 	if w4G != nil && maxDimPower == 0 {
 		return nil, errors.New("cannot have w4 without power limit")
 	}
 
 	c := &Fnn{
-		log:               util.NewLogger("fnn"),
-		site:              site,
-		maxDimPower:       maxDimPower,
-		maxCurtailPower:   maxCurtailPower,
-		s1:                s1G,
-		s2:                s2G,
-		w3:                w3G,
-		w4:                w4G,
-		productionPercent: 100,
-		interval:          interval,
+		log:                  util.NewLogger("fnn"),
+		site:                 site,
+		maxDimPower:          maxDimPower,
+		productionNominalMax: productionNominalMax,
+		s1:                   s1G,
+		s2:                   s2G,
+		w3:                   w3G,
+		w4:                   w4G,
+		productionPercent:    100,
+		interval:             interval,
 	}
 
 	// read the relays once synchronously so limits are valid as soon as NewFnn returns
@@ -111,8 +116,8 @@ type Fnn struct {
 	w4          func() (bool, error)
 	publishFunc func()
 
-	maxDimPower     float64
-	maxCurtailPower float64
+	maxDimPower          float64
+	productionNominalMax float64
 
 	smartgridConsumptionID uint
 	smartgridProductionID  uint
@@ -211,7 +216,7 @@ func (c *Fnn) setProductionLimit(percent int) error {
 
 	limit := 0.0
 	if active {
-		limit = float64(percent) / 100 * c.maxCurtailPower
+		limit = float64(percent) / 100 * c.productionNominalMax
 	}
 
 	if err := smartgrid.UpdateSession(&c.smartgridProductionID, smartgrid.Curtail, c.site.GetGridPower(), limit, active); err != nil {
@@ -279,5 +284,5 @@ func (c *Fnn) MaxProductionPower() *float64 {
 		return new(0.0)
 	}
 
-	return new(float64(c.productionPercent) / 100 * c.maxCurtailPower)
+	return new(float64(c.productionPercent) / 100 * c.productionNominalMax)
 }
diff --git a/hems/fnn/fnn_config_test.go b/hems/fnn/fnn_config_test.go
new file mode 100644
index 000000000..aae58ddc7
--- /dev/null
+++ b/hems/fnn/fnn_config_test.go
@@ -0,0 +1,40 @@
+package fnn
+
+import (
+	"maps"
+	"testing"
+
+	"github.com/evcc-io/evcc/server/db"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// TestPowerParamFallback verifies productionnominalmax supersedes the
+// deprecated maxcurtailpower/maxpower params while both keep working.
+func TestPowerParamFallback(t *testing.T) {
+	require.NoError(t, db.NewInstance("sqlite", ":memory:"))
+
+	w3 := map[string]any{"source": "const", "value": "true"}
+
+	for _, tc := range []struct {
+		name string
+		conf map[string]any
+		want float64
+	}{
+		{"new param", map[string]any{"productionnominalmax": 5000.0}, 5000},
+		{"deprecated maxcurtailpower", map[string]any{"maxcurtailpower": 4000.0}, 4000},
+		{"deprecated maxpower", map[string]any{"maxpower": 3000.0}, 3000},
+		{"new supersedes deprecated", map[string]any{
+			"productionnominalmax": 5000.0, "maxcurtailpower": 4000.0, "maxpower": 3000.0,
+		}, 5000},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			conf := map[string]any{"w3": w3}
+			maps.Copy(conf, tc.conf)
+
+			fnn, err := NewFromConfig(t.Context(), conf, &stubSite{})
+			require.NoError(t, err)
+			assert.Equal(t, tc.want, fnn.productionNominalMax)
+		})
+	}
+}
diff --git a/templates/definition/hems/fnn-gpio.yaml b/templates/definition/hems/fnn-gpio.yaml
index a92448de3..a22103f5b 100644
--- a/templates/definition/hems/fnn-gpio.yaml
+++ b/templates/definition/hems/fnn-gpio.yaml
@@ -22,16 +22,17 @@ params:
     help:
       en: Input pin for the W4 signal (Dimmer for controllable loads)
       de: Eingangspin für das W4-Signal (Dimmen der steuerbaren Verbrauchseinrichtungen)
-  - name: maxproductionpower
+  - name: productionnominalmax
     type: float
     unit: W
-    required: true
     description:
       en: Installed generator power (Wp)
       de: Installierte Generatorleistung (Wp)
     help:
       en: Rated generator/module power (Wp) of the installation.
       de: Gesamtnennleistung bzw. Modul- oder Generatorleistung der Anlage (Bezugsgröße nach § 9 EEG).
+  - name: maxproductionpower
+    deprecated: true
   - name: w3pin
     type: int
     required: true
@@ -64,7 +65,7 @@ render: |
     source: gpio
     pin: {{ .w4pin }}
     function: read
-  maxcurtailpower: {{ .maxproductionpower }}
+  productionnominalmax: {{ or .productionnominalmax .maxproductionpower }}
   w3:
     source: gpio
     pin: {{ .w3pin }}
diff --git a/templates/definition/hems/hemspro-gpio.yaml b/templates/definition/hems/hemspro-gpio.yaml
index 93897afda..5e04c95ff 100644
--- a/templates/definition/hems/hemspro-gpio.yaml
+++ b/templates/definition/hems/hemspro-gpio.yaml
@@ -14,16 +14,17 @@ params:
     help:
       en: Power limit applied to the root circuit while the limit is active.
       de: Leistungsbegrenzung des Hauptstromkreises während die Limitierung aktiv ist.
-  - name: maxproductionpower
+  - name: productionnominalmax
     type: float
     unit: W
-    required: true
     description:
       en: Installed generator power (Wp)
       de: Installierte Generatorleistung (Wp)
     help:
       en: Rated generator/module power (Wp) of the installation.
       de: Gesamtnennleistung bzw. Modul- oder Generatorleistung der Anlage (Bezugsgröße nach § 9 EEG).
+  - name: maxproductionpower
+    deprecated: true
 render: |
   type: fnn
   maxdimpower: {{ .maxconsumptionpower }}
@@ -31,7 +32,7 @@ render: |
     source: gpio
     pin: 13
     function: read
-  maxcurtailpower: {{ .maxproductionpower }}
+  productionnominalmax: {{ or .productionnominalmax .maxproductionpower }}
   w3:
     source: gpio
     pin: 5