diff --git a/meter/zendure/connection.go b/meter/zendure/connection.go
index da8194699..f1c7de9fe 100644
--- a/meter/zendure/connection.go
+++ b/meter/zendure/connection.go
@@ -73,12 +73,10 @@ func (c *Connection) handler(data string) {
 	}
 
 	c.data.SetFunc(func(v Data) Data {
-		if err := mergo.Merge(&v, res.Data); err != nil {
+		if err := mergo.Merge(&v, res.Data, mergo.WithOverride); err != nil {
 			c.log.ERROR.Println(err)
 		}
 
-		c.log.TRACE.Printf("!! data: %+v", v)
-
 		return v
 	})
 }
diff --git a/meter/zendure/connection_test.go b/meter/zendure/connection_test.go
new file mode 100644
index 000000000..12eb9bfb2
--- /dev/null
+++ b/meter/zendure/connection_test.go
@@ -0,0 +1,31 @@
+package zendure
+
+import (
+	"testing"
+	"time"
+
+	"github.com/evcc-io/evcc/util"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestHandler(t *testing.T) {
+	conn := &Connection{
+		log:  util.NewLogger("test"),
+		data: util.NewMonitor[Data](time.Minute),
+	}
+
+	{
+		conn.handler(`{"solarInputPower":113,"sn":"serial"}`)
+		res, err := conn.data.Get()
+		assert.NoError(t, err)
+
+		assert.Equal(t, Data{SolarInputPower: 113, Sn: "serial"}, res)
+	}
+	{
+		conn.handler(`{"solarInputPower":125,"sn":"serial"}`)
+		res, err := conn.data.Get()
+		assert.NoError(t, err)
+
+		assert.Equal(t, Data{SolarInputPower: 125, Sn: "serial"}, res)
+	}
+}