diff --git a/cmd/flags.go b/cmd/flags.go
index 58273a335..3d56024b3 100644
--- a/cmd/flags.go
+++ b/cmd/flags.go
@@ -1,6 +1,10 @@
 package cmd
 
 import (
+	"strings"
+
+	"github.com/evcc-io/evcc/util/templates"
+	"github.com/samber/lo"
 	"github.com/spf13/cobra"
 )
 
@@ -11,6 +15,10 @@ const (
 	flagIgnoreDatabase            = "ignore-db"
 	flagIgnoreDatabaseDescription = "Run command ignoring service database"
 
+	flagTemplate            = "template"
+	flagTemplateDescription = "Add custom template (useful for debugging)"
+	flagTemplateType        = "template-type"
+
 	flagDisableAuth            = "disable-auth"
 	flagDisableAuthDescription = "Disable authentication (dangerous)"
 
@@ -54,6 +62,11 @@ const (
 	flagForce  = "force"
 )
 
+var flagTemplateTypeDescription = "Custom template type (" + strings.Join(
+	lo.Map([]templates.Class{templates.Charger, templates.Meter, templates.Tariff, templates.Vehicle}, func(t templates.Class, _ int) string {
+		return t.String()
+	}), ", ") + ")"
+
 func bind(cmd *cobra.Command, key string, flagName ...string) {
 	name := key
 	if len(flagName) == 1 {
diff --git a/cmd/root.go b/cmd/root.go
index 83e27c6df..aef0c5da2 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -69,6 +69,8 @@ func init() {
 	rootCmd.PersistentFlags().BoolP("help", "h", false, "Help")
 	rootCmd.PersistentFlags().Bool(flagHeaders, false, flagHeadersDescription)
 	rootCmd.PersistentFlags().Bool(flagIgnoreDatabase, false, flagIgnoreDatabaseDescription)
+	rootCmd.PersistentFlags().String(flagTemplate, "", flagTemplateDescription)
+	rootCmd.PersistentFlags().String(flagTemplateType, "", flagTemplateTypeDescription)
 
 	// config file options
 	rootCmd.PersistentFlags().StringP("log", "l", "info", "Log level (fatal, error, warn, info, debug, trace)")
diff --git a/cmd/setup.go b/cmd/setup.go
index d44db535a..1a7928a65 100644
--- a/cmd/setup.go
+++ b/cmd/setup.go
@@ -467,14 +467,28 @@ func configureSponsorship(token string) (err error) {
 	return sponsor.ConfigureSponsorship(token)
 }
 
-func configureEnvironment(cmd *cobra.Command, conf *globalconfig.All) (err error) {
+func configureEnvironment(cmd *cobra.Command, conf *globalconfig.All) error {
 	// full http request log
 	if cmd.Flag(flagHeaders).Changed {
 		request.LogHeaders = true
 	}
 
 	// setup persistence
-	err = wrapErrorWithClass(ClassDatabase, configureDatabase(conf.Database))
+	err := wrapErrorWithClass(ClassDatabase, configureDatabase(conf.Database))
+
+	// setup additional templates
+	if err == nil {
+		if cmd.PersistentFlags().Changed(flagTemplate) {
+			class, err := templates.ClassString(cmd.PersistentFlags().Lookup(flagTemplateType).Value.String())
+			if err != nil {
+				return err
+			}
+
+			if err := templates.Register(class, cmd.Flag(flagTemplate).Value.String()); err != nil {
+				return err
+			}
+		}
+	}
 
 	// setup translations
 	if err == nil {
@@ -519,7 +533,7 @@ func configureEnvironment(cmd *cobra.Command, conf *globalconfig.All) (err error
 		err = config.Init(db.Instance)
 	}
 
-	return
+	return err
 }
 
 // configureDatabase configures session database
diff --git a/util/templates/init.go b/util/templates/init.go
index d34675835..9b88f6a12 100644
--- a/util/templates/init.go
+++ b/util/templates/init.go
@@ -5,6 +5,7 @@ import (
 	"embed"
 	"fmt"
 	"io/fs"
+	"os"
 	"slices"
 	"sync"
 	"text/template"
@@ -37,7 +38,27 @@ func init() {
 	}
 }
 
-func FromBytes(b []byte) (Template, error) {
+func Register(class Class, filepath string) error {
+	b, err := os.ReadFile(filepath)
+	if err != nil {
+		return err
+	}
+
+	tmpl, err := fromBytes(b)
+	if err != nil {
+		return fmt.Errorf("processing template '%s' failed: %w", filepath, err)
+	}
+
+	if slices.ContainsFunc(templates[class], func(t Template) bool { return t.Template == tmpl.Template }) {
+		return fmt.Errorf("duplicate template name '%s' found in file '%s'", tmpl.Template, filepath)
+	}
+
+	templates[class] = append(templates[class], tmpl)
+
+	return nil
+}
+
+func fromBytes(b []byte) (Template, error) {
 	// panic if template definition contains unknown fields
 	dec := yaml.NewDecoder(bytes.NewReader(b))
 	dec.KnownFields(true)
@@ -79,7 +100,7 @@ func load(class Class) (res []Template) {
 			return err
 		}
 
-		tmpl, err := FromBytes(b)
+		tmpl, err := fromBytes(b)
 		if err != nil {
 			return fmt.Errorf("processing template '%s' failed: %w", filepath, err)
 		}