diff --git a/CHANGELOG.md b/CHANGELOG.md
index 31864b97a7..363185c181 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -245,6 +245,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Cleanups and log capturing in `ExtEvDataServiceSpec` [#1320](https://github.com/ie3-institute/simona/issues/1320)
 - Fix tolerance in `ThermalGridIT` [#1345](https://github.com/ie3-institute/simona/issues/1345)
 - Fix startingState of `ThermalHouse` and `ThermalStorage` [#1347](https://github.com/ie3-institute/simona/issues/1347)
+- Fix default config values not written to output config file [#1355](https://github.com/ie3-institute/simona/issues/1355)
 
 ### Removed
 - Removed `SimonaListerner` and related code [#1205](https://github.com/ie3-institute/simona/issues/1205)
diff --git a/src/main/scala/edu/ie3/simona/config/SimonaConfig.scala b/src/main/scala/edu/ie3/simona/config/SimonaConfig.scala
index c691114747..b780b949de 100644
--- a/src/main/scala/edu/ie3/simona/config/SimonaConfig.scala
+++ b/src/main/scala/edu/ie3/simona/config/SimonaConfig.scala
@@ -6,7 +6,8 @@
 
 package edu.ie3.simona.config
 
-import com.typesafe.config.Config
+import com.typesafe.config.{Config, ConfigValue}
+import edu.ie3.simona.config.SimonaConfig.writer
 import edu.ie3.simona.exceptions.CriticalFailureException
 import pureconfig._
 import pureconfig.error._
@@ -18,13 +19,22 @@ import scala.language.implicitConversions
 
 final case class SimonaConfig(
     simona: SimonaConfig.Simona
-)
+) {
+
+  /** Returns the default config values.
+    */
+  def defaults: ConfigValue = writer.to(this)
+}
 
 object SimonaConfig {
   // pure config start
   implicit def productHint[T]: ProductHint[T] =
     ProductHint[T](ConfigFieldMapping(CamelCase, CamelCase))
 
+  /** Returns a writer for [[SimonaConfig]].
+    */
+  private def writer: ConfigWriter[SimonaConfig] = ConfigWriter[SimonaConfig]
+
   def apply(typeSafeConfig: Config): SimonaConfig =
     apply(ConfigSource.fromConfig(typeSafeConfig))
 
diff --git a/src/main/scala/edu/ie3/simona/util/ResultFileHierarchy.scala b/src/main/scala/edu/ie3/simona/util/ResultFileHierarchy.scala
index 13dc92ce9b..4e99274973 100644
--- a/src/main/scala/edu/ie3/simona/util/ResultFileHierarchy.scala
+++ b/src/main/scala/edu/ie3/simona/util/ResultFileHierarchy.scala
@@ -237,6 +237,7 @@ object ResultFileHierarchy extends LazyLogging {
       bw.write(
         config
           .root()
+          .withFallback(simonaConfig.defaults)
           .render(
             ConfigRenderOptions
               .defaults()