diff --git a/doc/release_notes.rst b/doc/release_notes.rst
index 75eb345e4..5b14eebd4 100644
--- a/doc/release_notes.rst
+++ b/doc/release_notes.rst
@@ -86,6 +86,8 @@ Upcoming Release
 
 * Fix GADM naming bug related to level-2 clustering `PR #684 <https://github.com/pypsa-meets-earth/pypsa-earth/pull/684>`__
 
+* Fix append bug in build_powerplants rule `PR #686 <https://github.com/pypsa-meets-earth/pypsa-earth/pull/686>`__
+
 PyPSA-Earth 0.1.0
 =================
 
diff --git a/scripts/build_powerplants.py b/scripts/build_powerplants.py
index cb52e7abb..b374d87bf 100644
--- a/scripts/build_powerplants.py
+++ b/scripts/build_powerplants.py
@@ -247,7 +247,9 @@ def add_custom_powerplants(ppl, inputs, config):
     # if isinstance(custom_ppl_query, str):
     #     add_ppls.query(custom_ppl_query, inplace=True)
 
-    return ppl.append(add_ppls, sort=False, ignore_index=True, verify_integrity=True)
+    return pd.concat(
+        [ppl, add_ppls], sort=False, ignore_index=True, verify_integrity=True
+    )
 
 
 def replace_natural_gas_technology(df):