diff --git a/config/config.default.yaml b/config/config.default.yaml
index 739cec2263..1eee9d0145 100644
--- a/config/config.default.yaml
+++ b/config/config.default.yaml
@@ -582,7 +582,7 @@ solar_thermal:
 # docs in https://pypsa-eur.readthedocs.io/en/latest/configuration.html#existing_capacities
 existing_capacities:
   grouping_years_power:
-  - 1920
+  - 1900
   - 1950
   - 1955
   - 1960
diff --git a/doc/release_notes.rst b/doc/release_notes.rst
index 28cf11ecaf..f4deeec727 100644
--- a/doc/release_notes.rst
+++ b/doc/release_notes.rst
@@ -9,6 +9,8 @@ Release Notes
 .. Upcoming Release
 .. =================
 
+* Fix: Lower the lower bound used to group the power plants in ``add_existing_baseyear`` (https://github.com/PyPSA/pypsa-eur/pull/2097). This now includes all power plants built since 1900.
+
 PyPSA-Eur v2026.02.0 (18th February 2026)
 =========================================
 
diff --git a/scripts/lib/validation/config/existing_capacities.py b/scripts/lib/validation/config/existing_capacities.py
index b98419ff38..cc39f84103 100644
--- a/scripts/lib/validation/config/existing_capacities.py
+++ b/scripts/lib/validation/config/existing_capacities.py
@@ -18,7 +18,7 @@ class ExistingCapacitiesConfig(ConfigModel):
 
     grouping_years_power: list[int] = Field(
         default_factory=lambda: [
-            1920,
+            1900,
             1950,
             1955,
             1960,