diff --git a/config/config.validation.yaml b/config/config.validation.yaml
index 052755d1..79aa3667 100644
--- a/config/config.validation.yaml
+++ b/config/config.validation.yaml
@@ -335,7 +335,7 @@ solar_thermal:
 
 # only relevant for foresight = myopic or perfect
 existing_capacities:
-  unit_commitment: true  # if unit commitment (UC) for conventional power plants is used
+  unit_commitment: false  # if unit commitment (UC) for conventional power plants is used
   # UC is only applied to extendable plants if  linearized UC is used
   grouping_years_power: [1980, 1985, 1990, 1995, 2000, 2005, 2010, 2015, 2020, 2025, 2030]
   grouping_years_heat: [1980, 1985, 1990, 1995, 2000, 2005, 2010, 2015, 2019] # these should not extend 2020
@@ -598,7 +598,8 @@ clustering:
   cluster_network:
     algorithm: kmeans
     feature: solar+onwind-time
-    exclude_carriers: []
+    exclude_carriers: ['onwind', 'solar', 'offwind-ac', 'CCGT', 'offwind-dc', 'lignite',
+       'ror', 'oil', 'biomass', 'coal', 'OCGT', 'nuclear']
   aggregation_strategies:
     generators:
       p_nom_max: sum # use "min" for more conservative assumptions
diff --git a/scripts/cluster_network.py b/scripts/cluster_network.py
index 7d3f7ffd..b9c5694f 100644
--- a/scripts/cluster_network.py
+++ b/scripts/cluster_network.py
@@ -457,7 +457,7 @@ if __name__ == "__main__":
     if "snakemake" not in globals():
         from _helpers import mock_snakemake
 
-        snakemake = mock_snakemake("cluster_network", simpl="", clusters="5")
+        snakemake = mock_snakemake("cluster_network", simpl="", clusters="37c")
     configure_logging(snakemake)
 
     n = pypsa.Network(snakemake.input.network)