diff --git a/config/config.default.yaml b/config/config.default.yaml
index cca5018f..5a32e61c 100644
--- a/config/config.default.yaml
+++ b/config/config.default.yaml
@@ -579,6 +579,7 @@ clustering:
     algorithm: kmeans
     feature: solar+onwind-time
     exclude_carriers: []
+    consider_efficiency_classes: false
   aggregation_strategies:
     generators:
       committable: any
diff --git a/config/config.validation.yaml b/config/config.validation.yaml
index ff1f87ce..bc0b0048 100644
--- a/config/config.validation.yaml
+++ b/config/config.validation.yaml
@@ -9,11 +9,9 @@ scenario:
   ll:  # allowed transmission line volume expansion, can be any float >= 1.0 with a prefix v|c (today) or "copt"
   - v1.0
   clusters:  # number of nodes in Europe, any integer between 37 (1 node per country-zone) and several hundred
-  - 37c
+  - 37
   opts: # only relevant for PyPSA-Eur
   - 'Ept'
-  sector_opts: # this is where the main scenario settings are
-  - Co2L0-1H-T-H-B-I-A-solar+p3-dist1
 
 snapshots:
   start: "2019-01-01"
@@ -96,12 +94,17 @@ costs:
   emission_prices: # in currency per tonne emission, only used with the option Ep
     co2: 25
 
+clustering:
+  simplify_network:
+    exclude_carriers: [oil, coal, lignite, OCGT, CCGT]
+  cluster_network:
+    consider_efficiency_classes: true
 
 
 solving:
   #tmpdir: "path/to/tmp"
   options:
     load_shedding: true
-    rolling_horizon: true
-    horizon: 365
+    rolling_horizon: false
+    horizon: 389
     overlap: 24
diff --git a/scripts/cluster_network.py b/scripts/cluster_network.py
index f0fd80eb..65a3c36c 100644
--- a/scripts/cluster_network.py
+++ b/scripts/cluster_network.py
@@ -461,7 +461,7 @@ if __name__ == "__main__":
     if "snakemake" not in globals():
         from _helpers import mock_snakemake
 
-        snakemake = mock_snakemake("cluster_network", simpl="", clusters="37c")
+        snakemake = mock_snakemake("cluster_network", simpl="", clusters="37")
     configure_logging(snakemake)
 
     params = snakemake.params
@@ -483,6 +483,23 @@ if __name__ == "__main__":
     else:
         n_clusters = int(snakemake.wildcards.clusters)
 
+    if params.cluster_network["consider_efficiency_classes"]:
+        carriers = []
+        for c in aggregate_carriers:
+            gens = n.generators.query("carrier == @c")
+            low = gens.efficiency.quantile(0.10)
+            high = gens.efficiency.quantile(0.90)
+            if low >= high:
+                carriers += [c]
+            else:
+                labels = ["low", "medium", "high"]
+                suffix = pd.cut(
+                    gens.efficiency, bins=[0, low, high, 1], labels=labels
+                ).astype(str)
+                carriers += [f"{c} {label} efficiency" for label in labels]
+                n.generators.carrier.update(gens.carrier + " " + suffix + " efficiency")
+        aggregate_carriers = carriers
+
     if n_clusters == len(n.buses):
         # Fast-path if no clustering is necessary
         busmap = n.buses.index.to_series()
@@ -524,6 +541,11 @@ if __name__ == "__main__":
 
     update_p_nom_max(clustering.network)
 
+    if params.cluster_network.get("consider_efficiency_classes"):
+        labels = [f" {label} efficiency" for label in ["low", "medium", "high"]]
+        nc = clustering.network
+        nc.generators["carrier"] = nc.generators.carrier.replace(labels, "", regex=True)
+
     clustering.network.meta = dict(
         snakemake.config, **dict(wildcards=dict(snakemake.wildcards))
     )