diff --git a/pp2psdm/grid.py b/pp2psdm/grid.py
index d9e7347..f6d7ee9 100644
--- a/pp2psdm/grid.py
+++ b/pp2psdm/grid.py
@@ -46,64 +46,35 @@ def convert_grid(
     return net, uuid_idx
 
 def convert_nodes(grid):
-    nodes_data = {}
-
     df = grid.bus
-    
-    list_node_id = []
-    nodes_geo_position_list = []
-    list_subnets = []
-    v_rated_list = []
-    v_target_list = []
-    volt_lvl_list = []
-    operates_from_list = []
-    operates_until_list = []
-    slack_list = []
-    
-    for idx, row in df.iterrows():
-
-        # Get operation times
-        operates_from, operates_until = get_operation_times(row)
-
-        # Determine the voltage level (vlt_lvl or vn_kv)
-        if "vlt_lvl" in df.columns and not pd.isna(row["vlt_lvl"]):
-            volt_lvl = row["vlt_lvl"]
-        else:
-            volt_lvl = row["vn_kv"]
 
-        # Determine the subnet (subnet, zone, or fixed number)
-        if "zone" in df.columns and not pd.isna(row["zone"]):
-            subnet = row["zone"]
-        else:
-            subnet = 101
+    def get_default(value, default):
+        return value if not pd.isna(value) else default
 
-        # In case there is a uuid column use it else generate uuids
-        if "uuid" in df.columns and not pd.isna(row["uuid"]):
-            uuid = row["uuid"]
-        else:
-            uuid = uuid4().__str__()
-
-        list_node_id = list_node_id + [row["name"]]
-        nodes_geo_position_list = nodes_geo_position_list + [None]
-        list_subnets = list_subnets + [subnet]
-        v_rated_list = v_rated_list + [row["vn_kv"]]
-        v_target_list = v_target_list + [row["vn_kv"]]
-        volt_lvl_list = volt_lvl_list+[volt_lvl]
-        operates_from_list = operates_from_list + [operates_from]
-        operates_until_list = operates_until_list + [operates_until]
-        slack_list=slack_list + ['false']
-        
-    
     data_dict = {
-        "id": list_node_id,
-        "geo_position": nodes_geo_position_list,
-        "subnet": list_subnets,
-        "v_rated": v_rated_list,
-        "v_target": v_target_list,
-        "volt_lvl": volt_lvl_list,
-        "slack": slack_list,
+        "id": df["name"].tolist(),
+        "geo_position": [None] * len(df),
+        "subnet": [
+            get_default(row.get("zone"), 101)
+            for _, row in df.iterrows()
+        ],
+        "v_rated": df["vn_kv"].tolist(),
+        "v_target": df["vn_kv"].tolist(),
+        "volt_lvl": [
+            get_default(row.get("vlt_lvl"), row["vn_kv"])
+            for _, row in df.iterrows()
+        ],
+        "slack": ['false'] * len(df),
+        "operates_from": [
+            get_operation_times(row)[0]
+            for _, row in df.iterrows()
+        ],
+        "operates_until": [
+            get_operation_times(row)[1]
+            for _, row in df.iterrows()
+        ]
     }
-    
+
     return create_nodes(data_dict)