diff --git a/Utilities/BESS.py b/Utilities/BESS.py
index 8fd4bc2..76ffb35 100644
--- a/Utilities/BESS.py
+++ b/Utilities/BESS.py
@@ -92,8 +92,13 @@ def update_cycle_SoC(bess_data, bess_soc_for_cycle, timestamps):
             axis=0,
         )
 
+
 def arrange_swap(bess_data, c):
     for unit in bess_data["units"]:
-        if unit["SoC"] < c["bess"]["buffer"]:   
+        if unit["SoC"] < c["bess"]["buffer"]:
             # find for unassigned BESS unit with SOC at 100%
-                
\ No newline at end of file
+            for candidate in bess_data["units"]:
+                if candidate["SoC"] == 1 and candidate["site"] == "Unassigned":
+                    # assign the candidate to the site
+                    candidate["site"] = unit["site"]
+                    break