diff --git a/src/pymgrid/MicrogridGenerator.py b/src/pymgrid/MicrogridGenerator.py
index 0510bccc..1b20b6eb 100644
--- a/src/pymgrid/MicrogridGenerator.py
+++ b/src/pymgrid/MicrogridGenerator.py
@@ -380,7 +380,7 @@ def _size_genset(self, load, max_operating_loading = 0.9):
         #random number > 3 < 20
         # polynomial for fuel consumption
 
-        _size_genset = int(np.ceil(np.max(load)/max_operating_loading))
+        _size_genset = int(np.ceil(np.max(load, axis=0)/max_operating_loading))
 
         return _size_genset
 
@@ -388,7 +388,7 @@ def _size_genset(self, load, max_operating_loading = 0.9):
     def _size_battery(self, load):
         """ Function that returns the capacity of the battery, equivalent to 3 to 5 hours of mean load. """
         #energy duration
-        battery = int(np.ceil(np.random.randint(low=3,high=6)*np.mean(load).item()))
+        battery = int(np.ceil(np.random.randint(low=3,high=6)*np.mean(load, axis=0).item()))
         return battery