Fix ZeroDivisionError in simple_efficiency when load_loss=0

Author: aman-coder03

pvlib/transformer.py

@@ -105,11 +105,14 @@ def simple_efficiency(
        pg. 101.
     '''  # noqa: E501
 
+    if load_loss == 0:
+        return input_power - no_load_loss * transformer_rating
+
     input_power_normalized = input_power / transformer_rating
 
     a = load_loss
     b = 1
-    c = no_load_loss - input_power_normalized
+    c = no_load_loss - input_power_normalized   
 
     output_power_normalized = (-b + (b**2 - 4*a*c)**0.5) / (2 * a)