Bug fix

Author: SabineHaas

windpowerlib/wind_farm.py

@@ -260,8 +260,9 @@ def assign_power_curve(self, wake_losses_model='power_efficiency_curve',
                 # can occure problems during the aggregation
                 if power_curve.iloc[0]['wind_speed'] != 0.0:
                     power_curve = pd.concat(
-                        [power_curve, pd.DataFrame(data={
-                            'power': [0.0], 'wind_speed': [0.0]})], sort=True)
+                        [pd.DataFrame(data={
+                            'power': [0.0], 'wind_speed': [0.0]}),
+                         power_curve], sort=True)
                 if power_curve.iloc[-1]['power'] != 0.0:
                     power_curve = pd.concat(
                         [power_curve, pd.DataFrame(data={