refactor ModelChain. add SingleDiode modelchain

Author: wholmgren

pvlib/modelchain.py

@@ -208,7 +208,7 @@ def get_orientation(strategy, **kwargs):
 
 class ModelChain(object):
     """
-    An experimental class that represents all of the modeling steps
+    An experimental base class that represents all of the modeling steps
     necessary for calculating power or energy for a PV system at a given
     location.
 
@@ -278,7 +278,7 @@ def orientation_strategy(self, strategy):
 
         self._orientation_strategy = strategy
 
-    def run_model(self, times, irradiance=None, weather=None):
+    def prepare_inputs(self, times, irradiance=None, weather=None):
         """
         Run the model.
 
@@ -301,15 +301,19 @@ def run_model(self, times, irradiance=None, weather=None):
         self
 
         Assigns attributes: times, solar_position, airmass, irradiance,
-        total_irrad, weather, temps, aoi, dc, ac
+        total_irrad, weather, aoi
         """
+
         self.times = times
 
         self.solar_position = self.location.get_solarposition(self.times)
 
         self.airmass = self.location.get_airmass(
             solar_position=self.solar_position, model=self.airmass_model)
 
+        self.aoi = self.system.get_aoi(self.solar_position['apparent_zenith'],
+                                       self.solar_position['azimuth'])
+
         if irradiance is None:
             irradiance = self.location.get_clearsky(
                 self.solar_position.index, self.clearsky_model,
@@ -329,13 +333,39 @@ def run_model(self, times, irradiance=None, weather=None):
             weather = {'wind_speed': 0, 'temp_air': 20}
         self.weather = weather
 
+        return self
+
+    def run_model(self):
+        """
+        A stub function meant to be subclassed.
+        """
+        raise NotImplementedError(
+            'you must subclass ModelChain and implement this method')
+
+
+class SAPM(ModelChain):
+    """
+    Uses the SAPM to calculate cell temperature, DC power and AC power.
+    """
+    def run_model(self):
+        """
+        Run the model.
+
+        Parameters
+        ----------
+
+        Returns
+        -------
+        self
+
+        Assigns attributes: temps, dc, ac
+        """
+
+
         self.temps = self.system.sapm_celltemp(self.total_irrad['poa_global'],
                                                self.weather['wind_speed'],
                                                self.weather['temp_air'])
 
-        self.aoi = self.system.get_aoi(self.solar_position['apparent_zenith'],
-                                       self.solar_position['azimuth'])
-
         self.dc = self.system.sapm(self.total_irrad['poa_direct'],
                                    self.total_irrad['poa_diffuse'],
                                    self.temps['temp_cell'],
@@ -345,3 +375,45 @@ def run_model(self, times, irradiance=None, weather=None):
         self.ac = self.system.snlinverter(self.dc['v_mp'], self.dc['p_mp'])
 
         return self
+
+
+class SingleDiode(ModelChain):
+    """
+    Uses the DeSoto and single diode models to calculate the DC power,
+    and the SAPM models to calculate cell temperature and AC power.
+    """
+
+    def run_model(self):
+        """
+        Run the model.
+
+        Parameters
+        ----------
+
+        Returns
+        -------
+        self
+
+        Assigns attributes: temps, dc, ac
+        """
+
+
+        self.temps = self.system.sapm_celltemp(self.total_irrad['poa_global'],
+                                               self.weather['wind_speed'],
+                                               self.weather['temp_air'])
+
+        (photocurrent, saturation_current, resistance_series,
+         resistance_shunt, nNsVth) = (
+            self.system.calcparams_desoto(self.total_irrad['poa_global'],
+                                          self.temps['temp_cell']))
+
+        self.desoto = (photocurrent, saturation_current, resistance_series,
+                       resistance_shunt, nNsVth)
+
+        self.dc = self.system.singlediode(
+            photocurrent, saturation_current, resistance_series,
+            resistance_shunt, nNsVth)
+
+        self.ac = self.system.snlinverter(self.dc['v_mp'], self.dc['p_mp'])
+
+        return self