Performance ratio v1

pvlib/performance.py

@@ -0,0 +1,90 @@
+# -*- coding: utf-8 -*-
+"""
+Created on Wed Aug 5 14:51:04 2020
+
+@author: Saurabh
+
+"""
+
+from pvlib.temperature import sapm_cell
+from pvlib.pvsystem import pvwatts_dc
+
+
+
+def get_performance_ratio(poa_global, temp_air, wind_speed, pac, pdc0, a=-3.56, 
+                          b=-0.075, deltaT=3, gamma_pdc=-0.00433):
+
+    r'''
+    Calculate NREL Performance Ratio.
+
+    See equation [5] in Weather-Corrected Performance Ratio for details on 
+    the weighted method for Tref.
+
+    Parameters
+    ----------
+    poa_global : numeric
+        Total incident irradiance [W/m^2].
+
+    temp_air : numeric
+        Ambient dry bulb temperature [C].
+
+    wind_speed : numeric
+        Wind speed at a height of 10 meters [m/s].
+
+    pac : numeric
+        AC power [kW].
+
+    pdc0 : numeric
+        Power of the modules at 1000 W/m2 and cell reference temperature.
+
+    a : float
+        Parameter :math:`a` in :eq:`sapm1mod`.
+
+    b : float
+        Parameter :math:`b` in :eq:`sapm1mod`.
+
+    deltaT : float
+        Parameter :math:`\Delta T` in :eq:`sapm2` [C].
+
+    gamma_pdc : numeric
+                The temperature coefficient in units of 1/C. Typically -0.002 
+                to -0.005 per degree C.
+
+
+
+    Returns
+    -------
+    performance_ratio: numeric
+        Performance Ratio of data.
+
+
+    References
+    ----------
+    .. [1] "Weather-Corrected Performance Ratio". NREL, 2013. 
+    '''
+
+    #GET TMOD/TCELL FROM EXISTING PVLIB TEMPERATURE FUNCTION
+    cell_temperature = sapm_cell(poa_global, 
+                                 temp_air, 
+                                 wind_speed, 
+                                 a, 
+                                 b, 
+                                 deltaT
+                                 )
+
+    #Get weighted Tcell average
+    Tcell_poa_global = poa_global * cell_temperature
+    Tref = Tcell_poa_global.sum() / poa_global.sum()
+
+
+    #GET TEMPERATURE-CORRECTED DC ENERGY USING WEIGHTED TREF WITH PVLIB PVWATTS FUNCTION
+    pdc = pvwatts_dc(poa_global, 
+                     cell_temperature, 
+                     pdc0, 
+                     gamma_pdc, 
+                     temp_ref=Tref
+                     )
+
+    performance_ratio = pac.sum() / pdc.sum()
+
+    return performance_ratio