add fast_v_from_i using newton

pvlib · wholmgren · Jul 10, 2018 · Jan 27, 2018 · Jan 27, 2018 · Jan 27, 2018
commit 09a9e147564ae9bd520a26b860b6fc2dd3a6799f
diff --git a/pvlib/way_faster.py b/pvlib/way_faster.py
@@ -112,6 +112,21 @@ def slow_v_from_i(i, photocurrent, saturation_current, resistance_series,
    return bishop88(vd, *args)[1]


+def fast_v_from_i(i, photocurrent, saturation_current, resistance_series,
+                  resistance_shunt, nNsVth):
+    """
+    This is a fast but unreliable way to find voltage given any current.
+    """
+    # collect args
+    args = (photocurrent, saturation_current, resistance_series,
+            resistance_shunt, nNsVth)
+    # first bound the search using voc
+    voc_est = est_voc(photocurrent, saturation_current, nNsVth)
+    vd = newton(func=lambda x, *a: bishop88(x, *a)[0] - i, x0=voc_est,
+                fprime=lambda x, *a: bishop88(x, *a)[2], args=args)
+    return bishop88(vd, *args)[1]
+
+
 def slow_mppt(photocurrent, saturation_current, resistance_series,
              resistance_shunt, nNsVth):
    """
-Original file line number
+Diff line change
@@ -112,6 +112,21 @@ def slow_v_from_i(i, photocurrent, saturation_current, resistance_series,
         return bishop88(vd, *args)[1]
+    def fast_v_from_i(i, photocurrent, saturation_current, resistance_series,
+                      resistance_shunt, nNsVth):
+        """
+        This is a fast but unreliable way to find voltage given any current.
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            markcampanelli
  

      

      

      


        Feb 1, 2018


      
    

  


        
      
  
  
  
    

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      I'm not sure if "unreliable" is the best choice of words here. It's more of an "unchecked" result.
    
  
  


    

        
      
  
  
    
  
  
  
    
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            mikofski
  

      

      

      


        Feb 1, 2018


      
    

  


        
      
  
  
  
    

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      ✔️
    
  
  


    

        
      
  
  
    
  
  
  
    
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+        """
+        # collect args
+        args = (photocurrent, saturation_current, resistance_series,
+                resistance_shunt, nNsVth)
+        # first bound the search using voc
+        voc_est = est_voc(photocurrent, saturation_current, nNsVth)
+        vd = newton(func=lambda x, *a: bishop88(x, *a)[0] - i, x0=voc_est,
+                    fprime=lambda x, *a: bishop88(x, *a)[2], args=args)
+        return bishop88(vd, *args)[1]
     def slow_mppt(photocurrent, saturation_current, resistance_series,
                   resistance_shunt, nNsVth):
         """
-          Expand Down