Distributed Power Harvesting Systems Using DC Power Sources

Abstract

A photovoltaic panel with multiple photovoltaic sub-strings including serially-connected photovoltaic cells and having direct current (DC) outputs adapted for interconnection in parallel into a parallel-connected DC power source. A direct current (DC) power converter including input terminals and output terminals is adapted for coupling to the parallel-connected DC power source and for converting an input power received at the input terminals to an output power at the output terminals. The direct current (DC) power converter optionally has a control loop configured to set the input power received at the input terminals according to a previously determined criterion. The control loop may be adapted to receive a feedback signal from the input terminals for maximizing the input power. A bypass diode is typically connected in shunt across the input terminals of the converter. The bypass diode functions by passing current during a failure of any of the sub-strings and/or a partial shading of the sub-strings. The bypass diode may be a single bypass diode connected across the parallel-connected DC power source. The DC power converter may convert the input power at high current to the output power at a lower current. The output terminals may be connectible with wire cables to a load, and the DC power converter is configured to reduce energy loss through the wire cables to the load.

1 - 17 . (canceled) 
     
     
         18 . A system comprising:
 a string comprising:
 a plurality of photovoltaic panels; and 
 a plurality of power converters connected in series, wherein: 
 each one of the plurality of power converters is coupled with a corresponding one of the plurality of photovoltaic panels, 
 each one of the plurality of power converters is configured to draw power from the corresponding one of the plurality of photovoltaic panels according to a corresponding maximum power point tracking (MPPT) algorithm, and 
 at least two of the plurality of photovoltaic panels are building integrated photovoltaic panels. 
   
     
     
         19 . The system of  claim 18 , further comprising an inverter coupled to the string, wherein the inverter is configured to regulate a common voltage across inputs of the inverter. 
     
     
         20 . The system of  claim 18 , wherein each of the plurality of power converters is configured to limit, based on a condition, an output voltage of the power converter to a safe level. 
     
     
         21 . The system of  claim 20 , wherein the condition is one of a predetermined minimum load, or a signal sent from an inverter. 
     
     
         22 . The system of  claim 19 , further comprising a battery connected to the inverter, wherein the inverter is configured to charge the battery with power provided by the string. 
     
     
         23 . The system of  claim 18 , further comprising a second string, the second string comprising:
 a second plurality of photovoltaic panels; and   a second plurality of power converters connected in series, wherein:   each one of the second plurality of power converters is coupled with a corresponding one of the second plurality of photovoltaic panels,   each one of the second plurality of power converters is configured to draw power from the corresponding one of the second plurality of photovoltaic panels according to a corresponding maximum power point tracking (MPPT) algorithm, and   at least two of the second plurality of photovoltaic panels are building integrated photovoltaic panels.   
     
     
         24 . The system of  claim 23 , wherein a number of the plurality of photovoltaic panels of the string, is different from a number of the second plurality of photovoltaic panels. 
     
     
         25 . The system of  claim 18 , wherein each of the plurality of power converters comprises one of:
 buck converter circuitry;   boost converter circuitry;   buck-boost converter circuitry; or   buck plus boost converter circuitry.   
     
     
         26 . The system of  claim 18 , wherein each of the plurality of power converters is configured to selectively operate in at least one of a buck conversion mode, a boost conversion mode, or a buck-boost conversion mode. 
     
     
         27 . The system of  claim 23 , wherein each of the at least two of the plurality of photovoltaic panels is integrated with a roof, a window, or a wall. 
     
     
         28 . The system of  claim 23 , wherein each of the at least two of the plurality of photovoltaic panels is a roof tile. 
     
     
         29 . The system of  claim 18 , wherein the at least two of the plurality of photovoltaic panels are associated with different facets of a building. 
     
     
         30 . A system comprising:
 a string comprising:
 a plurality of serially connected photovoltaic panels; and 
 a power converter coupled across the plurality of serially connected photovoltaic panels, wherein:
 the power converter is configured to draw power from the plurality of serially connected photovoltaic panels according to a maximum power point tracking (MPPT) algorithm, and 
 at least two photovoltaic panels of the plurality of serially connected photovoltaic panels are building integrated photovoltaic panels. 
 
   
     
     
         31 . The system of  claim 30 , further comprising an inverter connected to the string, wherein the inverter is configured to regulate a common voltage across inputs of the string. 
     
     
         32 . The system of  claim 30 , wherein the power converter is configured to limit, based on a condition, an output voltage of the power converter to a safe level. 
     
     
         33 . The system of  claim 32 , wherein the condition is one of a predetermined minimum load, or a signal sent from an inverter. 
     
     
         34 . The system of  claim 31 , further comprising a battery connected to the inverter, wherein the inverter is configured to charge the battery with power provided by the string. 
     
     
         35 . The system of  claim 30 , further comprising a second string, the second string comprising:
 a second plurality of serially connected photovoltaic panels; and   a second power converter coupled across the second plurality of serially connected photovoltaic panels, wherein:   the second power converter is configured to draw power from the second plurality of serially connected photovoltaic panels according to a maximum power point tracking (MPPT) algorithm, and   at least two photovoltaic panels of the second plurality of serially connected photovoltaic panels are building integrated photovoltaic panels.   
     
     
         36 . The system of  claim 35 , where a number of the plurality of serially connected photovoltaic panels is different from a number of the second plurality of serially connected photovoltaic panels. 
     
     
         37 . The system of  claim 30 , wherein each of the at least two photovoltaic panels is integrated with a roof, a window, or a wall. 
     
     
         38 . The system of  claim 30 , wherein each of the at least two photovoltaic panels is a roof tile. 
     
     
         39 . A photovoltaic string comprising:
 a plurality of photovoltaic panels; and   a plurality of power converters connected in series, wherein:   each one of the plurality of power converters is connected to a corresponding one of the plurality of photovoltaic panels,   each one of the plurality of power converters is configured to draw power from the corresponding one of the plurality of photovoltaic panels according to a corresponding maximum power point tracking (MPPT) algorithm, and   at least two of the plurality of photovoltaic panels are building integrated photovoltaic panels.