Distributed power harvesting systems using DC power sources
A distributed power harvesting system including multiple direct current (DC) power sources with respective DC outputs adapted for interconnection into an interconnected DC power source output. A converter includes input terminals adapted for coupling to the interconnected DC power source output. A circuit loop sets the voltage and current at the input terminals of the converter according to predetermined criteria. A power conversion portion converts the power received at the input terminals to an output power at the output terminals. A power supplier is coupled to the output terminals. The power supplier includes a control part for maintaining the input to the power supplier at a predetermined value. The control part maintains the input voltage and/or input current to the power supplier at a predetermined value.
1. A system comprising:
a plurality of photovoltaic panels connected in a series string, each comprising:
a plurality of input terminals connected to the plurality of photovoltaic panels in series;
a single diode connected in parallel across the plurality of input terminals and configured to bypass the plurality of input terminals; and
a direct current power converter comprising input terminals, output terminals, a control loop, and a controller, wherein:
the input terminals of the direct current power converter are configured to receive input power from the plurality of input terminals of the photovoltaic panels;
the direct current power converter is configured to convert the input power to output power at the output terminals;
the control loop is coupled to at least one of the input terminals of the power converter; and
the controller is configured to set, using the control loop, a voltage or a current at the input terminals of the power converter; and
an inverter comprising inverter input terminals, wherein the inverter is configured to receive power from the series string at the inverter input terminals.
2. The system of claim 1 , wherein the inverter comprises an inverter control loop, wherein the inverter is configured to control, using the inverter control loop, a voltage on the inverter input terminals to a predetermined value.
3. The system of claim 1 , wherein the inverter comprises an inverter control loop, wherein the inverter is configured to control, using the inverter control loop, a voltage on the inverter input terminals to less than an operational rating of components within the inverter.
4. The system of claim 1 , wherein the controller is configured to set, using the control loop, the voltage or the current at the input terminals according to a maximum power point algorithm.
5. The system of claim 1 , wherein the direct current power converter comprises one or more of a capacitor, an inductor, and a transistor.
6. The system of claim 1 , wherein the controller is configured to set the voltage or the current at the at least one input terminal according to a previously determined criterion.
7. The system of claim 6 , wherein the previously determined criterion comprises a maximum power point algorithm.
8. The system of claim 6 , wherein the previously determined criterion is a maximum power point of at least one of the plurality of photovoltaic panels.
9. The system of claim 1 , wherein the controller is configured to maximize, using the control loop, the input power.
10. The system of claim 1 , wherein the single diode is configured to bypass a current from flowing through the single diode in response to a failure of any photovoltaic panels of the plurality of photovoltaic panels or a shading of any photovoltaic panels of the plurality of photovoltaic panels.
11. The system of claim 1 , wherein the direct current power converter comprises a buck converter cascaded with a boost converter.
12. The system of claim 1 , wherein the direct current power converter comprises a buck converter serially connected to a boost converter.
13. The system of claim 1 , wherein the direct current power converter comprises a buck plus boost converter.
14. The system of claim 1 , further comprising a junction box configured to connect a plurality of PV assemblies, the junction box comprising a removeable bypass.