Systems and Methods to Balance Solar Panels in a Multi-Panel System

• US 20100127571A1
• Filed: 09/25/2009
• Published: 05/27/2010
• Est. Priority Date: 11/26/2008
• Status: Active Grant

• Current Assignee: Tigo Energy, Inc
• Original Assignee: Tigo Energy, Inc
• Inventors: HADAR, Ron, ARDITI, Shmuel
• Granted Patent: US 8,860,246 B2
• Time in Patent Office: Days
• US Class Current: 307/77
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources maximum power point systems in particular G05F1/67
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/46 Controlling of the sharing of output between the generators, converters, or transformers
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

Systems and methods to balance currents among a plurality of photovoltaic units connected in series. In aspect, a management unit is coupled between a photovoltaic energy production unit and a string of energy production units. The management unit has an energy storage element (e.g., a capacitor) connected to the photovoltaic energy production unit. The management unit further has a switch to selectively couple to the energy storage element and the photovoltaic energy production unit to the string. The management unit allows the current in the string to be larger than the current in the photovoltaic energy production unit.

Claims

1-20. -20. (canceled)

21. A management unit in a photovoltaic energy production system, comprising:

a circuit to periodically connect and disconnect a solar module to and from a power bus according to a duty cycle, the duty cycle being adjustable to operate the solar module at maximum power point; and

a controller to receive operating parameters from first management units coupled to the power bus, each of the first management units to determine operating parameters of a respective solar module and transmit the operating parameters of the respective solar module to the controller of the management unit, the controller to determine duty cycles for the first management units based at least in part on the operating parameters received from the first management units.

22. The management unit of claim 21, wherein the power bus is a serial power bus.

23. The management unit of claim 22, wherein each of the first management units has a switch to periodically connect and disconnect a respective solar module to and from the power bus;

and the controller is configured to determine different phases for respective switches in the first management units.

24. A photovoltaic energy production system, comprising:

a power bus;

a plurality of photovoltaic energy production units;

a plurality of first management units coupled between the plurality of photovoltaic energy production units and the power bus to supply electricity generated by the photovoltaic energy production units onto the bus, the first management units to determine operating parameters of the photovoltaic energy production units, each of the first management units being capable of adjusting a respective photovoltaic energy production unit to a maximum power point of the respective photovoltaic energy production unit; and

a second managements unit in communication with the first management units to receive the operating parameters of the photovoltaic energy production units, the second management unit to determine at least one parameter for the first management units, the first management units to operate at least one of the photovoltaic energy production units at a maximum power point according to the at least one parameter.

25. The system of claim 24, wherein the power bus is a string bus;

and the plurality of first management units connect the plurality of photovoltaic energy production units in series on the string bus.

26. The system of claim 24, wherein the second management unit communicates with first management units over the power bus.

27. A method, comprising:

receiving, from a plurality of first management units and by a second management unit, operating parameters of a plurality of solar modules, each of the plurality of first management units being coupled with a respective solar module of the plurality of solar modules to determine operating parameters of the respective solar module and coupled between the respective solar module and a power bus to supply electricity generated by the respective solar module onto the power bus;

determining, by the second management unit, at least one control parameter based on the operating parameters of the plurality of solar modules; and

transmitting, by the second management unit, the at least one control parameter to the first management units to operate at least one of the solar modules at maximum power point.

28. The method of claim 27, wherein the power bus comprises a string of the plurality of first management units connected in series.

29. The method of claim 27, further comprising:

calculating, by the second management unit, estimated maximum power points of the solar modules, wherein the at least one control parameter is determined based on the estimated maximum power points of the solar modules.

30. The method of claim 27, further comprising:

electing the second management unit from a plurality of management units connected on the power bus.

31. A photovoltaic energy production system, comprising:

a power bus;

a plurality of photovoltaic energy production units;

a plurality of first management units coupled between the plurality of photovoltaic energy production units and the power bus to supply electricity generated by the photovoltaic energy production units onto the bus, the first management units to determine operating parameters of the photovoltaic energy production units, each of the first management units being capable of adjusting a respective photovoltaic energy production unit to a maximum power point of the respective photovoltaic energy production unit; and

an inverter coupled to the power bus to receive the electricity generated by the photovoltaic energy production units, the inverter configured to track maximum power point while receiving the electricity from the power bus.

32. The system of claim 31, wherein the power bus is a string bus;

and the plurality of first management units connect the plurality of photovoltaic energy production units in series on the string bus.

33. The system of claim 31, wherein the inverter performs maximum power point tracking on the power bus, while at least one of the first management units adjusts a respective photovoltaic energy production unit to a maximum power point.

34. The system of claim 31, further comprising:

a second management unit configured to determine at least one control parameter for the first management units, wherein each of the first management units is configured to adjust a respective photovoltaic energy production unit based on the control parameter.

35. The system of claim 34, wherein the second management unit is configured to determine a plurality of values of the control parameter for the plurality of first management units respectively.

36. A method, comprising:

transmitting, from a plurality of first management units, operating parameters of a plurality of solar modules, each of the plurality of first management units being coupled with a respective solar module of the plurality of solar modules to determine operating parameters of the respective solar module and coupled between the respective solar module and a power bus to supply electricity generated by the respective solar module onto the power bus;

receiving, by the first management units, at least one control parameter to operate at least one of the solar modules at maximum power point, wherein the at least one control parameter is determined based on the operating parameters of the plurality of solar modules; and

performing, by an inverter connected to the power bus, maximum power point tracking, while the inverter receives electricity from the power bus.

37. The method of claim 36, further comprising:

measuring the operating parameters of the plurality of solar modules by the plurality of first management units while the inverter performing maximum power point tracking.

38. The method of claim 36, further comprising:

stopping maximum power point tracking at the inverter while measuring the operating parameters of the plurality of solar modules by the plurality of first management units; and

resuming maximum power point tracking at the inverter after measuring the operating parameters of the plurality of solar modules by the plurality of first management units.

39. The method of claim 36, wherein at least one of the first management units adjusts at least one of the solar modules according to the control parameter, while the maximum power point tracking is performed by the inverter.

40. The method of claim 39, wherein the control parameter is selected from the group consisting of:

duty cycle, phase shift, and synchronization pulse.