REDUNDANT ELECTRICAL ARCHITECTURE FOR PHOTOVOLTAIC MODULES

• US 20090183760A1
• Filed: 01/21/2009
• Published: 07/23/2009
• Est. Priority Date: 01/18/2008
• Status: Active Grant

• Current Assignee: Spectrum Solar, LLC
• Original Assignee: Tenksolar, Inc.
• Inventors: Meyer, Dallas W.
• Granted Patent: US 8,933,320 B2
• Time in Patent Office: Days
• US Class Current: 136/244
• CPC Class Codes: H01L 31/02008 for solar cells or solar cell modules
• CPC Class Codes: H01L 31/042 PV modules or arrays of single PV cells supporting structures for PV modules H02S20/00
• CPC Class Codes: H02M 7/003 Constructional details, e.g. physical layout, assembly, wiring or busbar connections
• CPC Class Codes: H02S 50/00 Monitoring or testing of PV systems, e.g. load balancing or fault identification
• CPC Class Codes: H02S 50/10 Testing of PV devices, e.g. of PV modules or single PV cells testing of semiconductor devices during manufacturing H01L22/00
• CPC Class Codes: H02S 50/15 using optical means, e.g. using electroluminescence
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

One example embodiment includes a PV module comprising a conductive backsheet, a substantially transparent front plate, a plurality of PV cells, a plurality of conductive spacers, and a power conversion device. The PV cells can be disposed between the conductive backsheet and the front plate and can be arranged in a plurality of rows. The PV cells within each row can be connected to each other in parallel and the rows can be connected in series. The PV cells can be interconnected between the conductive spacers. The power conversion device can be redundantly connected to the PV cells via a last conductive spacer connected to a last row. The power conversion device can substantially maintain a maximum peak power of the PV module and can convert a lower voltage collectively generated by the PV cells to a predetermined stepped up voltage greater than or equal to 12 volts.

Claims

1. A photovoltaic module, comprising:

a conductive backsheet;

a substantially transparent front plate;

a plurality of photovoltaic cells disposed between the conductive backsheet and the front plate, the photovoltaic cells arranged in a plurality of rows, the photovoltaic cells in each row being connected in parallel and the rows being connected in series;

a plurality of conductive spacers that the plurality of rows are interconnected between; and

a power conversion device redundantly connected to the plurality of photovoltaic cells via a last conductive spacer connected to a last row, the power conversion device substantially maintaining a maximum peak power of the photovoltaic module and converting a lower voltage collectively generated by the plurality of photovoltaic cells to a predetermined stepped up voltage greater than or equal to 12 volts.

2. The photovoltaic module of claim 1, wherein the plurality of photovoltaic cells collectively generate a 3-12 volt power supply, and wherein the power conversion device is self-starting from the 3-12 volt power supply collectively generated by the plurality of photovoltaic cells without an external power supply.

3. The photovoltaic module of claim 1, wherein the power conversion device includes a plurality of power conversion circuits, an input bus, and output bus, the plurality of power conversion circuits coupled to each other in parallel between the input bus and the output bus, and the input bus coupled to the last conductive spacer.

4. The photovoltaic module of claim 3, wherein each of the plurality of power conversion circuits includes a control module executing firmware to regulate an output voltage of each of the plurality of power conversion circuits to the predetermined stepped up voltage.

5. The photovoltaic module of claim 4, wherein each of the plurality of power conversion circuits includes a switch and wherein the control module in each of the plurality of power conversion circuits controls a duty cycle of the corresponding switch to regulate the output voltage of each power conversion circuit to the predetermined stepped up voltage.

6. The photovoltaic module of claim 4, wherein the predetermined stepped up voltage matches a load voltage of a load driven by the photovoltaic module.

7. The photovoltaic module of claim 3, wherein each power conversion circuit has a current capacity of at least 3 times a current collectively generated by the plurality of photovoltaic cells under 1 sun of illumination divided by a quantity of the plurality of power conversion circuits.

8. The photovoltaic module of claim 3, wherein the power conversion device detects failed power conversion circuits and removes the failed power conversion circuits from operation.

9. The photovoltaic module of claim 8, wherein the power conversion device includes one or more fuses to detect the failed power conversion circuits and remove the failed power conversion circuits from operation.

10. The photovoltaic module of claim 3, wherein each of the plurality of power conversion circuits comprises a boost converter, a buck/boost converter, a SEPIC converter, or a Ć

uk converter, each of the plurality of power conversion circuits converting the voltage of an incremental amount of power generated by the plurality of photovoltaic cells to the predetermined stepped up voltage and providing the converted incremental amount of power to the output bus.

11. The photovoltaic module of claim 3, wherein the maximum peak power of the photovoltaic module and the voltage gain of the power conversion device are controlled by adjusting a frequency, duty cycle and phasing of one or more pulse-width-modulated control signals for one or more of the power conversion circuits, each pulse-width-modulated control signal being generated by a control module included in the corresponding power conversion circuit or by one or more external crystal oscillators.

12. The photovoltaic module of claim 3 wherein the power conversion device includes at least one control module and the plurality of power conversion circuits include one or more redundant power conversion circuits such that when one power conversion circuit that is switched on fails, the control module switches off the failed power conversion circuit and switches on a redundant power conversion circuit that was previously switched off.

13. The photovoltaic module of claim 3, wherein a plurality of power conversion circuits that are switched on operate out of phase with each other to minimize current ripple at an input and output of the power conversion device.

14. The photovoltaic module of claim 3, wherein each of the plurality of power conversion circuits operates with a spread spectrum switching frequency.

15. The photovoltaic module of claim 3, wherein:

each of the plurality of power conversion circuits includes a control module;

or

the power conversion device includes a plurality of control modules, each control module controlling two or more of the plurality of power conversion circuits.

16. The photovoltaic module of claim 1, wherein the predetermined stepped up voltage is less than 60 volts, the photovoltaic module further comprising one or more ground fault detection devices configured to automatically shunt current supply back into the photovoltaic module upon detecting a fault condition such that the power conversion device discharges less than 24 joules of energy after detecting the fault condition.

17. The photovoltaic module of claim 1, wherein the power conversion device substantially maintains maximum peak power by implementing a circuit switching method and one or more of:

an AC ripple control method, a perturb and observe method, or a fixed Voc offset method.

18. The photovoltaic module of claim 1, further comprising an identifier that identifies the photovoltaic module, and a communication interface for digitally communicating bi-directionally with an external source using a defined communication protocol.

19. The photovoltaic module of claim 18, wherein the identifier comprises one or more of a:

unique serial identifier or a unique internet protocol address, and the defined protocol comprises one or more of Internet Protocol, Ethernet, Wireless Ethernet, Fibre Channel, Transmission Control Protocol, Sonet, or code division multiple access.

20. The photovoltaic module of claim 1, further comprising a control module included in the power conversion device, the control module configured to calculate future performance of the photovoltaic module based on information stored in the photovoltaic module, information stored externally, or both.

21. The photovoltaic module of claim 1, wherein the power conversion device comprises a first voltage gain stage including a first plurality of power conversion circuits and a second voltage gain stage including a second plurality of power conversion circuits, an input of the second voltage gain stage being coupled to an output of the first voltage gain stage.

22. The photovoltaic module of claim 1, further comprising a plurality of bypass diodes, the bypass diodes coupled together in series and each bypass diode coupled to a corresponding row such that current can flow around a row when it is blocked.

23. The photovoltaic module of claim 1, further comprising an active row-balancing device individually coupled to at least some of the plurality of conductive spacers, the active row-balancing device feeding current into one or more of the plurality of rows to maximize power output of the photovoltaic module.

24. The photovoltaic module of claim 23, wherein the active row-balancing device comprises a plurality of active electronic devices, and wherein the plurality of active electronic devices draw operating power from a power output of the power conversion device.

25. The photovoltaic module of claim 24, wherein the photovoltaic module implements a nested control loop in the power conversion device and active row-balancing device to maintain maximum peak power and convert the lower voltage to the predetermined stepped up voltage, the power conversion device comprising a plurality of power conversion circuits and the nested control loop including:

a first loop implemented within each of the power conversion circuits to maintain maximum peak power within each of the power conversion circuits;

a second loop implemented within each of the power conversion circuits to convert the lower voltage to the predetermined stepped up voltage;

a third loop implemented across the power conversion circuits within the power conversion device to maximize the efficiency of the power conversion circuits; and

a fourth loop implemented within the power conversion device and the active row-balancing device to actively balance current across the plurality of rows.

26. The photovoltaic module of claim 25, wherein the third control loop includes on/off cycling of the power conversion circuits.

27. A method of calibrating a photovoltaic module, comprising:

downloading a first set of computer executable instructions onto a photovoltaic module comprising a power conversion device including a plurality of power conversion circuits, the first set of computer executable instructions configured to control operation of the photovoltaic module during calibration;

exposing the photovoltaic module to multiple illumination intensities;

exposing the photovoltaic module to multiple ambient temperatures;

generating measurement data for each illumination intensity and ambient temperature, the measurement data representative of one or more of;

an electrical resistance of each power conversion circuit;

a power output of each power conversion circuit;

a peak power current of each power conversion circuit;

a peak power voltage of each power conversion circuit; and

a local circuit phase of each power conversion circuit;

generating a plurality of calibration curves from the measurement data;

storing the plurality of calibration curves in a memory of the photovoltaic module, the plurality of calibration curves allowing a control module of the photovoltaic module to transform measurements in the field into physical data; and

replacing the first set of computer executable instructions with a second set of computer executable instructions configured to control operation of the photovoltaic module in the field.

28. The method of claim 27, wherein the measurement data is generated internally within the photovoltaic module.

29. The method of claim 27, wherein the measurement data includes data representative of one or more of:

normalized maximum power output of the photovoltaic module, short circuit current of the photovoltaic module, open circuit voltage of the photovoltaic module, maximum peak power current of the photovoltaic module, maximum peak power voltage of the photovoltaic module, parasitic resistance of the photovoltaic module, shunt resistance of the photovoltaic module, reverse current bias of the photovoltaic module, reverse voltage bias of the photovoltaic module, frequency response of each power conversion circuit, capacitance of each power conversion circuit, inductance of each power conversion circuit, circuit tuning parameters of each power conversion circuit, switching times of each power conversion circuit, or phasing of each power conversion circuit.

30. The method of claim 29, further comprising collecting and storing trend analysis data representative of one or more of:

a time and date, an ambient temperature of the photovoltaic module, an operating temperature of each of the power conversion circuits, an illumination intensity of the photovoltaic module, an output voltage of the power conversion device, an amount of current imbalance between a supply line and a neutral line of the power conversion device, an amount of power drawn from the output of the power conversion device by an active-row balancing device, or a failure rate of the power conversion circuits.

31. The method of claim 30, wherein the measurement data and trend analysis data is generated internally within the photovoltaic module.

32. The method of claim 30, wherein at least some of the measurement data and trend analysis data is generated by and collected from a loopback device connected to the power conversion device.

33. The method of claim 32, wherein the loop back device comprises one or more of:

a global positioning system device, a voltage calibration device, a current calibration device, an Ethernet port, a wireless communication port, or an illumination calibration device.