Flat-plate photovoltaic module

• US 8,748,727 B2
• Filed: 01/21/2009
• Issued: 06/10/2014
• Est. Priority Date: 01/18/2008
• Status: Active Grant

• Current Assignee: Spectrum Solar, LLC
• Original Assignee: Tenksolar, Inc.
• Inventors: Meyer, Dallas W.
• Primary Examiner(s): Ridley, Basia
• Assistant Examiner(s): Chern, Christina
• Application Number:
  US12/357,268
• Publication Number:
  US 20090183763A1
• Time in Patent Office: 1,966 Days
• Field of Search: 136243-246, 136/251, 136/293
• US Class Current: 136/244
• CPC Class Codes: H01L 31/02021 for solar cells electrical connection means, e.g. junction boxes, specially adapted for structural association with photovoltaic modules H02S40/34
• CPC Class Codes: H02S 40/32 comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

One example embodiment includes a PV module comprising a conductive backsheet, a non-conductive layer disposed on the conductive backsheet, a plurality of PV cells arranged in rows and collectively generating a first power output characterized by a first voltage, and a power conversion device. Each of the rows can include two or more PV cells. The PV cells within each row can be connected to each other in parallel. The rows can be connected in series. A top row can be connected to the conductive backsheet. The power conversion device can be redundantly connected to a bottom row and to the conductive backsheet to form a complete circuit. The power conversion device can convert the first power output to a second power output characterized by a second voltage that is larger than the first voltage. The power conversion device can also maintain peak power of the PV cells.

Claims

1. A photovoltaic module, comprising:

a conductive backsheet extending continuously and uninterrupted behind all of a plurality of photovoltaic cells of the photovoltaic module;

a non-conductive layer disposed on the conductive backsheet;

the plurality of photovoltaic cells disposed above the non-conductive layer, the plurality of photovoltaic cells arranged in a plurality of rows and collectively generating a first power output characterized by a first voltage, wherein;

each row includes two or more photovoltaic cells;

the photovoltaic cells within each row are connected to each other in parallel;

the plurality of rows are connected in series; and

a top row is connected to the conductive backsheet;

a power conversion device redundantly connected to a bottom row of the plurality of rows and to the conductive backsheet to form a complete circuit, the power conversion device maintaining a composite electrical impedance of a plurality of power conversion circuits of the power conversion device to ensure the plurality of photovoltaic cells in the photovoltaic module are operating at maximum peak power such that a second voltage from the power conversion device is higher than the first voltage generated by the plurality of photovoltaic cells; and

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

the power conversion device includes a printed circuit board mounted along an edge of the photovoltaic module, the printed circuit board including a larger planar surface and a different smaller planar surface, wherein the larger planar surface of the printed circuit board is substantially normal to a plane defined by the conductive backsheet;

the plurality of rows are connected in series via the plurality of conductive spacers;

at least a portion of a bottom conductive spacer extends beyond a corresponding edge of the conductive backsheet, the bottom conductive spacer being coupled between the power conversion device and the bottom row;

the photovoltaic module further comprises a first stress-relief fold formed in the conductive backsheet and a second stress-relief fold formed in the bottom conductive spacer; and

the first stress-relief fold interconnects the conductive backsheet to the power conversion device and the second stress-relief fold interconnects the power conversion device in series with the plurality of rows.

2. The photovoltaic module of claim 1, wherein a voltage generated across the plurality of photovoltaic cells from the top row to the bottom row is less than or equal to 10 volts.

3. The photovoltaic module of claim 1, wherein the plurality of photovoltaic cells are sealed within a protective enclosure to prevent exposure of the plurality of photovoltaic cells to moisture, the protective enclosure comprising the conductive backsheet, a solar edge tape, and a front plate disposed above the plurality of photovoltaic cells.

4. The photovoltaic module of claim 1, wherein the conductive backsheet comprises electrical ground for the plurality of photovoltaic cells and the power conversion device.

5. The photovoltaic module of claim 1, wherein:

at least some of the heat generated by the plurality of photovoltaic cells is conductively transferred to the conductive backsheet; and

the conductive backsheet radiates at least some of the heat conductively transferred to the conductive backsheet away from the photovoltaic module.

6. The photovoltaic module of claim 1, wherein the power conversion device comprises two complementary connectors disposed on opposite ends of the power conversion device, the two complementary connectors allowing the photovoltaic module and power conversion device to be connected side-to-side to one or more similarly configured photovoltaic modules and power conversion devices.

7. The photovoltaic module of claim 1, wherein the power conversion device includes a ground terminal post and a positive terminal post, each configured to receive a different conductive wire having a cross-sectional area greater than 3 mm², the different conductive wires transmitting the second power output to a point of use.

8. The photovoltaic module of claim 1, wherein the second voltage is less than or equal to 60 volts, the photovoltaic module further comprising an active ground fault detection device that identifies interrupts in the second power output and limits energy flow out of the photovoltaic module to less than 24 joules after identifying an interrupt.

9. The photovoltaic module of claim 8, wherein the conductive backsheet comprises an exposed electrical ground and the non-conductive layer is less than 10 mils thick.

10. The photovoltaic module of claim 1, wherein:

at least some heat generated by the plurality of photovoltaic cells during operation is conductively transferred to the conductive backsheet, whereupon the back of the conductive backsheet radiates at least some of the heat away from the back of the photovoltaic module;

or

the conductive backsheet generates heat in response to absorbing light rays incident on the back of the conductive backsheet, at least some of the heat is conductively transferred to the plurality of photovoltaic cells, and the photovoltaic cells radiate heat away from the front of the photovoltaic module to melt ice or snow that has accumulated on the front of the photovoltaic module.

11. The photovoltaic module of claim 1, wherein the photovoltaic module is mounted to a wall structure and receives solar radiation directly from the sun or indirectly via reflection from one or more reflective materials disposed in, on or proximate to the wall structure, the received solar radiation being non-uniform in intensity across the front of the photovoltaic module.

12. The photovoltaic module of claim 11, wherein the one or more reflective materials comprise a window disposed in the wall structure.

13. The photovoltaic module of claim 1, wherein the plurality of rows are arranged side-by-side and the plurality of conductive spacers are disposed between the plurality of rows and the non-conductive layer to maximize photovoltaic cell density on a front side of the photovoltaic module.

15. The photovoltaic module of claim 1, wherein each of the plurality of conductive spacers comprises solid copper, patterned copper, solid aluminum, or patterned aluminum.

16. The photovoltaic module of claim 1, wherein each of the plurality of photovoltaic cells is substantially rectangular or substantially trapezoidal in shape, further wherein each photovoltaic cell in each of the plurality of rows is connected to two conductive spacers between which each of the plurality of rows is interconnected.

17. 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.

18. The photovoltaic module of claim 17, wherein the power conversion device draws operating power from the first power output and the active row-balancing device draws operating power from the second power output.

19. The photovoltaic module of claim 17, wherein one or both of the power conversion device and the active row-balancing device include a printed circuit board having a length-to-width aspect ratio greater than or equal to 20:

1 and less than or equal to 40;

1.

20. The photovoltaic module of claim 17, wherein one or both of the power conversion device and the active row-balancing device comprise consumer electronics.

21. The photovoltaic module of claim 17, wherein the active row-balancing device includes a plurality of active electronic devices, each of the plurality of active electronic devices comprising one or more of:

a field effect transistor, a gate driver, an inductor, a capacitor, or a microcontroller.

22. The photovoltaic module of claim 21, wherein each of the plurality of active electronic devices is coupled in parallel with a corresponding one of the plurality of rows, each of the plurality of active electronic devices feeding current into the corresponding one of the plurality of rows when the corresponding one of the plurality of rows is blocked.

14. The photovoltaic module of 1, further comprising a plurality of bypass diodes coupled in series with each other via the plurality of conductive spacers, each bypass diode connected in anti-parallel with a different row such that when a row is blocked, current can flow around the row through the corresponding bypass diode coupled in anti-parallel with the blocked row.

23. A photovoltaic system, comprising:

a photovoltaic module including;

a conductive backsheet extending continuously and uninterrupted behind all of a plurality of photovoltaic cells of the photovoltaic module;

a substantially transparent front plate;

the 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 interposed between the photovoltaic cells, the conductive spacers including a top spacer and a bottom spacer, the top spacer interconnecting a top row to the conductive backsheet; and

a power conversion device redundantly connected to a bottom row via the bottom spacer and to the conductive backsheet to form a complete circuit, the power conversion device maintaining a composite electrical impedance of a plurality of power conversion circuits of the power conversion device to ensure the plurality of photovoltaic cells in the photovoltaic module are operating at maximum peak power such that a second voltage from the power conversion device is higher than the first voltage generated by the plurality of photovoltaic cells,

wherein the power conversion device includes a printed circuit board mounted along an edge of the photovoltaic module, the printed circuit board includes a larger planar surface and a different smaller planar surface, and the larger planar surface of the printed circuit board is substantially normal to a plane defined by the conductive backsheet; and

a plurality of louvers positioned above the conductive spacers and the front plate, the louvers reflecting solar radiation incident on the louvers onto the photovoltaic cells, wherein;

the plurality of rows are connected in series via the plurality of conductive spacers;

at least a portion of the bottom conductive spacer extends beyond a corresponding edge of the conductive backsheet;

the photovoltaic module further comprises a first stress-relief fold formed in the conductive backsheet and a second stress-relief fold formed in the bottom conductive spacer; and

the first stress-relief fold interconnects the conductive backsheet to the power conversion device and the second stress-relief fold interconnects the power conversion device in series with the plurality of rows.

24. The photovoltaic system of claim 23, wherein each of the louvers includes a base, the photovoltaic system further comprising a separation layer disposed between the front plate and the base of the louvers.

25. The photovoltaic system of claim 23, wherein each of the louvers comprises a thermally conductive material and facilitates cooling of the photovoltaic module.