INTERDIGITATED FOIL INTERCONNECT FOR REAR-CONTACT SOLAR CELLS

• US 20130112233A1
• Filed: 10/29/2012
• Published: 05/09/2013
• Est. Priority Date: 10/31/2011
• Status: Active Grant

• Current Assignee: Cellink Corporation
• Original Assignee: Cellink Corporation
• Inventors: Coakley, Kevin Michael
• Granted Patent: US 10,383,207 B2
• Time in Patent Office: Days
• US Class Current: 136/244
• CPC Class Codes: H01L 31/049 Protective back sheets
• CPC Class Codes: H01L 31/0516 specially adapted for interconnection of back-contact solar cells
• CPC Class Codes: H05K 1/02 Details
• CPC Class Codes: H05K 1/113 Via provided in pad; Pad over filled via
• CPC Class Codes: H05K 1/189 characterised by the use of a flexible or folded printed circuit H05K3/326 takes precedence
• CPC Class Codes: H05K 2201/10143 Solar cell
• CPC Class Codes: H05K 2203/033 Punching metal foil, e.g. solder foil
• CPC Class Codes: H05K 2203/175 Configurations of connections suitable for easy deletion, e.g. modifiable circuits or temporary conductors for electroplating; Processes for deleting connections
• CPC Class Codes: H05K 3/202 using self-supporting metal foil pattern
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor

Abstract

Layers of conductive foil and insulating material are configured to interconnect an array of rear-contact solar cells. An embodiment provides that the layer of conductive foil may be patterned to form repeating sets of electrically isolated, interdigitated fingers. Each set of interdigitated fingers may be used to connect the positive polarity contacts of a first rear-contact solar cell to the negative polarity contacts of a second, adjacent rear-contact cell. The insulating layer is attached to the patterned conductive foil and provides mechanical support and/or electrical isolation. In some embodiments, a protective backsheet may be disposed beneath the conductive foil and/or insulating layer to provide further mechanical support and environmental protection. In some embodiments, the layers of conductive foil and insulating material may be incorporated as an interconnect circuit in a rear-contact PV module.

Claims

1. A conductive backsheet comprising:

a protective backsheet;

an insulating layer; and

a patterned conductive foil comprising interdigitated fingers;

wherein;

the patterned conductive foil is attached to and is mechanically supported by the insulating layer.

2. The conductive backsheet of claim 1, wherein the insulating layer is disposed beneath the conductive foil and above the protective backsheet.

3. The conductive backsheet of claim 1, wherein the conductive foil is disposed above the protective backsheet and beneath the insulating layer, and the insulating layer comprises openings that at least partially match the pattern of contacts of a rear-contact solar cell.

4. The conductive backsheet of claim 3, wherein the protective backsheet further comprises a top adhesive layer.

5. The conductive backsheet of claim 4, wherein the top adhesive layer thickness is at least 50% of the thickness of the conductive foil.

6. The conductive backsheet of claim 5, wherein the top adhesive layer at least partially occupies the openings or gaps in the patterned conductive foil.

7. The conductive backsheet of claim 4, wherein a tie layer is disposed between the conductive foil and the top adhesive layer of the protective backsheet.

8. The conductive backsheet of claim 2 or 3, wherein the insulating layer does not extend all the way to the edge of the protective backsheet.

9. The conductive backsheet of claim 8, wherein the width of the insulating layer is within 20% of the width of a rear-contact solar cell.

10. The conductive backsheet of claim 8, wherein the width of the insulating layer is within 20% of the combined width of two rear-contact solar cells.

11. The conductive backsheet of claim 8, wherein the width of the insulating layer is within 20% of the width of a rear-contact PV module.

12. The conductive backsheet of claim 2, wherein a connecting busbar is disposed beneath the insulating layer and above the protective backsheet, and is electrically connected to the conductive foil through the insulating layer.

13. The conductive backsheet of claim 3, wherein a connecting busbar is disposed beneath the patterned conductive foil and above the protective backsheet, and is electrically connected to the conductive foil.

14. The conductive backsheet of claim 3, wherein a second adhesive layer is disposed above the insulating layer, and wherein the second adhesive layer comprises openings that at least partially overlap the openings in the insulating layer.

15. The conductive backsheet of claim 14, wherein the second adhesive layer is less than approximately 100 microns thick.

16. The conductive backsheet of claim 14, wherein the second adhesive layer is less than approximately 50 microns thick.

17. The conductive backsheet of claim 2 or 3, wherein the patterned conductive foil comprises aluminum.

18. The conductive backsheet of claim 17, wherein the aluminum is coated with a surface finish selected from the group:

zinc, silver, copper, nickel, chrome, or gold.

19. The conductive backsheet of claim 17, wherein the second adhesive layer has a melt flow index of less than approximately 8 dg/min.

20. The conductive backsheet of claim 17, wherein the second adhesive layer has a melt flow index of less than approximately 4 dg/min.

21. The conductive backsheet of claim 18, wherein the conductive backsheet has been further incorporated into a rear-contact PV module, and wherein the rear-contact PV module comprises an electrically conductive adhesive material containing a corrosion inhibitor.

22. The conductive backsheet of claim 1, wherein the insulating layer comprises openings that at least partially overlap openings in the patterned conductive foil.

23. The conductive backsheet of claim 1, wherein a patterned adhesive layer is disposed between the insulating layer and the patterned conductive foil.

24. The conductive backsheet of claim 22 or 23, wherein the insulating layer is less than approximately 50 microns thick.

25. The conductive backsheet of claim 22 or 23, wherein the pattern of interdigitated fingers has a periodicity of approximately 3 cm or less.

26. A method of fabricating an interconnect circuit comprising:

in a first removal step, forming a pattern of discontinuous openings in a conductive foil;

laminating the conductive foil to a mechanically supportive insulating layer; and

in a second removal step, removing the remaining undesired portions of conductive foil to form mechanically supported, electrically isolated sets of interdigitated fingers.

27. A method of fabricating an interconnect circuit comprising:

in a first lamination step, laminating a conductive foil to a temporary carrier substrate comprising a low-tack adhesive;

kiss cutting a pattern of interdigitated fingers into the conductive foil;

forming a high-tack patterned adhesive layer on an insulating layer, wherein the pattern in the adhesive layer at least partially matches the pattern of interdigitated fingers in the conductive foil;

in a second lamination step, laminating the exposed surface of the conductive foil to the insulating layer via the patterned adhesive layer, wherein the patterned adhesive layer is aligned with the kiss cut pattern of interdigitated fingers; and

peeling away the temporary carrier substrate and undesired regions of conductive foil.