Photovoltaic devices with electroplated metal grids

• US 9,502,590 B2
• Filed: 04/19/2016
• Issued: 11/22/2016
• Est. Priority Date: 10/04/2012
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: SolarCity Corporation (Tesla Inc.)
• Inventors: Fu, Jianming, Heng, Jiunn Benjamin, Beitel, Christopher J., Xu, Zheng
• Primary Examiner(s): LEONG, SUSAN DANG
• Application Number:
  US15/132,967
• Publication Number:
  US 20160233354A1
• Time in Patent Office: 217 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 31/0201 comprising specially adapted module bus-bar structures
• CPC Class Codes: H01L 31/022425 for solar cells
• CPC Class Codes: H01L 31/022433 Particular geometry of the grid contacts
• CPC Class Codes: H01L 31/068 the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
• CPC Class Codes: H01L 31/0684 double emitter cells, e.g. bifacial solar cells
• CPC Class Codes: H01L 31/0747 comprising a heterojunction of crystalline and amorphous materials, e.g. heterojunction with intrinsic thin layer
• CPC Class Codes: H01L 31/1804 comprising only elements of Group IV of the Periodic Table
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

One embodiment of the present invention provides a solar cell. The solar cell includes a photovoltaic structure and a front-side metal grid situated above the photovoltaic structure. The front-side metal grid also includes one or more electroplated metal layers. The front-side metal grid includes one or more finger lines, and each end of a respective finger line is coupled to a corresponding end of an adjacent finger line via an additional metal line, thus ensuring that the respective finger line has no open end.

Claims

1. A metallic grid positioned on a photovoltaic structure, the metallic grid comprising:

a first finger line positioned on a first surface of the photovoltaic structure;

a second finger line positioned on the first surface of the photovoltaic structure, wherein the second finger line is substantially parallel to the first finger line; and

a metallic line connecting an end of the first finger line to an adjacent end of the second finger line;

wherein a portion of the first finger line in a vicinity of an intersection between the first finger line and the metallic line is wider than a center portion of the first finger line.

2. The metallic grid of claim 1, wherein the metallic line is wider than at least a portion of the first or second finger line.

3. The metallic grid of claim 1, wherein the intersection between the metallic line and the first finger line is rounded or chamfered.

4. The metallic grid of claim 1, wherein the first finger line comprises a metallic adhesive layer in direct contact with the photovoltaic structure, and wherein the metal adhesive layer comprises at least one of:

Cu, Al, Co, W, Cr, Mo, Ni, Ti, Ta, titanium nitride, titanium tungsten, titanium silicide, titanium silicon nitride, tantalum nitride, tantalum silicon nitride, nickel vanadium, tungsten nitride, or their combinations.

5. The metallic grid of claim 4, wherein the metallic adhesive layer is formed using a physical vapor deposition technique directly onto a transparent conductive oxide layer of the photovoltaic structure.

6. The metallic grid of claim 4, wherein the first finger line further comprises an electroplated metallic layer and a metallic seed layer, wherein the metallic seed layer is positioned between the electroplated metallic layer and the metallic adhesive layer.

7. The metallic grid of claim 1, wherein the first finger line comprises at least one of:

a Cu layer;

an Ag layer;

or

a Sn layer.

8. The metallic grid of claim 1, wherein the portion of the first finger line in the vicinity of the intersection is at least 20% wider than the center portion of the first finger line.

9. The metallic grid of claim 1, wherein a length of the widened portion of the first finger line is between 1 and 30 mm.

10. The metallic grid of claim 1, wherein a width of the intersection is 0.2 mm or less.

11. A metal grid on a surface of a photovoltaic structure, the grid comprising:

a busbar positioned on the surface of the photovoltaic structure;

a first finger line on the surface of the photovoltaic structure and substantially orthogonal to the busbar;

a second finger line on the surface of the photovoltaic structure and substantially orthogonal to the busbar;

a third finger line on the surface of the photovoltaic structure and substantially orthogonal to the busbar; and

a connecting metal line, wherein the connecting metal line electrically connects the first, second and the third finger lines, and wherein a portion of the first finger line in a vicinity of an intersection between the first finger line and the connecting metal line is wider than a center portion of the first finger line.

12. The metal grid of claim 11, wherein the connecting metal line is wider than at least a portion of the first finger line.

13. The metal grid of claim 11, wherein the intersection between the connecting metal line and the first finger line is rounded or chamfered.

14. The metal grid of claim 11, wherein the first finger line comprises at least one of:

a Cu layer;

an Ag layer;

or

a Sn layer.

15. The metal grid of claim 11, wherein the first finger line comprises a metallic adhesive layer in direct contact with the photovoltaic structure, and wherein the metal adhesive layer comprises at least one of:

Cu, Al, Co, W, Cr, Mo, Ni, Ti, Ta, titanium nitride, titanium tungsten, titanium silicide, titanium silicon nitride, tantalum nitride, tantalum silicon nitride, nickel vanadium, tungsten nitride, or their combinations.

16. The metal grid of claim 15, wherein the metallic adhesive layer is formed using a physical vapor deposition technique directly onto a transparent conductive oxide layer of the photovoltaic structure.

17. The metal grid of claim 15, wherein the first finger line further comprises an electroplated metallic layer and a metallic seed layer, wherein the metallic seed layer is positioned between the electroplated metallic layer and the metallic adhesive layer.

18. The metal grid of claim 11, wherein the portion of the first finger line in the vicinity of the intersection is at least 20% wider than the center portion of the first finger line.

19. The metal grid of claim 11, wherein a length of the widened portion of the first finger line is between 1 and 30 mm.

20. The metal grid of claim 11, wherein a width of the intersection is 0.2 mm or less.