Module fabrication of solar cells with low resistivity electrodes

• US 9,412,884 B2
• Filed: 10/08/2014
• Issued: 08/09/2016
• Est. Priority Date: 01/11/2013
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: SolarCity Corporation (Tesla Inc.)
• Inventors: Heng, Jiunn Benjamin, Fu, Jianming, Xu, Zheng, Yang, Bobby
• Primary Examiner(s): LEONG, SUSAN DANG
• Application Number:
  US14/510,008
• Publication Number:
  US 20150270410A1
• Time in Patent Office: 671 Days
• Field of Search: 136/252, 136/256
• US Class Current: 1/1
• CPC Class Codes: H01L 31/0201 comprising specially adapted module bus-bar structures
• CPC Class Codes: H01L 31/0504 specially adapted for series or parallel connection of solar cells in a module
• 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: H02S 40/30 Electrical components
• CPC Class Codes: H02S 40/36 characterised by special electrical interconnection means between two or more PV modules, e.g. electrical module-to-module connection
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells

Abstract

One embodiment of the present invention provides a solar module. The solar module includes a front-side cover, a back-side cover, and a plurality of solar cells situated between the front- and back-side covers. A respective solar cell includes a multi-layer semiconductor structure, a front-side electrode situated above the multi-layer semiconductor structure, and a back-side electrode situated below the multi-layer semiconductor structure. Each of the front-side and the back-side electrodes comprises a metal grid. A respective metal grid comprises a plurality of finger lines and a single busbar coupled to the finger lines. The single busbar is configured to collect current from the finger lines.

Claims

1. A solar module, comprising:

a plurality of connected solar cells, wherein a respective solar cell comprises;

a multi-layer semiconductor structure that has a first-polarity surface and a second-polarity surface, wherein the second polarity is opposite to the first polarity;

a first electrode on the first-polarity surface; and

a second electrode on the second-polarity surface;

wherein the first and second electrodes each comprise a plurality of finger lines and a busbar coupled to the finger lines; and

wherein the first-polarity surface and second-polarity surface each have only an area near one edge covered by the busbar.

2. The solar module of claim 1, wherein two adjacent solar cells are connected to each other by a stringing ribbon soldered to a first busbar on the first-polarity surface of a first solar cell and a second busbar on the second-polarity surface of an adjacent solar cell, and wherein a width of the stringing ribbon is substantially similar to a width of the busbars.

3. The solar module of claim 1, wherein the busbars on the first-polarity surface and second-polarity surface of the solar cell are located near opposite edges.

4. The solar module of claim 3, wherein two adjacent solar cells are connected by a metal tab soldered to a first busbar on the first-polarity surface of a first solar cell and a second busbar on the second-polarity surface of the adjacent solar cell, wherein a width of the metal tab is substantially similar to a length of the first and second busbars.

5. The solar module of claim 4, wherein the first-polarity surface of the first solar cell and the second-polarity surface of the adjacent solar cell are facing different directions.

6. The solar module of claim 4, wherein the first-polarity surface of the first solar cell and the second-polarity surface of the adjacent solar cell are facing a same direction.

7. The solar module of claim 4, wherein a plurality of solar cells are coupled by metal tabs into a string, and wherein a plurality of strings are coupled electrically in series or in parallel.

8. The solar module of claim 4, wherein a length of the metal tab is between 3 and 12 mm.

9. The solar module of claim 3, wherein two adjacent solar cells are coupled together by overlapping edges of the two adjacent solar cells, wherein the two adjacent solar cells are overlapped in such a way that a first busbar on the first-polarity surface of a first solar cell is in contact with a second busbar on the second-polarity surface of an adjacent solar cell, thereby facilitating a serial connection between the two adjacent solar cells.

10. The solar module of claim 9, wherein a plurality of solar cells are coupled by overlapping edges to form a string, and wherein a plurality of strings are coupled electrically in series or in parallel.

11. The solar module of claim 1, wherein the multi-layer semiconductor structure comprises:

a base layer;

a front- or back-side emitter layer; and

a back or front surface field layer.

12. The solar module of claim 11, wherein the multi-layer semiconductor structure comprises a quantum tunneling barrier (QTB) layer positioned at both sides of the base layer.

13. The solar module of claim 1, wherein the first and second electrodes each comprise at least an electroplated Cu layer.

14. The solar module of claim 1, wherein a width of the busbar is between 0.5 and 3 mm.

15. The solar module of claim 1, further comprising a plurality of maximum power point tracking devices, wherein a respective maximum power point tracking device is coupled to an individual solar cell, thereby facilitating cell-level maximum power point tracking.

16. The solar module of claim 1, further comprising a plurality of maximum power point tracking devices, wherein a respective maximum power point tracking device is coupled to a string of solar cells, thereby facilitating string-level maximum power point tracking.

17. The solar module of claim 1, further comprising a front-side cover and a back-side cover, wherein both the front- and back-side covers are transparent to facilitate bifacial configuration of the solar module.

18. The solar module of claim 1, wherein the plurality of solar cells includes at least one of:

a 5-inch solar cell;

a 6-inch solar cell; and

a ⅛

, ⅙

, ¼

, ⅓

, or ½

of a 5-inch or a 6-inch solar cell.

19. A solar cell coupling system, comprising:

a first solar cell and a second solar cell, wherein a respective solar cell comprises a first electrode on a first-polarity surface and a second electrode on a second-polarity surface, wherein a respective electrode comprises a plurality of finger lines and a busbar coupled to the finger lines, the busbar being positioned near an edge of the respective solar cell, and wherein the first-polarity surface and second-polarity surface each have only an area covered by the busbar; and

a metal tab connecting the first electrode of the first solar cell and the second electrode of the second solar cell.

20. A solar cell coupling system, comprising:

a first solar cell and a second solar cell connected to each other, wherein a respective solar cell comprises a first electrode on a first-polarity surface and a second electrode on a second-polarity surface, wherein a respective electrode comprises a plurality of finger lines and a busbar coupled to the finger lines, the busbar being positioned near an edge of the respective solar cell, and wherein the first-polarity surface and second-polarity surface each have only an area covered by the busbar;

wherein an edge of the first solar cell overlaps with an edge of the second solar cell such that busbar on the first-polarity surface of the first solar cell is in contact with a busbar on the second-polarity surface of the second solar cell.