# US 2014/0196768 A1 · Module fabrication of solar cells with low resistivity electrodes

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- Number: US 2014/0196768 A1
- Document ID: US20140196768A1
- Status: Published application
- Kind: A1
- Application number: 14/153,608
- Filed: 2014-01-13
- Published: 2014-07-17
- Earliest claimed: 2013-01-11
- Assignees: SolarCity Corporation
- Applicants: Silevo, Inc.
- Inventors: Jiunn Benjamin Heng; Jianming Fu; Zheng Xu; Bobby Yang
- Web page: https://patentgrep.com/patent/US20140196768A1

## CPC

- H10F 77/937: {Busbar structures for modules}
- H10F 10/148: {Double-emitter photovoltaic cells, e.g. bifacial photovoltaic cells}
- H10F 10/166: the Group IV-IV heterojunctions being heterojunctions of crystalline and amorphous materials, e.g. silicon heterojunction [SHJ] photovoltaic cells
- H10F 19/80: Encapsulations or containers for integrated devices, or assemblies of multiple devices, having photovoltaic cells
- H10F 19/807: {Double-glass encapsulation, e.g. photovoltaic cells arranged between front and rear glass sheets}
- H10F 19/902: {for series or parallel connection of photovoltaic cells}
- H10F 71/137: {Batch treatment of the devices}
- H10F 77/211: {for photovoltaic cells}
- H10F 77/215: {Geometries of grid contacts}
- H10F 77/955: {for photovoltaic devices}
- Y02E 10/547: Monocrystalline silicon PV cells
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## 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

### Claim 1

A solar cell, comprising:
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, wherein the front-side and the back-side electrodes each comprises a metal grid, wherein a respective metal grid comprises a plurality of finger lines and a single busbar coupled to the finger lines, and wherein the single busbar is configured to collect current from the finger lines.

### Claim 2 (depends on 1)

The solar cell of claim 1, wherein the single busbar is located at a center of a respective surface of the solar cell.

### Claim 3 (depends on 1)

The solar cell of claim 1, wherein the single busbar is located at an edge of a respective surface of the solar cell.

### Claim 4 (depends on 3)

The solar cell of claim 3, wherein a first single busbar at a front surface of the solar cell and a second single busbar at a back surface of the solar cell are located at opposite edges.

### Claim 5 (depends on 1)

The solar cell of claim 1, wherein the multi-layer semiconductor structure comprises:
a base layer;
a front- or back-side emitter; and
a back or front surface field layer.

### Claim 6 (depends on 5)

The solar cell of claim 5, wherein the multi-layer semiconductor structure further comprises a quantum tunneling barrier (QTB) layer situated at both sides of the base layer

### Claim 7 (depends on 1)

The solar cell of claim 1, wherein the metal grid comprises at least an electroplated Cu layer.

### Claim 8 (depends on 1)

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

### Claim 9

A solar module, comprising:
a front-side cover;
a back-side cover; and
a plurality of solar cells situated between the front- and back-side covers, wherein a respective solar cell comprises:
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, wherein the front-side and the back-side electrodes each comprises a metal grid, wherein a respective metal grid comprises a plurality of finger lines and a single busbar coupled to the finger lines, and wherein the single busbar is configured to collect current from the finger lines.

### Claim 10 (depends on 9)

The solar module of claim 9, wherein the single busbar is located at a center of a respective surface of the solar cell.

### Claim 11 (depends on 10)

The solar module of claim 10, wherein two adjacent solar cells are strung together by a stringing ribbon weaved from a front surface of a solar cell and to a back surface of an adjacent solar cell, wherein the stringing ribbon is soldered to single busbars on the front and the back surfaces, and wherein a width of the stringing ribbon is substantially similar to a width of the single busbar.

### Claim 12 (depends on 9)

The solar module of claim 9, wherein single busbars of a front and a back surface of the solar cell are located at opposite edges.

### Claim 13 (depends on 12)

The solar module of claim 12, wherein two adjacent solar cells are coupled together by a metal tab soldered to a first single busbar at an edge of a solar cell and a second single busbar at an adjacent edge of the adjacent solar cell, wherein a width of the metal tab is substantially similar to a length of the first and the second single busbar.

### Claim 14 (depends on 13)

The solar module of claim 13, wherein a length of the metal tab is between 3 and 12 mm.

### Claim 15 (depends on 9)

The solar module of claim 9, wherein the multi-layer semiconductor structure comprises:
a base layer;
a front- or back-side emitter; and
a back or front surface field layer.

### Claim 16 (depends on 15)

The solar module of claim 15, wherein the multi-layer semiconductor structure comprises a quantum tunneling barrier (QTB) layer situated at both sides of the base layer.

### Claim 17 (depends on 9)

The solar module of claim 9, wherein the metal grid comprises at least an electroplated Cu layer.

### Claim 18 (depends on 9)

The solar module of claim 9, wherein a width of the single busbar is between 0.5 and 3 mm.

### Claim 19 (depends on 9)

The solar module of claim 9, further comprising a plurality of maximum power point tracking (MPPT) devices, wherein a respective MPPT device is coupled to an individual solar cell, thereby facilitating cell-level MPPT.

### Claim 20 (depends on 9)

The solar module of claim 9, wherein the front-side and the back-side covers are transparent to facilitate bifacial configuration of the solar module.