Back contact solar cell and cell assembly

Abstract

The utility model discloses a back contact solar cell and a cell assembly, comprising grid lines, a plurality of grid lines extending along a first direction and provided with discontinuous regions along a second direction, the discontinuous regions of two adjacent grid lines are staggered, the grid lines are provided with reinforcing portions with increased widths, and the reinforcing portions and the discontinuous regions are at least partially collinear in the second direction. By arranging the reinforcing part with the increased width, the contact area between the grid line and the conductive wire or the welding strip can be increased, and the connection strength and the connection quality are improved; and the discontinuous region is arranged, so that physical isolation is formed between the conductive wire and the grid line which are opposite in polarity, and insulating glue is avoided.

Description

Technical Field

[0001] The utility model relates to a back-contact solar cell sheet and a battery assembly, belonging to the technical field of photovoltaics. Background Art

[0002] Back-contact solar cells have broad application prospects due to their higher photoelectric conversion efficiency. Back-contact solar cells are cells in which both the emitter and base contact electrodes are placed on the back side (non-light-receiving side) of the cell. This leaves the light-receiving side unobstructed by any metal electrodes, effectively increasing the short-circuit current of the cell.

[0003] like Figure 1 The figure shows a prior art design for a back-contact solar cell. To achieve convergence of the positive electrode and fine grids of the same polarity, conductive glue is typically printed at corresponding locations on the grid lines of the same polarity to improve weldability with the conductive wires / welding strips, allowing for welded contact between the conductive wires / welding strips and the grid lines of the same polarity. Insulating glue is then printed at corresponding locations on the grid lines of opposite polarity to insulate them from the conductive wires / welding strips, thereby achieving convergence of fine grids of different polarities. To ensure good insulation, the insulating glue is generally printed at a height of over 20μm. To avoid wire breakage, the conductive glue needs to be printed at a higher height, resulting in higher conductive glue consumption, which further increases costs. Furthermore, high insulating glue printing consumption can easily cause cell bending, increasing the risk of hidden cracks and fragmentation.

[0004] The invention patent application, publication number CN 115579407 A, discloses an electrode structure and a back-contact solar cell. On the back of the cell, a first grid line and a second grid line are arranged in a first direction. The first and second grid lines carry currents of opposite polarity and are alternately arranged in a second direction. A busbar connects the first grid line or the second grid line along the second direction. When the busbar connects the first grid line along the second direction, the second grid line is disconnected on both sides of the busbar. The busbar located between the first grid line or the second grid line has at least one widened portion. This structure requires strict alignment of the widened busbar portion and the disconnected grid line portion during cell assembly, otherwise a short circuit can easily occur. Utility Model Content

[0005] Purpose of the utility model: The purpose of the utility model is to provide a back-contact solar cell that ensures the connection strength between the conductive wires and the back grid lines and is easy to process; another purpose of the utility model is to provide a battery assembly.

[0006] Technical solution: The back-contact solar cell described in the present invention includes grid lines, several of which extend along a first direction and are provided with a discontinuity region along a second direction, the discontinuity regions of two adjacent grid lines are staggered, and the grid lines are provided with a reinforcement portion with increased width, and in the second direction, the reinforcement portion and the discontinuity region are at least partially collinear.

[0007] Preferably, the reinforcement is co-linear with the discontinuity.

[0008] Preferably, the reinforcement portion is located in the middle and / or at the end of the grid line.

[0009] Preferably, in order to avoid short circuit during assembly, in the second direction, the distance between the reinforcement portion and the adjacent gate line is 0.2-5 mm.

[0010] Preferably, in order to avoid short circuit caused by deviation of the conductive line, the thickness of the reinforcement portion is not less than the thickness of the gate line.

[0011] A battery assembly is formed by assembling the aforementioned back-contact solar cell sheet and a conductive wire, wherein the conductive wire passes through the discontinuous area and is conductively connected to the reinforcement part.

[0012] Preferably, the conductive wire is a strip-shaped conductive wire.

[0013] Preferably, in order to reduce thermal deformation of the battery assembly, the conductive wire is a welding strip with a conductive coating.

[0014] Preferably, both ends of the conductive line are connected to the reinforcement parts of the two battery cells respectively, and the currents guided by the reinforcement parts at both ends of the conductive line have opposite polarities.

[0015] Beneficial effects: Compared with the prior art, the utility model has the following advantages: 1. Improved connection strength and easy processing: the enhanced portion with increased width can increase the contact area between the gate line and the conductive wire or the welding strip, improve the connection strength and connection quality. During assembly, the connection can be completed using a long strip of conductive wire without calibration; 2. Effectively prevent short circuits caused by misalignment; 3. Eliminate the need for insulating glue: when the conductive wire is connected to the gate line enhancement portion of one polarity, the discontinuity area is used to form physical isolation with the gate line of the other polarity. No insulating glue needs to be printed during the processing, which simplifies the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the grid line structure of a back-contact solar cell in the prior art;

[0017] Figure 2 This is a schematic diagram of the grid line structure of the back contact solar cell of the present invention;

[0018] Figure 3 This is a schematic diagram of the battery assembly structure of the present utility model. DETAILED DESCRIPTION

[0019] The technical solution of the present utility model will be further described below with reference to the accompanying drawings.

[0020] Example 1: See Figure 2 、 Figure 3 This embodiment provides a back-contact solar cell. The cell mainly consists of a silicon substrate, and doped layers and doped regions formed on the silicon substrate. The doped layers and doped regions extend continuously along a first direction in a strip shape and are alternately arranged along a second direction. In the second direction, two adjacent doped layers (or doped regions) may be connected or not connected. The cell is based on existing technology and will not be described in detail.

[0021] The back of the cell is provided with first and second gate lines 1 and 2 extending along a first direction. These first and second gate lines 1 and 2 are electrode lines used to conduct the cell current. Corresponding to the doped layers and doped regions, the first and second gate lines 1 and 2 are arranged alternately and parallel in a second direction. That is, the first and second gate lines 1 and 2 are located on the doped layers and doped regions on the silicon substrate, respectively, and the currents conducted by the first and second gate lines 1 and 2 have opposite polarities. In the first direction, the first and second gate lines 1 and 2 each have several discontinuities. In the second direction, the discontinuities of adjacent first and second gate lines 1 and 2 are staggered.

[0022] Reinforcement portions are provided on first gate line 1 and second gate line 2, respectively. Reinforcement portion 12 is wider than remaining portion 11 of first gate line 1, and reinforcement portion 22 is wider than remaining portion 21 of second gate line 2. The reinforcement portions are used to increase the contact area between the gate line and the conductive wire or soldering strip, improving the connection strength and quality.

[0023] In the second direction, the reinforcement portion 12 of the first gate line 1 and the discontinuity region of the adjacent second gate line 2 are at least partially collinear. Similarly, the reinforcement portion 22 of the second gate line 1 and the discontinuity region of the adjacent first gate line 1 are at least partially collinear.

[0024] In the second direction, the reinforcement portion 12 of the first gate line 1 is spaced apart from the adjacent second gate line 2 by a distance D, and the reinforcement portion 22 of the second gate line 2 is spaced apart from the adjacent first gate line 1 by a distance D = 0.2-5 mm to avoid short circuit during conductive connection.

[0025] In the second direction, the size of the enhancement parts 12 and 22 is smaller than the width of the underlying doped region or doped layer, so that no additional process or repeated laser scanning is required to form the underlying doped region or doped layer below the enhancement parts.

[0026] The reinforcing portion 12, 22 can be formed into the electrode grid line pattern with the reinforcing portion by disposable printing through the design of the printing screen, and can also be formed by secondary printing, that is, first printing to form thin grid lines, and then secondary printing the reinforcing portion pattern. In the case of secondary printing, the thickness of the reinforcing portion 12, 22 can be greater than the grid line remainder 11, 21, so that when the conductive line is electrically connected to the reinforcing portion 12, 22, even if the conductive line locally deviates, it will not contact with the adjacent first grid line 1 or the second grid line 2. The reinforcing portion can be a rectangular shape, or it can be other arbitrary shapes, such as circle, ellipse, rhombus, hexagon, etc., which are not limited to this. The reinforcing portion can be located in the middle of the grid line, or it can be located at the end.

[0027] Example 2: In the second direction, the enhancement portion 22 provided on the second gate line 2 is exactly located in the discontinuous area between two adjacent segments of the first gate line 1, that is, the enhancement portion and the discontinuous area are collinear. Similarly, the enhancement portion 12 provided on the first gate line 1 is exactly located in the discontinuous area between two adjacent segments of the second gate line 2.

[0028] Example 3: See Figure 3 , is a schematic diagram of the structure of a battery assembly formed by assembling the battery cells in Example 2.

[0029] From left to right in the figure, the three cells are the first cell, the second cell, and the third cell. The directions of two adjacent cells are opposite, that is, when the top of the first cell is the first grid line 1, the top of the second cell is the second grid line 2.

[0030] The main portion of the left half of the conductive wire 5 is located on the reinforcement portion 12 of the first grid line 1 of the first cell, while passing through the discontinuity of the second grid line 2, connecting the first grid line 1 of the first cell in series. Thus, when the left half of the conductive wire 5 is conductively interconnected with the first grid line 1, it is only conductively connected to the electrode grid line of one polarity and is physically isolated from the second grid line 2 of the other polarity, eliminating the need for printed insulating adhesive. Similarly, the right half connects the second grid line 2 of the second cell in series. The relatively large area of the reinforcement portion helps improve the quality and reliability of the connection between the conductive wire 5 and the grid line.

[0031] The connection between the conductive wire 5 and the first gate line 1 or the second gate line 2 is a conventional connection or a low-temperature connection. In the low-temperature connection mode, the conductive wire is in direct contact with the first gate line 1 or the second gate line 2, and no solder paste or conductive glue is required between the two. The conductive wire 5 is a soldering strip with a conductive coating on the surface. The base material of the soldering strip includes a copper strip, a copper wire, or a copper strip or copper wire with a coating or plating formed on the surface. The composition of the coating or plating includes one of tin-lead alloy, tin-lead-silver alloy, tin-lead-bismuth alloy, tin-silver-copper alloy and tin-silver alloy. The melting temperature of the conductive coating is not higher than 200°C, preferably below 150°C. The composition of the conductive coating includes a combination of one or more of tin, lead, indium, bismuth, silver, antimony, gallium, aluminum, zinc and copper. The conductive connection between the conductive wire 5 and the gate line is achieved by pressing at a certain temperature and pressure, the temperature is 120°C to 180°C, the pressure is between 0.01MPa and 0.1MPa, and the pressing time is 5 to 30 minutes. Low-temperature connection has little effect on thermal deformation of the battery cell, and the conductive wire 5 is not likely to deviate to the electrode grid line in the discontinuous area to cause a short circuit.

Claims

1. A back-contact solar cell comprising grid lines, wherein a plurality of grid lines extend along a first direction and have discontinuities along a second direction, and the discontinuities of two adjacent grid lines are staggered, characterized in that: A reinforcement portion with an increased size is provided on the gate line, and in the second direction, the reinforcement portion is at least partially collinear with the discontinuity region.

2. The back contact solar cell according to claim 1, characterized in that: The reinforcement portion is collinear with the discontinuity region.

3. The back contact solar cell according to claim 1, characterized in that: In the second direction, the distance between the reinforcement portion and the adjacent grid line is 0.2-5 mm.

4. The back contact solar cell according to claim 1 or 2, characterized in that: The thickness of the reinforcement portion is not less than the thickness of the gate line. The back-contact solar cell according to claim 1 , wherein the reinforcement portion is located in the middle and / or at the end of the grid line.

6. A battery assembly, characterized in that: The invention comprises the back-contact solar cell according to claim 1, and a conductive line (5), wherein the conductive line (5) passes through the discontinuity area and is conductively connected to the reinforcement part.

7. The battery assembly according to claim 6, characterized in that The conductive wire (5) is a strip-shaped conductive wire.

8. The battery assembly according to claim 6, wherein: The conductive wire (5) is a welding strip with a conductive coating.

9. The battery assembly according to claim 6, characterized in that The two ends of the conductive wire (5) are respectively connected to the reinforcement parts of the two battery slices, and the currents guided by the reinforcement parts at the two ends of the conductive wire (5) have opposite polarities.

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