Back electrode pattern structure of crystalline silicon solar cell

Abstract

The present invention belongs to the field of photovoltaic power generation technology, and in particular relates to a back electrode pattern structure for a crystalline silicon solar cell, comprising an electrode pattern located on the back of the cell, wherein the electrode pattern comprises a main grid, a secondary grid, and a pad point, wherein the main grid and the pad point are layers of silver paste, and the secondary grid is a layer of aluminum paste. The back electrode pattern structure for a crystalline silicon solar cell provided by the present invention replaces aluminum paste with silver paste in the material of the main grid, increases the number of pad points, designs a secondary grid bus bar, strengthens the current conduction capacity of the main grid, is conducive to increasing short-circuit current, and reduces series resistance, thereby increasing component power and reducing internal electrical losses. At the same time, in order to reduce process precision requirements, a secondary grid gradient thickening structure is designed to ensure good contact between the secondary grid substrate and the pad point.

Description

Technical Field

[0001] The invention belongs to the technical field of photovoltaic power generation and relates to a back electrode graphic structure of a crystalline silicon solar cell. Background Art

[0002] In recent years, continuous advancements in solar technology, resulting in declining production costs and increasing conversion efficiency, have led to the increasing popularity and rapid development of photovoltaic power generation. As the path to grid parity for photovoltaic power generation accelerates, the market has shifted from prioritizing high power to a comprehensive focus on high power, stable power generation over time under all installation conditions, low attenuation, and low cost, ultimately reducing the cost of electricity (Cost of Electricity) at the user end. Therefore, effectively reducing the cost of electricity (Cost of Electricity) has become a widespread concern in the industry, with photovoltaic modules, the core components of photovoltaic systems, being a top priority. High module power is a necessary technological step towards achieving grid parity, and increasing module luminous flux and reducing internal electrical losses are currently the primary pathways for increasing module power. The core component that further determines the specific energy output of a photovoltaic module is the solar cell. The metal electrode fabrication, the final step in the production of crystalline silicon solar cells, is also crucial for determining the internal resistance losses and the ability to successfully extract the photogenerated current, depending on the welding method used to connect the modules in series or parallel. In this process, consumables such as precious metal slurries and precision screens have long accounted for the vast majority of non-silicon costs in battery preparation materials. Therefore, the design and manufacture of the front and back metal electrodes of crystalline silicon solar cells, especially the front Ag metal electrodes, are closely related to their mass production costs.

[0003] To reduce silver paste consumption, crystalline silicon solar cells currently use aluminum paste for the back electrodes and secondary grids, while silver paste is used for the pads. This design reduces production costs, but aluminum's weaker conductivity compared to silver makes it difficult to increase the power of the cell module, resulting in higher internal electrical losses. Summary of the Invention

[0004] The object of the present invention is to provide a back electrode pattern structure for a crystalline silicon solar cell in order to solve the above problems.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A back electrode pattern structure of a crystalline silicon solar cell includes an electrode pattern located on the back of the cell, wherein the electrode pattern includes a main grid, a secondary grid and a pad point, wherein the main grid and the pad point are silver paste layers, and the secondary grid is an aluminum paste layer.

[0007] Furthermore, the auxiliary grid includes several auxiliary grid bases and auxiliary grid bus bars, the auxiliary grid bases are connected to the auxiliary grid bus bars, each auxiliary grid bus bar is divided into several sections of auxiliary grid bus bars arranged in a straight line, a pad point is provided between each two adjacent sections of auxiliary grid bus bars, and the ends of the auxiliary grid bus bars are connected to the pad point.

[0008] Furthermore, several sub-grid substrates are connected to the pad points, or directly connected to the sub-grid busbars.

[0009] Furthermore, when the auxiliary grid base is connected to the pad point, the end where the auxiliary grid base is connected to the pad point is provided with an auxiliary grid gradient thickening structure, the width of the auxiliary grid gradient thickening structure gradually increases from the edge of the pad point to the center, and the auxiliary grid gradient thickening structure is fixedly connected to the pad point.

[0010] Furthermore, the secondary grid gradually thickened structure is in the shape of a teardrop, and the width at the widest point is 0.3 mm.

[0011] Furthermore, the main grid includes a plurality of main grid lines, the main grid lines are perpendicular to the auxiliary grid base, the auxiliary grid busbars are parallel to the main grid lines, and an auxiliary grid busbar is provided on both sides of each main grid line.

[0012] Furthermore, the pad point (3) includes a large pad point and a small pad point, wherein the large pad point is arranged at the head and / or tail of each main grid line (11) of each half-cell, and a plurality of small pad points are distributed at equal intervals along the length direction of each main grid line (11).

[0013] Furthermore, the length of the large pad point is 2.6mm and the width is 1.6mm, the length of the small pad point is 1.6mm and the width is 1mm, the width of the main grid line is 0.15mm, the width of the auxiliary grid bus bar is 0.12mm, and the width of the auxiliary grid base is 0.12mm.

[0014] Furthermore, one side of each large pad point is connected to three sub-gate substrates, and one side of each small pad point is connected to one sub-gate substrate.

[0015] Furthermore, the end of each segment of the auxiliary grid bus bar is connected to the end of the auxiliary grid gradually thickened structure away from the pad point through an arc structure.

[0016] Compared with the existing technology, the advantages of the present invention are:

[0017] The back electrode pattern structure of the crystalline silicon solar cell provided by this invention replaces aluminum paste with silver paste for the main grid, increases the number of pads, and incorporates a secondary grid busbar to enhance the main grid's current conduction capacity, thereby increasing short-circuit current and reducing series resistance, thereby increasing module power and reducing internal electrical losses. Furthermore, to reduce process precision requirements, a gradual thickening of the secondary grid ensures good contact between the secondary grid substrate and the pads.

[0018] Other advantages, objectives and features of the present invention will be reflected in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural diagram of the prior art.

[0020] Figure 2 Schematic diagram of the main grid and pad points of the present invention.

[0021] Figure 3 Schematic diagram of the auxiliary grid of the present invention.

[0022] Figure 4 It is a structural schematic diagram of the present invention.

[0023] Figure 5 yes Figure 4 A in the enlarged view.

[0024] In the figure: main grid 1, main grid line 11, auxiliary grid 2, auxiliary grid base 21, auxiliary grid gradually thickened structure 22, auxiliary grid bus bar 23, arc structure 24, pad point 3, half-cell battery cell 100. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0026] like Figure 1 To reduce silver paste consumption, aluminum paste is currently used for the back electrodes and secondary grids of crystalline silicon solar cells, while silver paste is used for the pads. This design reduces production costs, but aluminum's weaker conductivity compared to silver makes it difficult to increase the power of the solar cell module, resulting in higher internal electrical losses.

[0027] The present invention provides a back electrode pattern structure of a crystalline silicon solar cell, such as Figure 4As shown, the electrode pattern on the back of the cell includes a main grid 1, a secondary grid 2, and pads 3. The main grid 1 and pads 3 are made of silver paste, while the secondary grid 2 is made of aluminum paste. Compared to existing cell designs, replacing the aluminum paste with silver paste enhances current transmission capacity, reduces the series resistance of the photovoltaic module, and increases the short-circuit current of the photovoltaic module.

[0028] Switching the main grid from aluminum paste to silver paste changes the pad shape and size. This design enhances conductivity, improves component performance, and reduces losses. However, due to machine precision limitations, contact between the aluminum-paste secondary grid and the silver-paste main grid cannot be guaranteed. Therefore, the present invention provides a secondary grid 2 to ensure contact between the aluminum-paste secondary grid and the silver-paste main grid.

[0029] Specifically, if Figure 3 As shown, the auxiliary grid 2 includes several auxiliary grid bases 21 and auxiliary grid bus bars 23. The auxiliary grid bases 21 are connected to the auxiliary grid bus bars 23. Each auxiliary grid bus bar 23 is divided into several segments of auxiliary grid bus bars 23 arranged in a straight line. A pad point 3 is provided between each two adjacent segments of auxiliary grid bus bars 23, and the ends of the auxiliary grid bus bars 23 are connected to the pad point 3.

[0030] The end of each auxiliary grid busbar 23 is connected to the end of the auxiliary grid gradually thickened structure 22 away from the pad point 3 through an arc structure 24. The main function of the auxiliary grid busbar 23 is to enhance current conduction, which helps reduce internal electrical losses, increase short-circuit current, lower series resistance, and thus improve module power. The shape of the end of the auxiliary grid busbar 23 can change with the shape of the pad point and is not limited to a circular arc.

[0031] Several sub-grid substrates 21 are connected to the pad points 3 or directly connected to the sub-grid busbars 23 .

[0032] When the auxiliary grid base 21 is connected to the pad point 3, the end of the auxiliary grid base 21 connected to the pad point 3 is provided with an auxiliary grid gradually thickening structure 22. The width of the auxiliary grid gradually thickening structure 22 gradually increases from the edge to the center of the pad point 3. The auxiliary grid gradually thickening structure 22 is fixedly connected to the pad point 3. The design of the auxiliary grid gradually thickening structure 22 strengthens the connection between the auxiliary grid base 21 and the pad point 3, reduces the process precision requirements, and ensures a good connection between the auxiliary grid base and the pad point.

[0033] The secondary grid gradually thickened structure 22 can be in various shapes with gradually increasing width. In this embodiment, the secondary grid gradually thickened structure 22 is in the shape of a water drop, and the width at the widest point is 0.3 mm.

[0034] The main grid 1 includes a plurality of main grid lines 11 . The main grid lines 11 are perpendicular to the auxiliary grid base 21 . The auxiliary grid bus bars 23 are parallel to the main grid lines 11 . A auxiliary grid bus bar 23 is provided on both sides of each main grid line 11 .

[0035] The pad point 3 includes a large pad point and a small pad point. The large pad point has a length of 2.6 mm and a width of 1.6 mm, and the small pad point has a length of 1.6 mm and a width of 1 mm. Figure 2 As shown, two large pads and six small pads are provided on each busbar 11 of each half-cell 100. The two large pads are located at the beginning and end of the busbar 11, and the six small pads are located between the two large pads, and are evenly spaced along the length of the busbar 11. Compared with existing cell designs, this increases the number of pads, reduces the pad area, reduces silver paste consumption, and enhances current transmission.

[0036] The width of the main grid line 11 is 0.15 mm, the width of the auxiliary grid bus bar 23 is 0.12 mm, and the width of the auxiliary grid base 21 is 0.12 mm.

[0037] like Figure 5 As shown, one side of each large pad is connected to three auxiliary grid bases 21, and one side of each small pad is connected to one auxiliary grid base 21. The arc structure 24 is connected to the closest auxiliary grid base 21, thereby interconnecting the auxiliary grid base 21, the auxiliary grid bus bar 23 and the pad 3.

[0038] The electrode pattern structure of the present invention is compatible with various sizes, including 158, 166, 180, and 210. The back electrode pattern structure of the crystalline silicon solar cell provided by the present invention replaces aluminum paste with silver paste in the main grid material, increases the number of pads, and incorporates a secondary grid busbar, enhancing the main grid's current conduction capacity. This helps increase short-circuit current and reduce series resistance, thereby increasing module power and reducing internal electrical losses. Furthermore, to reduce process precision requirements, a gradual thickening of the secondary grid structure is designed to ensure good contact between the secondary grid substrate and the pads.

[0039] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described, or replace them with similar methods without departing from the spirit of the present invention.

Claims

1. A back electrode pattern structure of a crystalline silicon solar cell, comprising an electrode pattern located on the back side of the cell, characterized in that: The electrode pattern includes a main grid (1), a secondary grid (2) and a pad point (3), wherein the main grid (1) and the pad point (3) are silver paste layers, and the secondary grid (2) is an aluminum paste layer; the secondary grid (2) includes a plurality of secondary grid substrates (21) and secondary grid bus bars (23), wherein the secondary grid substrates (21) are connected to the secondary grid bus bars (23), and each secondary grid bus bar (23) is divided into a plurality of segments of secondary grid bus bars (23) arranged in a straight line, wherein a pad point (3) is provided between each two adjacent segments of the secondary grid bus bars (23), and the end of the secondary grid bus bar (23) is connected to the pad point (3); a plurality of secondary grid substrates (21) are connected to the pad point (3), or to the secondary grid bus bars. (23) is directly connected; when the auxiliary grid substrate (21) is connected to the pad point (3), the end portion where the auxiliary grid substrate (21) is connected to the pad point (3) is provided with an auxiliary grid gradient thickening structure (22), and the auxiliary grid gradient thickening structure (22) is fixedly connected to the pad point (3); the pad point (3) includes a large pad point and a small pad point, wherein the large pad point is arranged at the head and / or tail of each main grid line (11) of each half-cell battery sheet, and a plurality of small pad points are distributed at equal intervals along the length direction of each main grid line (11), one side of each large pad point is connected to three auxiliary grid substrates (21), and one side of each small pad point is connected to one auxiliary grid substrate (21).

2. The back electrode pattern structure of a crystalline silicon solar cell according to claim 1, characterized in that: The width of the secondary grid gradually thickened structure (22) increases gradually from the edge of the pad point (3) toward the center.

3. The back electrode pattern structure of a crystalline silicon solar cell according to claim 2, characterized in that: The secondary grid gradually thickened structure (22) is in the shape of a water drop, and the width at the widest point is 0.3 mm.

4. The back electrode pattern structure of a crystalline silicon solar cell according to claim 1, characterized in that: The main grid (1) comprises a plurality of main grid lines (11), wherein the main grid lines (11) are perpendicular to the auxiliary grid base (21), the auxiliary grid bus bars (23) are parallel to the main grid lines (11), and an auxiliary grid bus bar (23) is provided on both sides of each main grid line (11).

5. The back electrode pattern structure of a crystalline silicon solar cell according to claim 1, characterized in that: The large pad point has a length of 2.6 mm and a width of 1.6 mm, the small pad point has a length of 1.6 mm and a width of 1 mm, the main grid line (11) has a width of 0.15 mm, the auxiliary grid busbar (23) has a width of 0.12 mm, and the auxiliary grid base (21) has a width of 0.12 mm.

6. The back electrode pattern structure of a crystalline silicon solar cell according to claim 2, characterized in that: The end of each section of the auxiliary grid busbar (23) is connected to an end of the auxiliary grid gradually thickened structure (22) away from the pad point (3) through an arc structure (24).

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