CN217606833U

CN217606833U - Solar cell electrode grid line connection structure

Info

Publication number: CN217606833U
Application number: CN202220041446.9U
Authority: CN
Inventors: 周公庆
Original assignee: Tongwei Solar Meishan Co Ltd
Current assignee: Tongwei Solar Meishan Co Ltd
Priority date: 2022-01-07
Filing date: 2022-01-07
Publication date: 2022-10-18
Anticipated expiration: 2032-01-07

Abstract

The utility model discloses a solar cell electrode grid line connection structure belongs to solar cell technical field. The utility model discloses a solar cell electrode grid line connection structure, including the main grid and run through the vice bars of main grid, wherein the linkage segment that links to each other with the main grid overlap on the vice bars is fusiformis structure, and the inside of linkage segment is equipped with the trompil. The utility model discloses a connection structure to main bars and vice bars carries out optimal design to both can prevent main bars regional height fluctuation, can also effectively reduce the overlap area of the regional thick liquids of connection simultaneously, guarantee battery performance.

Description

Solar cell electrode grid line connection structure

Technical Field

The utility model belongs to the technical field of solar cell, more specifically relates to a solar cell electrode grid line connection structure.

Background

The electrode design in the silk-screen process has a great influence on the electrical performance of the battery and is also related to the process of the assembly. Particularly, in the existing TOPcon and HIT batteries, silver grid lines are printed on the front side and the back side of the battery at the same time, but the electrical property of the battery is seriously influenced by the appearance and the conductive condition of the grid lines, and the performance of the battery can be exerted only by reasonable grid line design. The printed patterns in the photovoltaic industry are developed from two main grids to 12 current main grids step by step, the width of grid lines is also from the initial 150-micron line width to 30 micron current, and even the recent meshless process can design the grid lines to 17-19 micron. The direction of grid line design is that the grid line design is thinner, and the grid line radical is denser. From the viewpoint of electrical design of the battery, the above designs are all designed to collect current more uniformly. On the one hand, the thinner grid lines can effectively reduce unit consumption and reduce the consumption of single silver, on the other hand, the shading area of the grid lines can be reduced, so that more incident light enters the front side of the battery, meanwhile, the size of the battery piece is larger and larger, the length of the thin grid lines on the battery is also longer and longer, and the influence of the transverse conductive resistance of the grid lines on the series resistance of the battery piece is larger and larger.

At present, the printing process of electrode flash in the industry is mainly divided into single printing and step printing methods. The proportion occupied by the step printing is higher, and the performances of the main grid paste and the fine grid paste can be respectively designed by the distributed printing. The main grid slurry mainly meets the aims of welding performance and current collection, the fine grid slurry needs to guarantee the extremely fine printing effect and guarantee the smoothness of printing, and on the other hand, the fine grid slurry needs to guarantee the PN junction surface layer below the fine grid slurry during sintering, so that the performances of the two kinds of slurry are completely different, and the fine grid slurry is difficult to give consideration to if one kind of slurry is used.

The current industry mainstream grid line pattern is shown in fig. 1 and fig. 2, which are a plurality of main grids 1, and a plurality of fine grids 2 (secondary grids) are vertically designed. One design scheme is that a thin grid is directly intersected with a main grid line, and the other scheme is that centipede legs are designed on the main grid, and contact ends designed on the thin grid line are overlapped with the centipede legs. At present, main grid line in the industry is thinner and thinner, main grid width is within 100 microns, thin grid line's width is also within 30 microns, and the superimposed height can reach more than 30 microns after two silver thick liquid grid lines that are so thin intersect, and present subassembly welding process all adopts mechanized welded equipment, so the roughness requirement to the grid line is higher, if main grid position height fluctuation is too big, it is too big to lead to welding area and main grid contact gap, the temperature is inhomogeneous, thereby bring partial rosin joint, the condition of partial overwelding. Meanwhile, if the scheme of the overlarge centipede legs is adopted, the printing area can be increased, the using amount of the slurry is increased, and meanwhile, the shading area of the slurry can also be increased, so that the electrical property is influenced. However, if the centipede legs are not connected at all, the overlapping area of the thin grid and the main grid paste is too small, so that the resistance is higher when the current in the thin grid is collected to the main grid, and the electrical performance is affected.

SUMMERY OF THE UTILITY MODEL

1. Problems to be solved

An object of the utility model is to solve the too big easy welding nature that influences of main bars position height fluctuation that current solar cell electrode major-minor bars connection structure exists, perhaps the great easy problem that influences the electric property of main-minor bars connection area thick liquids printing area, and provide a solar cell electrode grid line connection structure. The utility model discloses a connection structure to main bars and vice bars carries out optimal design to both can prevent main bars regional height fluctuation, can also effectively reduce the overlap area of the regional thick liquids of connection simultaneously, guarantee battery performance.

2. Technical scheme

In order to solve the above problem, the utility model discloses the technical scheme who adopts as follows:

the utility model discloses a solar cell electrode grid line connection structure, including the main grid and run through the vice bars of main grid, wherein the linkage segment that links to each other with the main grid overlap on the vice bars is fusiformis structure, and the inside of linkage segment is equipped with the trompil.

Furthermore, the width of the connecting section is gradually reduced from the center of the main grid to the two ends.

Further, the length of the connecting section is 0.8-3mm, the maximum width is 50-80 microns, and the minimum width is 15-40 microns.

Furthermore, the opening is positioned in the center of the connecting section, and the maximum dimension of the opening along the width direction of the secondary grid is 20-50 microns.

Further, the openings are circular and have a diameter of 20 to 50 microns.

Further, the number of the openings is multiple.

Furthermore, the open pore is a square pore, and the side length of the square pore is 20-50 microns.

Furthermore, the open holes are long holes extending along the length direction of the secondary grid.

Furthermore, the width of the main gate is 50-100 microns, and the width of the auxiliary gate is 17-30 microns.

3. Advantageous effects

Compared with the prior art, the beneficial effects of the utility model are that:

(1) The utility model discloses a solar cell electrode grid line connection structure is spindle-shaped structure through the linkage segment design that links to each other with the main grid overlap on with the vice bars to both can effectively prevent the phenomenon of main grid connection region height fluctuation, vice bars width increase area is minimum simultaneously, compares conventional centipede leg overlap mode, can obviously reduce the shading area, effectively improves the electric current of battery piece, thereby improves the electrical property.

(2) The utility model discloses a solar cell electrode grid line connection structure, its vice bars run through the main bars, and set up the trompil inside the linkage segment to can reduce the consumption of the height of main and vice bars overlap area and silver thick liquid, guarantee the smoothness nature of printing, also can guarantee simultaneously that vice bars and main bars overlap position highly can not influence the welding, make shading area and thin bars and main bars handing-over area can reach the best balance.

(3) The utility model discloses a solar cell electrode grid line connection structure, this connection structure not only are applicable to P type battery positive grid line pattern, and to P type back aluminium grid pattern, N type battery and positive back all need print silver grid line equally be suitable for.

Drawings

FIG. 1 is a schematic diagram of a conventional primary and secondary grid connection method (I) for electrodes;

FIG. 2 is a schematic diagram of a conventional electrode primary and secondary grid connection method (II);

fig. 3 is a schematic structural view of a main-auxiliary gate connection structure of embodiment 1;

FIG. 4 is a schematic diagram of a main gate structure of embodiment 4;

FIG. 5 is a schematic view of the main gate structure of embodiment 3;

FIG. 6 is a schematic diagram of the structure of a main grid with delay openings in example 2;

fig. 7 is a schematic structural diagram of a main gate with multiple openings in embodiment 2.

In the figure: 1. a main grid; 2. a secondary gate; 3. a connecting section; 4. and (5) opening holes.

Detailed Description

At present, the existing solar cell generally adopts a step-by-step printing process, namely, a main grid slurry is printed on a silicon wafer substrate by using a screen printing plate, then the silicon wafer substrate is dried, then an auxiliary grid slurry is printed for sintering, and finally an integral printing pattern is formed on the surface of a cell. However, an overlapping area is formed between the main grid and the auxiliary grid, and the thickness of the overlapping area is basically equal to the superposition of the printing heights of two times, so that the fluctuation is formed near the main grid area, automatic welding displacement is easily caused, meanwhile, organic matters in the slurry at the bottom are not sufficiently volatilized in the sintering process, or the temperature and the components are different from those of the surrounding normal area, and the abnormity on welding or electrical property is easily caused.

Based on the circumstances, this application carries out optimal design through the connection structure to vice bars and main bars to both can effectively prevent the phenomenon of main bars connection area height fluctuation, vice bars width increase area is minimum simultaneously, compares conventional centipede leg overlap mode, can obviously reduce the shading area, effectively improves the electric current of battery piece, thereby improves the electrical property.

The present invention will be further described with reference to the following specific embodiments.

Example 1

As shown in fig. 3, the solar cell electrode grid line connection structure of the present embodiment includes a main grid 1 and a secondary grid 2 penetrating through the main grid 1, wherein the secondary grid 2 is overlapped and connected with the main grid 1 through a connection section 3, the connection section 3 is a spindle-shaped structure, a width of the connection section is gradually reduced from a center of the main grid 1 to two ends, a length of the connection section 3 in the present embodiment is 2mm, a maximum width is 80 micrometers, and a minimum width is 40 micrometers. In the embodiment, the connecting section 3 is designed into a spindle-shaped structure, and the structural size of the connecting section is optimized, and the area of the width increase of the auxiliary grid is extremely small, so that compared with the conventional centipede leg overlapping mode, the shading area can be obviously reduced, the current of the battery piece can be effectively improved, and the electrical property is improved; meanwhile, the increased silver paste usage amount is small, so that compared with a conventional connection scheme, the method can save the paste, and is favorable for reducing the cost.

Further optimize, the inside center of linkage segment 3 is equipped with trompil 4 in this embodiment, and its maximum dimension along 2 width direction of auxiliary grid is 50 microns, can effectively reduce the height of overlap region through the setting of trompil 4, reduces the consumption of silver thick liquid to can guarantee the smoothness nature of printing, also can guarantee simultaneously that the height of main and auxiliary grid overlap position can not influence the welding, shading area and main and auxiliary grid handing-over area can reach the best balance.

The specific process route of the production process of the solar cell in the embodiment is as follows:

1. texturing: and performing alkaline texturing on two sides of the single crystal P-type silicon wafer to form a pyramid textured structure.

2. Diffusion: the silicon wafer after the texturing reacts with phosphorus oxychloride at high temperature and under the condition of oxygen introduction, phosphorus doping is carried out, an N-type emitter is obtained to form a core PN junction of the solar cell, and the sheet resistance after diffusion is 200 omega/sq.

3. Laser SE: and performing laser doping on the front grid line metalized area by using the surplus phosphorosilicate glass generated in the diffusion process as a phosphorus source to form a re-diffusion area, wherein the sheet resistance is 95 omega/sq.

4. Pre-oxidation: and carrying out oxidation protection on the front side of the cell after the laser SE.

5. Removing PSG: and under the action of HF, removing the phosphorosilicate glass layer on the back and the edge.

6. Alkali polishing: back side polishing and front side PSG removal.

7. Annealing: an oxide layer is formed on the back surface at high temperature to prepare for back passivation.

8. Back film: and plating a passivation film with an aluminum oxide and a multi-layer silicon nitride structure on the back of the silicon wafer through PECVD.

9. Film preparation: plating an antireflection film on the front surface of the silicon chip.

10. Back laser: and (5) perforating the back passivation film by using laser.

11. Back electrode printing: and screen printing a back electrode and an aluminum grid line.

12. Printing a front electrode and a grid line: adopting an SE laser graph corresponding to the design of the auxiliary grid to carry out SE laser propulsion in the area of the auxiliary grid; and preparing a main grid and an auxiliary grid at corresponding positions on the front surface of the silicon wafer by adopting a screen printing mode, wherein a high-precision camera is used for capturing a laser MARK point mode for alignment, so that the precision is ensured, and the specification of the screen plate adopts a screen plate with low sand thickness and low film thickness.

13. And (3) sintering: and performing hydrogen passivation and electrode silicon chip co-sintering at high temperature.

14. Electric injection: and performing electro-injection treatment on the sintered battery piece.

15. And (3) finished product: and testing, sorting, packaging and warehousing the product battery piece.

Example 2

The solar cell electrode grid line connection structure of this embodiment, including main grid 1 and the vice grid 2 that runs through main grid 1, wherein vice grid 2 passes through linkage segment 3 and links to each other with main grid 1 overlap, and this linkage segment 3 is fusiform structure, and its width reduces to both ends by main grid 1 center gradually, and the length of linkage segment 3 is 3mm in this embodiment, and maximum width is 60 microns, and minimum width is 27 microns. As shown in fig. 6, the inner center of the connecting section 3 in this embodiment is provided with an opening 4, the opening 4 is circular and has a diameter of 20 μm, and as shown in fig. 7, the number of the openings may be plural.

The production process of the solar cell of the embodiment comprises the following specific process routes:

2. Diffusion: the textured silicon wafer reacts with phosphorus oxychloride at high temperature and under the condition of oxygen introduction to perform phosphorus doping to obtain an N-type emitter to form a core PN junction of the solar cell, and the sheet square resistance after diffusion is 150 omega/sq.

3. Laser SE: and performing laser doping on the front grid line metalized area by using the surplus phosphorosilicate glass generated in the diffusion process as a phosphorus source to form a re-diffusion area, wherein the sheet resistance is 80 omega/sq.

6. Alkali polishing: back side polishing and front side PSG removal.

10. Back laser: and (5) perforating the back passivation film by using laser.

13. And (3) sintering: and carrying out hydrogen passivation and electrode silicon wafer co-sintering at high temperature.

14. Electric injection: and carrying out electro-injection treatment on the sintered cell.

15. And (3) finished product: and testing, sorting, packaging and warehousing the product battery pieces.

Example 3

The structure of the solar cell electrode grid line connection structure of this embodiment is basically the same as that of embodiment 1, and the difference is that: as shown in fig. 5, in this embodiment, the length of the connecting section 3 is 1mm, the maximum width is 50 micrometers, the minimum width is 15 micrometers, the inner center of the connecting section 3 is provided with an opening 4, the opening 4 is a square hole, and the side length of the square hole is 25 micrometers.

Example 4

The structure of the solar cell electrode grid line connection structure of this embodiment is basically the same as that of embodiment 1, and the difference is that: as shown in fig. 4, the opening 4 in this embodiment is a long hole extending along the length direction of the sub-grid.

Claims

1. The utility model provides a solar cell electrode grid line connection structure which characterized in that: the combined type grid structure comprises a main grid (1) and an auxiliary grid (2) penetrating through the main grid (1), wherein a connecting section (3) which is overlapped and connected with the main grid (1) on the auxiliary grid (2) is of a spindle-shaped structure, and an opening (4) is formed in the connecting section (3).

2. The solar cell electrode grid line connection structure of claim 1, wherein: the width of the connecting section (3) is gradually reduced from the center of the main grid (1) to two ends.

3. The solar cell electrode grid line connection structure of claim 2, wherein: the length of the connecting section (3) is 0.8-3mm, the maximum width is 50-80 microns, and the minimum width is 15-40 microns.

4. The solar cell electrode grid line connection structure as claimed in any one of claims 1 to 3, wherein: the opening (4) is positioned in the center of the connecting section (3), and the maximum dimension of the opening along the width direction of the auxiliary grid (2) is 20-50 microns.

5. The solar cell electrode grid line connection structure of claim 4, wherein: the opening (4) is circular and has a diameter of 20-50 microns.

6. The solar cell electrode grid line connection structure of claim 5, wherein: the number of the openings is multiple.

7. The electrode grid line connection structure of claim 4, wherein: the opening (4) is a square hole, and the side length of the square hole is 20-50 micrometers.

8. The electrode grid line connection structure of claim 4, wherein: the open pore (4) is a long hole extending along the length direction of the auxiliary grid.

9. The electrode grid line connection structure of any one of claims 1 to 3, wherein: the width of the main gate (1) is 50-100 microns, and the width of the auxiliary gate (2) is 17-30 microns.