CN216120314U

CN216120314U - High-efficiency laminated solar cell and front electrode thereof

Info

Publication number: CN216120314U
Application number: CN202121578210.0U
Authority: CN
Inventors: 黄智�; 周公庆; 肖俊峰; 刘宗刚; 马列; 张家峰; 郭兴刚; 姚骞; 尹丙伟; 李岩; 蒋卫鹏; 萧圣义
Original assignee: Tongwei Solar Meishan Co Ltd
Current assignee: Tongwei Solar Meishan Co Ltd
Priority date: 2021-07-12
Filing date: 2021-07-12
Publication date: 2022-03-22
Anticipated expiration: 2031-07-12

Abstract

The utility model discloses a high-efficiency laminated solar cell and a front electrode thereof, belonging to the technical field of solar cells. The front side electrode of the high-efficiency shingled solar cell comprises a front side main grid and a plurality of front side auxiliary grids which are vertically connected with the front side main grid and are distributed at intervals, wherein the front side main grid consists of a plurality of welding points which are distributed at intervals and thin main grids connected between adjacent welding points, and the distribution positions of the welding points respectively correspond to each front side auxiliary grid. According to the utility model, the front electrode pattern is optimally designed, so that the collection efficiency of front current can be effectively improved, the production cost is reduced, and the technical limitation of high resistance of a laminated walking dense grid is broken.

Description

High-efficiency laminated solar cell and front electrode thereof

Technical Field

The utility model belongs to the technical field of solar cells, and particularly relates to a high-efficiency laminated solar cell and a front electrode thereof.

Background

The laminated assembly is formed by redesigning the grid line of a complete battery piece into a pattern which can be reasonably cut into small pieces, then cutting the battery piece into a plurality of small battery pieces with complete current loops, and bonding the positive and negative electrodes of each small piece in a staggered manner through conductive adhesive. The shingled assembly abandons the welding strip tandem battery structure of the traditional assembly, so that the gap in the assembly can be fully utilized, the light receiving area is increased, meanwhile, the non-welding strip design is adopted, the line loss of the assembly is reduced, and the output power of the assembly can be greatly improved.

At present, the main grid of the laminated cell generally adopts a hollowed-out full main grid (such as chinese patent CN 109888045A) or a PAD point design (such as CN 211182221U) for reference of the MBB main grid to balance the mutually-restricted condition factors of reliability of laminated connection, module power, silver paste consumption cost and the like. The laminated tile is generally arranged at the positions of the positive and negative main grids, and the direction of the laminated tile is parallel to the direction of the positive and negative main grids. The design causes that the positive and negative main grid slurry is too high and cannot compete with MBB in cost; meanwhile, the hollow full-main-grid design is adopted, and the effective welding area is also influenced.

The design of the secondary grid is mostly in a traditional H-shaped design, the secondary grid is distributed in parallel and at equal intervals and is perpendicular to the welding direction of the main grid and the laminated tile slice, so that the current collected from the front side is directly transmitted to the main grid through the secondary grid and is directly led out through the whole main grid, or is transversely transmitted to a PAD point on the main grid and then is led out, for example, in the modes disclosed in Chinese patents CN110444625A and CN 211182221U. At this time, the length of the sub-gate is much longer than the designed length of the MBB cell, and taking the current comparison between the laminated tile 6 slice and 12BB as an example, the length of the sub-gate is about 33mm, the length of the sub-gate is about 8-9mm, and the difference between the lengths is about 4 times, so that the FF loss caused by the sub-gate resistance affects the conversion efficiency of the cell by more than 0.2%, and the main limitation condition of adopting the dense-gate high-impedance improvement effect is also met. Meanwhile, in the production process, EL grid breakage and the like can seriously affect the whole production, and are not beneficial to continuous production and further cost control.

Chinese patent CN 213242563U provides a design mode of a laminated tile secondary grid on the structure of a conventional MBB battery grid line, the application designs the secondary grid (thin grid) to be parallel to the welding direction of a laminated tile slice, 10-12 PAD points are arranged at the overlapped welding position of the laminated tile as welding points of positive and negative main grids, each PAD point is provided with a secondary main grid perpendicular to the secondary grid, the current collected on the front side of the design is directly transmitted to the secondary main grid through the secondary grid and then is transmitted to the PAD point through the secondary main grid and then is led out, thereby the length of the secondary grid can be obviously reduced and reaches the level of the MBB secondary grid. But at this time, the length of the auxiliary main grid is the width of the shingled slice, which makes the auxiliary main grid become a main bottleneck limiting the whole current transmission; and the secondary grid adopts the design parallel to the welding direction of the laminated tile slices, and is not the optimal design for the whole current collection stroke. Meanwhile, if the welding strip welding mode is adopted on the auxiliary main grid to assist current transmission on the auxiliary main grid, the problem of efficiency reduction caused by the distance of the auxiliary main grid can be solved, additional manufacturing processes and procedures are needed for welding the newly added welding points, the cost is increased due to the influence of yield and fragment rate caused by the procedure increase, equipment investment and the like, and meanwhile, the compatibility of welding strip welding and the welding of the laminated tile assembly also brings challenges.

In addition, as MBB cells and modules are developed, the power gain of the module due to the packaging density advantage of the tiled module is continuously shrinking; the design of the main grid of the laminated assembly is in a disadvantage in silver paste unit consumption, and further improvement and optimization are needed; due to the limitation of damage and capacity brought by slicing, the slicing is generally 5-7 slicing at present, and the corresponding grid line design is equivalent to the grid line design of a 5-7 main grid of a conventional battery piece, so that the future dense grid high-lift efficiency is not facilitated. Therefore, how to further improve the efficiency and reduce the cost is a problem to be solved urgently by the technology of the laminated assembly.

SUMMERY OF THE UTILITY MODEL

1. Problems to be solved

The utility model aims to overcome the defect that the realization of dense grid high-lift efficiency of a laminated solar cell is limited due to the influence of electrode pattern design, and provides a high-efficiency laminated solar cell and a front electrode thereof. According to the utility model, the front electrode pattern is optimally designed, so that the collection efficiency of front current can be effectively improved, the production cost is reduced, and the technical limitation of high resistance of a laminated walking dense grid is broken.

2. Technical scheme

In order to solve the problems, the technical scheme adopted by the utility model is as follows:

the front side electrode of the high-efficiency shingled solar cell comprises a front side main grid and a plurality of front side auxiliary grids which are vertically connected with the front side main grid and are distributed at intervals, wherein the front side main grid consists of a plurality of welding points which are distributed at intervals and thin main grids connected between adjacent welding points, and the distribution positions of the welding points respectively correspond to each front side auxiliary grid.

Furthermore, the welding spots are composed of front large welding spots and front small welding spots with different sizes.

Furthermore, the number of the large welding points on the front surface of each front surface main grid is 8-20.

Furthermore, the shape of the welding spot is a polygon.

Furthermore, the shape of the welding spots is trapezoid, wherein the pattern length of the small welding spots on the front surface of the trapezoid is 0.2-1.0mm, the width of the short side is 0.05-1.0mm, and the width of the long side is 0.2-1.5 mm; the pattern length of the big welding points on the front surface of the trapezoid is 0.4-1.5mm, the width of the short side is 0.2-1.5mm, and the width of the long side is 0.3-2.0 mm.

Furthermore, the front side auxiliary grid consists of a first auxiliary grid and a second auxiliary grid, wherein the first auxiliary grid corresponds to the small welding point on the front side, the second auxiliary grid corresponds to the large welding point on the front side, and the width of the second auxiliary grid is 1.5-10 times that of the first auxiliary grid.

Furthermore, two continuous anti-breaking grid lines perpendicular to the front side auxiliary grids are arranged between the front side auxiliary grids.

Furthermore, the width of the breakage-proof grid line is 1.2-2 times of the width of the front side auxiliary grid line.

Further, the thin main grid is composed of a rectangle or an S-curve.

Furthermore, the thin main grid is composed of rectangles, and the width of the thin main grid is 0.01-0.2 mm.

Furthermore, the front side auxiliary grids adopt a gradual change design with 2-10 sections, and the distance between the adjacent front side auxiliary grids is 1.00-1.32 mm.

Furthermore, the front side auxiliary grid adopts a four-section bamboo joint gradual change design, the width difference of each section of grid line is 2-10 mu m, and the length of each section is increased along with the reduction of the width of the line width.

The utility model relates to a high-efficiency laminated solar cell which is formed by sequentially welding a plurality of laminated cell sheets in a superposition mode, wherein the front surface of each laminated cell sheet is provided with a front surface electrode.

Furthermore, the back surface of each laminated cell is provided with a back electrode, the front electrode and the back electrode are respectively positioned at two opposite sides of the front surface and the back surface of each laminated cell, and the adjacent laminated cells are connected with each other through the front electrode and the back electrode in a stitch welding manner.

Furthermore, the back electrode is composed of a silver main grid electrode and an aluminum electrode, the aluminum electrode is electrically connected with the silver main grid electrode, the silver main grid electrode is composed of a plurality of welding points which are distributed at intervals and a silver fine main grid which is connected between the adjacent welding points, and the welding points are composed of back small welding points and back large welding points which respectively correspond to the number and the positions of the welding points on the front main grid.

Furthermore, the pattern of the small welding spot on the back surface is square, and the side length of the pattern is 0.4-1.2 mm; the pattern of the large welding spot on the back is rectangular, the length of the pattern is 1.2-2.5mm, and the width of the pattern is 0.5-2.2 mm.

Furthermore, the silver fine main grid is rectangular, and the width of the silver fine main grid is 0.05-0.5 mm.

Furthermore, the silver main grid electrode is connected with the aluminum electrode through a large back welding spot.

Furthermore, the aluminum electrode is composed of an aluminum main grid and an aluminum auxiliary grid, the aluminum auxiliary grid is distributed on one side of the aluminum main grid at intervals and is vertically connected with the aluminum main grid, and the other side of the aluminum main grid is connected with the back large welding point.

3. Advantageous effects

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

(1) according to the front electrode of the efficient laminated solar cell, the pattern of the front electrode is optimally designed, the structural form of the welding spots and the thin main grids is adopted, the size of the welding spots can be adjusted according to needs, so that the consumption of the main grid slurry corresponding to the front and back surfaces can be reduced on the premise of ensuring the effective welding area of the assembly, and the manufacturing cost is greatly reduced; simultaneously for current stack tile battery positive electrode structure, can also effectively reduce contact resistance on the basis that does not change silver thick liquid consumption, and then be favorable to improving current collection efficiency.

(2) According to the front electrode of the high-efficiency laminated solar cell, the welding spots on the front main grid are composed of the front large welding spots and the front small welding spots which are different in size, so that the contact resistance can be reduced as much as possible on the basis of ensuring the effective welding area of the assembly, and meanwhile, the width of the auxiliary grid connected with the front large welding spots is increased through the arrangement of the front large welding spots, and the current collection efficiency is further improved.

(3) According to the front electrode of the efficient laminated solar cell, two anti-breaking grid lines which are continuous in pulling and are perpendicular to the front auxiliary grids are arranged between the front auxiliary grids, so that on one hand, the phenomenon of grid breaking can be prevented from affecting the normal work of the cell, and on the other hand, part of current collected by the front auxiliary grids is directly transmitted to welding points of the main grids to be led out; one part of the grid lines are transmitted to the auxiliary grid connected with the large welding spot on the front surface through the anti-breaking grid lines and then transmitted to the large welding spot for leading out, so that the collection efficiency of the front current can be effectively improved, and the technical limitation of high resistance of a laminated dense grid is broken.

(4) According to the efficient laminated solar cell, the structure of the front electrode is optimized, particularly, the combination mode of the main grid welding spot and the thin main grid is adopted, and the breakage-proof grid line is matched, so that the collection efficiency of front current can be effectively improved, the production cost is reduced, and the development of a laminated dense grid in a high resistance direction is facilitated.

(5) According to the efficient laminated solar cell, 100% of effective welding contact of the front main grid is ensured through back electrode pattern design, and the consumption of the front main grid can be reduced to the maximum extent on the premise that the consumption of the back electrode is increased properly. Due to the price difference of the front and back main grid silver paste, the comprehensive cost is greatly reduced.

(6) According to the efficient laminated solar cell, the photoelectric conversion efficiency of the laminated PERC cell can be improved by over 0.1%, the consumption of front silver is reduced by 20mg, and the consumption of back silver is reduced by 5-10 mg. Meanwhile, the performances of the battery and the component such as quality, reliability and the like are effectively improved.

Drawings

FIG. 1 is a schematic structural diagram of a front electrode of the present invention;

FIG. 2 is a partially enlarged schematic view of the front electrode of the present invention;

FIG. 3 is a front electrode current collection flow diagram of the present invention;

FIG. 4 is a diagram of a back electrode of the present invention;

FIG. 5 is a schematic enlarged view of a portion of the back side main gate electrode of the present invention;

FIG. 6 is a current collection flow diagram for the back electrode of the present invention;

FIG. 7 is a front and back electrode stitch bonding diagram of the present invention.

In the figure: 1. a front main grid; 101. a front thin main grid; 102. the front surface is provided with large welding spots; 103. small welding spots on the front surface; 2. a front side sub-grid; 201. a first sub-gate; 202. a second sub-gate; 3. preventing the grid line from being broken; 4. a silver main gate electrode; 401. a silver fine main grid; 402. back side small welding spots; 403. back large welding spots; 5. an aluminum main grid; 6. and (4) an aluminum auxiliary grid.

Detailed Description

The efficient laminated solar cell is formed by sequentially welding a plurality of laminated cell sheets in a superposition manner, wherein the front surface of each laminated cell sheet is provided with a front electrode, the back surface of each laminated cell sheet is provided with a back electrode, the front electrode and the back electrode are respectively positioned at two opposite sides of the front surface and the back surface of each laminated cell sheet, and the adjacent laminated cell sheets are connected with each other through the front electrode and the back electrode in a superposition manner.

Specifically, as shown in fig. 1, the front electrode of the present invention includes a front main grid 1 and a plurality of front sub-grids 2 located on one side of the front main grid 1, vertically connected to the front main grid 1, and spaced apart from each other. The front-side main grid 1 is formed by combining welding points and thin main grids, specifically, the front-side main grid 1 is formed by a plurality of welding points which are distributed at intervals and thin main grids 101 which are connected between the adjacent welding points, wherein the distribution positions of the welding points respectively correspond to each front-side auxiliary grid 2. Through adopting the solder joint stitch welding mode to replace current hollow out construction design to realize anodal electrically conductive being connected with the negative pole between the shingled battery piece to can reduce the consumption of main grid thick liquids on effective welding area's basis, and can reduce contact resistance under the unchangeable condition of silver thick liquids consumption, thereby improve current collection efficiency.

As shown in fig. 2, the pads are composed of front large pads 102 and front small pads 103 with different sizes, the number of the front large pads 102 on each front main gate 1 is 8-20, the rest are small pads, the front sub-gate 2 is composed of a first sub-gate 201 and a second sub-gate 202, wherein the first sub-gate 201 corresponds to the front small pads 103, the second sub-gate 202 corresponds to the front large pads 102, and the width of the second sub-gate 202 is 1.5-10 times the width of the first sub-gate 201. The shape of the welding spot is composed of polygons such as a square and a trapezoid, preferably a trapezoid figure, wherein the figure length of the small welding spot 103 on the front side of the trapezoid is 0.2-1.0mm, the width of the short side is 0.05-1.0mm, and the width of the long side is 0.2-1.5 mm; the pattern length of the large welding points 102 on the front surface of the trapezoid is 0.4-1.5mm, the width of the short side is 0.2-1.5mm, and the width of the long side is 0.3-2.0 mm.

Two continuous breakage-proof grid lines 3 perpendicular to the front side auxiliary grids 2 are arranged between the front side auxiliary grids 2, and the width of each breakage-proof grid line 3 is 1.2-2 times of the line width of each front side auxiliary grid 2. With reference to fig. 3, a part of the current collected by the front side sub-grid 2 is directly transmitted to the welding point of the front side main grid 1 for exporting; one part of the grid line 3 is transmitted to the auxiliary grid connected with the front large welding point 102 through the anti-breaking grid line and then transmitted to the front large welding point 102 to be led out, so that the current collection efficiency is obviously improved.

The thin main grid 101 is composed of a rectangle or an S curve, preferably a rectangle, and the width of the thin main grid is 0.01-0.2 mm; the front side auxiliary grid 2 adopts a gradual change design with 2-10 sections, preferably a four-section bamboo joint gradual change design, the width difference of each section of grid line is 2-10 mu m, and the length of each section is increased along with the reduction of the width of the line width; the distance between the adjacent front auxiliary grids 2 is 1.00-1.32 mm.

With reference to fig. 4-6, the back electrode of the present invention is composed of a silver main grid electrode 4 and an aluminum electrode, the silver main grid electrode 4 is designed by a solder joint + fine main grid structure similar to the front main grid 1, specifically, the silver main grid electrode 4 is composed of a plurality of solder joints distributed at intervals and a silver fine main grid 401 connected between adjacent solder joints, and the solder joints are composed of a back small solder joint 402 and a back large solder joint 403 corresponding to the number and position of the solder joints on the front main grid 1. 8-20 uniformly distributed back large welding spots 403 are set on each back silver main grid electrode 4, and the rest are small welding spots; the welding spots are composed of polygons such as squares and trapezoids, wherein the graph of the small welding spot 402 on the back surface is preferably square, and the side length of the graph is 0.4-1.2 mm; the pattern of the large back pad 403 is preferably rectangular, with a pattern length of 1.2-2.5mm and a pattern width of 0.5-2.2 mm.

The silver main grid electrode 4 is connected with the aluminum electrode through a large back welding point 403, and the silver fine main grid 401 is formed by a rectangle or an S curve, and the like, preferably a rectangle, and the width of the silver fine main grid is 0.05-0.5 mm. The aluminum electrode is composed of an aluminum main grid 5 and an aluminum auxiliary grid 6, the aluminum auxiliary grid 6 is distributed on one side of the aluminum main grid 5 at intervals and is vertically connected with the aluminum main grid 5, and the other side of the aluminum main grid 5 is connected with a back large welding point 403.

(1) The utility model relates to a front electrode pattern printing process: and a screen printing technology of a mesh-free screen plate is adopted. Specifically, the screen plate removes steel wires parallel to the front side auxiliary grid in the front side electrode auxiliary grid area by adopting a laser cutting wire removing mode and the like, and eliminates the net knots formed by longitudinal and transverse steel wires of the steel wire net originally existing in the auxiliary grid area. Therefore, the design line width of the front side sub-grid can be reduced to 10-26 mu m, the reduction of the shading area and the reduction of silver paste consumption are realized, and meanwhile, printing conditions are provided for a dense-grid high-resistance technical route. Meanwhile, a high-precision screen printing mode is adopted to print the front main grid and the front auxiliary grid in a grading manner; the method comprises the steps of firstly, adopting a mode of welding spots of a main grid, a mode of fine main grid and a mode of secondary grid in the process of printing in a grading mode; adopting a mesh-free screen plate when only the front auxiliary grid is subjected to screen printing; the front main grid is matched with high printing flatness, solderability and non-burn-through type front silver paste, so that the metallization composition of a main grid region can be reduced, and the assembly welding performance of the main grid is improved, such as polymerization M3M-FB 07-6. The front side sub-grid is matched with the front silver paste of the mesh-free screen plate, the height-width ratio is better, and the burn-through type front silver paste (such as polymerized CSP-M3D-S6009V258S) ensures that the shading area is reduced, and excellent metallization and carrier collection are realized. Therefore, the distance between the sub-grids is reduced to 1.00-1.32mm, and the square resistance of the diffusion 155 and the square resistance of the diffusion 250 omega/□ are matched, so that the conversion efficiency of the laminated cell can be improved.

By adopting the non-mesh technology and the step-by-step printing mode for the auxiliary grid, the problems of poor ink permeability of the front silver paste and fluctuation of the grid line appearance caused by the mesh of the steel wire are solved, the limitation of the auxiliary grid paste on the requirements of the tension and the welding performance of the main grid area is broken through, the metallization performance of the auxiliary grid area is improved, the designed line width can be reduced to 10-26 mu m, and further the reduction of the shading area and the reduction of the silver paste consumption are realized.

(2) And (3) imbricating and welding: as shown in fig. 7, the laminated cell is cut in the direction parallel to the main grids of the front and back electrodes, and the front main grid electrode and the back main grid electrode are welded in an overlapped manner during welding, so that the maximum welding area is ensured due to the overlapping positions of the welding points of the front main grid and the back main grid.

Through the technical route, the photoelectric conversion efficiency of the laminated PERC cell can be improved by over 0.1 percent, the consumption of front silver is reduced by 20mg, and the consumption of back silver is reduced by 5-10 mg. Meanwhile, the performances of the battery and the component such as quality, reliability and the like are effectively improved.

The utility model is further described with reference to specific examples.

Example 1

In the high-efficiency tiled solar cell of the embodiment, the front electrode of each tiled cell consists of a front main grid 1 and front auxiliary grids 2 which are vertically connected with the front main grid 1 and are uniformly and alternately distributed (the front main grid 1 is positioned on one side of the cell). The front main grid 1 adopts a main grid welding point and a thin main grid, the main grid welding points comprise front large welding points 102 and front small welding points 103, the number of the front large welding points 102 on each front main grid 1 is 12 in the embodiment, the rest are the small welding points, the small welding points and the large welding points adopt trapezoidal patterns, the length (the height of the trapezoid, namely the extending length of the welding points along the direction of the auxiliary grid) of the small welding points is 0.6mm, the width of the short side is 0.3mm, the width of the long side is 0.6mm, the length of the large welding points is 0.8mm, the width of the short side is 0.5mm, and the width of the long side is 1.0 mm. The adjacent welding points are connected through a thin main grid 101, the thin main grid is formed by rectangles, and the width of the thin main grid is 0.1 mm.

One end of the front side auxiliary grid 2 is respectively connected to each welding point on the front side main grid 1, in the embodiment, the auxiliary grid adopts a four-section bamboo joint gradual change design, and the width of each section of grid line is 22, 24, 26 and 28 micrometers respectively; the length ratio of each corresponding segment is 4: 3: 2: 1. the distance between the grid lines of the auxiliary grid is 1.22 mm; two continuous anti-breaking grid lines 3 are arranged between the auxiliary grids, the width of the grid lines is respectively 30 mu m and 36 mu m, and the width of the anti-breaking grid line close to the main grid is wider.

The back electrode of each laminated cell consists of a silver main grid electrode 4 and an aluminum electrode, specifically, in this embodiment, the silver main grid electrode 4 adopts a welding point + silver fine main grid structural design similar to the front main grid 1 (the number and the distribution positions of the back small welding points 402 and the back large welding points 403 are both corresponding to the front main grid), wherein the back small welding points 402 adopt a square shape, and the side length of the square shape is 0.8 mm. The back large solder joint 403 is in a rectangular pattern with a length of 1.7mm and a width of 1.2 mm. The silver main grid electrode 4 is connected with the aluminum electrode through a large back welding point 403, and the silver fine main grid 401 is formed by a rectangle, and the width of the silver fine main grid is 0.3 mm.

The manufacturing method of the high-efficiency shingled solar cell of the embodiment specifically comprises the following steps:

1. texturing: a monocrystal P-type silicon wafer is adopted, and front and back texturing is carried out by alkali to form a textured structure.

2. Diffusion: and (3) reacting the textured silicon wafer with phosphorus oxychloride at high temperature to diffuse the front surface to form a PN emitter junction, wherein the sheet resistance of the front surface thin layer after diffusion is 160 omega/□.

3. Laser SE: and performing laser doping on the front surface of the diffused silicon wafer and the metalized area corresponding to the front electrode grid line by using the diffused phosphorosilicate glass as a phosphorus source to form a heavily doped area, thereby realizing the structure of selecting the emitter on the front surface of the silicon wafer. The square resistance of the heavily doped region is 70 omega/□, and the laser SE is only doped at the secondary grid of the positive electrode pattern.

4. Thermal oxidation: and introducing oxygen into the silicon wafer subjected to the laser SE for oxidation.

5. Removing PSG: and removing the PSG on the back and the periphery of the silicon wafer after thermal oxidation by using HF.

6. Alkali polishing: and polishing the back and the edge of the silicon wafer after the PSG is removed, and removing the PSG on the front side.

7. Oxidizing and annealing: and carrying out oxidation and annealing treatment on the silicon wafer subjected to alkali polishing.

8. Depositing a passivation film on the back: and preparing a passivation film on the back of the annealed silicon wafer.

9. Front side deposition of an antireflection film: and preparing a passivation and antireflection layer on the front side of the silicon wafer.

10. Back laser: and carrying out laser drilling on the silicon wafer with the passivation film prepared on the back surface.

11. Printing a back silver electrode: and (3) preparing a back silver electrode (a silver main gate electrode 4) on the silicon wafer with the back surface subjected to laser hole opening through screen printing.

12. Back aluminum electrode printing: and screen printing a back aluminum electrode on the silicon wafer printed with the back silver electrode.

13. Printing a positive electrode main gate region: the front main grid 1 is prepared by screen printing on a silicon wafer printed with a back aluminum grid line by adopting a front silver paste (polymerized M3M-FB07-6 in the embodiment) with high solid content, high solderability and no burn-through of silicon nitride.

14. Printing a positive electrode secondary grid region: the front side sub-grid 2 is prepared by screen printing on a silicon wafer printed with a positive electrode main grid by adopting a non-mesh-junction screen plate and non-mesh-junction positive silver paste (the embodiment adopts polymerized CSP-M3D-S6009V258S) which is matched with silicon nitride and has a high aspect ratio and is burnt through.

15. And (3) sintering: the silicon wafer with the front electrode printed is co-sintered, and the sintering peak temperature can be selected within 800 ℃ of 720-.

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

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

Example 2

The high-efficiency shingled solar cell of the present embodiment has a structure substantially the same as that of embodiment 1, and the difference is mainly that: in this embodiment, the number of the front large solder joints 102 on each front main grid 1 is 8, the rest are small solder joints, the length of the small solder joints is 0.2mm, the width of the short side is 0.1mm, the width of the long side is 0.2mm, the length of the large solder joints is 0.4mm, the width of the short side is 0.2mm, and the width of the long side is 0.3 mm. The width of the thin main gate 101 between adjacent pads is 0.07 mm.

In the embodiment, the auxiliary grid adopts a 3-section bamboo joint gradual change design, and the width of each section of grid line is 20, 25 and 30 micrometers respectively; the length ratio of each corresponding segment is 4: 3: 2. the distance between the grid lines of the auxiliary grid is 1.32 mm; the widths of the two breaking-preventing gate lines 3 between the sub-gates are 37 μm and 42 μm, respectively. The small welding points 402 on the back surface of the back electrode of the laminated cell sheet are in a square shape, and the side length of the square shape is 0.4 mm. The back large welding point 403 adopts a rectangular pattern, the length of the back large welding point is 1.2mm, the width of the back large welding point is 0.5mm, and the width of the silver fine main grid 401 is 0.3 mm.

2. Diffusion: and (3) reacting the textured silicon wafer with phosphorus oxychloride at high temperature to diffuse the front surface to form a PN emitter junction, wherein the sheet resistance of the front surface thin layer after diffusion is 170 omega/□.

3. Laser SE: and performing laser doping on the front surface of the diffused silicon wafer and the metalized area corresponding to the front electrode grid line by using the diffused phosphorosilicate glass as a phosphorus source to form a heavily doped area, thereby realizing the structure of selecting the emitter on the front surface of the silicon wafer. The square resistance of the heavily doped region is between 80 omega/□, and the laser SE is only doped at the secondary grid of the positive electrode pattern.

15. And (3) sintering: and (3) co-sintering the silicon chip with the front electrode printed, wherein the sintering peak temperature is 720 ℃.

Example 3

The high-efficiency shingled solar cell of the present embodiment has a structure substantially the same as that of embodiment 1, and the difference is mainly that: in this embodiment, the number of the front large solder joints 102 on each front main grid 1 is 20, the rest are small solder joints, the length of the small solder joints is 1.0mm, the width of the short side is 1.0mm, the width of the long side is 1.5mm, the length of the large solder joints is 1.5mm, the width of the short side is 1.5mm, and the width of the long side is 2.0 mm. The width of the thin main gate 101 between adjacent pads is 0.2 mm.

In the embodiment, the distance between the auxiliary grid lines is 1.0 mm; the widths of the two anti-breaking grid lines 3 between the auxiliary grids are 34 mu m and 38 mu m respectively. The small welding points 402 on the back surface of the back electrode of the laminated cell sheet are in a square shape, and the side length of the small welding points is 1.2 mm. The back large welding point 403 adopts a rectangular pattern, the length of the back large welding point is 2.5mm, the width of the back large welding point is 2.2mm, and the width of the silver fine main grid 401 is 0.5 mm.

2. Diffusion: and (3) reacting the textured silicon wafer with phosphorus oxychloride at high temperature to diffuse the front surface to form a PN emitter junction, wherein the sheet resistance of the front surface thin layer after diffusion is 168 omega/□.

3. Laser SE: and performing laser doping on the front surface of the diffused silicon wafer and the metalized area corresponding to the front electrode grid line by using the diffused phosphorosilicate glass as a phosphorus source to form a heavily doped area, thereby realizing the structure of selecting the emitter on the front surface of the silicon wafer. The sheet resistance of the heavily doped region is between 73 omega/□, and the laser SE is only doped at the secondary grid of the positive electrode pattern.

15. And (3) sintering: and (3) co-sintering the silicon wafer with the front electrode printed, wherein the sintering peak temperature is 780 ℃.

Example 4

The high-efficiency shingled solar cell of the present embodiment has a structure substantially the same as that of embodiment 1, and the difference is mainly that: in this embodiment, the number of the large front-side solder joints 102 on each front-side main grid 1 is 14, the rest are small solder joints, the small solder joints are square, the side length is 1.3mm, the large solder joints are rectangular, the length is 1.8mm, and the width is 1.5 mm. The thin main gate 101 between adjacent pads is S-shaped with a width of 0.15 mm.

In the embodiment, the auxiliary grid adopts a five-section bamboo joint gradual change design, and the grid line spacing of the auxiliary grid is 1.1 mm; the widths of the two breakage preventing gate lines 3 between the sub-gates are 30 μm and 33 μm, respectively. The small welding points 402 on the back surface of the back electrode of the laminated cell sheet are in a rectangular shape, the length of the small welding points is 1.5mm, and the width of the small welding points is 1.3 mm. The back large welding point 403 is in a trapezoid shape, the length of the back large welding point is 2.0mm, the width of the short side is 1.3mm, the width of the long side is 1.8mm, the silver thin main grid 401 is in an S curve shape, and the width of the silver thin main grid is 0.4 mm.

2. Diffusion: and (3) reacting the textured silicon wafer with phosphorus oxychloride at high temperature to diffuse the front surface to form a PN emitter junction, wherein the sheet resistance of the front surface thin layer after diffusion is 162 omega/□.

3. Laser SE: and performing laser doping on the front surface of the diffused silicon wafer and the metalized area corresponding to the front electrode grid line by using the diffused phosphorosilicate glass as a phosphorus source to form a heavily doped area, thereby realizing the structure of selecting the emitter on the front surface of the silicon wafer. The square resistance of the heavily doped region is 65 omega/□, and the laser SE is only doped at the secondary grid of the positive electrode pattern.

15. And (3) sintering: and (3) co-sintering the silicon chip with the front electrode printed, wherein the sintering peak temperature is 800 ℃.

Claims

1. The utility model provides a high-efficient shingled solar cell's positive electrode, includes positive main grid (1) and a plurality of positive auxiliary grid (2) that link to each other and interval distribution perpendicularly with positive main grid (1), its characterized in that: the front-side main grid (1) is composed of a plurality of welding points which are distributed at intervals and thin main grids (101) which are connected between the adjacent welding points, wherein the distribution positions of the welding points respectively correspond to each front-side auxiliary grid (2).

2. The front electrode of a high efficiency shingled solar cell as recited in claim 1, wherein: the welding spots on the front main grid (1) are composed of front large welding spots (102) and front small welding spots (103) with different sizes.

3. The front electrode of a high efficiency shingled solar cell as recited in claim 2, wherein: the number of the front large welding points (102) is 8-20.

4. The front electrode of a high efficiency shingled solar cell as recited in claim 2, wherein: the front large welding points (102) and the front small welding points (103) are polygonal in shape.

5. The front electrode of a high efficiency shingled solar cell as recited in claim 2, wherein: the shapes of the front large welding points (102) and the front small welding points (103) are both trapezoidal, wherein the graphic length of the trapezoidal front small welding points (103) is 0.2-1.0mm, the width of the short side is 0.05-1.0mm, and the width of the long side is 0.2-1.5 mm; the pattern length of the big welding points (102) on the front surface of the trapezoid is 0.4-1.5mm, the width of the short side is 0.2-1.5mm, and the width of the long side is 0.3-2.0 mm.

6. The front electrode of a high efficiency shingled solar cell as recited in claim 2, wherein: the front side sub-grid (2) is composed of a first sub-grid (201) and a second sub-grid (202), wherein the first sub-grid (201) corresponds to the front side small welding point (103), the second sub-grid (202) corresponds to the front side large welding point (102), and the width of the second sub-grid (202) is 1.5-10 times of the width of the first sub-grid (201).

7. The front side electrode of a high efficiency shingled solar cell according to any of claims 1-6, wherein: two continuous anti-breaking grid lines (3) which are vertical to the front auxiliary grids (2) are arranged between the front auxiliary grids (2).

8. The front electrode of a high efficiency shingled solar cell according to claim 7, wherein: the width of the breakage-proof grid line (3) is 1.2-2 times of the line width of the front auxiliary grid (2).

9. The front side electrode of a high efficiency shingled solar cell according to any of claims 1-6, wherein: the thin main grid (101) is composed of a rectangle or an S curve.

10. The front electrode of a high efficiency shingled solar cell as defined by claim 9 wherein: the thin main grid (101) is formed by a rectangle, and the width of the thin main grid is 0.01-0.2 mm.

11. The front side electrode of a high efficiency shingled solar cell according to any of claims 1-6, wherein: the front side auxiliary grids (2) adopt a gradual change design with 2-10 sections, and the distance between the adjacent front side auxiliary grids (2) is 1.00-1.32 mm.

12. The front electrode of a high efficiency shingled solar cell as defined by claim 11 wherein: the front side auxiliary grid (2) adopts a four-section bamboo joint gradual change design, the width difference of each section of grid line is 2-10 mu m, and the length of each section is increased along with the reduction of the width of the line width.

13. The utility model provides a high-efficient shingled solar cell, this solar cell forms its characterized in that by a plurality of shingled battery piece stitch welding in proper order: the front side of each of the shingled cells is provided with a front electrode as recited in any of claims 1-12.

14. A high efficiency shingled solar cell as defined by claim 13 wherein: the back of each laminated cell is provided with a back electrode, the front electrode and the back electrode are respectively positioned at two opposite sides of the front and back of the laminated cell, and the adjacent laminated cells are connected with each other by stitch welding of the front electrode and the back electrode.

15. A high efficiency shingled solar cell as defined by claim 14 wherein: the back electrode is composed of a silver main grid electrode (4) and an aluminum electrode, the aluminum electrode is electrically connected with the silver main grid electrode (4), the silver main grid electrode (4) is composed of a plurality of welding points which are distributed at intervals and a silver fine main grid (401) which is connected between the adjacent welding points, and the welding points are composed of back small welding points (402) and back large welding points (403) which respectively correspond to the number and the positions of the welding points on the front main grid (1).

16. A high efficiency shingled solar cell as defined by claim 15 wherein: the pattern of the small welding spot (402) on the back surface is square, and the side length of the pattern is 0.4-1.2 mm; the pattern of the back large welding spot (403) is rectangular, the length of the pattern is 1.2-2.5mm, and the width of the pattern is 0.5-2.2 mm.

17. A high efficiency shingled solar cell as defined by claim 16 wherein: the silver thin main grid (401) is rectangular, and the width of the silver thin main grid is 0.05-0.5 mm.

18. A high efficiency shingled solar cell according to any of claims 15-17 wherein: the silver main grid electrode (4) is connected with the aluminum electrode through a back large welding point (403).

19. A high efficiency shingled solar cell as defined by claim 18 wherein: the aluminum electrode is composed of an aluminum main grid (5) and an aluminum auxiliary grid (6), the aluminum auxiliary grid (6) is distributed on one side of the aluminum main grid (5) at intervals and is vertically connected with the aluminum main grid (5), and the other side of the aluminum main grid (5) is connected with a back large welding point (403).