CN212161825U

CN212161825U - Back contact solar cell module

Info

Publication number: CN212161825U
Application number: CN202020863690.4U
Authority: CN
Inventors: 汤坤; 蒋秀林; 吴兰峰
Original assignee: Ja Solar Co Ltd; JA Solar Technology Yangzhou Co Ltd
Current assignee: JA Solar Technology Yangzhou Co Ltd; Jingao Solar Co Ltd
Priority date: 2020-05-21
Filing date: 2020-05-21
Publication date: 2020-12-15
Anticipated expiration: 2030-05-21

Abstract

The utility model discloses a back contact solar cell module, which comprises N small cell pieces and (N-1) conductive bars, wherein a p + doping area of each small cell piece is provided with an anode thin grid line, a N + doping area is provided with a cathode thin grid line, and each small cell piece is not provided with a main grid line for collecting currents of the N + doping area and the p + doping area; the conductive strips comprise substrates and conductive patterns arranged on the substrates, each substrate is arranged between two adjacent small battery pieces, and the conductive patterns are used for electrically connecting the fine grid lines with opposite polarities on the two adjacent small battery pieces at intervals in sequence so as to connect the small battery pieces in series. The utility model provides a have higher efficiency stability, and the resistance loss on the silver grid line is low, and the fill factor of subassembly is high, can also greatly simplify back of the body contact solar module's manufacturing process simultaneously, reduces the manufacturing cost of battery.

Description

Back contact solar cell module

Technical Field

The utility model relates to a solar cell produces technical field, especially relates to a back of body contact solar module.

Background

The pursuit of lower production costs and higher photoelectric conversion efficiency in the field of solar cell technology is a core goal of the solar cell industry. The all back contact solar cell is different from the conventional solar cell, and the positive and negative electrodes are arranged on the back surface of the cell, so that the optical loss similar to the front surface of the conventional solar cell is avoided, the photoelectric conversion efficiency of the cell is improved, and the all back contact solar cell is one of the cell types which are widely concerned and researched in the technical field of high-efficiency cells.

The existing full back contact solar cells are all provided with a main grid design, and the main grid has the functions of collecting current and connecting a welding strip. Since the full back contact solar cell has a higher short circuit current, the full back contact solar cell has to adopt more main gate designs to reduce power loss caused by line resistance on the main gate lines and the thin gate lines, which consumes more silver paste than the conventional solar cell. Meanwhile, because the long n + doped regions and the long p + doped regions which are arranged in parallel and the thin grid lines which are respectively connected with the n + doped regions and the p + doped regions are arranged at intervals, how to avoid the problem of battery failure caused by short circuit of the positive electrode and the negative electrode of the battery needs to be considered when designing the main grid of the battery.

At present, one method is to introduce extra insulating materials and process steps to realize that the positive and negative main grids are only connected with the fine grid lines with the same polarity, but the method has the problems of complex process, high battery manufacturing cost, low battery efficiency and low stability of component power, and component power is further reduced and even electrical safety is caused in the power generation process for decades in the future. The other method is to design the positive and negative electrodes in a shape of Chinese character feng, the thin grid line of the negative electrode avoids the main grid line of the positive electrode, and the thin grid line of the positive electrode avoids the main grid line of the negative electrode. Therefore, the two-dimensional patterns of the positive electrode and the negative electrode have no staggered position, so that the problem of reverse electric leakage is solved. However, in this design, the carrier transverse transmission distance is too long, and the carrier is difficult to be collected by the thin grid lines with positive and negative polarities, so that the series resistance of the battery can be rapidly increased, and the battery filling factor and the photoelectric conversion efficiency can be greatly influenced.

In addition, in the manufacturing process of the traditional full back contact solar cell module with the main grid designed on the front surface, the problem that the silicon wafer is warped and uneven due to a large amount of welding strips, so that hidden cracks or fragments are generated in the cell module, or the problem that the precision control difficulty and the manufacturing cost are increased due to the integrally-formed back plate design is also solved. Therefore, how to simplify the manufacturing process of the all back contact solar cell module and mass-produce the all back contact solar cell module which has stable performance and is accepted by the market is a problem to be solved urgently.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to overcome the defect among the prior art to a back of body contact solar module is provided, this back of body contact solar module has higher efficiency stability, and the resistive loss on the silver grid line is low, and the fill factor of subassembly is high.

In order to achieve the above object, the present invention provides the following technical solutions:

a back contact solar cell module comprising:

the back of each small cell piece is provided with a p + doping region and an N + doping region which are arranged in a staggered mode, the p + doping region of each small cell piece is provided with an anode thin grid line, the N + doping region of each small cell piece is provided with a cathode thin grid line, and each small cell piece is not provided with a main grid line for collecting currents of the N + doping region and the p + doping region;

(N-1) conducting strips, each conducting strip comprises a substrate and conducting patterns arranged on the substrate, each substrate is arranged between two adjacent small battery pieces, and the conducting patterns are used for electrically connecting the fine grid lines with opposite polarities on the two adjacent small battery pieces at intervals in sequence so as to connect the small battery pieces in series.

In one embodiment, the small cell piece is formed by cutting a whole back contact solar cell piece, the back contact solar cell piece is provided with p + doped regions and n + doped regions which are arranged in a staggered mode, and the cutting direction is parallel to the short sides of the p + doped regions or the n + doped regions.

In one embodiment, preferably, the p + doped region and the n + doped region are both arranged to penetrate through the short side of the small cell, and the lengths of the positive fine grid line and the negative fine grid line are both set to be infinitely close to the width of the small cell, so that all currents in the area range of the cell can be collected as much as possible, the fine grid lines cannot contact with the edge of the cell, and the occurrence of electric leakage can be prevented.

In one embodiment, the substrate has a coefficient of expansion close to that of silicon, and the conductive pattern is formed of solder or conductive paste.

In one embodiment, the substrate is a conductive silicon wafer. Preferably, the conductive silicon wafer has a plated film or has a high resistivity to allow the conductive silicon wafer to have a better insulating property.

In one embodiment, the n + doped regions and the p + doped regions on two adjacent small battery pieces are arranged in a one-to-one correspondence manner, and the conductive pattern of the conductive strip is formed by arranging a plurality of conductive folding lines in rows, wherein the conductive folding lines are in a step shape.

In one embodiment, the n + doped regions and the p + doped regions on two adjacent small battery pieces are arranged in a staggered and corresponding manner, and the conductive pattern of the conductive strips is formed by arranging a plurality of straight lines in a row.

In one embodiment, the n + doped region and the p + doped region are each rectangular strips of equal width. In one embodiment, the n + doped region is in a strip shape and comprises wide rectangular strips and narrow rectangular strips which are arranged in a staggered mode; the p + doped region is filled between two adjacent n + doped regions.

A method of making a back contact solar cell module, comprising the steps of:

(1) cutting back contact battery pieces at equal intervals along the short side direction of the n + doped region or the p + doped region to obtain a plurality of small battery pieces;

(2) arranging conductive patterns on a substrate to form conductive strips, and sequentially connecting the small battery pieces in series through the conductive strips to form a battery string;

(3) and sequentially converging, laminating and laminating the cell strings to carry out packaging to obtain the back contact solar cell module.

In one embodiment, the number of small battery pieces in step (1) is N, and 2 ≦ N ≦ 20. In this embodiment, the number of the small battery pieces is not greater than 20, because if the number of the divided small battery pieces is larger, the width of the conductive silicon chip adapted to the small battery pieces is narrower, and if the width of the conductive silicon chip is too narrow, the conductive strips cannot be printed and the subsequent production cannot be continued.

In one embodiment, in the step (2), the conductive pattern is dried and cured on the substrate by solder or conductive adhesive in a printing manner, and the drying and curing temperature is 100-500 ℃ for 30-600 s. Drying and curing are carried out under the conditions of the soldering tin and the conductive adhesive, so that falling off or damage to conductivity can be avoided.

In one embodiment, the solder is tin, a tin-lead alloy, a tin-bismuth alloy, or a tin-lead-silver alloy; the conductive adhesive is coated with a conductive particle binder, the binder is one or more of epoxy resin, phenolic resin, polyurethane, thermoplastic resin or polyimide, and the conductive particles are silver, gold and copper or alloy particles consisting of more than two of silver, gold and copper.

Compared with the prior art, the utility model discloses following beneficial effect has:

firstly, the back contact solar cell module provided by the utility model completely abandons the design of the conventional main grid line, thereby greatly simplifying the cell manufacturing process, improving the efficiency stability of the cell and reducing the cell manufacturing cost;

secondly, the utility model adopts the conductive strip to connect each small battery piece in series, wherein the conductive strip is composed of a substrate and a conductive pattern, the substrate is a bearing plate, the conductive pattern is used for electrically connecting the fine grid lines with opposite polarities on two adjacent small battery pieces, therefore, when the small battery pieces are connected in series, only the conductive pattern and the fine grid lines with opposite polarities on the two small battery pieces are electrically connected in sequence at intervals, so that the current on the battery string is led out along the doping area of the electrical connection through the conductive pattern, thus, when the small battery pieces are produced, the small battery pieces are not limited by the limitation of the current collection area design of the main grid lines (for example, although the positive electrode fine grid and the negative electrode fine grid are parallel to each other and are alternately arranged, the two ends of the positive electrode fine grid and the two ends of the negative electrode fine grid are not required to be arranged in alignment, namely, the other end of the positive electrode fine grid is provided with a shortened end and the like relative to the other end of the negative electrode fine grid), the long strip-shaped n + doping region and the long strip-shaped p + doping region in the battery can directly penetrate through the whole battery piece during production, then the battery piece is directly cut along the short side of the n + doping region or the p + doping region to form a plurality of small battery pieces, and then the small battery pieces are mutually connected into a battery string through the conducting pieces printed with specific conducting patterns.

In addition, the utility model is formed by connecting a plurality of small battery pieces in series, and compared with the whole back contact solar battery piece, the current of each battery piece group string is reduced, and the influence of resistance loss on the silver grid line is reduced, thereby improving the filling factor of the component;

in addition, the utility model discloses the base plate coefficient of expansion of conducting bar is close with silicon, perhaps can still be with the silicon chip of battery piece base member unanimity, consequently, has avoided because the condition of latent splitting or piece that the coefficient of thermal expansion is inconsistent between them leads to takes place.

Drawings

Fig. 1 is a cross-sectional view of a full back contact solar cell provided in embodiments 1-2 of the present invention;

FIG. 2 is a bottom view of FIG. 1;

fig. 3 is a small cell arranged after the full back contact solar cell is cut in example 1;

fig. 4 is a schematic structural diagram of a conductive strip according to an embodiment of the present invention;

fig. 5 is a full back contact solar cell string provided in embodiment 1 of the present invention;

fig. 6 is a small cell arranged after the full back contact solar cell is cut in example 2;

fig. 7 is a schematic structural diagram of a conductive strip according to another embodiment of the present invention;

fig. 8 is a full back contact solar cell string provided in embodiment 2 of the present invention;

fig. 9 is a schematic structural diagram of a full back contact solar cell provided in embodiments 3-4 of the present invention;

fig. 10 is a small cell arranged after the full back contact solar cell is cut in example 3;

fig. 11 is a full back contact solar cell string provided in embodiment 3 of the present invention;

fig. 12 is a small cell arranged after the full back contact solar cell is cut in example 4;

fig. 13 is a full back contact solar cell string provided in embodiment 4 of the present invention;

description of reference numerals:

1. a silicon substrate; 2. a p + doped region; 21. a positive electrode; 3. an n + doped region; 31. a negative electrode; 4. n + Front Surface Field (FSF) of low surface doping concentration; 5. an antireflection laminated passivation film; 6. a reflection enhancing laminated passivation film; 7. a conductive strip; 71. a substrate; 72. a conductive pattern.

Detailed Description

The technical solution of the present invention will be described with reference to the accompanying drawings.

Example 1

Referring to fig. 3, fig. 3 shows small cells arranged after the full back contact solar cell is cut in example 1. The utility model provides a back contact solar module, including a plurality of little battery pieces and busbar 7, wherein, the back of every little battery piece has crisscross p + doping region 2 and the n + doping region 3 who sets up along its width direction tiling, the printing has the fine grid line of positive pole (positive electrode 21) rather than ohmic contact on the p + doping region 2, the printing has the fine grid line of negative pole (negative electrode 31) rather than ohmic contact on the n + doping region 3, the length of the fine grid line of positive pole (positive electrode 21) and the fine grid line of negative pole (negative electrode 31) infinitely approaches the width of little battery piece; referring to fig. 4, the conductive strip 7 includes a substrate 71 and a conductive pattern 72 disposed on the substrate 71, referring to fig. 5, the substrate 71 is disposed between two adjacent small battery pieces, and the conductive pattern 72 is used to electrically connect the fine grid lines with opposite polarities on the two adjacent small battery pieces at intervals in order to connect the small battery pieces in series, specifically, all the positive fine grid lines (positive electrodes 21) on the small battery piece relatively located on the left side are electrically connected with all the negative fine grid lines (negative electrodes 31) on the small battery piece relatively located on the right side, or all the negative fine grid lines (negative electrodes 31) on the small battery piece relatively located on the right side are electrically connected with all the positive fine grid lines (positive electrodes 21) on the small battery piece relatively located on the right side, and the small battery pieces are connected in series through the conductive strip 7.

Compared with the prior art, the back contact solar cell module provided by the utility model firstly completely abandons the design of the conventional main grid line, thereby greatly simplifying the cell manufacturing process, improving the efficiency stability of the cell and reducing the cell manufacturing cost; secondly, because the design of the current collecting region of the main grid line is not limited, the long strip-shaped n + doping region 3 and the long strip-shaped p + doping region 2 can penetrate through the whole battery piece, so that the battery manufacturing process is simplified, the capacity is improved, and the battery manufacturing cost is reduced; furthermore, the back contact solar cell module provided by the utility model is formed by connecting a plurality of small cells which are formed by cutting the whole back contact solar cell in series, thereby reducing the current of each string of cell group strings and reducing the influence of resistance loss on the silver grid line, thereby improving the filling factor of the module; finally, the whole back contact solar cell module uses no solder strip except for the confluence region of the cell string, and no solder strip is designed at other places, so that the module cost is greatly reduced; moreover, through the utility model discloses people's many times test verification, the subassembly electric current is in the transmission course between adjacent back of the body contact solar energy small cell piece, with the utility model discloses shown transmission path resistance is minimum, has reduced the influence of resistance loss on the silver-colored grating line to the fill factor of subassembly has been improved.

In order to avoid the situation of hidden cracks or fragments caused by the fact that the thermal expansion coefficients of the substrate 71 in the conductive strip 7 and the silicon substrate 1 of the battery piece are different, in the embodiment, the thermal expansion coefficient of the substrate 71 of the conductive strip 7 is set to be close to that of silicon, and certainly, a conductive silicon chip which is the same as the silicon substrate 1 of the battery piece can be used, and the conductive silicon chip is preferably provided with a plated film or a conductive silicon chip with high resistivity is selected, so that the electrical contact between the conductive silicon chip and the battery piece can be effectively reduced. The conductive pattern 72 is formed by solder or conductive adhesive, and the solder can be tin, tin-lead alloy, tin-bismuth alloy or tin-lead-silver alloy; the conductive adhesive is coated with a conductive particle binder, the binder can be one or more of epoxy resin, phenolic resin, polyurethane, thermoplastic resin or polyimide, and the conductive particles can be silver, gold, copper or alloy particles consisting of more than two of silver, gold and copper.

In this embodiment, the n + doped region 3 and the p + doped region 2 of the back contact solar cell module are both rectangular strips with equal width, the n + doped region 3 and the p + doped region 2 on two adjacent small cells are arranged in a one-to-one correspondence, the conductive pattern 72 of the conductive strip 7 is composed of a plurality of conductive folding lines arranged in a row along the length direction of the rectangular strips, and the conductive folding lines are in a step shape.

The preparation method of the back contact solar cell module in the embodiment comprises the following steps:

(1) preparing a back contact cell:

referring to FIG. 1, an n-type single crystal silicon substrate 1 having a resistivity of 1 to 30. omega. cm, a thickness of 50 to 300 μm and a length of 156.75mm is selected. Before the n-type monocrystalline silicon substrate 1 is used, surface texturing processing is carried out, then p + doped regions 2 and n + doped regions 3 which are alternately arranged are manufactured on the back surface of the n-type monocrystalline silicon substrate 1 by utilizing the technologies of diffusion, laser drilling, ion implantation, annealing, masking, etching and the like, and an n + Front Surface Field (FSF)4 with low surface doping concentration is manufactured on the front surface of the n-type monocrystalline silicon substrate 1. Referring to fig. 2, the p + doped region 2 is as long as the n-type single crystal silicon substrate 1, 156.75mm in width W1 of 9.8mm, and the n + doped region 3 is also as long as the n-type single crystal silicon substrate 1, 156.75mm in width W2 of 9.8 mm.

Continuing with FIG. 1, an anti-reflective stack passivation film 5 is deposited on the front surface to passivate a low surface doping concentration n + Front Surface Field (FSF)4, such as Al₂O₃/SiN_x、SiO₂/SiN_x、SiO₂/Al₂O₃/SiN_xEtc. here, SiO is selected₂/SiN_xThe film thickness of the front passivation film is 60-200 nm, the back surface is deposited with a reflection-increasing laminated passivation film 6 to perform regional passivation or simultaneous passivation on the n + doped region 3 and the P + doped region 2, and the reflection-increasing laminated passivation film 6 can be Al₂O₃/SiN_x、SiO₂/SiN_x、SiO₂/SiCN、SiO₂SiON, etc., from SiO₂/Al₂O₃/SiN_xThe thickness of the back surface passivation film was 100 nm.

With reference to fig. 1 and fig. 2, a positive electrode 21 formed by a positive fine grid line is formed on the p + doped region 2, a negative electrode 31 formed by a negative fine grid line is formed on the n + doped region 3, and the positive electrode 21 and the negative electrode 31 may be formed by printing silver paste to directly burn through the back reflection-enhanced stacked passivation film 6, or by printing or electroplating metal after laser opening, so as to form ohmic contact between the electrode and the n-type monocrystalline silicon substrate 1 and lead out current. Referring to fig. 2, the positive electrode 21 and the negative electrode 31 are equal to the p + doped region 2, the n + doped region 3 and the n-type single crystal silicon substrate 1, and are 156.75mm long, the width W3 of the positive electrode 13 is 100 μm, the width W4 of the negative electrode 43 is 100 μm, and the positive fine grid lines and the negative fine grid lines are arranged in an interdigitated manner.

(2) Preparation of Small cell pieces

Referring to fig. 3, the back contact solar cell is cut into four small back contact solar cells, and the width L11 of each small back contact solar cell is 39.1875 mm. The n + doping regions 3 and the p + doping regions 2 on the four back-contact solar cells are arranged in a one-to-one correspondence mode, and the directions of all the back-contact solar cells are consistent with those of the original back-contact solar cells. The back surface of the back contact solar small cell is only provided with an anode fine grid line which forms ohmic contact with the strip-shaped n + doping region 3 and a cathode fine grid line which forms ohmic contact with the p + doping region 2, and a main grid line for respectively collecting currents of the strip-shaped n + doping region 3 and the p + doping region 2 does not exist.

(3) Preparation of conductive strips 7

Referring to fig. 4, a conductive pattern 72 is disposed on a substrate 71, the conductive pattern 72 is composed of a plurality of conductive folding lines arranged in parallel along the length direction of a rectangular strip, the conductive folding lines are in a step shape, the conductive pattern 72 is dried and cured on the substrate 71 by solder or conductive adhesive in a printing manner, in this embodiment, solder is used for printing, the solder is made of tin-lead alloy, the solder is printed on the substrate 71 according to the above pattern, and is dried and cured for 2 minutes at 200 ℃.

With reference to fig. 4, in the present embodiment, the length L36 of the substrate 71 is 156.75mm, and the width L31 is 19.6 mm. The folding lines of the conductive pattern 72 are in a step shape, the width L32 of each folding line is 1.5mm, the distance L33 between two adjacent folding lines is 19.6mm, the height L34 of the step-shaped folding line is 9.8mm, and the width L35 of each step of the step-shaped folding line is 9.8 mm.

(4) Preparing battery string

Referring to fig. 5, the small back-contact solar cells are connected in series by the conductive bars 4 to form a string of the small back-contact solar cells, and the thin grid lines with opposite polarities of the adjacent small back-contact solar cells are connected to each other by the printing pattern 41 formed by the solder on the substrate 41, so as to ensure that the current on the cells is led out along the long sides of the strip-shaped n + doped region 3 and the strip-shaped p + doped region 2.

(5) Packaging and leaving factory

After the full back contact solar cell string is manufactured, the subsequent assembly packaging processes such as confluence, lamination and the like are the same as those of the conventional assembly manufacturing mode.

Example 2

Referring to fig. 8, different from embodiment 1, in this embodiment, four back contact solar cells are arranged as shown in fig. 6, that is, n + doped regions 3 and p + doped regions 2 on two adjacent cells are alternately and correspondingly arranged, and the direction of half of the back contact solar cells is opposite to that of the original back contact solar cells. The back surface of the back contact solar small cell only has silver grid lines which form ohmic contact with the strip-shaped n + doping region 3 and the strip-shaped p + doping region 2, and main grid lines which collect currents of the strip-shaped n + doping region 3 and the strip-shaped p + doping region 2 do not exist.

Referring to fig. 7, in the present embodiment, the conductive strips 7 are formed by printing conductive paste, which is silver metal particles wrapped with epoxy resin as a binder, onto a substrate 71 to form a conductive pattern 72. The shape of the conductive pattern is composed of a plurality of straight lines arranged in a row along the length direction of the rectangular strip. The conductive paste was printed on the substrate 71 in the shape described above, and dried at 200 ℃ for 2 minutes to be cured. The substrate 71 is made of conductive silicon wafer, and the length L44 of the conductive silicon wafer is 156.75mm, and the width L41 of the conductive silicon wafer is 19.6 mm. The width L42 of the parallel straight lines in the conductive pattern is 1.5mm, and the distance L43 between two adjacent straight lines is 19.6 mm.

Example 3

Unlike embodiment 1, referring to fig. 9, the p + doped region 2 and the n + doped region 3 on the n-type single crystal silicon substrate 1 have different local widths, which can be understood as: the n + doped region 3 is in a strip shape and comprises wide rectangular strips and narrow rectangular strips which are arranged in a staggered mode; the p + doped region 2 is filled between two adjacent n + doped regions 3, where the length of the n + doped region 2 is 156.75mm, the width W1 of the narrow rectangular bar in the n + doped region 2 is 9.8mm, the width W11 of the wide rectangular bar is 12.7mm, and the length W6 of the wide rectangular bar is W7 of W8 of 13.8mm, although the lengths of W5 and W9 vary from cut to cut due to the different cutting positions, but it is preferable to set the lengths of W5 and W9 as long, and in this embodiment, the length of W5 of W19 is 6.9 mm. The length of the p + doped region 3 filled between two adjacent n + doped regions 3 is 156.75mm, it can be understood that it is also formed by connecting the wide and narrow rectangular bars in a staggered manner, in this embodiment, the width W2 of the wide rectangular bar in the p + doped region 3 is 9.8mm, and the width W22 of the narrow rectangular bar is 6.9 mm.

Referring to fig. 4, in the present embodiment, the back-contact solar cell is cut into four small back-contact solar cells, and the width L21 of each small back-contact solar cell is 39.1875 mm. The four back-contact solar small cell pieces are arranged as shown in fig. 10, that is, the n + doped regions 3 and the p + doped regions 2 on two adjacent small cell pieces are arranged in a one-to-one correspondence manner; at the moment, the directions of all the small back-contact solar cells are consistent with those of the original back-contact solar cells. The back surface of the back contact solar small cell only has silver grid lines which form ohmic contact with the strip-shaped n + doping region 3 and the strip-shaped p + doping region 2, and main grid lines which collect currents of the strip-shaped n + doping region 3 and the strip-shaped p + doping region 2 do not exist.

Referring to fig. 4, the structure of the conductive strip is the same as that of embodiment 1, the conductive strip 7 is used to connect the small back-contact solar cells in this embodiment in series to form a string of the full back-contact solar cells, and the fine grid lines with opposite polarities of the adjacent small back-contact solar cells are connected to each other through the printing pattern 72 made of solder on the substrate 71, so as to ensure that the current on the cells is led out along the long side direction of the long n + doped region 3 and the long p + doped region 2. After the full back contact solar cell string is manufactured, the subsequent assembly packaging processes such as confluence, lamination and the like are the same as those of the conventional assembly manufacturing mode. The structure of the back contact solar cell module is shown in fig. 11.

Example 4

Different from example 3, the back-contact solar cell provided in example 3 is cut, and referring to fig. 12, four back-contact solar cells are formed after cutting, where the width L51 of the back-contact solar cell is 39.1875 mm. The 4 back-contact solar cells are arranged as shown in fig. 12, that is, the n + doped regions 3 and the p + doped regions 3 on two adjacent cells are alternately and correspondingly arranged, and the direction of half of the back-contact solar cells is opposite to that of the original back-contact solar cells. The back surface of the back contact solar small cell only has silver grid lines which form ohmic contact with the strip-shaped n + doping region 3 and the strip-shaped p + doping region 2, and main grid lines which collect currents of the strip-shaped n + doping region 3 and the strip-shaped p + doping region 2 do not exist.

The process of preparing the conductive strips 7 is also different, and the conductive pattern 72 on the substrate 71 is formed by printing conductive paste in this embodiment. The conductive pattern 72 of the conductive strip 7 is composed of a plurality of straight lines arranged in parallel along the length direction of the rectangular strip, and the conductive adhesive is silver metal particles wrapped by epoxy resin serving as an adhesive. The conductive paste was printed on the substrate 71 in the above-described pattern and dried at 200 c for 2 minutes to be cured. With reference to fig. 7, the substrate 71 is made of a conductive silicon wafer, the length L44 of which is 156.75mm, and the length L41 of which is 19.6 mm. The shape of the conductive pattern 72 is shown in fig. 7, where L42 is 1.5mm and L43 is 19.6 mm.

The small back-contact solar cells in this embodiment are connected in series to form a full back-contact solar cell string by using the conductive bars 7, and the thin grid lines with opposite polarities of the adjacent small back-contact solar cells are connected to each other through the in-store printing pattern 71 formed by the solder on the substrate 71, so as to ensure that the current on the cells is led out along the long side direction of the strip-shaped n + doping region 3 and the long side direction of the p + doping region 2. After the full back contact solar cell string is manufactured, the subsequent assembly packaging processes such as confluence, lamination and the like are the same as those of the conventional assembly manufacturing mode. The structure of the back contact solar cell module is shown in fig. 13.

Claims

1. A back contact solar cell module, comprising:

the back of each small cell is provided with a p + doping region (2) and an N + doping region (3) which are arranged in a staggered mode, the p + doping region (2) of each small cell is provided with a positive thin grid line, the N + doping region of each small cell is provided with a negative thin grid line, and each small cell is not provided with a main grid line for collecting currents of the N + doping region (3) and the p + doping region (2);

(N-1) conducting strips (7), each conducting strip (7) comprises a substrate (71) and conducting patterns (72) arranged on the substrate (71), each substrate (71) is arranged between two adjacent small battery pieces respectively, and the conducting patterns (72) are used for electrically connecting the fine grid lines with opposite polarities on the two adjacent small battery pieces at intervals in sequence so as to connect the small battery pieces in series.

2. The back contact solar cell module as claimed in claim 1, wherein the substrate (71) has a coefficient of expansion close to that of silicon, and the conductive pattern (72) is formed of solder or conductive paste.

3. The back contact solar cell module as claimed in claim 2, wherein the substrate (71) is a conductive silicon wafer.

4. The back-contact solar cell module as claimed in claim 1, wherein the n + doped regions (3) and the p + doped regions (2) of two adjacent small cells are arranged in a one-to-one correspondence, and the conductive pattern (72) of the conductive strip (7) is formed by arranging a plurality of conductive folding lines in a row, wherein the conductive folding lines are in a step shape.

5. The back contact solar cell module as claimed in claim 1, wherein the n + doped regions (3) and the p + doped regions (2) on two adjacent small cells are arranged in a staggered manner, and the conductive pattern (72) of the conductive strip (7) is formed by a plurality of straight lines arranged in a row.

6. Back contact solar cell module according to claim 4 or 5, the n + doped region (3) and the p + doped region (2) each being rectangular strips of equal width.

7. The back contact solar cell module as claimed in claim 4 or 5, the n + doped region (3) being strip-shaped comprising wide rectangular strips and narrow rectangular strips arranged alternately; the p + doped region (2) is filled between two adjacent n + doped regions (3).

8. The back contact solar cell device of claim 1, wherein 2 ≦ N ≦ 20.

9. The back contact solar cell module as claimed in claim 1, wherein the conductive pattern (72) is dried and cured on the substrate (71) by printing with solder or conductive paste.

10. The back contact solar cell module of claim 9, wherein the solder is tin, a tin-lead alloy, a tin-bismuth alloy, or a tin-lead-silver alloy; the conductive adhesive is coated with a conductive particle binder, the binder is one or more of epoxy resin, phenolic resin, polyurethane, thermoplastic resin or polyimide, and the conductive particles are silver, gold and copper or alloy particles consisting of more than two of silver, gold and copper.