CN217719617U

CN217719617U - Back contact cell and back contact assembly

Info

Publication number: CN217719617U
Application number: CN202221659948.4U
Authority: CN
Inventors: 关迎利; 黄世亮; 曹云成; 杜江海; 杨敬国
Original assignee: Zhejiang Jinko Solar Co Ltd; Jinko Solar Co Ltd
Current assignee: Zhejiang Jinko Solar Co Ltd; Jinko Solar Co Ltd
Priority date: 2022-06-29
Filing date: 2022-06-29
Publication date: 2022-11-01
Anticipated expiration: 2032-06-29

Abstract

The utility model discloses a back contact battery piece and a back contact component, wherein each back contact battery piece comprises a first area and a second area; the first main grid line and the second main grid line are opposite in polarity, and the third main grid line and the fourth main grid line are opposite in polarity; along a first direction, the first main grid line and the third main grid line are on the same extension line, the second main grid line and the fourth main grid line are on the same extension line, the polarity of the first main grid line is opposite to that of the third main grid line, and the polarity of the second main grid line is opposite to that of the fourth main grid line; the number of the first main grid lines and the number of the fourth main grid lines are respectively 7-13; welding spots are respectively arranged on the first main grid line, the second main grid line, the third main grid line and the fourth main grid line, and the number of the welding spots is 3-8. The back contact battery efficiency can be improved through the multi-main-grid structure, the use amount of the thin grid lines can be reduced, cost reduction and efficiency improvement are realized, and the fragments of the assembly end are improved.

Description

Back contact cell and back contact assembly

Technical Field

The utility model relates to the field of photovoltaic technology, more specifically relates to a back contact battery piece and back contact subassembly.

Background

With the continuous innovation of solar cell technology, the technology of related cells has also been remarkably developed, wherein the back contact cell has been paid more and more attention as a novel solar cell structure.

The back contact battery (IBC battery) refers to a battery without electrode on the front side, and metal grid lines of positive and negative poles are arranged on the back side of the battery in a finger-shaped crossed manner. The IBC battery is mainly characterized in that a PN junction and metal contact are both arranged on the back surface of the battery, and the front surface of the IBC battery is not influenced by shielding of a metal electrode, so that the IBC battery has higher short-circuit current Jsc, and meanwhile, wider metal grid lines can be allowed on the back surface to reduce series resistance Rs so as to improve a filling factor FF; the addition of the Front Surface Field (FSF) and the open-circuit voltage gain caused by good passivation makes the cell with the Front Surface free from shielding have high conversion efficiency and more beautiful appearance, and the assembly of the full back electrode is easier to assemble.

SUMMERY OF THE UTILITY MODEL

In view of this, the present invention provides a back contact battery, each back contact battery comprises a first region and a second region arranged in a staggered manner along a first direction, and the first direction is a direction pointing from the first region to the second region;

the grid-type display panel further comprises a first main grid line and a second main grid line which are arranged in a staggered mode along a second direction and extend along the first direction, and a third main grid line and a fourth main grid line which are arranged in a staggered mode along the second direction and extend along the first direction, wherein the first main grid line and the second main grid line are opposite in polarity, the third main grid line and the fourth main grid line are opposite in polarity, and the second direction is intersected with the first direction;

the first main gate line and the second main gate line are located in the first region, and the third main gate line and the fourth main gate line are located in the second region;

along the first direction, the first main gate line and the third main gate line are on the same extension line, and the second main gate line and the fourth main gate line are on the same extension line, wherein the first main gate line and the third main gate line have opposite polarities, and the second main gate line and the fourth main gate line have opposite polarities;

the number of the first main grid lines and the number of the fourth main grid lines are respectively 7-13;

the first main grid line, the second main grid line, the third main grid line and the fourth main grid line are respectively provided with welding spots along the first direction, and the number of the welding spots is 3-8.

Optionally, at least one of the first, second, third, and fourth bus bars has a width in the second direction of 30 μm to 60 μm.

Optionally, the display device further includes first and second thin gate lines arranged in a staggered manner along the first direction and extending along the second direction, and third and fourth thin gate lines arranged in a staggered manner along the first direction and extending along the second direction;

the first thin gate line and the second thin gate line are located in the first region, the first thin gate line is connected with the first main gate line, and the second thin gate line is connected with the second main gate line, wherein the first thin gate line and the first main gate line have the same polarity, and the second thin gate line and the second main gate line have the same polarity;

the third thin gate line and the fourth thin gate line are located in the second region, the third thin gate line is connected with the third main gate line, and the fourth thin gate line is connected with the fourth main gate line, wherein the third thin gate line and the third main gate line have the same polarity, and the fourth thin gate line and the fourth main gate line have the same polarity.

Optionally, at least one of the first thin gate line, the second thin gate line, the third thin gate line, and the fourth thin gate line has a width in the first direction of 20 μm to 40 μm.

Optionally, the main grid line adjacent to the edge of the battery parallel to the first direction is an edge main grid line, and at least one welding point on the edge main grid line is a first edge welding point;

the main grid line positioned between the two edge main grid lines is a middle main grid line, and at least one welding spot positioned on the middle main grid line is a first middle welding spot;

the area of the welding point at the first edge is larger than that of the welding point at the first middle position.

Optionally, the distance between the first edge weld point and the cell edge in the second direction is 5mm-8mm.

Optionally, along the first direction, the welding point at the head and tail end of the same main grid line is a second edge welding point, and the welding point between the two first edge welding points is a second middle welding point;

the area of the welding point at the second edge is larger than that of the welding point at the second middle part.

The utility model also discloses a back contact assembly, the back contact assembly comprises glass, a first packaging adhesive film, a back contact battery string, a second packaging adhesive film and a back plate which are sequentially arranged from top to bottom, wherein the back contact battery string consists of a plurality of back contact battery pieces;

each back contact cell comprises a first region and a second region which are arranged in a staggered mode along a first direction, wherein the first direction is a direction from the first region to the second region;

further comprising a blank area located between the first area and the second area;

the first main grid line and the second main grid line are arranged in a staggered mode along a second direction and extend along the first direction, and the third main grid line and the fourth main grid line are arranged in a staggered mode along the second direction and extend along the first direction, wherein the first main grid line and the second main grid line are opposite in polarity, the third main grid line and the fourth main grid line are opposite in polarity, and the second direction is intersected with the first direction;

welding spots are respectively arranged on the first main grid line, the second main grid line, the third main grid line and the fourth main grid line along the first direction, and the number of the welding spots is 3-8;

and in the first direction, the adjacent back contact battery pieces are connected through welding wires, and the diameter of each welding wire is 0.2-0.4mm.

Optionally, in a second direction, the diameter of the welding wire is d1, the widths of the first main gate line, the second main gate line, the third main gate line and the fourth main gate line are d2, respectively, and the width of the welding spot is d3, where d3 is greater than or equal to d1 and greater than or equal to d2.

the third thin gate line and the fourth thin gate line are located in the second region, the third thin gate line is connected with the third main gate line, and the fourth thin gate line is connected with the fourth main gate line, wherein the third thin gate line and the third main gate line have the same polarity, and the fourth thin gate line and the fourth main gate line have the same polarity;

the back contact type battery piece is characterized by further comprising an insulating glue film, wherein the insulating glue film is positioned on one side, close to the second packaging glue film, of the back contact type battery piece;

on the back contact battery piece, the insulating adhesive film is perpendicular to the first thin grid line, the second thin grid line, the third thin grid line and the fourth thin grid line, and the insulating adhesive film is overlapped with the first thin grid line, the second thin grid line, the third thin grid line and the fourth thin grid line and is not overlapped with the first main grid line, the second main grid line, the third main grid line and the fourth main grid line.

Optionally, a width of the insulating adhesive film along the first direction is d4, widths of the first thin gate line, the second thin gate line, the third thin gate line and the fourth thin gate line along the first direction are d5 respectively, a distance between the first thin gate line and the second thin gate line along the first direction, and a distance between the third thin gate line and the fourth thin gate line along the first direction are d6 respectively, where d6 > d4 > d5.

Optionally, the grammage of the first packaging adhesive film and the second packaging adhesive film is 250-350g/m²(ii) a And/or

On the back contact battery piece perpendicular to, the thickness of first encapsulation glued membrane is 0.25mm-0.4mm, and the thickness of second encapsulation glued membrane is 0.35mm-0.7mm.

Compared with the prior art, the utility model provides a back of body contact battery piece and back of body contact subassembly has realized following beneficial effect at least:

in the utility model, the polarity of the middle back contact battery piece is opposite to that of the second main grid line through the first main grid line, and the polarity of the third main grid line is opposite to that of the fourth main grid line; the first main grid line and the second main grid line are positioned in the first area, and the third main grid line and the fourth main grid line are positioned in the second area; along a first direction, a first main grid line and a third main grid line are on the same extension line, and a second main grid line and a fourth main grid line are on the same extension line, wherein the first main grid line and the third main grid line are opposite in polarity, and the second main grid line and the fourth main grid line are opposite in polarity; the number of the first main grid lines and the number of the fourth main grid lines are respectively 7-13; the first main grid line, the second main grid line, the third main grid line and the fourth main grid line are respectively provided with welding spots along a first direction, the number of the welding spots is 3-8, and the scheme adopts the combination of a multi-main grid line (MBB) screen printing plate and a back contact battery, so that on one hand, the short circuit current (Isc) can be improved through a multi-main grid structure, the back contact battery efficiency is improved, meanwhile, the use amount of fine grid lines can be reduced, and cost reduction and efficiency improvement are realized; on the other hand, because the distribution of a plurality of main grid lines in the multi-main-grid structure is more uniform, the stress of the plurality of main grid lines and the welding wire is uniformly distributed during welding, and the risk of fragments of the back contact battery is reduced.

Of course, it is not necessary for any product of the present invention to achieve all of the above-described technical effects simultaneously.

Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments of the invention, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

Fig. 1 is a schematic structural view of a back contact cell in the related art;

fig. 2 is a schematic structural diagram of a back contact battery provided in the present invention;

fig. 3 is a schematic view of another structure of a back contact battery provided by the present invention;

fig. 4 is another schematic structural diagram of a back contact battery cell provided by the present invention;

fig. 5 is a schematic view of a partial structure of a back contact battery plate provided by the present invention;

fig. 6 is another schematic structural diagram of a back contact battery provided by the present invention;

fig. 7 is a schematic structural diagram of a back contact assembly provided by the present invention;

fig. 8 is a schematic structural diagram of a back contact battery string provided by the present invention;

FIG. 9 is an enlarged view at B in FIG. 8;

fig. 10 is an enlarged view at a in fig. 8.

Detailed Description

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: unless specifically stated otherwise, the relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

With the development of photovoltaic technology, back contact batteries get more and more attention due to higher conversion efficiency, the existing mature packaging technology comprises the steps of welding a conductive back plate and a special welding wire after screen optimization, insulating a dissimilar electrode in the preparation process of the back contact battery, then welding, adopting a non-main-grid design scheme for the back contact battery and the like, but all grid lines of the back contact battery cause uneven stress on the back surface to cause warping of a battery piece, and the back contact battery is easy to generate fragments and other adverse phenomena, so that the conductive back plate cannot be compatible with a double-sided assembly, and the cost is high.

Fig. 1 is a schematic structural diagram of a back contact cell 100' in the related art; referring to fig. 1, the back contact cell 100' includes a first region 1', a blank region 3' and a second region 2' arranged along a first direction, wherein the first direction X ' is a direction from the first region 1' to the second region 2 '; the back contact cell 100' further includes first and second main gate lines 10' and 11' arranged in a staggered manner along the second direction Y ' and extending along the first direction X ', and third and fourth main gate lines 20' and 21' arranged in a staggered manner along the second direction Y ' and extending along the first direction X ', the second direction Y ' intersecting the first direction X ', the first and second main gate lines 10' and 11' being located in the first region 1', the third and fourth main gate lines 20' and 21' being located in the second region, wherein the first and second main gate lines 10' and 11' have opposite polarities, the third and fourth main gate lines 20' and 21' have opposite polarities, the first and third main gate lines 10' and 20' are located on the same extension line along the first direction X ', and the first and third main gate lines 10' and 20' have the same polarity; the second main grid line 11' and the fourth main grid line 21' are located on the same extension line along the first direction X ', and the polarity of the second main grid line 11' is the same as that of the fourth main grid line 21', but during welding, the cut half back-contact battery piece needs to be rotated clockwise or counterclockwise by 180 °, so that the main grid lines with opposite polarities can be welded through welding wires.

Fig. 2 is a schematic structural diagram of a back contact battery cell provided in the present invention; referring to fig. 2, the present embodiment provides a back contact cell 100, where each back contact cell 100 includes first regions 1 and second regions 2 arranged in a staggered manner along a first direction X, where the first direction X is a direction from the first region 1 to the second region 2;

the liquid crystal display panel further comprises a first main grid line 10 and a second main grid line 11 which are arranged in a staggered mode along a second direction Y and extend along a first direction X, and a third main grid line 20 and a fourth main grid line 21 which are arranged in a staggered mode along the second direction Y and extend along the first direction X, wherein the first main grid line 10 and the second main grid line 11 are opposite in polarity, the third main grid line 20 and the fourth main grid line 21 are opposite in polarity, and the second direction Y intersects with the first direction X;

the first main gate line 10 and the second main gate line 11 are located in the first region 1, and the third main gate line 20 and the fourth main gate line 21 are located in the second region 2;

in the first direction X, the first main gate line 10 and the third main gate line 20 are on the same extension line, and the second main gate line 11 and the fourth main gate line 21 are on the same extension line, wherein the first main gate line 10 and the third main gate line 20 have opposite polarities, and the second main gate line 11 and the fourth main gate line 21 have opposite polarities;

the number of the first main grid lines 10 and the number of the fourth main grid lines 21 are respectively 7-13;

the first main gate line 10, the second main gate line 11, the third main gate line 20 and the fourth main gate line 21 are respectively provided with welding spots 4 along the first direction X, and the number of the welding spots 4 is 3-8.

Specifically, the back contact cell 100 may be a whole cell or a half cell; each back contact cell 100 comprises a first region 1 and a second region 2, wherein the first region 1 and the second region 2 are arranged in a staggered manner along a first direction X, and the first direction X is a direction from the first region 1 to the second region 2; of course, the half back contact cell 100 may also include first regions 1 and second regions 2 arranged in a staggered manner along the first direction X, and further include a blank region 3 located between the first regions 1 and the second regions 2, where the blank region 3 is used for subsequent slicing;

the first main gate line 10, the second main gate line 11, the third main gate line 20 and the fourth main gate line 21 are respectively arranged along a second direction Y in a staggered manner and extend along a first direction X, wherein the second direction Y intersects with the first direction X, and optionally, the second direction Y is perpendicular to the first direction X;

the first main gate line 10 and the second main gate line 11 are located in the first region 1, the first main gate line 10 and the second main gate line 11 have opposite polarities, and the third main gate line 20 and the fourth main gate line 21 are located in the second region 2; the first main gate line 10 and the second main gate line 11 have opposite polarities, and the third main gate line 20 and the fourth main gate line 21 have opposite polarities;

in the first direction X, the first main gate line 10 and the third main gate line 20 are on the same extension line, and the second main gate line 11 and the fourth main gate line 21 are on the same extension line, that is, the first main gate line 10 and the third main gate line 20 are symmetrical in the first direction X, and the second main gate line 11 and the fourth main gate line 21 are symmetrical in the first direction X, wherein the first main gate line 10 and the third main gate line 20 have opposite polarities, and the second main gate line 11 and the fourth main gate line 21 have opposite polarities, such as the first main gate line 10 is a positive electrode, the second main gate line 11 is a negative electrode, the third main gate line 20 is a negative electrode, and the fourth main gate line 21 is a positive electrode; or, the first main gate line 10 is a negative electrode, the second main gate line 11 is a positive electrode, the third main gate line 20 is a positive electrode, and the fourth main gate line 21 is a negative electrode;

the number of the first main gate lines 10 and the number of the fourth main gate lines 21 are respectively 7 to 13, and the number of the first main gate lines 10 and the number of the fourth main gate lines 21 may be respectively an odd number or an even number;

the first main grid line 10, the second main grid line 11, the third main grid line 20 and the fourth main grid line 21 are respectively provided with welding spots 4 along the first direction X, the number of the welding spots 4 on each half of the first main grid line 10, the second main grid line 11, the third main grid line 20 and the fourth main grid line 21 is not less than 3, and the number of the welding spots 4 can be 3-8, because the first main grid line 10, the second main grid line 11, the third main grid line 20 and the fourth main grid line 21 adopt a fish-free cross line design at the head end and the tail end, the welding spots 4 are arranged near the edge for welding.

It should be noted that: the first main grid line 10, the second main grid line 11, the third main grid line 20 and the fourth main grid line 21 are all located on the back of the back contact cell piece 100, so that shielding of the front main grid to the back contact cell piece 100 is reduced, the cell short-circuit current Isc is improved, and the conversion efficiency of the photovoltaic cell is improved; the first main gate line 10, the second main gate line 11, the third main gate line 20, and the fourth main gate line 21 are symmetrical left and right, and the first main gate line 10, the third main gate line 20, the second main gate line 11, and the fourth main gate line 21 are symmetrical up and down;

according to the above embodiment, the utility model provides a back contact battery piece 100 has realized following beneficial effect at least:

in this embodiment, the first main gate line 10 and the second main gate line 11 have opposite polarities, and the third main gate line 20 and the fourth main gate line 21 have opposite polarities; the first main gate line 10 and the second main gate line 11 are located in the first region 1, and the third main gate line 20 and the fourth main gate line 21 are located in the second region 2; in the first direction X, the first main gate line 10 and the third main gate line 20 are on the same extension line, and the second main gate line 11 and the fourth main gate line 21 are on the same extension line, wherein the first main gate line 10 and the third main gate line 20 have opposite polarities, and the second main gate line 11 and the fourth main gate line 21 have opposite polarities; the number of the first main grid lines 10 and the number of the fourth main grid lines 21 are respectively 7-13; the first main grid line 10, the second main grid line 11, the third main grid line 20 and the fourth main grid line 21 are respectively provided with welding spots 4 along a first direction X, the number of the welding spots 4 is 3-8, and the MBB screen printing plate is combined with the back contact battery in the scheme, so that on one hand, the short-circuit current Isc can be improved through a multi-main-grid structure, the back contact battery efficiency is improved, meanwhile, the use amount of fine grid lines can be reduced, and cost reduction and efficiency improvement are realized; on the other hand, because the distribution of a plurality of main grid lines in the multi-main-grid structure is more uniform, the stress of the plurality of main grid lines and the welding wire is uniformly distributed during welding, and the risk of fragments of the back contact battery is reduced.

Optionally, at least one of the first, second, third and fourth bus bars 10, 11, 20 and 21 has a width in the second direction Y of 30 μm to 60 μm.

Specifically, if the width of at least one of the first, second, third, and fourth main gate lines 10, 11, 20, and 21 in the second direction Y is less than 30 μm, the reliability of the main gate cannot be ensured; if at least one of the first main grid line 10, the second main grid line 11, the third main grid line 20 and the fourth main grid line 21 is greater than 30 μm along the width of the second direction Y, not only the usage amount of silver paste needs to be increased, thereby increasing the cost, but also the shielding on the effective area of the battery is increased, thereby increasing the efficiency of influencing the back surface of the back contact battery, therefore, at least one of the first main grid line 10, the second main grid line 11, the third main grid line 20 and the fourth main grid line 21 is designed to be 30 μm-60 μm along the width of the second direction Y, not only the shielding on the effective area of the battery can be reduced, thereby reducing the efficiency of influencing the back surface of the back contact battery, but also the usage amount of the silver paste is reduced, thereby reducing the cost, and simultaneously increasing the reliability of the main grid.

In an embodiment, fig. 3 is a schematic structural diagram of a back contact battery provided by the present invention; referring to fig. 3, the back contact cell in this embodiment further includes first and second

thin gate lines

12 and 13 alternately arranged in the first direction X and extending in the second direction Y, and third and fourth

thin gate lines

22 and 23 alternately arranged in the first direction X and extending in the second direction Y;

the first thin gate line 12 and the second thin gate line 13 are located in the first region 1, the first thin gate line 12 is connected to the first main gate line 10, and the second thin gate line 13 is connected to the second main gate line 11, wherein the first thin gate line 12 and the first main gate line 10 have the same polarity, and the second thin gate line 13 and the second main gate line 11 have the same polarity;

the third thin gate line 22 and the fourth thin gate line 23 are located in the second region 2, the third thin gate line 22 is connected to the third main gate line 20, and the fourth thin gate line 23 is connected to the fourth main gate line 21, where the third thin gate line 22 and the third main gate line 20 have the same polarity, and the fourth thin gate line 23 and the fourth main gate line 21 have the same polarity.

Specifically, the back contact cell 100 further includes first thin gate lines 12, second thin gate lines 13, third thin gate lines 22, and fourth thin gate lines 23, where the first thin gate lines 12, the second thin gate lines 13, the third thin gate lines 22, and the fourth thin gate lines 23 are respectively arranged in a staggered manner in the first direction X and extend in the second direction Y, where the first thin gate lines 12, the second thin gate lines 13, the third thin gate lines 22, and the fourth thin gate lines 23 are all located on the back of the back contact cell 100, which is equivalent to that the main gate lines and the thin gate lines are all located on the back of the back contact cell 100, so that shielding of the front gate lines on the back contact cell 100 is reduced, a cell short-circuit current Isc is improved, and thus conversion efficiency of the photovoltaic cell is further improved;

the first thin gate line 12 and the second thin gate line 13 are located in the first region 1, the first thin gate line 12 is electrically connected to the first main gate line 10, and the second thin gate line 13 is electrically connected to the second main gate line 11, optionally, the first thin gate line 12 may be vertically connected to the first main gate line 10, and the second thin gate line 13 may be vertically connected to the second main gate line 11, where the first thin gate line 12 has the same polarity as the first main gate line 10, and the second thin gate line 13 has the same polarity as the second main gate line 11, if the first main gate line 10 is an anode, the first thin gate line 12 is also an anode; the second main grid line 11 is a negative electrode, and the first fine grid line 12 is also a negative electrode; of course, the first main gate line 10 is a negative electrode, and the first fine gate line 12 is also a negative electrode; the second main gate line 11 is a positive electrode, and the first thin gate line 12 is also a positive electrode;

the third thin gate line 22 and the fourth thin gate line 23 are located in the second region 2, the third thin gate line 22 is electrically connected to the third main gate line 20, and the fourth thin gate line 23 is electrically connected to the fourth main gate line 21, optionally, the third thin gate line 22 may be vertically connected to the third main gate line 20, and the fourth thin gate line 23 may be vertically connected to the fourth main gate line 21, where the third thin gate line 22 and the third main gate line 20 have the same polarity, and the fourth thin gate line 23 and the fourth main gate line 21 have the same polarity, for example, the third main gate line 20 is a negative electrode, the third thin gate line 22 is a negative electrode, the fourth main gate line 21 is a positive electrode, and the fourth thin gate line 23 is a positive electrode, or the third main gate line 20 is a positive electrode, the third thin gate line 22 is a positive electrode, the fourth main gate line 21 is a negative electrode, and the fourth thin gate line 23 is a negative electrode.

In the above scheme, carriers can be collected through the first thin gate line 12, the second thin gate line 13, the third thin gate line 22 and the fourth thin gate line 23, and the back contact battery efficiency is further improved.

It should be noted that: the distance between the fine grid and the main grid with opposite polarity is larger than 0, and if the distance between the fine grid and the main grid with opposite polarity is smaller than 0.2mm, the short circuit risk exists; if the distance between the fine grid and the main grid with opposite polarity is larger than 0.5mm, the current collection is affected, and the battery efficiency is affected, therefore, the distance between the fine grid and the main grid with opposite polarity is designed to be 0.2-0.5mm, which not only can increase the current collection and improve the battery efficiency, but also can avoid the short circuit risk, such as the distance between the first fine grid line 12 and the second main grid, the distance between the second fine grid line 13 and the first main grid line 10, the distance between the third fine grid line 22 and the fourth main grid line 21, and the distance between the fourth fine grid line 23 and the third main grid line 20 are designed to be 0.2-0.5, and in principle, the smaller the distance between the fine grid and the main grid with opposite polarity is better under the condition of ensuring no short circuit, such as the distance between the fine grid and the main grid with opposite polarity is designed to be 0.25-0.4mm.

Optionally, at least one of the first thin gate line 12, the second thin gate line 13, the third thin gate line 22, and the fourth thin gate line 23 has a width along the first direction X of 20 μm to 40 μm.

Specifically, if the width of at least one of the first thin gate line 12, the second thin gate line 13, the third thin gate line 22, and the fourth thin gate line 23 along the second direction Y is less than 20 μm, the reliability of the thin gate cannot be ensured; if the width of at least one of the first thin grid line 12, the second thin grid line 13, the third thin grid line 22 and the fourth thin grid line 23 along the second direction Y is greater than 40 μm, the usage amount of silver paste needs to be increased, so that the cost is increased, and the shielding on the effective area of the battery is increased, so that the efficiency of influencing the back surface of the back contact battery is increased, therefore, the width of at least one of the first thin grid line 12, the second thin grid line 13, the third thin grid line 22 and the fourth thin grid line 23 along the second direction Y is designed to be 20 μm-40 μm, so that the usage amount of the silver paste can be reduced, the cost is reduced, and the reliability of the thin grid can be increased.

In one embodiment, fig. 4 is a schematic structural diagram of a back contact battery cell provided by the present invention; fig. 5 is a schematic view of a partial structure of a back contact battery plate provided by the present invention; referring to fig. 4 and 5, the bus bars adjacent to the edge of the battery parallel to the first direction X are edge bus bars 14, and at least one welding point 4 on the edge bus bars 14 is a first edge welding point 41;

the main grid line between the two edge main grid lines 14 is a middle main grid line 15, and at least one welding point 4 on the middle main grid line 15 is a first middle welding point 42;

the area of the first edge weld 41 is larger than the area of the first middle weld 42.

Specifically, the main grid line adjacent to the battery edge 5 parallel to the first direction X is an edge main grid line 14, and at least one welding point 4 located on the edge main grid line 14 is a first edge welding point 41; that is, the main grid lines parallel to the first direction X and close to the battery edge 5 are edge main grid lines 14, and a plurality of welding spots 4 are arranged on the edge main grid lines 14 along the first direction X; the main grid line between the two edge main grid lines 14 is a middle main grid line 15, and a plurality of welding points 4 designed on the middle main grid line 15 are first middle welding points 42; the area of the welding point 41 at the first edge is larger than that of the welding point 42 at the first middle part, and the size of the welding point 4 is optimized by enabling the area of the welding point 41 at the first edge to be larger than that of the welding point 42 at the first middle part, so that the convenience of the welding point 4 and a welding wire during welding can be improved, and the effective fixation of the welding point 4 and the welding wire can be ensured; if the area of the welding point 41 at the first edge is 1-2.2mm²As follows, there may be a problem in the pulling force during soldering, which affects the reliability, if the area of the solder 41 at the first edge is 2mm²Therefore, the silver paste consumption is increased, the cost of the back contact battery is improved, and the area of the welding spot 41 at the first edge can be designed to be 1-2.2mm²The tension during welding is improved, the reliability is improved, the silver paste consumption can be reduced, and the cost of the back contact battery is reduced; if the area of the first middle welding point 42 is 0.5mm²As follows, the tension force during welding may be problematic, which affects the reliability, if the area of the first middle welding point 42 is 1.8mm²Above, increase silver thick liquid consumption, promote the battery cost, consequently, can design 0.5-1.8mm with first middle department solder joint 42 area²The tension force during welding is improved, the reliability is improved, the silver paste consumption can be reduced, and the cost of the back contact battery is reduced; the shape of the welding spots 4 may be rectangular or approximately diamond-shaped.

Optionally, with continued reference to fig. 6, the distance between the first edge weld 41 and the cell edge 5 in the second direction Y is 5mm-8mm.

Specifically, if the distance between the first edge welding point 41 and the battery edge 5 along the second direction Y is less than 5mm, the precision of the manufacturing process cannot be achieved, and if the distance between the first edge welding point 41 and the battery edge 5 along the second direction Y is greater than 8mm, the back efficiency of the battery is affected, so that the distance between the first edge welding point 41 and the battery edge 5 along the second direction Y is 5mm-8mm, the back efficiency of the battery can be improved, and the precision of the manufacturing process can be achieved.

In one embodiment, along the first direction X, the solder point 4 at the head and tail end of the same bus bar is a second edge solder point 43, and the solder point 4 between two first edge solder points 41 is a second middle solder point 44;

the area of the weld 43 at the second edge is greater than the area of the weld 44 at the second middle.

Specifically, in the first direction X, the welding spot 4 at the head and tail end of the same main grid line is the second edge welding spot 43, the welding spot 4 between the two second edge welding spots 43 is the second middle welding spot 44, the area of the second edge welding spot 43 is larger than that of the second middle welding spot 44, and the size of the welding spot 4 is optimized by making the area of the second edge welding spot 43 larger than that of the second middle welding spot 44, so that convenience of welding the welding spot 4 and a welding wire during welding can be increased, and the effective fixation of the welding spot 4 and the welding wire can be ensured; if the area of the welding point 43 at the second edge is 1-2mm²As follows, the pulling force during welding may have a problem, which affects the reliability, if the area of the welding point 43 at the second edge is 2mm²Above, increase silver thick liquid consumption, promote back contact battery cost, consequently, can design in 1-2.2mm with second edge solder joint 43 area²The tension force during welding is improved, the reliability is improved, the silver paste consumption can be reduced, and the cost of the back contact battery is reduced; if the second intermediate spot 44 has an area of 0.5mm²As follows, the tension force during welding may have a problem, which affects the reliability, if the welding point 44 at the second middle part has an area of 1.8mm²Above, increase silver thick liquid consumption, promote the battery cost, consequently, can design 0.5-1.8mm with second middle department solder joint 44 area²The tension during welding is improved, the reliability is improved, the silver paste consumption can be reduced, and the cost of the back contact battery is reduced; the shape of the welding spots 4 may be rectangular or approximately diamond-shaped.

Fig. 7 is a schematic structural diagram of a back contact assembly provided by the present invention; fig. 8 is a schematic structural diagram of a back contact battery string provided by the present invention; referring to fig. 7 and 8, the present invention further provides a back contact assembly 200, the back contact assembly 200 includes a glass 201, a first packaging adhesive film 202, a back contact battery string 203, a second packaging adhesive film 204 and a back plate 205, which are sequentially arranged from top to bottom, wherein the back contact battery string 203 is composed of a plurality of back contact battery pieces 100; the glass 201 may be double coated glass, and both the first packaging adhesive film 202 and the second packaging adhesive film 204 may be POE adhesive films or EVA adhesive films;

each back contact cell 100 includes first regions 1 and second regions 2 arranged in a staggered manner along a first direction X, where the first direction X is a direction from the first region 1 to the second region 2;

the first main gate line 10, the second main gate line 11, the third main gate line 20 and the fourth main gate line 21 are respectively provided with welding spots 4 along a first direction X, and the number of the welding spots 4 is 3-8;

in the first direction X, adjacent back contact battery pieces 100 are connected by a welding wire 206, and the diameter of the welding wire 206 is 0.2-0.4mm.

Specifically, the back contact assembly 200 comprises a glass 201, a first packaging adhesive film 202, a back contact cell string 203, a second packaging adhesive film 204 and a back plate 205 which are sequentially arranged from top to bottom, wherein the back contact cell string 203 is composed of a plurality of back contact cell pieces 100; POE is an ethylene-octene copolymer, consists of saturated fatty chains, and has the characteristics of good weather resistance, ultraviolet aging resistance, excellent heat resistance and low temperature resistance, wide use temperature range, good light transmittance, excellent electric insulation property, high cost performance, easiness in processing and the like; the EVA adhesive film is the most common adhesive film, and the main components are ethylene-vinyl acetate copolymer (EVA), a small amount of cross-linking agent, auxiliary cross-linking agent, anti-aging agent and other functional auxiliary agents. The EVA is prepared by copolymerizing two monomers, and the ethylene chain break is relatively stable; the back plate 205 may be a black back plate or a black high-reflective back plate;

the back contact cell is adopted for the back contact cell 100 in the back contact cell string, and details are not repeated herein.

Adjacent back contact battery pieces 100 are connected through a welding wire 206 along a first direction X, for example, the positive first main grid line 10 and the negative third main grid line 20, the negative second main grid line 11 and the positive fourth main grid line 21 are directly connected through the welding wire 206, or the negative first main grid line 10 and the positive third main grid line 20, the positive second main grid line 11 and the negative fourth main grid line 21 are directly connected through the welding wire 206, so that warping of the back contact battery pieces 100 is effectively improved, and the problem of hidden cracking caused by excessive stress is avoided; if the diameter of the welding wire 206 is less than 0.2mm, the device cannot weld the welding wire 206 and the welding point 4; if the diameter of the welding wire 206 is larger than 0.4mm, not only is the stress of the welding wire 206 large, making the back contact battery susceptible to subfissure, but also the cost of the welding wire 206 is increased, and therefore, the diameter of the welding wire 206 is designed to be 0.2-0.4mm. Not only can the risk that the back contact battery has hidden crack be reduced, but also the cost of the welding wire 206 is reduced, and meanwhile, the welding wire 206 is convenient to be connected with the welding spot 4.

According to the above embodiment, the utility model provides a back of body contact subassembly 200 has realized following beneficial effect at least:

by combining the back contact battery piece 100 with the MBB screen printing plate, on the first hand, the positive and negative main grid lines can be directly connected through the welding wire 206, the warping of the back contact battery piece 100 can be effectively improved, and the problem of hidden cracking caused by overlarge stress is avoided; in the second aspect, the short-circuit current (Isc) can be improved through the multi-main-grid structure, so that the back contact battery efficiency is improved, meanwhile, the use amount of the thin grid lines can be reduced, and cost reduction and efficiency improvement are realized; in the third aspect, because the distribution of the main grid lines in the multi-main-grid structure is uniform, the stress of the main grid lines and the welding wires is uniformly distributed during welding, and the risk of fragments of the back contact battery is reduced.

Alternatively, FIG. 9 is an enlarged view at B of FIG. 8; referring to fig. 9, in the second direction Y, the diameter of the solder wire 206 is d1, the widths of the first, second, third, and fourth bus bars 10, 11, 20, and 21 are d2, respectively, and the width of the solder joint 4 is d3, where d3 is greater than or equal to d1 and greater than or equal to d2, and as shown in fig. 4, in the second direction Y, the widths d2 of the first, second, third, and fourth bus bars 10, 11, 20, and 21 are 60 μm, respectively, the width of the solder joint 41 at the first edge may be 2.2mm, the width of the solder joint 42 at the first middle position may be 0.9mm, and the diameter d1 of the solder wire 206 is 0.4mm; or, in the second direction Y, the widths d2 of the first, second, third, and fourth main gate lines 10, 11, 20, and 21 are 50 μm, respectively, and as shown in fig. 6, the width of the solder joint 43d3 at the second edge may be 2.2mm, the width of the solder joint 44d3 at the second middle may be 0.9mm, and the diameter d1 of the solder wire 206 is 0.3mm, with this scheme, even if the solder wire 206 is offset, the solder wire 206 can be effectively ensured to contact with the solder joint 4 and the main gate line, respectively.

It should be noted that: only the width of the first main gate line 10 is shown in fig. 9, and the widths of the second, third, and fourth

main gate lines

11, 20, and 21 can refer to the width of the first main gate line 10 in fig. 9;

in one embodiment, with continued reference to fig. 8, the back contact assembly 200 further includes first and second

thin gate lines

12 and 13 alternately arranged along the first direction X and extending along the second direction Y, and third and fourth

thin gate lines

22 and 23 alternately arranged along the first direction X and extending along the second direction Y;

the third thin gate line 22 and the fourth thin gate line 23 are located in the second region 2, the third thin gate line 22 is connected to the third main gate line 20, and the fourth thin gate line 23 is connected to the fourth main gate line 21, where the third thin gate line 22 and the third main gate line 20 have the same polarity, and the fourth thin gate line 23 and the fourth main gate line 21 have the same polarity;

the back contact type solar cell module further comprises an insulating adhesive film 207, wherein the insulating adhesive film 207 is positioned on one side of the back contact type solar cell 100 close to the second packaging adhesive film 204, that is, the insulating adhesive film 207 is positioned on the back surface of the back contact type solar cell 100, the insulating adhesive film 207 is made of an epoxy system or an organic silicon system, and the two materials are transparent or semitransparent and need to ensure the reliability of the back contact assembly 200;

on the back contact cell 100 perpendicular to the back contact cell, the insulating glue film 207 overlaps with the first thin grid line 12, the second thin grid line 13, the third thin grid line 22 and the fourth thin grid line 23, and does not overlap with the first main grid line 10, the second main grid line 11, the third main grid line 20 and the fourth main grid line 21; that is to say, the first thin gate line 12, the second thin gate line 13, the third thin gate line 22 and the fourth thin gate line 23 are respectively printed with the insulating glue film 207 by the screen printing method on the side close to the second main gate line 11, the first main gate line 10, the fourth main gate line 21 and the third main gate line 20, but the insulating glue film 207 is not in contact with the second main gate line 11, the first main gate line 10, the fourth main gate line 21 and the third main gate line 20, so that not only the reliability of the back contact assembly 200 can be ensured, but also the cost of the back contact assembly 200 can be reduced as a whole.

Optionally, fig. 10 is an enlarged view of a portion a in fig. 8, and referring to fig. 10, a width of the insulating adhesive film 207 along the first direction X is d4, widths of the first fine gate line 12, the second fine gate line 13, the third fine gate line 22 and the fourth fine gate line 23 along the first direction X are d5, a distance between the first fine gate line 12 and the second fine gate line 13 along the first direction X, and distances between the third fine gate line 22 and the fourth fine gate line 23 along the first direction X are d6, respectively, where d6 > d4 > d5, that is, a distance d6 between two opposite-polarity fine gates is greater than a width d4 of the insulating adhesive film 207, and a width d4 of the insulating adhesive film 207 is greater than a width d5 of each of the fine gate line, so that the opposite-polarity electrodes near the main gates are treated by a non-transparent or transparent insulating adhesive, which effectively avoids a short circuit risk caused by a solder wire during back contact battery welding.

It should be noted that: on the basis of ensuring the performance of the back contact assembly 200, the smaller the area of the insulating adhesive film 207, the better; in fig. 10, taking the width of the second thin gate line 13 and the distance between the first thin gate line 12 and the second thin gate line 13 along the first direction X as an example, the widths of the second thin gate line 13, the third thin gate line 22 and the fourth thin gate line 23 and the distance between the third thin gate line 22 and the fourth thin gate line 23 along the first direction X can refer to fig. 10;

optionally, as shown in fig. 8, the grammage of the first packaging adhesive film 202 and the second packaging adhesive film 204 is 250-350g/m²(ii) a And/or

On the back contact battery piece 100, the thickness of the first packaging adhesive film 202 is 0.25mm-0.4mm, and the thickness of the second packaging adhesive film 204 is 0.35mm-0.7mm;

specifically, since the front side of the back contact cell 100 has no welding wire 206, the lower the gram weight of the first packaging adhesive film 202 is, the better, but considering the manufacturability of the packaging adhesive film and the matching of the glass 201 and the back contact cell 100, the gram weight of the first packaging adhesive film 202 needs to be more than 200g/m²Optionally, the gram weight of the first packaging adhesive film 202 is 250-350g/m²The manufacturability of the packaging adhesive film can be achieved, and the cost of the back contact assembly 200 is reduced; the back of the back contact cell 100 is designed with a welding wire 206, or 250-350g/m²Not only has manufacturability, but also reduces the cost of the back contact assembly 200;

in principle, the smaller the thickness of the first packaging adhesive film 202 is, the lower the cost thereof is, and on the back contact battery piece 100 perpendicular to the back contact battery piece, since the front surface of the back contact battery piece 100 has no welding wire 206, but considering the reliability of the packaging adhesive film, the thickness of the first packaging adhesive film 202 can be designed to be 0.25-0.4mm, which not only can improve the reliability of the packaging adhesive film, but also can reduce the reliability of the back contact assembly 200; however, since the back surface of the back contact cell 100 has the welding wire 206, the thickness of the second packaging adhesive film 204 is 0.35mm-0.7mm on the back contact cell 100, which not only can improve the reliability, but also can reduce the cost of the back contact cell 100.

According to the above embodiment, the utility model provides a back of body contact battery piece and back of body contact subassembly has realized following beneficial effect at least:

in the utility model, the polarity of the middle back contact battery piece is opposite to that of the second main grid line through the first main grid line, and the polarity of the third main grid line is opposite to that of the fourth main grid line; the first main grid line and the second main grid line are positioned in the first area, and the third main grid line and the fourth main grid line are positioned in the second area; along a first direction, a first main grid line and a third main grid line are on the same extension line, and a second main grid line and a fourth main grid line are on the same extension line, wherein the first main grid line and the third main grid line are opposite in polarity, and the second main grid line and the fourth main grid line are opposite in polarity; the number of the first main grid lines and the number of the fourth main grid lines are respectively 7-13; the first main grid line, the second main grid line, the third main grid line and the fourth main grid line are respectively provided with welding spots along a first direction, the number of the welding spots is 3-8, the MBB screen printing plate is combined with a back contact battery, on one hand, the short-circuit current Isc can be improved through a multi-main-grid structure, so that the back contact battery efficiency is improved, meanwhile, the use amount of thin grid lines can be reduced, and cost reduction and efficiency improvement are realized; on the other hand, because the distribution of the main grid lines in the multi-main-grid structure is uniform, the stress of the main grid lines and a welding wire is uniformly distributed during welding, and the risk of fragments of the back contact battery is reduced; the back contact assembly can enable the positive and negative main grid lines to be directly connected through the welding wires, so that warping of a back contact battery piece can be effectively improved, and the problem of hidden cracking caused by overlarge stress is avoided;

although certain specific embodiments of the present invention have been described in detail by way of example, it should be understood by those skilled in the art that the foregoing examples are for purposes of illustration only and are not intended to limit the scope of the invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. The back contact cell is characterized in that each back contact cell comprises a first area and a second area which are arranged in a staggered mode along a first direction, and the first direction is a direction from the first area to the second area;

2. The back contact cell of claim 1, wherein at least one of the first, second, third, and fourth bus bars has a width in the second direction of 30 μ ι η to 60 μ ι η.

3. The back contact cell of claim 1, further comprising first and second thin gate lines arranged in a staggered manner along the first direction and extending along the second direction, and third and fourth thin gate lines arranged in a staggered manner along the first direction and extending along the second direction;

4. The back contact cell of claim 3, wherein at least one of the first, second, third and fourth fine grid lines has a width in the first direction of 20 μm to 40 μm.

5. The back contact cell of claim 1,

the main grid lines adjacent to the battery edge parallel to the first direction are edge main grid lines, and at least one welding spot on the edge main grid lines is a first edge welding spot;

the area of the welding point at the first edge is larger than that of the welding point at the first middle part.

6. The back contact cell piece of claim 5, wherein the distance between the first edge weld and the cell edge in the second direction is 5mm to 8mm.

7. The back contact cell of claim 1,

along the first direction, the welding point at the tail end of the upper head of the same main grid line is a second edge welding point, and the welding point between the two first edge welding points is a second middle welding point;

8. A back contact assembly is characterized by comprising glass, a first packaging adhesive film, a back contact battery string, a second packaging adhesive film and a back plate which are sequentially arranged from top to bottom, wherein the back contact battery string consists of a plurality of back contact battery pieces;

and in the first direction, the adjacent back contact battery plates are connected through welding wires, and the diameter of each welding wire is 0.2-0.4mm.

9. The back contact assembly of claim 8, wherein the diameter of the solder wire is d1, the widths of the first, second, third and fourth bus bars are d2, respectively, and the width of the solder joint is d3, along the second direction, wherein d3 is greater than or equal to d1 and greater than or equal to d2.

10. The back contact assembly of claim 8,

the first thin grid line and the second thin grid line are arranged in a staggered mode along the first direction and extend along the second direction, and the third thin grid line and the fourth thin grid line are arranged in a staggered mode along the first direction and extend along the second direction;

the back contact battery piece is positioned on one side, close to the second packaging adhesive film, of the back contact battery piece;

11. The back contact assembly of claim 10, wherein the width of the insulating adhesive film along the first direction is d4, the widths of the first, second, third and fourth thin gate lines along the first direction are d5, respectively, a distance between the first and second thin gate lines along the first direction and a distance between the third and fourth thin gate lines along the first direction are d6, respectively, wherein d6 > d4 > d5.

12. The back contact assembly of any one of claims 8-10, wherein the grammage of the first and second packaging adhesive films is 250-350g/m, respectively²(ii) a And/or

On the back contact battery piece, the thickness of the first packaging adhesive film is 0.25mm-0.4mm, and the thickness of the second packaging adhesive film is 0.35mm-0.7mm.