WO2017128668A1

WO2017128668A1 - Front electrode of crystalline silicon solar cell

Info

Publication number: WO2017128668A1
Application number: PCT/CN2016/092194
Authority: WO
Inventors: 何凤琴; 郑璐
Original assignee: 王能青
Priority date: 2016-01-28
Filing date: 2016-07-29
Publication date: 2017-08-03
Also published as: CN105529373A; CN105529373B

Abstract

A front electrode of a crystalline silicon solar cell, comprising multiple secondary grid lines (10) extending in a first direction and arranged in rows at regular intervals, said front electrode also comprising a number M of fine grid lines (20) extending in a second direction and arranged in rows at regular intervals, the fine grid lines (20) and secondary grid lines (10) being electrically connected, the width of the fine grid lines (20) being 0.10-0.25mm, and the number M = 10-20; a number N of welding contacts (30) are provided at intervals on each fine grid line (20), the welding contacts (30) being layered over the fine grid line (20) and electrically connected to said fine grid line (20), the shapes of the welding contacts (30) being two or more of square, circular and elliptical, the length of a side of a square, diameter of a circle or short axis of an ellipse being 0.2-1mm, and the length of a side of a square, diameter of a circle or short axis of an ellipse being greater than the width of a fine grid line (20); the number N = 5-15. The present positive electrode structure can achieve the dual goals of reducing light-blocking area and ensuring smooth delivery of current.

Description

Front electrode of a crystalline silicon solar cell

Technical field

The invention relates to the technical field of solar cells, and in particular to a front electrode of a crystalline silicon solar cell.

Background technique

A crystalline silicon solar cell is an electronic component that converts solar energy into electrical energy. The preparation of crystalline silicon solar cells is generally carried out by processes such as texturing, diffusion, coating, screen printing, and sintering. The velvet is divided into single crystal and polycrystalline velvet. The single crystal battery is formed by the method of alkali velvet to form a pyramid suede on the surface of the silicon wafer, and the polycrystalline battery is formed by using an acid etching method to form a pitted surface on the surface of the silicon wafer. The suede surface of the silicon surface can increase the absorption of sunlight on the surface of the battery to achieve the light trapping effect; the diffusion process forms a PN junction into the interior of the silicon wafer by means of thermal diffusion, so that when light is irradiated, a voltage can be formed inside the silicon wafer. It is the basis of solar cell power generation; the coating process is to reduce the composite of minority carriers on the surface of the battery, and can improve the conversion efficiency of the crystalline silicon solar cell; the screen printing process is to make the electrode of the solar cell, so that when the light is irradiated It is possible to derive the current. Screen printing is one of the most widely used processes in the preparation of crystalline silicon cells. The process sequence is to first print and dry the back electrode, then print and dry the aluminum back field, and finally print and dry the front electrode. When sintering is performed, the silver paste used for preparing the electrode is brought into contact with the battery.

In the front electrode of the crystalline silicon solar cell, the electrode structure generally includes a main gate line and a sub-gate line which are criss-crossed, and the main gate line is electrically connected to the sub-gate line. When there is light, the battery generates a current, and the current flows through the internal emitter to the surface electrode sub-gate line, collects through the sub-gate line and then flows to the battery main grid for export. The current will be lost during the collection of the secondary gate line, which we call the power loss of the resistor. The main grid line and the sub-gate line of the battery are on the light-receiving surface of the battery, which inevitably blocks a part of the light from being irradiated on the surface of the battery, thereby reducing the effective light-receiving area of the battery, which is called optical loss. Regardless of whether it is a P-type or an N-type battery, as long as the electrode structure exists on the front side of the battery, it is necessary to consider the continuous optimization of the electrode structure to achieve the purpose of reducing the shading area and ensuring smooth current export.

In the conventional front electrode structure, the number of main gate lines is usually three, and the width thereof is about 1.5 mm; the number of the sub-gate lines is usually 80 to 100, and the width thereof is about 40 μm. The width of the main gate line is wide, so that The strip of the front electrode and the battery can be soldered well, but the shading area is also large. In recent years, in order to reduce the light-shielding area of the front electrode, a front electrode structure without a main gate is proposed in the industry, mainly to remove three main gate lines in the front electrode structure, leaving only the sub-gate line, after the battery is completed, A very thin cylindrical ribbon is used to directly solder to the secondary grid, and the current is directly extracted by the ribbon. In the welding process of the extremely thin soldering strip and the sub-gate line, the power of the photovoltaic module is lowered due to the abnormality of the soldering or the inability to solder due to the small width of the sub-gate line and the sub-gate line being too low.

Summary of the invention

In view of the deficiencies of the prior art, the present invention provides a front electrode of a crystalline silicon solar cell, which can achieve the purpose of reducing the shading area and ensuring smooth current export.

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

A front electrode of a crystalline silicon solar cell, comprising a plurality of sub-gate lines arranged at a distance from each other in a first direction, wherein the front electrode further comprises M thin gate lines arranged in a spaced relationship from each other in a second direction, the thin The gate line is electrically connected to the sub-gate line, and the width of the fine gate line is 0.10-0.25 mm; wherein M=10-20; wherein each fine grid line is provided with N solders spaced apart from each other a contact point, the solder contact stack is disposed on the fine gate line and electrically connected to the fine gate line, and the shape of the solder contact is set to be two or more of a square shape, a circular shape, and an elliptical shape The length of the square side, the diameter of the circle, or the short side of the ellipse is 0.2 to 1 mm, respectively, and the length of the side of the square, the diameter of the circle, or the length of the short side of the ellipse are respectively greater than The width of the fine grid line is described; wherein N=5-15.

Further, the soldering contact is formed on the fine grid line by a secondary printing process.

Further, the plurality of sub-gate lines are equally spaced along the first direction, the M fine gate lines are equally spaced along the second direction, and the second direction is perpendicular to the first direction.

Further, the number of the sub-gate lines is 80 to 100.

Further, the soldering contact is disposed at a position where the fine gate line intersects the sub-gate line.

Further, N solder contacts on each of the fine gate lines are arranged at equal intervals along the length direction of the thin gate lines.

Further, all of the solder contacts in the front electrode are distributed in an array of N rows x M columns.

Further, different shaped soldering contacts are alternately spaced on each of the fine grid lines.

Further, the width of the fine grid line is 0.2 mm; the shape of the soldering contact includes a square And a circle having a side length of 0.8 mm and a diameter of the circle of 0.8 mm; wherein M = 15, and N = 10.

Further, the shape of the solder contacts on one of the fine grid lines is the same, and the shapes of the solder contacts on the adjacent two fine grid lines are different from each other.

Compared with the prior art, in the front electrode of the crystalline silicon solar cell provided by the embodiment of the present invention, a fine gate line with a larger number of smaller widths is used instead of the main gate line in the prior art, and the overall shading area is smaller. The optical loss is reduced, and a larger number of fine grid lines are evenly distributed on the front surface of the solar cell, so that the current collected by the sub-gate lines can be more smoothly derived, reducing power loss; Large square, round or elliptical welded contacts increase the contact area of the solder joints and the height of the solder joints. When welding the solder ribbons, there is less problem of abnormal soldering of the solder ribbons and the battery sheets.

DRAWINGS

1 is a schematic structural view of a front electrode of a solar cell according to an embodiment of the present invention;

Figure 2 is an enlarged schematic view of a portion A of Figure 1;

3 is an exemplary illustration of an elliptical weld contact in an embodiment of the present invention.

detailed description

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Examples of these embodiments are exemplified in the drawings. The embodiments of the invention shown in the drawings and described in the drawings are merely exemplary, and the invention is not limited to the embodiments.

In this context, it is also to be noted that in order to avoid obscuring the invention by unnecessary detail, only the structures and/or processing steps closely related to the solution according to the invention are shown in the drawings, and the Other details that are not relevant to the present invention.

Referring to FIG. 1 and FIG. 2, the present embodiment provides a front electrode of a crystalline silicon solar cell. As shown in FIG. 1, the front electrode includes two rows spaced apart from each other in the first direction (such as the Y direction in FIG. 1). a plurality of sub-gate lines 10, a plurality of thin gate lines 20 spaced apart from each other in the second direction (in the X direction in FIG. 1), the plurality of sub-gate lines 10 and the plurality of fine gate lines 20 are electrically connected to each other. The sub-gate line 10 is mainly used to collect the photo-generated current generated by the solar cell, and the fine-gate line 20 is used to collect and output the current collected by the sub-gate line 10. Further, each of the fine gate lines 20 is further provided with a plurality of soldering contacts 30 spaced apart from each other, and the soldering contacts 30 are stacked on the fine grid lines 20 and the fine grid lines 20 is electrically connected, and the shape of the soldering contact 30 includes a circle and a square. The soldering contact 30 is mainly used for soldering connection to the solder ribbon after the battery is fabricated. Specifically in this embodiment, on each of the fine grid lines 20, the circular and square solder contacts 30 are alternately spaced apart. Of course, in other embodiments, the differently shaped solder contacts 30 may also be arranged in any order.

The number of the sub-gate lines 10 may be selected from the range of 80 to 100, and the width may be selected to be in the range of 30 to 50 μm. The number M of the fine gate lines 20 can be selected in the range of 10 to 20, and the width D thereof can be selected in the range of 0.10 to 0.25 mm. The number N of the soldering contacts 30 provided on each of the fine gate lines 20 may be selected to be in the range of 5 to 15, and the diameter R of the circular soldering contacts 30 may be selected in the range of 0.2 to 1 mm, and the soldering is required. The diameter R of the contact point 30 is larger than the width of the thin grid line 20, and the side length L of the square solder contact 30 can be selected to be in the range of 0.2 to 1 mm, and the side length of the solder contact 30 is larger than that of the fine gate line 20. width. In the present embodiment, the number of the sub-gate lines 10 is 90, the width of the sub-gate lines 10 is 40 μm; the number of the fine gate lines 20 is M=15, and the width D of the fine gate lines 20 is 0.2 mm; each fine gate The number of solder contacts 30 on line 20 is N = 10, the diameter R of the round solder contacts 30 is 0.8 mm, and the square solder contacts 30 are specifically square with a side length L of 0.8 mm.

The solder contacts 30 are stacked on the fine gate lines 20. Specifically, in the preparation of the front electrode structure, the sub-gate lines 10 and the fine gate lines 20 are first prepared by a single printing process, and then the solder contacts 30 are prepared on the fine gate lines 20 by a secondary printing process.

In this embodiment, as shown in FIG. 1, the plurality of sub-gate lines 10 are arranged at equal intervals in a first direction (such as the Y direction in FIG. 1), and the M thin gate lines 20 are in a second direction ( The X direction in FIG. 1 is equally spaced, and the second direction is perpendicular to the first direction. Further, the soldering contact 30 is disposed at a position where the fine gate line 20 intersects the sub-gate line 10, and N soldering contacts 30 on each of the fine gate lines 20 along the thin grid line 20 is arranged at equal intervals in the longitudinal direction.

More specifically, in the present embodiment, as shown in FIG. 1, the arrangement pitch of the N solder contacts 30 on each of the fine gate lines 20 is equal, and therefore, in the entire front electrode structure, all the solder contacts 30 are provided. An array of N rows x M columns. Specifically, since the circular and square solder contacts 30 are alternately spaced on each of the fine gate lines 20, in the N rows x M columns of the solder contacts 30, the odd number of circular solder contacts 30, even behavior Square solder contacts 30; of course, it is also possible to provide a solder contact 30 with an even number of circular shapes and a solder contact 30 with an odd number of squares.

Further, in other embodiments, the shape of the solder contacts 30 disposed on one of the fine gate lines 20 may be the same, and the shapes of the solder contacts 30 on the adjacent two fine gate lines 20 are mutually Not the same. Specifically, the shape of the soldering contact 30 on the first thin gate line 20 may be set to a circular shape. The shape of the soldering contact 30 on the second fine grid line 20 is square, that is, in the soldering contact 30 of the N rows x M columns, the odd number is a circular soldering contact 30, and the even columns are square solder contacts. Point 30; of course, it can also be set to a solder joint 30 having an even number of circular shapes, and an odd number of square solder contacts 30.

The front electrode of the crystalline silicon solar cell provided by the above embodiments can effectively reduce the light shielding area. Taking the square of the front surface of the solar cell of 156 mm×156 mm as an example, the shading area is calculated according to the front electrode of the existing three main grid and the front electrode structure provided by the embodiment of the present invention:

1. The front electrode structure of the existing three main grids. In the conventional structure of three 1.5mm wide main gate lines and 90 40μm sub grid lines, the main gate lines can be designed in a hollow form to reduce the silver paste used for printing, but all areas of the main grid will still be soldered to a width of about 1.5 mm during soldering. The welding strip blocks the sunlight. Therefore, the shielding area of the sun at the main grid is 1.5 mm × 3 × 156 mm = 702 mm ² ; the shielding area of the sub grid and the four frames is 0.04 mm × (90 + 2) × (153.5 mm - 1.5 mm × 3) + 2 ×153.5 mm × 0.04 mm = 560.6 mm ² . The total occlusion area of the conventional three-main gate front electrode is 1262.6 mm ² .

2. The front electrode structure provided by the embodiment of the invention. According to a specific example, the number of sub-gate lines is 90 and the width is 40 μm; the number of fine gate lines is 15 and the width is 0.2 mm; the number of solder contacts on each fine grid line is 10 The shape of the welded contact is half round, and its diameter R is 0.8 mm, and the other half is square, and its side length is 0.8 mm. then:

a, 15 fine grid lines to the sun blocking area: 0.2mm × 15 × 156mm = 468mm ² ;

b. The obstruction of the sun by the sub-gate line and the four frames is: 0.04 mm × (90 + 2) × (153.5 mm - 0.2 mm × 10) + 0.04 mm × 2 × 153.5 mm = 566.12 mm ² ;

c. The circular pattern of 0.8mm diameter except the fine grid line blocks the sunlight:

[π × 0.4 ² mm ² - (0.8 mm - 0.2 mm) × 0.04 mm - π × 0.4 ² mm ² × 29 ° × 2 ÷ 360 ° - 0.2 × 0.4 × sin14.5] × 75 = 28.32 mm ² ;

d. The occlusion of the square pattern of 0.8 mm side length except the fine grid line is: (0.8 mm-0.2 mm) × 0.8 mm × 75 = 36 mm ² ;

The total area of the above ^{^{occlusion: 468mm 2 + 566.12mm 2 + 28.32mm}} 2 + 36mm 2 = 1098.44mm 2. The front electrode provided by the embodiment of the invention has a reduced light-shielding area of 1262.6 mm ² -1098.44 mm ² =164.16 mm ² compared to the front electrode of the existing three-main gate.

In still other embodiments, reference is made to the front side electrode as provided above, wherein the solder contact 30 can also be designed to be elliptical. That is, the shape of the welding contact 30 includes an ellipse and a circle, or includes an ellipse and a square, and may also include an ellipse and a circle as well as a square, an ellipse and a circle, and a square at each of the fine grid lines 20. The upper alternate interval settings are set in any order. Specifically, an elliptical solder contact 30, as shown in FIG. 3, is also disposed at a position where the thin gate line 20 intersects the sub-gate line 10. The long side of the elliptical shape is the same as the direction in which the thin grid line 20 extends, and the short side of the elliptical shape is the same as the direction in which the sub-gate line 10 extends. The length of the short side of the elliptical shape may be selected to be in the range of 0.2 to 1 mm, and the length L1 of the short side of the solder contact 30 is required to be larger than the width D of the thin gate line 20.

In summary, in the front electrode of the crystalline silicon solar cell provided by the above embodiment, a larger number of fine gate lines with smaller widths are used instead of the main gate lines in the prior art, and the overall shading area is smaller and reduced. Light loss, and a larger number of fine grid lines are evenly distributed on the front side of the solar cell, so that the current collected by the sub-gate line can be more smoothly derived, reducing power loss; in addition, the laminated area on the fine grid line is larger. The square or round or elliptical welding contacts increase the contact area of the solder joints and the height of the solder joints. When soldering the solder ribbon, there is less problem of abnormal soldering of the solder ribbon and the battery.

It should be noted that, in this context, relational terms such as first and second are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply such entities or operations. There is any such actual relationship or order between them. Furthermore, the term "comprises" or "comprises" or "comprises" or any other variations thereof is intended to encompass a non-exclusive inclusion, such that a process, method, article, or device that comprises a plurality of elements includes not only those elements but also Other elements, or elements that are inherent to such a process, method, item, or device. An element that is defined by the phrase "comprising a ..." does not exclude the presence of additional equivalent elements in the process, method, item, or device that comprises the element.

The above description is only a specific embodiment of the present application, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present application. It should be considered as the scope of protection of this application.

Claims

A front electrode of a crystalline silicon solar cell, comprising a plurality of sub-gate lines arranged at a distance from each other in a first direction, wherein

The front surface electrode further includes M thin gate lines which are arranged at intervals in the second direction, and the fine gate lines are electrically connected to the sub-gate lines, and the width of the fine gate lines is 0.10-0.25 mm; M=10～20;

Wherein, each of the fine gate lines is further provided with N soldering contacts spaced apart from each other, and the soldering contact stack is disposed on the fine gate line and electrically connected to the fine gate lines, the soldering contacts The shape of the dots is set to two or more of a square shape, a circular shape, and an elliptical shape, and the length of the side length of the square, the diameter of the circle, or the short side of the ellipse is 0.2 to 1 mm, respectively, and the sides of the square The length of the long, circular diameter or elliptical short side is greater than the width of the fine grid line, respectively; wherein N = 5-15.
The front electrode of a crystalline silicon solar cell according to claim 1, wherein the solder contact is formed on the fine gate line by a secondary printing process.
The front surface electrode of the crystalline silicon solar cell according to claim 1, wherein the plurality of sub-gate lines are arranged at equal intervals in a first direction, and the M fine gate lines are arranged at equal intervals in a second direction, the The two directions are perpendicular to the first direction.
The front surface electrode of a crystalline silicon solar cell according to claim 3, wherein the number of the sub-gate lines is 80 to 100.
The front surface electrode of a crystalline silicon solar cell according to claim 1, wherein the soldering contact is disposed at a position where the fine gate line intersects the sub-gate line.
The front electrode of a crystalline silicon solar cell according to claim 5, wherein the N solder contacts on each of the fine gate lines are arranged at equal intervals along the length direction of the thin gate lines.
The front electrode of a crystalline silicon solar cell according to claim 6, wherein all of the solder contacts in the front electrode are distributed in an array of N rows x M columns.
The front electrode of a crystalline silicon solar cell according to claim 6, wherein each of the fine grid lines has differently shaped solder contacts alternately spaced apart.
A front surface electrode of a crystalline silicon solar cell according to claim 8, wherein said fine gate line has a width of 0.2 mm; said solder contact has a shape including a square and a circle, and said square has a side length of 0.8 mm The diameter of the circle is 0.8 mm; wherein, M = 15, and N = 10.
The front surface electrode of a crystalline silicon solar cell according to claim 6, wherein the shape of the soldering contacts on one of the fine grid lines is the same, and the shapes of the soldering contacts on the adjacent two fine grid lines are different from each other. .
The front surface electrode of a crystalline silicon solar cell according to claim 2, wherein the soldering contact is disposed at a position where the fine gate line intersects the sub-gate line.
A front surface electrode of a crystalline silicon solar cell according to claim 11, wherein N solder contacts on each of the fine gate lines are arranged at equal intervals along the length direction of the thin gate lines.
The front electrode of a crystalline silicon solar cell according to claim 12, wherein all of the solder contacts in the front electrode are distributed in an array of N rows x M columns.
The front electrode of a crystalline silicon solar cell according to claim 12, wherein each of the fine grid lines has differently shaped solder contacts alternately spaced apart.
The front surface electrode of a crystalline silicon solar cell according to claim 12, wherein the shape of the solder contacts on one of the fine grid lines is the same, and the shapes of the solder contacts on the adjacent two fine grid lines are different from each other. .
The front electrode of a crystalline silicon solar cell according to claim 3, wherein the soldering contact is disposed at a position where the fine gate line intersects the sub-gate line.
A front surface electrode of a crystalline silicon solar cell according to claim 16, wherein N solder contacts on each of the fine gate lines are arranged at equal intervals along the length direction of the thin gate lines.
The front electrode of a crystalline silicon solar cell according to claim 17, wherein all of the solder contacts in the front electrode are distributed in an array of N rows x M columns.
The front electrode of a crystalline silicon solar cell according to claim 17, wherein the solder contacts of different shapes are alternately spaced apart on each of the fine grid lines.
A front surface electrode of a crystalline silicon solar cell according to claim 17, wherein the shape of the solder contacts on one of the fine gate lines is the same, and the shapes of the solder contacts on the adjacent two fine grid lines are different from each other. .