阅读说明：本技术 一种用铜丝做主栅的晶硅电池及其组件的制备方法 (Crystalline silicon battery using copper wire as main grid and preparation method of assembly of crystalline silicon battery ) 是由 上官泉元 贾云涛 于 2020-06-10 设计创作，主要内容包括：本发明公开了一种用铜丝做主栅的晶硅电池及其组件的制备方法。其中,晶硅电池是通过透明热熔胶把主栅预先固定在电池硅片上,然后在一定压力和加热下使铜丝与细栅银线焊接,而且正反面所有铜丝各自一端延伸出硅片并分别焊接到一片汇流条上。在形成组件时,正面的汇流条和相邻电池背面的汇流条焊接形成电池串,同时相邻电池串之间也可以通过汇流条沿伸出来的部分相互焊接。由于铜丝被热熔胶固定,解决了铜丝与细栅银线焊接容易脱落的问题,且不需要预先把铜丝贴合在聚合物的覆膜模版上而降低了材料成本,简化了工艺。本发明通过使用焊接铜丝做成主栅,不仅降低了制作电池的银浆耗量,而且增加了光伏组件输出功率；同时通过电池串的连接,可以防止和解决热斑问题。(The invention discloses a crystalline silicon battery using a copper wire as a main grid and a preparation method of a component of the crystalline silicon battery. The crystalline silicon battery is characterized in that a main grid is fixed on a battery silicon chip in advance through transparent hot melt adhesive, then copper wires are welded with thin grid silver wires under certain pressure and heating, and one end of each of all the copper wires on the front side and the back side extends out of the silicon chip and is welded to a bus bar. When the assembly is formed, the bus bars on the front surface and the bus bars on the back surface of the adjacent batteries are welded to form battery strings, and meanwhile, the adjacent battery strings can be mutually welded through the parts extending out of the bus bars. Because the copper wire is fixed by the hot melt adhesive, the problem that the copper wire and the thin grid silver wire are easy to fall off during welding is solved, the copper wire does not need to be attached to the polymer film-coated template in advance, the material cost is reduced, and the process is simplified. According to the invention, the welding copper wires are used for manufacturing the main grid, so that the silver paste consumption for manufacturing the battery is reduced, and the output power of the photovoltaic module is increased; meanwhile, the hot spot problem can be prevented and solved through the connection of the battery strings.)

1. A preparation method of a crystalline silicon battery using a copper wire as a main grid is characterized by comprising the following steps:

1) manufacturing fine grids on the front side and the back side of the battery piece through screen printing of silver paste;

2) directly and vertically placing a plurality of tinned alloy copper wires on the thin grids on the front side and the back side as main grids;

3) adhering the tinned alloy copper wire to the battery piece by using transparent hot melt adhesive to fix the copper wire; one end of a copper wire does not exceed the edge of the battery piece and is in contact with a thin grid on the outermost edge on the front surface of the battery piece, the other end of the copper wire exceeds the edge of the battery piece and is welded on a tinned alloy copper piece serving as a bus bar, one end of the bus bar in the length direction on the front surface corresponds to the edge of the battery piece, and the other end of the bus bar exceeds the edge of the battery piece; on the back surface of the battery piece, two ends of a copper wire do not exceed the edges of the battery piece and are in contact with a thin grid on the outermost edge, one end of the copper wire is welded to a tinned alloy copper piece serving as a bus bar, the length direction of the bus bar on the back surface is perpendicular to the copper wire, one end of all the copper wires on the back surface is in welded connection with the bus bar, and the bus bar on the back surface and the bus bar on the front surface are respectively located at two corresponding ends of the battery piece;

4) and heating, pressurizing and fixing the bus bar, the copper wire and the hot melt adhesive on the back surface of the battery piece and the copper wire and the hot melt adhesive on the front surface of the battery piece to form a battery unit.

2. The method for preparing the crystalline silicon battery with the copper wire as the main grid according to claim 1, wherein the steps 3) and 4) specifically comprise the following steps:

a) straightening all the tinned alloy copper wires and placing the tinned alloy copper wires along the direction vertical to the front and back fine grids;

b) placing two transparent hot melt adhesives along the direction perpendicular to the copper wire, respectively approaching the two edges of the battery piece, and placing a bus bar on the back;

c) pressing the hot melt adhesive, the copper wire, the bus bar on the back and the battery piece by using pressure;

d) heating the battery piece, the copper wire, the bus bar on the back and the hot melt adhesive together to a state that the hot melt adhesive is softened;

e) under the temperature and pressure, the battery piece, the copper wire and the bus bar on the back are bonded together by the hot melt adhesive;

f) cooling, simultaneously removing pressure, solidifying the hot melt adhesive, and fixing the copper wires and the bus bars on the back surface on the battery piece;

g) and welding a bus bar on the front surface of all the extending ends of the copper wires.

3. The method for preparing a crystalline silicon battery with a copper wire as a main grid according to claim 1, wherein in the step 3), the length of the other end of the copper wire on the front surface of the battery piece, which exceeds the edge of the battery piece, is 0.2-10 mm, the excess part of the copper wire is welded on a bus bar on the front surface, and the length of the other end of the bus bar on the front surface, which exceeds the edge of the battery piece, is 1-10 mm.

4. The method for preparing the crystalline silicon battery with the copper wire as the main grid according to claim 1, wherein in the step 3), the bus bar on the back is in welding connection with the copper wire and is fixed on the battery piece by the hot melt adhesive, and the side edge of the bus bar does not exceed the edge of the battery piece; the distance from the outer side edge of the bus bar to the edge of the battery piece is 0-5 mm, the width of the bus bar is 1-10mm, and the thickness of the bus bar is 0.05-0.2 mm.

5. The method for preparing the crystalline silicon battery with the copper wire as the main grid according to claim 4, wherein in the step 4), the bus bar, the copper wire and the hot melt adhesive on the back surface of the battery piece and the copper wire and the hot melt adhesive on the front surface of the battery piece are heated, pressurized and fixed simultaneously; or the bus bar, the copper wire and the hot melt adhesive on the back surface of the battery piece and the copper wire and the hot melt adhesive on the front surface of the battery piece are respectively heated and pressurized for fixing.

6. A preparation method of a crystalline silicon battery component with a copper wire as a main grid is characterized by being manufactured by adopting the crystalline silicon battery with the copper wire as the main grid in any one of claims 1 to 5, and comprising the following steps:

1) firstly, bending the excessive part of the front copper wire of one of two adjacent battery units downwards and welding the excessive part of the front copper wire with the back copper wire of the other battery unit in series, and forming a group of battery units after the plurality of battery units are welded in series;

2) the parts of the battery string units which are welded in series and the other battery string units which are arranged in parallel with the battery string units are mutually lap-welded and connected through the parts of the bus bars on the front side, which extend out of the battery pieces;

3) two ends of the battery string are respectively connected to the main bus bars of the anode and the cathode of the assembly;

4) and adhering the front and back surfaces of the multiple groups of serially welded battery units to a layer of high-transparent glass or other back plate through a whole piece of hot melt adhesive with the area equivalent to that of the assembly to form the crystalline silicon battery assembly.

7. A preparation method of a crystalline silicon battery using a copper wire as a main grid is characterized by comprising the following steps:

1) manufacturing fine grids on the front side and the back side of the battery piece through screen printing of silver paste;

2) directly and vertically placing a plurality of tinned alloy copper wires on the thin grids on the front side and the back side as main grids;

3) adhering the tinned alloy copper wire to the battery piece by using transparent hot melt adhesive to fix the copper wire; one end of a copper wire does not exceed the edge of the battery piece and is in contact with a thin grid on the outermost edge, the other end of the copper wire exceeds the edge of the battery piece and is welded to a tinned alloy copper piece serving as a bus bar, and one end of the bus bar in the length direction of the front face is connected with the outermost edge copper wire, and the other end of the bus bar in the length direction of the front face exceeds the edge of the battery piece after being connected with the outermost edge copper wire; on the back surface of the battery piece, one end of a copper wire does not exceed the edge of the battery piece and is in contact with a thin grid on the most edge, the other end of the copper wire exceeds the edge of the battery piece, one end of the copper wire exceeding the edge of the battery piece is welded on a tinned alloy copper piece serving as a bus bar, the length direction of the back bus bar is perpendicular to the copper wire, one ends of all the copper wires on the back surface, exceeding the edge of the battery piece, are in welded connection with the bus bar on the back surface, one end of the back bus bar in the length direction is connected with the most edge copper wire, and the other end of the back bus bar in the length; the bus bar on the front side and the bus bar on the back side of the battery piece are respectively positioned at two corresponding ends of the battery piece;

4) and heating, pressurizing and fixing the copper wire and the hot melt adhesive on the front surface of the battery piece and the copper wire and the hot melt adhesive on the back surface of the battery piece to form a battery unit.

8. The method for preparing the crystalline silicon battery with the copper wire as the main grid according to claim 7, wherein the steps 3) and 4) specifically comprise the following steps:

a) straightening all the tinned alloy copper wires and placing the tinned alloy copper wires along the direction of a fine grid vertical to the front side and the back side;

b) placing two transparent hot melt adhesives in a direction perpendicular to the copper wire, wherein the two transparent hot melt adhesives are respectively close to two edge positions of the battery piece;

c) pressing the hot melt adhesive, the copper wire and the battery piece by using pressure;

d) heating the battery piece, the copper wire and the hot melt adhesive together to a state that the hot melt adhesive is softened;

e) under the temperature and pressure, the battery piece and the copper wire are bonded together by the hot melt adhesive;

f) cooling, simultaneously removing pressure, solidifying the hot melt adhesive, and fixing the copper wire on the battery piece;

g) and welding bus bars to the extending ends of all the copper wires on the front surface and the back surface respectively.

9. The method for preparing a crystalline silicon battery with copper wires as a main grid according to claim 7, wherein in the step 3), the lengths of the other ends of the front copper wires and the back copper wires, which exceed the edges of the battery pieces, are 0.2-10 mm, and the copper wires exceeding the ends are welded to bus bars on the corresponding surfaces.

10. The method for preparing a crystalline silicon battery with a copper wire as a main grid according to claim 7, wherein in the step 3), the bus bars on the front side and the bus bars on the back side are both connected with the copper wire in a welding manner, and the copper wire is fixed on the battery piece by using hot melt adhesive; the distance from the side edge of the bus bar on the front side of the battery piece to the edge of the battery piece is 0-5 mm, the width of the bus bar is 1-10mm, the thickness of the bus bar is 0.05-0.2 mm, and the length of the other end of the bus bar in the length direction exceeding the edge of the battery piece is 1-10 mm; the distance from the side edge of the bus bar on the back surface of the battery piece to the edge of the battery piece is 0-5 mm, the width of the bus bar is 1-10mm, the thickness of the bus bar is 0.05-0.2 mm, and the length of the other end of the bus bar in the length direction exceeding the edge of the battery piece is 1-10 mm.

11. The method for preparing a crystalline silicon battery with the copper wire as the main grid according to claim 10, wherein in the step 4), the copper wire and the hot melt adhesive on the front surface of the battery piece and the copper wire and the hot melt adhesive on the back surface of the battery piece are heated, pressurized and fixed simultaneously; or the copper wire and the hot melt adhesive on the front surface of the battery piece and the copper wire and the hot melt adhesive on the back surface of the battery piece are respectively heated and pressurized for fixation; the bus bar is welded at the set position of the copper wire in advance, or the bus bar is welded at the set position of the copper wire after the copper wire is fixed to the battery piece through hot pressing.

12. A preparation method of a crystalline silicon battery component with a copper wire as a main grid is characterized by being manufactured by adopting the crystalline silicon battery with the copper wire as the main grid according to any one of claims 7 to 11, and comprising the following steps:

1) firstly, bending the excessive part of the back copper wire of one of two adjacent battery units by 180 degrees to enable the back copper sheet to be tightly attached to the back of the battery piece, then bending the front copper wire of the other battery unit in a Z shape to enable a front bus bar to be in series welding with the bus bar tightly attached to the back of the battery piece, and forming a group of battery units after series welding of a plurality of battery units;

2) the parts of the battery string units which are welded in series and the other battery string units which are arranged in parallel with the battery string units are mutually lap-welded and connected through the bus bars and extend out of the battery pieces;

3) two ends of the battery string are respectively connected to the main bus bars of the anode and the cathode of the assembly;

4) and adhering the front and back surfaces of the multiple groups of serially welded battery units to a layer of high-transparent glass or other back plate through a whole piece of hot melt adhesive with the area equivalent to that of the assembly to form the crystalline silicon battery assembly.

13. The method for preparing the crystalline silicon battery with the copper wires as the main grids according to claim 2 or 8, wherein in the step a), the number of the fine grids is 80-160, and the number of the copper wires as the main grids is 15-50; in the step b), the bandwidth of the hot melt adhesive is 1-10 mm.

14. The method for preparing a crystalline silicon battery with a copper wire as a main grid according to claim 2 or 8, wherein the hot melt adhesive is EVA or POE or PO polyethylene or PO polypropylene, and the hot melt obvious softening temperature is 80-180 ℃; the soldering tin plated on the copper wire is tin or an alloy of tin and one or more of lead, bismuth and silver, the welding melting point is 130-180 ℃, and the wire diameter is 0.05-0.3 mm.

Technical Field

The invention relates to the technical field of solar cells, in particular to a crystalline silicon cell using a copper wire as a main grid and a preparation method of a component of the crystalline silicon cell.

Background

The crystalline silicon photovoltaic cell (whether single-sided or double-sided has a grid line design) absorbs incident light through a cell, a charge separation layer is generated through a PN junction arranged on the surface, current is collected through a fine grid silver line arranged on a surface current splitting layer, one type of charge is collected on the front side, the other type of reverse charge is collected on the reverse side, and the charge separation layer is collected and led out through a main grid silver line.

At present, the conventional method is to manufacture the fine grid and the main grid by using silver paste respectively through a screen printing mode. The fine grid usually needs dozens to hundreds of fine grids, and the width of the fine grid is about 30-60 micrometers; the number of the main grid lines is usually 3-12, and the width is 500-2000 microns; the main grid is arranged perpendicular to the direction of the fine grid, and conductive contact is formed at the intersection of the main grid and the fine grid.

Several cells are series welded together to form an assembly by welding copper sheets (wires, filaments) plated with low temperature welding alloy to the main grid silver wires on the cells and connecting the front bonding wires of one cell to the back bonding wires of the adjacent cell, the series welding of the adjacent cells superposes the output voltages but the current is constant, so that the total power is superposed, the more cells are series welded, the higher the output power is, the cell series is laminated together through the packaging film, the cover glass and the back sheet to form an assembly, 60 cells are common (area 157 × 157 mm)²) The single crystal PERC battery component can reach about 320W.

With the arrival of the flat-price era, the overall investment cost of solar power generation can be reduced for crystalline silicon photovoltaic cells and modules by improving the photoelectric conversion efficiency and reducing the product cost. The silver paste is used for manufacturing the main grid and the fine grid, so that the cost is high, and the illumination area of the effective power generation cell is shielded, so that the generated energy is reduced.

In order to improve the photoelectric conversion efficiency, the HIT cell structure can achieve a better surface passivation effect, but the HIT cell structure can only be manufactured under the process condition of 200 ℃, so that silver paste cannot be sintered at high temperature after being printed on a cell piece, and the high-temperature sintering is beneficial to improving the conductivity of a silver lead so as to reduce the using amount. However, the HIT battery must use a low temperature silver paste, which has poor conductivity and requires an increased amount of silver paste.

In the process of collecting the current on the fine grid by the main grid, the larger the number of the main grids is, the shorter the transmission distance of the charges on the fine grid is, the lower the power loss is, the lower the conductivity requirement on the fine grid is, and thus, the silver consumption on the fine grid can be reduced. Recently, a multi-main grid technology is developed, and the number of original 5 main grids is increased to 9, even 12 main grids, so that the power loss can be reduced, the power generation capacity can be improved, and the silver consumption of fine grids can be reduced, which is particularly beneficial to HIT batteries.

However, the light shielding area is increased after the number of the main grids is increased, so the width of the main grids needs to be reduced, and the original flat welding strip with the width of 1-2 mm for 5 main grids can be changed into a round welding strip with the width of about 0.3mm, so the total coverage area is reduced. Moreover, the circular welding belt has another advantage that the reflection generated by the light irradiating on the arc-shaped surface can be reflected to the surface of the battery piece in the non-lead covering area through the upper glass cover plate to enter the battery so as to be utilized for generating power. The multi-main-grid and arc welding wire structure is beneficial to improving the power of the assembly by 5-15W.

However, even in the multi-main-grid scheme, the main-grid silver wire is necessary, otherwise, the round copper wire cannot be fixed on the battery piece. In order to solve the above problems, the MEYER BURGER (MEYER BURGER) invented a technical method called smart wire, which does not print the main grid of the silver wire, but the copper wire is designed and placed along the direction perpendicular to the thin grid and directly welded on the thin grid silver wire, thus saving the cost of the main grid silver wire. It can place more bonding wires (18-20) at the same time, so as to reduce the power loss and the conductive requirement for the fine grid silver wire. For the grid lines of the HIT battery, the cost of the high-efficiency battery is greatly reduced due to the reduction of the silver consumption.

However, the tension for soldering these fine copper wires to the secondary grid lines is too small to be easily achieved with conventional series soldering methods. Therefore, the Meiyangboge method is characterized in that copper wires are pre-laid on a polymer adhesive film plate, only thin grid lines are arranged on a battery, the polymer film plate with the copper wires is pressed on the battery piece to be laminated in the assembly manufacturing process, and the copper wires and the silver wires of the battery piece are welded together by vertically placing the copper wires and the thin grid lines at proper temperature and pressure in the assembly laminating process. Usually, the temperature of a bonding wire is about 160-180 ℃, the laminating temperature is 130-150 ℃, for this reason, the design needs to use a lower temperature copper wire, the welding temperature of the wire needs to be matched in a laminating way (130-150 ℃), and the temperature of the customized low temperature copper wire is 140 ℃. The process has the disadvantages that the laminating equipment is complicated, a special polymer film plate with low-temperature copper wires needs to be made in advance, special equipment suitable for the polymer film plate is purchased, and the comprehensive manufacturing cost is high.

In summary, the prior art solutions have the following disadvantages:

1. the conventional solder strip is soldered on the silver main grid, and the silver paste consumption of the main grid is large and the cost is high;

2. the laminating equipment adopting the Smart Wire method is complex, the investment cost is high, a special polymer copper Wire template and special equipment are needed, and the cost is correspondingly increased;

3. in addition, according to the current adjacent battery linking method, when sunlight is shaded (such as leaves or bird droppings are shielded), batteries without illumination cannot conduct electricity effectively (the characteristics of the batteries are that electricity is generated after illumination, the conductivity is greatly increased, and the reverse is not true), other batteries with illumination become heat energy when passing through the shadow, so that electricity cannot be generated, and the batteries are disabled (hot spot effect). Therefore, it is preferable that adjacent battery strings are connected by a wire so that when a battery on one string fails, current can be transmitted to another string in the periphery. However, the current series welding method has no effective method for electrically connecting adjacent battery strings.

Disclosure of Invention

In order to obtain an effective crystalline silicon cell unit, the invention provides a preparation method of a crystalline silicon cell using a copper wire as a main grid, which comprises the following steps:

1) manufacturing fine grids on the front side and the back side of the battery piece through screen printing of silver paste;

2) directly and vertically placing a plurality of tinned alloy copper wires on the thin grids on the front side and the back side as main grids;

3) adhering the tinned alloy copper wire to the battery piece by using transparent hot melt adhesive to fix the copper wire; one end of a copper wire does not exceed the edge of the battery piece and is in contact with a thin grid on the outermost edge on the front surface of the battery piece, the other end of the copper wire exceeds the edge of the battery piece and is welded on a tinned alloy copper piece serving as a bus bar, one end of the bus bar in the length direction on the front surface corresponds to the edge of the battery piece, and the other end of the bus bar exceeds the edge of the battery piece; on the back surface of the battery piece, two ends of a copper wire do not exceed the edges of the battery piece and are in contact with a thin grid on the outermost edge, one end of the copper wire is welded to a tinned alloy copper piece serving as a bus bar, the length direction of the bus bar on the back surface is perpendicular to the copper wire, one end of all the copper wires on the back surface is in welded connection with the bus bar, and the bus bar on the back surface and the bus bar on the front surface are respectively located at two corresponding ends of the battery piece;

4) and heating, pressurizing and fixing the bus bar, the copper wire and the hot melt adhesive on the back surface of the battery piece and the copper wire and the hot melt adhesive on the front surface of the battery piece to form a battery unit.

Wherein, the steps 3) and 4) specifically comprise the following steps:

a) straightening all the tinned alloy copper wires and placing the tinned alloy copper wires along the direction vertical to the front and back fine grids;

b) placing two transparent hot melt adhesives along the direction perpendicular to the copper wire, respectively approaching the two edges of the battery piece, and placing a bus bar on the back;

c) pressing the hot melt adhesive, the copper wire, the bus bar on the back and the battery piece by using pressure;

d) heating the battery piece, the copper wire, the bus bar on the back and the hot melt adhesive together to a state that the hot melt adhesive is softened;

e) under the temperature and pressure, the battery piece, the copper wire and the bus bar on the back are bonded together by the hot melt adhesive;

f) cooling, simultaneously removing pressure, solidifying the hot melt adhesive, and fixing the copper wires and the bus bars on the back surface on the battery piece;

g) and welding a bus bar on the front surface of all the extending ends of the copper wires.

In the step 3), the length of the other end of the copper wire on the front surface of the battery piece, which exceeds the edge of the battery piece, is 0.2-10 mm, the excess part of the copper wire is welded on the bus bar on the front surface, and the length of the other end of the bus bar on the front surface, which exceeds the edge of the battery piece, is 1-10 mm.

In the step 3), the bus bar on the back is in welding connection with the copper wire and is fixed on the battery piece by the hot melt adhesive, and the side edge of the bus bar does not exceed the edge of the battery piece; the distance from the outer side edge of the bus bar to the edge of the battery piece is 0-5 mm, the width of the bus bar is 1-10mm, and the thickness of the bus bar is 0.05-0.2 mm.

In the step 4), heating, pressurizing and fixing the bus bar, the copper wire and the hot melt adhesive on the back surface of the battery piece and the copper wire and the hot melt adhesive on the front surface of the battery piece at the same time; or the bus bar, the copper wire and the hot melt adhesive on the back surface of the battery piece and the copper wire and the hot melt adhesive on the front surface of the battery piece are respectively heated and pressurized for fixing.

Further, a preparation method of the crystalline silicon battery component with the copper wire as the main grid is manufactured by adopting the crystalline silicon battery unit with the copper wire as the main grid, and comprises the following steps:

1) firstly, bending the excessive part of the front copper wire of one of two adjacent battery units downwards and welding the excessive part of the front copper wire with the back copper wire of the other battery unit in series, and forming a group of battery units after the plurality of battery units are welded in series;

2) the parts of the battery string units which are welded in series and the other battery string units which are arranged in parallel with the battery string units are mutually lap-welded and connected through the parts of the bus bars on the front side, which extend out of the battery pieces;

3) two ends of the battery string are respectively connected to the main bus bars of the anode and the cathode of the assembly;

4) and adhering the front and back surfaces of the multiple groups of serially welded battery units to a layer of high-transparent glass or other back plate through a whole piece of hot melt adhesive with the area equivalent to that of the assembly to form the crystalline silicon battery assembly.

Or, after the 4 steps are performed by placing a plurality of battery unit positions in advance, the whole piece of hot melt adhesive and the whole piece of high-transparency glass are placed on the front surface and the back surface respectively to perform lamination to complete the manufacturing of the photovoltaic module at one time.

In order to obtain an effective crystalline silicon cell unit, the invention provides another preparation method of a crystalline silicon cell using a copper wire as a main grid, which comprises the following steps:

1) manufacturing fine grids on the front side and the back side of the battery piece through screen printing of silver paste;

2) directly and vertically placing a plurality of tinned alloy copper wires on the thin grids on the front side and the back side as main grids;

3) adhering the tinned alloy copper wire to the battery piece by using transparent hot melt adhesive to fix the copper wire; adhering the copper wire to the battery piece by using transparent hot melt adhesive to fix the copper wire; one end of a copper wire does not exceed the edge of the battery piece and is in contact with a thin grid on the outermost edge, the other end of the copper wire exceeds the edge of the battery piece and is welded to a tinned alloy copper piece serving as a bus bar, and one end of the bus bar in the length direction of the front face is connected with the outermost edge copper wire, and the other end of the bus bar in the length direction of the front face exceeds the edge of the battery piece after being connected with the outermost edge copper wire; on the back surface of the battery piece, one end of a copper wire does not exceed the edge of the battery piece and is in contact with a thin grid on the most edge, the other end of the copper wire exceeds the edge of the battery piece, one end of the copper wire exceeding the edge of the battery piece is welded on a tinned alloy copper piece serving as a bus bar, the length direction of the back bus bar is perpendicular to the copper wire, one ends of all the copper wires on the back surface, exceeding the edge of the battery piece, are in welded connection with the bus bar on the back surface, one end of the back bus bar in the length direction is connected with the most edge copper wire, and the other end of the back bus bar in the length; the bus bar on the front side and the bus bar on the back side of the battery piece are respectively positioned at two corresponding ends of the battery piece;

4) and heating, pressurizing and fixing the copper wire and the hot melt adhesive on the front surface of the battery piece and the copper wire and the hot melt adhesive on the back surface of the battery piece to form a battery unit.

Wherein, the steps 3) and 4) specifically comprise the following steps:

a) straightening all the tinned alloy copper wires and placing the tinned alloy copper wires along the direction of a fine grid vertical to the front side and the back side;

b) placing two transparent hot melt adhesives in a direction perpendicular to the copper wire, wherein the two transparent hot melt adhesives are respectively close to two edge positions of the battery piece;

c) pressing the hot melt adhesive, the copper wire and the battery piece by using pressure;

d) heating the battery piece, the copper wire and the hot melt adhesive together to a state that the hot melt adhesive is softened;

e) under the temperature and pressure, the battery piece and the copper wire are bonded together by the hot melt adhesive;

f) cooling, simultaneously removing pressure, solidifying the hot melt adhesive, and fixing the copper wire on the battery piece;

g) and welding bus bars to the extending ends of all the copper wires on the front surface and the back surface respectively.

In the step 3), the lengths of the other ends of the front copper wire and the back copper wire exceeding the edges of the battery pieces are 0.2-10 mm, and the copper wires exceeding the parts are welded to the bus bars of the corresponding surfaces.

In the step 3), the bus bars on the front side and the bus bars on the back side are both connected with copper wires in a welding manner, and the copper wires are fixed on the battery pieces by hot melt adhesive; the distance from the side edge of the bus bar on the front side of the battery piece to the edge of the battery piece is 0-5 mm, the width of the bus bar is 1-10mm, the thickness of the bus bar is 0.05-0.2 mm, and the length of the other end of the bus bar in the length direction exceeding the edge of the battery piece is 1-10 mm; the distance from the side edge of the bus bar on the back surface of the battery piece to the edge of the battery piece is 0-5 mm, the width of the bus bar is 1-10mm, the thickness of the bus bar is 0.05-0.2 mm, and the length of the other end of the bus bar in the length direction exceeding the edge of the battery piece is 1-10 mm.

In the step 4), the copper wire and the hot melt adhesive on the front surface of the battery piece and the copper wire and the hot melt adhesive on the back surface of the battery piece are heated, pressurized and fixed simultaneously; or the copper wire and the hot melt adhesive on the front surface of the battery piece and the copper wire and the hot melt adhesive on the back surface of the battery piece are respectively heated and pressurized for fixation; the bus bar is welded at the set position of the copper wire in advance, or the bus bar is welded at the set position of the copper wire after the copper wire is fixed to the battery piece through hot pressing.

Further, a method for manufacturing a crystalline silicon battery assembly with a copper wire as a main grid, which is manufactured by using the crystalline silicon battery unit with the copper wire as the main grid, according to the claim, comprises the following steps:

1) firstly, bending the excessive part of the back copper wire of one of two adjacent battery units by 180 degrees to enable the back copper sheet to be tightly attached to the back of the battery piece, then bending the front copper wire of the other battery unit in a Z shape to enable a front bus bar to be in series welding with the bus bar tightly attached to the back of the battery piece, and forming a group of battery units after series welding of a plurality of battery units;

2) the parts of the battery string units which are welded in series and the other battery string units which are arranged in parallel with the battery string units are mutually lap-welded and connected through the bus bars and extend out of the battery pieces;

3) two ends of the battery string are respectively connected to the main bus bars of the anode and the cathode of the assembly;

4) and adhering the front and back surfaces of the multiple groups of serially welded battery units to a layer of high-transparent glass or other back plate through a whole piece of hot melt adhesive with the area equivalent to that of the assembly to form the crystalline silicon battery assembly.

Or, after the copper wire at the back exceeds the part and is bent for 180 degrees so that the bus bar at the back is tightly attached to the back of the cell, the whole piece of hot melt adhesive and high-transparency glass with the area equivalent to that of the assembly are respectively placed on the front side and the back side to be laminated to complete the manufacture of the photovoltaic assembly at one time.

In the two battery structure schemes, in the step a), the number of the fine grids is 80-160, and the number of the copper wires serving as the main grids is 15-50; in the step b), the bandwidth of the hot melt adhesive is 1-10 mm.

In the two battery structure schemes, the hot melt adhesive is EVA or POE or PO polyethylene or PO polypropylene, and the obvious softening temperature of the hot melt is 80-180 ℃; the soldering tin plated on the copper wire is tin or an alloy of tin and one or more of lead, bismuth and silver, the welding melting point is 130-180 ℃, and the wire diameter is 0.05-0.3 mm.

In addition, all solar cells and modules with double surfaces needing main grid lines to collect current, such as PERC, TOPCon, HIT and the like, are prepared according to the two battery units and modules.

Through the technical scheme, the invention is a novel battery design. The crystalline silicon battery is characterized in that a main grid is fixed on a silicon wafer in advance through transparent hot melt adhesive, then copper wires and thin grid silver wires are welded under certain pressure and heating, and all the copper wires on the front side and the back side are respectively welded on a bus bar. When the assembly is formed, the bus bars on the front surface and the bus bars on the back surface of the adjacent batteries are welded to form battery strings, and meanwhile, the adjacent battery strings can be mutually welded through the parts extending out of the bus bars. Because the copper wire is fixed by the hot melt adhesive, the problem that the copper wire and the thin grid silver wire are easy to fall off during welding is solved, the copper wire does not need to be attached to the polymer film-coated template in advance, the material cost is reduced, and the process is simplified.

According to the invention, the welding copper wires are used for manufacturing the main grid, so that the silver paste consumption for manufacturing the battery is reduced, and the output power of the photovoltaic module is increased; meanwhile, the hot spot problem can be prevented and solved through the connection of the battery strings.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below.

FIG. 1 is a schematic diagram of a crystalline silicon cell with fine grids printed but without a main grid according to an embodiment of the disclosure;

fig. 2 is a schematic cross-sectional view of a battery cell disclosed in example 1;

fig. 3 is a schematic front view of a battery cell as disclosed in example 1;

fig. 4 is a schematic view of the back of a battery cell disclosed in example 1;

fig. 5 is a schematic view of series welding connection of the battery cells disclosed in example 1;

fig. 6 is a schematic cross-sectional view of a battery assembly made of the battery cell disclosed in example 2;

FIG. 7 is a schematic cross-sectional view of a battery cell disclosed in example 3;

FIG. 8 is a schematic cross-sectional view of a battery cell as disclosed in example 5;

FIG. 9 is a schematic cross-sectional view of a battery cell disclosed in example 7;

fig. 10 is a schematic illustration of back side parallel lap welding of adjacent cells as disclosed in example 1;

fig. 11 is a schematic view of the front side parallel lap welding of adjacent battery cells disclosed in examples 2, 3 and 5.

The reference numbers in the figures denote: 10. a battery piece; 11. fine grids; 12. a main grid; 121. a tail portion; 13. hot melt adhesive; 14. a bus bar; 20. high-transparency glass; A. an edge; B. and (7) lap welding.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.