WO2023016582A1

WO2023016582A1 - Photovoltaic cell string and manufacturing method therefor, string soldering device, and photovoltaic assembly

Info

Publication number: WO2023016582A1
Application number: PCT/CN2022/124915
Authority: WO
Inventors: 黄耀纶
Original assignee: 中能创光电科技(常州)有限公司
Priority date: 2021-08-13
Filing date: 2022-10-12
Publication date: 2023-02-16
Also published as: CN115706182A

Abstract

The present invention relates to a photovoltaic cell string, a manufacturing method therefor, a string soldering device, and a photovoltaic assembly. In the photovoltaic cell string, a photovoltaic cell of said string is connected to an adjacent photovoltaic cell by means of a multiple main-grid interconnection structure composed of main grid lines and auxiliary lines, the multiple main-grid interconnection structure being connected to the photovoltaic cells by means of connection points. The preparation method comprises: first, wiring auxiliary lines to main grid lines to form a multiple main-grid interconnection structure, and wiring the multiple main-grid interconnection structure to the surface of a first photovoltaic cell; wiring auxiliary lines on the back surface of a second photovoltaic cell to main grid lines, and connecting the second photovoltaic cell to the multiple main-grid interconnection structure. The string soldering device comprises an additional auxiliary line wiring mechanism and an auxiliary line soldering mechanism. The photovoltaic module comprises the described photovoltaic cell string and a packaging material for packaging the photovoltaic cell string. The beneficial effects are: owing to the auxiliary line design, fewer connection points are needed to maintain the stability of the position of the main grid lines, thereby greatly reducing Ag slurry consumption.

Description

Photovoltaic cell string and its preparation method, string welding equipment and photovoltaic module

technical field

The invention relates to the field of photovoltaic technology, in particular to a photovoltaic cell string, a preparation method thereof, string welding equipment and a photovoltaic module.

Background technique

In recent years, the application of photovoltaic new energy has developed rapidly. Combined with energy storage, electric vehicles, charging piles and other technologies, the new model will realize the local consumption of photovoltaic power generation. Therefore, roof distributed and building-integrated photovoltaics (BIPV) will become the next focus of photovoltaic applications.

Due to the limited application area of rooftop photovoltaic and BIPV, more efficient cells and modules are required. Among the next-generation batteries, the most promising new batteries should be TOPCON and heterojunction batteries. Among the next-generation module technologies, shingled modules have the highest module efficiency.

At present, these three technologies all have the problem of high cost. Compared with the mainstream PREC technology, the Ag slurry consumption of the heterojunction cell increases by 150%, and the Ag slurry consumption of the TOPCON cell increases by 50%. When these batteries are combined with shingled technology for module packaging, the consumption of Ag paste will further increase.

How to reduce the consumption of Ag paste is the core bottleneck for the development of the photovoltaic industry and the development of BIPV rooftop photovoltaics. Can it reduce the consumption of Ag slurry and make high-efficiency battery components good and cheap? This is the biggest challenge for the PV industry right now.

Existing photovoltaic cells can be divided into photovoltaic cells with main grid and photovoltaic cells without main grid according to the presence or absence of main grid. The main grid lines of the battery extend in the second direction, and the surface of the photovoltaic cell without main grid has only the thin grid lines of the battery extending in the second direction.

The multi-busbar photovoltaic technology solution usually refers to the interconnection of photovoltaic cells through more than 6 busbar ribbons, which can not only reduce the shading of the surface of photovoltaic cells, increase the light-receiving area, reduce the distance that current passes in the fine grid, but also effectively reduce the cost of components. The series resistance reduces the current carried by each main gate, the resistance loss is smaller, and the conversion efficiency is higher. The photovoltaic cells used in the multi-busbar photovoltaic technology scheme can be photovoltaic cells with or without busbars. The multi-busbar ribbons used are usually tinned copper ribbons. Compared with traditional flat ribbons, the diameter is very small. Small, the welding alignment is difficult.

Figure 1 shows a photovoltaic cell string in a common multi-busbar photovoltaic module. The photovoltaic cell used is a photovoltaic cell with a busbar. On the surface of the photovoltaic cell, there is a battery composed of Ag paste corresponding to the multi-busbar ribbon. Main grid, in order to save Ag paste, the main grid of the battery adopts the design of the main grid of the thin battery. Ag paste materials are used for the pads and the main grid of the fine battery. For a 9BB multi-busbar photovoltaic cell with 9 thin battery busbars, the battery busbar paste accounts for about 40% of the Ag paste consumption, which is an important source of battery paste cost.

Compared with the traditional busbar photovoltaic cells, busbar-free photovoltaic cells can achieve the effect of reducing the consumption of Ag paste because of the saving of battery busbar lines, thereby reducing the cost.

However, the existing multi-busbar photovoltaic technology solution using busbar-free photovoltaic cells still has the problem of high cost, as follows:

There are two existing multi-busbar photovoltaic module technologies using busbar-free photovoltaic cells. The first one is represented by the busbar-free photovoltaic cell technology disclosed in Chinese patent document CN104716213B. The surface of the wire directly forms a good conductor contact with the metal fine grid line (Ag fine grid line). This method effectively removes the battery busbar and saves battery Ag consumption. However, the cost of the conductive adhesive coated on the multi-busbar Cu strips is relatively high, which hinders the final cost reduction effect.

The second is based on the smart wire technology of Meyer Burger, Switzerland. By adding a layer of adhesive film, the multi-busbar Cu strip is adhered to the adhesive film, and then the Cu strip is fixed on the surface of the battery with the adhesive film to form a Cu strip. Good conductive contact with metal fine grid lines/conductive film. The disadvantage of this solution is that the price of this layer of adhesive film is too high, and at the same time it increases the cost of the process, and the effect of actually reducing the cost is limited.

Contents of the invention

The technical problem to be solved by the present invention is to provide a photovoltaic battery string, its preparation method and photovoltaic module, so as to solve the problem of high metallization cost of the photovoltaic battery module.

The technical solution adopted by the present invention to solve the technical problem is: a photovoltaic cell string, including two adjacent photovoltaic cells, the adjacent two photovoltaic cells are divided into a first photovoltaic cell and a second photovoltaic cell, and the photovoltaic cells are The busbar-free photovoltaic cell, the surface of the first photovoltaic cell has a multi-busbar interconnection structure, and the multi-busbar interconnection structure has n1 conductive busbar lines extending along the first direction and arranged at intervals along the second direction and along the second n2 auxiliary lines extending in the direction, the auxiliary lines are connected with the n1 main grid lines as a whole, and one side of the n1 main grid lines has an extension section extending from the surface of the first photovoltaic cell for connecting with the adjacent second The photovoltaic cells are connected, and the multi-busbar interconnection structure is connected to the surface of the first photovoltaic cell through n3 conductive or non-conductive connection points, n1≥2, n2≥1, n3≥2.

The material of the auxiliary line is metal or non-metal.

Once the n1 busbar lines are combined into a whole through the auxiliary lines, only a small number of connection points are needed to stably fix the entire multi-busbar interconnection structure on the surface of the photovoltaic cell.

This technical solution is generally applicable to various high-efficiency batteries, such as common heterojunction batteries, passivated contact TOPCON batteries, back-junction IBC batteries, perovskite batteries, and other laminated batteries of thin film and crystalline silicon. It is especially beneficial to implement on heterojunction cells, and close the material cost gap between heterojunction cells and conventional PERC cells.

It is further defined that the extension of one side of the n1 main grid lines is directly welded to the back electrode of the opposite polarity surface of the second photovoltaic cell, the main grid line is a welding strip, and the back electrode refers to the main grid of the battery on the back of the photovoltaic cell or full back electrode.

Or, there are n4 auxiliary lines extending along the second direction on the extension section of one side of the n1 main grid lines, and the n4 auxiliary lines are connected with the n1 main grid lines as a whole, and the multi-main grid interconnection structure and the second The opposite polarity surfaces of the photovoltaic cells are connected through n5 conductive or non-conductive connection points, n4≥1, n5≥2.

It is further defined that on the surface of the first photovoltaic cell, at least one auxiliary wire is located at the end of the n1 main grid lines, and on the surface of the second photovoltaic cell, at least one auxiliary wire is located at the extension of the n1 main grid lines end position.

Further defined, the main grid line is located between the auxiliary line and the photovoltaic cell.

It is further defined that the auxiliary lines and the main grid lines form a connection relationship at intersections by means of welding or bonding. The connection points between the multi-busbar interconnection structure and the surface of the first photovoltaic cell are formed by welding or bonding. Welding includes alloy heat welding, ultrasonic welding, friction welding, resistance welding and laser welding, etc. Bonding includes hot melt adhesive bonding, silicone bonding, acrylic adhesive bonding, UV adhesive bonding and epoxy adhesive bonding, etc.

It is further defined that the auxiliary line at the end of the n1 busbar lines is a bent part of a busbar line arranged on the outermost side.

It is further defined that the main grid line is a low-temperature soldering strip, the welding temperature of the low-temperature soldering strip matches the lamination temperature of the photovoltaic module, and is used to form a welding connection with the photovoltaic cell at the lamination temperature of the photovoltaic module, and the auxiliary line is a metal wire, Solder ribbon, transparent or non-transparent plastic wire. The solder ribbon is a metal wire with a solder coating on its surface.

When the auxiliary line is a polymer material plastic line, such as polyamide, linear polycarbonate, polymethyl methacrylate, polypropylene, polystyrene, polyethylene terephthalate and other materials, laser can be used The welding process (the automobile industry has mature technology), firstly uses laser to form a microstructure on the surface of the busbar, and then combines it with the polymer material. The process of this method is more complicated, but polymer materials have certain cost advantages. In addition, polymer materials can be transparent, which has certain advantages in terms of optical shading loss.

When the auxiliary wire and the main grid wire are common tin-coated copper strips, the welding between the auxiliary wire and the main grid wire is very simple, and a very strong alloy can be formed by various methods such as hot air, infrared, hot pressing, induction heating, etc. Cross welding points. The above-mentioned alloy welding method is simple, easy to operate, and very practical.

It is further defined that the multi-busbar interconnection structure is connected to the surface of a photovoltaic cell through at least 3 connection points, of which 2 connection points are located on the auxiliary line at the end of the busbar line, and the other connection point is located on the photovoltaic cell. the middle of the other edge.

It is further defined that the surface of the photovoltaic cell has a pad or a sticky pad, which is used to form a connection point with a multi-bus grid interconnection structure, and the pad is an Ag paste pad, an Ag/Cu paste pad, an Ag/Sn paste pad, or an Al paste pad. Pads, AgAl paste pads, Ni paste pads or AgNi paste pads, the pads are conductive or non-conductive, specifically EVA hot-melt adhesive pads, acrylic adhesive pads, epoxy adhesive pads or those mixed with conductive particles Conductive adhesive sticky disc.

The welding pad or sticking pad can make the bonding force between the multi-busbar interconnection structure and the surface of the photovoltaic cell between 1 and 3N. Make the main grid line and the conductive layer on the surface of the photovoltaic cell (such as the conductive layer on the surface of the heterojunction battery, indium tin oxide ITO) or/and the thin grid line of the battery obtain better contact and good conductivity in the subsequent component packaging process .

A method for preparing a photovoltaic cell string. The photovoltaic cell string is the above-mentioned photovoltaic cell string. The front side of the first photovoltaic cell is connected to the opposite polarity back side of the second photovoltaic cell through a multi-busbar interconnection structure, and n1 busbar lines There are n4 auxiliary wires extending along the second direction on the extension section of one side, the n4 auxiliary wires are connected with the n1 busbar lines as a whole, and the multi-busbar interconnection structure is opposite to the polarity of the second photovoltaic cell on the back side Connect through n5 conductive or non-conductive connection points, n4≥1, n5≥2, the surfaces of the first photovoltaic cell and the second photovoltaic cell have pads or sticky pads, which are used to form connection points with the multi-busbar interconnection structure , has the following steps: a) Wiring the auxiliary wires on the front side of the first photovoltaic cell to n1 busbar lines, and connecting with n1 busbar lines to form a multi-busbar interconnection structure, and then connecting the multi-busbar interconnection structure Wiring to the front side of the first photovoltaic cell, connecting the multi-busbar interconnection structure with the pads or bonding pads on the front side of the first photovoltaic cell by welding or bonding, or first interconnecting the multi-busbars through a pressing part The structure is temporarily pressed on the front side of the first photovoltaic cell, and then in step b together with the second photovoltaic cell, the multi-busbar interconnection structure is connected to the pads or adhesive pads on the front side of the first photovoltaic cell by welding or adhesive curing together; b) wiring the auxiliary line on the back of the second photovoltaic cell to the extension of n1 main grid lines, and connecting with n1 main grid lines, and then placing the second photovoltaic cell on the n1 main grid lines The multi-busbar interconnection structure is connected to the pads or bonding pads on the back side of the second photovoltaic cell by welding or bonding.

A string welding equipment for photovoltaic cell strings, used to prepare the above-mentioned photovoltaic cell strings, including a string welding workbench, a main grid wiring mechanism and an auxiliary wire wiring mechanism. The grid limiting groove is vertical to the auxiliary line limiting groove. The main grid wiring mechanism is used to route n1 main grid lines to the front of the photovoltaic cell. The auxiliary line wiring mechanism is used to route the auxiliary lines above the n1 main grid lines. There is a movable main grid lifting mechanism under the grid limiting groove, and an auxiliary wire welding mechanism is above the auxiliary wire limiting groove.

It is further defined that an auxiliary wire jacking mechanism is provided below the auxiliary wire limiting groove. The auxiliary wire jacking mechanism is used to push out the auxiliary wire located in the auxiliary wire limiting groove.

For the photovoltaic cell strings prepared by the photovoltaic cell string stringing equipment, the auxiliary lines are located above the main grid lines, and another photovoltaic cell string stringing equipment is provided below, which can route the auxiliary lines below the main grid lines. The difference of the photovoltaic cell string string welding equipment is that: there are two auxiliary wire jacking mechanisms that can move left and right under the auxiliary wire limiting groove, and are used to store the auxiliary wire on one of the auxiliary wire jacking mechanisms; or, There is a wire storage type jacking mechanism below the auxiliary line limit groove, the auxiliary line is stored in the storage type jacking mechanism, and the stored auxiliary line is sent out when needed.

A photovoltaic module, comprising the above-mentioned photovoltaic cell string and an encapsulation material for encapsulating the photovoltaic cell string, the encapsulation material includes a hot-melt film, the hot-melt film is fully or partially pre-crosslinked, and the pre-crosslinked hot-melt film connects n1 busbars The wires are pressed tightly on the surface of the photovoltaic cell; or, the thermosol film and the photovoltaic cell are separated by a film that will not melt when laminated and packaged, and the thermosol film compresses the n1 main grid lines on the photovoltaic cell through the film. s surface.

The beneficial effect of the invention is that: the design of the auxiliary line enables the stability of the position of the main grid line to be maintained with fewer connection points, and the consumption of Ag paste can be greatly reduced.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the present invention is further described;

Fig. 1 is a structural schematic diagram of a photovoltaic cell string of an existing multi-busbar photovoltaic module;

Fig. 2 is a schematic structural diagram of an existing busbar heterojunction photovoltaic cell;

FIG. 3 is a schematic structural view of an existing busbar-free heterojunction photovoltaic cell;

Fig. 4 is the structural representation of the photovoltaic cell string of embodiment 1 of the present invention;

Fig. 5a is a schematic structural diagram of the first working state of the stringing equipment for photovoltaic cell strings according to Embodiment 1 of the present invention;

Fig. 5b is a schematic structural diagram of the second working state of the stringing equipment for photovoltaic cell strings according to Embodiment 1 of the present invention;

Fig. 5c is a schematic diagram of the structure of the first working state of the photovoltaic cell string stringing equipment used in Embodiment 1 of the present invention to store auxiliary lines;

Fig. 5d is a schematic diagram of the structure of the second working state of the photovoltaic battery string stringing equipment used in Embodiment 1 of the present invention to store auxiliary lines;

Fig. 6 is a schematic structural view of a photovoltaic cell string according to Embodiment 2 of the present invention;

Fig. 7 is a structural schematic diagram of a photovoltaic cell string according to Embodiment 3 of the present invention;

Fig. 8 is a schematic structural view of a photovoltaic cell string according to Embodiment 4 of the present invention;

Fig. 9a is a schematic diagram of the front structure of the photovoltaic cell string according to Embodiment 5 of the present invention;

Fig. 9b is a schematic side view of the first photovoltaic cell and the second photovoltaic cell shingle in the photovoltaic cell string according to Embodiment 5 of the present invention;

Fig. 10 is a schematic structural view of a busbar-free heterojunction photovoltaic cell in Example 7 of the present invention;

Fig. 11 is a schematic structural diagram of a photovoltaic cell string according to Embodiment 8 of the present invention;

Fig. 12 is a schematic structural view of a photovoltaic cell string according to Embodiment 9 of the present invention;

Fig. 13 is a schematic structural view of a photovoltaic cell string according to Embodiment 10 of the present invention;

In the figure, 1. The first photovoltaic cell, 1-1. Thin-film coating on the surface of the battery, 1-2. N-type silicon wafer substrate, 1-3. Thin-film coating on the back of the battery, 1-4. Busbar of the battery, 1-5 .Battery thin grid line, 1-6. Composite metal coating, 2. Second photovoltaic cell, 3. Main grid line, 3-1. Flattened section, 4-1. First auxiliary line, 4-2. Second Auxiliary line, 5. Welding pad, 6. Adhesive plate, 7. Serial welding table, 7-1. Main grid limit groove, 7-2. Auxiliary line limit groove, 8-1. Main grid traction mechanism, 8 -2. Main grid cutting mechanism, 8-3. Main grid clamping mechanism, 9-1. Auxiliary wire pulling mechanism, 9-2. Auxiliary wire cutting mechanism, 9-3. Auxiliary wire clamping mechanism, 9-4. Steering wheel, 10. Auxiliary line jacking mechanism.

Detailed ways

Example 1, a common heterojunction photovoltaic cell, as shown in Figure 2, belongs to a photovoltaic cell with a busbar, including a thin film coating on the surface of the battery 1-1, an N-type silicon substrate 1-2, and a thin film coating on the back of the battery 1-3 1. The battery main grid lines 1-4 and battery fine grid lines 1-5 of the Ag paste material on the front and back of the battery, the battery thin grid lines 1-5 on the back of the battery are not visible in the figure, and the thin film coating on the battery surface 1-1 is generally It is an amorphous silicon/doped Si/ITO conductive thin film coating on the surface of the silicon wafer, and the thin film coatings 1-3 on the back of the battery are generally amorphous silicon/doped silicon/ITO thin film coatings.

Fig. 3 is the busbar-free heterojunction photovoltaic cell used in Example 1, and the polarity of the front and back of the photovoltaic cell is opposite. Different from the conventional battery in FIG. 2 , firstly, the battery busbars 1-4 on the front and back of the battery are removed, thus saving the corresponding Ag paste consumption and cost.

As shown in Figure 4, a photovoltaic cell string includes two adjacent photovoltaic cells, and the adjacent two photovoltaic cells are divided into a first photovoltaic cell 1 and a second photovoltaic cell 2, and the photovoltaic cell is as shown in Figure 3 Busbar-free heterojunction photovoltaic cells, the front of the first photovoltaic cell 1 has a multi-busbar interconnection structure, and the front side of the first photovoltaic cell 1 is connected to the opposite polarity back of the second photovoltaic cell 2 through the multi-busbar interconnection structure , the multi-busbar interconnection structure has n1 conductive busbar lines 3 extending along the first direction and arranged at intervals along the second direction and auxiliary lines extending along the second direction, one auxiliary line on the front side of the first photovoltaic cell 1 The line is located at the end of the n1 main grid lines 3, the auxiliary line is connected with the n1 main grid lines 3 as a whole, and one side of the n1 main grid lines 3 has an extension section extending from the surface of the first photovoltaic cell 1 , used to connect to the back of the adjacent second photovoltaic cell 2, the multi-busbar interconnection structure is connected to the front of the first photovoltaic cell 1 through n3 conductive or non-conductive connection points, n1≥2, n3≥2 . There is also an auxiliary line extending along the second direction on the extension section of one side of the n1 main grid lines 3, the auxiliary line is located at the end of the extension section of the n1 main grid lines 3, and the auxiliary line is also Connected with n1 busbar lines 3 as a whole, the multi-busbar interconnection structure is connected to the surface opposite to the polarity of the second photovoltaic cell 2 through n5 conductive or non-conductive connection points, n5≥2.

In industrialized production, the number n1 of busbar lines 3 is usually designed to be 9-50. In the first embodiment, n1=18, the main gate line 3 and the two auxiliary lines at both ends are connected at the intersections by welding to form an integral multi-main gate interconnection structure.

The multi-busbar photovoltaic technical solution of Embodiment 1 makes the increase in the number of busbars 3 no longer lead to an increase in the consumption of battery busbars 1-4 and corresponding Ag paste. At the same time, the increase in the number of busbars 3 will shorten the furthest distance from the battery fine gridlines 1-5 to the busbars 3, thereby reducing the conductive requirements of the battery finer gridlines 1-5 and the corresponding consumption of Ag paste.

The distance between the first photovoltaic cell 1 and the second photovoltaic cell 2 may be a large distance of 2 mm to 3 mm, or a small distance of 0.5 mm to 1 mm.

The busbar 3 is a low-temperature soldering strip whose welding temperature matches the lamination temperature of the photovoltaic module, and is used to form a welding connection with the photovoltaic cell at the lamination temperature of the photovoltaic module.

The surface of the photovoltaic cell has a pad 5, and the pad 5 is an Ag paste pad, an Ag/Cu paste pad, an Ag/Sn paste pad, an Al paste pad, an AgAl paste pad, a Ni paste pad or an AgNi paste pad. The pads, the multi-busbar interconnection structure and the pads 5 on the surfaces of the first photovoltaic cell 1 and the second photovoltaic cell 2 form connection points by welding.

6 black squares on the first photovoltaic cell 1 in Fig. 4 are printed with the pads 5 of the Ag paste material, and the 6 hollow squares in Fig. 4 correspond to the pads 5 of the Ag paste material on the back side of the photovoltaic cell Location.

Compared with the conventional multi-busbar design shown in Figure 1, each photovoltaic cell needs 2×180 pads 5 on the front and back sides, and each pad 5 needs to be connected with thin battery busbar lines 1-4. With the design of the present invention, in the example shown in FIG. 4 , the number of welding pads 5 on the front and back sides of each photovoltaic cell is reduced to 2×6, which is reduced to 3.3% of the original. In theory, each cell weighs about 10 grams. In principle, only two pads 5 are needed to fix it (2N corresponds to the gravity of a photovoltaic cell of 200 grams). The design of using six pads 5 on each side fully considers the process Window and redundant design to ensure reliability.

A preparation method of the photovoltaic cell string of the present embodiment 1 has the following steps:

a) Wiring the auxiliary lines on the front side of the first photovoltaic cell 1 to n1 busbar lines 3, and connecting them to n1 busbar lines 3 to form a multi-busbar interconnection structure, and then wiring the multi-busbar interconnection structure to On the front side of the first photovoltaic cell 1, connect the multi-busbar interconnection structure with the pad 5 on the front side of the first photovoltaic cell 1 by welding, or temporarily press the multi-busbar interconnection structure on the front side of the first photovoltaic cell 1 through a pressing member. The front side of the first photovoltaic cell 1, and then in step b together with the second photovoltaic cell 2, the multi-busbar interconnection structure is connected to the pad 5 on the front side of the first photovoltaic cell 1 by welding;

b) Wiring the auxiliary line on the back of the second photovoltaic cell 2 to the extension of n1 main grid lines 3, and connecting with n1 main grid lines 3, and then placing the second photovoltaic cell 2 on the n1 main grid lines On the extended section of the line 3, the multi-busbar interconnection structure is connected to the pad 5 on the back side of the second photovoltaic cell 2 by welding.

As shown in Figures 5a and 5b, a kind of stringing equipment for the photovoltaic cell string of the present embodiment 1 includes a stringing workbench 7, a main grid wiring mechanism and an auxiliary wire wiring mechanism, and on the stringing workbench 7 there are The main grid limiting slot 7-1 and the auxiliary line limiting slot 7-2 perpendicular to the main grid limiting slot 7-1, the main grid wiring mechanism is used to route n1 main grid lines 3 to the front of the photovoltaic cell, and the auxiliary line The wiring mechanism is used for wiring the auxiliary lines above the n1 main gate lines 3 . There is a movable main grid jacking mechanism under the main grid limiting groove 7-1, an auxiliary wire welding mechanism is installed above the auxiliary wire limiting groove 7-2, and an auxiliary wire jacking mechanism is provided under the auxiliary wire limiting groove 7-2. Agency10.

The stringing workbench 7, the main grid wiring mechanism, and the movable jacking mechanism below the main grid limiting groove 7-1 are the existing components of the existing photovoltaic cell string stringing equipment, and the difference from the existing stringing equipment In that: the auxiliary wire limiting groove 7-2, the auxiliary wire wiring mechanism, the auxiliary wire jacking mechanism 10 below the auxiliary wire limiting groove 7-2 and the auxiliary wire welding mechanism are added for wiring and welding of the auxiliary wire, The auxiliary wire jacking mechanism 10 is basically the same in structure and function as the movable main grid jacking mechanism, except that the auxiliary wire jacking mechanism 10 does not need to move left and right in this embodiment.

The main grid wiring mechanism includes a main grid pulling mechanism 8-1, a main grid cutting mechanism 8-2, and a main grid clamping mechanism 8-3, and the auxiliary wire wiring mechanism includes an auxiliary wire pulling mechanism 9-1 and an auxiliary wire cutting mechanism 9-2 , Auxiliary line clamping mechanism 9-3 and steering wheel 9-4.

The main grid limiting groove 7-1 and the auxiliary line limiting groove 7-2 are concave strip-shaped grooves on the surface of the serial welding workbench 7, and are used to respectively limit the main grid line 3 and the auxiliary line.

The head of the busbar pulling mechanism 8-1 has the function of clamping the busbar 3. The busbar pulling mechanism 8-1 clamps the head end of the busbar 3, and pulls the busbar 3 to the surface of the photovoltaic cell by moving.

The busbar cutting mechanism 8 - 2 is a cutting mechanism that can cut off the busbar lines 3 .

The busbar clamping mechanism 8 - 3 is located behind the busbar pulling mechanism 8 - 1 , and is used for clamping the busbar 3 at the outlet end of the busbar 3 .

The busbar 3 passes through the busbar clamping mechanism 8-3, the busbar cutting mechanism 8-2 and the busbar pulling mechanism 8-1 in sequence from back to front.

The auxiliary line welding mechanism is specifically a welding press block, and the welding press block cooperates with the auxiliary line jacking mechanism 10 to weld the auxiliary line and the main grid line together.

Auxiliary wire pulling mechanism 9-1, auxiliary wire cutting mechanism 9-2, auxiliary wire clamping mechanism 9-3 and main grid pulling mechanism 8-1, main grid cutting mechanism 8-2, main grid clamping mechanism 8-3 structure The same as the function, but the wiring direction is different, the steering wheel 9-4 is used to change the traction direction of the auxiliary line. The auxiliary wire pulling mechanism 9-1 is located on one side of the series welding workbench 7, and the auxiliary wire cutting mechanism 9-2, the auxiliary wire clamping mechanism 9-3 and the main grid pulling mechanism 8-1 are located on the other side of the series welding workbench 7. side. After the auxiliary line is turned by the steering wheel 9-4, it passes through the auxiliary line clamping mechanism 9-3, the auxiliary line cutting mechanism 9-2 and the auxiliary line pulling mechanism 9-1 from back to front.

The process of preparing the photovoltaic cell string of the present embodiment 1 through the string welding equipment of the photovoltaic cell string is as follows:

1. As shown in FIG. 5a, firstly, the 18 busbars 3 are pulled to the position shown in FIG. 5a along the first direction by the busbar pulling mechanism 8-1. The busbar 3 is a Cu soldering strip coated with Sn47Bi52Ag1, and its diameter is 0.25mm.

2. In the second direction perpendicular to the 18 main grid lines 3, pull the first auxiliary wire 4-1 into the auxiliary wire limiting groove 7-2 of the serial welding workbench 7 through the auxiliary wire pulling mechanism 9-1, The first auxiliary line 4 - 1 is routed above the previous 18 main gate lines 3 and vertically crosses the main gate lines 3 . The auxiliary wire is made of metal materials, such as tin-coated copper strip, tin-coated aluminum strip, tin-coated iron strip, etc.

3. Through the cooperation of the welding press block above the auxiliary wire limiting groove 7-2 and the auxiliary wire jacking mechanism 10 below the auxiliary wire limiting groove 7-2, heat and melt the Sn47Bi52Ag coating on the surface of the main grid wire 3, and place the second An auxiliary wire 4-1 is welded and connected with 18 main grid wires 3 as a whole.

4. Clamp the auxiliary thread at the auxiliary thread clamping mechanism 9-3, and cut the required length of the auxiliary thread through the auxiliary thread cutting mechanism 9-2. The auxiliary line clamping mechanism 9-3 fixes the thread ends of the remaining auxiliary lines, so that the auxiliary line clamping mechanism 9-3 can pull out a new auxiliary line again. The busbar 3 is clamped at the busbar clamping mechanism 8-3, and the busbar 3 of required length is cut by the busbar cutting mechanism 8-2. The busbar clamping mechanism 8-3 fixes the ends of the remaining busbar lines 3, so that the busbar clamping mechanism 8-3 can pull out new busbar lines 3 again.

5. Then, the busbar pulling mechanism 8-1 continues to pull the 18 busbar lines 3 to the left to a proper position on the front of the first photovoltaic cell 1 . The main grid line 3 and the first auxiliary line 4-1 have been integrated. In the process of moving to the left, the main grid line 3 also drives the first auxiliary line 4 - 1 to the front side of the first photovoltaic cell 1 as shown in FIG. 5 b . In order to make it easier to see the key details, Fig. 5b does not draw the main grid limiting groove 7-1 and the auxiliary line limiting groove 7-2.

6. Press a pressing part, specifically a limit pressing block (not shown in the figure, which is an existing conventional technology) on the front of the first photovoltaic cell 1, and temporarily press 18 main grid lines 3 on the front of the first photovoltaic cell. Front side of battery 1. At this time, the positions of the 18 busbar lines 3 and the first auxiliary lines 4 - 1 correspond to the pads 5 on the front side of the first photovoltaic cell 1 .

7. Route the second auxiliary wire 4-2 on the back of the second photovoltaic cell 2 to the top of the 18 main grid wires 3: the auxiliary wire bypasses the steering wheel 9-4 to change the pulling direction of the auxiliary wire, and the auxiliary wire passes through the auxiliary wire The clamping mechanism 9-3 is drawn to the required length by the auxiliary line pulling mechanism 9-1, and the auxiliary line clamping mechanism 9-3 clamps one end of the auxiliary line. The auxiliary thread is cut off by the auxiliary thread cutting mechanism 9-2, and falls into the auxiliary thread limiting groove 7-2 to be positioned.

8. Repeat step 3 to weld and connect the second auxiliary wire 4-2 and the 18 busbar wires 3 into one.

9. Put the second photovoltaic cell 2 on the string welding workbench 7 by the manipulator.

10. The movable jacking mechanism below the main grid limit groove 7-1 pushes up the 18 main grid lines 3 and the second auxiliary wire 4-2, and lifts the 18 main grid lines 3 and the second auxiliary wire 4-2 Press on the back of the second photovoltaic cell 2, and move the first photovoltaic cell 1 and the second photovoltaic cell 2 that have completed the wiring of the multi-busbar interconnection structure to the left by one station by moving horizontally to the left, and move the second photovoltaic cell 2 Move to the previous position of the first photovoltaic cell 1. The previous first photovoltaic cell 1 enters the welding area for welding, so that the multi-busbar interconnection structure and the pad 5 on the surface of the photovoltaic cell are welded together.

11. Repeat steps 1 to 10 to complete the string welding of photovoltaic cells to become a string of photovoltaic cells.

For the photovoltaic cell string prepared by the above-mentioned string welding equipment for photovoltaic cell strings, the auxiliary lines are located above the main grid line 3, and another string welding equipment for photovoltaic cell strings is provided below, which can connect the second auxiliary line on the back of the second photovoltaic cell Line 4 - 2 is routed under busbar line 3 .

Specifically, on the basis of the above-mentioned stringing equipment for photovoltaic cell strings, the bottom of the auxiliary line limiting groove 7-2 is replaced with two auxiliary line jacking mechanisms 10 that can move left and right, and are used to store the auxiliary line in one of them. On the auxiliary thread jacking mechanism 10, a storage slot can be set on the auxiliary thread jacking mechanism 10 for storing auxiliary threads, so that the auxiliary thread can be stored on the auxiliary thread jacking mechanism 10 more stably, before step 1 First store the second auxiliary line 4-2 in one of the auxiliary line jacking mechanisms 10, as shown in Figure 5c, then move the auxiliary line jacking mechanism 10 to one side to realize the storage of the auxiliary line, and the other auxiliary line jacking mechanism 10 is moved to below the auxiliary line limiting slot 7-2 for the wiring of the first auxiliary line 4-1, as shown in FIG. 5d. After steps 1 to 6 are completed, the auxiliary wire lifting mechanism 10 storing the second auxiliary wire 4-2 is moved below the auxiliary wire limiting groove 7-2, so that the wiring of the second auxiliary wire 4-2 to the main gate line 3 is realized. Below, instead of step 7.

Of course, it is also possible to have a wire storage type jacking mechanism below the auxiliary line limiting groove 7-2, the auxiliary line is stored in the wire storage type jacking mechanism, and the stored auxiliary line is sent out when needed. Before step 1, store the second auxiliary line 4-2 in the wire storage type jacking mechanism. To achieve the same function as the common auxiliary thread jacking mechanism 10, after completing steps 1 to 6, the storage type jacking mechanism storing the second auxiliary thread 4-2 sends out the stored second auxiliary thread 4-2 to realize the second auxiliary thread 4-2. The two auxiliary lines 4 - 2 are routed under the main gate line 3 .

A photovoltaic module, including the photovoltaic cell string of this embodiment 1 and an encapsulation material for encapsulating the photovoltaic cell string, the encapsulation material includes a hot-melt film, the hot-melt film is pre-crosslinked in all or part of the area, and the pre-crosslinked part of the area is specifically For the area facing the photovoltaic cell, the pre-crosslinked hot-sol film presses n1 busbars 3 on the surface of the photovoltaic cell. Alternatively, the hot-melt film and the photovoltaic cell are separated by a thin film that will not melt during lamination and packaging, and the hot-melt film presses the n1 busbars 3 on the surface of the photovoltaic cell through the thin film.

In this embodiment 1, the busbar 3 is a low-temperature solder ribbon. When the photovoltaic cell string is encapsulated in the packaging material through a lamination process, the welding coating on the surface of the busbar 3 will melt, and the battery thin film on the surface of the photovoltaic cell will melt. The gate lines 1-5 form a welding relationship to realize conductive connection. Of course, it is not excluded that when the busbar 3 is a metal wire without solder coating, the busbar 3 is pressed against the thin gridline by the pressing force of the pre-crosslinked hot melt film or film to realize contact conduction.

Embodiment 2, as shown in FIG. 6, is a photovoltaic cell string, which is basically the same as the photovoltaic cell string in Embodiment 1. The middle part of the wire 3 has a progressive flattened section 3 - 1 , and the flattened section 3 - 1 extends from the edge of the first photovoltaic cell 1 to the edge of the second photovoltaic cell 2 .

Embodiment 3, as shown in FIG. 7 , a photovoltaic cell string is basically the same as the photovoltaic cell string in Embodiment 2, the difference is that the auxiliary line on the back of the second photovoltaic cell 2 is a wide auxiliary line, for example, a thickness of 0.10mm is used. , a 1mm wide ribbon to reduce the alignment accuracy requirements for backside welding.

Embodiment 4, as shown in FIG. 8 , is a photovoltaic cell string, which is basically the same as the photovoltaic cell string in Embodiment 2, except that the auxiliary lines are formed in a different way. The auxiliary line at the end of the busbar 3 is a bent part of the outermost busbar 3 , and the bent part is welded to the other 17 busbars 3 .

The main grid lines 3 are welding strips, and one of the uppermost edges of the 18 main grid lines 3 is bent to become an auxiliary line, and forms a welding relationship with the other 17 main grid lines 3 through the welding coating on the surface.

Embodiment 5, as shown in Figures 9a and 9b, a photovoltaic cell string is basically the same as the photovoltaic cell string in Embodiment 3, the difference is that the first photovoltaic cell 1 and the second photovoltaic cell 2 are shingled interconnected structures, and the second There is a negative distance between a photovoltaic cell 1 and a second photovoltaic cell 2 . Since the overlapping bonding of adjacent photovoltaic cells also has the effect of fixing the main grid lines 3 , compared with Embodiment 3, the number of pads 5 can be further reduced.

The front side of the first photovoltaic cell 1 still has 6 connection points, 3 of which are located at the intersection of the first auxiliary line 4-1 and the main grid line 3, specifically the pad 5, and the other 3 are located at the adjacent photovoltaic cell The overlapping part is specifically the sticky disc 6, where the material of the sticky disc 6 is a dispensing material, which is silica gel commonly used in shingled components, and does not contain Ag material. The back of the second photovoltaic cell 2 is reduced to 3 connection points.

Embodiment 6, a photovoltaic cell string, is basically the same as the photovoltaic cell string in Embodiment 1, the difference is that the bonding pad 5 on the surface of the photovoltaic cell is replaced by a bonding pad 6, which is used to form a connection point with a multi-busbar interconnection structure. The adhesive disc 6 is an EVA hot-melt adhesive disc, an acrylic adhesive disc or an epoxy adhesive disc.

Compared with the conventional multi-busbar design shown in Figure 1, Examples 1 to 5 can reduce the Ag paste consumption of the battery busbar by more than 95%, and the corresponding total Ag paste consumption can be reduced by at least 40%, which is very significant Improve. However, by adopting the non-conductive pad 6 method of the present embodiment 6, the pad 5 of precious metal material can be removed 100%, and the precious metal material can be completely saved.

Embodiment 7, a photovoltaic cell string, is basically the same as the photovoltaic cell string in Embodiment 1, the difference lies in that the structure of the busbar-free heterojunction photovoltaic cell is different. As shown in Figure 10, the photovoltaic cell is a single-sided cell. The front of the photovoltaic cell has no main grid structure, and the back electrode on the back is a composite metal coating 1-6 on the entire surface, such as a composite film of Sn, Ni, Cu, Al, etc., which is a full back electrode form. There may be local discontinuity in the middle of the composite metal coating 1-6 to release stress. More specifically, the cell used in this embodiment is a 158×158mm heterojunction photovoltaic cell, the number of thin grid lines 1-5 on the front of the photovoltaic cell is 85, and the total Ag paste consumption is 60mg. The back of the photovoltaic cell uses a sputtered metal Cu/Sn film, the thickness of the Cu film is about 1000nm, and the thickness of the Sn film is about 100nm.

The extensions on one side of the 85 busbars 3 on the front of the first photovoltaic cell 1 are directly welded to the composite metal plating 1-6 on the back of the second photovoltaic cell 2 without using the pad 5 for connection.

Embodiment 8, as shown in Figure 11, is a photovoltaic cell string, which is basically the same as the photovoltaic cell string in Embodiment 1, the difference is that the first auxiliary wire 4-1 and the second auxiliary wire 4-2 are made of polyamide material become. The surface of the busbar 3 is firstly pretreated by laser, and then the laser welding of the busbar 3 and the first auxiliary line 4-1 and the second auxiliary line 4-2 is performed. The connection point on the surface of the photovoltaic cell is the adhesive disc 6, and the first auxiliary line 4-1 and the second auxiliary line 4-2 are bonded and fixed by hot melt adhesive, and there is no cross relationship between the connection point and the main grid line 3, which can avoid Possibly poor electrical conduction of components, during quality inspection, it will appear as poor black line detected by electroluminescence EL.

Embodiment 9, as shown in FIG. 12 , is a photovoltaic cell string, which is basically the same as the photovoltaic cell string in Embodiment 1, except that the multi-busbar interconnection structure is connected to one photovoltaic cell through two connection points. In the accompanying drawing 12, both the front of the first photovoltaic cell 1 and the back of the second photovoltaic cell 2 have two adhesive pads 6 for connecting with the auxiliary lines of the multi-busbar interconnection structure, the front of the first photovoltaic cell 1 and the back of the second photovoltaic cell 2 The back of the second photovoltaic cell 2 has two auxiliary wires, and the two auxiliary wires are located on the left and right sides of the photovoltaic cell.

Embodiment 10, as shown in Figure 13, is a photovoltaic cell string, which is basically the same as the photovoltaic cell string in Embodiment 1, the difference is that the auxiliary line on the surface of the photovoltaic cell is located in the middle of the photovoltaic cell, and the multi-busbar interconnection structure passes through 2 connection points are connected to a photovoltaic cell. Under the inventive idea of the present invention, there are other different specific embodiments, such as changing the specific material of the auxiliary line, such as changing the specific physical position of the pad 5 or the sticky pad 6, such as changing the welding of the pad 5 and the sticky pad 6 Material components, bonding material components, such as changing the shape of the auxiliary line to triangle, trapezoid, semicircle, square, sheet, etc., such as changing the battery thin grid lines 1-5 of photovoltaic cells to copper grid, aluminum grid, silver copper Hybrid grids, etc., such as changing the material of the main grid lines 3 to copper, iron, aluminum, silver, etc., all belong to the protection scope of the present invention.

Claims

A photovoltaic cell string, comprising two adjacent photovoltaic cells, the two adjacent photovoltaic cells are divided into a first photovoltaic cell and a second photovoltaic cell, the photovoltaic cell is a photovoltaic cell without main grid, and the surface of the first photovoltaic cell has The multi-main gate interconnection structure is characterized in that: the multi-main gate interconnection structure has n1 conductive main gate lines extending along the first direction and arranged at intervals along the second direction, and n2 auxiliary main gate lines extending along the second direction. line, the auxiliary line is connected with the n1 main grid lines as a whole, and one side of the n1 main grid lines has an extension section extending from the surface of the first photovoltaic cell for connecting with the adjacent second photovoltaic cell,

The multi-busbar interconnection structure is connected to the surface of the first photovoltaic cell through n3 conductive or non-conductive connection points,

n1≥2, n2≥1, n3≥2.
The photovoltaic cell string according to claim 1, characterized in that: the extension section on one side of the n1 main grid lines is directly welded to the back electrode on the opposite surface of the second photovoltaic cell, and the main grid lines For the ribbon;

Alternatively, there are n4 auxiliary lines extending along the second direction on the extension section of one side of the n1 main grid lines, and the n4 auxiliary lines are connected with the n1 main grid lines as a whole, and the multi-main gate interconnection structure The surface opposite to the polarity of the second photovoltaic cell is connected by n5 conductive or non-conductive connection points, n4≥1, n5≥2.
The photovoltaic cell string according to claim 2, characterized in that: on the surface of the first photovoltaic cell, at least one auxiliary wire is located at the end of the n1 main grid lines, and on the surface of the second photovoltaic cell, at least one The auxiliary lines are located at the ends of the extensions of the n1 main grid lines.
The photovoltaic cell string according to claim 1, characterized in that: the main grid line is located between the auxiliary line and the photovoltaic cell.
The photovoltaic cell string according to claim 1, characterized in that: the auxiliary wire and the main grid wire form a connection relationship at the intersection by welding or bonding,

The connection points between the multi-busbar interconnection structure and the surface of the photovoltaic cell are formed by welding or bonding.
The photovoltaic cell string according to claim 1, wherein the auxiliary wire at the end of the n1 main grid lines is a bent part of the outermost one of the main grid lines.
The photovoltaic cell string according to claim 1, characterized in that: the busbar is a low-temperature soldering strip, and the welding temperature of the low-temperature soldering strip matches the lamination temperature of the photovoltaic module, and is used for the lamination temperature of the photovoltaic module. Form a welding connection relationship with the photovoltaic cell,

The auxiliary wires are metal wires, welding ribbons, transparent or non-transparent plastic wires.
The photovoltaic cell string according to claim 3, characterized in that: the multi-busbar interconnection structure is connected to the surface of a photovoltaic cell through at least 3 connection points, wherein 2 connection points are located at the ends of the busbar lines On the auxiliary line at the upper position, another connection point is located in the middle of the other side edge of the photovoltaic cell.
The photovoltaic cell string according to claim 1, characterized in that: the surface of the photovoltaic cell has a pad or a sticky pad for forming a connection point with a multi-bus grid interconnection structure, and the pad is an Ag paste pad, an Ag paste pad, or an Ag pad. /Cu paste pad, Ag/Sn paste pad, Al paste pad, AgAl paste pad, Ni paste pad or AgNi paste pad, the sticky pad is conductive or non-conductive, specifically EVA hot-melt adhesive pad, acrylic Adhesive discs, epoxy adhesive discs or conductive adhesive discs mixed with conductive particles.
A method for preparing a photovoltaic cell string, characterized in that: the photovoltaic cell string is the photovoltaic cell string described in claim 1, and the front side of the first photovoltaic cell is connected to the polarity of the second photovoltaic cell through a multi-bus grid interconnection structure. On the opposite side for connection, the extension on one side of the n1 main gate lines has n4 auxiliary lines extending along the second direction, and the n4 auxiliary lines are connected with the n1 main gate lines as a whole, and the multi-main gate interconnection structure The reverse side of the polarity opposite to the second photovoltaic cell is connected through n5 conductive or non-conductive connection points, n4≥1, n5≥2, the surfaces of the first photovoltaic cell and the second photovoltaic cell have pads or adhesive pads, Used to form a connection point with a multi-busbar interconnection structure,

It has the following steps: a) wiring the auxiliary lines on the front side of the first photovoltaic cell to n1 busbar lines, and connecting them with n1 busbar lines to form a multi-busbar interconnection structure, and then wiring the multi-busbar interconnection structure To the front side of the first photovoltaic cell, connect the multi-busbar interconnection structure with the pads or adhesive pads on the front side of the first photovoltaic cell by welding or bonding, or firstly connect the multi-busbar interconnection structure Temporarily press on the front side of the first photovoltaic cell, and then in step b together with the second photovoltaic cell, connect the multi-busbar interconnection structure to the pads or adhesive pads on the front side of the first photovoltaic cell by welding or bonding and curing. Together;

b) Wiring the auxiliary line on the back of the second photovoltaic cell to the extension of n1 main grid lines, and connecting with n1 main grid lines, and then placing the second photovoltaic cell on the extension of n1 main grid lines On the upper side, the multi-busbar interconnection structure is connected to the pads or bonding pads on the back of the second photovoltaic cell by welding or bonding.
A string welding equipment for photovoltaic cell strings, used to prepare the photovoltaic cell strings according to claim 1, characterized in that: it includes a string welding workbench, a main grid wiring mechanism and an auxiliary line wiring mechanism, and the string welding workbench has The main grid limiting slot and the auxiliary line limiting slot perpendicular to the main grid limiting slot, the main grid wiring mechanism is used to route n1 main grid lines to the front of the photovoltaic cell, and the auxiliary line wiring mechanism is used to route the auxiliary lines to n1 There is a movable busbar lifting mechanism above the main busbar line and below the main grid limiting slot, and an auxiliary line welding mechanism is above the auxiliary line limiting slot.
The photovoltaic cell string string welding equipment according to claim 11, characterized in that: there is an auxiliary wire jacking mechanism under the auxiliary wire limiting groove;

Alternatively, there are two auxiliary line jacking mechanisms that can move left and right under the auxiliary line limiting groove, for storing the auxiliary line on one of the auxiliary line jacking mechanisms;

Alternatively, there is a storage type jacking mechanism below the auxiliary line limiting groove, the auxiliary line is stored in the storage type jacking mechanism, and the stored auxiliary line is sent out when needed.
A photovoltaic module, characterized in that: comprising the photovoltaic cell string described in claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 and the encapsulation material for encapsulating the photovoltaic cell string, the encapsulation material includes a hot-melt film , the thermal sol film is pre-crosslinked in whole or in part, and the pre-crosslinked thermal sol film compresses n1 busbars on the surface of the photovoltaic cell;

Alternatively, the hot-melt film and the photovoltaic cell are separated by a thin film that will not melt during lamination and packaging, and the hot-melt film presses the n1 busbars on the surface of the photovoltaic cell through the thin film.