A double-sided battery, its manufacturing method, and packaging process

Abstract

The present invention discloses a PERC double-sided battery, wherein a plurality of the back grid lines are horizontally spaced apart, and the back grid lines are formed by alternately connecting a plurality of back silver grid lines and a plurality of back aluminum grid lines to form the back structure of the PERC double-sided battery. The present invention also discloses a method for manufacturing a PERC double-sided battery, which includes performing laser treatment at corresponding positions to obtain positioning Marking points; precisely aligning and printing the back silver grid lines through a first printing screen plate with the positioning Marking points; precisely aligning and printing the back aluminum grid lines through a second printing screen plate with the positioning Marking points; and printing the front grid lines on the front side of the battery. The front side of the double-sided battery of the present invention adopts a main gridless design, which reduces the usage amount of silver paste. The back side adopts a new grid line structure design, and only silver grid lines are used at the wire bonding contact positions on the back side of the battery, and aluminum grid lines are used for the remaining areas that do not contact the wire bonding to obtain the PERC double-sided battery, which can greatly reduce the paste cost of the PERC battery.

Description

Technical Field

[0001] The present invention relates to the technical field of the production of solar photovoltaic cells and the encapsulation and manufacturing of components, and specifically to a PERC double-sided cell, its manufacturing method, and encapsulation process. Background Art

[0002] The encapsulation technology for reducing the production cost of photovoltaic cells and improving the power of components is the most effective method for promoting photovoltaic energy. Among them, reducing the amount of paste used in the manufacturing process of photovoltaic cells is one of the most direct methods for reducing the manufacturing cost of photovoltaic cells.

[0003] Currently, the design and production of PERC cells are all calculated to match traditional welding component encapsulation technology. Considering that a certain area of the welding surface is required for the welding process to contact the welding wire to meet the welding requirements, the paste cost of photovoltaic cells is relatively high.

[0004] In the prior art, the front electrode structure of a solar cell with the authorized publication number CN203312312U includes a frame and a front electrode of the cell. The front electrode of the cell includes main grid lines and sub-grid lines. The main grid lines are longitudinally spaced apart, and the sub-grid lines are cross-distributed with the main grid lines. The main grid lines are in an intermittent structure, and each intermittent main grid line is connected by a welding wire. Auxiliary grid lines parallel to the main grid lines are provided between adjacent main grid lines. This technical solution improves the overall performance of the solar cell on the basis of saving raw materials and reducing costs.

[0005] However, the above electrode structure still has the following defects and problems in terms of the technical aspects of saving raw materials and reducing costs. The setting method of the main grid lines is still adopted, which will consume a large amount of main grid silver paste and greatly increase the paste cost of PERC cells. Summary of the Invention

[0006] The purpose of the present invention is to provide a PERC double-sided cell, its manufacturing method, and encapsulation process to solve the problems raised in the above background art.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] A PERC double-sided cell includes a plurality of front grid lines provided on the front of the cell and a plurality of back grid lines provided on the back of the cell. The plurality of back grid lines are horizontally spaced apart, and the back grid lines are formed by alternately connecting a plurality of back silver grid lines and a plurality of back aluminum grid lines to form the back structure of the PERC double-sided cell.

[0009] Preferably, a printing overlap area is provided at the connection of the back silver grid line and the back aluminum grid line.

[0010] Preferably, both ends of the back grid line are provided with back aluminum grid lines.

[0011] Preferably, both ends of the back gate line are provided as back silver gate lines.

[0012] Preferably, one end of the back gate line is provided as a back silver gate line and the other end is provided as a back aluminum gate line.

[0013] Preferably, one side of several back gate lines is provided as back silver gate lines from top to bottom.

[0014] Preferably, one side of several back gate lines is arranged at intervals of back silver gate lines and back aluminum gate lines from top to bottom.

[0015] A method for manufacturing the PERC double-sided battery includes the following steps:

[0016] 1) Using single-crystalline and polycrystalline silicon wafers to obtain a good textured surface structure through surface texturing;

[0017] 2) Cleaning the liquid remaining during texturing;

[0018] 3) Reacting phosphorus oxychloride with the silicon wafer to obtain phosphorus atoms. After a certain time, the phosphorus atoms enter the surface layer of the silicon wafer and penetrate and diffuse into the silicon wafer through the gaps between silicon atoms, forming an interface between N-type semiconductors and P-type semiconductors;

[0019] 4) Removing the edge PN junction through plasma etching to avoid short circuits at the edges;

[0020] 5) Since the diffusion junction formation process will form a layer of phosphosilicate glass on the surface of the silicon wafer, the impact on the efficiency of the shingled battery is reduced through the phosphosilicate glass removal process;

[0021] 6) Depositing a certain thickness of aluminum oxide passivation layer on the back of the battery by ALD or PERC method;

[0022] 7) Depositing a silicon nitride antireflection film with one or more layers of structure on the back, and completing the preparation of the antireflection film through the PECVD chemical vapor deposition process;

[0023] 8) Depositing a silicon nitride antireflection film with one or more layers of structure on the front of the battery, and completing it through the PECVD chemical vapor deposition process;

[0024] It also includes:

[0025] 9) Laser grooving the back of the battery and performing laser treatment at corresponding positions to obtain positioning Marking points;

[0026] 10) Using a CCD camera to capture the positioning Marking points and performing precision alignment printing of the back silver gate lines through a printing screen and the positioning Marking points;

[0027] 11) Use a two-channel CCD camera to capture the positioning Marking points after the first printing, and perform precision alignment printing of the back aluminum grid lines through the second printing screen and the positioning Marking points, and ensure that the back aluminum grid lines and the back silver grid lines are alternately connected to each other;

[0028] 12) Print the front grid lines on the front of the battery and perform sintering tests.

[0029] A PERC double-sided battery module encapsulation process for the PERC double-sided battery described above, comprising the following steps:

[0030] 1) Use one end of a metal wire bond to perform alignment interconnection with the back silver grid line of the battery, and the other end of the metal wire bond to perform interconnection with the front grid line of another battery;

[0031] 2) Connect the battery cells in sequence according to the positive and negative poles to form a battery string, and perform layout and lamination on the battery string;

[0032] 3) Laminate the laminated battery string and perform framing tests on the laminated parts to complete the component encapsulation production. Compared with the prior art, the beneficial effects of the present invention are:

[0033] The front of the solar cell of the present invention adopts a non-main grid design, which reduces the usage amount of silver paste. The back adopts a new grid line design structure, and only silver grid lines are used at the wire bond contact positions on the back of the battery, and aluminum grid lines are used for the remaining areas that do not contact the wire bonds to obtain a PERC double-sided battery. This can greatly reduce the paste cost of the PERC battery, improve the conversion efficiency of the battery at the same time, and the PERC double-sided battery of the present invention, combined with the new wire bond interconnection encapsulation technology, can improve the power of the module. Description of the Drawings

[0034] Figure 1 It is a schematic structural diagram of Embodiment 1 in which both ends of the back grid line are set as back aluminum grid lines in the present invention;

[0035] Figure 2 is Figure 1 The enlarged schematic diagram of the structure of Area A in;

[0036] Figure 3 It is a schematic structural diagram of Embodiment 2 in which both ends of the back grid line are set as back silver grid lines in the present invention;

[0037] Figure 4 It is a schematic structural diagram of Embodiment 3 in which the two ends of the back grid line are respectively set as back silver grid lines and back aluminum grid lines in the present invention;

[0038] Figure 5 It is a schematic structural diagram of Embodiment 4 in which the two ends of the back grid line are respectively set as back silver grid lines and back aluminum grid lines in the present invention;

[0039] Figure 6 Schematic diagram of printing the back silver grid line structure during the manufacturing method of the double-sided battery of the present invention;

[0040] Figure 7 Schematic diagram of printing the back aluminum grid line structure during the manufacturing method of the double-sided battery of the present invention;

[0041] Figure 8 Schematic diagram of the front grid line structure of the double-sided battery of the present invention;

[0042] Figure 9 Schematic diagram of the connection structure between the metal wire bond and the back silver grid line in the first embodiment of the present invention;

[0043] Figure 10 is Figure 9 Enlarged schematic diagram of the structure of area B in;

[0044] Figure 11 Schematic diagram of the connection structure between the metal wire bond and the front grid line of the battery.

[0045] In the figure: 1 front grid line, 2 back grid line, 3 back silver grid line, 4 back aluminum grid line, 5 metal wire bond, 6 printing overlap area, 7 positioning Marking point. Specific implementation manner

[0046] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0047] Please refer to Figure 1-11 , the present invention provides a technical solution:

[0048] Embodiment 1: A PERC double-sided battery includes a plurality of front grid lines 1 provided on the front of the battery and a plurality of back grid lines 2 provided on the back of the battery. The plurality of back grid lines 2 are horizontally spaced apart. The back grid lines 2 are alternately connected by a plurality of back silver grid lines 3 and a plurality of back aluminum grid lines 4 to form the back structure of the PERC double-sided battery. A printing overlap area 6 is provided at the connection of the back silver grid line 3 and the back aluminum grid line 4, which can ensure a better connection effect between the back silver grid line 3 and the back aluminum grid line 4. The adjacent back silver grid lines 3 are connected by a metal wire bond 5;

[0049] As shown in the attached Figure 1 of the specification, both ends of the back grid line 2 are set as back aluminum grid lines 4, and both ends of the back grid line 2 in contact with the battery cell frame are back aluminum grid lines 4. As shown in the attached Figure 9As shown, the back silver grid lines 3 in the up and down directions are on the same vertical line and are used for welding connection by the metal bonding wires 5.

[0050] Embodiment 2: A PERC double-sided battery includes a plurality of front grid lines 1 provided on the front of the battery and a plurality of back grid lines 2 provided on the back of the battery. The plurality of back grid lines 2 are horizontally spaced apart. The back grid lines 2 are formed by alternately connecting a plurality of back silver grid lines 3 and a plurality of back aluminum grid lines 4. A printing overlap area 6 is provided at the connection of the back silver grid lines 3 and the back aluminum grid lines 4, which can ensure better connection effect between the back silver grid lines 3 and the back aluminum grid lines 4. The adjacent back silver grid lines 3 in the up and down directions are connected by metal bonding wires 5.

[0051] As shown in the Figure 3 specification appendix, both ends of the back grid line 2 are set as back silver grid lines 3. Both ends of the back grid line 2 in contact with the battery cell frame are back silver grid lines 3. The back silver grid lines 3 in the up and down directions are on the same vertical line and are used for welding connection by the metal bonding wires 5.

[0052] Embodiment 3: A PERC double-sided battery includes a plurality of front grid lines 1 provided on the front of the battery and a plurality of back grid lines 2 provided on the back of the battery. The plurality of back grid lines 2 are horizontally spaced apart. The back grid lines 2 are formed by alternately connecting a plurality of back silver grid lines 3 and a plurality of back aluminum grid lines 4. A printing overlap area 6 is provided at the connection of the back silver grid lines 3 and the back aluminum grid lines 4, which can ensure better connection effect between the back silver grid lines 3 and the back aluminum grid lines 4. The adjacent back silver grid lines 3 in the up and down directions are connected by metal bonding wires 5.

[0053] As shown in the Figure 4 specification appendix, one end of the back grid line 2 is set as a back silver grid line 3 and the other end is set as a back aluminum grid line 4. Among the two ends of the back grid line 2 in contact with the battery cell frame, one end is a back silver grid line 3 and the other end is a back aluminum grid line 4. All the left sides of the plurality of back grid lines 2 from top to bottom are set as back silver grid lines 3. The connection ends of the right side of the back grid line 2 with the frame are all set as back aluminum grid lines 4. The back silver grid lines 3 in the up and down directions are on the same vertical line and are used for welding connection by the metal bonding wires 5.

[0054] Embodiment 4: A PERC double-sided battery includes a plurality of front grid lines 1 provided on the front of the battery and a plurality of back grid lines 2 provided on the back of the battery. The plurality of back grid lines 2 are horizontally spaced apart. The back grid lines 2 are formed by alternately connecting a plurality of back silver grid lines 3 and a plurality of back aluminum grid lines 4. A printing overlap area 6 is provided at the connection of the back silver grid lines 3 and the back aluminum grid lines 4, which can ensure better connection effect between the back silver grid lines 3 and the back aluminum grid lines 4. The adjacent back silver grid lines 3 in the up and down directions are connected by metal bonding wires 5.

[0055] As shown in the Figure 5As shown, one end of the back grid line 2 is set as the back silver grid line 3, and the other end is set as the back aluminum grid line 4. Among the two ends where the back grid line 2 contacts the cell frame, one end is the back silver grid line 3, and the other end is the back aluminum grid line 4. Among several back grid lines 2, on one side, the back silver grid lines 3 and the back aluminum grid lines 4 are arranged at intervals from top to bottom. At the connection ends of the right or left side of the back grid line 2 with the frame, the back silver grid lines 3 and the back aluminum grid lines 4 are arranged alternately in sequence. The adjacent back silver grid lines 3 in the up and down directions are arranged staggeredly. The back silver grid line 3 is used for welding and connection by the metal wire 5.

[0056] A method for manufacturing a PERC double-sided cell includes the following steps:

[0057] 1) Using single-crystalline or polycrystalline silicon wafers to obtain a good textured surface structure through surface texturing, so as to increase the specific surface area to accept more photons and energy, and at the same time reduce the reflection of incident light;

[0058] 2) Cleaning the residual liquid during texturing to reduce the influence of acidic and alkaline substances on cell junction formation;

[0059] 3) Reacting phosphorus oxychloride with the silicon wafer to obtain phosphorus atoms. After a certain time, the phosphorus atoms enter the surface layer of the silicon wafer and penetrate and diffuse into the silicon wafer through the gaps between silicon atoms, forming an interface between the N-type semiconductor and the P-type semiconductor, completing the diffusion junction formation process, realizing the conversion of light energy to electrical energy, and increasing the SE process flow;

[0060] 4) Since the diffusion junction formation forms a short-circuit channel at the edge of the silicon wafer, the photo-generated electrons collected on the front side of the PN junction will flow along the edge region with phosphorus to the back side of the PN junction, resulting in a short circuit. Therefore, the edge PN junction is etched away through plasma etching to avoid short circuits at the edge;

[0061] 5) Since the diffusion junction formation process will form a layer of phosphosilicate glass on the surface of the silicon wafer, the influence on the efficiency of the shingled cell is reduced through the phosphosilicate glass removal process;

[0062] 6) Using the ALD or PERC method to deposit a certain thickness of aluminum oxide passivation layer on the back side of the cell;

[0063] 7) In order to protect the passivation layer, a silicon nitride antireflection film with one or more layers of structure needs to be deposited on the back side, and the preparation of the antireflection film is completed through the PECVD chemical vapor deposition process;

[0064] 8) Reducing reflection and improving passivation, depositing a silicon nitride antireflection film with one or more layers of structure on the front side of the cell, and completing it through the PECVD chemical vapor deposition process;

[0065] 9) According to the grid line pattern on the back of the battery cell, laser grooves are made on the back of the battery cell, and laser processing is performed at the corresponding position to obtain positioning marking point 7;

[0066] 10) As shown in the instruction manual Figure 6 As shown, a CCD camera is used to capture the positioning Marking point 7, and a printing screen is used to accurately align the positioning Marking point 7 with the back silver grid line 3;

[0067] 11) As attached to the instruction manual Figure 7 As shown, two CCD cameras are used to capture the positioning Marking point 7 after one printing, and the back aluminum grid line 4 is accurately aligned with the positioning Marking point 7 through the two printing screens, and the back aluminum grid line 4 and the back silver grid line 3 are ensured to be printed and connected to each other;

[0068] 12) Print the front grid line 1 on the front of the battery and perform a sintering test.

[0069] A PERC bifacial cell assembly packaging process, used for PERC bifacial cells, comprises the following steps:

[0070] 1) As attached to the instruction manual Figure 9 and attached Figure 11 As shown, one end of the metal welding wire 5 is used to align and interconnect with the back silver grid line 3 of the battery, and the other end of the metal welding wire 5 is interconnected with the front grid line 1 of another battery;

[0071] 2) Connect the positive and negative electrodes of the battery cells in sequence to form a battery string, and lay out and stack the battery strings;

[0072] 3) Laminate the stacked battery strings and perform frame testing on the laminated parts to complete the component packaging.

[0073] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A PERC double-sided battery, comprising a plurality of front grid lines (1) disposed on the front side of the battery and a plurality of back grid lines (2) disposed on the back side of the battery, characterized in that: A plurality of the back grid lines (2) are horizontally spaced apart, and the back grid lines (2) are formed by alternately connecting a plurality of back silver grid lines (3) and a plurality of back aluminum grid lines (4) to form the back structure of the PERC double-sided battery; a printing overlap area (6) is provided at the connection of the back silver grid lines (3) and the back aluminum grid lines (4); the adjacent upper and lower back silver grid lines (3) are connected by a metal wire (5); the back silver grid lines (3) in the up and down directions are on the same vertical line for welding connection by the metal wire (5).

2. The PERC double-sided battery according to claim 1, characterized in that: Both ends of the back grid line (2) are provided with back aluminum grid lines (4).

3. A PERC double-sided battery according to claim 1, characterized in that: Both ends of the back grid line (2) are provided with back silver grid lines (3).

4. A PERC double-sided battery according to claim 1, characterized in that: One end of the back grid line (2) is provided with a back silver grid line (3), and the other end is provided with a back aluminum grid line (4).

5. A PERC double-sided battery according to claim 4, characterized in that: On one side of a plurality of the back grid lines (2), back silver grid lines (3) are arranged from top to bottom.

6. A PERC double-sided battery according to claim 4, characterized in that: On one side of a plurality of the back grid lines (2), back silver grid lines (3) and back aluminum grid lines (4) are arranged at intervals from top to bottom.

7. A method for manufacturing the PERC double-sided battery according to any one of claims 1 to 6, comprising the following steps: 1) Using a single or multi-crystalline silicon wafer to obtain a good textured surface structure through surface texturing; 2) Cleaning the liquid remaining during texturing; 3) Reacting phosphorus oxychloride with the silicon wafer to obtain phosphorus atoms. After a certain time, the phosphorus atoms enter the surface layer of the silicon wafer and penetrate and diffuse into the silicon wafer through the gaps between silicon atoms to form an interface between an N-type semiconductor and a P-type semiconductor; 4) Removing the edge PN junction through plasma etching to avoid short circuit at the edge; 5) Since the diffusion junction formation process will form a layer of phosphosilicate glass on the surface of the silicon wafer, reducing the impact on the efficiency of the solar cell through the phosphosilicate glass removal process; 6) Depositing a passivation layer of aluminum oxide with a certain thickness on the back of the battery by the ALD or PERC method; 7) Depositing a silicon nitride antireflection film with one or more layers of structure on the back, and completing the preparation of the antireflection film through the PECVD chemical vapor deposition process; 8) Depositing a silicon nitride antireflection film with one or more layers of structure on the front of the battery, and completing it through the PECVD chemical vapor deposition process; It is characterized in that it further includes: 9) Laser grooving the back of the battery and performing laser treatment at corresponding positions to obtain positioning Marking points (7); 10) Using a first CCD camera to capture the positioning Marking points (7), and accurately aligning and printing the back silver grid lines (3) through a first printing screen with the positioning Marking points (7); 11) Using a second CCD camera to capture the positioning Marking points (7) after the first printing, and accurately aligning and printing the back aluminum grid lines (4) through a second printing screen with the positioning Marking points (7), and ensuring that the back aluminum grid lines (4) and the back silver grid lines (3) are alternately connected to each other; 12) Printing the front grid lines (1) on the front of the battery and performing sintering tests.

8. A PERC double-sided cell module encapsulation process, for the PERC double-sided cell described in any one of claims 1 to 6, characterized in that, Comprising the following steps: 1) Align and interconnect one end of the metal bonding wire (5) with the back silver grid line (3) of the battery, and interconnect the other end of the metal bonding wire (5) with the front grid line (1) of another battery; 2) Connect the batteries in series according to the positive and negative poles of the battery cells in sequence, and perform layout and lamination on the battery string; 3) Laminate the laminated battery string, and perform framing and testing on the laminated component to complete the production of module encapsulation.

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