Series connection method for back contact cells

Abstract

A series connection method of back contact cell belongs to the field of solar cell preparation, and is characterized in that: UV glue is printed on the surface of the back contact cell; a conductive wire is arranged on the surface of the cell to be connected in series; a UV lamp is turned on to irradiate, so that the UV glue is cured to obtain a back contact cell string; a glue film protective layer is laid on the surface of the cell string; the cell string is laminated, and the conductive wire is compressed on the surface of the cell; and the conductive wire realizes ohmic contact with the conductive area on the surface of the cell. The narrower conductive wire is adopted, the high module double-sided rate is realized, the power generation of the module can be effectively improved, and the system LCOE is reduced; the UV glue is used to fix the conductive wire, the problem of deviation of the conductive wire on the surface of the cell caused in the laminating process and the long-term use of the module can be avoided, the short circuit risk of the conductive wire is reduced; the crimping or welding is realized in the laminating process, the bending of the cell string caused by high-temperature welding is avoided, and the false welding problem is avoided.

Description

Technical Field

[0001] This invention belongs to the field of solar cell manufacturing, and particularly relates to a method for connecting back-contact solar cells in series. Background Technology

[0002] Unlike traditional solar cells, back-contact solar cells do not have metal electrodes blocking their front side, thus maximizing the absorption of sunlight and improving light utilization.

[0003] This structural design reduces light reflection and shading loss at the front electrode, allowing more sunlight to be absorbed and converted into electrical energy. Despite the numerous advantages of back-contact battery technology, several challenges remain in practical applications. The most significant challenge is achieving series connection of the back-contact cells to ensure the overall performance of the battery module.

[0004] Traditional back-contact battery series connection method mainly adopts high-temperature welding scheme with wide solder strip, which often has the following problems: (1) Traditional back-contact battery welding scheme often uses a wide solder strip, resulting in low double-sided ratio; (2) During lamination and long-term use, the solder strip is prone to shift, which poses a short circuit risk; (3) The solder paste used in the welding process will melt the silver grid line when heated, causing over-welding risk. In addition, high-temperature welding can easily cause the battery cell to bend, damaging the battery structure. Summary of the Invention

[0005] The present invention aims to solve the above problems and provides a method for connecting back-contact battery cells in series.

[0006] The method for connecting back-contact battery cells in series according to the present invention includes the following steps:

[0007] UV adhesive is printed on the surface of the back contact cell.

[0008] The conductive wire is placed on the surface of the battery cells that need to be connected in series;

[0009] Turn on the ultraviolet lamp to cure the aforementioned UV adhesive, thereby fixing the conductive wire and the battery cell to obtain a back contact battery string.

[0010] A protective film layer is laid on the surface of the battery string to prevent the conductive wires from being wrapped by the encapsulation material during the lamination process.

[0011] The battery string is laminated, and the conductive wire is pressed tightly onto the surface of the battery cell; the conductive wire and the area on the surface of the battery cell that needs to be conductive are made into ohmic contact.

[0012] Furthermore, in the series connection method of the back contact battery cells of the present invention, the conductive wire is arranged perpendicularly to the fine grid on the back contact battery cell;

[0013] The cross-section of the conductive wire is rectangular or circular;

[0014] The width of the rectangle is less than 0.8 mm; the diameter of the circle is less than 0.4 mm; by using a narrower conductive wire, the obstruction of incident light on the back of the back contact battery can be reduced, allowing more sunlight to illuminate the effective power generation area on the back of the battery, thereby increasing the bifaciality of the back contact battery.

[0015] Furthermore, in the series connection method for back-contact solar cells described in this invention, the UV adhesive is applied to the area on the surface of the solar cell that is in contact with the conductive wire but does not require ohmic contact. The area where ohmic contact is not required is the region between the intersection points of the fine grid surface and the conductive wire within the conductive wire coverage area, where ohmic contact is achieved. Generally, in applications, there are two types of fine grids on the surface of the solar cell: one is a continuous, uninterrupted grid, in which case the UV adhesive is applied above the insulating adhesive at the intersection of the conductive wire and the fine grid; the other is an intermittent grid, in which case the UV adhesive is located in the area where the conductive wire and the fine grid intersect.

[0016] Furthermore, in the series connection method of the back contact battery cells described in this invention, the area where the conductive wire does not need to achieve ohmic contact with the surface of the battery cell is achieved by means of fine grid disconnection or pre-arranging insulating adhesive on the surface of the battery cell.

[0017] When the fine grid is used for disconnection, the aforementioned UV adhesive is applied at the fine grid disconnection point; insulation is achieved by the fine grid disconnection, eliminating the need for insulating adhesive, reducing the disconnection length, and improving current collection efficiency;

[0018] When the surface is pre-applied with insulating adhesive, the aforementioned UV adhesive is placed on top of the insulating adhesive.

[0019] Furthermore, in the series connection method of the back contact battery cells described in this invention, solder paste is pre-applied to the area on the surface of the battery cell where ohmic contact with the conductive wire is required; the use of insulating adhesive will increase the height of the conductive wire, so solder paste needs to be applied in the area where conductivity is required to maintain the height of the conductive wire.

[0020] Furthermore, in the series connection method of the back contact battery cells described in this invention, the melting point of the solder paste is lower than the lamination temperature, which can effectively enhance the contact effect.

[0021] The back-contact cell series connection method of the present invention uses UV glue pre-fixation and crimping technology to replace traditional brazing solder to realize the connection between cells. This technology has the following advantages: (1) The present invention uses narrower conductive wires, the module has a high bifaciality, which can effectively improve the power generation of the module and reduce the levelized cost of electricity (LCOE); (2) Using UV glue to fix the conductive wires can avoid the problem of the conductive wires shifting on the surface of the cell during the lamination process and during the long-term use of the module, and reduce the risk of short circuit of the conductive wires; (3) Crimping or welding is realized during the lamination process to avoid the bending of the cell string caused by high temperature welding, and at the same time avoid the occurrence of poor welding problems. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the back contact battery cell structure described in Embodiment 1 of the present invention;

[0023] Figure 2 This is a schematic diagram of the series connection method for back contact battery cells according to Embodiment 1 of the present invention;

[0024] Figure 3 This is a schematic diagram of the structure for pre-arranging solder paste on the back contact battery cell according to Embodiment 2 of the present invention;

[0025] Figure 4 This is a schematic diagram of the series connection method for back contact battery cells according to Embodiment 2 of the present invention;

[0026] Figure 5 This is a schematic diagram of the structure for pre-arranging solder paste on the back contact battery cell according to Embodiment 3 of the present invention;

[0027] Figure 6 This is a schematic diagram of the series connection method for back contact battery cells according to Embodiment 3 of the present invention;

[0028] Among them, 1-battery cell, 2-conductive wire, 3-UV adhesive, 4-fine grid, 5-solder paste, and 6-insulating adhesive. Detailed Implementation

[0029] The following detailed description of the series connection method for back contact battery cells according to the present invention is provided with reference to the accompanying drawings and embodiments.

[0030] Example 1

[0031] This embodiment discloses a method for connecting back-contact battery cells in series, such as... Figure 2 As shown, the specific steps include the following:

[0032] Step S1: Print UV adhesive 3 on the surface of the back contact cell 1;

[0033] In this embodiment, the UV adhesive 3 is placed in the area where the battery cell 1 contacts the conductive wire 2 but does not need to achieve ohmic contact; the area where ohmic contact is not needed is the area between the surface of the fine grid 4 and the intersection point where ohmic contact is achieved between the conductive wire 2 and the area covered by the conductive wire 2.

[0034] like Figure 1 As shown in this embodiment, in the area covered by the conductive wire 2, the conductive wire 2 is insulated from the area on the surface of the battery cell 1 where ohmic contact is not allowed by using a fine grid 4 to disconnect the area; the UV adhesive 3 is arranged at the disconnection of the fine grid 4; insulation is achieved by disconnecting the fine grid 4, eliminating the need for insulating adhesive 6, reducing the length of the disconnection, and improving the current collection efficiency.

[0035] Step S2: Place the conductive wire 2 on the surface of the battery cell 1 that needs to be connected in series;

[0036] like Figure 1 As shown, in this embodiment of the present disclosure, the conductive wire 2 is laid in a direction that is perpendicular to and intersects with the fine grid 4; the cross-sectional shape of the conductive wire 2 is a rectangle with a width of less than 0.6 mm.

[0037] Step S3: Turn on the ultraviolet lamp to cure the UV adhesive 3, thereby fixing the conductive wire 2 and the battery cell 1, and obtaining the back contact battery string.

[0038] Step S4: Lay a low-flow adhesive film protective layer on the surface of the battery string to prevent the conductive wires 2 from being wrapped by the encapsulation material during the lamination process;

[0039] Step S5: The battery string and its auxiliary materials are laminated, and the conductive wire 2 is pressed tightly onto the surface of the battery cell 1. The conductive wire 2 is directly connected to the fine grid 4 line and achieves ohmic contact with the area on the surface of the battery cell 1 that needs to be conductive.

[0040] Example 2

[0041] Based on the aforementioned Embodiment 1, this embodiment discloses a method for connecting back-contact battery cells in series. The difference between this embodiment and Embodiment 1 is that solder paste 5 is pre-applied to the area on the surface of the battery cell 1 where ohmic contact is required; for example... Figure 4 The specific steps shown are as follows:

[0042] Step S1: Apply solder paste 5 to the surface of the back contact cell 1; in this embodiment, the melting point of the solder paste 5 is lower than the lamination temperature to enhance the contact effect.

[0043] Step S2: Print UV adhesive 3 on the surface of the back contact cell 1;

[0044] In this embodiment, the UV adhesive 3 is placed in the area where the battery cell 1 contacts the conductive wire 2 but does not need to achieve ohmic contact; the area where ohmic contact is not needed is the area between the surface of the fine grid 4 and the intersection point where ohmic contact is achieved between the conductive wire 2 and the area covered by the conductive wire 2.

[0045] like Figure 3 As shown in this embodiment, in the area covered by the conductive wire 2, the conductive wire 2 is insulated from the area on the surface of the battery cell 1 where ohmic contact is not allowed by using a fine grid 4 to disconnect the area; the UV adhesive 3 is arranged at the disconnection of the fine grid 4; insulation is achieved by disconnecting the fine grid 4, eliminating the need for insulating adhesive 6, reducing the length of the disconnection, and improving the current collection efficiency.

[0046] Step S3: Place the conductive wire 2 on the surface of the battery cell 1 that needs to be connected in series;

[0047] like Figure 3 As shown in the embodiment of this disclosure, the conductive wire 2 is laid in a direction that is perpendicular to and intersects with the fine grid 4; the cross-sectional shape of the conductive wire 2 is a circle with a diameter of less than 0.2 mm.

[0048] Step S4: Turn on the ultraviolet lamp to cure the UV adhesive 3, thereby fixing the conductive wire 2 and the battery cell 1, and obtaining the back contact battery string.

[0049] Step S5: Lay a low-flow adhesive film protective layer on the surface of the battery string to prevent the conductive wires 2 from being wrapped by the encapsulation material during the lamination process.

[0050] Step S6: The battery string and its auxiliary materials are laminated, and the conductive wire 2 is pressed tightly onto the surface of the battery cell 1 and makes ohmic contact with the area on the surface of the battery cell 1 that needs to be conductive.

[0051] Example 3

[0052] This embodiment discloses a method for connecting back-contact battery cells in series, such as... Figure 6 As shown, the specific steps include the following:

[0053] Step S1: Print insulating adhesive 6 on the surface of the back contact cell 1 and heat to cure;

[0054] In this embodiment of the disclosure, an insulating adhesive 6 is arranged in the area covered by the conductive wire 2 to insulate the conductive wire 2 from the area on the surface of the battery cell 1 where ohmic contact is not allowed.

[0055] Step S2: Apply solder paste 5 to the surface of the back contact cell 1; solder paste 5 is pre-applied to the area on the surface of the cell 1 where ohmic contact is required; the melting point of the solder paste 5 is lower than the lamination temperature to enhance the contact effect.

[0056] Step S3: Print UV adhesive 3 on the surface of the back contact cell 1;

[0057] In this embodiment, the UV adhesive 3 is positioned in the area where the battery cell 1 contacts the conductive wire 2 but ohmic contact is not required; the area where ohmic contact is not required is the area between the surface of the fine grid 4 and the intersection point where ohmic contact is achieved between the conductive wire 2 and the conductive wire 2 within the area covered by the conductive wire 2; by reducing the size of the UV adhesive 3, the fine grid 4 can be penetrated, thereby improving the current collection efficiency.

[0058] Step S4: Place the conductive wire 2 on the surface of the battery cell 1 that needs to be connected in series;

[0059] The cross-sectional shape of the conductive wire 2 is a rectangle with a width of less than 0.3 mm.

[0060] Step S5: Turn on the ultraviolet lamp to cure the UV adhesive 3, thereby fixing the conductive wire 2 and the battery cell 1, and obtaining the back contact battery string.

[0061] In this embodiment, the conductive wire 2 is fixed to the battery cell 1 by UV adhesive 3; as Figure 5 As shown, the UV adhesive 3 is arranged above the insulating adhesive 6; the conductive wire 2 is laid in a direction that is perpendicular to and intersects with the fine grid 4;

[0062] Step S6: Lay a low-flow adhesive film protective layer on the surface of the battery string to prevent the conductive wires 2 from being wrapped by the encapsulation material during the lamination process;

[0063] Step S7: The battery string and its auxiliary materials are laminated, and the conductive wire 2 is pressed tightly onto the surface of the battery cell 1 and makes ohmic contact with the area on the surface of the battery cell 1 that needs to be conductive.

Claims

1. A method for connecting back-contact solar cells in series, characterized in that... Includes the following steps: UV adhesive is printed on the surface of the back contact cell. The conductive wires are pre-fixed to the surface of the cells to be connected in series using UV adhesive; The UV adhesive is applied to the area on the surface of the battery cell that is in contact with the conductive wires but does not require ohmic contact. The area where ohmic contact is not required is the area between the fine grid surface and the intersection point where ohmic contact is achieved between the conductive wire and the conductive wire within the conductive wire coverage area. The area where the conductive wire does not need to make ohmic contact with the surface of the battery cell is achieved by either breaking the grid with fine grids or pre-applying insulating adhesive to the surface of the battery cell. When the fine grid is used for disconnection, the aforementioned UV adhesive is applied at the fine grid disconnection point; When the surface is pre-applied with insulating adhesive, the aforementioned UV adhesive is placed on top of the insulating adhesive. Turn on the ultraviolet lamp to cure the aforementioned UV adhesive, and obtain the back contact battery string; A protective film layer is laid on the surface of the battery string; The battery string is laminated, and the conductive wire is pressed tightly onto the surface of the battery cell; the conductive wire and the area on the surface of the battery cell that needs to be conductive are made into ohmic contact.

2. The method for connecting back-contact battery cells in series according to claim 1, characterized in that: Solder paste is pre-applied to the areas on the surface of the battery cell where ohmic contact with the conductive wire is required.

3. The method for connecting back-contact battery cells in series according to claim 2, characterized in that: The melting point of the solder paste is lower than the lamination temperature.

4. The method for connecting back-contact battery cells in series according to claim 3, characterized in that: The conductive wire is arranged perpendicularly to the fine grid on the back contact cell; The cross-section of the conductive wire is rectangular or circular; The width of the rectangle is less than 0.8 mm; the diameter of the circle is less than 0.4 mm.

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