Series connection method of back contact battery pieces

Abstract

A series connection method of back contact battery pieces belongs to the field of solar battery preparation, and is characterized by comprising the following steps: printing UV glue on the surfaces of the back contact battery pieces; conductive wires are arranged on the surfaces of the battery pieces needing to be connected in series; an ultraviolet lamp is turned on for irradiation, so that the UV glue is cured, and a back contact cell string is prepared; laying an adhesive film protection layer on the surface of the battery string; laminating the battery strings, and pressing the conductive wires on the surfaces of the battery pieces; and the conductive wires are in ohmic contact with a to-be-conducted area on the surface of the battery piece. The narrow conductive wires are adopted, the double-sided rate of the module is high, the generating capacity of the module can be effectively improved, and the LCOE of the system is reduced; the UV glue is used for fixing the conductive wires, so that the problem that the conductive wires deviate on the surfaces of the battery pieces in the lamination process and the long-term use process of the assembly can be avoided, and the short-circuit risk of the conductive wires is reduced; crimping or welding is achieved in the laminating process, battery string bending caused by high-temperature welding is avoided, and meanwhile the pseudo soldering problem is avoided.

Description

Technical Field

[0001] The invention belongs to the field of solar cell preparation, and in particular relates to a series connection method of back contact solar cells. Background Art

[0002] Unlike traditional solar cells, the front of the back-contact solar cell is not blocked by a metal electrode, so it can receive sunlight to the greatest extent and improve the utilization rate of light.

[0003] This structural design reduces the reflection and shadow loss of light from the front electrode, allowing more sunlight to be absorbed by the battery and converted into electrical energy. Although back-contact battery technology has many advantages, it still faces some challenges in practical applications. Among them, the most important problem is how to achieve the series connection of back-contact battery cells to ensure the overall performance of the battery assembly.

[0004] The traditional back-contact battery series connection method mainly adopts a high-temperature welding solution with a wide solder strip, which often has the following problems: (1) The traditional back-contact battery welding solution mostly adopts a wider solder strip with a low double-sided rate; (2) The solder strip is easily offset during lamination and long-term use, posing a risk of short circuit; (3) The solder paste used in the welding process will dissolve the silver grid line when heated, causing the risk of over-welding. In addition, high-temperature welding can easily cause the battery cell to bend and damage the battery structure. Summary of the invention

[0005] The present invention aims to solve the above problems and provides a method for series connection of back-contact solar cells.

[0006] The method for connecting back-contact solar cells in series according to the present invention comprises the following steps: Print UV glue on the surface of the back contact cell; The conductive wire is arranged on the surface of the battery cells to be connected in series; Turn on the ultraviolet light to cure the UV glue, fix the conductive wire and the battery sheet, and obtain a back contact battery string; Laying a protective layer of adhesive film on the surface of the battery string to prevent the conductive wire from being wrapped by the packaging material during the lamination process; The battery string is laminated, and the conductive wire is pressed against the surface of the battery cell; the conductive wire and the area on the surface of the battery cell that needs to be conducted are in ohmic contact.

[0007] Furthermore, in the series connection method of the back-contacted solar cells of the present invention, the conductive wire is arranged perpendicularly to the fine grid on the back-contacted solar cells; 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; by using a narrower conductive wire, the shielding of incident light on the back side of the back contact cell can be reduced, so that more sunlight can irradiate the effective power generation area on the back side of the cell, thereby increasing the bifaciality of the back contact cell.

[0008] Furthermore, in the method for connecting back-contact cells in series of the present invention, the UV adhesive is arranged in the area where the cell surface contacts the conductive wire but does not need to achieve ohmic contact; the area that does not need to achieve ohmic contact is: in the conductive wire coverage area, the area between the intersection of the fine grid surface and the conductive wire to achieve ohmic contact. Generally, in applications, there are two types of fine grids on the surface of the cell: one is that the fine grid is continuous and uninterrupted, and the UV adhesive is above the insulating adhesive at the intersection of the conductive wire and the fine grid; the other is that the fine grid is intermittent, and the UV adhesive is located in the area where the conductive wire and the intermittent part of the fine grid intersect.

[0009] Furthermore, in the method for connecting back-contacted cells in series of the present invention, the conductive wire is disconnected in the area where ohmic contact is not required between the cell surface and the conductive wire by using a fine grid or by pre-arranging insulating glue on the cell surface; When the fine grid is disconnected, the aforementioned UV glue is arranged at the fine grid disconnection; insulation is achieved by the fine grid disconnection, the insulating glue is omitted, the disconnection length can be reduced, and the current collection efficiency can be improved; When the insulating glue is pre-arranged on the surface, the UV glue is arranged above the insulating glue.

[0010] Furthermore, in the method for connecting back-contact battery cells in series of the present invention, solder paste is pre-arranged in the area where the battery cell surface and the conductive wire need to achieve ohmic contact; the use of insulating glue will raise the height of the conductive wire, so solder paste needs to be arranged in the area where conduction is required to maintain the height of the conductive wire.

[0011] Furthermore, in the series connection method of back-contact battery cells of the present invention, the melting point of the solder paste is lower than the lamination temperature, which can effectively enhance the contact effect.

[0012] The method for connecting back-contact battery cells in series of the present invention adopts UV glue pre-fixation and crimping technology to replace traditional solder welding to achieve connection between batteries. This technology has the following advantages: (1) The present invention adopts narrower conductive wires, and the double-sided rate of the component is high, which can effectively increase the power generation of the component and reduce the system levelized cost of electricity (LCOE); (2) The conductive wire is fixed by UV glue, which can avoid the problem of the conductive wire being offset on the surface of the battery cell during the lamination process and the long-term use of the component, thereby reducing the risk of short circuit of the conductive wire; (3) Crimping or welding is achieved during the lamination process to avoid bending of the battery string caused by high-temperature welding, and at the same time avoid the occurrence of cold soldering problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the back contact cell structure according to the first embodiment of the present invention; Figure 2 This is a schematic diagram of the process of the series connection method of back-contact solar cells according to the first embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of pre-arranging solder paste on the back contact solar cell according to the second embodiment of the present invention; Figure 4 This is a schematic flow chart of a method for connecting back-contact solar cells in series according to the second embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of pre-arranging solder paste on the back contact solar cell according to the third embodiment of the present invention; Figure 6 This is a schematic diagram of the process of the series connection method of back-contact solar cells according to the third embodiment of the present invention; Among them, 1-battery cell, 2-conductive wire, 3-UV glue, 4-fine grid, 5-solder paste, 6-insulating glue. DETAILED DESCRIPTION

[0014] The method for connecting back-contact solar cells in series according to the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0015] Embodiment 1 This embodiment discloses a method for connecting back-contact solar cells in series. Figure 2 As shown, the specific steps include: Step S1: Printing UV glue 3 on the surface of the back contact cell 1; In this embodiment, the UV glue 3 is arranged in the area where the battery cell 1 contacts the conductive wire 2 but does not need to achieve ohmic contact; the area that does not need to achieve ohmic contact is: in the area covered by the conductive wire 2, the area between the intersection points where the fine grid 4 surface and the conductive wire 2 achieve ohmic contact; like Figure 1 As shown, in the embodiment of the present disclosure, 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 disconnecting the fine grid 4; the UV glue 3 is arranged at the disconnection of the fine grid 4; insulation is achieved by disconnecting the fine grid 4, the insulating glue 6 is omitted, the disconnection length can be reduced, and the current collection efficiency can be improved.

[0016] Step S2: placing the conductive wire 2 on the surface of the battery cell 1 to be connected in series; like Figure 1 As shown, in the embodiment of the present disclosure, the laying direction of the conductive wire 2 is perpendicular to the fine grid 4 and cross-laid; the cross-sectional shape of the conductive wire 2 is a rectangle with a width less than 0.6 mm.

[0017] Step S3: Turn on the ultraviolet lamp to cure the UV glue 3, fix the conductive wire 2 and the battery cell 1, and obtain a back contact battery string.

[0018] Step S4: Laying a low-fluidity adhesive film protective layer on the surface of the battery string to prevent the conductive wire 2 from being wrapped by the packaging material during the lamination process; Step S5: laminating the battery string and its auxiliary materials, the conductive wire 2 is pressed tightly against the surface of the battery cell 1, the conductive wire 2 is directly overlapped with the fine grid 4 line, and ohmic contact is achieved with the area on the surface of the battery cell 1 that needs to be turned on.

[0019] Embodiment 2 Based on the above-mentioned embodiment 1, this embodiment discloses a method for connecting back-contact solar cells in series. In this embodiment, the difference from embodiment 1 is that solder paste 5 is pre-arranged in the area where ohmic contact is required on the surface of the solar cell 1; Figure 4 The specific steps shown are as follows: Step S1: applying solder paste 5 on 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.

[0020] Step S2: Printing UV glue 3 on the surface of the back contact cell 1; In this embodiment, the UV glue 3 is arranged in the area where the battery cell 1 contacts the conductive wire 2 but does not need to achieve ohmic contact; the area that does not need to achieve ohmic contact is: in the area covered by the conductive wire 2, the area between the intersection points where the fine grid 4 surface and the conductive wire 2 achieve ohmic contact; like Figure 3 As shown, in the embodiment of the present disclosure, 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 disconnecting the fine grid 4; the UV glue 3 is arranged at the disconnection of the fine grid 4; insulation is achieved by disconnecting the fine grid 4, the insulating glue 6 is omitted, the disconnection length can be reduced, and the current collection efficiency can be improved.

[0021] Step S3: placing the conductive wire 2 on the surface of the battery cell 1 to be connected in series; like Figure 3 As shown, in the embodiment of the present disclosure, the laying direction of the conductive wire 2 is perpendicular to the fine grid 4 and cross-laid; the cross-sectional shape of the conductive wire 2 is a circle with a diameter less than 0.2 mm.

[0022] Step S4: Turn on the ultraviolet lamp to cure the UV glue 3, fix the conductive wire 2 and the battery cell 1, and obtain a back contact battery string.

[0023] Step S5: Laying a low-fluidity adhesive film protective layer on the surface of the battery string to prevent the conductive wire 2 from being wrapped by the packaging material during the lamination process.

[0024] Step S6: The battery string and its auxiliary materials are laminated, and the conductive wire 2 is pressed tightly against the surface of the battery cell 1 and realizes ohmic contact with the area on the surface of the battery cell 1 that needs to be conducted.

[0025] Embodiment 3 This embodiment discloses a method for connecting back-contact solar cells in series. Figure 6 As shown, the specific steps include: Step S1: printing insulating glue 6 on the surface of the back contact cell 1 and heating and curing; In the embodiment of the present disclosure, in the area covered by the conductive wire 2, an insulating glue 6 is arranged to insulate the conductive wire 2 from the area on the surface of the battery cell 1 where ohmic contact is not allowed; Step S2: disposing solder paste 5 on the surface of the back contact cell 1; pre-arranging solder paste 5 in 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.

[0026] Step S3: Printing UV glue 3 on the surface of the back contact cell 1; In the embodiment of the present disclosure, the UV glue 3 is arranged in the area where the battery cell 1 contacts the conductive wire 2 but does not need to achieve ohmic contact; the area that does not need to achieve ohmic contact is: in the area covered by the conductive wire 2, the area between the surface of the fine grid 4 and the intersection point where the conductive wire 2 achieves ohmic contact; by reducing the size of the UV glue 3, the fine grid 4 is penetrated to improve the current collection efficiency; Step S4: placing the conductive wire 2 on the surface of the battery cell 1 to be connected in series; The cross-sectional shape of the conductive wire 2 is a rectangle with a width less than 0.3 mm.

[0027] Step S5: Turn on the ultraviolet lamp to cure the UV glue 3, fix the conductive wire 2 and the battery cell 1, and obtain a back contact battery string.

[0028] In this embodiment, the conductive wire 2 is fixed on the battery cell 1 by UV glue 3; Figure 5 As shown, the UV glue 3 is arranged above the insulating glue 6; the laying direction of the conductive wire 2 is perpendicular to the fine grid 4 and cross-laid; Step S6: Laying a low-fluidity adhesive film protective layer on the surface of the battery string to prevent the conductive wire 2 from being wrapped by the packaging material during the lamination process; Step S7: The battery string and its auxiliary materials are laminated, and the conductive wire 2 is pressed tightly against the surface of the battery cell 1 and realizes ohmic contact with the area on the surface of the battery cell 1 that needs to be conducted.

Claims

1. A method for connecting back-contact solar cells in series, characterized in that The following steps are involved: Print UV glue on the surface of the back contact cell; The conductive wire is arranged on the surface of the battery cells to be connected in series; Turning on the ultraviolet lamp to cure the UV glue to obtain a back contact battery string; Laying a protective film layer on the surface of the battery string; The battery string is laminated, and the conductive wire is pressed against the surface of the battery cell; the conductive wire and the area on the surface of the battery cell that needs to be conducted are in ohmic contact.

2. The method for connecting back-contact solar cells in series according to claim 1, characterized in that: The conductive wire is arranged perpendicularly to the fine grid on the back contact cell sheet; 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.

3. The method for connecting back-contact solar cells in series according to claim 2, characterized in that: The UV glue is disposed on the surface of the cell in an area that contacts the conductive wire but does not need to achieve ohmic contact; The area where ohmic contact is not required is the area between the surface of the fine grid and the intersection of the conductive wires that achieve ohmic contact in the conductive wire coverage area.

4. The method for connecting back-contact solar cells in series according to claim 1 or 3, characterized in that: The area where the conductive wire does not need to achieve ohmic contact with the surface of the battery cell is achieved by disconnecting the conductive wire with a fine grid or pre-arranging insulating glue on the surface of the battery cell; When the fine grid is disconnected, the aforementioned UV glue is arranged at the fine grid disconnection; When the insulating glue is pre-arranged on the surface, the UV glue is arranged above the insulating glue.

5. The method for connecting back-contact solar cells in series according to claim 4, characterized in that: Solder paste is pre-arranged in the area where the surface of the battery cell and the conductive wire need to achieve ohmic contact.

6. The method for connecting back-contact solar cells in series according to claim 5, characterized in that: The melting point of the solder paste is lower than the lamination temperature.

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