Main-grid-free back contact cell string and photovoltaic module

Abstract

The utility model discloses a main-grid-free back contact battery string and a photovoltaic assembly, the main-grid-free back contact battery string comprises a plurality of back contact battery pieces arranged along a first direction, and the back surface of each back contact battery piece is provided with first fine grids and second fine grids which are alternately arranged along the first direction; the first welding strips and the second welding strips are alternately arranged in the second direction; wherein for the same back contact battery piece, the first welding strip is electrically connected with the first fine grid, and is insulated from the second fine grid; the second welding strip is insulated from the first fine grid and is electrically connected with the second fine grid; welding layers are arranged at the contact positions of the first fine grid and the first welding strip and the contact positions of the second fine grid and the second welding strip; the welding layer comprises a welding metal layer and a bonding glue layer, and the bonding glue layer covers the welding metal layer. According to the utility model, the welding quality of the welding strip can be improved, and the connection stability and reliability of the welding strip and the fine grid are ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to solar cell technical field especially relates to a kind of no main grid back contact cell string and photovoltaic module. BACKGROUND

[0002] No main grid back contact cell piece adopts solder strip to replace the main grid of solar cell, can greatly reduce the usage amount of cell silver pulp, reduce the shading of grid line, increase the light receiving area of cell piece, reduce cost while improving the photoelectric conversion efficiency of cell piece.Solder strip is connected into cell string while replacing main grid to gather current on the fine grid of cell piece, so it is necessary to guarantee the welding quality and connection stability between solder strip and cell piece, and in order to avoid short circuit problem, when solder strip is connected with cell piece, it is necessary to print insulating paste on the heterogeneous grid line of cell piece, and no main grid cell piece welding point is fine and dense, and welding requirement is high, which can easily cause the welding quality between solder strip and fine grid to decrease, and affect the long-term reliability of module. SUMMARY

[0003] The utility model solves the technical problems that provide a kind of no main grid back contact cell string, can improve the welding quality of solder strip, guarantee the connection stability and reliability of solder strip and fine grid.

[0004] The utility model further solves the technical problems that provide a kind of photovoltaic module, and photoelectric conversion efficiency is high.

[0005] In order to solve the above problems, the utility model discloses a kind of no main grid back contact cell string, including the back contact cell piece of being arranged along first direction by several, the back surface of the back contact cell piece has the first fine grid and second fine grid of being alternately arranged along first direction, the polarity of the first fine grid and second fine grid is opposite;

[0006] First solder strip and second solder strip, the first solder strip and second solder strip are alternately arranged along second direction;The first solder strip and second solder strip are connected with two back contact cell piece of adjacent arrangement respectively;

[0007] Wherein, for the same back contact cell piece, the first solder strip is electrically connected with the first fine grid, and is insulated with second fine grid;The second solder strip is insulated with the first fine grid, and is electrically connected with second fine grid;The position where the first fine grid and first solder strip, second fine grid and second solder strip contact is equipped with welding layer, and the first solder strip and second solder strip are electrically contacted with the welding layer respectively;

[0008] The welding layer includes welding metal layer and adhesive layer, and the adhesive layer covers the welding metal layer.

[0009] As an improvement of the above technical solution, the adhesive layer covers the position where the first solder strip contacts the first and second fine grids and the position where the second solder strip contacts the first and second fine grids.

[0010] As an improvement of the above technical solution, the first solder strip contacts the solder metal layer on the first fine grid, and the second solder strip contacts the solder metal layer on the second fine grid.

[0011] As an improvement of the above technical solution, an insulating layer is arranged at the position where the first fine grid and the second solder strip contact, and at the position where the second fine grid and the first solder strip contact, and the first solder strip and the second solder strip respectively contact the insulating layer.

[0012] As an improvement of the above technical solution, the height of the solder metal layer is D, the height of the insulating layer is d, and the D and d satisfy the following relationship: 0.6*d≤D≤1.5*d.

[0013] As an improvement of the above technical solution, the d is 10μm-80μm, and the D is 10μm-80μm.

[0014] As an improvement of the above technical solution, the width of the solder metal layer is less than or equal to the width of the first solder strip and / or the second solder strip.

[0015] As an improvement of the above technical solution, along the second direction, the width of the adhesive layer is greater than the width of the first solder strip and / or the second solder strip.

[0016] As an improvement of the above technical solution, the material of the solder metal layer is one or more of conductive silver paste, silver-coated copper paste, tin-coated copper paste, and tin paste.

[0017] As an improvement of the above technical solution, along the third direction, the cross-sectional shape of the first solder strip and the second solder strip is one of circular, triangular, rectangular, and trapezoidal.

[0018] As an improvement of the above technical solution, the first solder strip is electrically connected to the first fine grid on one of the back contact battery pieces through the solder layer, and is electrically connected to the second fine grid on another of the back contact battery pieces through the solder layer, and the second solder strip is electrically connected to the second fine grid on one of the back contact battery pieces through the solder layer, and is electrically connected to the first fine grid on another of the back contact battery pieces through the solder layer.

[0019] As the improvement of the above technical scheme, the first solder strip is insulated from a second fine grid on one of the back contact cell pieces through the insulating layer and is insulated from a first fine grid on another of the back contact cell pieces through the insulating layer, and the second solder strip is insulated from the first fine grid on one of the back contact cell pieces through the insulating layer and is insulated from the second fine grid on another of the back contact cell pieces through the insulating layer.

[0020] Correspondingly, the utility model discloses a photovoltaic module, including above-mentioned no main grid back contact cell string.

[0021] Implement the utility model, there is following beneficial effect:

[0022] The utility model discloses a welding metal layer and bonding adhesive layer are positioned to the solder strip and are bonded, improve the welding tensile force of solder strip, and the welding metal layer increases the conductivity of solder strip and fine grid, and the bonding adhesive layer covers the welding metal layer, and the bonding adhesive layer can provide the bonding force of each direction to solder strip, and the welding tensile force of solder strip is assisted to improve, guarantees the welding stability of solder strip. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is the cross section structure schematic drawing of one back contact cell piece in no main grid back contact cell string provided by the utility model embodiment 1;

[0024] Figure 2 It is the back structure schematic drawing of one back contact cell piece in no main grid back contact cell string provided by the utility model embodiment 1;

[0025] Figure 3 It is the back structure schematic drawing of one back contact cell piece in no main grid back contact cell string provided by the utility model embodiment 4;

[0026] Figure 4 It is the back structure schematic drawing of one back contact cell piece in no main grid back contact cell string provided by the utility model embodiment 5;

[0027] Figure 5 It is Figure 1 The A part enlarged view of. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the utility model clearer and more apparent, the following in combination with the drawings and examples, the utility model is further described in detail. The examples of the examples are shown in the drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The examples described below by reference to the drawings are exemplary and are used only to explain the utility model and cannot be understood as limiting the utility model. In addition, it should be understood that the specific examples described herein are only used to explain the utility model and do not limit the utility model.

[0029] In the description of the utility model, it should be understood that the terms "upper", "lower", "back surface", "front surface" and the like indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as limiting the utility model.

[0030] In the utility model, "preferred" is only for the implementation mode or embodiment with better effect, and it should be understood that it does not constitute a limitation on the protection scope of the utility model.

[0031] In the utility model, the technical features described in an open manner include a closed technical scheme consisting of the listed features, and also include an open technical scheme including the listed features.

[0032] Referring to Figure 1 and Figure 2 The utility model provides a kind of main gridless back contact cell string, including the back contact cell piece 1 of being arranged along first direction by several, the back surface of the back contact cell piece 1 has first fine grid 11 and second fine grid 12 alternately arranged along first direction, the polarity of first fine grid 11 and second fine grid 12 is opposite;

[0033] First solder strip 21 and second solder strip 22, first solder strip 21 and second solder strip 22 are alternately arranged along second direction;First solder strip 21 and second solder strip 22 are connected with two back contact cell pieces 1 arranged adjacently respectively;

[0034] Among them, for the same back contact cell piece 1, first solder strip 21 is electrically connected with first fine grid 11, and is insulated with second fine grid 12;Second solder strip 22 is insulated with first fine grid 11, and is electrically connected with second fine grid 12;First fine grid 11 and first solder strip 21, second fine grid 12 and second solder strip 22 are provided with welding layer 3 at the position of contact, and first solder strip 21 and second solder strip 22 are electrically connected with welding layer 3 respectively;

[0035] The welding layer 3 comprises a welding metal layer 31 and an adhesive layer 32 covering the welding metal layer 31.

[0036] In the prior art, the welding strip is insulated from one kind of fine grid in the back contact battery piece by the insulating glue, and the welding strip and the fine grid of another polarity are conductively connected after pressure welding, the pulling force between the welding strip and the back contact battery piece is relatively weak, and the welding strip and the back contact battery piece can be loose. In addition, insufficient welding tension can also cause the power of the assembly to decrease and other phenomena, ultimately affecting the overall performance of the assembly. The welding metal layer and the adhesive layer are used for positioning and bonding the welding strip in the utility model, the welding tension of the welding strip is assisted to be improved, the welding metal layer increases the conductive performance of the welding strip and the fine grid, the adhesive layer covers the welding metal layer, the adhesive layer flows under the extrusion of the welding strip during the welding process, the adhesive layer can provide adhesive force in all directions to the welding strip, the welding tension of the welding strip is assisted to be improved, and the welding stability of the welding strip is ensured.

[0037] In order to avoid the welding strip from contacting two kinds of grid lines of different polarities at the same time, causing the positive and negative poles of the same back contact battery piece to be connected, and causing the back contact battery piece to be short-circuited, the positions where the first fine grid 11 and the second welding strip 22 and the second fine grid 12 and the first welding strip 21 contact are provided with an insulating layer 4, and the first welding strip 21 and the second welding strip 22 respectively contact the insulating layer 4.

[0038] The specific structure of the back contact battery string without a main grid provided by the utility model is as follows:

[0039] In the back contact battery string without a main grid, a plurality of back contact battery pieces 1 are arranged along a first direction. It can be understood that the two adjacent back contact battery pieces 1 can be arranged at intervals, abutted or arranged with the edge portions overlapping, and the specific arrangement mode is selected according to the actual situation.

[0040] In the back contact battery string without a main grid, the first welding strip 21 and the second welding strip 22 are placed on the two adjacent back contact battery pieces 1, the first welding strip 21 and the second welding strip 22 are alternately arranged along a second direction, along the first direction, one end of the first welding strip 21 is in contact with the first fine grid 11 of one back contact battery piece 1 through the welding layer 3 and is in contact with the second fine grid 12 of the back contact battery piece 1 through the insulating layer 4; the other end of the first welding strip 21 is in contact with the second fine grid 12 of the other back contact battery piece 1 adjacent to the first welding strip 21 through the welding layer 3 and is in contact with the first fine grid 11 of the back contact battery piece 1 through the insulating layer 4.

[0041] Correspondingly, along the first direction, one end of the second solder strip 22 contacts the second fine grid 12 of one back contact battery piece 1 through the solder layer 3, and contacts the first fine grid 11 of the back contact battery piece 1 through the insulating layer 4; the other end of the second solder strip 22 contacts the first fine grid 11 of another adjacent back contact battery piece 1 through the solder layer 3, and contacts the second fine grid 12 of the back contact battery piece 1 through the insulating layer 4.

[0042] Specifically, the material of the solder metal layer 31 can be one or more of conductive silver paste, silver-coated copper paste, tin-coated copper paste, and tin paste. Preferably, the material of the solder metal layer is tin paste, and the composition of the tin paste is at least one of tin-lead, tin-lead-bismuth, tin-bismuth, or tin-bismuth-silver. The adhesive layer 32 can be an insulating adhesive layer or a conductive adhesive layer. In order to avoid the short circuit caused by the contact between the solder strip and the grid line in the non-electrically connected area through the adhesive layer, the adhesive layer 4 is preferably an insulating adhesive layer.

[0043] The first direction intersects the second direction. In an embodiment, the first direction can be the longitudinal direction of the back contact battery piece 1, and the second direction can be the transverse direction of the back contact battery piece 1, and the two directions are perpendicular to each other.

[0044] As shown in Figure 2 In an embodiment, the adhesive layer 32 only covers the solder metal layer 31, that is, the solder metal layer 31 and the adhesive layer 32 are both discontinuously arranged, each solder metal layer 31 and adhesive layer 32 covers one grid line, which can well position the adhesive and improve the soldering tension of the solder strip. Figure 3 As shown in

[0045] As shown in Figure 4 In a preferred embodiment, the adhesive layer 32 covers the positions where the first solder strip 21 contacts the first fine grid 11 and the second fine grid 12, and the positions where the second solder strip 22 contacts the first fine grid 11 and the second fine grid 12, that is, the solder metal layer 31 is discontinuously arranged, and the adhesive layer 32 is continuously arranged. Compared with the adhesive layer 32 covering only one fine grid, the adhesive layer 32 covering multiple fine grids at the same time can provide greater adhesion to the entire solder strip.

[0046] The prior art realizes the insulation of the solder strip and the heterogeneous grid line through the insulating glue. After pressure welding, the height of the solder strip in contact with the insulating glue is higher than the height of the solder strip in other areas, thereby affecting the flatness of the solder strip. It can be understood that, during pressure welding, the adhesive layer and the glue film flow under the influence of pressure. The upper limit of the height of the adhesive layer is different for different welding methods. Therefore, further, in order to make the solder strip more flat and improve the welding quality, the height of the welding metal layer 31 and the insulating layer 4 and the relationship therebetween are optimized. Specifically, as shown in Figure 5 after pressure welding, the height of the welding metal layer 31 is D, the height of the insulating layer 4 is d, and the D and d satisfy the following relationship: 0.6*d≤D≤1.5*d. If D<0.6*d, the connection reliability of the solder strip and the grid line in the electrical connection area is poor; if D>1.5*d, the insulation effect of the solder strip and the heterogeneous grid line at the insulating layer is affected.

[0047] In a preferred embodiment, the d is 10μm-80μm, and is exemplarily 20μm, 30μm, 40μm, 50μm or 70μm, but is not limited thereto. If the height of the insulating layer is too small, the basic insulation performance cannot be guaranteed; if the thickness of the insulating layer is too large, the overall height difference of the solder strip is increased, which is not conducive to performance improvement. The D is 10μm-80μm, and is exemplarily 20μm, 30μm, 40μm, 50μm or 70μm, but is not limited thereto. If the thickness of the welding layer is too small, uneven distribution will cause poor welding points; if the thickness of the welding layer is too large, the production cost is increased, and welding quality problems such as excessive welding points are caused.

[0048] It can be understood that, in order to save the amount of welding metal, in a preferred embodiment, the width of the welding metal layer 31 is less than or equal to the width of the first solder strip 21 and / or the second solder strip 22. The solder strip completely covers the welding metal layer 31, which is conducive to improving the welding stability. In the area where each solder strip contacts the grid line, the welding metal layer 31 can be a plurality of welding metal blocks, and the shape of the welding metal block can be rectangular or circular. Preferably, the welding metal block is rectangular.

[0049] In order to better improve the tensile force of the adhesive layer on the solder strip, the width of the adhesive layer 32 is greater than the width of the first solder strip 21 and / or the second solder strip 22. The adhesive layer wraps the solder strip and provides adhesive force in multiple directions of the solder strip, which is conducive to improving the welding tensile force. In a preferred embodiment, as shown in Figure 3 each solder strip contacts the grid line, the adhesive layer can be arranged in sections, which saves cost, and the shape of the adhesive layer can be rectangular or circular. Preferably, the adhesive layer can be rectangular and consistent with the extension direction of the solder strip, and the adhesive force is more uniform. In a preferred embodiment, as shown in Figure 4As shown, the bonding adhesive layer 32 can be continuously arranged along the extension direction of the solder strip in the area where each solder strip contacts the grid line, and the shape of the bonding adhesive layer can be rectangular or circular. Preferably, the bonding adhesive layer is rectangular, and the length can be greater than or equal to the length of the contact area of the solder strip and the back contact battery piece in the first direction.

[0050] In the third direction, the cross-sectional shape of the first solder strip 21 and the second solder strip 22 is one of circular, triangular, rectangular, and trapezoidal, wherein the third direction is the thickness direction of the battery piece. Preferably, the cross-sectional shape of the first solder strip 21 and the second solder strip 22 is circular. The circular solder strip can more uniformly and fully extrude the bonding adhesive layer to both sides under stress conditions, thereby wrapping the solder strip and fully contacting the solder metal layer to achieve more sufficient welding and ensure the welding effect.

[0051] Correspondingly, the utility model also provides a preparation method of the main grid-free back contact battery string, which comprises the following steps:

[0052] S100, providing a plurality of back contact battery pieces; the back surface of the back contact battery piece is provided with a first fine grid and a second fine grid, and the first fine grid and the second fine grid are arranged alternately in sequence;

[0053] S200, preparing a solder layer at the position where the first fine grid and the first solder strip and the second fine grid and the second solder strip contact;

[0054] Specifically, the preparation of the solder layer comprises:

[0055] Preparation of a solder metal layer at the position where the first fine grid and the first solder strip and the second fine grid and the second solder strip contact, and coating of a bonding adhesive on the solder metal layer to form a bonding adhesive layer covering the solder metal layer.

[0056] In the preparation process, the solder paste can be printed at the corresponding position, and after printing, the solder paste can be heated and cured through an oven or a curing furnace, or without heating and curing. In a preferred embodiment, when the solder paste is not heated and cured, the connection performance of the solder strip and the solder paste in the subsequent welding process is ensured.

[0057] S300, preparing an insulating layer at the position where the first fine grid and the second solder strip and the second fine grid and the first solder strip contact;

[0058] In the preparation process, the insulating adhesive can be printed at the corresponding position, and after printing, the insulating adhesive can be heated and cured through an oven or a curing furnace to form an insulating layer. It can be understood that in the utility model, the order of S200 and S300 is not limited, and S200 can be performed first, or S300 can be performed first, or both can be performed simultaneously. The specific implementation is not limited herein.

[0059] S400, laying a first solder strip and a second solder strip, so that the first solder strip is in contact with the solder layer on the first fine grid, and the insulating layer on the second fine grid, and the second solder strip is in contact with the solder layer on the second fine grid, and the insulating layer on the first fine grid; in a preferred embodiment, pressure welding is performed to make the first solder strip electrically conductive with the first solder layer, and the second solder strip electrically conductive with the second solder layer.

[0060] Further, the utility model provides a kind of no main grid battery module, including first cover plate, first adhesive film, at least one above-mentioned no main grid back contact battery string, second adhesive film and second cover plate are sequentially stacked.

[0061] Specifically, wherein the first cover plate is generally made of high light transmittance, strong weatherability material, including but not limited to glass, polycarbonate, first cover plate can protect the sensitive elements inside battery module from the invasion of external environment, while providing necessary mechanical support, ensure the structural integrity of battery module.

[0062] The first adhesive film is located between the first cover plate and the no main grid back contact battery string, and mainly plays a role of bonding and sealing, to ensure that the battery module does not have problems such as delamination or water leakage during long-term use. The material of the first adhesive film includes but is not limited to EVA, POE, EPE and PVB. EVA adhesive film is low in price and high in light transmittance. POE adhesive film has good water vapor barrier effect and PID resistance. EPE adhesive film combines the advantages of EVA adhesive film and POE adhesive film, which is beneficial to sealing the assembly and improving the quality of the assembly, and can also reduce the cost. PVB adhesive film has higher penetration resistance, meeting the performance requirements of glass curtain wall interlayer safety glass.

[0063] The no main grid battery string is the no main grid back contact battery string described above or prepared according to the method described above.

[0064] The second adhesive film is located between the no main grid back contact battery string and the second cover plate, and has a similar effect to the first adhesive film, which is beneficial to sealing the assembly and improving the quality of the assembly.

[0065] The second cover plate is usually made of a material with strong weather resistance, including but not limited to aluminum plate and back plate film. The main function of the second cover plate is to protect the back of the battery module from the influence of the external environment and provide additional mechanical support, and it can also serve as an insulating layer of the battery module to ensure safety in use.

[0066] The second cover plate, the first adhesive film, the second adhesive film, the insulating layer and the adhesive layer can be designed in the same color system, such as white, black, transparent color, etc., to achieve the consistency effect of the appearance of the assembly.

[0067] Correspondingly, the utility model provides a kind of preparation method of no main grid battery module, comprising the following steps:

[0068] S1, first adhesive film is laid on the first cover plate;

[0069] S2, several no main grid back contact cell strings are laid on the first adhesive film;

[0070] S3, second adhesive film is laid on the back of the no main grid back contact cell string;

[0071] S4, second cover plate is laid on the second adhesive film;

[0072] S5, laminating treatment is carried out, and the photovoltaic module laminated piece is obtained.

[0073] The no main grid back contact cell string includes the no main grid back contact cell string described above or / and the no main grid back contact cell string prepared according to the above method.

[0074] The utility model is further described below with specific embodiments:

[0075] Embodiment 1

[0076] The embodiment provides a kind of no main grid back contact cell string, including back contact cell piece, back contact cell piece has the first fine grid and second fine grid of alternate arrangement along first direction on back, the polarity of first fine grid and second fine grid is opposite;

[0077] First solder strip and second solder strip, first solder strip and second solder strip are alternately arranged along second direction;First solder strip and second solder strip are connected respectively to two back contact cell pieces of adjacent arrangement;

[0078] Wherein, the position of first fine grid and first solder strip contact is equipped with welding layer, and first solder strip and first welding layer are electrically contacted;The position of second fine grid and second solder strip contact is equipped with welding layer, and second solder strip and welding layer are electrically contacted;Welding layer includes welding metal layer and adhesive layer, and adhesive layer covers welding metal layer.

[0079] The position of first fine grid and second solder strip contact is equipped with insulating layer, and second solder strip is insulated and isolated with first fine grid through insulating layer, and the position of second fine grid and first solder strip contact is equipped with insulating layer, and first solder strip is insulated and isolated with second fine grid through insulating layer.

[0080] The height of welding metal layer is D, and the height of insulating layer is d, which is 48 μm and 80 μm respectively.

[0081] Embodiment 2

[0082] The embodiment provides a main-grid-free back contact cell string, which comprises a back contact cell piece, the back surface of the back contact cell piece is provided with first fine grids and second fine grids which are arranged alternately along a first direction, and the polarities of the first fine grids and the second fine grids are opposite;

[0083] The first solder strip and the second solder strip are arranged alternately along a second direction; the first solder strip and the second solder strip are connected with two back contact cell pieces arranged adjacently respectively.

[0084] The position of the first fine grid, which is in contact with the first solder strip, is provided with a solder layer, and the first solder strip is in electrical contact with the first solder layer; the position of the second fine grid, which is in contact with the second solder strip, is provided with a solder layer, and the second solder strip is in electrical contact with the solder layer; the solder layer comprises a solder metal layer and a bonding glue layer, and the bonding glue layer covers the solder metal layer.

[0085] The position of the first fine grid, which is in contact with the second solder strip, is provided with an insulating layer, the second solder strip is insulated and separated from the first fine grid through the insulating layer, the position of the second fine grid, which is in contact with the first solder strip, is provided with an insulating layer, and the first solder strip is insulated and separated from the second fine grid through the insulating layer.

[0086] The height of the solder metal layer is D, and D is 75 microns; the height of the insulating layer is d, and d is 50 microns.

[0087] Embodiment 3

[0088] The embodiment provides a main-grid-free back contact cell string, which comprises a back contact cell piece, the back surface of the back contact cell piece is provided with first fine grids and second fine grids which are arranged alternately along a first direction, and the polarities of the first fine grids and the second fine grids are opposite;

[0089] The first solder strip and the second solder strip are arranged alternately along a second direction; the first solder strip and the second solder strip are connected with two back contact cell pieces arranged adjacently respectively.

[0090] The position of the first fine grid, which is in contact with the first solder strip, is provided with a solder layer, and the first solder strip is in electrical contact with the first solder layer; the position of the second fine grid, which is in contact with the second solder strip, is provided with a solder layer, and the second solder strip is in electrical contact with the solder layer; the solder layer comprises a solder metal layer and a bonding glue layer, and the bonding glue layer covers the solder metal layer.

[0091] The position of the first fine grid, which is in contact with the second solder strip, is provided with an insulating layer, the second solder strip is insulated and separated from the first fine grid through the insulating layer, the position of the second fine grid, which is in contact with the first solder strip, is provided with an insulating layer, and the first solder strip is insulated and separated from the second fine grid through the insulating layer.

[0092] The height of the solder metal layer is D, and D is 40 microns; the height of the insulating layer is d, and d is 50 microns.

[0093] Embodiment 4

[0094] The embodiment provides a main-grid-free back contact cell string, which comprises back contact cell pieces, the back surface of the back contact cell pieces is provided with first fine grids and second fine grids which are arranged alternately along a first direction, and the polarities of the first fine grids and the second fine grids are opposite;

[0095] The first solder strips and the second solder strips are arranged alternately along a second direction, and the first solder strips and the second solder strips are connected with two back contact cell pieces arranged adjacently respectively.

[0096] The position, at which the first fine grid contacts the first solder strip, is provided with a soldering layer, and the first solder strip is in electrical contact with the first soldering layer; the position, at which the second fine grid contacts the second solder strip, is provided with a soldering layer, and the second solder strip is in electrical contact with the soldering layer; the soldering layer comprises a soldering metal layer and a bonding glue layer, and the bonding glue layer is discontinuously arranged at the position, at which the first solder strip contacts the first fine grid and the second fine grid, and at the position, at which the second solder strip contacts the first fine grid and the second fine grid.

[0097] The position, at which the first fine grid contacts the second solder strip, is provided with an insulating layer, and the second solder strip is insulated from the first fine grid through the insulating layer; the position, at which the second fine grid contacts the first solder strip, is provided with an insulating layer, and the first solder strip is insulated from the second fine grid through the insulating layer.

[0098] The height of the soldering metal layer is D, and the height of the insulating layer is d, both of which are 50 microns.

[0099] Embodiment 5

[0100] The embodiment provides a main-grid-free back contact cell string, which comprises back contact cell pieces, the back surface of the back contact cell pieces is provided with first fine grids and second fine grids which are arranged alternately along a first direction, and the polarities of the first fine grids and the second fine grids are opposite;

[0101] The first solder strips and the second solder strips are arranged alternately along a second direction, and the first solder strips and the second solder strips are connected with two back contact cell pieces arranged adjacently respectively.

[0102] The position, at which the first fine grid contacts the first solder strip, is provided with a soldering layer, and the first solder strip is in electrical contact with the first soldering layer; the position, at which the second fine grid contacts the second solder strip, is provided with a soldering layer, and the second solder strip is in electrical contact with the soldering layer; the soldering layer comprises a soldering metal layer and a bonding glue layer, and the bonding glue layer is discontinuously arranged at the position, at which the first solder strip contacts the first fine grid and the second fine grid, and at the position, at which the second solder strip contacts the first fine grid and the second fine grid.

[0103] The position, at which the first fine grid contacts the second solder strip, is provided with an insulating layer, and the second solder strip is insulated from the first fine grid through the insulating layer; the position, at which the second fine grid contacts the first solder strip, is provided with an insulating layer, and the first solder strip is insulated from the second fine grid through the insulating layer.

[0104] The height of the welding metal layer is D, which is 50 μm, and the height of the insulation layer is d, which is 50 μm.

[0105] The welding metal layer and the adhesive layer are used for positioning and bonding the welding strip, the welding tensile force of the welding strip is improved, the adhesive layer can provide bonding force in each direction for the welding strip, the welding tensile force of the welding strip is improved, and the welding stability of the welding strip is ensured.

[0106] The above is the preferred embodiment of the utility model, and it should be pointed out that, for ordinary skilled persons in the art, without departing from the principle of the utility model, a number of improvements and refinements can be made, and these improvements and refinements are also considered to be within the protection scope of the utility model.

Claims

1. A back contact cell string without a main grid, characterized in that, The back contact cell string comprises a plurality of back contact cells arranged along a first direction, the back surface of the back contact cell has a first fine grid and a second fine grid arranged alternately along the first direction, the polarity of the first fine grid and the second fine grid is opposite; The first solder strip and the second solder strip are arranged alternately along a second direction; the first solder strip and the second solder strip are connected to two adjacent back contact cells respectively; For the same back contact cell, the first solder strip is electrically connected to the first fine grid and is insulated from the second fine grid; the second solder strip is insulated from the first fine grid and is electrically connected to the second fine grid; the position where the first fine grid and the first solder strip, the second fine grid and the second solder strip are in contact is provided with a solder layer, the first solder strip is in electrical contact with the solder layer on the first fine grid, and the second solder strip is in electrical contact with the solder layer on the second fine grid; The solder layer comprises a solder metal layer and an adhesive layer, and the adhesive layer covers the solder metal layer.

2. The gridless back contact cell string of claim 1, wherein, The adhesive layer covers the position where the first solder strip and the first fine grid and the second fine grid are in contact, and the position where the second solder strip and the first fine grid and the second fine grid are in contact.

3. The gridless back contact cell string of claim 1, wherein, The first solder strip is in contact with the solder metal layer on the first fine grid, and the second solder strip is in contact with the solder metal layer on the second fine grid.

4. The gridless back contact cell string of claim 1, wherein, The position where the first fine grid and the second solder strip, the second fine grid and the first solder strip are in contact is provided with an insulating layer, and the first solder strip and the second solder strip are in contact with the insulating layer respectively.

5. The gridless back contact cell string of claim 4, wherein, The height of the solder metal layer is D, and the height of the insulating layer is d, and the D and d satisfy the following relationship: 0.6*d≤D≤1.5*d.

6. The gridless back contact cell string of claim 5, wherein, The d is 10μm-80μm, and the D is 10μm-80μm.

7. The gridless back contact cell string of claim 1, wherein, Along the second direction, the width of the solder metal layer is less than or equal to the width of the first solder strip and / or the second solder strip.

8. The gridless back contact cell string of claim 1, wherein, Along the second direction, the width of the adhesive layer is greater than the width of the first solder strip and / or the second solder strip.

9. The gridless back contact cell string of claim 1, wherein, Along a third direction, the cross-sectional shape of the first solder strip and the second solder strip is one of a circle, a triangle, a rectangle, and a trapezoid.

10. The gridless back contact cell string of claim 4, wherein, The first solder strip is electrically connected to the first fine grid on one back contact cell through the solder layer and is electrically connected to the second fine grid on another back contact cell through the solder layer, and the second solder strip is electrically connected to the second fine grid on one back contact cell through the solder layer and is electrically connected to the first fine grid on another back contact cell through the solder layer.

11. The gridless back-contact cell string of claim 10, wherein, The first solder strip is insulated from the second fine grid on one back contact cell through the insulating layer and is insulated from the first fine grid on another back contact cell through the insulating layer, and the second solder strip is insulated from the first fine grid on one back contact cell through the insulating layer and is insulated from the second fine grid on another back contact cell through the insulating layer.

12. A photovoltaic module, characterized by The back contact cell string comprises a plurality of back contact cells arranged along a first direction, the back surface of the back contact cell has a first fine grid and a second fine grid arranged alternately along the first direction, the polarity of the first fine grid and the second fine grid is opposite;

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