Photovoltaic module and method of manufacturing the same

Abstract

The application provides a photovoltaic module and a preparation method thereof, and relates to the technical field of photovoltaic technology. The photovoltaic module comprises a conductive back plate and a plurality of composite back contact cell pieces on the conductive back plate. The conductive back plate comprises a conductive layer and a back plate which are arranged in a stack. The composite back contact cell piece comprises a back contact cell piece and an insulating layer on the back light side of the back contact cell piece, and the insulating layer is adjacent to the conductive layer. The insulating layer does not exceed the back contact cell piece. The back contact cell piece comprises a cell body and a current collecting grid line on the back light side of the cell body. The insulating layer is provided with a through hole penetrating through the insulating layer at a position corresponding to part of the current collecting grid line. The length of the first side is L1, the length of the second side is L2, the length of the third side is L3, and the length of the fourth side is L4. L3:L1 is 96:100 to 1:1, and / or L4:L2 is 95:100 to 1:1. The photovoltaic module is more beautiful.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a photovoltaic module and its manufacturing method. Background Technology

[0002] Back-contact solar cells, due to their structure without grid lines on the light-facing side, can make full use of sunlight, resulting in higher efficiency.

[0003] However, individual back-contact solar cells have poor mechanical strength, are easily affected by the environment, and have very low output voltage, current and power. Therefore, multiple back-contact solar cells are usually encapsulated into photovoltaic modules for use.

[0004] In existing photovoltaic modules, conductive backsheets can be used for conductive interconnection. However, existing photovoltaic modules using conductive backsheet interconnection suffer from high alignment difficulty, narrow processing window, and poor electrical performance. Summary of the Invention

[0005] This invention provides a photovoltaic module and its manufacturing method, aiming to solve the problem of poor positioning effect in existing photovoltaic modules.

[0006] In a first aspect, the present invention provides a photovoltaic module, comprising: a conductive backsheet and a plurality of composite back-contact solar cells located on the conductive backsheet; the conductive backsheet comprises: a conductive layer and a backsheet stacked thereon;

[0007] The composite back-contact solar cell includes: a back-contact solar cell and an insulating layer located on the backlight side of the back-contact solar cell, the insulating layer and the conductive layer being adjacent; the insulating layer does not extend beyond the back-contact solar cell; the back-contact solar cell includes: a battery body, and current collector grid lines located on the backlight side of the battery body, the insulating layer having through holes at positions corresponding to a portion of the current collector grid lines, the through holes being filled with a conductor; the backlight surface of the battery body includes: an intersecting first side and a second side; the first surface of the insulating layer near the back-contact solar cell includes: an intersecting third side and a fourth side; the extension directions of the first side and the third side are both parallel to the extension directions of the current collector grid lines; the extension directions of the second side and the fourth side are parallel; the length of the first side is L1, the length of the second side is L2, the length of the third side is L3, and the length of the fourth side is L4.

[0008] Wherein, L3:L1 = 96:100 to 1:1, and / or, L4:L2 = 95:100 to 1:1. In the photovoltaic module of this application, the insulating layer is pre-assembled with each back contact cell. First, during the assembly process, since the through-holes in the insulating layer only need to correspond to the positions of the conductors on each interconnection part of a back contact cell, the number of through-holes and conductors is greatly reduced, thus reducing the alignment difficulty of each through-hole and each conductor, expanding the processing window of through-holes and conductors, and improving the yield. Second, due to the lower alignment difficulty, the alignment accuracy is higher, avoiding electrical performance loss and improving the electrical performance of the photovoltaic module. Third, due to the higher alignment accuracy, the size of the through-holes can be slightly smaller to still meet the alignment requirements. The smaller through-hole size not only ensures the adhesion performance of the insulating layer, but also reduces the amount of material to be removed to form through-holes in the insulating layer, that is, reduces the cost of waste, and thus reduces costs. The invention reduces the cost of photovoltaic modules. Furthermore, the smaller size of the through-holes maintains the good mechanical and adhesive properties of the insulation layer and reduces the risk of short circuits. Fourth, the insulation layer is pre-composite to each back contact cell, simplifying the process, avoiding complex multi-step processes, and reducing costs. Fifth, the pre-composite insulation layer also protects the back contact cells, preventing scratches on their surface during transport. No separate protective layer is needed on the back contact cells, reducing processes and costs. Sixth, in this application, the insulation layer does not extend beyond a single back contact cell; L3:L1 = 96:100 to 1:1, and / or L4:L2 = 95:100 to 1:1. The spacing between adjacent back contact cells does not expose the insulation layer, making the photovoltaic module more aesthetically pleasing.

[0009] In some possible embodiments, the area ratio of the first surface to the backlight surface is 96:100 to 1:1, further ensuring that the third side is located within the first side and the fourth side is located within the second side. On the one hand, from the perspective of process yield, the insulating layer is smaller, which can further reduce the risk of microcracks during the bonding process between the insulating layer and the back contact cell. This is because the back contact cell completely covers the insulating layer and is a certain distance from the edge of the back contact cell. When thermally bonding the back contact cell and the insulating layer, pressure needs to be applied to fix the back contact cell and the insulating layer, thus avoiding the concentration of pressure points at the edge of the back contact cell and preventing microcracks from forming. On the other hand, the spacing between adjacent back contact cells will not expose the insulating layer, making the photovoltaic module more aesthetically pleasing.

[0010] In some possible embodiments, in the composite back contact cell: the distance between the first side and the third side is D1, and the distance from the current collector grid line adjacent to the first side to the first side is D2;

[0011] 0.3×D2≤D1≤1.5×D2, and further, 0.3×D2≤D1≤1.0×D2.

[0012] Within the aforementioned range, the relationship between D1 and D2 not only reduces the risk of short circuits but also provides a wider processing window for fabrication and alignment, shorter carrier transport paths at the battery body edges, lower transmission losses, and a wider processing window for the interconnects. When D1 ≤ 1.0 × D2, the insulating layer can cover all current collector lines, further reducing the risk of short circuits.

[0013] In some possible embodiments, in the composite back contact cell: the distance between the second side and the fourth side is D3, and the distance from the end of the current collector grid line to the second side is D4;

[0014] 0.2×D4≤D3≤1.3×D4, and further, 0.3×D4≤D3≤1.0×D4.

[0015] Within the aforementioned range, the relationship between D3 and D4 not only reduces short-circuit risk but also provides a wider processing window for fabrication and alignment, shorter carrier transport paths at the battery body edges, lower transmission losses, and a wider processing window for the interconnects. When D3 ≤ 1.0 × D4, the insulating layer can cover all current collector lines, further reducing short-circuit risk.

[0016] In some possible embodiments, at the edge of the photovoltaic module: the conductive layer extends to the outside of the insulating layer; the distance between the edge of the conductive layer and the adjacent fourth side is D5; in the composite back contact cell: the distance from the end of the current collector grid line to the second side is D4;

[0017] 0.5×D4≤D5≤1.8×D4.

[0018] Within the aforementioned range, the relationship between D5 and D4 not only improves the electrical connection reliability between the back contact cell and the conductive layer and reduces material waste, but also results in a shorter transport path for charge carriers at the edge of the battery body, lower transmission loss, and a wider processing window for the interconnection section 213.

[0019] In some possible embodiments, the conductive layer is distributed in a finger-like structure, and adjacent finger-like structures are isolated by waste wire grooves; at the edge of the photovoltaic module: the distance between the head edge of the finger-like structure and the adjacent third side is D6; the distance between the head edge of the waste wire groove and the adjacent edge in the conductive layer is D7, 0.3≤D6 / D7≤0.8.

[0020] Within the aforementioned range, the relationship between D6 and D7 not only reduces the risk of short circuits but also provides a wider processing window for machining and alignment.

[0021] In some possible embodiments, the photovoltaic module further includes: a busbar, on which at least a portion of the composite back-contact cells are disposed; the extension direction of at least a portion of the busbar is parallel to the extension direction of the current collector grid lines; and in a direction perpendicular to the extension direction of the busbar: the dimension of the portion of the insulating layer located on the busbar covers at least 2 / 3 of the width of the busbar.

[0022] The composite back contact cell and the busbar have a larger overlap size, which avoids the problem of microcracks or even cell cracks caused by excessive stress concentration due to a smaller overlap size.

[0023] In some possible embodiments, the insulation layer is a single or multiple layers; each layer comprises, by mass ratio, at least 20% linear low-density polyethylene, at least 30% block copolymer polypropylene, and at least 5% compatible toughened ethylene octene copolymer. The insulation layer 22 of the above materials exhibits good adhesion, as well as certain temperature resistance and support properties.

[0024] In some possible embodiments, the insulating layer is a thermoplastic insulating layer or a cross-linked thermo / photocurable insulating layer.

[0025] Cross-linked thermo / photocurable insulation layers have lower costs, while thermoplastic insulation layers offer better adhesive properties, resulting in better encapsulation and reliability.

[0026] In some possible embodiments, the photovoltaic module further includes: a gap film located on the side of the conductive layer near the insulating layer and corresponding to the spacing between adjacent back contact cells; the gap film contains pigment and, by mass ratio, comprises: at least 20% linear low-density polyethylene, at least 30% block copolymer polypropylene, and at least 5% compatible toughened ethylene octene copolymer.

[0027] The main material of the gap film is the same as that of the aforementioned insulating layer. The gap film can be obtained by adding pigment to the scraps of the aforementioned insulating layer. The material has a high degree of reusability, which can save process steps and reduce costs.

[0028] In some possible embodiments, the gap film comprises, by weight percentage: 5% to 8% rutile titanium dioxide, or 6% to 12% perylene-based high-reflectivity black pigment; and / or,

[0029] The thickness of the gap film ranges from 25 μm to 100 μm.

[0030] In some possible embodiments, the back contact cell further includes: a plurality of interconnects disposed on the side of the current collector grid line away from the battery body;

[0031] The maximum dimension of the interconnect portion along the extension direction of the first side is D8, and the length of the through hole along the extension direction of the third side is D9; 1.1×D8≤D9≤3×D8; and / or,

[0032] The through hole extends along the extension direction of the fourth side. In the extension direction of the second side, the distance between the interconnecting portions of the two opposite ends is D10. Along the extension direction of the fourth side, the length of the through hole is D11; 1.05×D10≤D11≤1.12×D10.

[0033] In some possible embodiments, the length of the through hole is D9 along the extension direction of the third side; the conductive layer is distributed in a finger-like structure, and adjacent finger-like structures are isolated by waste wire grooves; the distance between adjacent waste wire grooves is D12 along the extension direction of the third side.

[0034] 0.05≤D9 / D12≤0.3.

[0035] An excessively large D9 via may cross the waste wire groove, posing a short-circuit risk. Conversely, an excessively small D9 via results in a smaller amount of conductor within the via, leading to poor electrical connection between the collector grid and the conductive layer. In this application, 0.05 ≤ D9 / D12 ≤ 0.3 reduces the short-circuit risk and improves the electrical connection between the collector grid and the conductive layer.

[0036] In some possible embodiments, 0.08≤D9 / D12≤0.25; where D12 is the minimum distance between adjacent waste wire grooves along the extension direction of the third side.

[0037] Along the extension direction of the third side, at the minimum distance between adjacent waste wire grooves, the problem of excessively large through holes crossing the waste wire grooves can also be avoided, which can further reduce the risk of short circuits.

[0038] In some possible embodiments, the battery body includes: a corner located at the intersection of the first side and the second side, wherein at least two corners of the battery body extend beyond the insulating layer; and / or,

[0039] The insulating layer includes an edge portion and an inner portion located inside the edge; the thickness of the edge portion is greater than the height of the inner portion.

[0040] The insulation layer is slightly thicker at the edges, which provides better adhesion and facilitates tight bonding with the back contact cell.

[0041] A second aspect of the present invention provides a method for preparing a photovoltaic module, comprising:

[0042] An insulating layer and a back contact cell are provided; the back contact cell includes: a battery body, and current collector grid lines located on the backlight side of the battery body; the insulating layer has through holes at positions corresponding to some of the current collector grid lines;

[0043] The insulating layer is laminated onto the back-light side of the back-contact battery cell to obtain a composite back-contact battery cell; the through-hole is filled with a conductor; the back-light surface of the battery body includes: an intersecting first side and a second side; the first surface of the insulating layer near the back-contact battery cell includes: an intersecting third side and a fourth side; the third side is located within the first side, and the fourth side is located within the second side; the extension directions of the first side and the third side are both parallel to the extension directions of the current collector grid lines; the extension directions of the second side and the fourth side are parallel; the length of the first side is L1, the side length of the second side is L2, the length of the third side is L3, and the side length of the fourth side is L4; wherein, L3:L1 = 96:100 to 1:1, and / or, L4:L2 = 95:100 to 1:1;

[0044] The composite back contact solar cell is electrically interconnected with a conductive backplate; the conductive backplate includes: a conductive layer and a backplate stacked together; the insulating layer and the conductive layer are adjacent to each other.

[0045] In some possible embodiments, the step of providing the insulating layer includes:

[0046] Multi-layer co-extrusion forms a complete insulating layer;

[0047] Multiple insulating layers are obtained by cutting the entire insulating layer using die-cutting or laser cutting methods.

[0048] The co-extrusion method for forming the entire insulating layer in this application is simple, has fewer steps, and is lower in cost. Die-cutting production is low-cost, and the resulting insulating layer has a more regular shape without affecting the thickness of the insulating layer at different locations.

[0049] In some possible embodiments, before laminating the insulating layer onto the back-light side of the back-contact solar cell, the method further includes: setting a conductor at positions corresponding to some of the current collector grid lines; setting the conductor first and then laminating reduces the amount of material used for the conductor, thus lowering costs. The conductor can be set using printing methods such as stencil printing or screen printing.

[0050] In some possible embodiments, after the insulating layer is laminated to the backlight side of the back contact cell, the method further includes: placing a conductor at the position corresponding to the current collector grid line inside the through hole.

[0051] First, the insulating layer and the back contact cell are combined, and then the conductor is installed. In this case, even if there is splashing of the conductor slurry during the installation of the conductor, the splashed part is located on the side of the insulating layer away from the battery, and will not cause a short circuit problem.

[0052] In some possible embodiments, the insulating layer is laminated onto the back-light side of the back-contact solar cell, including:

[0053] The insulating layer is aligned with the back-light side of the back-contact battery cell using a vacuum adsorption method; the adsorption positions include: each corner of the insulating layer, and at least four other positions; the distance between adjacent adsorption positions is less than or equal to 1 / 3 of L4;

[0054] The insulating layer is heat-bonded to the back-light side of the back contact cell; and / or the insulating layer is adhesively bonded to the back-light side of the back contact cell; the heat-bonding temperature is 100°C to 200°C; the adhesive used for adhesive bonding includes a low-temperature curing acrylic adhesive.

[0055] In some possible embodiments, electrically interconnecting the composite back contact cell with the conductive backsheet includes:

[0056] The composite back contact cell is electrically interconnected with the conductive backplate by heating and pressing; the heating and pressing temperature is 220°C to 260°C, and the pressing pressure is 10MPa to 50MPa.

[0057] The photovoltaic modules and their preparation methods described above have the same or similar beneficial effects, and will not be repeated here to avoid repetition. Attached Figure Description

[0058] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0059] Figure 1 A partial structural diagram of a photovoltaic module disassembled according to an embodiment of the present invention is shown;

[0060] Figure 2 A schematic diagram of the mating structure of a composite back contact battery cell and a conductor is shown in an embodiment of the present invention;

[0061] Figure 3 A schematic diagram of a composite back-contact battery cell according to an embodiment of the present invention is shown;

[0062] Figure 4 A bottom view of the back-contact battery cell in an embodiment of the present invention is shown.

[0063] Figure 5 This diagram illustrates a schematic of the interaction structure between a conductive layer and an insulating layer at the edge of a photovoltaic module in an embodiment of the present invention.

[0064] Figure 6 This illustrates the interaction between the busbar and the adjacent insulating layer of a photovoltaic module in an embodiment of the present invention;

[0065] Figure 7 This diagram illustrates a different combination structure of conductive and insulating layers at the edge of a photovoltaic module in an embodiment of the present invention.

[0066] Explanation of the attached drawing numbers:

[0067] 1-Conductive backplate, 11-Conductive layer, 111-Finger structure, 112-Waste wire groove, 12-Backplate, 13-Post-encapsulation film, 2-Composite back contact cell, 21-Back contact cell, 211-Battery body, 2111-First side, 2112-Second side, 212-Current collector grid, 213-Interconnection part, 22-Insulating layer, 221-Through hole, 222-Third side, 223-Fourth side, 25-Current collector grid group, 26-Second electrical connection part, 3-Front encapsulation film, 4-Glass, 5-Conductor, 6-Busband. Detailed Implementation

[0068] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0069] The main reasons for the high alignment difficulty, narrow processing window, and poor electrical performance of existing photovoltaic modules using conductive backsheets are as follows: In existing conductive backsheets, the through-holes in the insulating layer usually correspond to the positions of conductors on the interconnects of multiple (e.g., dozens or even hundreds) back contact cells in the photovoltaic module. However, due to the large number of back contact cells in the photovoltaic module, and the large number of interconnects in each back contact cell, the alignment of each through-hole with each conductor is difficult. The installation of at least some through-holes and at least some conductors is difficult, the processing window for at least some through-holes and at least some conductors is narrow, and the yield is low. In addition, misalignment will also lead to loss of electrical performance, so the electrical performance of existing photovoltaic modules is poor.

[0070] To address the aforementioned technical issues, in the photovoltaic module of this application, the insulating layer is pre-assembled with each back contact cell. Firstly, during the assembly process, since the through-holes in the insulating layer only need to correspond to the positions of the conductors on each interconnection portion of a single back contact cell, the number of through-holes and conductors is significantly reduced. This lowers the difficulty of aligning each through-hole with each conductor, expands the processing window for through-holes and conductors, and improves yield. Secondly, due to the reduced alignment difficulty, the alignment accuracy is higher, avoiding electrical performance loss and improving the electrical performance of the photovoltaic module. Thirdly, due to the higher alignment accuracy, the size of the through-holes can be slightly smaller while still meeting the alignment requirements. Smaller through-hole sizes not only ensure the adhesion performance of the insulating layer but also reduce the amount of material removed to form through-holes in the insulating layer, thus reducing waste costs and consequently lowering the cost of the photovoltaic module. Furthermore, smaller through-hole sizes maintain the good mechanical and adhesive properties of the insulating layer and reduce the risk of short circuits. Fourthly, the insulating layer is pre-assembled with each back contact cell. The process is simpler, avoiding complex multi-step processes and reducing costs. Fifth, the insulation layer is pre-composite to each back contact cell, and the insulation layer can also protect the back contact cells, preventing scratches on the surface of the back contact cells during transportation. There is no need to set a separate protective layer on the back contact cells, reducing processes and lowering costs. Sixth, in this application, the third side is located inside the first side, the fourth side is located inside the second side, L3:L1 = 96:100 to 1:1, and / or, L4:L2 = 95:100 to 1:1. The spacing between adjacent back contact cells will not expose the insulation layer, making the photovoltaic module more aesthetically pleasing. The smaller the ratio of L3:L1 and L4:L2, the smaller the size of the insulation layer, which can reduce the amount of insulation layer used and reduce the cost of the photovoltaic module. However, if the size of the insulation layer is too small, it may expose the heterogeneous current collector wires, which may cause a short circuit when the heterogeneous current collector wires connect to the conductive back sheet. The above ratio range is the result of comprehensively considering cost and short circuit risk. The photovoltaic module not only has a lower cost but also a lower short circuit risk. Furthermore, the ratios L3:L1 = 98.6:100 to 1:1 and L4:L2 = 97.4:100 to 1:1 are further specified. Even further, if the edge of the insulating layer is too close to or flush with the edge of the back contact cell, stress concentration at the edge of the back contact cell can easily lead to microcracks. Therefore, the ratios L3:L1 = 98.6:99.5 to 99:99.5 and L4:L2 = 98.5:99.5 to 99:99.5 are further specified.

[0071] This invention provides a photovoltaic module, including: a conductive backsheet 1 and a plurality of composite back-contact solar cells 2 located on the conductive backsheet 1; the conductive backsheet 1 includes: a conductive layer 11 and a backsheet 12 stacked together. The conductive layer 12 is formed of a conductive material, such as metal foil, and is not specifically limited thereto; for example, it could be copper foil. The backsheet 12 provides support for the other layers of the conductive backsheet, and its specific material is not limited; for example, it could be glass.

[0072] Reference Figures 1 to 3 The composite back contact solar cell 2 includes: a back contact solar cell 21 and an insulating layer 22 located on the backlight side of the back contact solar cell 21, wherein the insulating layer 22 and the conductive layer 11 are adjacent. (Refer to...) Figure 4 The back contact cell 21 includes a cell body 211 and current collector grid lines 212 located on the backlight side of the cell body 211. The current collector grid lines 212 are used to collect and conduct current or charge carriers. Through-holes 221 penetrating the insulating layer 22 are provided at positions corresponding to a portion of the current collector grid lines 212, and the through-holes 221 are filled with a conductor 5. The conductor 5 has good conductivity and can be solder paste, solder glue, conductive adhesive, etc. The composition of the conductor 5 can be selected from metals such as silver, copper, lead, bismuth, zinc, and nickel; the specific material of the conductor 5 is not limited. The portion of the current collector grid lines 212 located at the through-holes is electrically connected to the conductive layer 11 through the conductor 5 to conduct current. When the through-hole 221 is small, exposing only one type of collector grid line 212, the insulating layer 22 can provide insulation, and no insulating element is needed. When the through-hole 221 is large, exposing two types of collector grid lines 212, one type of collector grid line 212 within the through-hole 221 is electrically connected to the conductive layer 11 via the conductor 5 to conduct current. The other type of collector grid line 212 within the through-hole 221 is provided with an insulating element (not shown in the figure) and is insulated from the conductive layer 11 through the insulating element. That is, the other type of collector grid line 212 within the through-hole 221 is shielded by the insulating element, avoiding the risk of short circuit. Other areas of the back-contact cell 21 are in contact with the insulating layer 22 to avoid short circuits and power loss. The two types of collector grid lines 212 here refer to: the P-type collector grid line electrically connected to the P-type doped layer, and the N-type collector grid line electrically connected to the N-type doped layer. (Refer to...) Figure 1 The conductive backplate 1 may further include a post-encapsulation film 13 disposed between the conductive layer 11 and the backplate 12. The insulating component here has good insulating properties and may be an insulating adhesive, etc., with no limitation on its specific composition.

[0073] Specifically, the conductor 5 here can directly contact the collector grid line 212 to achieve electrical connection; in one possible embodiment, refer to Figure 4The back contact cell 21 also includes: a plurality of interconnecting portions 213 disposed on the side of the current collector grid line 212 away from the battery body 211, and a conductor 5 disposed on the interconnecting portion 213 away from the surface of the battery body, and the current collector grid line 212 is electrically connected to the conductor through the interconnecting portion 213.

[0074] Reference Figure 3 and Figure 4The backlight surface of the battery body 211 includes an intersecting first side 2111 and a second side 2112. The angle between the first side 2111 and the second side 2112 is not limited; for example, it can be 90° or close to 90°. The back contact battery sheet 21 can be a whole back contact battery sheet, a half back contact battery sheet, a three-part back contact battery sheet, a four-part back contact battery sheet, a five-part back contact battery sheet, a six-part back contact battery sheet, etc., and the specific number of parts is not limited. The specific dimensions of the backlight surface of the battery body 211 are also not limited. For example, when the back contact battery cell 21 can be a single, continuous back contact battery cell, the length of the first side can be 170mm to 260mm, and the length of the second side can also be 170mm to 260mm. For instance, in the form of second side × first side, the overall battery size can be 260×260mm, 250×250mm, 240×240mm, 230×230mm, 220×220mm, 210×210mm, 192×192mm, 182×182mm, 170×170mm, or 260×210mm. m, 260×192mm, 260×182mm, 250×210mm, 250×192mm, 250×182mm, 240×210mm, 240×192mm, 240×182mm, 230×210mm, 230× 192mm, 230×182mm, 220×210mm, 220×192mm, 220×182mm, 210×210mm, 210×192mm, 210×182mm, 192×182mm, 182×170mm. For example, when the back contact cell 21 can be a half-cell back contact cell, the length of the first side can be 170mm to 260mm, and the length of the second side can be 85mm to 130mm. For example, in the form of second side × first side, the size of the half-cell can be 130×260mm, 125×250mm, 120×240mm, 115×230mm, 110×220mm, 105×210mm, 96×192mm, 91×182mm, 85×170mm, 130×210mm, etc. m, 130×192mm, 130×182mm, 125×210mm, 125×192mm, 125×182mm, 120×210mm, 120×192mm, 120×182mm, 115×210mm, 115 ×192mm, 115×182mm, 110×210mm, 110×192mm, 110×182mm, 105×210mm, 105×192mm, 105×182mm, 96×182mm, 91×170mm.For example, when the back contact cell 21 can be a three-piece back contact cell, the length of the first side can be from 170mm to 260mm, and the length of the second side can be from 56.7mm to 86.7mm. For example, in the form of second side × first side, the dimensions of the three-piece cell can be 86.7×260mm, 83.3×250mm, 80×240mm, 76.7×230mm, 73.3×220mm, 70×210mm, 64×192mm, 60.7×182mm, 56.7×170mm, 86.7×210mm, etc. 0mm, 86.7×192mm, 86.7×182mm, 83.3×210mm, 83.3×192mm, 83.3×182mm, 80×210mm, 80×192mm, 80×182mm, 76.7×210mm, 76 .7×192mm, 76.7×182mm, 73.3×210mm, 73.3×192mm, 73.3×182mm, 70×210mm, 70×192mm, 70×182mm, 64×182mm, 60.7×170mm. For example, when the back contact cell 21 can be a four-piece back contact cell, the length of the first side can be 170mm to 260mm, and the length of the second side can be 42.5mm to 65mm. For example, in the form of second side × first side, the dimensions of the four-piece cell can be 65×260mm, 62.5×250mm, 60×240mm, 57.5×230mm, 55×220mm, 52.5×210mm, 48×192mm, 45.5×182mm, 42.5×170mm, 65×210mm, etc. mm, 65×192mm, 65×182mm, 62.5×210mm, 62.5×192mm, 62.5×182mm, 60×210mm, 60×192mm, 60×182mm, 57.5×210mm, 57.5× 192mm, 57.5×182mm, 55×210mm, 55×192mm, 55×182mm, 52.5×210mm, 52.5×192mm, 52.5×182mm, 48×182mm, 45.5×170mm.For example, when the back contact cell 21 can be a five-piece back contact cell, the length of the first side can be 170mm to 260mm, and the length of the second side can be 34mm to 52mm. For example, in the form of second side × first side, the size of the five-piece cell can be 52×260mm, 50×250mm, 48×240mm, 46×230mm, 44×220mm, 42×210mm, 38.4×192mm, 36.4×182mm, 34×170mm, 52 ×210mm, 52×192mm, 52×182mm, 50×210mm, 50×192mm, 50×182mm, 48×210mm, 48×192mm, 48×182mm, 46×210mm, 46×192mm, 46×182mm, 44×210mm, 44×192mm, 44×182mm, 42×210mm, 42×192mm, 42×182mm, 38.4×182mm, 36.4×170mm. For example, when the back contact cell 21 can be a six-piece back contact cell, the length of the first side can be from 170mm to 260mm, and the length of the second side can be from 28.3mm to 43.3mm. For example, in the form of second side × first side, the size of the six-piece cell can be 43.3×260mm, 41.7×250mm, 40×240mm, 38.3×230mm, 36.7×220mm, 35×210mm, 32×192mm, 30.3×182mm, 28.3×170mm, 43.3×260mm, etc. 0mm, 43.3×192mm, 43.3×182mm, 41.7×210mm, 41.7×192mm, 41.7×182mm, 40×210mm, 40×192mm, 40×182mm, 38.3×210mm, 38.3×192mm, 38.3×182mm, 36.7×210mm, 36.7×192mm, 36.7×182mm, 35×210mm, 35×192mm, 35×182mm, 32×182mm, 30.3×170mm. The first surface of the insulating layer 22 near the back contact cell includes: intersecting third side 222 and fourth side 223. If the third side 222 is located within the first side 2111 and the fourth side 223 is located within the second side 2112, then the area of ​​the insulating layer 22 is less than or equal to the area of ​​the back contact cell. When light parallel to the thickness direction of the photovoltaic module is shone on the insulating layer and the back contact cell, the projection of the insulating layer lies within the projection of the back contact cell, or in other words, the projection of the back contact cell completely covers the projection of the insulating layer. The angle between the third side 222 and the fourth side 223 is not limited; for example, it can be 90° or close to 90°.The extension directions of the first side 2111 and the third side 222 are both parallel to the extension direction of the collector grid line 212; the extension directions of the second side 2112 and the fourth side 223 are parallel. In this application, the extension direction of a structure refers to its overall extension direction, while its parts may be allowed to bend in other directions; the parallelism mentioned in this application refers to absolute parallelism and near-parallelism, for example, the included angle between the two is less than or equal to 10°. The length of the first side 2111 is L1, the side length of the second side 2112 is L2, the length of the third side 222 is L3, and the side length of the fourth side 223 is L4. Wherein, L3:L1 = 96:100 to 1:1, and / or, L4:L2 = 95:100 to 1:1. When L3:L1 = 1:1 and L4:L2 = 1:1, the area of ​​the first surface of the insulating layer 22 near the back contact cell 21 is equal to the area of ​​the back surface of the cell body 211. In other cases, the area of ​​the first surface of the insulating layer 22 near the back contact cell 21 is smaller than the area of ​​the back surface of the cell body 211. The spacing between adjacent back contact cells 21 will not expose the insulating layer 22, making the photovoltaic module more aesthetically pleasing.

[0075] For example, L3:L1 is 96:100, 96.5:100, 97:100, 97.2:100, 97.5:100, 97.9:100, 98:100, 98.2:100, 98.5:100, 98.6:100, 98.8:100, 98.9:100, 99:100, 99.2:100, 99.3:100, 99.5:100, 99.6:100, 99.8:100, 99.9:100, 1:1. For example, L4:L2 can be 95:100, 95.3:100, 95.5:100, 96:100, 96.3:100, 96.5:100, 96.8:100, 97:100, 97.2:100, 97.4:100, 97.5:100, 97.7:100, 97.9:100, 98:100, 98.2:100, 98.4:100, 98.5:100, 98.7:100, 98.9:100, 99:100, 99.2:100, 99.4:100, 99.5:100, 99.7:100, 99.8:100, 99.9:100, or 1:1.

[0076] In some possible embodiments, the area of ​​the first surface of the insulating layer 22 near the back contact cell is in the ratio of 96:100 to 1:1 to the area of ​​the back surface of the cell body 221. This further ensures that the third side is inside the first side and the fourth side is inside the second side. The spacing between adjacent back contact cells 21 will not expose the insulating layer 22, making the photovoltaic module more aesthetically pleasing.

[0077] For example, the ratio of the area of ​​the first surface of the insulating layer 22 near the back contact cell to the area of ​​the back surface of the battery body 221 can be 96:100, 96.04:100, 96.2:100, 96.5:100, 96.7:100, 96.9:100, 97:100, 97.1:100, 97.3:100, 97.5:100, 97.9:100, 98:100, 98.3:100, 98.5:100, 98.7:100, 98.9:100, 99:100, 99.2:100, 99.5:100, 99.7:100, 99.9:100, 99.9:100, or 1:1.

[0078] The area of ​​the first surface of the insulating layer 22 near the back contact cell refers to the area enclosed by the third side 222 and the fourth side 223 of the first surface of the insulating layer 22 near the back contact cell, which includes the area of ​​the through holes. The area of ​​the first surface of the insulating layer 22 near the back contact cell can be obtained through geometric measurement or imaging techniques. Images of the first surface of the insulating layer 22 near the back contact cell can be captured using a CCD camera, optical microscope, scanning electron microscope (SEM), or atomic force microscope (AFM), and the area of ​​the first surface can be calculated using image processing software. For example, if the first surface of the insulating layer 22 near the back contact cell is rectangular, the product of the side length L3 of the third side 222 and the side length L4 of the fourth side 223 of the insulating layer 22 is the area of ​​the first surface of the insulating layer 22 near the back contact cell. The method for determining the area of ​​the back surface of the battery body 221 is similar, and will not be repeated here. It should be noted that the methods for determining the area mentioned in this application can all be similar, and will not be repeated here.

[0079] In some possible embodiments, refer to Figure 3 In the composite back contact cell 2: the distance between the first side 2111 and the third side 222 is D1, as shown in the figure. Figure 4The distance from the collector grid line 212 adjacent to the first side 2111 to the first side 2111 is D2; 0.3×D2≤D1≤1.5×D2. Specifically, if D1 is too large, it may cause both polarity collector grid lines 212 adjacent to the first side 2111 to be exposed, which has a certain short circuit risk. If D1 is too small, it may increase the requirements for alignment and processing accuracy. If D2 is too large, it will result in a longer transport path for charge carriers at the edge of the battery body, resulting in transmission loss. If D2 is too small, it may affect the setting of the interconnection section 213. Therefore, in this application, the relationship between D1 and D2 is within the above range, which can not only reduce the short circuit risk, but also make the process window for processing and alignment wider, and the transport path of charge carriers at the edge of the battery body shorter, resulting in less transmission loss, and the processing window for the interconnection section 213 wider. For example, D1 can be 0.3×D2, 0.5×D2, 0.6×D2, 0.9×D2, 1×D2, 1.1×D2, 1.2×D2, 1.25×D2, 1.3×D2, 1.4×D2, or 1.5×D2.

[0080] Furthermore, with 0.3×D2≤D1≤1.0×D2, the insulation layer can cover all collector grid lines, further reducing the risk of short circuits.

[0081] It should be noted that when the distances between different positions on the first side 2111 and the third side 222 are not equal, the arithmetic mean of the distances at two or more positions can be taken as D1. In this application, the measurement of distances is similar, and to avoid repetition, it will not be elaborated further.

[0082] In some possible embodiments, refer to Figure 3 In the composite back contact cell 2: the distance between the second side 2112 and the fourth side 223 is D3, as shown in the reference. Figure 4The distance from the end of the collector grid line 212 to the second side 2112 is D4; 0.2×D4≤D3≤1.3×D2. Specifically, if D3 is too large, it may cause the ends of the collector grid lines 212 of both polarities to leak out, or even cause a large distance between the two ends to leak out, which has a certain short circuit risk. If D3 is too small, it may increase the requirements for alignment and processing accuracy. If D4 is too large, it will result in a longer transport path for charge carriers at the edge of the battery body, resulting in transmission loss. If D4 is too small, it may affect the setting of the interconnection section 213. Therefore, in this application, the relationship between D3 and D4 is within the above range, which can not only reduce the short circuit risk, but also make the process window for processing and alignment wider, and the transport path of charge carriers at the edge of the battery body shorter, resulting in less transmission loss, and the processing window for the interconnection section 213 wider. For example, D3 can be 0.20×D4, 0.23×D4, 0.25×D4, 0.3×D4, 0.4×D4, 0.5×D4, 0.7×D4, 0.8×D4, 1×D4, 1.1×D4, 1.2×D4, 1.25×D4, or 1.3×D4.

[0083] Furthermore, with 0.3×D4≤D3≤1.0×D4, the insulation layer can cover all collector grid lines, further reducing the risk of short circuits.

[0084] Figure 5 The left and top sides are both the inner sides of the photovoltaic module. Figure 5 This is just a schematic diagram of a photovoltaic module near a corner edge, for example. Figure 5 This is a schematic diagram showing the lower right edge of the photovoltaic module. In some possible embodiments, refer to... Figure 5 At the edge of the photovoltaic module: the conductive layer 11 extends to the outside of the insulating layer 22, meaning the conductive layer 11 is further out, which improves the reliability of the electrical connection between the back contact cell 21 and the conductive layer 11. The distance between the edge of the conductive layer 11 and the fourth side 223 of the adjacent insulating layer 22 is D5. (Refer to...) Figure 4 In the composite back-contact solar cell 2: the distance from the end of the current collector grid line 213 to the second side 2112 of the battery body is D4; 0.5×D4≤D5≤1.8×D4. Specifically, if D5 is too large, it may lead to material waste; if D5 is too small, it may lead to low electrical connection reliability between the back-contact solar cell and the conductive layer; if D4 is too large, it will result in a longer transport path for charge carriers at the edge of the battery body, leading to transmission loss; if D4 is too small, it may affect the setting of the interconnection section 213. Therefore, in this application, the relationship between D5 and D4 is within the above range, which can not only improve the electrical connection reliability between the back-contact solar cell and the conductive layer and reduce material waste, but also shorten the transport path of charge carriers at the edge of the battery body, reduce transmission loss, and widen the processing window of the interconnection section 213.

[0085] For example, D5 can be 0.5×D4, 0.52×D4, 0.55×D4, 0.59×D4, 0.6×D4, 0.62×D4, 0.65×D4, 0.68×D4, 0.7×D4, 0.71×D4, 0.72×D4, 0.75×D4, 0.79×D4, 0.9×D4, 1×D4, 1.1×D4, 1.2×D4, 1.25×D4, 1.3×D4, 1.4×D4, 1.5×D4, 1.6×D4, 1.7×D4, or 1.8×D4.

[0086] In some possible embodiments, refer to Figure 5 The conductive layer 11 is distributed in a finger-like structure, and adjacent finger-like structures 111 are isolated by waste wire grooves 112. At the edge of the photovoltaic module: the distance between the head edge of the waste wire groove 112 and the third side 222 of the adjacent insulating layer 22 is D6; the distance between the head edge of the finger-like structure and the adjacent edge in the conductive layer is D7, 0.3≤D6 / D7≤0.8. The photovoltaic module includes a long side and a short side, the length of which is greater than or equal to the length of the short side. Here, D6 can be the distance between the head edge of the waste wire groove 112 and the third side 222 of the adjacent insulating layer 22 near the short side in the photovoltaic module, and D7 can be the distance between the head edge of the waste wire groove 112 and the third side 222 of the conductive layer 11 near the insulating layer near the short side in the photovoltaic module. Specifically, if D6 is too large, the irregular current collector lines at the edge of the battery will be exposed, which may lead to a short circuit. If D6 is too small, the processing window may be narrow. Therefore, in this application, the relationship between D6 and D7 is within the above range, which can not only reduce the risk of short circuit, but also make the processing and alignment process window wider.

[0087] For example, D6 can be 0.3×D7, 0.32×D7, 0.35×D7, 0.39×D7, 0.4×D7, 0.42×D7, 0.45×D7, 0.48×D7, 0.5×D7, 0.51×D7, 0.52×D7, 0.55×D7, 0.59×D7, 0.6×D7, 0.61×D7, 0.65×D7, 0.69×D7, 0.7×D7, 0.73×D7, 0.75×D7, 0.79×D7, or 0.8×D7.

[0088] Figure 6 Only the location of the busbar and the mating relationship between the busbar 6 and the adjacent insulating layer 22 are shown; other structures are omitted. In some possible embodiments, refer to... Figure 6The photovoltaic module also includes: a busbar 6, on which at least a portion of the composite back-contact solar cell 2 is disposed; the extension direction of at least a portion of the busbar 6 is parallel to the extension direction of the collector grid line 212; in a direction perpendicular to the extension direction of the busbar 6: the dimension D13 of the portion of the insulating layer 22 located on the busbar 6 covers at least 2 / 3 of the width D8 of the busbar 6. The larger dimension covered by D13 in the direction of the width D8 of the busbar 6 indicates a larger overlap between the composite back-contact solar cell 2 and the busbar 6, avoiding microcracks or even cell cracking caused by excessive stress concentration due to a smaller overlap. Furthermore, D13 covers at least 4 / 5 of the width D8 of the busbar 6.

[0089] For example, D13 covers at least 2 / 3, 7 / 10, 11 / 15, 23 / 30, 4 / 5, 5 / 6, 13 / 15, 9 / 10, 1, etc. of the width of D8 of busbar 6.

[0090] In some possible embodiments, the insulation layer 22 is a single or multiple layer structure, such as a single-layer, two-layer, three-layer, or four-layer structure. Each layer comprises, by mass ratio, at least 20% linear low-density polyethylene, at least 30% block copolymer polypropylene, and at least 5% compatible toughened ethylene octene copolymer. Specifically, linear low-density polyethylene has good adhesive properties, but its melting point is relatively low, such as 105°C to 110°C. After melting, linear low-density polyethylene undergoes significant creep. Block copolymer polypropylene can improve temperature resistance; for example, its melting point is around 160°C, and it can serve as a high-temperature resistant skeletal support in the insulation layer. The compatible toughened ethylene octene copolymer contains fragments of both block copolymer polypropylene and linear low-density polyethylene, allowing for good blending of the two materials. The linear low-density polyethylene in insulation layer 22 accounts for less than 20% of the total mass, resulting in poor adhesion. The block copolymer polypropylene in insulation layer 22 accounts for less than 30% of the total mass, resulting in poor temperature resistance and support properties. The compatible toughening ethylene octene copolymer in insulation layer 22 accounts for less than 5% of the total mass, resulting in poor mixing effect between linear low-density polyethylene and block copolymer polypropylene. In summary, the insulation layer 22 of the above materials has good adhesion and also has certain temperature resistance and support properties.

[0091] For example, in the insulation layer, the mass percentage of linear low-density polyethylene can be 20%, 22%, 25%, 28%, 30%, 32%, 35%, 39%, or 40% by mass. For example, in the insulation layer, the mass percentage of block copolymer polypropylene can be 30%, 32%, 35%, 38%, 40%, 42%, 45%, 49%, or 50% by mass. For example, in the insulation layer, the mass percentage of compatible toughened ethylene octene copolymer can be 5%, 5.3%, 5.9%, 6%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.9%, 8%, 8.2%, 8.5%, 8.9%, 9%, 9.3%, 9.5%, or 10% by mass.

[0092] In some possible embodiments, the insulating layer 22 is a thermoplastic insulating layer or a cross-linked thermo / photocurable insulating layer. Specifically, cross-linked thermo / photocurable insulating layers have lower costs, while thermoplastic insulating layers have better adhesive properties, resulting in better encapsulation and reliability.

[0093] In some possible embodiments, the photovoltaic module further includes a gap film (not shown in the figure), located on the side of the conductive layer 11 near the insulating layer 22, and corresponding to the spacing position of the adjacent back contact cells 21. This gap film contains pigment, which can be white or black. For white modules, the pigment is primarily white and serves as a reflective film; for black modules, the pigment is primarily black. By weight, the gap film comprises at least 20% linear low-density polyethylene, at least 30% block copolymer polypropylene, and at least 5% compatible toughened ethylene octene copolymer. The main materials of this gap film are the same as those of the aforementioned insulating layer 22. This gap film can be obtained by adding pigment to the scraps of the aforementioned insulating layer 22, resulting in high material reuse, saving process steps and costs.

[0094] For example, the insulating layer 22 can be formed by co-extrusion. If the head and tail of the co-extruded insulating layer 22 are uneven in thickness or irregular in shape, the head and tail can be cut off, and the cut-off scraps can be reused as gap film. As another example, the open portion of the insulating layer 22 can also be reused as gap film.

[0095] The thickness of the gap film can range from 25μm to 100μm, and further from 35μm to 55μm. If the gap film is too thick, it may lift up the back contact cell, resulting in poor connection reliability between the conductor 5 and the conductive layer 12. If the gap film is too thin, the gap-blocking effect is poor. Therefore, in this application, the thickness of the gap film not only ensures the connection reliability between the conductor and the conductive layer, but also ensures the blocking effect. The thickness of the gap film is parallel to the direction of the thickness of the photovoltaic module.

[0096] For example, the thickness of the gap film can be 25μm, 28μm, 30μm, 35μm, 38μm, 40μm, 42μm, 45μm, 47μm, 50μm, 52μm, 55μm, 58μm, 60μm, 63μm, 65μm, 69μm, 70μm, 72μm, 77μm, 75μm, 80μm, 81μm, 85μm, 89μm, 90μm, 92μm, 95μm, 99μm, or 100μm.

[0097] In some possible embodiments, the gap film comprises, by weight percentage, 5% to 8% rutile titanium dioxide or 6% to 12% perylene-based high-reflectivity black pigment. Rutile titanium dioxide can be present as a white pigment, and perylene-based high-reflectivity black pigment as a black pigment. If the weight percentage of rutile titanium dioxide in the gap film is less than 5%, the color of the gap film will not meet requirements; if the weight percentage of rutile titanium dioxide is greater than 8%, it may affect other properties of the gap film. Therefore, a weight percentage of 5% to 8% rutile titanium dioxide in the gap film not only meets the color requirements but also provides good adhesion. Similarly, a weight percentage of 6% to 12% perylene-based high-reflectivity black pigment in the gap film not only meets the color requirements but also provides good adhesion.

[0098] For example, gap films include: 5%, 5.2%, 5.5%, 5.7%, 6%, 6.1%, 6.4%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.9%, and 8% rutile titanium dioxide, or 6%, 6.1%, 6.3%, 6.5%, 6.9%, 7%, 7.1%, 7.3%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.7%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, 10%, 10.2%, 10.5%, 10.8%, 11%, 11.3%, 11.5%, 11.9%, and 12% perylene-based high-reflection pigments.

[0099] In some possible embodiments, refer to Figure 4 The back contact cell 21 also includes a plurality of interconnecting portions 213 disposed on the side of the current collector grid line 212 away from the cell body. These interconnecting portions 213 may be electrode pads, etc. The maximum dimension of the interconnecting portion 213 along the extending direction of the first side 2111 is D8. (Refer to...) Figure 2 , Figure 3 and Figure 5Along the extension direction of the third side 222, the length of the through hole 221 is D9; 1.1×D8≤D9≤3×D8. Specifically, if D9 is too much larger than D8, it will lead to the exposure of heterogeneous collector grid lines or heterogeneous electrodes, posing a short circuit risk. If D9 is too small compared to D8, under the influence of processing errors, there may be a problem that some interconnects 213 cannot leak out from the through hole 221, resulting in poor current collection effect. Therefore, in this application, the relationship between D9 and D8 is within the above range, which can not only avoid short circuits but also ensure current collection effect.

[0100] For example, D9 can be 1.1×D8, 1.2×D8, 1.3×D8, 1.4×D8, 1.5×D8, 1.6×D8, 1.7×D8, 1.8×D8, 1.9×D8, 2×D8, 2.1×D8, 2.2×D8, 2.3×D8, 2.5×D8, 2.8×D8, 2.9×D8, or 3×D8.

[0101] It should be noted that, referring to Figure 3 and Figure 5 The through-hole here can be a long slot, and one through-hole can correspond to the positions of multiple collector grid lines. In this case, 1.2×D8≤D9≤2.2×D8. Alternatively, refer to... Figure 7 The through-hole here can be a round hole, and one through-hole can be aligned with the corresponding position of a collector wire. In this case, 1.1×D8≤D9≤3×D8. Both of the above situations are within the protection scope of this application.

[0102] In some possible embodiments, refer to Figure 2 , Figure 3 and Figure 5 Along the extension direction of the third side 222, the length of the through hole 221 is D9; refer to Figure 5 The conductive layer 11 is distributed in finger-like structures 111, and adjacent finger-like structures 111 are isolated by waste wire grooves 112. Along the extension direction of the third side 222, the distance between adjacent waste wire grooves 112 is D12; 0.05≤D9 / D12≤0.3. Specifically, if D9 is too large, the via may cross the waste wire groove 112, posing a short-circuit risk. If D9 is too small, the via 221 is smaller, resulting in less conductor in the via 221, leading to poor electrical connection between the collector grid and the conductive layer 11. In this application, 0.05≤D9 / D12≤0.3 reduces the short-circuit risk and improves the electrical connection between the collector grid and the conductive layer 11.

[0103] It should be noted that the waste wire trough 112 here can be composed of a straight section and a curved section that is continuous with the straight section. The end of the waste wire trough 112 can be a curved section, and the middle part of the waste wire trough can usually be a straight section. Here, D12 can be the distance between the straight segments of adjacent waste wire grooves 112 along the extension direction of the third side 222. For example, D12 can be the distance between the centers of the straight segments of adjacent waste wire grooves 112 along the extension direction of the third side 222. Or, D12 can be the distance between the boundary lines of the straight segments of adjacent waste wire grooves 112 along the extension direction of the third side 222. Whether D12 includes the width of the straight segments of waste wire grooves 112 along the extension direction of the third side 222 is not specifically limited. If D12 includes the width of the straight segments of waste wire grooves 112 along the extension direction of the third side 222, it can include the width of one straight segment of waste wire groove 112 along the extension direction of the third side 222, or the width of two straight segments of waste wire grooves 112 along the extension direction of the third side 222. There is no specific limitation on this. Furthermore, the straight segments of adjacent waste wire grooves 112 can be parallel to each other, in which case D12 is equal at different positions; or, the straight segments of adjacent waste wire grooves 112 can be extended and intersecting, with D12 being the smallest at one end near the intersection and the largest at the other end, meaning D12 is not equal at different positions. The 0.05 ≤ D9 / D12 ≤ 0.3 applies to all D12 values ​​from the smallest to the largest. For example, D9 / D12 can be 0.05, 0.09, 0.1, 0.12, 0.15, 0.18, 0.2, 0.23, 0.25, 0.28, or 0.3.

[0104] In some possible embodiments, 0.08 ≤ D9 / D12 ≤ 0.25; here, D12 is the minimum distance between adjacent waste wire grooves 112 along the extension direction of the third side 222. This range applies when the straight segments of adjacent waste wire grooves 112 intersect after extension. At the end near the intersection after extension, D12 is the minimum distance between adjacent waste wire grooves 112 along the extension direction of the third side 222. Therefore, at the minimum distance between adjacent waste wire grooves 112 along the extension direction of the third side 222, the problem of excessively large through-holes spanning the waste wire grooves can be avoided, further reducing the risk of short circuits, while also ensuring the electrical connection effect between the collector grid and the conductive layer 11.

[0105] For example, when D12 is the minimum distance between adjacent waste wire grooves 112 along the extension direction of the third side 222, D9 / D12 can be 0.08, 0.1, 0.13, 0.15, 0.19, 0.2, 0.21, or 0.25.

[0106] It should be noted that in the waste wire groove 112, the curved section can be either arc-shaped or non-arc-shaped, and there is no specific limitation on this.

[0107] In some possible embodiments, refer to Figure 3 The through-hole 221 extends along the extension direction of the fourth side 223. The distance between the interconnecting portions 213 at the two opposite ends is D10 along the extension direction of the second side 2112. The length of the through-hole 221 along the extension direction of the fourth side 223 is D11; 1.05×D10≤D11≤1.12×D10. Specifically, if D11 is much larger than D10, the through-hole area of ​​the insulating layer will be too large, resulting in an insufficiently small or narrow area at the edge of the insulating layer without through-holes. During lamination, the insulating layer, receiving pressure from the back contact cell and the conductive layer, is prone to cracking or damage at its edges, affecting the yield and reliability of the module. Furthermore, the relative size relationship between D11 and D10 is also related to the amount of insulating layer used. More specifically, if D11 is much larger than D10, the distance between the through-hole and the third side 222 will be too small, making it prone to cracking or damage at the location between the through-hole and the third side 222. If D11 is too small compared to D10, due to processing errors, some interconnects 213 may not be able to leak out from the through-hole 221, resulting in poor current collection performance. Therefore, in this application, the relationship between D10 and D11 is within the above range, which ensures that the interconnects on the cell are fully exposed, thus ensuring the current collection performance. At the same time, it reduces the amount of insulation layer used, reduces the module cost, and also takes into account the yield of the manufacturing process.

[0108] For example, D11 can be 1.05×D10, 1.06×D10, 1.07×D10, 1.08×D10, 1.09×D10, 1.1×D10, 1.11×D10, or 1.12×D10.

[0109] In some possible embodiments, the battery body includes corners located at the intersection of the first side 2111 and the second side 2112, with at least two corners extending beyond the insulating layer 22. Specifically, when the shape of the insulating layer 22 is not square enough or not precise enough, at least two corners of the battery body need to be exposed for positioning to improve alignment accuracy. For example, when forming a large-sized insulating layer, and then using laser cutting to cut the insulating layer composite with the back contact battery cell, the shape of the edge of the insulating layer may be irregular due to the thermal effect of the laser, which may prevent the insulating layer from serving as a positioning reference. Therefore, at least two corners of the battery body are exposed for positioning reference. For example, two, three, or four corners of the battery body may be exposed.

[0110] In some possible embodiments, the insulating layer 22 includes an edge portion and an inner portion located inside the edge; the thickness of the edge portion is greater than the height of the inner portion. Specifically, the edge portion of the insulating layer 22 is the location where the insulating layer 22 is bonded to the back contact cell 21. A slightly larger thickness in the edge portion of the insulating layer 22 provides better adhesion and facilitates tight bonding with the back contact cell 21. The thickness difference between the two portions is not specifically limited. The relative dimensions of the edge portion and the inner portion are also not limited.

[0111] This application also provides a method for preparing a photovoltaic module, which is used to prepare any of the aforementioned photovoltaic modules. The preparation method includes the following steps.

[0112] Step S1, providing an insulating layer and a back contact battery cell; the back contact battery cell includes: a battery body, and current collector grid lines located on the backlight side of the battery body; the insulating layer is provided with through holes penetrating the insulating layer at positions corresponding to some of the current collector grid lines.

[0113] It should be noted that, referring to Figure 3 and Figure 5 The through-hole here can be an elongated slot, and one through-hole can correspond to the positions of multiple collector wires. Or, refer to... Figure 7 The through-hole here can be a round hole, and one through-hole can be aligned with the corresponding position of a collector wire. Both of these situations are within the protection scope of this application.

[0114] Step S2: The insulating layer is laminated onto the backlight side of the back contact battery cell to obtain a composite back contact battery cell; the through-hole is filled with a conductor; the backlight surface of the battery body includes: an intersecting first side and a second side; the first surface of the insulating layer near the back contact battery cell includes: an intersecting third side and a fourth side; the third side is located within the first side, and the fourth side is located within the second side; the extension directions of the first side and the third side are both parallel to the extension directions of the current collector grid lines; the extension directions of the second side and the fourth side are parallel; the length of the first side is L1, the side length of the second side is L2, the length of the third side is L3, and the side length of the fourth side is L4; wherein, L3:L1 = 96:100 to 1:1, and / or, L4:L2 = 95:100 to 1:1.

[0115] Step S3: Conductively interconnect the composite back contact cell with the conductive backplate; the conductive backplate includes: a conductive layer and a backplate stacked together; the insulating layer and the conductive layer are adjacent.

[0116] In some possible embodiments, the step of providing the insulating layer in step S1 includes: forming a complete insulating layer through multilayer co-extrusion; and cutting the complete insulating layer into multiple insulating layers by die-cutting or laser cutting. The co-extrusion method for forming the complete insulating layer in this application is simple, has fewer steps, and is less expensive. Die-cutting has low production costs, produces more regular shapes of the cut insulating layers, and does not affect the thickness of the insulating layer at various points. The multilayer co-extrusion here can be two, three, or four layers, etc., and each layer can contain, by mass ratio, the aforementioned: at least 20% linear low-density polyethylene, at least 30% block copolymer polypropylene, and at least 5% compatible toughened ethylene octene copolymer.

[0117] In some possible embodiments, prior to step S1, the method may further include: setting conductors 5 at positions corresponding to some of the collector grid lines, i.e., setting conductors 5 first and then laminating them together. This can reduce the material used for conductors 5 and lower costs. The conductors 5 can be set using printing methods such as stencil printing or screen printing.

[0118] In some possible embodiments, after the aforementioned step S1, the method may further include: setting a conductor 5 at the position corresponding to the current collector grid line 212 inside the through hole 211, that is, first combining the insulating layer 22 and the back contact cell 21, and then setting the conductor 5. In this case, even if there is splashing of the slurry of the conductor 5 during the process of setting the conductor 5, the splashed part is located on the side of the insulating layer away from the battery, and will not cause a short circuit problem.

[0119] In some possible embodiments, the aforementioned step S2 may include steps S21 and S22. Step S21: Align the insulating layer 22 with the back-light side of the back-contact battery cell 21 using a vacuum adsorption method; the adsorption positions include: each corner of the insulating layer 22, and at least four other positions; the distance between adjacent adsorption positions is less than or equal to 1 / 3 of the length L4 of the fourth side 223 of the insulating layer 22. Specifically, adsorbing only the corners of the insulating layer 22 is usually insufficient to flatten the insulating layer 22 with through holes, so at least four other positions are needed. The other four positions are not limited, but the distance between adjacent adsorption positions is less than or equal to 1 / 3 of the length L4 of the fourth side 223 of the insulating layer 22, and the distance between adjacent adsorption positions is not too large, so that the insulating layer 22 with through holes can be flattened for alignment. For example, the spacing between adjacent adsorption sites is 1 / 3, 1 / 4, 1 / 5, 1 / 6, 1 / 7, 1 / 8, 1 / 9, 1 / 10, 1 / 11, or 1 / 12 of the length L4 of the fourth side 223 of the non-insulating layer 22.

[0120] Step S22: Heat the insulating layer to bond it to the backlight side of the back contact battery cell; and / or, adhesively bond the insulating layer to the backlight side of the back contact battery cell; the heating bonding temperature is 100°C to 200°C, and further, the temperature range is 130°C to 165°C; specifically, if the temperature is too low, the insulating layer cannot be firmly bonded to the backlight side of the back contact battery cell, and if the temperature is too high, it may cause holes in the insulating layer. Therefore, the heating bonding temperature is 100°C to 200°C, which not only firmly bonds the insulating layer to the backlight side of the back contact battery cell, but also avoids holes in the insulating layer.

[0121] For example, the heating temperature for composite bonding can be 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, or 200℃.

[0122] The adhesives used in the aforementioned adhesive bonding include low-temperature curing acrylic adhesives, which have good bonding properties.

[0123] In some possible embodiments, the aforementioned step S3 may include: electrically interconnecting the composite back contact cell 2 with the conductive backplate 1 by heating and pressing; the heating and pressing temperature is 220°C to 260°C, further 240°C to 250°C, and the pressing pressure is 10 MPa to 50 MPa, further 15 MPa to 30 MPa. Specifically, if the pressing temperature and pressure are too low, the conductive interconnection between the composite back contact cell 2 and the conductive backplate 1 may be unreliable; if the pressing pressure is too high, it may cause the cell to crack or break. Therefore, the heating and pressing temperature can be 220°C, 223°C, 230°C, 235°C, 240°C, 242°C, 245°C, 249°C, 250°C, 252°C, 255°C, 257°C, or 260°C. The downward pressure can be 10MPa, 12MPa, 15MPa, 17MPa, 20MPa, 21MPa, 25MPa, 28MPa, 30MPa, 33MPa, 35MPa, 39MPa, 40MPa, 42MPa, 45MPa, 48MPa, or 50MPa.

[0124] In some possible embodiments, the preparation method may further include placing a gap film on the side of the conductive layer near the insulating layer, corresponding to the spacing between adjacent back contact cells. The gap film can be bonded to the conductive layer by heating at a temperature of 110°C to 150°C, more specifically 130°C to 140°C, for a duration of 5 to 7 seconds. Specifically, excessively high temperatures or prolonged heating times may cause the gap film to tear, while excessively low temperatures or short heating times may result in insufficient adhesion. Therefore, this application ensures strong adhesion and avoids tearing of the gap film.

[0125] It should be noted that the preparation method provided in this application may also include pre-lamination and lamination steps. The pre-lamination temperature is 122℃-128℃, during which gas venting of the component is completed; the lamination temperature is 157℃-165℃, during which the component is encapsulated.

[0126] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0127] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A photovoltaic module, characterized in that, include: A conductive backsheet and multiple composite back contact cells located on the conductive backsheet; The conductive backplate includes: a conductive layer and a backplate stacked together; The composite back-contact solar cell includes: a back-contact solar cell and an insulating layer located on the backlight side of the back-contact solar cell, the insulating layer and the conductive layer being adjacent; the insulating layer does not extend beyond the back-contact solar cell; the back-contact solar cell includes: a battery body, and current collector grid lines located on the backlight side of the battery body, the insulating layer having through holes at positions corresponding to a portion of the current collector grid lines, the through holes being filled with a conductor; the backlight surface of the battery body includes: an intersecting first side and a second side; the first surface of the insulating layer near the back-contact solar cell includes: an intersecting third side and a fourth side; the extension directions of the first side and the third side are both parallel to the extension directions of the current collector grid lines; the extension directions of the second side and the fourth side are parallel; the length of the first side is L1, the length of the second side is L2, the length of the third side is L3, and the length of the fourth side is L4. Wherein, L3:L1 = 96:100 to 1:1, and / or, L4:L2 = 95:100 to 1:

1.

2. The photovoltaic module according to claim 1, characterized in that, The area ratio of the first surface to the backlight surface is 96:100 to 1:

1.

3. The photovoltaic module according to claim 1, characterized in that, In the composite back contact cell: the distance between the first side and the third side is D1, and the distance from the current collector grid line adjacent to the first side to the first side is D2; 0.3×D2≤D1≤1.5×D2.

4. The photovoltaic module according to claim 1, characterized in that, In the composite back contact cell: the distance between the second side and the fourth side is D3, and the distance from the end of the current collector grid line to the second side is D4; 0.2×D4≤D3≤1.3×D4.

5. The photovoltaic module according to claim 1, characterized in that, At the edge of the photovoltaic module: the conductive layer extends to the outside of the insulating layer; the distance between the edge of the conductive layer and the adjacent fourth side is D5; in the composite back contact cell: the distance from the end of the current collector grid line to the second side is D4; 0.5×D4≤D5≤1.8×D4.

6. The photovoltaic module according to claim 1, characterized in that, The conductive layer is distributed in a finger-like structure, and adjacent finger-like structures are isolated by waste wire grooves; at the edge of the photovoltaic module: the distance between the head edge of the waste wire groove and the adjacent third side is D6; the distance between the head edge of the waste wire groove and the adjacent edge of the conductive layer is D7, 0.3≤D6 / D7≤0.

8.

7. The photovoltaic module according to claim 1, characterized in that, Also includes: The busbar has at least a portion of the composite back contact cells disposed on it; the extension direction of at least a portion of the busbar is parallel to the extension direction of the current collector grid lines. In a direction perpendicular to the extension direction of the busbar: the dimension of the portion of the insulation layer located on the busbar covers at least 2 / 3 of the width of the busbar.

8. The photovoltaic module according to claim 1, characterized in that, The insulation layer is a single or multiple layer structure; each layer comprises, by weight ratio: at least 20% linear low-density polyethylene, at least 30% block copolymer polypropylene, and at least 5% compatible toughened ethylene octene copolymer; and / or, The insulating layer is a thermoplastic insulating layer or a cross-linked heat / photocurable insulating layer.

9. The photovoltaic module according to claim 1, characterized in that, Also includes: The gap film is located on the side of the conductive layer close to the insulating layer, and corresponds to the spacing position between adjacent back contact cells; The gap film contains pigment and, by weight ratio, comprises at least 20% linear low-density polyethylene, at least 30% block copolymer polypropylene, and at least 5% compatible toughened ethylene octene copolymer.

10. The photovoltaic module according to claim 9, characterized in that, By weight percentage, the gap film comprises: 5% to 8% rutile titanium dioxide, or 6% to 12% perylene-based high-reflectivity black pigment; and / or, The thickness of the gap film ranges from 25 μm to 100 μm.

11. The photovoltaic module according to any one of claims 1 to 10, characterized in that, The back contact battery cell further includes: a plurality of interconnecting portions disposed on the side of the current collector grid line away from the battery body; The maximum dimension of the interconnect portion along the extension direction of the first side is D8, and the length of the through hole along the extension direction of the third side is D9; 1.1×D8≤D9≤3×D8; and / or, The through hole extends along the extension direction of the fourth side. In the extension direction of the second side, the distance between the interconnecting portions of the two opposite ends is D10. Along the extension direction of the fourth side, the length of the through hole is D11; 1.05×D10≤D11≤1.12×D10.

12. The photovoltaic module according to any one of claims 1 to 10, characterized in that, Along the extension direction of the third side, the length of the through hole is D9; the conductive layer is distributed in a finger-like structure, and adjacent finger-like structures are isolated by waste wire grooves; Along the extension direction of the third side, the distance between adjacent waste wire grooves is D12; 0.05≤D9 / D12≤0.

3.

13. The photovoltaic module according to claim 12, characterized in that, 0.08≤D9 / D12≤0.25; where D12 is the minimum distance between adjacent waste wire grooves along the extension direction of the third side.

14. The photovoltaic module according to any one of claims 1 to 10, characterized in that, The battery body includes: a corner located at the intersection of the first side and the second side, wherein at least two corners of the battery body extend beyond the insulating layer; and / or, The insulating layer includes an edge portion and an inner portion located inside the edge; the thickness of the edge portion is greater than the height of the inner portion.

15. A method for preparing a photovoltaic module, characterized in that, include: Provides insulation and back contact cells; The back contact battery cell includes: a battery body, and current collector grid lines located on the backlight side of the battery body; the insulating layer has through holes at positions corresponding to some of the current collector grid lines; The insulating layer is laminated onto the back-light side of the back-contact battery cell to obtain a composite back-contact battery cell; the insulating layer does not extend beyond the back-contact battery cell; the through-hole is filled with a conductor; the back-light surface of the battery body includes: an intersecting first side and a second side; the first surface of the insulating layer near the back-contact battery cell includes: an intersecting third side and a fourth side; the extension directions of the first side and the third side are both parallel to the extension directions of the current collector grid lines; the extension directions of the second side and the fourth side are parallel; the length of the first side is L1, the length of the second side is L2, the length of the third side is L3, and the length of the fourth side is L4; wherein, L3:L1 = 96:100 to 1:1, and / or, L4:L2 = 95:100 to 1:1; The composite back contact solar cell is electrically interconnected with a conductive backplate; the conductive backplate includes: a conductive layer and a backplate stacked together; the insulating layer and the conductive layer are adjacent to each other.

16. The method for preparing a photovoltaic module according to claim 15, characterized in that, The steps for providing the insulating layer include: The insulation layer is formed by multi-layer co-extrusion. Multiple insulating layers are obtained by cutting the entire insulating layer using die-cutting or laser cutting methods.

17. The method for preparing a photovoltaic module according to claim 15, characterized in that, Before laminating the insulating layer onto the back-light side of the back-contact solar cell, the method further includes: placing a conductor at positions corresponding to some of the current collector grid lines; or, After the insulating layer is laminated to the backlight side of the back contact cell, the method further includes: placing a conductor at the position corresponding to the current collector grid line inside the through hole.

18. The method for preparing a photovoltaic module according to claim 15, characterized in that, The insulating layer is laminated onto the backlight side of the back contact cell, including: The insulating layer is aligned with the back-light side of the back-contact battery cell using a vacuum adsorption method; the adsorption positions include: each corner of the insulating layer, and at least four other positions; the distance between adjacent adsorption positions is less than or equal to 1 / 3 of L4; The insulating layer is heat-bonded to the back-light side of the back contact cell; and / or the insulating layer is adhesively bonded to the back-light side of the back contact cell; the heat-bonding temperature is 100°C to 200°C; the adhesive used for adhesive bonding includes a low-temperature curing acrylic adhesive.

19. The method for preparing a photovoltaic module according to any one of claims 15 to 18, characterized in that, Conductively interconnecting the composite back contact solar cell with the conductive backplate includes: The composite back contact cell is electrically interconnected with the conductive backplate by heating and pressing; the heating and pressing temperature is 220°C to 260°C, and the pressing pressure is 10MPa to 50MPa.

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