Photovoltaic module

Abstract

The photovoltaic module comprises a bus bar and at least two battery strings, the bus bar is used for electrically connecting the battery strings, each battery string comprises a welding strip and at least two battery pieces, at least two bonding pads distributed at intervals are arranged on the back faces of the battery pieces in the first direction, and the bonding pads are used for welding the welding strips and the battery pieces. In the thickness direction of the battery piece, the surface, away from the bonding pad, of the welding strip is directly welded to the bus bar, at least part of the bus bar and at least part of the bonding pad are arranged in a staggered mode in the first direction, and therefore the welding position of the at least part of the bonding pad and the welding strip is away from the welding position of the welding strip and the at least part of the corresponding bus bar. In the subsequent process of welding the welding strip and the corresponding at least part of the bus bar, no heat is transferred downwards to the welding position of the at least part of the bonding pad and the welding strip, the risk of soldering tin melting is avoided, the risk of pseudo soldering at the joint of the bonding pad and the welding strip is reduced, and the photovoltaic module has good electric energy transmission efficiency.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and particularly to a photovoltaic module. Background Art

[0002] In the prior art, the bus bar and the cell are placed on the same plane, and the bus bar occupies a part of the area in the photovoltaic module, reducing the effective sunlight-receiving area of the photovoltaic module, and decreasing the area utilization rate and the module power of the photovoltaic module. Therefore, the bus bar can be welded on the back of the cell. However, during the welding process of the bus bar and the solder tape, the pad is located below the bus bar, and there is a risk of poor welding at the welding position between the pad and the solder tape. Summary of the Invention

[0003] The present application provides a photovoltaic module for solving the problem of poor welding at the welding position between the pad and the solder tape during the welding process of the bus bar and the solder tape.

[0004] The present application provides a photovoltaic module, which includes a bus bar and at least two cell strings. The bus bar is used to electrically connect the cell strings. The cell string includes a solder tape and at least two cells. Along a first direction, at least two spaced-apart pads are provided on the back surface of the cell. The pads are used to weld the solder tape to the cell. Along the thickness direction of the cell, the surface of the solder tape facing away from the pad is directly welded to the bus bar;

[0005] At least part of the bus bar and at least part of the pads are arranged in a staggered manner along the first direction.

[0006] In the present application, when at least part of the bus bar and at least part of the pads are arranged in a staggered manner along the first direction, even if at least part of the bus bar and at least part of the pads do not overlap in the projection along the thickness direction of the photovoltaic module, so that the welding position of at least part of the pads and the solder tape is far from the welding position of the solder tape and the corresponding at least part of the bus bar. Therefore, when at least part of the pads are welded to the solder tape by solder first, and then during the direct welding process of the solder tape and the corresponding at least part of the bus bar, there is no welding heat transferred downward to the welding position of at least part of the pads and the solder tape, thereby avoiding the risk of solder melting, reducing the risk of poor welding at the connection between the pads and the solder tape, improving the stability and firmness of the connection between the pads and the solder tape, making the photovoltaic module have good structural stability, making the photovoltaic module have good electric energy transmission efficiency, and thus being beneficial to improving the photoelectric conversion efficiency of the photovoltaic module.

[0007] In this solution, the cell at least includes a first region, and the bus bar and the pad in the first region are arranged in a staggered manner along the first direction;

[0008] When the cell is a back-contact cell, along the first direction, the pads closest to both sides of the bus bar have a first distance D1, satisfying 13 mm ≤ D1 ≤ 15 mm;

[0009] Along the first direction, the size of the bus bar is d, satisfying 8 mm < d < 13 mm.

[0010] In this solution, along the first direction, there is a second distance D2 between adjacent pads on the same side of the bus bar, satisfying 5 mm < D2 < 10 mm.

[0011] In this solution, the cell further includes a second region, and the bus bar in the second region overlaps at least partially with at least some of the pads along the first direction.

[0012] In this solution, a conductive adhesive is provided at least at some positions in the second region, and the conductive adhesive is used to electrically connect the pads and the solder tape.

[0013] In this solution, along the second direction, the size of the conductive adhesive is L, satisfying 0.3 mm < L < 1 mm.

[0014] In this solution, along the thickness direction of the cell, the thickness of the conductive adhesive is H, satisfying 20 μm < H < 180 μm.

[0015] In this solution, the material of the conductive adhesive is a mixture of silver and resin.

[0016] In this solution, along the second direction, the size of the solder tape is M, satisfying 0.3 mm < M < 1 mm, and the size of the pad is N, satisfying 0.3 mm < N < 1.2 mm.

[0017] In this solution, the cell is a whole cell or a segmented cell, and / or, two adjacent cells overlap each other.

[0018] It should be understood that the above general description and the following detailed description are only exemplary and do not limit this application. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of a battery string with a back-contact cell provided by this application in a specific embodiment;

[0020] Figure 2 For Figure 1 It is a schematic structural diagram of the cell shown in in a specific embodiment, showing the first region in the battery string;

[0021] Figure 3The figure is a schematic structural view of a battery string with back-contact cells provided in this application in another specific embodiment;

[0022] Figure 4 is Figure 3 a schematic structural view of the cells in a partial area shown in [a certain figure] in a specific embodiment, showing the second area in the battery string;

[0023] Figure 5 is Figure 4 a cross-sectional view of the battery string in [a certain figure] in a specific embodiment;

[0024] Figure 6 is Figure 4 a cross-sectional view of the battery string in [a certain figure] in a specific embodiment.

[0025] Explanation of reference numerals:

[0026] 1 - Battery string;

[0027] 11 - Battery cell;

[0028] 12 - Pad;

[0029] 13 - Welding ribbon;

[0030] 14 - Bus bar;

[0031] 15 - Conductive adhesive.

[0032] The accompanying drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with this application, and are used together with the specification to explain the principles of this application. Detailed implementation manners

[0033] For a better understanding of the technical solutions of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0034] In a specific embodiment, the following further describes this application in detail through specific embodiments and with reference to the accompanying drawings.

[0035] It should be clear that the described embodiments are only a part of the embodiments of this application, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts belong to the scope protected by this application.

[0036] The terms used in the embodiments of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms "a", "the" and "said" used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0037] It should be understood that the term "and / or" used herein is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0038] It should be noted that the orientation terms such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described from the perspective shown in the drawings and should not be construed as limitations on the embodiments of the present application. In addition, in the context, it should also be understood that when it is mentioned that an element is connected "above" or "below" another element, it can not only be directly connected "above" or "below" another element, but also be indirectly connected "above" or "below" another element through an intermediate element.

[0039] In the prior art, the bus bar and the battery cell are placed on the same plane, and the bus bar occupies a part of the area in the photovoltaic module, reducing the effective sunlight-receiving area of the photovoltaic module, and decreasing the area utilization rate and the module power of the photovoltaic module. Therefore, the bus bar can be welded on the back of the battery. To achieve the welding, usually a plurality of pads (pad points) are provided on the back of the battery, and solder paste, such as solder, is coated on the pads (pad points). The battery cell is welded to the solder tape through the pads (pad points) to form a solar cell string, and then the solder tape is welded to the bus bar. However, during the welding process of the bus bar and the solder tape, certain heat is generated in this welding process, and there is a risk that the heat is transferred downward to the welding position of the pad (pad point) and the solder tape, resulting in the risk of melting the solder, and further there is a risk of poor welding at the welding position of the pad (pad point) and the solder tape, thus affecting the electric energy transmission efficiency of the battery.

[0040] To solve the above problems, the present application provides a photovoltaic module. When the battery cell 11 is a back-contact battery, as Figures 1-3 shown, the photovoltaic module includes a bus bar 14 and at least two battery strings 1. The bus bar 14 is used to electrically connect the battery strings 1. The battery string 1 includes a solder tape 13 and at least two battery cells 11. Along the first direction X, at least two spaced-apart pads 12 (pad points) are provided on the back surface of the battery cell 11. The pads 12 (pad points) are used to weld the solder tape 13 to the battery cell 11. Along the thickness direction of the battery cell 11, the surface of the solder tape 13 facing away from the pads 12 (pad points) is directly welded to the bus bar 14;

[0041] At least a part of the bus bar 14 and at least a part of the pads 12 (pad points) are arranged in a staggered manner along the first direction X.

[0042] It should be noted that the first direction X and the second direction Y mentioned herein can be referred to Figure 1In an embodiment, the first direction X can be the length direction of the solder strip 13, and the second direction Y can be the width direction of the solder strip 13. Therefore, the first direction X and the second direction Y are perpendicular to each other.

[0043] In the present application, when at least part of the bus bar 14 and at least part of the pad 12 (pad point) are arranged offset in the first direction X, that is, the projections of at least part of the bus bar 14 and at least part of the pad 12 (pad point) in the thickness direction of the solar cell 11 do not coincide, so that the position where the at least part of the pad 12 (pad point) is welded to the solder strip 13 is far from the position where the solder strip 13 is welded to the corresponding at least part of the bus bar 14. Therefore, when the at least part of the pad 12 (pad point) is welded to the solder strip 13 through solder, subsequently, during the process of directly welding the solder strip 13 to the corresponding at least part of the bus bar 14, there is no welding heat transferring downward to the position where the at least part of the pad 12 (pad point) is welded to the solder strip 13, thereby avoiding the risk of melting the solder due to heat, reducing the risk of solder joint failure at the connection between the pad 12 (pad point) and the solder strip 13, improving the stability and firmness of the connection between the pad 12 (pad point) and the solder strip 13, making the photovoltaic module have good structural stability, having good electrical energy transmission efficiency, and thus being beneficial to improving the photoelectric conversion efficiency of the photovoltaic module. At the same time, compared with the bus bar 14 being arranged at the end of the photovoltaic module, arranging the bus bar 14 on the solar cell 11 is beneficial to reducing the occupied space of the photovoltaic module.

[0044] It should be noted that the solar cell 11 in the present application can be a whole solar cell or a segmented solar cell. Among them, the segmented solar cell 11 can be a half-cell, a third-cell, a quarter-cell, an eighth-cell, etc.

[0045] In addition, two adjacent solar cells 11 can be arranged overlapping each other, that is, multiple solar cells 11 in the photovoltaic module can adopt the stack welding technology (i.e., the TR technology) to form a battery string. The distance between the overlapping parts at the ends of two adjacent solar cells 11, removing the gap between the solar cells 11, that is, the solar cells of the module only have a series spacing, which is beneficial to improving the output efficiency of the module. In other embodiments, a conventional welding method can also be used to form a photovoltaic module with a series spacing and a cell spacing, which is convenient for production.

[0046] The types of the cell 11 in this application include but are not limited to back contact cells (Back Contact, BC), tunnel oxide passivated contact cells (Tunnel Oxide Passivated Contact, TOPCon), heterojunction cells (Heterojunction with Intrinsic Thin-layer, HIT), passivated emitter and rear cells (Passivated Emitter and Rear Cell, PERC), or perovskite cells, etc. Optionally, the cell 11 can be a back contact cell. For a back contact cell (Back Contact, BC), the emitter, surface field, and metal electrodes of the BC cell are all arranged on the back of the cell and are cross-indicated and distributed. The front of the cell uses a SiNx / SiOx double-layer antireflection passivation film, so that there is no metal electrode occlusion on the front of the cell, enabling the cell to receive more incident light, reducing optical losses, and improving the photoelectric conversion efficiency. When the cell 11 is a back contact cell, at least a part of the bus bar 14 located on the back of the back contact cell is arranged out of alignment with at least a part of the pad 12 (pad point) in the first direction X, so that the position where the at least a part of the pad 12 (pad point) is welded to the solder strip 13 is far from the position where the solder strip 13 is welded to the corresponding at least a part of the bus bar 14, avoiding the risk of false soldering at the position where the at least a part of the pad 12 (pad point) is welded to the solder strip 13, and improving the structural stability of the back contact cell.

[0047] In other embodiments, the cell 11 provided by the present application may also be a Tunnel Oxide Passivated Contact (TOPCon) cell. The Tunnel Oxide Passivated Contact cell sequentially includes a metallic silver electrode, a front surface silicon nitride passivation layer, a boron-doped emitter, an N-type substrate silicon layer, a diffusion doping layer, an ultra-thin silicon oxide, a doped polysilicon, silicon nitride, and a metallic silver electrode along its thickness direction. The back surface of the cell is composed of an ultra-thin silicon oxide (1 nm - 2 nm) and a phosphorus-doped microcrystalline amorphous hybrid Si thin film, and the two together form a passivated contact structure, so that the solder tape and the bus bar can also be arranged on the back surface of the cell 11. This structure can block the recombination of minority carriers (holes), improving the open-circuit voltage and short-circuit current of the cell. The ultra-thin oxide layer allows majority carriers (electrons) to tunnel into the polysilicon layer while blocking the recombination of minority carriers (holes). The good passivation effect of the ultra-thin silicon oxide and the heavily doped silicon thin film causes the energy band on the silicon wafer surface to bend, thereby forming a field passivation effect, greatly increasing the probability of electron tunneling, reducing the contact resistance, improving the open-circuit voltage and short-circuit current of the cell, and thus improving the conversion efficiency of the cell. When the cell 11 is a Tunnel Oxide Passivated Contact cell, at least a part of the bus bar 14 located on the back surface of the Tunnel Oxide Passivated Contact cell and at least a part of the pad 12 (pad point) are arranged offset in the first direction X, so that the position where the at least a part of the pad 12 (pad point) is welded to the solder tape 13 is far from the position where the solder tape 13 is welded to the corresponding at least a part of the bus bar 14, avoiding the risk of virtual soldering at the position where the at least a part of the pad 12 (pad point) is welded to the solder tape 13, and improving the structural stability of the Tunnel Oxide Passivated Contact cell.

[0048] In other embodiments, the cell 11 provided by the present application may also be a Heterojunction with Intrinsic Thin-layer (HIT) cell. Along its thickness direction, the HIT cell sequentially includes a front surface low-temperature silver electrode, a front surface conductive thin film, an N-type amorphous silicon thin film, an intrinsic amorphous silicon thin film, an N-type substrate silicon layer, an intrinsic amorphous silicon thin film, a P-type amorphous silicon thin film, a back surface conductive thin film, and a back surface low-temperature silver electrode.

[0049] In other embodiments, the cell 11 provided by the present application may also be a Passivated Emitter and Rear Cell (PERC). Along its thickness direction, the PERC cell sequentially includes a front surface metallic silver electrode, a front surface silicon nitride passivation layer, a phosphorus layer emitter, a P-type substrate silicon layer, a local aluminum back surface field, a metallic aluminum back electrode, and a back passivation layer (Al2O3 / SiNx). The PERC cell uses a passivation film to passivate the back surface, replacing the full aluminum back surface field, enhancing the internal back reflection of light on the silicon substrate, reducing the recombination rate of the back surface, and improving the efficiency of the cell by 0.5% - 1%.

[0050] In other embodiments, the battery cell 11 provided in the present application may also be a perovskite battery. Along its thickness direction, the perovskite battery sequentially includes a substrate material, a conductive thin film, an electron transport layer (titanium dioxide), a perovskite absorption layer (hole transport layer), and a metal cathode. The perovskite material has a high light absorption coefficient and a long carrier diffusion distance. After the photons absorbed by the perovskite material are converted into electrons, they can be easily collected by the electrodes with less loss. Therefore, a high photo-generated voltage and current can be generated, making the perovskite exhibit a high photoelectric conversion efficiency.

[0051] The following takes the battery cell 11 selected as a back-contact battery as an example for detailed description.

[0052] In a possible implementation manner, as Figure 2 shown, the battery cell 11 at least includes a first region, and the bus bar 14 and the pad 12 (pad point) in the first region are arranged in a dislocation along the first direction X.

[0053] When the battery cell 11 is a back-contact battery, along the first direction X, the pads 12 (pad points) closest to both sides of the bus bar 14 have a first distance D1, satisfying 13 mm ≤ D1 ≤ 15 mm. In some embodiments, the first distance D1 may be 13 mm, 13.1 mm, 13.2 mm, 13.3 mm, 13.4 mm, 13.5 mm, 13.6 mm, 13.7 mm, 13.8 mm, 13.9 mm, 14 mm, 14.1 mm, 14.2 mm, 14.3 mm, 14.4 mm, 14.5 mm, 14.6 mm, 14.7 mm, 14.8 mm, 14.9 mm, 15 mm.

[0054] Along the first direction X, the size of the bus bar 14 is d, satisfying 8 mm < d < 13 mm. In some embodiments, d may be 8.5 mm, 8.6 mm, 8.8 mm, 9 mm, 9.2 mm, 9.4 mm, 9.5 mm, 9.6 mm, 9.8 mm, 10 mm, 10.2 mm, 10.4 mm, 10.5 mm, 10.6 mm, 10.8 mm, 11 mm, 11.2 mm, 11.4 mm, 11.5 mm, 11.6 mm, 11.8 mm, 12 mm, 12.2 mm, 12.4 mm, 12.5 mm, etc.

[0055] Therefore, along the first direction X, the first distance D1 should be at least greater than the size d of the bus bar 14, so that at least a part of the bus bar 14 is misaligned with at least a part of the pad 12 (pad point) along the first direction X, reducing the risk of poor soldering at the connection between the pad 12 (pad point) and the solder strip 13, and improving the stability and firmness of the connection between the pad 12 (pad point) and the solder strip 13, thereby enabling the photovoltaic module to have good structural stability and good power transmission efficiency.

[0056] When 13mm ≤ D1 ≤ 15mm is satisfied, the distance between the pads 12 (pad points) closest to both sides of the bus bar 14 is moderate, that is, the current transmission distance within the area between the pads 12 (pad points) closest to both sides of the bus bar 14 is moderate, reducing the risk of power waste, which is beneficial to improving the photoelectric conversion efficiency of the photovoltaic module. At the same time, it improves the stability and firmness of the area where the solder strip 13 is welded to the pads 12 (pad points) closest to both sides of the bus bar 14 fixed on the back of the photovoltaic module, and reduces the risk of the solder strip 13 detaching from the battery cell 11 when the photovoltaic module is subjected to external forces.

[0057] When 8mm < d < 13mm is satisfied, the width of the bus bar 14 is moderate, enabling the bus bar 14 to have good current-carrying capacity, improving the mechanical strength of the bus bar 14, facilitating installation, reducing the risk of the battery cell 11 having hidden cracks, and at the same time enabling the bus bar 14 to have good heat dissipation capacity and good electrical conductivity, which is beneficial to further improving the photoelectric conversion efficiency of the photovoltaic module.

[0058] In a possible implementation manner, as Figure 2 shown, along the first direction X, there is a second distance D2 between adjacent pads 12 (pad points) on the same side of the bus bar 14, satisfying 5mm < D2 < 10mm. In some embodiments, the second distance D2 can be 5.5mm, 5.6mm, 5.8mm, 6mm, 6.2mm, 6.4mm, 6.5mm, 6.6mm, 6.8mm, 7mm, 7.2mm, 7.4mm, 7.5mm, 7.6mm, 7.8mm, 8mm, 8.2mm, 8.4mm, 8.5mm, 8.6mm, 8.8mm, 9mm, 9.2mm, 9.4mm, 9.5mm, etc.

[0059] When 5mm < D2 < 10mm is satisfied, the distance between adjacent pads 12 (pad points) on the same side of the bus bar 14 is made appropriate, that is, the current transmission distance within the area between adjacent pads 12 (pad points) on the same side of the bus bar 14 is made appropriate, reducing the risk of power waste, being beneficial to improving the photoelectric conversion efficiency of the photovoltaic module, and at the same time avoiding the distance between adjacent pads 12 (pad points) on the same side of the bus bar 14 being too close, that is, avoiding the excessive number of pads 12 (pad points), reducing the risk of short circuit caused by solder overflow, being beneficial to reducing the consumption of silver paste, improving the working stability and use safety of the photovoltaic module, and being beneficial to reducing production costs.

[0060] In a possible implementation manner, since the positions of the solder tape 13 and the bus bar 14 are set according to actual requirements, for the convenience of production, a second region as shown in Figure 4 may also be provided on the battery cell 11, and the bus bar 14 in the second region and at least part of the pads 12 (pad points) are arranged to at least partially overlap in the first direction X, that is, the projections of the bus bar 14 and at least part of the pads 12 (pad points) in the second region in the thickness direction of the photovoltaic module at least partially structurally coincide.

[0061] In a possible implementation manner, as shown in Figure 5 a conductive adhesive 15 is provided at at least part of the positions in the second region, and the conductive adhesive 15 is used for electrically connecting the pads 12 (pad points) and the solder tape 13.

[0062] In this embodiment, the conductive adhesive 15 has good heat insulation performance and electrical conductivity, and the conductive adhesive 15 should be provided at least at the position where the bus bar 14 and at least part of the pads 12 (pad points) at least partially overlap in the first direction X. Therefore, compared with the soldering of the solder tape 13 and the pads 12 (pad points) with solder, setting the conductive adhesive 15 on the pads 12 (pad points) at this position can avoid the risk of virtual soldering caused by heat transfer after the solder melts, improve the stability and reliability of the connection between the battery cell 11 and the solder tape 13, enable the production process of planning the positions of the pads 12 (pad points) not to be increased when installing the pads 12 (pad points), avoid the problem of unstable connection at the welding place of the pads 12 (pad points) and the solder tape 13, improve production efficiency, and be beneficial to improving the stability and firmness of the connection between the pads 12 (pad points) and the solder tape 13, so that the photovoltaic module has good structural stability and good electrical energy transmission efficiency. At the same time, in this example, the pads 12 (pad points) and the solder tape 13 are connected by the conductive adhesive 15, which is convenient for the battery cell 11 to set the position of the bus bar 14 according to actual requirements.

[0063] Among them, when the cell 11 is a tunnel oxide passivated contact cell, that is, the cell 11 can also include a first region, or a first region and a second region. The pads 12 and the solder tapes 13 in the first region are welded by solder, and the pads 12 and the solder tapes 13 in the second region are connected by a conductive adhesive 15, which can avoid the problem of unstable connection at the welding point of the pads 12 (pad points) and the solder tapes 13, and improve the production efficiency and structural stability.

[0064] In addition, when the cell 11 is a back contact cell, as Figure 3 shown, for the convenience of production, a plurality of pads 12 (pad points) are arranged at equal intervals on the back of the cell 11, which can realize one-step installation of the tooling. At the same time, according to the position of the preset bus bar 14, along the first direction X, solder is provided on the pads 12 (pad points) corresponding to the misaligned positions of the pads 12 (pad points) and the bus bar 14, and a conductive adhesive 15 is provided on the pads 12 (pad points) corresponding to the non-misaligned positions of the pads 12 (pad points) and the bus bar 14. Then, the solder tape 13 is fixed on the cell 11 through the solder and the conductive adhesive 15, and then the bus bar 14 is welded on the solder tape 13, and thus a battery string 1 as Figure 3 shown can be formed.

[0065] Alternatively, in other embodiments, when the battery cell 11 is a back contact battery, the pads 12 (pad points) can be installed on the battery cell 11 at preset equal intervals, so that the tooling can be installed in place in one step. Then, according to the actual position of the preset bus bar 14, along the first direction X, it is determined that the position where the pad 12 (pad point) on the battery cell 11 overlaps with the bus bar 14 is preset, that is, the pad 12 (pad point) at this location can be a movable pad 12 (pad point), and the movable pad 12 (pad point) can be moved upward or downward along the first direction X so that the movable pad 12 (pad point) is moved to one side of the bus bar 14, that is, the movable pad 12 (pad point) is now ad point) is the pad 12 (pad point) closest to the bus bar 14, and at the same time, it is necessary to ensure that the distance between the movable pad 12 (pad point) and the pad 12 (pad point) on the other side of the bus bar 14 meets the value of the above-mentioned first distance D1, and then after the movable pad 12 (pad point) is moved into place, even if all the pads 12 (pad points) on the battery cell 11 are misaligned with the bus bar 14 along the first direction X, solder is then applied to all the pads 12 (pad points) through welding equipment, and then all the pads 12 (pad points) are welded to the welding strip 13 through solder, and then the bus bar 14 is directly welded to the welding strip 13. Since the number of bus bars 14 arranged in the photovoltaic module is generally three, and the three bus bars 14 are generally the positive bus bar 14, the negative bus bar 14 and the middle bus bar 14, the number of pads 12 (pad points) overlapping with the bus bars 14 along the first direction X on the battery cell 11 is relatively small, that is, the number of the above-mentioned movable pads 12 (pad points) is relatively small, and the problem of cold soldering can be avoided by moving the positions of a few pads 12 (pad points) during the production process. Therefore, the process for preparing the photovoltaic module in this embodiment is simple and feasible, convenient for actual production, and can improve production efficiency.

[0066] For example, when the battery cell 11 is a back contact battery, Figure 3 The movable pad 12 (pad point) at the overlapping position of the bus bar 14 along the first direction X in the battery cell 11 shown in the figure is moved upward by a certain distance along the first direction X, so that the movable pad 12 (pad point) is staggered with the bus bar 14 along the first direction X, thereby forming the following Figure 1 The battery string 1 is shown.

[0067] Or, in other embodiments, Figure 1As shown, when the solar cell 11 is a back-contact solar cell, all the pads 12 (pad points) and all the busbars 14 in the solar cell 11 can be arranged with a dislocation along the first direction X. During the production process, solder is provided on the pads 12 (pad points), so that the solder tape 13 can be welded to the pads 12 (pad points). Specifically, first, the position of the busbar 14 is preset, and then, according to the position of the busbar 14, the installation position of the pads 12 (pad points) on the solar cell 11 is preset, so that all the pads 12 (pad points) are arranged with a dislocation along the first direction X relative to the busbar 14. Then, the pads 12 (pad points) installed according to the preset position are installed on the back of the solar cell 11. Further, solder is coated on all the pads 12 (pad points) through a welding device, and then all the pads 12 (pad points) are welded to the solder tape 13 through the solder. Then, the busbar 14 is directly welded to the solder tape 13, and a solar cell string 1 as shown in Figure 1 is formed.

[0068] Among them, when the solar cell 11 is a tunnel oxide passivated contact solar cell, all the pads 12 (pad points) and all the busbars 14 on the back of the solar cell 11 can be arranged with a dislocation along the first direction X, or, part of the pads 12 (pad points) and busbars 14 on the back of the solar cell 11 are arranged with a dislocation along the first direction X, and the other part of the pads 12 (pad points) and busbars 14 are not arranged with a dislocation along the first direction X, which can be selected according to actual needs. In addition, the gap between the pads 12 (pad points) and the gap between the two pads 12 (pad points) closest to the busbar 14 can be set according to actual needs.

[0069] In a possible implementation manner, as shown in Figure 5 , along the second direction Y, the size of the conductive adhesive 15 is L, satisfying 0.3 mm < L < 1 mm. In some embodiments, L can be 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, etc.

[0070] When 0.3 mm < L < 1 mm is satisfied, the width of the conductive adhesive 15 is appropriate, that is, the area of the connection between the solder tape 13 and the pads 12 (pad points) is appropriate, which is beneficial to improving the firmness and stability of the connection between the solder tape 13 and the pads 12 (pad points) through the conductive adhesive 15, avoiding the too narrow width of the conductive adhesive 15, avoiding the risk of unqualified tensile force of the conductive adhesive 15, that is, avoiding the risk that the bonding strength of the conductive adhesive 15 fails to meet the expected or specified requirements, and reducing the risk of increasing the resistance of the conductive adhesive 15. At the same time, the risk of overflow of the conductive adhesive 15 after being extruded by the solder tape 13 and the pads 12 (pad points) is reduced, and further the risk of short circuit of the photovoltaic module is reduced, and the reliability and safety of the operation of the photovoltaic module are improved.

[0071] In a possible implementation, as Figure 5 shown, along the thickness direction of the cell 11, the thickness of the conductive adhesive 15 is H, satisfying 20um < H < 180um. In some embodiments, H can be 25um, 30um, 35um, 40um, 45um, 50um, 55um, 60um, 65um, 70um, 75um, 80um, 85um, 90um, 95um, 100um, 105um, 110um, 115um, 120um, 125um, 130um, 135um, 140um, 145um, 150um, 155um, 160um, 165um, 170um, 175um, etc.

[0072] When 20um < H < 180um is satisfied, the thickness of the conductive adhesive 15 is moderate, which is beneficial to improving the firmness and stability of the connection between the solder strip 13 and the pad 12 (pad point) through the conductive adhesive 15, avoiding too small a thickness of the conductive adhesive 15, avoiding the risk of unqualified tensile force of the conductive adhesive 15, that is, avoiding the risk that the bonding strength of the conductive adhesive 15 fails to meet the expected or specified requirements. At the same time, it is beneficial to improve the structural strength of the battery at the position where the conductive adhesive 15 is provided, avoiding the risk of increasing the thickness of the glue film of the photovoltaic module, and further avoiding the risk of increasing the thickness of the photovoltaic module, which is beneficial to reducing the occupied space of the photovoltaic module.

[0073] In a possible implementation, as Figure 5 shown, the material of the conductive adhesive 15 is a mixture of silver and resin.

[0074] In this embodiment, most of the materials in the conductive adhesive 15 are conductive particles, such as any one or more of silver, copper, nickel, aluminum, zinc, iron, carbon powder, etc., so that the conductive adhesive 15 has good electrical conductivity. A small part of the materials in the conductive adhesive are resins, such as any one or more of epoxy resin, polyurethane, acrylic resin, chloroprene rubber, etc., so that the conductive adhesive 15 has certain viscosity and heat insulation performance, so that the conductive adhesive 15 does not decompose under the heat generated during the welding of the bus bar 14 and the solder strip 13, improving the connection reliability and stability of the conductive adhesive 15 for connecting the pad 12 (pad point) and the solder strip 13, thereby enabling the photovoltaic module to have good structural stability and good power transmission efficiency.

[0075] In a possible implementation, as Figure 6As shown, along the second direction Y, the size of the solder strip 13 is M, where 0.3 mm < M < 1 mm, and the size of the solder pad 12 (pad point) is N, where 0.3 mm < N < 1.2 mm. In some embodiments, M can be 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, etc. N can be 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, 1.1 mm, etc.

[0076] When 0.3 mm < M < 1 mm and 0.3 mm < N < 1.2 mm are satisfied, the sizes of both the solder strip 13 and the solder pad 12 (pad point) are appropriate, that is, the sizes of the solder strip 13 and the solder pad 12 (pad point) match each other, avoiding the risk of short - circuit caused by the overflow of solder or conductive adhesive 15 due to the solder strip 13 being too narrow relative to the solder pad 12 (pad point), improving the use safety of the photovoltaic module. At the same time, the connection area between the solder strip 13 and the solder pad 12 (pad point) is appropriate, improving the stability and reliability of the connection of the solder strip 13 to the back of the cell 11 through the solder pad 12 (pad point). In addition, the matching of the sizes of the solder strip 13 and the solder pad 12 (pad point) is beneficial to reducing the loss and interference during signal transmission, and can further improve the photoelectric conversion efficiency of the photovoltaic module.

[0077] When 0.3 mm < M < 1 mm is satisfied, it is convenient to weld the solder strip 13 onto the solder pad 12 (pad point), reducing the risk of the solder strip 13 breaking, improving the convenience of the welding operation. At the same time, the resistance of the solder strip 13 is appropriate, avoiding heat accumulation, which is beneficial to improving the convenience of photovoltaic module production and the working safety.

[0078] When 0.3 mm < N < 1.2 mm is satisfied, the solder pad 12 (pad point) has good mechanical strength, reducing the risk of the cell 11 breaking or electrical components such as the solder strip 13 becoming desoldered when the photovoltaic module is subjected to external forces, improving the structural stability and use safety of the photovoltaic module. At the same time, it is beneficial to the heat dissipation of the photovoltaic module.

[0079] In some possible embodiments, the photovoltaic module may further include a frame, a backsheet, photovoltaic glass, and encapsulant film. The frame is used to install the photovoltaic module at the desired installation location. The encapsulant film is disposed and filled between the front and back surfaces of the cell 11, between the photovoltaic glass, adjacent cells 11, etc. The encapsulant film may be a transparent colloid with good light transmittance and anti-aging properties. For example, the encapsulant film may be an Ethylene-Vinyl Acetate Copolymer (EVA) film or a Polyolefin Elastomer (POE) film, which can be selected according to actual needs.

[0080] In addition, the photovoltaic glass covers the encapsulant film on the front surface of the cell 11. The photovoltaic glass can be ultra-clear glass, which has good high light transmittance, high transparency, and at the same time has good physical properties, mechanical properties, and optical properties. At the same time, the encapsulant film has a certain viscosity. The encapsulant film is used to connect the photovoltaic glass and the cell 11, and the encapsulant film has a certain sealing effect on the cell 11, making the cell 11 sealed and insulated, so that the cell 11 has the functions of waterproofing and moisture-proofing.

[0081] The above are only the specific embodiments of the embodiments of the present application, but the protection scope of the embodiments of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of the present application should be covered by the protection scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application shall be subject to the protection scope of the claims.

Claims

1. A photovoltaic module, characterized in that: The photovoltaic module includes a bus bar (14) and at least two cell strings (1). The bus bar (14) is used to electrically connect the cell strings (1). The cell string (1) includes a solder ribbon (13) and at least two solar cells (11). Along a first direction (X), at least two spaced-apart pads (12) are provided on the back surface of the solar cell (11). The pads (12) are used to weld the solder ribbon (13) to the solar cell (11). Along the thickness direction of the solar cell (11), the surface of the solder ribbon (13) facing away from the pad (12) is directly welded to the bus bar (14). At least part of the bus bar (14) and at least part of the pads (12) are arranged in a staggered manner along the first direction (X).

2. The photovoltaic module according to claim 1, characterized in that: The solar cell (11) includes at least a first region, and in the first region, the bus bar (14) and the pads (12) are arranged in a staggered manner along the first direction (X). When the solar cell (11) is a back-contact solar cell, along the first direction (X), the pads (12) closest to both sides of the bus bar (14) have a first distance D1, satisfying 13 mm ≤ D1 ≤ 15 mm. Along the first direction (X), the size of the bus bar (14) is d, satisfying 8 mm < d < 13 mm.

3. The photovoltaic module according to claim 2, characterized in that: Along the first direction (X), there is a second distance D2 between adjacent pads (12) on the same side of the bus bar (14), satisfying 5 mm < D2 < 10 mm.

4. The photovoltaic module according to claim 1, characterized in that: The solar cell (11) further includes a second region, and in the second region, the bus bar (14) and at least part of the pads (12) are arranged at least partially overlapping along the first direction (X).

5. The photovoltaic module according to claim 4, characterized in that: A conductive adhesive (15) is provided at at least part of the positions in the second region. The conductive adhesive (15) is used to electrically connect the pad (12) and the solder ribbon (13).

6. The photovoltaic module according to claim 5, characterized in that: Along a second direction (Y), the size of the conductive adhesive (15) is L, satisfying 0.3 mm < L < 1 mm.

7. The photovoltaic module according to claim 5, characterized in that: Along the thickness direction of the solar cell (11), the thickness of the conductive adhesive (15) is H, satisfying 20 μm < H < 180 μm.

8. The photovoltaic module according to claim 5, characterized in that: The material of the conductive adhesive (15) is a mixture of silver and resin.

9. The photovoltaic module according to any one of claims 1 to 8, characterized in that: Along the second direction (Y), the size of the solder ribbon (13) is M, satisfying 0.3 mm < M < 1 mm, and the size of the pad (12) is N, satisfying 0.3 mm < N < 1.2 mm.

10. The photovoltaic module according to any one of claims 1 to 8, characterized in that: The solar cell (11) is a whole-piece solar cell or a segmented solar cell, and / or two adjacent solar cells (11) overlap each other.

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