A photovoltaic module

Abstract

The present application provides a photovoltaic module, including: a cell, a conductor and a conductive backplane. The cell includes a cell body and an electrode arranged on the cell body. The conductive backplane includes an insulating layer, a conductive layer and a back adhesive film stacked in sequence, wherein the insulating layer has a plurality of through holes penetrating the insulating layer. A plurality of conductors are arranged in an array between the cell and the conductive backplane, and the conductors are electrically interconnected with the electrodes and the conductive layer through the through holes on the insulating layer. When the local temperature of the cell reaches the melting point of the conductor, the conductor corresponding to the local part of the cell melts, disconnecting the local part of the cell from the circuit, preventing the local part of the cell from continuing to heat up, and thereby preventing the adverse effects of local overheating on the photovoltaic module. In addition, the other parts of the cell except for the local part can still continue to generate electricity, ensuring the photoelectric conversion efficiency of the photovoltaic module.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular, to a photovoltaic module with a conductive backplane. Background Art

[0002] Photovoltaic modules are devices that convert solar energy into electrical energy. They are usually made up of multiple cells connected in series or parallel. Photovoltaic modules are generally exposed to the outdoors for a long time, so their surfaces are easily obscured by dust, fallen leaves and other obstructions. In the series branch of a photovoltaic module, the obscured cell will become a resistor, consuming the energy generated by other normal cells with light, resulting in a local temperature rise on the cell. This phenomenon is called the hot spot effect. The high temperature generated by the hot spot effect will accelerate the aging process of photovoltaic modules, reduce the power generation efficiency of photovoltaic modules, and even cause them to fail completely. More seriously, it may cause photovoltaic modules to spontaneously combust, leading to safety accidents such as fires.

[0003] Therefore, how to provide a technical solution to the above-mentioned technical problems is an urgent problem that technicians in this field need to solve. Summary of the invention

[0004] The present application provides a photovoltaic module resistant to hot spot effect, which avoids excessive local temperature of the battery cell by fusing the conductor, thereby avoiding a series of adverse effects caused by it.

[0005] Specifically, according to the first aspect of the present application, a photovoltaic module is provided, comprising: a battery cell, a conductor and a conductive backplane, the battery cell comprising a battery body and an electrode arranged on the battery body; the conductive backplane comprises an insulating layer, a conductive layer and a back adhesive film stacked in sequence, wherein the insulating layer has a plurality of through holes penetrating the insulating layer; a plurality of conductors are arranged in an array between the battery cell and the conductive backplane, the conductors are electrically interconnected with the electrodes and the conductive layer through the through holes on the insulating layer, and when the local temperature of the battery cell reaches the melting point of the conductor, the conductor corresponding to the local part of the battery cell melts.

[0006] In some embodiments, a plurality of electrical conductors are disposed in one through-hole.

[0007] In some embodiments, an electrical conductor is disposed in a through hole.

[0008] In some embodiments, the ratio of the volume of the conductor to the volume of the through hole is greater than or equal to 25% and less than or equal to 45%.

[0009] In some embodiments, the ratio of the volume of the conductor to the volume of the through hole is greater than or equal to 30% and less than or equal to 40%.

[0010] In some embodiments, the electrode is a combination of one or more of a main grid line, a thin grid line, a PAD dot, or a grid line thickening segment.

[0011] In some embodiments, the area of ​​the first cross-section of the conductor in contact with the electrode is S1, the area of ​​the second cross-section of the conductor in contact with the conductive layer is S2, the first cross-section and the second cross-section are arranged on opposite sides of the conductor, and the area of ​​the third cross-section between the first cross-section and the second cross-section corresponding to the narrowest point in the longitudinal section of the conductor is S3, and: S1>S3, and / or S2>S3.

[0012] In some embodiments, the thickness of the intermetallic compound layer at the interface between the conductor and the electrode is greater than or equal to 0.5 μm and less than or equal to 3 μm, and / or the thickness of the intermetallic compound layer at the interface between the conductor and the conductive layer is greater than or equal to 0.5 μm and less than or equal to 3 μm.

[0013] In some embodiments, in a longitudinal section of the electrical conductor, a base angle is greater than or equal to 25° and less than or equal to 85°.

[0014] In some embodiments, in a longitudinal section of the electrical conductor, a base angle is greater than or equal to 60° and less than or equal to 70°.

[0015] In some embodiments, the conductor is a column-like structure, which includes a cylindrical-like structure and an elliptical-column-like structure.

[0016] In some embodiments, the material of the electrical conductor is an alloy containing tin and bismuth.

[0017] In some embodiments, the melting point of the electrical conductor is greater than or equal to 140°C and less than or equal to 160°C.

[0018] In some embodiments, the melting point of the electrical conductor is greater than or equal to 145°C and less than or equal to 155°C.

[0019] In some embodiments, the specific heat capacity of the electrical conductor is greater than or equal to 150 J / (kg·K) and less than or equal to 250 J / (kg·K).

[0020] The positive effects of this application are:

[0021] During operation, if the photovoltaic module of the present application is blocked by obstructions such as fallen leaves, causing the local temperature of the cell to rise, the conductor corresponding to the local cell will fuse when its temperature reaches its melting point, causing the local cell connected to the conductor to be disconnected from the circuit, thereby reducing the local temperature of the cell, thereby preventing the local temperature from exceeding a certain limit, which may cause permanent damage such as partial burning of the photovoltaic module, formation of dark spots, aging of packaging materials, and even cause safety hazards. In addition, in the photovoltaic module of the present application, only part of the cell is disconnected from the circuit, and the other parts of the cell except this part can still continue to generate electricity, so the impact on the photoelectric conversion efficiency of the photovoltaic module is relatively small. The photovoltaic module of the present application not only has a self-protection function against heat spots, but also can maintain a high photoelectric conversion efficiency even if it is blocked by obstructions such as fallen leaves. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of the various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in understanding, but these details are to be regarded as exemplary only. Therefore, it will be appreciated by those of ordinary skill in the art that various changes and modifications may be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and structures may be omitted for clarity and conciseness.

[0023] Figure 1 Schematic diagrams of the structures of photovoltaic modules according to some embodiments are shown.

[0024] Figure 2 A schematic diagram of a conductive backplane according to some embodiments is shown.

[0025] Figure 3 Shows Figure 2 A partial enlarged view of the conductive backplane.

[0026] Figure 4 Schematic diagrams of the structures of battery cells according to some embodiments are shown.

[0027] Figure 5 Schematic diagram showing electrical conductors on a cell sheet according to some embodiments.

[0028] Figure 6 A schematic longitudinal cross-sectional view of an electrical conductor according to some embodiments is shown.

[0029] Among them, 100 represents the photovoltaic module, 1 represents the cover plate, 2 represents the front film, 3 represents the battery cell, 31 represents the electrode, 32 represents the battery body, 4 represents the conductive back plate, 41 represents the insulating layer, 42 represents the conductive layer, 43 represents the back film, 44 represents the through hole, 45 represents the conductor, 451 represents the first side in the longitudinal section of the conductor, 452 represents the second side in the longitudinal section of the conductor, 453 represents the third side in the longitudinal section of the conductor, and 454 represents the bottom angle in the longitudinal section of the conductor. DETAILED DESCRIPTION

[0030] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0031] The term "first" or "second" in the specification and claims of this application may include one or more of the features explicitly or implicitly. In the description of this application, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the objects connected before and after are in an "or" relationship.

[0032] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0033] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0034] Figure 1 FIG. 1 shows a schematic structural diagram of a photovoltaic assembly 100 according to some embodiments of the present application. Figure 1 It can be seen that the photovoltaic module 100 includes a cover plate 1, a front adhesive film 2, a battery cell 3, and a conductive back plate 4 stacked in sequence. The present application does not further limit the materials of the cover plate 1 and the front adhesive film 2, and those skilled in the art can select them as needed. For example, the cover plate 1 is usually transparent, and it can be a transparent polymer film, such as an ethylene-tetrafluoroethylene copolymer film, or a transparent glass, such as ultra-white photovoltaic glass. The material of the front adhesive film 2 can be selected from ethylene-octene copolymer (POE), ethylene-vinyl acetate copolymer (EVA), etc.

[0035] Since the present application adopts a conductive back plate 4, it can be adapted to a battery cell 3 with a higher front power generation efficiency, such as a back contact (BC) battery cell 3. The back contact battery cell 3 includes: a traditional IBC battery cell 3 (interdigitated back contact battery), a TBC battery cell 3 (TOPCon back contact battery), an HBC battery cell 3 (heterojunction back contact battery) or a hybrid back contact battery cell 3 (that is, the PN passivation therein is a different passivation material, for example, it can be a combination of polycrystalline silicon passivation and amorphous / microcrystalline passivation).

[0036] refer to Figure 4 In the back contact cell 3, the cell body 32 at least includes a substrate and a doping layer on the substrate.

[0037] For the IBC cell 3, its cell body 32 includes a first doped semiconductor part and a second doped semiconductor part arranged alternately and spaced along a first direction on the substrate to form a finger-shaped doped part structure. One of the first doped semiconductor part and the second doped semiconductor part is n-type doped, and the other is p-type doped, and the first doped semiconductor part and the second doped semiconductor part are respectively provided with spaced electrode 31 structures.

[0038] For the TBC cell 3, its cell body 32 includes a tunneling oxide layer disposed on a substrate, and a first doped semiconductor portion and a second doped semiconductor portion formed by a doped polysilicon layer. The TOPCon structure formed by the stacked tunneling oxide layer and the doped polysilicon layer can provide a higher carrier lifetime and lower surface recombination for the TBC cell 3 than the IBC cell 3, which is beneficial to improving the photoelectric conversion efficiency of the TBC cell 3.

[0039] For the HBC cell 3, its cell body 32 includes an n-type doping layer and a p-type doping layer stacked on a substrate to form a heterojunction structure. Among them, the n-type doping layer includes but is not limited to microcrystalline silicon or amorphous silicon (to provide electrons), and the p-type doping layer can also use microcrystalline silicon or amorphous silicon (such as using boron as a dopant to provide holes). The HBC cell 3 helps to improve the carrier lifetime and reduce surface recombination. Furthermore, a conductive oxide layer (i.e., TCO) can be set between the surface of the n-type doping layer and the p-type doping layer and the electrode 31, which is beneficial to collect carriers in the doping area and can also play a certain anti-reflection role.

[0040] For the hybrid back contact cell 3, its cell body 32 can adopt a layer structure similar to that of the IBC cell 3 or the TBC cell 3, and configure a corresponding passivation layer structure thereon, such as a combination of at least two of polycrystalline silicon passivation, amorphous silicon passivation and microcrystalline silicon passivation.

[0041] Any of the above-mentioned back-contact cells 3 can be used as the cell 3 in the photovoltaic module 100 of the present application.

[0042] Continue to refer Figure 1 The conductive backplane 4 includes an insulating layer 41, a conductive layer 42 and a back adhesive film 43 stacked in sequence. The insulating layer 41 has a plurality of through holes 44 penetrating the insulating layer 41. The conductor 45 is arranged in the through hole 44. The electrode 31 on the battery body 32 is electrically interconnected with the conductive layer 42 through the conductor 45. Among them, the insulating layer 41 is arranged on the side of the conductive backplane 4 close to the battery cell 3. The insulating layer 41 can be transparent or translucent, such as a foamed polyethylene (EPE) film. The conductive layer 42 below can be seen through the insulating layer 41. The conductive layer 42 can be selected from any combination of one or more of copper, aluminum, copper-aluminum alloy, and aluminum-nickel alloy. The back adhesive film 43 is arranged below the conductive layer 42. The material of the back adhesive film 43 can be selected from one or a combination of two of ethylene-octene copolymer (POE) and ethylene-vinyl acetate copolymer (EVA). In some embodiments, the conductive backplane 4 can also include an encapsulation backplane, which is arranged below the back adhesive film 43. The encapsulation backplane can be made of materials such as glass or organic polymer film.

[0043] Figure 2 A schematic diagram of through holes 44 in the insulating layer 41 on the conductive back plate 4 of the photovoltaic module 100 according to some embodiments of the present application is shown. It can be seen that the through holes 44 are arranged in the insulating layer 41 at intervals and arranged in an array. The conductors 45 are arranged in the through holes 44 and are also arranged in an array on the backlight surface of the battery cell 3. The conductive layer 42 is arranged on the side of the insulating layer 41 away from the battery cell 3, and the through holes 44 in the insulating layer 41 and the conductive layer 42 together enclose a space for accommodating the conductors 45.

[0044] Photovoltaic modules 100 are usually installed in open areas with plenty of sunshine. In long-term use, bird droppings, dust, fallen leaves and other obstructions are inevitable. Photovoltaic modules 100 are generally composed of multiple battery cells 3 connected in series or in parallel to obtain the desired voltage or current. Parallel bypass diodes are one of the conventional means to solve the hot spot effect, that is, a bypass diode is connected in parallel next to a string of batteries or multiple strings of batteries. Under normal circumstances, the bypass diode is not turned on and does not affect the normal operation of the photovoltaic module 100. When obstruction occurs, the bypass diode corresponding to the battery string where the obstructed battery cell 3 is located is turned on, and the string or strings of batteries connected in parallel with the bypass diode are short-circuited and removed from the circuit, which seriously affects the photoelectric conversion efficiency of the photovoltaic module 100.

[0045] According to research, the shape of the common battery cells 3 on the market is rectangular or square, with side lengths between 182-240 mm, and optional (182±2)×(191±2) mm², (182±2)×(210±2) mm², (210±2)×(210±2) mm². Therefore, in most cases where the hot spot effect occurs, the shielding only shields part of a battery cell 3, or parts of multiple battery cells 3. The part of the battery cell 3 is treated as a load, consuming the energy generated by other battery cells 3, resulting in local overheating. In the photovoltaic modules 100 of some embodiments of the present application, the local temperature of the cell 3 will increase due to factors such as the "hot spot effect", so that the temperature of the corresponding conductor 45 will also increase accordingly. The conductor 45 will melt when its temperature reaches its melting point. The melted conductor 45 flows under the action of gravity, and the conductor 45 will be disconnected at the melting point, that is, it will be blown, so that the cell 3 connected to the conductor 45 is partially disconnected from the circuit, so that the temperature of the local cell 3 can be reduced, avoiding the continuous rise of the local temperature of the cell 3, and then preventing the local overheating from having an adverse effect on the photovoltaic module 100. In addition, because the conductor 45 electrically connected only to the local cell 3 with the increased temperature is blown, the other parts of the cell 3 except the local part can still continue to generate electricity, so the power generation efficiency of the photovoltaic module 100 is less affected. The photovoltaic module 100 of the present application not only has the self-protection function of resistant to hot spots, but also can maintain a high photoelectric conversion efficiency even if it is blocked by obstructions such as fallen leaves.

[0046] The photovoltaic module 100 of the present application can be used in conjunction with conventional hot spot effect protection measures, which include: parallel bypass diodes, use of hot spot protection cells 3, etc.

[0047] One or more conductors 45 may be disposed in one through hole 44 . Figure 1The figure shows a case where one conductor 45 is disposed in one through hole 44. Different doping regions on the backlight surface of the back contact cell 3 are alternately distributed in sequence, and correspondingly, the electrodes 31 arranged on different doping regions are also alternately distributed and have different conductivity types. Only one conductor 45 is disposed in one through hole 44, and there is only one electrode 31 in the corresponding through hole 44. The opposite-sex electrode 31 adjacent to the electrode 31 can be insulated by the insulating layer 41, and it is no longer necessary to provide insulating glue on the adjacent opposite-sex electrode 31, which saves the process of applying insulating glue, shortens the process flow, and reduces costs.

[0048] A through hole 44 may also be provided with multiple conductors 45, such as 3-4 conductors 45. Multiple conductors 45 are provided in the same through hole 44, so that the number of through holes 44 on the insulating layer 41 can be reduced. Similarly, the through hole 44 needs to accommodate multiple conductors 45, and the volume of the through hole 44 is also larger. In the process of preparing the photovoltaic module 100, the through hole 44 needs to be aligned with the electrode 31 on the cell 3. A larger through hole 44 is easier to align with the electrode 31 on the cell 3, and the precision requirement for the process is lower, and the reliability of the prepared photovoltaic module 100 is better.

[0049] Figure 3 Shows Figure 2 A partial enlarged view of the insulating layer 41 of the photovoltaic module 100. It can be seen that the through hole 44 is a circular hole. Of course, the through hole 44 can also be other shapes such as a long hole, an elliptical hole, etc., which is not further limited in this application. In some embodiments, the through hole 44 is a circular hole, and its cross-section is a circle with a diameter of 4 to 8 mm, and optionally, the cross-section is a circle with a diameter of 5 to 6 mm. The thickness of the insulating layer 41 is 20 to 500 μm, and optionally, the thickness of the insulating layer 41 is 130-160 μm. The height of the conductor 45 in the photovoltaic module 100 is 130 μm-160 μm. The height of the conductor 45 varies with the thickness of the insulating layer 41, and the change trend is consistent. This application does not limit the height of the conductor 45, and it can be designed according to actual needs.

[0050] Continue to refer Figure 1 The battery cell 3 is arranged on a side of the insulating layer 41 away from the conductive layer 42. The battery cell 3 includes a battery body 32 and an electrode 31 arranged on the battery body 32. The electrode 31 on the battery body 32 and the conductive layer 42 are electrically interconnected through a conductor 45. The conductor 45 is formed by curing a conductive paste, such as solder paste or conductive glue. The conductive paste is pre-arranged on the electrode 31 of the battery cell 3 by printing, dispensing, etc., see Figure 5, or the conductive paste can be pre-set at the position corresponding to the conductive layer 42. Both of the above methods can improve production efficiency. It can also be set on the electrode 31 of the battery cell 3 or the corresponding position of the conductive layer 42 by printing, dispensing, etc. during the component manufacturing process, such as after the battery cell 3, the insulating layer 41, the conductive layer 42, and the back adhesive film 43 are laid out and before stacking, so as to reduce the process errors such as the layout deviation of the battery cell 3, the printing deviation of the electrode 31, the deviation of the insulating layer 41, and the deviation of the through hole 44 in the insulating layer 41 due to heat shrinkage or punching, which may cause the alignment deviation of the electrode 31 and the through hole 44 in the insulating layer 41. The conductor 45 is formed between the battery cell 32 and the conductive layer 42 by heating or infrared curing, so as to realize the electrical connection between the electrode 31 on the battery cell 3 and the conductive layer 42. The material of the conductor 45 can be selected from an alloy containing tin and bismuth, such as a tin-bismuth alloy, a tin-lead-bismuth alloy, a tin-bismuth-copper alloy, and a tin-bismuth-silver alloy.

[0051] Figure 1 The figure shows a situation where a conductor 45 is set in a through hole 44. It can be understood that in order to ensure that the conductor 45 flows and melts under the action of gravity after melting, the conductor 45 can be set to leave a certain gap between the corresponding through hole 44. In some embodiments, the ratio of the volume of the conductor 45 to the volume of the through hole 44 is controlled to be greater than or equal to 25% and less than or equal to 45%, for example, 25%, 30%, 35%, 40%, 45%. Table 1 shows the ratio of the volume of the conductor 45 to the volume of the through hole 44, corresponding to the melting of the conductor 45 after the battery cell 3 is partially blocked. The test results show that when the volume ratio of the conductor 45 to the volume of the through hole 44 is greater than 45%, the volume of the conductor 45 is too large compared to the volume of the through hole 44. The melted conductor 45 cannot be completely melted due to the limitation of the flow space. At this time, the conductor 45 still maintains the electrical connection, which will lead to the hot spot effect and the conductive back plate 4 is burned through. When the volume of the conductor 45 is less than 25% of the volume of the through hole 44, when the thickness of the insulating layer 41 is the same, that is, the height of the conductor 45 matches the thickness of the insulating layer 41, optionally, the height of the conductor 45 is equal to the thickness of the insulating layer 41, or the height of the conductor 45 is slightly greater than the thickness of the insulating layer 41. The conductor 45 will inevitably be thinner, and the thinner conductor 45 has a relatively large resistance, which reduces the efficiency of the photovoltaic module 100, and the conductor 45 is too small relative to the through hole 44, which may cause the conductor 45 to have abnormalities such as poor electrical connection after the photovoltaic module 100 is laminated. The ratio of the volume of the conductor 45 to the volume of the through hole 44 is controlled within a range of greater than or equal to 25% and less than or equal to 45%. When the temperature of the local area of ​​the battery cell 3 rises to the melting point of the conductor 45, the conductor 45 corresponding to the local area of ​​the battery cell 3 will be melted, ensuring that there is no abnormality in the conductive backplane 4.

[0052] Table 1

[0053]

[0054] It can be understood that when a plurality of conductors 45 are disposed in the through hole 44 , the plurality of conductors 45 are disposed at intervals, and a large gap exists between the conductor 45 and the through hole 44 . The melted conductor 45 has a large flow space, thereby causing the conductor 45 to fuse.

[0055] In some embodiments, the ratio of the volume of the conductor 45 to the volume of the through hole 44 is controlled within a range of 30%-40%. This not only ensures that the conductor 45 can be melted and blown, thus avoiding the hot spot effect, but also that the conductor 45 has a higher current collection and transmission efficiency within this ratio range, thereby ensuring the safe operation of the photovoltaic module 100 while improving the photoelectric conversion efficiency of the photovoltaic module 100.

[0056] In some embodiments, the electrode 31 can be a combination of one or more of the main grid line, the thin grid line, the thickened grid line segment, and the PAD point. Among them, the "main grid line" can also be called the main grid (i.e., Busbar), the busbar electrode 31 or the busbar grid line, which is used to collect the current of the thin grid line; the "fine grid line" can also be called a thin grid, a collector grid line, a collector electrode, a sub-grid, etc. The fine grid line includes a positive fine grid line and a negative fine grid line, which are respectively used to collect the majority carriers or minority carriers of different doping regions; the "thickened grid line segment" refers to the part of the grid line used for electrical connection, and its width is greater than the width of other parts of the grid line; the PAD point can also be called a pad. The material of the electrode 31 can be a metal with relatively high electrical conductivity, such as silver, silver alloy, etc., to improve the current collection and transmission capacity of the battery cell 3. It can also be a relatively cheap metal, such as copper, copper alloy, aluminum, aluminum alloy, etc., to reduce the cost of the photovoltaic module 100. The specific material and component ratio are not limited.

[0057] As understood by those skilled in the art, a longitudinal section refers to the surface presented after cutting an object along the direction of the axis of the object. In the present application, the joint surface of the conductor 45 and the electrode 31 has a first center point, the joint surface of the conductor 45 and the conductive layer 42 has a second center point, and the axis of the conductor 45 refers to the line connecting the first center point and the second center point. The conductor 45 is a conductor, and when the photovoltaic module 100 generates electricity, the direction of the current usually flows along the axis of the conductor 45.

[0058] refer to Figure 6The conductor 45 is arranged between the electrode 31 of the battery cell 3 and the conductive layer 42 for electrical interconnection. In the longitudinal section of the conductor 45, the length of the first side 451 of the conductor 45 in contact with the electrode 31 of the battery cell 3 is D1, the length of the second side 452 of the conductor 45 in contact with the conductive layer 42 is D2, the first side 451 and the second side 452 are arranged on opposite sides of the conductor 45, and the length of the third side 453 at the narrowest point between the first side 451 and the second side 452 is D3. The width of the electrode 31 in the direction of the first side 451 is D.

[0059] In this application, the cross section of the conductor 45 refers to a plane figure obtained by cutting the conductor 45 in a plane parallel to the battery cell 3. In some embodiments, the cross section of the conductor 45 can be regular or irregular, the same or different, circular, elliptical, etc.

[0060] In some embodiments, in the cross-section of the conductor 45, the area of ​​the first cross-section through the first edge 451 is S1, the area of ​​the second cross-section through the second edge 452 is S2, and the area of ​​the third cross-section through the third edge 453 is S3, and: S1>S3, and / or S2>S3.

[0061] The larger the S1 is, the larger the contact area between the conductor 45 and the electrode 31 is, the smaller the contact resistance between the conductor 45 and the electrode 31 is, and the stronger the ability of the conductor 45 to collect the current on the electrode 31 is, thereby increasing the power of the photovoltaic module 100. On the other hand, the larger the contact area between the conductor 45 and the electrode 31 is, the greater the welding pull-out force between the conductor 45 and the electrode 31 is, which effectively prevents the photovoltaic module 100 from falling off or breaking at the welding point due to external factors such as wind pressure and hail during use. The smaller the S3 is, the smaller the area of ​​the third cross section through the third side 453 is, that is, the middle part of the conductor 45 is thinner, which can effectively reduce the amount of conductive paste such as solder paste or conductive glue, saving costs. In addition, such a design makes it possible for a gap to exist in the through hole 44 after the conductor 45 is filled into the through hole 44. In this way, in the process of preparing the photovoltaic module 100, even if there are errors introduced by the process such as the layout offset of the battery cell 3, the printing offset of the electrode 31, the offset of the conductor 45, the offset of the insulating layer 41, and the offset of the through hole 44 in the insulating layer 41 due to heat shrinkage or punching, resulting in the position mismatch between the electrode 31 and the through hole 44 in the insulating layer 41, it will not cause the conductor 45 in the through hole 44 to be unable to connect and conduct electricity. Therefore, the conductor 45 structure designed in this way can not only ensure the effective transmission of current, but also has a certain fault tolerance for the preparation process, so it can also correspondingly improve the yield of the photovoltaic module 100. In this application, S1>S3, the conductor 45 has a strong ability to collect the current on the electrode 31, improves the power of the photovoltaic module 100, the welding pull-out force between the conductor 45 and the electrode 31 is large, and the reliability of the photovoltaic module 100 is high. Reduce the difficulty of the process, save the amount of conductive paste, and reduce costs.

[0062] The larger S2 is, on the one hand, the larger the contact area between the conductor 45 and the conductive layer 42, the smaller the contact resistance between the conductor 45 and the conductive layer 42, and the higher the current transmission efficiency, thereby increasing the power of the photovoltaic module 100. On the other hand, the larger the contact area between the conductor 45 and the conductive layer 42, the greater the welding pull-out force between the conductor 45 and the conductive layer 42, which effectively prevents the photovoltaic module 100 from falling off or breaking at the weld due to external factors such as wind pressure and hail during use. In the present application, S2>S3, the current transmission capacity between the conductor 45 and the conductive layer 42 is strong, the power of the photovoltaic module 100 is improved, the welding pull-out force between the conductor 45 and the conductive layer 42 is large, and the reliability of the photovoltaic module 100 is high. At the same time, the process difficulty is reduced, the amount of conductive paste used is saved, and the cost is reduced.

[0063] The current collection and transmission efficiency of the conductor 45 depends on the contact resistance between the conductor 45 and the electrode 31 on the battery cell 3, the contact resistance between the conductor 45 and the conductive layer 42, and the body resistance of the conductor 45, wherein the contact resistance has a greater impact on the current collection and transmission capability than the body resistance. When S1>S3 and S2>S3, the current collection capability of the conductor 45 on the electrode 31 is enhanced, and at the same time, the current transmission capability between the conductor 45 and the conductive layer 42 is also significantly enhanced. Reducing S3 has little effect on the current collection and transmission efficiency of the conductor 45, and while ensuring the current collection and transmission efficiency, the amount of conductive paste such as solder paste or conductive glue is greatly reduced, saving costs. In addition, such a design makes it possible to have a gap in the through hole 44 after the conductor 45 is filled into the through hole 44. In this way, in the process of preparing the photovoltaic module 100, even if there are errors introduced by the process such as the layout deviation of the battery cell 3, the printing deviation of the electrode 31, the deviation of the conductor 45, the deviation of the insulating layer 41, the deviation of the through hole 44 in the insulating layer 41 due to heat shrinkage or punching, etc., resulting in the position mismatch between the electrode 31 and the through hole 44 in the insulating layer 41, it will not cause the conductor 45 in the through hole 44 to be unable to connect and conduct electricity. Therefore, the conductor 45 structure designed in this way can not only ensure the effective collection and transmission of current and reduce costs, but also has a certain fault tolerance for the preparation process, thereby improving the yield of the photovoltaic module 100.

[0064] Continue to refer Figure 6 The conductor 45 is disposed in the through hole 44 in the insulating layer 41, and is used to electrically interconnect the electrode 31 on the battery body 32 with the conductive layer 42 in the conductive back plate 4, and the conductor 45 is a columnar structure.

[0065] As understood by those skilled in the art, a "column" is a shape in which two faces are parallel and identical to each other, and can be divided into cylinders and prisms. In a cylinder, there are two faces that are parallel and identical to each other, and the intersection lines of each of the remaining two adjacent faces are parallel to each other. Among them, the two faces that are parallel and identical to each other can be respectively called "upper base surface" and "lower base surface", and the surface connecting the upper base surface and the lower base surface is called the side surface. In this application, "quasi-column" refers to two faces that are parallel to each other but have the same or similar shapes. Therefore, if the columnar structure is considered to be a structure in which the upper base surface and the lower base surface are consistent, then the quasi-column structure in this application is a structure in which the upper base surface and the lower base surface are not completely identical. Therefore, it can be understood that, Figure 6 Only one case of a columnar structure of the conductor 45 is shown, and the conductor 45 may also have other structures.

[0066] In some embodiments, the conductor 45 is a cylindrical structure, wherein the upper bottom surface and the lower bottom surface are both circular. The corresponding battery cell 3 may be a multiple-busbar (MBB) battery cell 3 .

[0067] In some embodiments, the conductor 45 is an elliptical column structure, wherein the upper bottom surface and the lower bottom surface are both elliptical. The corresponding battery cell 3 can be a 0-Busbar (abbreviated as 0BB) battery cell 3.

[0068] In some embodiments, the thickness of the intermetallic compound layer at the interface between the conductor 45 and the electrode 31 is 0.5-3 μm, such as 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm. In some embodiments, the thickness of the intermetallic compound layer at the interface between the conductor 45 and the conductive layer 42 is 0.5-3 μm, such as 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm. By controlling the thickness of the intermetallic compound layer within the above range, such a structure can provide a greater tensile strength, thereby improving the welding quality.

[0069] In some embodiments, the first cross section may be a cross section of the intermetallic compound layer at the interface where the conductor 45 contacts the electrode 31 , and the second cross section may be a cross section of the intermetallic compound layer at the interface where the conductor 45 contacts the conductive layer 42 .

[0070] In the present application, in the longitudinal section of the conductor 45, the bottom angle 454 is the angle between the tangent of the side in the plane figure of the longitudinal section and the first side 451. In some embodiments, the bottom angle 154 is 30°-85°, for example, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°. The size of the bottom angle 454 reflects the gradient of the cross-sectional area of ​​the conductor 45. The larger the bottom angle 454, the better the tensile strength. However, when the bottom angle 454 is greater than 85°, the amount of the conductor 45 is large, but the current transmission efficiency is improved less, and the process fault tolerance is sacrificed, and the input-output ratio is small. When the bottom angle 454 is less than 30°, the gradient of the cross-sectional area of ​​the conductor 45 is large, the tensile strength is poor, and the product reliability requirements cannot be met.

[0071] Optionally, the bottom angle 454 is 60°-70°. By controlling the angle of the bottom angle 454 within the above range, the gradient of the cross-sectional area of ​​the conductor 45 is more moderate, the conductor 45 has better mechanical strength such as tensile strength and welding pull-out force, and the conductive performance is also better. In addition, such a design allows the through hole 44 to have a gap after the conductor 45 is filled. In this way, even in the process of preparing the photovoltaic module 100, even if there are errors introduced by the process such as the layout offset of the battery cell 3, the printing offset of the electrode 31, the offset of the conductor 45, the offset of the insulating layer 41, and the offset of the through hole 44 in the insulating layer 41 due to heat shrinkage or punching, resulting in the position of the electrode 31 and the through hole 44 in the insulating layer 41 not corresponding, it will not cause the conductor 45 in the through hole 44 to be unable to connect and conduct electricity. Therefore, the conductor 45 structure designed in this way can not only ensure the effective collection of current, but also has a certain fault tolerance for the preparation process, so it can also correspondingly improve the yield of the photovoltaic module 100.

[0072] It can be understood that the conductor 45 is formed by curing a conductive paste such as solder paste or conductive glue. Therefore, by controlling the parameters of the preparation process of the conductor 45, such as upper and lower lamination temperatures, temperature gradient, pressure, pressure gradient, lamination time, etc., and by selecting the material for preparing the conductor 45, such as a material with a specific melting point and a certain wettability on the electrode 31 and the conductive layer 42, a conductor 45 with different morphologies can be obtained.

[0073] As understood by those skilled in the art, the melting point is the temperature at which a solid changes its physical state from solid (melts) to liquid. It is understood that in the photovoltaic module 100 of the present application, the conductor 45 will change to liquid after its temperature reaches its melting point. In the present application, considering the safe operating temperature of the photovoltaic module 100, the melting point of the conductor 45 should be slightly lower than the safe operating temperature of the photovoltaic module 100, so that before the temperature reaches the maximum safe operating temperature that the photovoltaic module 100 can withstand, the conductor 45 can be fused to prevent the local temperature from exceeding a certain limit, which may cause permanent damage such as partial burning of the photovoltaic module 100, dark spots, aging of the packaging material, and even cause safety hazards. Therefore, in the present application, the melting point of the conductor 45 is greater than or equal to 140°C and less than or equal to 160°C, for example, 140°C, 145°C, 150°C, 155°C, 160°C. Optionally, the melting point of the conductor 45 is greater than or equal to 145°C and less than or equal to 155°C.

[0074] As understood by those skilled in the art, specific heat capacity refers to the ratio of the amount of heat absorbed by a certain mass of a substance when the temperature rises to the product of its mass and the temperature rise, and is used to indicate the ability of an object to absorb or dissipate heat. In some embodiments, the specific heat capacity of the conductor 45 is greater than or equal to 150 J / (kg·K) and less than or equal to 250 J / (kg·K), for example, 150 J / (kg·K), 160 J / (kg·K), 170 J / (kg·K), 180 J / (kg·K), 190 J / (kg·K), 200 J / (kg·K), 210 J / (kg·K), 220 J / (kg·K), 230 J / (kg·K), 240 J / (kg·K), 250 J / (kg·K). It can be seen that the conductor 45 has a high specific heat capacity, so that when the local temperature of the battery cell 3 is high, it can effectively absorb heat, ensuring that the temperature fluctuation of the conductor 45 itself is not large, thereby ensuring the efficient operation of the photovoltaic module 100.

Claims

1. A photovoltaic module, characterized in that: The photovoltaic module comprises: a battery cell, a conductor and a conductive back plate. The battery cell comprises a battery body and electrodes arranged on the battery body; The conductive backplane comprises an insulating layer, a conductive layer and a back adhesive film stacked in sequence, wherein the insulating layer has a plurality of through holes penetrating the insulating layer; A plurality of the conductors are arranged in an array between the battery cell and the conductive backplane, the conductors are electrically interconnected with the electrodes and the conductive layer through the through holes on the insulating layer, the melting point of the conductors is greater than or equal to 140°C and less than or equal to 160°C, and there is a gap between the conductors and the through holes so that when the local temperature of the battery cell reaches the melting point of the conductors, the conductors corresponding to the local part of the battery cell melt.

2. The photovoltaic module according to claim 1, characterized in that: A plurality of the electrical conductors are disposed in one of the through holes.

3. The photovoltaic module according to claim 1, characterized in that: One of the conductors is disposed in one of the through holes.

4. The photovoltaic module according to claim 3, characterized in that: The ratio of the volume of the conductor to the volume of the through hole is greater than or equal to 25% and less than or equal to 45%.

5. The photovoltaic module according to claim 3, characterized in that: The ratio of the volume of the conductor to the volume of the through hole is greater than or equal to 30% and less than or equal to 40%.

6. The photovoltaic module according to claim 1, characterized in that: The electrode is a combination of one or more of a main grid line, a thin grid line, a PAD point or a thickened grid line segment.

7. The photovoltaic module according to claim 1, characterized in that: The area of ​​the first cross-section of the conductor in contact with the electrode is S1, the area of ​​the second cross-section of the conductor in contact with the conductive layer is S2, the first cross-section and the second cross-section are arranged on opposite sides of the conductor, and the area of ​​the third cross-section between the first cross-section and the second cross-section corresponding to the narrowest part in the longitudinal section of the conductor is S3, and: S1>S3, and / or S2>S3.

8. The photovoltaic module according to claim 1, characterized in that: The thickness of the intermetallic compound layer at the interface between the conductor and the electrode is greater than or equal to 0.5 μm and less than or equal to 3 μm, and / or the thickness of the intermetallic compound layer at the interface between the conductor and the conductive layer is greater than or equal to 0.5 μm and less than or equal to 3 μm.

9. The photovoltaic module according to claim 1, characterized in that: In the longitudinal section of the conductor, a base angle is greater than or equal to 25° and less than or equal to 85°.

10. The photovoltaic module according to claim 9, characterized in that: In the longitudinal section of the conductor, a base angle is greater than or equal to 60° and less than or equal to 70°.

11. The photovoltaic module according to claim 1, characterized in that: The conductor is a column-like structure.

12. The photovoltaic module according to claim 11, characterized in that: The columnar-like structure includes: a cylindrical-like structure and an elliptical-column-like structure.

13. The photovoltaic module according to claim 1, characterized in that: The material of the conductor is an alloy containing tin and bismuth.

14. The photovoltaic module according to claim 1, characterized in that: The melting point of the conductor is greater than or equal to 145° C. and less than or equal to 155° C.

15. The photovoltaic module according to claim 1, characterized in that: The specific heat capacity of the conductor is greater than or equal to 150 J / (kg•K) and less than or equal to 250 J / (kg•K).

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