Back contact cells, stacked cells and photovoltaic modules

Abstract

The application relates to the photovoltaic technology field and discloses a back contact cell, a laminated cell and a photovoltaic module, which can at least improve the testing accuracy of the back contact cell. The back contact cell comprises a substrate, a first fine grid and a second fine grid. The substrate has opposite first and second surfaces. The first and second fine grids are alternately distributed on the second surface along a first direction. The back contact cell further comprises a first connecting structure and a second connecting structure, both of which are connected with the first fine grid and have a spacing with the second fine grid. The back contact cell further comprises a third connecting structure and a fourth connecting structure, both of which are connected with the second fine grid and have a spacing with the first fine grid. In a second direction intersecting the first direction, the size of the first connecting structure is larger than that of the second connecting structure, and the size of the third connecting structure is larger than that of the fourth connecting structure.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a back contact cell, a tandem cell, and a photovoltaic module. Background Technology

[0002] As fossil fuels are gradually depleted, solar energy is becoming increasingly widely used as a new energy alternative. A solar cell is a device that converts sunlight into electrical energy. Solar cells utilize the photovoltaic principle to generate charge carriers, which are then extracted using electrodes, thus facilitating the efficient use of electrical energy.

[0003] Back-contact solar cells are a type of solar cell where all the grid lines are located on the back of the cell. Because there are no metal grid electrodes obstructing the front of the cell, back-contact solar cells increase light absorption efficiency, significantly improve short-circuit current, and effectively increase conversion efficiency, making them a promising technology with excellent future prospects. Summary of the Invention

[0004] The purpose of this application is to provide a back contact battery, a tandem battery, and a photovoltaic module, which can at least improve the testing accuracy of the back contact battery.

[0005] To address the aforementioned technical problems, embodiments of this application provide a back-contact battery. The back-contact battery includes a substrate, a first fine grid, and a second fine grid. The substrate has opposing first and second surfaces. The first and second fine grids are alternately distributed along a first direction on the second surface. The back-contact battery further includes a first connecting structure and a second connecting structure, both connected to the first fine grid and spaced apart from it. The back-contact battery also includes a third connecting structure and a fourth connecting structure, both connected to the second fine grid and spaced apart from it. Along a second direction, the size of the first connecting structure is larger than the size of the second connecting structure, and the size of the third connecting structure is larger than the size of the fourth connecting structure; the second direction is a direction intersecting the first direction.

[0006] An embodiment of this application also provides a stacked battery. The stacked battery includes a bottom cell and a perovskite cell. The bottom cell is the back-contact cell described above. The perovskite cell is located on one side of the bottom cell.

[0007] This application also provides a photovoltaic module. The photovoltaic module includes a cell string, an encapsulating film, and a cover plate. The cell string is formed by connecting multiple back-contact cells as described above, or by connecting multiple stacked cells as described above. The encapsulating film covers the surface of the cell string. The cover plate covers the surface of the encapsulating film that faces away from the cell string.

[0008] The back-contact battery, tandem battery, and photovoltaic module provided in this application have corresponding connection structures for the fine grid connections of different polarities. These connection structures can connect solder strips to form an electrical connection between the solder strips and the fine grid. The first and second connection structures connected to the first fine grid have different dimensions along the second direction, and the third and fourth connection structures connected to the second fine grid have different dimensions along the second direction. By controlling the dimension of the first connection structure along the second direction to be larger than that of the second connection structure, and the dimension of the third connection structure along the second direction to be larger than that of the fourth connection structure, the dimensions of the first and third connection structures along the second direction can be made larger, thereby providing sufficient contact space for the test probe or test metal contact point and avoiding affecting the test accuracy. Furthermore, this reduces the resistance of the first and third connection structures when performing electrical performance tests by connecting probes or metal contact points, thereby reducing current loss and improving the test accuracy of the back-contact battery.

[0009] In some embodiments, along the second direction, the ratio of the size of the first connecting structure to the size of the second connecting structure is 1.5 to 4, and the ratio of the size of the third connecting structure to the size of the fourth connecting structure is 1.5 to 4.

[0010] In some embodiments, the first connection structure includes a first solder joint and a first connecting line extending along a first direction, one end of the first connecting line being connected to the first solder joint; the second connection structure includes a second solder joint and a second connecting line extending along the first direction, one end of the second connecting line being connected to the second solder joint; along the second direction, the size of the first solder joint is larger than the size of the second solder joint, and / or, the size of the first connecting line is larger than the size of the second connecting line.

[0011] In some embodiments, along the first direction, the size of the first solder joint is 0.8mm to 2mm, and the size of the first connecting line is 4.8mm to 10mm; along the second direction, the size of the first solder joint is 0.6mm to 1.2mm, and the size of the first connecting line is 200µm to 300µm.

[0012] In some embodiments, the first connecting line includes a first part and a second part, the first part being located between the first solder joint and the second part, and the size of the first part being larger than the size of the second part along a second direction.

[0013] In some embodiments, the third connection structure includes a third solder joint and a third connecting line extending along a first direction, one end of the third connecting line being connected to the third solder joint; the fourth connection structure includes a fourth solder joint and a fourth connecting line extending along a first direction, one end of the fourth connecting line being connected to the fourth solder joint; along a second direction, the size of the third solder joint is larger than the size of the fourth solder joint, and / or, the size of the third connecting line is larger than the size of the fourth connecting line.

[0014] In some embodiments, along the first direction, the size of the third solder joint is 0.8mm to 2mm, and the size of the third connecting line is 4.8mm to 10mm; along the second direction, the size of the third solder joint is 0.6mm to 1.2mm, and the size of the third connecting line is 200µm to 300µm.

[0015] In some embodiments, the third connecting line includes a third part and a fourth part, the third part being located between the third solder joint and the fourth part along the second direction, and the size of the third part being larger than the size of the fourth part.

[0016] In some embodiments, the fourth connecting structure is located between the first connecting structure and the second connecting structure, the first connecting structure is located on the side of the fourth connecting structure away from the second connecting structure, and the third connecting structure is located on the side of the second connecting structure away from the fourth connecting structure.

[0017] In some embodiments, the first fine grid includes a first segment and a second segment located at both ends of the first segment, wherein the size of the first segment is larger than the size of the second segment along a first direction; the second fine grid includes a third segment and a fourth segment located at both ends of the third segment, wherein the size of the third segment is larger than the size of the fourth segment along a first direction.

[0018] In some embodiments, a fifth connecting line is provided between the first connecting structure and the second connecting structure and the adjacent first segment, and a sixth connecting line is provided between the third connecting structure and the fourth connecting structure and the adjacent third segment. Attached Figure Description

[0019] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0020] Figure 1 This is a schematic diagram of the structure of a back contact battery provided in some embodiments of this application; Figure 2 This is a schematic diagram of the back structure of a back contact battery provided in some embodiments of this application; Figure 3 This is a schematic diagram of the back structure of a back contact battery provided in other embodiments of this application; Figure 4 This is a schematic diagram of the back structure of a back contact battery provided in some embodiments of this application; Figure 5 This is a schematic diagram of the first connection structure in a back contact battery provided in some embodiments of this application; Figure 6This is a schematic diagram of the third connection structure in a back contact battery provided in some embodiments of this application; Figure 7 This is a schematic diagram showing the distribution of test metal contact points on the PCB board of the test device provided in some embodiments of this application; Figure 8 This is a schematic diagram of the structure of a stacked battery provided in some embodiments of this application; Figure 9 This is a schematic diagram of the structure of a stacked battery provided in some other embodiments of this application; Figure 10 These are schematic diagrams of the structure of photovoltaic modules provided in some embodiments of this application; Figure 11 This is a schematic diagram of the structure of a battery string in a photovoltaic module provided in some embodiments of this application. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been presented in the various embodiments of this application to enable readers to better understand this application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in this application can be implemented. The division of the various embodiments below is for the convenience of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0023] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0024] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0025] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0026] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0027] In the description of the embodiments of this application, "electrically connected to one component" means that both components are made of conductive materials, and the two components are in direct contact and connected or connected via other conductive materials. Therefore, when the photovoltaic module is generating electricity, there is current transfer between the two components. "Electrically contacting one component to another" means that the two components are not only in contact, but also, because both components are made of conductive materials, there is current transfer between the two components when the photovoltaic module is generating electricity.

[0028] In the accompanying drawings corresponding to the embodiments of this application, the thickness and / or area of ​​layers, films, panels, regions, etc., are enlarged for better understanding and ease of description. Throughout the specification, the same reference numerals denote the same elements. It should be understood that when describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be an intermediate component between the two components. Conversely, when describing a component on the surface of another component, or a component "directly" on another component, or a component surface on which another component is formed or disposed, it indicates that there is no intermediate component between the two components. Furthermore, when describing a component as "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0029] Back-contact batteries include those with a main grid and those without. In gridless back-contact batteries, the back side lacks a main grid design. Because there is no main grid on the back, it is difficult to establish a stable electrical contact between the test probe or test metal contact point and the surface electrodes of the back-contact battery during electrical performance testing, such as IV (current-voltage) testing. This results in greater testing difficulty and lower reliability and stability. Therefore, electrical performance testing is typically performed using solder joints on the surface of the back-contact battery.

[0030] Currently, electrical performance testing of gridless back-contact batteries is primarily conducted using a PCB (Printed Circuit Board). The PCB has several independent test metal contact points, corresponding to solder joints on the surface of the back-contact battery. When the test metal contact point and the solder joint make contact, circuit continuity is achieved. The metal contact points on the PCB are divided into current test points and voltage test points.

[0031] With the continuous rise in the cost of silver paste, reducing unit consumption and applying low-cost metal pastes have become important ways to control costs for back-contact batteries. This leads to a reduction in the solder joint area, resulting in insufficient contact space for the test metal contacts, which affects test accuracy. Furthermore, when using connecting wires near the solder joint for testing, the conductivity of low-cost metals is often weaker than that of silver, leading to increased resistance. This increases the resistance between current and voltage test points, further impacting test accuracy.

[0032] To improve the testing accuracy of back-contact batteries, some embodiments of this application provide a back-contact battery that, by controlling the width of the connection structure at different solder joint locations, allows for widening of the connection structure used for testing, thereby forming larger solder joint areas and / or wider connecting lines. Larger solder joint areas provide sufficient contact space during testing, avoiding any impact on testing accuracy. Wider connecting lines reduce resistance and current loss, thereby improving the accuracy of the output results during testing.

[0033] The following is combined Figures 1 to 6 This application describes the structure of a back contact battery provided in some embodiments.

[0034] like Figures 1 to 4 As shown, some embodiments of this application provide a back contact battery including a substrate 100, a first fine grid 110, and a second fine grid 120. The substrate 100 has opposing first surfaces 101 and second surfaces 102. The first fine grid 110 and the second fine grid 120 are aligned along a first direction ( Figure 2 (In the direction indicated by the middle arrow A) they are alternately distributed on the second surface 102.

[0035] The back contact battery also includes a first connection structure 130 and a second connection structure 140, both of which are connected to the first fine grid 110 and are spaced apart from the second fine grid 120.

[0036] The back contact battery also includes a third connection structure 150 and a fourth connection structure 160, both of which are connected to the second fine grid 120 and are spaced apart from the first fine grid 110.

[0037] Along the second direction, the size of the first connecting structure 130 is larger than the size of the second connecting structure 140, and the size of the third connecting structure 150 is larger than the size of the fourth connecting structure 160. (In the second direction...) Figure 2 The direction indicated by the middle arrow B is the direction that intersects with the first direction.

[0038] The substrate 100 is used to receive light and generate photogenerated carriers. In some embodiments, the substrate 100 may be a semiconductor substrate.

[0039] In some embodiments, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material may be monocrystalline, polycrystalline, amorphous, or microcrystalline (a state simultaneously possessing both monocrystalline and amorphous states is called microcrystalline). For example, silicon may be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, and microcrystalline silicon.

[0040] In some embodiments, the substrate 100 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium arsenide, perovskite, cadmium telluride, copper indium selenide, etc.

[0041] The substrate 100 can also be a sapphire substrate, a silicon substrate on an insulator, or a germanium substrate on an insulator.

[0042] The substrate 100 can be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type dopant element, which can be at least one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate 100 is doped with a P-type dopant element, which can be at least one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0043] The substrate 100 has a first surface 101 and a second surface 102 facing each other. In some embodiments, the back-contact cell used in a single-glass photovoltaic module is considered a single-sided cell, and the first surface 101 can serve as a light-receiving surface for receiving sunlight, while the second surface 102 serves as a back-lighting surface. In some embodiments, the back-contact cell used in a double-glass module or a bifacial module is considered a bifacial cell, and both the first surface 101 and the second surface 102 can serve as light-receiving surfaces and can both be used to receive sunlight. It is understood that the back-lighting surface referred to in the embodiments of this application can also receive sunlight, but the degree of sunlight reception is weaker than that of the light-receiving surface, and therefore it is defined as a back-lighting surface.

[0044] In some embodiments, a flocking process may be performed on at least one of the first surface 101 and the second surface 102 to form a flocked surface on at least one of the first surface 101 and the second surface 102, thereby enhancing the absorption and utilization rate of the first surface 101 and / or the second surface 102 for incident light.

[0045] In some embodiments, the first surface 101 of the substrate 100 may have a textured structure, which may include a regularly shaped pyramidal textured structure and an irregularly shaped black silicon. The beveled surface of the textured structure can increase the internal reflection of incident light, thereby improving the absorption and utilization rate of incident light by the substrate 100, and thus improving the battery efficiency of the back contact battery.

[0046] In some embodiments, the front side of the substrate 100 has a front surface field (FSF), and the conductivity type of the doped ions in the front surface field is the same as that of the doped ions in the substrate 100. By utilizing the field passivation effect, the surface minority carrier concentration can be reduced, thereby reducing the surface recombination rate, and at the same time, the series resistance can be reduced, improving the electron transport capability.

[0047] In some embodiments, the back contact battery includes a front passivation layer 103, which is located on the front side of the back contact battery and is considered as a front passivation layer. The front passivation layer 103 can be a single-layer structure or a stacked structure, and the material of the front passivation layer 103 can include one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, and aluminum oxide.

[0048] In some embodiments, the back surface of the substrate 100 is a polished surface, which refers to a smooth surface formed by removing the textured surface structure through a polishing solution or laser etching. After polishing, the smoothness of the back surface increases, the reflection of long-wavelength light increases, and the secondary absorption of incident light is promoted, thereby increasing Isc (short-circuit current). At the same time, due to the reduction of the specific surface area of ​​the back surface, back recombination is reduced, and the back passivation effect can be improved.

[0049] In some embodiments, the back side of the back contact battery includes a first doped region 104 and a second doped region 105 arranged sequentially at intervals. The first doped region 104 is doped with dopant ions of the same conductivity type as the substrate 100, and the second doped region 105 is doped with dopant ions of a different conductivity type than the substrate 100. For example, if the substrate 100 is an N-type substrate, the first doped region 104 is an N-type doped region, and the second doped region 105 is a P-type doped region, then the second doped region 105 and the substrate 100 form a PN junction, effectively shunting charge carriers.

[0050] In some embodiments, the doping concentration of doped ions in the first doped region 104 is greater than the doping concentration of doped ions in the substrate 100, and a high-low junction is formed between the first doped region 104 and the substrate 100 to enhance the carrier separation capability.

[0051] The first doped region 104 and the second doped region 105 have a gap or isolation structure to achieve automatic isolation between regions with different conductivity types, which can prevent leakage caused by contact between the heavily doped P region and N region on the back of the back contact battery.

[0052] In some embodiments, the back contact battery includes a back passivation layer 106, which is located on the surfaces of the first doped region 104 and the second doped region 105.

[0053] The back passivation layer 106 may include a single-layer film structure or a stacked film structure, and the material of the back passivation layer 106 may include any one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, and aluminum oxide.

[0054] In some embodiments, the back contact battery includes a first electrode 107 and a second electrode 108. The first electrode 107 penetrates the back passivation layer 106 and is electrically connected to the first doped region 104; the second electrode 108 penetrates the back passivation layer 106 and is electrically connected to the second doped region 105.

[0055] The first electrode 107 and the second electrode 108 are fine grids (sub-grids) of the back contact battery, used to collect and summarize the current of the back contact battery. The first electrode 107 and the second electrode 108 can be formed by burn-through slurry sintering. The materials of the first electrode 107 and the second electrode 108 can include one or more of aluminum, silver, gold, nickel, molybdenum and copper.

[0056] like Figures 2 to 4 As shown, the first fine gate 110 and the second fine gate 120 are alternately distributed along the first direction, and the first fine gate 110 and the second fine gate 120 extend along the second direction, which is the direction that intersects with the first direction.

[0057] The intersection of the first and second directions includes situations where the first and second directions are perpendicular, or where the angle formed by the first and second directions is obtuse, or where the angle formed by the first and second directions is acute. In some examples, the angle between the first and second directions can be 10° to 90°, for example, 10°, 20°, 45°, 55°, 70°, 82°, or 90°. In still other examples, the angle between the first and second directions can also be 45° to 90°.

[0058] The connection structure corresponds to the back contact battery surface connection solder strip 50 ( Figure 10 (As shown in the diagram). The connecting structure connects to the fine grid, serving to collect the current from the fine grid, allowing the current generated by the back contact battery to reach the solder strip 50 through the connecting structure. The connecting structure includes solder joints, where the solder strip 50 can be soldered to form an electrical connection with the fine grid.

[0059] Both the first connecting structure 130 and the second connecting structure 140 are electrically connected to the first fine grid 110, serving as connecting structures for collecting the current on the first fine grid 110, and for collecting the charge carriers collected by the first fine grid 110. The first connecting structure 130 and the second connecting structure 140 can be used as parts to be bonded and / or welded to the solder ribbon 50, so that an electrical connection is formed between the solder ribbon 50 and the first fine grid 110. In practice, the first connecting structure 130 and the second connecting structure 140 on the same back contact battery can be connected to the same solder ribbon 50, in which case the first connecting structure 130 and the second connecting structure 140 are arranged along a first direction. Alternatively, the first connecting structure 130 and the second connecting structure 140 on the same back contact battery can be connected to different solder ribbons 50, in which case the first connecting structure 130 and the second connecting structure 140 are staggered. Figure 2 The following example illustrates the distribution of the first connecting structure 130 and the second connecting structure 140 at positions that mate with different solder strips 50.

[0060] The dimension of the first connecting structure 130 along the second direction corresponds to the width of the first connecting structure 130, and the dimension of the second connecting structure 140 along the second direction corresponds to the width of the second connecting structure 140. By making the dimension of the first connecting structure 130 along the second direction larger than the dimension of the second connecting structure 140 along the second direction, the dimension of the first connecting structure 130 along the second direction can be made larger, thereby making the width of the first connecting structure 130 larger. In this way, the contact space formed by the first connecting structure 130 can be larger, thus avoiding affecting the test accuracy.

[0061] Both the third connection structure 150 and the fourth connection structure 160 are electrically connected to the second fine grid 120, serving as connection structures to collect the current on the second fine grid 120, and are used to collect the charge carriers collected by the second fine grid 120. The third connection structure 150 and the fourth connection structure 160 can be used as parts to be bonded and / or welded to the solder ribbon 50, so that an electrical connection is formed between the solder ribbon 50 and the second fine grid 120. In practice, the third connection structure 150 and the fourth connection structure 160 on the same back contact battery can be connected to the same solder ribbon 50, in which case the third connection structure 150 and the fourth connection structure 160 are arranged along the first direction. Alternatively, the third connection structure 150 and the fourth connection structure 160 on the same back contact battery can be connected to different solder ribbons 50, in which case the third connection structure 150 and the fourth connection structure 160 are staggered. Figure 2 The following example illustrates the distribution of the third connecting structure 150 and the fourth connecting structure 160 at positions that mate with different solder strips 50.

[0062] The dimension of the third connecting structure 150 along the second direction corresponds to the width of the third connecting structure 150, and the dimension of the fourth connecting structure 160 along the second direction corresponds to the width of the fourth connecting structure 160. By making the dimension of the third connecting structure 150 along the second direction larger than the dimension of the fourth connecting structure 160 along the second direction, the dimension of the third connecting structure 150 along the second direction can be made larger, thereby making the width of the third connecting structure 150 larger. In this way, the contact space formed by the third connecting structure 150 can be larger, thus avoiding affecting the test accuracy.

[0063] In some embodiments of this application, the back contact battery has corresponding connection structures for connecting fine grids of different polarities. These connection structures can connect solder ribbons 50 to form an electrical connection between the solder ribbons 50 and the fine grids. The first connection structure 130 and the second connection structure 140, connected to the first fine grid 110, have different dimensions along the second direction. Similarly, the third connection structure 150 and the fourth connection structure 160, connected to the second fine grid 120, have different dimensions along the second direction. By controlling the dimension of the first connection structure 130 along the second direction to be larger than that of the second connection structure 140, and the dimension of the third connection structure 150 along the second direction to be larger than that of the fourth connection structure 160, the dimensions of the first connection structure 130 and the third connection structure 150 along the second direction can be made larger, thereby providing sufficient contact space for test probes or test metal contact points and avoiding affecting test accuracy.

[0064] On the other hand, the larger size of the first connection structure 130 and the third connection structure 150 can reduce the resistance of the first connection structure 130 and the third connection structure 150 when performing electrical performance tests on the connection probe or metal contact point, thereby reducing current loss and improving the testing accuracy of the back contact battery.

[0065] The electrical performance testing of back-contact batteries includes IV testing, and the accuracy of IV testing is a core indicator for measuring test quality. The first connection structure 130 and the third connection structure 150 are used to contact test probes or test metal contacts of different polarities in the testing device. The number of first connection structures 130 and third connection structures 150 used for testing can be one, two, three, four, or six, respectively. Increasing the width of the first connection structure 130 and the third connection structure 150 allows the positive and negative electrode test probes or positive and negative electrode test metal contacts of the testing device to form contact with the first connection structure 130 and the third connection structure 150, respectively. A larger contact area or a wider connection line can improve the accuracy of the test results. Specifically, when using the solder joint of the connection structure as the test contact area, a solder joint with a larger width can provide sufficient contact space, thus forming sufficient contact with the test probe or test metal contact point, avoiding affecting test accuracy and improving test accuracy. When using the connection line on one side of the solder joint as the test contact area, a connection line with a larger width can reduce resistance, thereby reducing current loss and improving test accuracy.

[0066] In some embodiments, along the second direction, the ratio of the size of the first connecting structure 130 to the size of the second connecting structure 140 is 1.5 to 4, and the ratio of the size of the third connecting structure 150 to the size of the fourth connecting structure 160 is 1.5 to 4.

[0067] That is, the dimension of the first connecting structure 130 along the second direction can be 1.5 to 4 times the dimension of the second connecting structure 140 along the second direction. The dimension of the third connecting structure 150 along the second direction can be 1.5 to 4 times the dimension of the fourth connecting structure 160 along the second direction.

[0068] By controlling the ratio of the dimension of the first connecting structure 130 along the second direction to the dimension of the second connecting structure 140 along the second direction to be 1.5 to 4, and the ratio of the dimension of the third connecting structure 150 along the second direction to the dimension of the fourth connecting structure 160 along the second direction to be 1.5 to 4, the dimensions of the first connecting structure 130 and the third connecting structure 150 along the second direction can be kept within a suitable range. This avoids the situation where the dimensions of the first connecting structure 130 and the third connecting structure 150 along the second direction are too small, resulting in a limited increase in the solder joint area or a limited decrease in resistance. It also avoids the situation where the dimensions of the first connecting structure 130 and the third connecting structure 150 along the second direction are too large, resulting in a sharp increase in cost, and avoids adverse light-shielding effects.

[0069] In practice, along the second direction, the ratio of the size of the first connecting structure 130 to the size of the second connecting structure 140 can be 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, or 4. Similarly, the ratio of the size of the third connecting structure 150 to the size of the fourth connecting structure 160 can be 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, or 4.

[0070] Based on the fact that the fine grid includes a first fine grid 110 and a second fine grid 120, the solder ribbon 50 can also be divided into two types: one type is electrically connected to the first fine grid 110 and electrically insulated from the second fine grid 120 to collect the current on the first fine grid 110; the other type is electrically connected to the second fine grid 120 and electrically insulated from the first fine grid 110 to collect the current on the second fine grid 120. For any solder ribbon 50 connected to the same back contact battery, it is only electrically connected to the plurality of first fine grids 110 of the back contact battery, or electrically connected to the plurality of second fine grids 120 of the back contact battery.

[0071] In other words, different connection structures on the back of the battery can connect to the first solder strip 51 ( Figure 11 (as shown) and the second solder strip 52 ( Figure 11One of the first solder strips 51 and the second solder strip 52 (as shown) is used to achieve an electrical connection between the solder strip 50 and the grid. The first solder strip 51 and the second solder strip 52 can be arranged alternately along the second direction. For the first solder strip 51 and the second solder strip 52 connected to the same back contact battery, the first solder strip 51 is used to collect the current on one of the first grid 110 and the second grid 120 on the back contact battery, and the second solder strip 52 is used to collect the current on the other of the first grid 110 and the second grid 120 on the back contact battery. Based on this, there is a gap between adjacent first grids 110 and adjacent second grids 120. The gap between adjacent first grids 110 is used for one of the first solder strips 51 and the second solder strip 52 to extend along the first direction and form an electrical connection with a plurality of second grids 120, and the gap between adjacent second grids 120 is used for the other of the first solder strips 51 and the second solder strip 52 to extend along the first direction and form an electrical connection with a plurality of first grids 110. Figures 2 to 4 The following explanation uses the battery structure before half-cell splitting as an example. When half-cells are split and strung together, one of two adjacent half-cells can be defined as the first half-cell, and the other as the second half-cell. The first solder strip 51 is connected to either the first connection structure 130 or the second connection structure 140 on the first half-cell, and also to either the third connection structure 150 or the fourth connection structure 160 on the second half-cell. The second solder strip 52 is connected to either the third connection structure 150 or the fourth connection structure 160 on the first half-cell, and also to either the first connection structure 130 or the second connection structure 140 on the second half-cell.

[0072] The edge grid is located on the side of the solder joint near the edge of the back contact cell. Current can be collected through the connecting wire on one side of the solder joint. In other words, the edge grid does not need to be directly connected to the solder ribbon 50; the connecting wire on the solder joint side can collect current from multiple edge grids and further transfer it to the solder joint. In the subsequent stage of fabricating photovoltaic modules using the back contact cells, the solder ribbon 50 is placed on the solder joint. This helps avoid edge microcracks caused to the back contact cells when the solder ribbon 50 is directly connected to the edge grid, thus improving the yield of the subsequently formed photovoltaic modules.

[0073] like Figures 2 to 4 As shown, the first connection structure 130 may include a first solder joint 131 and a first connecting line 132 extending along a first direction, one end of the first connecting line 132 being connected to the first solder joint 131. The second connection structure 140 may include a second solder joint 141 and a second connecting line 142 extending along a first direction, one end of the second connecting line 142 being connected to the second solder joint 141.

[0074] Along the second direction, the size of the first solder joint 131 is greater than the size of the second solder joint 141, and / or the size of the first connecting line 132 is greater than the size of the second connecting line 142.

[0075] The first connecting line 132 extends to one side of the first solder joint 131 and is integral with the first solder joint 131. The second connecting line 142 extends to one side of the second solder joint 141 and is integral with the second solder joint 141. The first connecting line 132 and the second connecting line 142 can increase the number of fine gates connected by the connection structure, thereby improving the collection efficiency of charge carriers on the first fine gate 110.

[0076] Furthermore, the first connecting line 132 can be closer to the edge of the back contact battery relative to the first solder joint 131, and the second connecting line 142 can be closer to the edge of the back contact battery relative to the second solder joint 141. The first connecting line 132 and the second connecting line 142 can form an electrical connection with the first fine grid 110 near the edge, thereby eliminating the need for the solder ribbon 50 to be directly connected to the first fine grid 110 near the edge. This avoids warping and deformation of the back contact battery edge due to stress, and prevents phenomena such as cracking and microcracks in the back contact battery during processing.

[0077] In practice, the first connecting line 132 and the second connecting line 142 can be connected to three, four, five, or six first fine grids 110 near the edge of the back contact battery, thereby allowing the first solder joint 131 and the second solder joint 141 to form a certain distance from the edge of the back contact battery. The current of the first fine grid 110 located in the edge region can be collected through the first connecting line 132 and the second connecting line 142, and the solder ribbon 50 does not need to be directly connected to the first fine grid 110 located in the edge region. This can reduce the risk of microcracks in the edge region of the back contact battery while ensuring current collection efficiency.

[0078] The larger dimension of the first solder joint 131 along the second direction allows for a larger area, providing ample contact space for the test probe or test metal contact point, thus avoiding impact on test accuracy and improving the accuracy of test results. Similarly, the larger dimension of the first connecting line 132 along the second direction allows for a larger width, reducing resistance and further improving the accuracy of test results. Figure 2 The image shows the widened grid pattern of the first solder joint 131. Figure 3 The image shows the grid pattern after the first connecting line 132 has been widened. Figure 4The image shows the grid pattern after both the first solder joint 131 and the first connecting line 132 have been widened. In practice, when the width of the first solder joint 131 is greater than the width of the second solder joint 141, the width of the first connecting line 132 can be equal to or greater than the width of the second connecting line 142. Conversely, when the width of the first connecting line 132 is greater than the width of the second connecting line 142, the width of the first solder joint 131 can be equal to or greater than the width of the second solder joint 141.

[0079] In some embodiments, along the first direction, the size of the first solder joint 131 can be 0.8mm to 2mm, and the size of the first connecting line 132 can be 4.8mm to 10mm. Along the second direction, the size of the first solder joint 131 can be 0.6mm to 1.2mm, and the size of the first connecting line 132 can be 200µm to 300µm.

[0080] The dimension of the first solder joint 131 along the first direction corresponds to the length of the first solder joint 131, and the dimension of the first solder joint 131 along the second direction corresponds to the width of the first solder joint 131. The dimension of the first connecting line 132 along the first direction corresponds to the length of the first connecting line 132, and the dimension of the first connecting line 132 along the second direction corresponds to the width of the second connecting line 142.

[0081] By controlling the dimension of the first solder joint 131 along the first direction, the welding area can be avoided from being limited due to a small length of the first solder joint 131, thereby avoiding affecting the stability of the connection between the solder strip 50 and the first solder joint 131. It can also avoid the increase in material cost and light-shielding area caused by a large length of the first solder joint 131.

[0082] By controlling the dimensions of the first connecting line 132 along the first direction, it is possible to avoid the risk of microcracks at the edge of the back contact battery being too small, and also to avoid the material cost increasing due to the large length of the first connecting line 132.

[0083] In practice, along the first direction, the dimensions of the first solder joint 131 can be 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, or 2mm, and the dimensions of the first connecting line 132 can be 4.8mm, 5mm, 5.2mm, 5.4mm, 5.6mm, 5.8mm, 6mm, 6.2mm, 6.4mm, 6.6mm, 6.8mm, 7mm, 7.2mm, 7.4mm, 7.6mm, 7.8mm, 8mm, 8.2mm, 8.4mm, 8.6mm, 8.8mm, 9mm, 9.2mm, 9.4mm, 9.6mm, 9.8mm, or 10mm.

[0084] By controlling the dimension of the first solder joint 131 along the second direction, it is possible to avoid the soldering area being limited due to a small width of the first solder joint 131, thereby avoiding affecting the stability of the connection between the solder strip 50 and the first solder joint 131, and ensuring that the first solder joint 131 provides sufficient contact space for the voltage test point when used as a test contact area, thus avoiding affecting the test accuracy. It also avoids the increase in material cost and light-shielding area caused by a large width of the first solder joint 131.

[0085] By controlling the dimensions of the first connecting line 132 along the second direction, it is possible to avoid the first connecting line 132 being too narrow and thus failing to effectively reduce resistance, thereby avoiding large current loss when used as a test contact part for testing, and also avoiding the first connecting line 132 being too wide and thus increasing material costs.

[0086] In practice, along the second direction, the size of the first solder joint 131 can be 0.6mm, 0.8mm, 0.9mm, 1mm, 1.1mm or 1.2mm, and the size of the first connecting line 132 can be 200µm, 210µm, 220µm, 230µm, 240µm, 250µm, 260µm, 270µm, 280µm, 290µm or 300µm.

[0087] In some embodiments, such as Figure 5 As shown, the first connecting line 132 may include a first part 1321 and a second part 1322, with the first part 1321 located between the first solder joint 131 and the second part 1322. Along the second direction, the size of the first part 1321 is larger than the size of the second part 1322.

[0088] In other words, the first connecting line 132 may include a first part 1321 with a larger width and a second part 1322 with a smaller width. The first part 1321 is closer to the first solder joint 131 than the second part 1322. The first connecting line 132 is configured with a varying width. The first part 1321, as the part of the first connecting line 132 closest to the first solder joint 131, can quickly concentrate current to the first solder joint 131. It can also form a section with lower resistance between the second part 1322 and the first solder joint 131, so as to reduce current loss when voltage test points are arranged in the first part 1321.

[0089] In practice, the first connecting line 132 can be configured as having a gradually changing width, or it can be configured as a segmented structure with multiple widths. That is, the width of the first connecting line 132 can gradually change along the first direction, or the first part 1321 of the first connecting line 132 can have a first width, and the second part 1322 can have a second width, with the first width being greater than the second width.

[0090] In some embodiments, along the second direction, the size of the first part 1321 can be 200µm to 300µm, and the size of the second part 1322 can be 100µm to 200µm. For example, the size of the first part 1321 along the second direction can be 200µm, 210µm, 220µm, 230µm, 240µm, 250µm, 260µm, 270µm, 280µm, 290µm, or 300µm, and the size of the second part 1322 along the second direction can be 100µm, 110µm, 120µm, 130µm, 140µm, 150µm, 160µm, 170µm, 180µm, 190µm, or 200µm.

[0091] like Figure 1 As shown, the third connection structure 150 may include a third solder joint 151 and a third connecting line 152 extending along the first direction, one end of the third connecting line 152 being connected to the third solder joint 151. The fourth connection structure 160 may include a fourth solder joint 161 and a fourth connecting line 162 extending along the first direction, one end of the fourth connecting line 162 being connected to the fourth solder joint 161. Along the second direction, the size of the third solder joint 151 is greater than the size of the fourth solder joint 161, and / or the size of the third connecting line 152 is greater than the size of the fourth connecting line 162.

[0092] The third connecting line 152 extends to one side of the third solder joint 151 and is integral with the third solder joint 151. The fourth connecting line 162 extends to one side of the fourth solder joint 161 and is integral with the fourth solder joint 161. The third connecting line 152 and the fourth connecting line 162 can increase the number of fine gates connected by the connection structure, thereby improving the collection efficiency of charge carriers on the second fine gate 120.

[0093] Furthermore, the third connecting line 152 and the fourth connecting line 162 can be closer to the edge of the back contact battery relative to the third solder point 151. The third connecting line 152 and the fourth connecting line 162 can form an electrical connection with the second fine grid 120 near the edge, thereby eliminating the need for the solder ribbon 50 to be directly connected to the second fine grid 120 near the edge. This avoids warping and deformation of the back contact battery edge due to stress, and prevents phenomena such as cracking and microcracks in the back contact battery during processing.

[0094] In practice, the third connecting line 152 and the fourth connecting line 162 can be connected to three, four, five, or six first fine grids 110 near the edge of the back contact battery, thereby allowing the third solder point 151 and the fourth solder point 161 to form a certain distance from the edge of the back contact battery. The current of the second fine grid 120 located in the edge region can be collected through the third connecting line 152 and the fourth connecting line 162. The solder ribbon 50 does not need to be directly connected to the second fine grid 120 located in the edge region, which can reduce the risk of microcracks in the edge region of the back contact battery while ensuring current collection efficiency.

[0095] The larger dimension of the third solder joint 151 along the second direction allows for a larger area, providing ample contact space for the test probe or test metal contact point, thus avoiding impact on test accuracy and improving the accuracy of test results. Similarly, the larger dimension of the third connecting line 152 along the second direction allows for a larger width, reducing resistance and further improving the accuracy of test results. Figure 2 The image shows the widened grid pattern of the third solder point 151. Figure 3 The image shows the grid pattern after the third connecting line 152 has been widened. Figure 4 The image shows the grid pattern after both the third solder joint 151 and the third connecting line 152 have been widened. In practice, when the width of the third solder joint 151 is greater than the width of the fourth solder joint 161, the width of the third connecting line 152 can be equal to or greater than the width of the fourth connecting line 162. Conversely, when the width of the third connecting line 152 is greater than the width of the fourth connecting line 162, the width of the third solder joint 151 can be equal to or greater than the width of the fourth solder joint 161.

[0096] In some embodiments, along the first direction, the size of the third solder joint 151 is 0.8mm to 2mm, and the size of the third connecting line 152 is 4.8mm to 10mm; along the second direction, the size of the third solder joint 151 is 0.6mm to 1.2mm, and the size of the third connecting line 152 is 200µm to 300µm.

[0097] The dimension of the third solder joint 151 along the first direction corresponds to the length of the third solder joint 151, and the dimension of the third solder joint 151 along the second direction corresponds to the width of the third solder joint 151. The dimension of the third connecting line 152 along the first direction corresponds to the length of the third connecting line 152, and the dimension of the third connecting line 152 along the second direction corresponds to the width of the second connecting line 142.

[0098] By controlling the dimension of the third solder joint 151 along the first direction, the welding area can be avoided from being limited due to a small length of the third solder joint 151, thereby avoiding affecting the stability of the connection between the solder strip 50 and the third solder joint 151. It also avoids the increase in material costs and light-shielding area caused by a large length of the third solder joint 151.

[0099] By controlling the dimensions of the third connecting line 152 along the first direction, it is possible to avoid the risk of microcracks at the edge of the back contact battery being too small, and also to avoid the material cost increasing due to the large length of the third connecting line 152.

[0100] In practice, along the first direction, the dimensions of the third solder joint 151 can be 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, or 2mm, and the dimensions of the third connecting line 152 can be 4.8mm, 5mm, 5.2mm, 5.4mm, 5.6mm, 5.8mm, 6mm, 6.2mm, 6.4mm, 6.6mm, 6.8mm, 7mm, 7.2mm, 7.4mm, 7.6mm, 7.8mm, 8mm, 8.2mm, 8.4mm, 8.6mm, 8.8mm, 9mm, 9.2mm, 9.4mm, 9.6mm, 9.8mm, or 10mm.

[0101] By controlling the dimension of the third solder joint 151 along the second direction, the limited welding area caused by the small width of the first solder joint 131 can be avoided, thus preventing any impact on the stability of the connection between the solder strip 50 and the third solder joint 151. Furthermore, the third solder joint 151, when used as a test contact point, can provide sufficient contact space for the voltage test point, thereby preventing any impact on test accuracy. It also avoids the increased material cost and light-shielding area that would result from a larger width of the third solder joint 151.

[0102] By controlling the dimensions of the third connecting line 152 along the second direction, it is possible to avoid the inability to effectively reduce resistance due to the small width of the third connecting line 152, thereby avoiding large current loss when used as a test contact part. It is also possible to avoid the increase in material cost due to the large width of the third connecting line 152.

[0103] In practice, along the second direction, the dimensions of the third solder joint 151 can be 0.6mm, 0.8mm, 0.9mm, 1mm, 1.1mm or 1.2mm, and the dimensions of the third connecting line 152 can be 200µm, 210µm, 220µm, 230µm, 240µm, 250µm, 260µm, 270µm, 280µm, 290µm or 300µm.

[0104] In some embodiments, such as Figure 6 As shown, the third connecting line 152 includes a third part 1521 and a fourth part 1522. The third part 1521 is located between the third solder point 151 and the fourth part 1522. Along the second direction, the size of the third part 1521 is larger than the size of the fourth part 1522.

[0105] In other words, the third connecting line 152 may include a larger third portion 1521 and a smaller fourth portion 1522. The third portion 1521 is closer to the first solder joint 131 than the fourth portion 1522. The third connecting line 152 is configured with a varying width. The third portion 1521, as the part of the third connecting line 152 closest to the first solder joint 131, can quickly concentrate current to the first solder joint 131. It can also form a section with lower resistance between the fourth portion 1522 and the first solder joint 131, so as to reduce current loss when voltage test points are arranged in the third portion 1521.

[0106] In practice, the third connecting line 152 can be configured as having a gradually changing width, or it can be configured as a segmented structure with multiple widths. That is, the width of the third connecting line 152 can gradually change along the first direction, or the third part 1521 of the third connecting line 152 can have a third width, and the fourth part 1522 can have a fourth width, with the third width being greater than the fourth width.

[0107] In some embodiments, the size of the third part 1521 along the second direction can be 200µm to 300µm, and the size of the fourth part 1522 can be 100µm to 200µm. For example, the size of the third part 1521 along the second direction can be 200µm, 210µm, 220µm, 230µm, 240µm, 250µm, 260µm, 270µm, 280µm, 290µm, or 300µm, and the size of the fourth part 1522 along the second direction can be 100µm, 110µm, 120µm, 130µm, 140µm, 150µm, 160µm, 170µm, 180µm, 190µm, or 200µm.

[0108] like Figure 1As shown, the fourth connecting structure 160 can be located between the first connecting structure 130 and the second connecting structure 140. The first connecting structure 130 is located on the side of the fourth connecting structure 160 away from the second connecting structure 140, and the third connecting structure 150 is located on the side of the second connecting structure 140 away from the fourth connecting structure 160.

[0109] In other words, the second connection structure 140 and the fourth connection structure 160 are located in the middle region of the back of the battery, and the first connection structure 130 and the third connection structure 150 are located in the edge region of the battery.

[0110] By widening the end-to-end connection structure at the edge, the flow convergence effect of the weld points at the edge can be improved, while the connection stability of the weld strip 50 at the edge can be enhanced.

[0111] In practice, the connection structure used for electrical performance testing in contact with the voltage test point can also be a connection structure located in other areas. For example, it can be a head-and-tail connection structure that connects to the middle solder strip, or an intermediate connection structure that connects to the middle solder strip.

[0112] like Figures 2 to 4 As shown, the first fine gate 110 may include a first segment 111 and a second segment 112 located at both ends of the first segment 111. Along the first direction, the size of the first segment 111 is larger than the size of the second segment 112. The second fine gate 120 may include a third segment 121 and a fourth segment 122 located at both ends of the third segment 121. Along the first direction, the size of the third segment 121 is larger than the size of the fourth segment 122.

[0113] The dimension of the first segment 111 along the first direction corresponds to the width of the first segment 111, and the dimension of the second segment 112 along the first direction corresponds to the width of the second segment 112. The width of the first segment 111 is greater than the width of the second segment 112, that is, the first segment 111 has a larger width than the second segment 112. By widening a portion of the first fine gate 110, not only can the carrier collection efficiency be improved, but it can also serve as a solder joint when connecting the solder strip 50, effectively improving the connection strength of the solder strip 50 and the connection reliability between the solder strip 50 and the first fine gate 110.

[0114] The dimension of the third segment 121 along the first direction corresponds to the width of the third segment 121, and the dimension of the fourth segment 122 along the first direction corresponds to the width of the fourth segment 122. The width of the third segment 121 is greater than the width of the fourth segment 122, meaning that the third segment 121 has a larger width than the fourth segment 122. By widening a portion of the second fine gate 120, not only can the carrier collection efficiency be improved, but it can also serve as a solder joint when connecting the solder strip 50, effectively improving the connection strength of the solder strip 50 and enhancing the connection reliability between the solder strip 50 and the second fine gate 120.

[0115] In some embodiments, a fifth connecting line 191 may be provided between the first connecting structure 130 and the second connecting structure 140 and the adjacent first segment 111, and a sixth connecting line 192 may be provided between the third connecting structure 150 and the fourth connecting structure 160 and the adjacent third segment 121.

[0116] In other words, the first connecting structure 130 and the second connecting structure 140 can be connected to the widened portion of the adjacent first fine grid 110 via the fifth connecting line 191. The fifth connecting line 191 enables an electrical connection between the first connecting structure 130 or the second connecting structure 140 and the adjacent first segment 111, thereby forming an electrical connection between the first connecting structure 130 or the second connecting structure 140 and the adjacent first fine grid 110. By setting the fifth connecting line 191, the current-gathering effect of the first connecting structure 130 and the second connecting structure 140 can be improved, increasing the current-gathering path and thus improving the current-gathering efficiency.

[0117] The third connecting structure 150 and the fourth connecting structure 160 can be connected to the widened portion of the adjacent second fine grid 120 via a sixth connecting line 192. The sixth connecting line 192 enables an electrical connection between the third connecting structure 150 or the fourth connecting structure 160 and the adjacent third segment 121, thus forming an electrical connection between the third connecting structure 150 or the fourth connecting structure 160 and the adjacent second fine grid 120. The sixth connecting line 192 improves the current-gathering effect of the third connecting structure 150 and the fourth connecting structure 160, increases the current-gathering path, and thereby improves the current-gathering efficiency.

[0118] like Figures 2 to 4 As shown, the first segment 111 of the first fine gate 110 can be flush with the first connecting structure 130 or the second connecting structure 140 to connect with the same solder strip 50. Alternatively, the first segment 111 of the first fine gate 110 can be offset from the first connecting structure 130 and the second connecting structure 140 to form additional connection paths for the solder strip 50. For example, the first segment 111 of the first fine gate 110 near the left or right edge can be offset from the first connecting structure 130 and the second connecting structure 140 to form connection paths for the solder strip 50 near the edge.

[0119] The third segment 121 of a portion of the second fine gate 120 may be flush with the third connecting structure 150 or the fourth connecting structure 160 for connection with the same solder strip 50. Alternatively, the third segment 121 of a portion of the second fine gate 120 may be offset from the third connecting structure 150 and the fourth connecting structure 160 to form additional connection paths for the solder strip 50. For example, the third segment 121 of the second fine gate 120 near the left or right edge may be offset from the third connecting structure 150 and the fourth connecting structure 160 to form connection paths for the solder strip 50 near the edge.

[0120] like Figures 2 to 4 As shown, the back contact battery may further include a first edge grid line 170, which is connected to the first fine grid 110. The first edge grid line 170 includes a first segment 171, a second segment 172, and a third segment 173 connecting the first segment 171 and the second segment 172. The width of the first segment 171 and the second segment 172 is greater than the width of the third segment 173.

[0121] The first edge grid line 170 is positioned near the left edge of the back contact battery. The first edge grid line 170 can simultaneously connect with multiple first fine grids 110, acting as a current-gathering element at the edge. Furthermore, the wider edge portion of the first edge grid line 170 enhances the current-gathering effect at the corners of the grid pattern.

[0122] The back contact battery may further include a second edge grid line 180, which is connected to the second fine grid 120. The second edge grid line 180 includes a fourth segment 181, a fifth segment 182, and a sixth segment 183 connecting the fourth segment 181 and the fifth segment 182. The widths of the fourth segment 181 and the fifth segment 182 are greater than the width of the sixth segment 183.

[0123] The second edge grid line 180 is positioned near the right edge of the back contact battery. The second edge grid line 180 can simultaneously connect with multiple second fine grids 120, acting as a current-gathering element at the edge. Furthermore, the wider edge portion of the second edge grid line 180 enhances the current-gathering effect at the corners of the grid pattern.

[0124] In some embodiments, the back-contact battery further includes an anti-reflection layer located on the side of the back passivation layer 106 away from the substrate 100 and on the side of the front passivation layer 103 away from the substrate 100. A first electrode 107 penetrates the anti-reflection layer and the back passivation layer 106, making electrical contact with a first doped region 104. A second electrode 108 penetrates the anti-reflection layer and the back passivation layer 106, making electrical contact with a second doped region 105. The anti-reflection layer has a high refractive index, reducing reflection damage on the back of the battery. The material of the anti-reflection layer can be any one or more of silicon nitride or silicon oxynitride.

[0125] Figure 7 The diagram shows the structure of the test metal contact points on a PCB board 20 used for electrical performance testing of a back-contact battery. (See diagram for details.) Figure 7 As shown, the test metal contact points on the PCB board 20 correspond to the connection structure and solder joints on the back of the battery. Voltage test points 201 and current test points 202 can be set at positions corresponding to the connection structure of the battery. The voltage test points 201 and current test points 202 are spaced apart, with the spacing controlled to be at least 1 micrometer. Current test points 202 can be set at positions corresponding to the widened fine grid portion of the battery.

[0126] In practice, the size of the current test point 202 that contacts the connecting line on one side of the solder joint can be smaller than the size of the voltage test point 201. Alternatively, the current test point 202 can be extended to the edge of the connecting line away from the solder joint to improve the contact effect and ensure the formation of a smooth circuit.

[0127] During IV testing, the testing device applies a continuously adjustable voltage to the back contact battery and collects data through the test metal contact points. By increasing the solder joint area, voltage test point 201 and current test point 202 can be positioned corresponding to the area of ​​the solder joint, forming sufficient contact area to avoid affecting test accuracy. Furthermore, by widening the connecting line on one side of the solder joint, voltage test point 201 and current test point 202 can be positioned along the extension direction of this connecting line. The reduced resistance of the connecting line on one side of the solder joint decreases current loss, thereby improving the accuracy of the output results during back contact battery testing.

[0128] Figure 7 The following explanation uses the example of setting a voltage test point 201 on the connection line corresponding to the solder joint on the PCB board 20. In this case, the connection line on the solder joint side is widened, and the width of the connection line at the contact position of the voltage test point 201 is greater than the width of the connection line at other positions.

[0129] like Figure 7 As shown, voltage test points 201 can be set at the locations of the connection lines at the beginning and end solder joints, and other test metal contact points are current test points 202. The polarity of different voltage test points 201 is the same as the polarity of the fine grid connected to the contacting connection structure, and the polarity of different current test points 202 is the same as the polarity of the fine grid connected to the contacting connection structure or the polarity of the fine grid in direct contact.

[0130] In practice, a voltage test point 201 can also be set at the position corresponding to the connection line of the intermediate solder joint. Alternatively, a voltage test point 201 can also be set at the position corresponding to the connection structure located in the middle along the horizontal direction.

[0131] In some embodiments, the method for fabricating a back contact battery includes: providing a substrate having one of an N-type dopant element and a P-type dopant element therein.

[0132] In some embodiments, the method for preparing a back contact battery further includes polishing both sides of the substrate to remove the damaged layer on the substrate surface.

[0133] In some embodiments, the method for fabricating a back contact battery further includes texturing the substrate to form a textured structure. In some embodiments, a solution texturing method can be used to prepare the textured structure. The textured structure can increase the number of refractions of light on the surface of the back contact battery, which is beneficial for the absorption of light by the back contact battery, thereby maximizing the utilization rate of solar energy by the back contact battery. For example, if the substrate is monocrystalline silicon, a mixed solution of alkaline solution and alcohol solution can be used to texturize the substrate surface; if the substrate is polycrystalline silicon, an acid solution can be used to texturize the substrate surface. In some embodiments, laser texturing or reactive ion etching (RIE) texturing can be used to prepare the textured structure.

[0134] In some embodiments, the method for fabricating a back contact battery further includes: forming a semiconductor layer, wherein the semiconductor layer is doped with either an N-type dopant or a P-type dopant, i.e., the type of dopant in the semiconductor layer is different from the type of dopant in the substrate. The semiconductor layer is formed by furnace tube diffusion.

[0135] In some embodiments, the method for fabricating a back contact battery further includes: forming a mask layer in a localized region of the semiconductor layer, the mask layer being positioned opposite to a subsequently formed second doped region. The mask layer is made of silicon oxide or silicon nitride. The mask layer is formed using a PECVD method.

[0136] In some embodiments, the method for fabricating a back contact battery further includes: etching a semiconductor layer that is not protected by a mask layer, with the remaining semiconductor layer serving as a second doped region.

[0137] In some embodiments, the method for preparing a back contact battery further includes: heavily doping a portion of the substrate to form a first doped region.

[0138] In some embodiments, the method for fabricating a back contact battery further includes forming a front passivation layer and a back passivation layer. The front passivation layer and the back passivation layer can be formed using atomic layer deposition or PECVD.

[0139] In some embodiments, the fabrication method of the back contact battery further includes: laser grooving or sintering grooving. Laser grooving uses a laser to drill holes or grooves on the back side of a silicon wafer, penetrating part of the back passivation layer and antireflection layer to expose the first doped region and the second doped region. The electrode makes contact with the first doped region or the second doped region through the holes or grooves in the thin film.

[0140] In some embodiments, the method for fabricating a back contact battery further includes: forming a first electrode and a second electrode. A sintering paste is printed onto a back passivation layer and a front passivation layer, and then sintered at high temperature to form the first electrode and the second electrode.

[0141] Some embodiments of this application also provide a stacked battery. For example... Figure 8 As shown, the tandem solar cell includes a bottom cell 30 and a perovskite cell 31. The bottom cell 30 is the back-contact cell described above. The perovskite cell 31 is located on one side of the bottom cell 30.

[0142] Figure 9 This is a schematic diagram of another structure of the stacked battery provided in an embodiment of this application.

[0143] refer to Figure 9 In some embodiments, the perovskite solar cell 31 may include: a first transport layer 311, a perovskite functional layer 312, a second transport layer 313, a transparent conductive layer 314, and an anti-reflection layer 315 stacked together. The first transport layer 311 is directly opposite the bottom solar cell 30.

[0144] In some examples, the first transport layer 311 can be one of an electron transport layer and a hole transport layer, and the second transport layer 313 can be the other of an electron transport layer and a hole transport layer.

[0145] In some embodiments, the band gap width of the perovskite cell 31 is greater than that of the bottom cell 30. Therefore, stacking the perovskite cell 31 on top of the bottom cell 30 can give the stacked cell a wider spectral response range, thereby maximizing the utilization of solar energy and improving the efficiency of the cell.

[0146] In some embodiments, the tandem battery may further include an intermediate connecting layer for electrically connecting the bottom battery 30 and the perovskite battery 31.

[0147] In some embodiments, the intermediate connecting layer is generally a tunnel junction or a very thin metal or transparent electrode composite layer. Optionally, the intermediate connecting layer can be a transparent conductive oxide, which has good optoelectronic properties, high photon transmittance and high conductivity, thereby enabling the perovskite cell 31 and the bottom cell 30 to maintain good ohmic contact.

[0148] In some embodiments, the tandem battery can be configured as a 2T (two-terminal series / two-terminal stacked) structure or a 4T (four-terminal series / four-terminal stacked) structure. The tandem battery can also be configured as a 3T (three-terminal series / three-terminal stacked) structure. The three-terminal stacked structure is mainly used in tandem batteries manufactured by combining back-contact batteries and perovskite batteries, and it produces three electrodes. In the four-terminal stacked battery, the two sub-cells are manufactured independently, and they are only optically connected; their circuits are independent. It can be understood that the perovskite battery 31 and the bottom battery 30 are merely physically stacked, and in reality, they each output independently. Therefore, the four-terminal stacked battery will have two positive electrodes and two negative electrodes.

[0149] Some embodiments of this application also provide a photovoltaic module. For example... Figure 10 and Figure 11 As shown, the photovoltaic module includes a cell string, an encapsulating film 410, and a cover plate. The cell string is formed by connecting multiple back-contact cells 40 as described above, or by connecting multiple stacked cells as described above. The encapsulating film 410 covers the surface of the cell string. The cover plate covers the surface of the encapsulating film 410 that faces away from the cell string.

[0150] In some embodiments, the back contact battery 40 can be electrically connected in the form of a whole cell or sliced ​​cells to form multiple battery strings, which are electrically connected in series and / or parallel. A sliced ​​cell refers to a cell formed by cutting a complete whole cell. Segmented cells can be two-slice cells, three-slice cells, or four-slice cells, etc.

[0151] Multiple back-contact batteries 40 can be electrically connected by solder strips 50.

[0152] In some embodiments, the encapsulating film 410 includes a first encapsulating layer and a second encapsulating layer. The first encapsulating layer covers one of the first and second surfaces of the back contact battery 40, and the second encapsulating layer covers the other of the first and second surfaces of the back contact battery 40. Specifically, at least one of the first and second encapsulating layers can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate (EVA) film, polyethylene octene elastomer (POE) film, or polyethylene terephthalate (PET) film. Alternatively, at least one of the first and second encapsulating layers can also be an EP film, an EPE film, or a PVP film. Among them, EP film refers to a co-extruded film composed of stacked EVA film and POE film; EPE film refers to a co-extruded film formed by sequentially stacking EVA film, POE film, and EVA film; and PVP film refers to a co-extruded film formed by stacking POE film, EVA film, and POE film. Co-extruded films can be prepared by sequentially extruding one or more raw materials onto another pre-made film during the film processing, or by bonding different types of pre-made films together.

[0153] In some cases, the first encapsulation layer and the second encapsulation layer still have a boundary line before lamination. After lamination, the photovoltaic module will no longer have the concept of a first encapsulation layer and a second encapsulation layer. That is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 410.

[0154] In some embodiments, the cover plate can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate facing the encapsulating film 410 can be an uneven surface or a textured surface containing multiple raised structures, thereby increasing the utilization rate of incident light. The cover plate may include a first cover plate 421 and a second cover plate 422, the first cover plate 421 being opposite to the first encapsulation layer, and the second cover plate 422 being opposite to the second encapsulation layer.

[0155] Those skilled in the art will understand that the above embodiments are specific implementations of this application, and in practical applications, various changes can be made in form and detail without departing from the spirit and scope of this application.

Claims

1. A back-contact battery, characterized in that, include: The substrate has a first and a second surface that are opposite to each other. The first and second fine grids are alternately distributed on the second surface along the first direction; Both the first connecting structure and the second connecting structure are connected to the first fine gate and are spaced apart from the second fine gate; Both the third and fourth connection structures are connected to the second fine gate and are spaced apart from the first fine gate. Along the second direction, the size of the first connecting structure is larger than the size of the second connecting structure, the size of the third connecting structure is larger than the size of the fourth connecting structure, and the second direction is the direction that intersects with the first direction.

2. The back contact battery according to claim 1, characterized in that, Along the second direction, the ratio of the size of the first connecting structure to the size of the second connecting structure is 1.5 to 4, and the ratio of the size of the third connecting structure to the size of the fourth connecting structure is 1.5 to 4.

3. The back contact battery according to claim 1, characterized in that, The first connection structure includes a first solder joint and a first connecting line extending along the first direction, one end of the first connecting line being connected to the first solder joint; The second connection structure includes a second solder joint and a second connecting line extending along the first direction, one end of the second connecting line being connected to the second solder joint; Along the second direction, the size of the first solder joint is larger than the size of the second solder joint, and / or the size of the first connecting line is larger than the size of the second connecting line.

4. The back contact battery according to claim 3, characterized in that, Along the first direction, the size of the first solder joint is 0.8mm~2mm, and the size of the first connecting line is 4.8mm~10mm. Along the second direction, the size of the first solder joint is 0.6mm~1.2mm, and the size of the first connecting line is 200µm~300µm.

5. The back contact battery according to claim 3, characterized in that, The first connecting line includes a first part and a second part, the first part being located between the first solder joint and the second part along the second direction, and the size of the first part being larger than the size of the second part.

6. The back contact battery according to claim 1, characterized in that, The third connection structure includes a third solder joint and a third connection line extending along the first direction, one end of the third connection line being connected to the third solder joint. The fourth connection structure includes a fourth solder joint and a fourth connection line extending along the first direction, one end of the fourth connection line being connected to the fourth solder joint. Along the second direction, the size of the third solder joint is greater than the size of the fourth solder joint, and / or the size of the third connecting line is greater than the size of the fourth connecting line.

7. The back contact battery according to claim 6, characterized in that, Along the first direction, the size of the third solder joint is 0.8mm~2mm, and the size of the third connecting line is 4.8mm~10mm. Along the second direction, the size of the third solder joint is 0.6mm~1.2mm, and the size of the third connecting line is 200µm~300µm.

8. The back contact battery according to claim 6, characterized in that, The third connecting line includes a third part and a fourth part. The third part is located between the third solder joint and the fourth part. Along the second direction, the size of the third part is larger than the size of the fourth part.

9. The back contact battery according to claim 1, characterized in that, The fourth connecting structure is located between the first connecting structure and the second connecting structure, the first connecting structure is located on the side of the fourth connecting structure away from the second connecting structure, and the third connecting structure is located on the side of the second connecting structure away from the fourth connecting structure.

10. The back contact battery according to claim 1, characterized in that, The first fine grid includes a first segment and a second segment located at both ends of the first segment, wherein the size of the first segment is larger than the size of the second segment along the first direction; The second fine grid includes a third segment and a fourth segment located at both ends of the third segment, wherein the size of the third segment is larger than the size of the fourth segment along the first direction.

11. The back contact battery according to claim 10, characterized in that, A fifth connecting line is provided between the first connecting structure and the second connecting structure and the adjacent first segment, and a sixth connecting line is provided between the third connecting structure and the fourth connecting structure and the adjacent third segment.

12. A stacked battery, characterized in that, include: The bottom battery is the back contact battery as described in any one of claims 1 to 11; A perovskite solar cell is located on one side of the bottom cell.

13. A photovoltaic module, characterized in that, include: The battery string is formed by connecting multiple back-contact batteries as described in any one of claims 1 to 11, or by connecting multiple stacked batteries as described in claim 12; An encapsulating film is used to cover the surface of the battery string; A cover plate that covers the surface of the encapsulating film facing away from the battery string.

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