Back contact cell, cell string, cell module and photovoltaic system

Abstract

The present disclosure is applicable to the technical field of solar cells, and provides a back contact cell, a cell string, a cell module and a photovoltaic system. The back contact cell comprises: a cell piece, the cell piece having a front surface and a back surface that are opposite to each other; and a plurality of fingers provided on the back surface, wherein the plurality of fingers extend in a first direction and are arranged in a second direction. Each finger is provided with a base portion, a base arc portion and a top arc portion, the base portion being arranged on the cell piece, the base arc portion and the top arc portion extending out from the base portion in the thickness direction of the cell piece, and the base arc portion being separately connected to the base portion and the top arc portion and being recessed towards the center of a section of the finger. The base arc portions are configured to be in contact connection with a circular welding strip; the circular welding strip is at least partially disposed on the base arc portions; and the circumferential arc of the circular welding strip and an arc-shaped opening of the base arc portions are consistent in direction. The back contact cell provided by the present disclosure increases the connection area between the fingers and the circular welding strip, thereby ensuring the stability and reliability of connection and avoiding stress concentration.

Description

A back-contact battery, battery string, battery module and photovoltaic system

[0001] This disclosure takes priority from the patent application filed on August 30, 2024, with application number 202411215692.1 entitled "A Back Contact Battery, Battery String, Battery Module and Photovoltaic System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure pertains to the field of solar cell technology, and particularly relates to a back-contact cell, cell string, cell module, and photovoltaic system. Background Technology

[0003] A back-contact solar cell refers to a solar cell where the light-facing side of the cell has no electrodes, and both the positive and negative electrodes are located on the back-facing side. The cell typically has a grid structure to collect and transmit current. Solder ribbons are metal strips that connect the individual cells in the solar cell; their main function is to connect the cells in series so that the current can be collected and output to an external circuit. Solder ribbons are usually soldered to the grid lines on the cell. If the connection point between the solder ribbon and the grid lines is not designed properly, it will lead to unstable connections, easily resulting in poor soldering or even breakage, thus affecting the normal transmission of current and reducing power generation efficiency. Summary of the Invention

[0004] This disclosure provides a back-contact battery, a battery string, a battery module, and a photovoltaic system, aiming to solve the problem of unstable connection caused by unreasonable design of the solder strip and grid line connection point.

[0005] This disclosure provides a back contact battery, comprising:

[0006] A solar cell, which has a front and a back side facing away from each other;

[0007] A plurality of fine grid lines are provided on the back side, extending along a first direction and arranged along a second direction. Each fine grid line has a base, a base arc portion, and a top arc portion. The base is provided on the battery cell, and the base arc portion and the top arc portion extend from the base along the thickness direction of the battery cell. The base arc portion connects the base and the top arc portion respectively and is recessed towards the structural center of the cross-section of the fine grid line. The base arc portion is used to contact and connect with a circular solder strip, which is at least partially provided on the base arc portion. The circumferential arc of the circular solder strip and the arc opening direction of the base arc portion are consistent.

[0008] Furthermore, the base arc portion includes a first base arc portion and a second base arc portion, which are respectively disposed on both sides of the top arc portion along the second direction.

[0009] Furthermore, the circular welding strip is disposed in at least one of the first base arc portion and the second base arc portion.

[0010] Furthermore, the circular welding strip includes a first welding segment and a second welding segment, with the first welding segment disposed in the first base arc portion and the second welding segment disposed in the second base arc portion.

[0011] Furthermore, the circular welding strip includes multiple first welding segments and multiple second welding segments, which are alternately arranged along a first direction.

[0012] Furthermore, the battery cell includes a first battery cell and a second battery cell. The back sides of both the first battery cell and the second battery cell are provided with a first fine grid and a second fine grid. The first fine grid and the second fine grid extend along a first direction and are alternately distributed along a second direction. The first fine grid and the second fine grid have opposite orientations, and the first direction and the second direction intersect.

[0013] A circular solder strip connects the first grid of the first solar cell and the second grid of the second solar cell.

[0014] Furthermore, the first welding segment connects to the first base arc portion of the first grid of the first battery cell, and the second welding segment connects to the second base arc portion of the second grid of the second battery cell.

[0015] Furthermore, the thickness of the fine grid lines in the thickness direction of the solar cell is 5μm-50μm.

[0016] Furthermore, the width of the fine grid lines in the second direction is 15μm-100μm.

[0017] Furthermore, the circular solder strip includes a solder strip body and a tin layer, with the tin layer wrapping around the outside of the solder strip body.

[0018] Furthermore, the diameter of the solder strip body is 0.05mm-0.5mm;

[0019] The thickness of the tin layer is 1μm-1mm.

[0020] This disclosure also provides a battery string, including a back contact battery as described in any of the above embodiments, wherein the back contact batteries are arranged along a first direction in the battery string.

[0021] Furthermore, the circular welding strip includes a first welding segment, a center coincidence point, and a second welding segment arranged sequentially;

[0022] During the fabrication of the battery string, circular solder strips extend along a third direction, and the center of the fine grid lines of the battery string coincides with the center of the corresponding circular solder strip along a first direction. The angle between the third direction and the first direction is an acute angle.

[0023] Furthermore, the first welding segment located before the center overlap point is set in the first base arc portion of the battery cell, and the second welding segment located after the center overlap point is set in the second base arc portion of the battery cell.

[0024] This disclosure also provides a battery assembly including a battery string as described in any of the above embodiments.

[0025] This disclosure also provides a photovoltaic system including the battery module described above.

[0026] This disclosure provides a back-contact battery, battery string, battery module, and photovoltaic system. By designing the fine grid lines as a base bottom, a base arc portion, and a top arc portion, and aligning the circumferential arc corresponding to the contact connection between the circular solder strip and the fine grid lines with the arc curvature direction of the base arc portion, the connection area between the circular solder strip and the fine grid lines is increased, thereby ensuring the stability and reliability of the connection and avoiding stress concentration. At the same time, the combination of the base bottom and the top arc portion enables the fine grid lines to reflect incident light at multiple angles, thereby increasing power generation efficiency. Attached Figure Description

[0027] Figure 1 is a schematic diagram of the structure of a back contact battery provided in an embodiment of this disclosure;

[0028] Figure 2 is a second schematic diagram of the structure of the back contact battery provided in an embodiment of this disclosure;

[0029] Figure 3 is a third schematic diagram of the structure of the back contact battery provided in the embodiment of this disclosure;

[0030] Figure 4 is a fourth schematic diagram of the structure of the back contact battery provided in the embodiment of this disclosure;

[0031] Figure 5 is a fifth schematic diagram of the structure of the back contact battery provided in the embodiment of this disclosure;

[0032] Figure 6 is a schematic diagram of the structure of the back contact battery provided in the embodiment of this disclosure;

[0033] Figure 7 is the seventh schematic diagram of the structure of the back contact battery provided in the embodiment of this disclosure;

[0034] Figure 8 is a schematic diagram of the structure of the circular welding strip provided in an embodiment of this disclosure;

[0035] Figure 9 is one of the structural schematic diagrams of the battery string provided in the embodiments of this disclosure;

[0036] Figure 10 is a second schematic diagram of the structure of the battery string provided in an embodiment of this disclosure;

[0037] Figure 11 is a schematic diagram of the structure of the battery assembly provided in an embodiment of this disclosure;

[0038] Figure 12 is a schematic diagram of the structure of the photovoltaic system provided in the embodiments of this disclosure.

[0039] Key component symbols: Solar cell 10; First solar cell 101; Second solar cell 102; Third solar cell 103; Fine grid line 20; Base 201; Base arc portion 202; Top arc portion 203; First base arc portion 2021; Second base arc portion 2022; First fine grid 204; Second fine grid 205; Circular solder strip 30; First welding section 301; Second welding section 302; Center overlap point 303; Solder strip body 304; Tin layer 305; Cell string 1000; Cell module 2000; Photovoltaic system 3000. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this disclosure, and should not be construed as limiting this disclosure. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this disclosure and are not intended to limit this disclosure.

[0041] In the description of this disclosure, it should be understood that the terms “length”, “width”, “upper”, “lower”, “left”, “right”, “horizontal”, “top”, “bottom”, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this disclosure 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, and therefore should not be construed as a limitation of this disclosure.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0043] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0044] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0045] The following disclosure provides numerous different embodiments or examples for implementing various structures of this disclosure. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this disclosure. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this disclosure, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0046] In related technologies, the cross-sectional shapes of grid lines include rectangular or near-rectangular, arc-shaped, or trapezoidal, etc. The design of grid lines with these cross-sectional shapes is typically based on the shading effect and optical gain of the grid lines. In the production process of solar cells, the connection between the solder ribbon and the grid lines is crucial, directly affecting the current transmission efficiency and overall performance of the solar cell module. The grid line structure in the back-contact cell provided in this disclosure can increase the connection area between the fine grid lines and the circular solder ribbon, thereby ensuring the stability and reliability of the connection and avoiding stress concentration.

[0047] The following description, in conjunction with Figures 1 to 12, details an embodiment of the present disclosure of a back-contact battery, a battery string, a battery module, and a photovoltaic system.

[0048] Figure 1 is a schematic diagram of one of the structures of a back contact battery provided in this disclosure. As shown in Figure 1, this disclosure provides a back contact battery, including:

[0049] The solar cell 10 has a front and a back side that are opposite to each other.

[0050] A plurality of fine grid lines 20 are provided on the back side, the plurality of fine grid lines 20 extending along a first direction and arranged along a second direction.

[0051] Figure 2 is a second schematic diagram of the back contact battery provided in this embodiment. As shown in Figure 2, the fine grid line 20 is formed with a base 201, a base arc portion 202, and a top arc portion 203. The base 201 is disposed on the battery cell 10. The base arc portion 202 and the top arc portion 203 extend from the base 201 along the thickness direction of the battery cell 10. The base arc portion 202 connects the base 201 and the top arc portion 203 respectively, and is recessed towards the structural center of the cross-section of the fine grid line 20. The base arc portion 202 is used to contact and connect with the circular welding strip 30. The circular welding strip 30 is at least partially disposed in the base arc portion 202. The circumferential arc of the circular welding strip 30 and the arc opening direction of the base arc portion 202 are consistent.

[0052] It should be noted that the number of solar cells 10 can be several. Several solar cells 10 can extend along a first direction, and each solar cell 10 has multiple fine grid lines 20, which also extend along the first direction and are distributed along a second direction. The solar cell 10 can be rectangular, and the first and second directions can be perpendicular. In this case, the first and second directions are also the edge directions of the solar cell 10.

[0053] As shown in Figure 1, the circular welding strip 30 is connected to the fine grid lines 20 of two adjacent battery cells 10, so that the two adjacent battery cells 10 are connected in series.

[0054] It is understood that the battery cell 10 may include two battery cells 10 connected in series, three battery cells 10 connected in series, or a greater number of battery cells 10, the specific number of battery cells 10 to be connected in series can be determined according to the actual use. In addition, in this embodiment of the disclosure, the size and type of the battery cell 10 are not limited, and the specifications and dimensions of adjacent battery cells 10 can be the same or different to meet different needs.

[0055] In this disclosure, the specific arrangement of adjacent solar cells 10 is not limited to meet different needs. In one embodiment, the edges of two adjacent solar cells 10 are at least partially stacked together; in another embodiment, two adjacent solar cells 10 may be spaced apart. A suitable spacing between two adjacent solar cells 10 can avoid insufficient operating space and difficult welding due to too small a spacing, and can also avoid wasted component space and increased costs due to too large a spacing.

[0056] The cross-sectional shape of the fine grid line 20 provided in this embodiment includes a base 201, a base arc portion 202, and a top arc portion 203. The cross-section of the fine grid line 20 refers to the cross-section where a plane perpendicular to the length extension direction of the fine grid line 20 intersects the fine grid line 20. Furthermore, the relative positions of the cross-sections of the circular solder strip 30 and the fine grid line 20 in Figure 2 are merely illustrative. In practical applications, the circular solder strip 30 and the base arc portion 202 of the fine grid line 20 will have at least partial contact connection; the larger the contact area, the more stable the connection.

[0057] The top arc 203 is arc-shaped. The arc-shaped structure can use the principle of light refraction and reflection to reintroduce some of the light that might otherwise be blocked into the solar cell, thereby increasing light absorption and reducing light loss.

[0058] The base arc portion 202 extends smoothly from both ends of the top arc portion 203 to the base bottom portion 201. The base arc portion 202 has an inwardly concave arc, and this arc is close to the arc of the circumferential arc of the circular solder strip 30. The circumferential arc refers to the arc corresponding to the contact connection between the circular solder strip 30 and the fine grid line 20. The bending direction of the base arc portion 202 is consistent with this circumferential arc, the purpose of which is to maximize the fit between the base arc portion 202 and the circumferential arc of the circular solder strip 30, so that the two have the largest possible contact area when connected. It is understood that the size of the circular solder strip 30 is not limited in this embodiment to meet different needs. In this embodiment, the size of the circular solder strip 30 can be selected to match the base arc portion 202.

[0059] The base 201 extends smoothly from the connection between the base 201 and the base arc portion 202 to the connection between the bottom surface of the fine grid line 20 and the surface of the battery cell 10. The cross-sectional shape of the fine grid line 20 formed by the base 201 and the base arc portion 202 is a curved-side trapezoid, which refers to the shape formed after the two sides of the trapezoid are replaced with arcs.

[0060] The trend of the grid line width change from the apex of the top arc portion 203 to the connection between the top arc portion 203 and the base arc portion 202 is: increasing sequentially.

[0061] The trend of the grid line width change from the connection between the top arc portion 203 and the base arc portion 202 to the connection between the base arc portion 202 and the base bottom portion 201 is: first from large to small, and then from small to large.

[0062] The trend of the grid line width from the connection between the base 201 and the base arc 202 to the surface of the cell 10 is: increasing sequentially.

[0063] Specifically, in this embodiment, the width of the top arc portion 203 from the apex to the base arc portion 202 and then to the base bottom 201 increases sequentially, but the trends of change are different. A "mountain waist" is formed in the base arc portion 202 with an arc-shaped opening direction consistent with the arc-shaped opening direction of the circular welding strip 30, resulting in a larger contact area between the base arc portion 202 and the circular welding strip 30, and a more stable connection effect.

[0064] Of course, in this embodiment, the curvature of the base arc portion 202 and the circular welding strip 30 is not limited. For circular welding strips 30 of different specifications, the size and dimensions of the base arc portion 202 can be adjusted to ensure that the base arc portion 202 and the outer surface of the circular welding strip 30 can fit together, and the connection is more stable.

[0065] Figure 3 is a third schematic diagram of the structure of the back contact battery provided in the embodiments of this disclosure.

[0066] In some embodiments, as shown in FIG3, the base arc portion 202 includes a first base arc portion 2021 and a second base arc portion 2022, which are respectively disposed on both sides of the top arc portion 203 along the second direction.

[0067] In some embodiments, the circular welding strip 30 is disposed in at least one of the first base arc portion 2021 and the second base arc portion 2022.

[0068] It is understandable that the contact position between the circular solder strip 30 and the fine grid line 20 can be set according to the actual situation, and no specific limitation is made here.

[0069] As shown in Figure 3, the circular welding strip 30 can be set in the first base arc portion 2021. That is, when the circular welding strip 30 is in contact with the fine grid line 20, the circular welding strip 30 is uniformly set on one side of the top arc portion 203 along the second direction.

[0070] As shown in Figure 2, the circular welding strip 30 can also be set in the second base arc portion 2022. That is, when the circular welding strip 30 is in contact with the fine grid line 20, the circular welding strip 30 is uniformly set on the other side of the top arc portion 203 along the second direction.

[0071] As shown in Figure 4, the circular welding strips 30 can also be disposed in the first base arc portion 2021 and the second base arc portion 2022. That is, a portion of the circular welding strips 30 is located in the first base arc portion 2021, and another portion of the circular welding strips 30 is located in the second base arc portion 2022, with the circular welding strips 30 alternately disposed in the first base arc portion 2021 and the second base arc portion 2022. Referring to Figure 4, the circular welding strips 30 located above the fine grid line 20 are all first welding segments, which connect to the first base arc portion 2021; the circular welding strips 30 located below the fine grid line 20 are all second welding segments, which connect to the second base arc portion 2022. The first welding segments and the second welding segments will be described in detail in subsequent embodiments.

[0072] As shown in Figure 5, a portion of the circular welding strips 30 are continuously disposed in the first base arc portion 2021, and another portion of the circular welding strips 30 are continuously disposed in the second base arc portion 2022.

[0073] As shown in Figure 6, a portion of the circular welding strips 30 are alternately arranged in the first base arc portion 2021 and the second base arc portion 2022, while another portion of the circular welding strips 30 can be continuously arranged in the first base arc portion 2021 or the second base arc portion 2022, without specific limitation here.

[0074] It is understood that the relative positions of the circular solder strip 30 and the fine grid line 20 in Figures 4 to 6 are only used as examples. The specific positions can be designed according to the actual situation and are not specifically limited here.

[0075] In some embodiments, as shown in FIG7, the circular welding strip 30 includes a first welding segment 301 and a second welding segment 302, the first welding segment 301 being disposed in the first base arc portion 2021, and the second welding segment 302 being disposed in the second base arc portion 2022.

[0076] It is understandable that the part of the circular weld strip 30 that contacts and connects with the first base arc portion 2021 is the first welding segment 301, and the part of the circular weld strip 30 that contacts and connects with the second base arc portion 2022 is the second welding segment 302.

[0077] Taking Figure 4 as an example, the circular weld strips 30 above the fine grid line 20 are all first weld segments 301, and the first weld segments 301 are connected to the first base arc portion 2021; the circular weld strips 30 below the fine grid line 20 are all second weld segments 302, and the second weld segments 302 are connected to the second base arc portion 2022.

[0078] In some embodiments, the circular welding strip 30 includes a plurality of first welding segments 301 and a plurality of second welding segments 302, which are alternately arranged along a first direction.

[0079] As shown in Figure 4, multiple first welding segments 301 and multiple second welding segments 302 in the circular welding strip 30 are alternately arranged along the first direction.

[0080] In some embodiments, as shown in FIG7, the battery cell 10 includes a first battery cell 101 and a second battery cell 102. The back sides of the first battery cell 101 and the second battery cell 102 are provided with a first fine grid 204 and a second fine grid 205. The first fine grid 204 and the second fine grid 205 extend along a first direction and are alternately distributed along a second direction. The first fine grid 204 and the second fine grid 205 have opposite polarities, and the first direction and the second direction intersect.

[0081] The circular welding strip 30 connects the first fine grid 204 of the first battery cell 101 and the second fine grid 205 of the second battery cell 102.

[0082] It should be noted that the fine grid lines 20 are used to collect and transmit the electrical energy generated by the first battery cell 101 and the second battery cell 102. The fine grid lines 20 located on the first battery cell 101 are called the first fine grid 204, and the fine grid lines 20 located on the second battery cell 102 are called the second fine grid 205.

[0083] In this embodiment, the positions of the circular solder strip 30 and the fine grid line 20 are not limited to meet different requirements. For example, referring to Figures 4 to 6, Figures 4 to 6 can show the positional relationship between a circular solder strip 30 and a fine grid line 20 on a solar cell 10.

[0084] In one embodiment, as shown in FIG4, the circular solder strip 30 can be alternately connected and arranged along the first direction on the upper and lower parts of the fine grid line 20. That is to say, the circular solder strip 30 has multiple first welding segments 301 and second welding segments 302, and the multiple first welding segments 301 and second welding segments 302 are respectively connected to the first base arc portion 2021 and the second base arc portion 2022 of the fine grid line 20.

[0085] In another embodiment, as shown in FIG5, the first half of the circular solder strip 30 along the first direction is a first welding segment 301 connected to the first base arc portion 2021 of the fine grid line 20, and the second half of the circular solder strip 30 along the first direction is a second welding segment 302 connected to the second base arc portion 2022 of the fine grid line 20.

[0086] In another embodiment, as shown in FIG6, the first half of the circular solder strip 30 along the first direction is alternately connected vertically to the fine grid line 20. That is, multiple first welding segments 301 and second welding segments 302 are respectively connected to the first base arc portion 2021 and the second base arc portion 2022 of the fine grid line 20. The second half of the circular solder strip 30 along the first direction is connected to the second base arc portion 2022 of the fine grid line 20 by the second welding segment 302.

[0087] Of course, the circular solder strip 30 can be disposed on both battery cells 10, that is, the circular solder strip 30 covers or partially covers the first fine grid 204 of the first battery cell 101 and the second fine grid 205 of the second battery cell 102. In this case, the circular solder strip 30 can be connected to the first fine grid 204 of the first battery cell 101 and the second fine grid 205 of the second battery cell 102 in various ways, which are not limited here, to meet different needs.

[0088] For example, as shown in Figure 4, the circular solder strip 30 can be alternately arranged on top of the first fine grid 204 located on the first battery cell 101 and the second fine grid 205 located on the second battery cell 102.

[0089] As shown in Figure 5, the circular welding strip 30 can be disposed above the first fine grid 204 of the first battery cell 101 and below the second fine grid 205 of the second battery cell 102.

[0090] As shown in Figure 6, the circular welding strip 30 can be alternately arranged above and below the first fine grid 204 located on the first battery cell 101, and arranged below the second fine grid 205 located on the second battery cell 102.

[0091] It is understandable that at the junction of the first welding section 301 and the second welding section 302, the circular welding strip 30 will come into contact with and connect to the top arc portion 203 of the fine grid line 20.

[0092] In some embodiments, as shown in FIG7, the first welding segment 301 is connected to the first base arc portion 2021 of the first fine grid 204 of the first battery cell 101, and the second welding segment 302 is connected to the second base arc portion 2022 of the second fine grid 205 of the second battery cell 102.

[0093] It should be noted that, in Figure 7, the area above the fine grid line 20 corresponds to the first base arc portion 2021, and the area below the fine grid line 20 corresponds to the second base arc portion 2022. Thus, the first welding segment 301 is in contact with the first base arc portion 2021 of the first fine grid 204 of the first battery cell 101, and the second welding segment 302 is in contact with the second base arc portion 2022 of the second fine grid 205 of the second battery cell 102.

[0094] In some embodiments, the thickness of the fine grid lines 20 in the thickness direction of the solar cell 10 is 5μm-50μm. For example, the thickness of the fine grid lines 20 in the thickness direction of the solar cell 10 is 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, or 50μm.

[0095] In practice, thicker grid lines have lower resistance, reducing current loss during transmission. However, excessively thick grid lines may increase the light-blocking area, affecting photoelectric conversion efficiency. Thinner grid lines reduce the light-blocking area, allowing more light to reach the battery surface and be converted into electrical energy. However, excessively thin grid lines may increase resistance and manufacturing difficulty. The thickness of the grid lines also affects their mechanical properties; sufficient thickness ensures that the grid lines are less prone to breakage or deformation during processing and use, thereby improving battery reliability and durability.

[0096] Taking all the above factors into consideration, the thickness of the fine gate line 20 in this embodiment is set to 5μm-50μm.

[0097] In some embodiments, the width of the fine gate line 20 in the second direction is 15μm-100μm.

[0098] In practical implementation, the width of the fine grid line 20 in the second direction is set between 15μm and 100μm. For example, the width of the fine grid line 20 in the second direction is 15μm, 30μm, 45μm, 50μm, 65μm, 80μm, 95μm, or 100μm, etc. In this embodiment, the light-shielding area of ​​the grid line is reduced, which is beneficial to improving the photoelectric conversion efficiency of the solar cell. In practical applications, the most suitable fine grid line width needs to be determined according to the specific design and manufacturing process of the solar cell, and no specific limitation is made here.

[0099] In some embodiments, as shown in FIG8, the circular solder ribbon 30 includes a solder ribbon body 304 and a tin layer 305, the tin layer 305 being wrapped around the outside of the solder ribbon body 304.

[0100] In practice, the 304 solder strip body is typically made of a highly conductive metal, such as copper or silver. These materials not only possess excellent electrical conductivity but also high mechanical strength and corrosion resistance, meeting various requirements during the welding process. The circular shape of the 304 solder strip body helps maintain stable current transmission and reduces resistance loss during welding.

[0101] The tin layer 305 tightly wraps around the outside of the solder strip body 304. This wrapping method not only enhances the conductivity of the solder strip, but also improves the connection strength between the solder strip and the object being soldered.

[0102] In some embodiments, the diameter of the solder strip body 304 is 0.05mm-0.5mm;

[0103] In practice, the diameter of the solder ribbon body 304 is 0.05mm-0.5mm, used for series welding between solar cells 10. Its small diameter and good conductivity help reduce the shading area and improve the photoelectric conversion efficiency of the photovoltaic module. The diameter of the solder ribbon body 304 can be, for example, 0.05mm, 0.1mm, 0.15mm, 0.20mm, 0.25mm, 0.30mm, 0.35mm, 0.40mm, 0.45mm, or 0.5mm.

[0104] It should be noted that the diameter of the circular solder strip 30 is larger than the diameter of the fine grid line 20.

[0105] In some embodiments, the thickness of the tin layer 305 is 1 μm-1 mm.

[0106] In actual implementation, the thickness of the tin layer 305 is 1μm-1mm. Preferably, the thickness of the tin layer 305 can be set to 1μm-20μm. Of course, it can be set to other thicknesses within the range of 1μm-1mm, which are not specifically limited here.

[0107] The back contact battery provided in this embodiment of the present disclosure increases the connection area between the circular solder strip and the fine grid line by designing the fine grid line as a base bottom, a base arc portion and a top arc portion, and making the circumferential arc corresponding to the contact connection between the circular solder strip and the fine grid line consistent with the arc bending direction of the base arc portion. This ensures the stability and reliability of the connection and avoids stress concentration. At the same time, the combination of the base bottom and the top arc portion enables the fine grid line to reflect incident light at multiple angles, thereby increasing the power generation efficiency.

[0108] Figure 9 is one of the structural schematic diagrams of the battery string provided in the embodiments of this disclosure.

[0109] As shown in Figure 9, this embodiment of the present disclosure also provides a battery string 1000, including the back contact battery as in any of the above embodiments, wherein a plurality of back contact batteries are arranged along a first direction in the battery string 1000.

[0110] It should be noted that the back contact battery has been described in detail in the above embodiments with reference to Figures 1 to 8, and will not be repeated here.

[0111] In practice, two or more back contact batteries can be arranged along the first direction. The specific number of back contact batteries to be arranged can be determined according to the actual usage. In addition, in this embodiment, the size and type of the back contact batteries are not limited. Adjacent back contact batteries can have the same or different specifications and dimensions to meet different needs.

[0112] As shown in Figure 10, each back contact battery in Figure 10 includes several battery cells 10, such as: first battery cell 101, second battery cell 102 and third battery cell 103, etc.

[0113] In this disclosure, the specific arrangement of adjacent back contact batteries is not limited to meet different needs. In one embodiment, the edges of two adjacent back contact batteries are at least partially stacked together; in another embodiment, two adjacent back contact batteries can be spaced apart. A suitable spacing between two adjacent back contact batteries can avoid insufficient operating space and difficult soldering due to too small a spacing, and can also avoid wasted component space and increased costs due to too large a spacing.

[0114] In some embodiments, the circular welding strip 30 includes a first welding segment 301, a center coincidence point 303, and a second welding segment 302 arranged sequentially.

[0115] During the fabrication of the battery string 1000, the circular solder strip 30 extends along a third direction, and the center position of the fine grid line 20 of the battery string along the first direction coincides with the center point 303 of the corresponding circular solder strip 30, wherein the included angle between the third direction and the first direction is an acute angle.

[0116] In the battery string 1000 of this embodiment, the first direction and the second direction can be vertical. In this case, the back contact battery can be rectangular, and the first direction and the second direction are also the edge directions of the back contact battery, so as to maximize the utilization of the area of ​​the back contact battery.

[0117] The circular solder strip 30 is disposed in a third direction on at least two back contact cells, as shown in Figure 10. The circular solder strip 30 is electrically connected to the fine grid line 20 of the first cell 101 and the fine grid line 20 of the adjacent second cell 102.

[0118] Circular solder strips 30 are alternately distributed in the second direction, with an acute angle between the first and third directions. By setting the circular solder strips 30 and the fine grid lines 20 at an acute angle, the contact area between the circular solder strips 30 and the first and second solar cells 101 is significantly increased, thereby improving the electrical contact area between the circular solder strips 30 and the battery doping layer and enhancing conductivity. Simultaneously, the inclined design of the circular solder strips 30 effectively alleviates stress concentration problems, ensuring the stability of the connection between the circular solder strips 30 and the back contact cells, and reducing connection failures caused by mechanical stress or temperature changes. The robust connection between the circular solder strips 30 and the battery doping layer ensures a stable electrical connection between adjacent back contact cells, improving the reliability and lifespan of the battery string.

[0119] In some embodiments, a first welding segment 301 located before the center coincidence point 303 is provided in the first base arc portion 2021 of the battery cell 10, and a second welding segment 302 located after the center coincidence point 303 is provided in the second base arc portion 2022 of the battery cell 10.

[0120] It is understood that in Figure 10, the lower part of the fine grid line 20 corresponds to the first base arc portion 2021, and the upper part of the fine grid line 20 corresponds to the second base arc portion 2022. Therefore, the first welding segment 301 is in contact with the first base arc portion 2021 of the first fine grid line 204, and the second welding segment 302 is in contact with the second base arc portion 2022 of the second fine grid line 205.

[0121] In this embodiment of the disclosure, the circular welding strip 30 and the fine grid line 20 are inclined at an acute angle, which can reduce the process difficulty of battery string, reduce the alignment requirements in the welding process, improve the fault tolerance and accuracy of welding, and reduce the manufacturing complexity.

[0122] The tilted design facilitates the operation of automated equipment, improves production efficiency, reduces manual intervention, and lowers production costs. The acute-angle tilted solder strip design helps to disperse mechanical stress, reduce stress concentration at the welding point, and improve the reliability and durability of the welding point. It also increases the connection area between the circular solder strip 30 and the fine grid line 20, ensuring the stability and reliability of the connection. Furthermore, the fine grid line 20 has the function of reflecting incident light at multiple angles, thereby increasing power generation efficiency.

[0123] In one example, nine solar cells 10 are arranged along a first direction, and circular solder ribbons 30 connect the nine solar cells 10 together. At this point, the center overlap point 303 of the circular solder ribbons 30 is located in the middle of the fifth solar cell 10. After the circular solder ribbons 30 are cut at predetermined positions using methods such as laser cutting, a battery string 1000 can be formed. In this battery string 1000, the circular solder ribbons 30 corresponding to the first four solar cells 10 are all located at the first base arc portion 2021 of the fine grid line 20; that is, the circular solder ribbons 30 corresponding to the first four solar cells 10 each have only a first welding segment 301. The first half of the circular solder ribbon 30 corresponding to the fifth solar cell 10 is the first welding segment 301, and the second half of the circular solder ribbon 30 is the second welding segment 302. The circular welding strips 30 corresponding to the last four battery cells 10 are all located in the second base arc portion 2022 of the fine grid line 20. That is to say, the circular welding strips 30 corresponding to the last four battery cells 10 all have only the second welding segment 302.

[0124] In another example, eight solar cells 10 are arranged along a first direction, and circular solder ribbons 30 connect the eight solar cells 10 together. In this case, the center overlap point 303 of the circular solder ribbons 30 is located between the fourth and fifth solar cells 10. After the circular solder ribbons 30 are cut at predetermined positions using methods such as laser cutting, a battery string 1000 can be formed. In this battery string 1000, the circular solder ribbons 30 corresponding to the first four solar cells 10 are all located at the first base arc portion 2021 of the fine grid line 201; that is, the circular solder ribbons 30 corresponding to the first four solar cells 10 each have only a first welding segment 301. The circular solder ribbons 30 corresponding to the last four solar cells 10 are all located at the second base arc portion 2022 of the fine grid line 201; that is, the circular solder ribbons 30 corresponding to the last four solar cells 10 each have only a second welding segment 302.

[0125] Figure 11 is a schematic diagram of the structure of the battery assembly provided in an embodiment of this disclosure.

[0126] As shown in Figure 11, this disclosure also provides a battery assembly 2000, including the battery string as described in any of the above embodiments.

[0127] It should be noted that the battery string has been described in detail in the above embodiments with reference to Figures 1 to 10, and will not be repeated here.

[0128] It is understood that the battery module 2000 may also include a frame, backsheet, photovoltaic glass, and encapsulant film. The encapsulant film can be filled between the front and back of the back contact cells, as well as between the photovoltaic glass and adjacent back contact cells. As a filler, it can be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulant film can be EVA film or POE film, and the specific choice can be made according to the actual situation, without limitation.

[0129] Photovoltaic glass can be applied to the encapsulating film on the front side of the back contact battery. This photovoltaic glass can be ultra-clear glass, possessing high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can achieve a light transmittance of over 92%, protecting the back contact battery while minimizing impact on its efficiency. Simultaneously, the encapsulating film bonds the photovoltaic glass and the back contact battery together, providing sealing, insulation, and waterproofing / moisture protection for the battery.

[0130] The backsheet can be attached to the adhesive film on the back of the back contact cell. The backsheet protects and supports the back contact cell, providing reliable insulation, water resistance, and aging resistance. Multiple backsheet options are available, typically including tempered glass, acrylic glass, aluminum alloy TPT composite adhesive film, etc., and the specific choice depends on the specific circumstances and is not limited here. The backsheet, back contact cell, adhesive film, and photovoltaic glass together can be mounted on the frame. The frame serves as the main external support structure for the entire battery module, providing stable support and installation. For example, the battery module can be installed at the desired location via the frame.

[0131] Figure 12 is a schematic diagram of the structure of the photovoltaic system provided in the embodiments of this disclosure.

[0132] As shown in Figure 12, this disclosure also provides a photovoltaic system 3000, including the battery module as described in any of the above embodiments.

[0133] It should be noted that the battery assembly has been described in detail in the above embodiments with reference to Figures 1 to 11, and will not be repeated here.

[0134] In this embodiment, the photovoltaic system 3000 can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to equipment or devices that utilize solar energy for power generation, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system 3000 are not limited to these; that is, the photovoltaic system 3000 can be applied in all fields that require solar energy for power generation. Taking a photovoltaic power generation system grid as an example, the photovoltaic system 3000 may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0135] In the description of this specification, references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0136] It is understood that those skilled in the art can combine various implementation methods in the above embodiments under the guidance of the above examples to obtain technical solutions with multiple implementation methods.

[0137] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A back-contact battery, comprising: A solar cell having a front and a back side facing away from each other; A plurality of fine grid lines are disposed on the back side, the fine grid lines extending along a first direction and arranged along a second direction. Each fine grid line has a base, a base arc portion, and a top arc portion. The base is disposed on the battery cell, and the base arc portion and the top arc portion extend from the base along the thickness direction of the battery cell. The base arc portion connects the base and the top arc portion respectively and is recessed towards the structural center of the cross-section of the fine grid line. The base arc portion is used for contact connection with a circular solder strip, and the circular solder strip is at least partially disposed on the base arc portion. The circumferential arc of the circular solder strip and the arc opening direction of the base arc portion are consistent.

2. The back contact battery according to claim 1, wherein, The base arc portion includes a first base arc portion and a second base arc portion, wherein the first base arc portion and the second base arc portion are respectively disposed on both sides of the top arc portion along the second direction.

3. The back contact battery according to claim 2, wherein, The circular welding strip is disposed in at least one of the first base arc portion and the second base arc portion.

4. The back contact battery according to claim 3, wherein, The circular welding strip includes a first welding segment and a second welding segment, wherein the first welding segment is disposed in the first base arc portion and the second welding segment is disposed in the second base arc portion.

5. The back contact battery according to claim 4, wherein, The circular welding strip includes a plurality of first welding segments and a plurality of second welding segments, which are alternately arranged along the first direction.

6. The back contact battery according to claim 4, wherein, The battery cell includes a first battery cell and a second battery cell. The back of both the first battery cell and the second battery cell are provided with a first fine grid and a second fine grid. The first fine grid and the second fine grid extend along the first direction and are alternately distributed along the second direction. The first fine grid and the second fine grid have opposite polarities, and the first direction and the second direction intersect. The circular solder strip connects the first fine grid of the first battery cell and the second fine grid of the second battery cell.

7. The back contact battery according to claim 6, wherein, The first welding segment is connected to the first base arc portion of the first fine grid of the first battery cell, and the second welding segment is connected to the second base arc portion of the second fine grid of the second battery cell.

8. The back contact battery according to claim 1, wherein, The thickness of the fine grid lines in the thickness direction of the solar cell is 5μm-50μm.

9. The back contact battery according to claim 1, wherein, The width of the fine grid line in the second direction is 15μm-100μm.

10. The back contact battery according to claim 1, wherein, The circular solder strip includes a solder strip body and a tin layer, with the tin layer wrapping around the outside of the solder strip body.

11. The back contact battery according to claim 10, wherein, The diameter of the welding strip body is 0.05mm-0.5mm; The thickness of the tin layer is 1μm-1mm.

12. A battery string, wherein, Includes the back contact battery as described in any one of claims 1-11, wherein the back contact batteries are arranged along the first direction in the battery string.

13. The battery string according to claim 12, wherein, The circular welding strip includes a first welding segment, a center coincidence point, and a second welding segment arranged sequentially. During the fabrication of the battery string, the circular solder strip extends along a third direction, and the center position of the fine grid line of the battery string along the first direction coincides with the center point of the corresponding circular solder strip, wherein the included angle between the third direction and the first direction is an acute angle.

14. The battery string according to claim 13, wherein, The first welding segment located before the center coincidence point is disposed on the first base arc portion of the battery cell, and the second welding segment located after the center coincidence point is disposed on the second base arc portion of the battery cell.

15. A battery assembly, wherein, Includes the battery string as described in any one of claims 12-14.

16. A photovoltaic system, wherein, Includes the battery assembly as described in claim 15.

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