Back contact battery, battery string, battery assembly and photovoltaic system

Abstract

The invention is suitable for the technical field of solar cells, and provides a back contact cell, a cell string, a cell assembly and a photovoltaic system. The back contact battery comprises a battery piece which is provided with a front surface and a back surface which are opposite to each other; the thin grid lines are arranged on the back face, extend in the first direction and are arranged in the second direction, a base part, a base arc part and a top arc part are formed on the thin grid lines, the base part is arranged on the battery piece, the base arc part and the top arc part extend out from the base part in the thickness direction of the battery piece, the base arc part is connected with the base part and the top arc part, and the top arc part is connected with the top arc part. The thin grid lines are recessed back towards the structural center direction of the sections of the thin grid lines; the base arc part is used for being in contact connection with a circular welding strip, the circular welding strip is at least partially arranged on the base arc part, and the circumferential arc of the circular welding strip and the arc opening direction of the base arc part are consistent. According to the back contact battery provided by the invention, the connection area of the fine grid lines and the circular welding strips is increased, so that the connection stability and reliability are ensured, and stress concentration is avoided.

Description

Technical Field

[0001] The present application belongs to the technical field of solar cells, and in particular to a back-contact cell, a cell string, a cell assembly and a photovoltaic system. Background Art

[0002] Back contact cells refer to solar cells with no electrodes on the light-facing side of the cell, and both the positive and negative electrodes are arranged on the backlight side of the cell. A grid structure is usually designed on the cell to collect and transmit current. The welding ribbon is a metal strip that connects the individual cells in the cell. Its main function is to connect the individual cells in series so that the current can be collected and output to the external circuit. The welding ribbon is usually welded to the grid wire on the cell. If the connection point between the welding ribbon and the grid wire is not designed properly, the connection between the welding ribbon and the grid wire will be unstable, prone to cold welding, or even disconnection, thereby affecting the normal transmission of current and reducing power generation efficiency. Summary of the invention

[0003] The embodiments of the present application provide a back-contact battery, a battery string, a battery module and a photovoltaic system, which aim to solve the problem of unstable connection caused by unreasonable design of the connection point between the write-only welding strip and the grid line.

[0004] The present application provides a back contact battery, comprising:

[0005] A battery cell, wherein the battery cell has a front side and a back side facing each other;

[0006] A plurality of fine grid lines are arranged on the back side, the plurality of fine grid lines extend along a first direction and are arranged along a second direction, the fine grid lines are formed with a base portion, a base arc portion and a top arc portion, the base portion is arranged on the battery cell, the base arc portion and the top arc portion extend from the base portion along the thickness direction of the battery cell, the base arc portion respectively connects the base portion and the top arc portion, and is concave toward the structural center direction of the cross-section of the fine grid lines; the base arc portion is used for contacting and connecting with a circular welding strip, the circular welding strip is at least partially arranged on the base arc portion, and the circumferential arc of the circular welding strip is consistent with the arc opening direction of the base arc portion.

[0007] Furthermore, the base arc portion includes a first base arc portion and a second base arc portion, and the first base arc portion and the second base arc portion are respectively arranged on both sides of the top arc portion along the second direction.

[0008] Furthermore, the circular welding strip is arranged on the first base arc portion and / or the second base arc portion.

[0009] Furthermore, the circular welding strip includes a first welding section and a second welding section, the first welding section is arranged on the first base arc portion, and the second welding section is arranged on the second base arc portion.

[0010] Furthermore, the circular welding strip includes a plurality of the first welding segments and a plurality of the second welding segments, and the plurality of the first welding segments and the plurality of the second welding segments are alternately arranged along the first direction.

[0011] Furthermore, the battery cell comprises a first battery cell and a second battery cell, the back sides of the first battery cell and the second battery cell are both 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, wherein the first fine grid and the second fine grid have opposite properties, and the first direction and the second direction intersect;

[0012] The circular welding strip connects the first fine grid of the first battery cell and the second fine grid of the second battery cell.

[0013] Furthermore, the first welding section is connected to the first base arc portion of the first fine grid of the first battery cell, and the second welding section is connected to the second base arc portion of the second fine grid of the second battery cell.

[0014] Furthermore, the thickness of the thin grid line in the thickness direction of the battery cell is 5 μm-50 μm.

[0015] Furthermore, the width of the fine gate line in the second direction is 15 μm-100 μm.

[0016] Furthermore, the circular solder strip includes a solder strip body and a tin layer, and the tin layer is wrapped around the outside of the solder strip body.

[0017] Furthermore, the diameter of the welding strip body is 0.05mm-0.5mm;

[0018] The thickness of the tin layer is 1 μm-1 mm.

[0019] An embodiment of the present application further provides a battery string, comprising the back-contact batteries as described in any of the above embodiments, wherein the back-contact batteries in the battery string are arranged along the first direction.

[0020] Furthermore, the circular welding strip includes a first welding section, a center coincidence point and a second welding section which are arranged in sequence;

[0021] During the preparation of the battery string, the circular welding strip is extended 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 coincidence point of the corresponding circular welding strip, wherein the angle between the third direction and the first direction is an acute angle.

[0022] Furthermore, the first welding section located before the center overlap point is arranged at a first base arc portion of the battery cell, and the second welding section located after the center overlap point is arranged at a second base arc portion of the battery cell.

[0023] An embodiment of the present application also provides a battery assembly, comprising a battery string as described in any of the above embodiments.

[0024] An embodiment of the present application also provides a photovoltaic system, comprising the battery assembly as described above.

[0025] The present application provides a back-contact cell, cell string, cell module and photovoltaic system, in which the fine grid wire is designed to be a base portion, a base arc portion and a top arc portion, and the circular arc corresponding to the contact connection between the circular welding strip and the fine grid wire is made consistent with the arc bending direction of the base arc portion, so that the connection area between the circular welding strip and the fine grid wire is increased, thereby ensuring the stability and reliability of the connection and avoiding stress concentration; at the same time, the base portion and the top arc portion are combined to enable the fine grid wire to reflect the incident light at multiple angles, thereby increasing the power generation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is one of the structural schematic diagrams of the back contact battery provided in the embodiments of the present application;

[0027] Figure 2 This is the second structural schematic diagram of the back contact battery provided in the embodiment of the present application;

[0028] Figure 3 This is the third structural schematic diagram of the back contact battery provided in the embodiment of the present application;

[0029] Figure 4 This is the fourth structural schematic diagram of the back contact battery provided in the embodiment of the present application;

[0030] Figure 5 This is the fifth structural schematic diagram of the back contact battery provided in the embodiment of the present application;

[0031] Figure 6 This is the sixth structural schematic diagram of the back contact battery provided in the embodiment of the present application;

[0032] Figure 7 This is the seventh structural schematic diagram of the back contact battery provided in the embodiment of the present application;

[0033] Figure 8 It is a schematic diagram of the structure of a circular welding strip provided in an embodiment of the present application;

[0034] Fig. 9 It is one of the structural schematic diagrams of the battery string provided in the embodiment of the present application;

[0035] Fig.10This is the second structural schematic diagram of the battery string provided in the embodiment of the present application;

[0036] Fig.11 is a schematic diagram of the structure of a battery assembly provided in an embodiment of the present application;

[0037] Fig.12 It is a schematic diagram of the structure of the photovoltaic system provided in the embodiment of the present application.

[0038] Description of main component symbols:

[0039] Solar cell 10; first solar cell 101; second solar cell 102; third solar cell 103; fine grid line 20; base portion 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 welding strip 30; first welding section 301; second welding section 302; center overlap point 303; welding strip body 304; tin layer 305; solar cell string 1000; solar cell assembly 2000; photovoltaic system 3000. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below 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 throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0041] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0042] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0043] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0045] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed in itself. In addition, the various specific processes and examples of materials provided by the present application, but those of ordinary skill in the art can be aware of the application of other processes and / or the use scenarios of other materials.

[0046] In the related art, the cross-sectional shapes of the grid wires are as follows: rectangular or approximately rectangular, arc-shaped or trapezoidal, etc. The design of the grid wires with the above cross-sectional shapes is usually based on the shading effect and optical gain of the grid wires. In the production process of solar cells, the connection between the welding strip and the grid wire is crucial, which is directly related to the current transmission efficiency and overall performance of the solar cell module. The grid wire structure in the back-contact battery provided in the present application can increase the connection area between the thin grid wire and the circular welding strip, thereby ensuring the stability and reliability of the connection and avoiding stress concentration.

[0047] Combine the following Figures 1 to 12 A back-contact cell, a cell string, a cell assembly and a photovoltaic system provided in the embodiments of the present application are described in detail.

[0048] Figure 1This is one of the schematic diagrams of the structure of the back contact battery provided in the embodiment of the present application. Figure 1 As shown, the present application provides a back contact battery, comprising:

[0049] The battery cell 10 has a front side and a back side facing each other.

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

[0051] Figure 2 This is the second structural diagram of the back contact battery provided in the embodiment of the present application. Figure 2 As shown, the fine grid line 20 is formed with a base portion 201, a base arc portion 202 and a top arc portion 203, the base portion 201 is arranged on the battery cell 10, the base arc portion 202 and the top arc portion 203 extend from the base portion 201 along the thickness direction of the battery cell 10, the base arc portion 202 connects the base portion 201 and the top arc portion 203 respectively, and is concave toward the structural center direction 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 arranged on the base arc portion 202, and the circumferential arc of the circular welding strip 30 is consistent with the arc opening direction of the base arc portion 202.

[0052] It should be noted that there may be a plurality of battery cells 10. A plurality of battery cells 10 may extend along a first direction, and each battery cell 10 may have a plurality of fine grid lines 20, and the plurality of fine grid lines 20 also extend along the first direction and are distributed along a second direction. The battery cell 10 may be rectangular, and the first direction and the second direction may be vertical directions, in which case the first direction and the second direction are also edge directions of the battery cell 10.

[0053] like Figure 1 As shown, the circular welding strips 30 are respectively in contact with and 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 understandable that the battery cell 10 may include two battery cells 10 connected in series, three battery cells 10 connected in series, or other larger numbers of battery cells 10, and the number of battery cells 10 to be connected in series may be determined based on actual usage. In addition, in the embodiment of the present application, the size and type of the battery cell 10 are not limited, and the specifications and sizes of adjacent battery cells 10 may be the same or different to meet different needs.

[0055] In the embodiment of the present application, the specific arrangement of adjacent battery cells 10 is not limited to meet different needs. In one embodiment, the edges of two adjacent battery cells 10 are at least partially stacked together; in another embodiment, two adjacent battery cells 10 can be arranged at intervals. The spacing between two adjacent battery cells 10 is within a suitable range, which can avoid the small operating space and high welding difficulty caused by too small spacing, and can also avoid the waste of component space and increased costs caused by too large spacing.

[0056] The cross-sectional shape of the fine gate line 20 provided in the embodiment of the present application includes a base portion 201, a base arc portion 202 and a top arc portion 203. The cross-sectional shape of the fine gate line 20 refers to the cross-sectional shape where a plane perpendicular to the length extension direction of the fine gate line 20 intersects with the fine gate line 20. In addition, Figure 2 The relative positions of the cross sections of the circular welding strip 30 and the thin grid line 20 are only used as examples. In actual applications, the circular welding strip 30 and the base arc portion 202 of the thin grid line 20 will have at least partial contact connection. The larger the contact area, the more stable the connection between the two.

[0057] The top arc portion 203 is in an arc shape. The arc-shaped structure can utilize the principles of light refraction and reflection to reintroduce part of the light that may have been shielded into the interior of the solar cell, thereby increasing light absorption and reducing light loss.

[0058] The base arc portion 202 extends smoothly to the base portion 201 along both ends of the top arc portion 203, and the base arc portion 202 has an inwardly concave curvature, and the curvature is close to the curvature of the circumferential arc of the circular welding strip 30. Among them, the circumferential arc refers to the circular arc corresponding to the contact and connection between the circular welding strip 30 and the fine grid line 20, and the bending direction of the base arc portion 202 is consistent with the circumferential arc, the purpose is to make the base arc portion 202 fit the circumferential arc of the circular welding strip 30 to the greatest extent, so that the two have as large a contact area as possible when connected. It can be understood that in the embodiment of the present application, the size of the circular welding strip 30 is not limited to meet different needs. In the embodiment of the present application, the selection of the size of the circular welding strip 30 can be coordinated with the base arc portion 202.

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

[0060] The variation trend of the gate line width 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 in sequence.

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

[0062] The change trend of the gate line width from the connection point between the base portion 201 and the base arc portion 202 to the surface of the battery cell 10 is: increasing in sequence.

[0063] Specifically, in the embodiment of the present application, the width of the top arc portion 203 from the vertex to the base arc portion 202 to the base portion 201 increases successively, but the change trend is different. A "mountainside" is formed in the base arc portion 202, the opening direction of the arc being consistent with the opening direction of the arc of the circular welding strip 30, so that the contact area between the base arc portion 202 and the circular welding strip 30 is larger, and a more stable connection effect is achieved.

[0064] Of course, in the embodiment of the present application, there is no limitation on the size of the curvature of the base arc portion 202 and the circular welding strip 30. 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 be embedded together, and the connection is more stable.

[0065] Figure 3 This is the third structural schematic diagram of the back contact battery provided in the embodiment of the present application.

[0066] In some embodiments, Figure 3 As shown, the base arc portion 202 includes a first base arc portion 2021 and a second base arc portion 2022 , and the first base arc portion 2021 and the second base arc portion 2022 are respectively arranged on both sides of the top arc portion 203 along the second direction.

[0067] In some embodiments, the circular welding strip 30 is disposed on the first base arc portion 2021 and / or the second base arc portion 2022 .

[0068] It is understandable that the contact position between the circular welding strip 30 and the thin grid line 20 can be set according to actual conditions and is not specifically limited here.

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

[0070] like Figure 2 As shown, the circular welding strip 30 can also be arranged on 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 arranged on the other side of the top arc portion 203 along the second direction.

[0071] like Figure 4As shown, the circular welding strip 30 can also be arranged at the first base arc portion 2021 and the second base arc portion 2022, that is, a part of the circular welding strip 30 is located at the first base arc portion 2021, and another part of the circular welding strip 30 is located at the second base arc portion 2022, and the circular welding strip 30 is alternately arranged at the first base arc portion 2021 and the second base arc portion 2022. Figure 4 The circular welding strips 30 located above the thin grid lines 20 are all first welding sections, which are connected to the first base arc portion 2021; the circular welding strips 30 located below the thin grid lines 20 are all second welding sections, which are connected to the second base arc portion 2022. The first welding section and the second welding section will be described in detail in subsequent embodiments.

[0072] like Figure 5 As shown, a portion of the circular welding strip 30 is continuously arranged on the first base arc portion 2021 , and another portion of the circular welding strip 30 is continuously arranged on the second base arc portion 2022 .

[0073] like Figure 6 As shown, 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, and 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, which is not specifically limited here.

[0074] It is understandable that in Figures 4 to 6 In the figure, the relative positions of the circular welding strip 30 and the thin grid line 20 are only used as examples, and the specific setting positions can be designed according to actual conditions and are not specifically limited here.

[0075] In some embodiments, Figure 7 As shown, the circular welding strip 30 includes a first welding segment 301 and a second welding segment 302 . The first welding segment 301 is arranged on the first base arc portion 2021 , and the second welding segment 302 is arranged on the second base arc portion 2022 .

[0076] It can be understood that the portion of the circular welding strip 30 that is in contact with the first base arc portion 2021 is the first welding section 301 , and the portion of the circular welding strip 30 that is in contact with the second base arc portion 2022 is the second welding section 302 .

[0077] by Figure 4 For example, the circular welding strip 30 located above the fine grid line 20 is the first welding section 301, and the first welding section 301 is connected to the first base arc portion 2021; the circular welding strip 30 located below the fine grid line 20 is the second welding section 302, and the second welding section 302 is 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 , and the plurality of first welding segments 301 and the plurality of second welding segments 302 are alternately arranged along a first direction.

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

[0080] In some embodiments, Figure 7 As shown, 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 both 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 ribbon 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 electric energy generated by the first battery cell 101 and the second battery cell 102. The fine grid lines 20 located in the first battery cell 101 are the first fine grids 204, the fine grid lines 20 located in the first battery cell 101 are the first fine grids 204, and the fine grid lines 20 located in the second battery cell 102 are the second fine grids 205.

[0083] In the embodiment of the present application, the positions of the circular welding strip 30 and the thin grid line 20 are not limited to meet different requirements. Figures 4 to 6 , Figures 4 to 6 The figure shows the positional relationship between a circular welding strip 30 and a thin grid line 20 on a battery cell 10 .

[0084] In one embodiment, Figure 4 As shown, the circular welding strip 30 can be alternately connected and arranged above and below the fine grid line 20 along the first direction, that is, the circular welding strip 30 has multiple sections of first welding sections 301 and second welding sections 302, and the multiple sections of first welding sections 301 and second welding sections 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, Figure 5 As shown, the first half of the circular welding strip 30 along the first direction is the first welding section 301 connected to the first base arc portion 2021 of the fine grid line 20, and the second half of the circular welding strip 30 along the first direction is the second welding section 302 connected to the second base arc portion 2022 of the fine grid line 20.

[0086] In yet another embodiment, Figure 6 As shown, the first half of the circular welding strip 30 along the first direction is alternately connected to the upper and lower parts of the thin grid line 20, that is, the first welding sections 301 and the second welding sections 302 are respectively connected to the first base arc portion 2021 and the second base arc portion 2022 of the thin grid line 20. The second half of the circular welding strip 30 along the first direction is the second welding section 302 connected to the second base arc portion 2022 of the thin grid line 20.

[0087] Of course, the circular welding strip 30 can be arranged on two battery cells 10, that is, the circular welding 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. At this time, the circular welding strip 30 and the first fine grid 204 of the first battery cell 101 and the second fine grid 205 of the second battery cell 102 have a variety of connection modes, which are not specifically limited here, so as to meet different needs.

[0088] For example, Figure 4 As shown, the circular welding strips 30 may be alternately arranged above and below the first fine grids 204 located on the first battery cell 101 and the second fine grids 205 located on the second battery cell 102 .

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

[0090] like Figure 6 As shown, the circular welding strips 30 may be alternately arranged above and below the first fine grids 204 located on the first battery cell 101 , and arranged below the second fine grids 205 located on the second battery cell 102 .

[0091] It can be understood that at the junction of the first welding section 301 and the second welding section 302 , the circular welding strip 30 will be in contact with and connected to the top arc portion 203 of the thin grid line 20 .

[0092] In some embodiments, Figure 7 As shown, the first welding section 301 connects the first base curve portion 2021 of the first fine grid 204 of the first battery cell 101 , and the second welding section 302 connects the second base curve portion 2022 of the second fine grid 205 of the second battery cell 102 .

[0093] It should be noted that Figure 7The upper part of the middle fine grid line 20 corresponds to the first base curve portion 2021, and the lower part of the fine grid line 20 corresponds to the second base curve portion 2022. The first welding section 301 is in contact and connected with the first base curve portion 2021 of the first fine grid 204 of the first battery cell 101, and the second welding section 302 is in contact and connected with the second base curve portion 2022 of the second fine grid 205 of the second battery cell 102.

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

[0095] In actual implementation, thicker fine grid lines have lower resistance and can reduce the loss of current during transmission. Too thick fine grid lines may increase the shading area and affect the photoelectric conversion efficiency. Thinner fine grid lines can reduce the shading area, allowing more light to shine on the surface of the battery and be converted into electrical energy. However, too thin fine grid lines may increase resistance and processing difficulty. The thickness of the fine grid lines is also related to their mechanical properties. Sufficient thickness can ensure that the fine grid lines are not easy to break or deform during processing and use, thereby improving the reliability and durability of the battery.

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

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

[0098] In actual 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. In the embodiment of the present application, the shading area of ​​the grid line is reduced, which is beneficial to improving the photoelectric conversion efficiency of the battery cell. In practical applications, it is necessary to determine the most suitable width of the fine grid line according to the specific design and manufacturing process of the battery, which is not specifically limited here.

[0099] In some embodiments, Figure 8 As shown, the circular soldering ribbon 30 includes a soldering ribbon body 304 and a tin layer 305 , wherein the tin layer 305 is wrapped around the outside of the soldering ribbon body 304 .

[0100] In actual implementation, the welding strip body 304 is usually made of metal materials with good electrical conductivity, such as copper, silver, etc. These materials not only have good electrical conductivity, but also have high mechanical strength and corrosion resistance, and can meet various requirements in the welding process. The circular shape of the welding strip body 304 is conducive to maintaining stable current transmission during the welding process and reducing resistance loss.

[0101] The tin layer 305 is tightly wrapped around the outside of the soldering strip body 304. This wrapping method not only enhances the conductive property of the soldering strip, but also improves the connection strength between the soldering strip and the soldering object.

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

[0103] In actual implementation, the diameter of the welding ribbon body 304 is 0.05mm-0.5mm, and is used for series welding between the 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 welding 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 welding strip 30 is larger than the diameter of the thin 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 1 μm-1 mm. Preferably, the thickness of the tin layer 305 can be set to 1 μm-20 μm. Of course, it can be set to other thicknesses in the range of 1 μm-1 mm, which is not specifically limited here.

[0107] The back-contact battery provided in the embodiment of the present application increases the connection area between the circular welding strip and the fine grid wire by designing the fine grid wire into a base portion, a base arc portion and a top arc portion, and makes the circular arc corresponding to the contact connection between the circular welding strip and the fine grid wire consistent with the arc bending direction of the base arc portion, thereby ensuring the stability and reliability of the connection and avoiding stress concentration; at the same time, combined with the base portion and the top arc portion, the fine grid wire has the function of multi-angle reflection of incident light, thereby increasing the power generation efficiency.

[0108] Fig. 9 This is one of the structural schematic diagrams of the battery string provided in the embodiment of the present application.

[0109] like Fig. 9As shown, an embodiment of the present application further provides a battery string 1000, comprising a back-contact battery as in any of the above embodiments, wherein a plurality of back-contact batteries in the battery string 1000 are arranged along a first direction.

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

[0111] In actual implementation, two or more back contact batteries can be arranged along the first direction, and the number of back contact batteries to be arranged can be determined according to actual usage. In addition, in the embodiment of the present application, the size and type of the back contact battery are not limited, and the specifications and sizes of adjacent back contact batteries can be the same or different to meet different needs.

[0112] like Fig.10 As shown, Fig.10 Each back contact battery includes a plurality of battery cells 10 , for example, a first battery cell 101 , a second battery cell 102 , and a third battery cell 103 .

[0113] In the embodiments of the present application, the specific arrangement of adjacent back contact cells is not limited to meet different needs. In one embodiment, the edges of two adjacent back contact cells are at least partially stacked together; in another embodiment, two adjacent back contact cells can be arranged at intervals. The spacing between two adjacent back contact cells is within a suitable range, which can avoid the small operating space and high welding difficulty caused by too small spacing, and can also avoid the waste of component space and increased costs caused by too large 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 that are sequentially arranged;

[0115] During the preparation of the battery string 1000, the circular welding strip 30 is extended along the third direction, and the center position of the thin grid line 20 of the battery string along the first direction coincides with the center coincidence point 303 of the corresponding circular welding strip 30, wherein the angle between the third direction and the first direction is an acute angle.

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

[0117] The circular solder strip 30 is arranged on at least two back contact cells in a third direction, such as Fig.10As shown, the circular welding strips 30 electrically connect the fine grid lines 20 of the first battery cell 101 and the fine grid lines 20 of the adjacent second battery cell 102 .

[0118] The circular welding strips 30 are alternately distributed in the second direction, wherein the angle between the first direction and the third direction is an acute angle. By tilting the circular welding strips 30 and the fine grid lines 20 at an acute angle, the contact area between the circular welding strips 30 and the first battery cell 101 and the second battery cell 102 is significantly increased, thereby increasing the electrical contact area between the circular welding strips 30 and the battery doping layer and enhancing the conductive efficiency. At the same time, the tilted design of the circular welding strips 30 can effectively alleviate the stress concentration problem, ensure the stability of the connection between the circular welding strips 30 and the back contact battery, and reduce the connection failure caused by mechanical stress or temperature changes. The firm connection between the circular welding strips 30 and the battery doping layer ensures a stable electrical connection between adjacent back contact batteries, improving the reliability and service life of the battery string.

[0119] In some embodiments, the first welding section 301 located before the center overlap point 303 is disposed on the first base curve portion 2021 of the battery cell 10 , and the second welding section 302 located after the center overlap point 303 is disposed on the second base curve portion 2022 of the battery cell 10 .

[0120] Understandably, Fig.10 The lower part of the middle thin gate line 20 corresponds to the first base curve portion 2021 , and the upper part of the thin gate line 20 corresponds to the second base curve portion 2022 . The first welding section 301 is in contact with the first base curve portion 2021 of the thin gate line 204 , and the second welding section 302 is in contact with the second base curve portion 2022 of the thin gate line 205 .

[0121] In the embodiment of the present application, the circular welding strip 30 and the thin grid line 20 are tilted at an acute angle, which can reduce the process difficulty of the battery string, reduce the positioning requirements during the welding process, improve the welding tolerance and accuracy, and reduce the manufacturing complexity.

[0122] The tilted setting makes it easier to operate automated equipment, improves production efficiency, reduces manual intervention, and reduces production costs. The sharp-angle tilted solder strip design helps to disperse mechanical stress, reduce stress concentration at solder joints, and improve the reliability and durability of solder joints; it also increases the connection area between the circular solder strip 30 and the fine grid wire 20 to ensure the stability and reliability of the connection, and the fine grid wire 20 has the function of reflecting incident light at multiple angles, thereby increasing the power generation efficiency.

[0123] In one example, 9 battery cells 10 are placed along a first direction, and the circular welding strips 30 connect the 9 battery cells 10 in series. At this time, the center overlap point 303 of the circular welding strips 30 is located in the middle of the fifth battery cell 10. After the circular welding strips 30 are cut at a predetermined position by laser or other means, a battery string 1000 can be formed. In the battery string 1000, the circular welding strips 30 corresponding to the first four battery cells 10 are all located at the first base arc portion 2021 of the fine grid line 201, that is, the circular welding strips 30 corresponding to the first four battery cells 10 have only the first welding section 301. The first half of the circular welding strip 30 corresponding to the fifth battery cell 10 is the first welding section 301, and the second half of the circular welding strip 30 is the second welding section 302. The circular welding strips 30 corresponding to the last four battery cells 10 are all located at the second base arc portion 2022 of the thin grid line 201 , that is, the circular welding strips 30 corresponding to the last four battery cells 10 only have the second welding section 302 .

[0124] In another example, eight battery cells 10 are placed along the first direction, and the circular welding strips 30 connect the eight battery cells 10 in series. At this time, the center overlap point 303 of the circular welding strips 30 is located between the fourth battery cell 10 and the fifth battery cell 10. After the circular welding strips 30 are cut at a predetermined position by laser or other means, a battery string 1000 can be formed. In the battery string 1000, the circular welding strips 30 corresponding to the first four battery cells 10 are all located at the first base arc portion 2021 of the fine grid line 201, that is, the circular welding strips 30 corresponding to the first four battery cells 10 have only the first welding section 301. The circular welding strips 30 corresponding to the last four battery cells 10 are all located at the second base arc portion 2022 of the fine grid line 201, that is, the circular welding strips 30 corresponding to the last four battery cells 10 have only the second welding section 302.

[0125] Fig.11 It is a schematic diagram of the structure of the battery assembly provided in an embodiment of the present application.

[0126] like Fig.11 As shown, an embodiment of the present application further provides a battery assembly 2000, comprising a battery string as in any of the above embodiments.

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

[0128] It is understandable that the battery assembly 2000 may also include a frame, a back plate, photovoltaic glass and an adhesive film. The adhesive film may be filled between the front and back of the back contact battery and the photovoltaic glass, adjacent back contact batteries, etc. As a filler, it may be a transparent colloid with good light transmittance and aging resistance. For example, the adhesive film may be an EVA adhesive film or a POE adhesive film. The specific selection may be based on actual conditions and is not limited here.

[0129] Photovoltaic glass can cover the adhesive film on the front of the back contact cell. The photovoltaic glass can be ultra-white glass, which has high light transmittance, high transparency, and excellent physical, mechanical and optical properties. For example, the light transmittance of ultra-white glass can reach more than 92%, which can protect the back contact cell without affecting the efficiency of the back contact cell as much as possible. At the same time, the adhesive film can bond the photovoltaic glass and the back contact cell together. The presence of the adhesive film can seal and insulate the back contact cell and prevent water and moisture.

[0130] The backplane can be attached to the film on the back of the back contact battery. The backplane can protect and support the back contact battery and has reliable insulation, water resistance and aging resistance. There are multiple options for the backplane, which can usually be tempered glass, organic glass, aluminum alloy TPT composite film, etc. The specific configuration can be made according to the specific situation and is not limited here. The whole composed of the backplane, back contact battery, film and photovoltaic glass can be set on the frame. The frame serves as the main external support structure of the entire battery assembly and can provide stable support and installation for the battery assembly. For example, the battery assembly can be installed at the required location through the frame.

[0131] Fig.12 It is a schematic diagram of the structure of the photovoltaic system provided in the embodiment of the present application.

[0132] like Fig.12 As shown, an embodiment of the present application further provides a photovoltaic system 3000, comprising a battery assembly as in any of the above embodiments.

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

[0134] In the embodiment of the present application, the photovoltaic system 3000 can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water surface power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic system 3000 are not limited to this, that is, the photovoltaic system 300 can be applied in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system 3000 may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple battery components. For example, multiple battery components may form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter to convert it into the alternating current required by the mains power grid and then connected to the mains network to realize solar power supply.

[0135] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0136] It is understandable that those skilled in the art can, under the guidance of the above embodiments, combine various implementations in the above embodiments to obtain technical solutions of multiple implementations.

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

Claims

1. A back contact battery, characterized in that: include: A battery cell, wherein the battery cell has a front side and a back side facing each other; A plurality of fine grid lines are arranged on the back side, the plurality of fine grid lines extend along a first direction and are arranged along a second direction, the fine grid lines are formed with a base portion, a base arc portion and a top arc portion, the base portion is arranged on the battery cell, the base arc portion and the top arc portion extend from the base portion along the thickness direction of the battery cell, the base arc portion respectively connects the base portion and the top arc portion, and is concave toward the structural center direction of the cross-section of the fine grid lines; the base arc portion is used for contacting and connecting with a circular welding strip, the circular welding strip is at least partially arranged on the base arc portion, and the circumferential arc of the circular welding strip is consistent with the arc opening direction of the base arc portion.

2. The back contact cell according to claim 1, characterized in that: The base arc portion includes a first base arc portion and a second base arc portion, and the first base arc portion and the second base arc portion are respectively arranged at two sides of the top arc portion along the second direction.

3. The back contact battery according to claim 2, characterized in that: The circular welding strip is arranged on the first base arc portion and / or the second base arc portion.

4. The back contact cell according to claim 3, characterized in that: The circular welding strip includes a first welding section and a second welding section. The first welding section is arranged at the first base arc portion, and the second welding section is arranged at the second base arc portion.

5. The back contact cell according to claim 4, characterized in that: The circular welding strip includes a plurality of the first welding segments and a plurality of the second welding segments, and the plurality of the first welding segments and the plurality of the second welding segments are alternately arranged along the first direction.

6. The back contact cell according to claim 4, characterized in that: The battery cell comprises a first battery cell and a second battery cell, the back sides of the first battery cell and the second battery cell are both 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, wherein the first fine grid and the second fine grid have opposite properties, and the first direction and the second direction intersect; The circular welding 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 cell according to claim 6, characterized in that: The first welding section is connected to the first base arc portion of the first fine grid of the first battery cell, and the second welding section is connected to the second base arc portion of the second fine grid of the second battery cell.

8. The back contact cell according to claim 1, characterized in that: The thickness of the thin grid line in the thickness direction of the battery cell is 5 μm-50 μm.

9. The back contact cell according to claim 1, characterized in that: The width of the fine gate line in the second direction is 15 μm-100 μm.

10. The back contact cell according to claim 1, characterized in that: The circular solder strip comprises a solder strip body and a tin layer, wherein the tin layer is wrapped around the outside of the solder strip body.

11. The back contact cell according to claim 10, characterized in that: The diameter of the welding strip body is 0.05mm-0.5mm; The thickness of the tin layer is 1 μm-1 mm.

12. A battery string, characterized in that: The method comprises a back-contact cell according to any one of claims 1 to 11, wherein the back-contact cells are arranged along the first direction in the cell string.

13. The battery string according to claim 12, characterized in that: The circular welding strip comprises a first welding section, a center coincidence point and a second welding section which are arranged in sequence; During the preparation of the battery string, the circular welding strip is extended 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 coincidence point of the corresponding circular welding strip, wherein the angle between the third direction and the first direction is an acute angle.

14. The back contact cell according to claim 13, characterized in that: The first welding section located before the center overlap point is arranged at the first base arc portion of the battery cell, and the second welding section located after the center overlap point is arranged at the second base arc portion of the battery cell.

15. A battery assembly, characterized in that: Comprising a battery string as claimed in any one of claims 12 to 14.

16. A photovoltaic system, characterized in that: Comprising the battery assembly as claimed in claim 15.

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