Back contact cells, back contact laminated cells and photovoltaic modules

Abstract

The application relates to the photovoltaic field, and provides a back contact cell, a back contact laminated cell and a photovoltaic module. The back contact cell comprises a body, the back light surface of the body is provided with a fine grid and an edge pad group; the fine grid comprises a first fine grid and a second fine grid; at least one end of the body is provided with the edge pad group along a first direction, the edge pad group is electrically connected with the first fine grid and is spaced apart from the second fine grid; the edge pad group has at least two edge pads which are spaced apart along the first direction. The adjacent edge pads are electrically connected through a first edge connecting line, and the first edge connecting line is used for transmitting current between the adjacent edge pads; if the connection between one edge pad and a solder strip fails, the current on the first fine grid of the edge region of the body can also be transmitted to the solder strip through other edge pads, so that the current loss of the back contact cell is reduced, and the output power of the back contact cell is provided.

Description

Technical Field

[0001] This application relates to the photovoltaic field, specifically to a back-contact battery, a back-contact tandem battery, and a photovoltaic module. Background Technology

[0002] In back-contact solar cells, both the positive and negative grid lines are located on the back side, leaving the light-facing side unobstructed by the grid lines. Compared to conventional photovoltaic cells, this reduces light energy loss due to grid line shading, resulting in higher photoelectric conversion efficiency. When multiple back-contact solar cells are assembled into a photovoltaic module, solder ribbons are typically used to connect the grid lines of adjacent cells.

[0003] Back-contact batteries are equipped with edge connection lines and edge pads. Current on the grid lines located at the battery edge is transmitted to the solder ribbon through the edge connection lines and edge pads. However, existing back-contact battery structures suffer from low reliability in the connection between the edge pads and the solder ribbon. If the connection between the solder ribbon and the edge pads fails, current on the grid lines located at the battery edge cannot be transmitted to the solder ribbon, resulting in a reduction in the output power of the back-contact battery. Summary of the Invention

[0004] In view of this, this application provides a back contact cell, a back contact tandem cell, and a photovoltaic module to help solve the problem of insufficient connection reliability between the edge pads and solder strips of the back contact cell in the prior art.

[0005] This application provides a back contact battery, including a body, the back surface of which is provided with a fine grid and an edge pad group; the fine grid includes a first fine grid and a second fine grid; along a first direction, at least one end of the body is provided with the edge pad group, the edge pad group is electrically connected to the first fine grid and spaced apart from the second fine grid; the edge pad group has at least two edge pads spaced apart along the first direction, and adjacent edge pads are electrically connected through a first edge connection line.

[0006] In one possible implementation, the edge pad group further includes a second edge connection line. Along the first direction, the second edge connection line is disposed at one end of the edge pad group near the edge of the body, and the second edge connection line is electrically connected to the edge pad. The width D1 of the first edge connection line is greater than the width D2 of the second edge connection line.

[0007] In one possible implementation, the widths D1 and D2 of the first edge connection line satisfy: 1.2:1 ≤ D1:D2 ≤ 2:1.

[0008] In one possible implementation, the first edge connecting line has a first sidewall and a second sidewall, the first sidewall and the second sidewall being distributed opposite to each other in the width direction of the first edge connecting line; the extension direction of the first sidewall is parallel to the extension direction of the second sidewall.

[0009] In one possible implementation, the first edge connecting line includes a middle segment and an edge segment, wherein the middle segment has the edge segment at both ends along the first direction; the maximum width of the middle segment is less than or equal to the minimum width of the edge segment.

[0010] In one possible implementation, the minimum width on the middle segment is D3, and the maximum width on the edge segment is D4, where D3 and D4 satisfy: 1:6≤D3:D4≤1:3.

[0011] In one possible implementation, the area of ​​the edge pad is greater than or equal to 0.5 mm. 2 .

[0012] In one possible implementation, the edge pad group has two edge pads, and the distance L1 between the two edge pads along the first direction satisfies: 3mm ≤ L1 ≤ 4.5mm.

[0013] In one possible implementation, the edge pads include a first edge pad and a second edge pad, with the first edge pad located at one end of the edge pad group near the body edge along the first direction, and the second edge pad located at one end of the edge pad group away from the body edge; the area of ​​the first edge pad is smaller than the area of ​​the second edge pad.

[0014] In one possible implementation, the ratio of the area of ​​the first edge pad to the area of ​​the second edge pad is 1:1.8 to 1:2.5.

[0015] This application provides a back-contact stacked battery, including a back-contact bottom battery and a perovskite top battery. The perovskite top battery is electrically connected to the light-facing surface of the back-contact bottom battery, and the back-contact bottom battery is the back-contact battery described above.

[0016] This application provides a photovoltaic module, including multiple photovoltaic cells, wherein the photovoltaic cells are back-contact cells as described above, or the photovoltaic cells are back-contact stacked cells as described above; and a solder strip, wherein two adjacent photovoltaic cells along the first direction are electrically connected by the solder strip.

[0017] The beneficial effects of this application are as follows: the first edge connection line plays a role in transmitting current between adjacent edge pads. When the edge pad group includes at least two edge pads, if the connection between one edge pad and the solder strip fails, the current on the first fine gate in the edge region of the body can still be transmitted to the solder strip through other edge pads, which helps to reduce the current loss of the back contact battery and provide the output power of the back contact battery. In electroluminescence (EL) detection, the back contact battery with the above structure will not show local black spots or dark bars caused by the failure of a single edge pad, making the EL test results of the back contact battery more uniform and reliable. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A partial structural schematic diagram of the backlight surface of the back contact battery provided in the embodiments of this application in a first embodiment; Figure 2 A partial structural schematic diagram of the backlight surface of the back contact battery provided in the embodiments of this application in a second embodiment; Figure 3 A partial structural schematic diagram of the backlight surface of the back contact battery provided in the embodiments of this application in a third embodiment; Figure 4 A partial structural schematic diagram of the backlight surface of the back contact battery provided in the embodiments of this application in the fourth embodiment; Figure 5 This is a schematic diagram of the structure of the back contact battery provided in the first embodiment of this application; Figure 6 A partial structural schematic diagram of the backlight surface of the back contact battery provided in the fifth embodiment of this application; Figure 7 A schematic diagram of the structure of the back contact battery provided in the embodiments of this application in a second embodiment; Figure 8 This is a schematic diagram of the structure of the back contact stacked battery provided in the embodiments of this application; Figure 9 This is a schematic diagram of the structure of the photovoltaic module provided in the first embodiment of this application; Figure 10 This is a schematic diagram of the structure of the photovoltaic module provided in the second embodiment of this application.

[0020] Figure label: 10-Back contact battery; 20-Back contact stacked battery; 201-Back contact bottom battery; 202-Perovskite Top Cell; 30 - Welding strip; 40-front plate; 50 - Front encapsulation layer; 60 - Backside encapsulation layer; 70-back panel; 1-Ontology; 2-Fine grid; 21-First fine grid; 21' - First positive electrode fine gate; 21" - First negative electrode fine grid; 22-Second fine grid; 22' - Second negative electrode fine gate; 22" - Second positive electrode fine grid; 3-Edge pad group; 3A - First edge pad group; 3B - Second edge pad group; 31 - Edge pads; 311 - First edge pad; 312 - Second edge pad; 32 - First edge connection line; 321 - First sidewall; 322 - Second sidewall; 323 - Middle Section; 324 - Edge segment; 33 - Second edge connection line; 331 - Third sidewall; 332 - Fourth sidewall; 4-Intermediate pads; 41 - First intermediate pad; 42 - Second intermediate pad; 5-Edge grid lines; 6-Main gate. Detailed Implementation

[0021] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0022] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0023] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0024] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0025] In the accompanying drawings corresponding to the embodiments of this application, for clarity, the proportions of structures such as layers, films, and regions may not be proportions of actual structures. It should be understood that when it is mentioned that feature a (e.g., layer, film, region, or substrate) is "located" "on" feature b, feature a may be directly located on feature b, or there may be other features c between feature a and feature b. Conversely, when it is mentioned that feature a is "directly located" "on" feature b, it means that there are no other features between feature a and feature b.

[0026] In the description of the embodiments of this application, the meaning of "electrical connection" may include: after two structures with conductive properties are physically connected, under the action of an electric field, one of the two physically connected structures with conductive properties can conduct electricity to the other. The physical connection for conducting electricity can be a direct connection or an indirect connection through other conductive media.

[0027] In the description of the embodiments of this application, the use of terms such as "same," "equal," or "consistent" regarding dimensions does not require absolute mathematical or geometric precision. Given the actual manufacturing, measurement, and material factors, those skilled in the art should understand that the aforementioned dimensional terms include deviations within permissible limits or unavoidable deviations. As long as such deviations do not affect the functionality and technical effects of the corresponding dimensions in this application, they should be considered to fall within the meaning of "same dimensions" as described in the embodiments of this application.

[0028] This application provides a back contact battery 10, such as Figure 1 As shown, the back contact battery 10 includes a body 1, and a fine grid 2 is provided on the back surface of the body 1. The fine grid 2 includes a first fine grid 21 and a second fine grid 22. Both the first fine grid 21 and the second fine grid 22 extend along the second direction Y, and are used to collect and guide the photocurrent generated in the body 1. The first fine grid 21 and the second fine grid 22 can be alternately distributed in the first direction X.

[0029] It should be noted that the first direction X intersects with the second direction Y, such as... Figure 1 As shown, one of the first direction X and the second direction Y can be the length direction of the back contact battery 10, and the other can be the width direction of the back contact battery 10.

[0030] The accompanying drawings provided in this application use lines of different thicknesses to distinguish the first fine gate 21 and the second fine gate 22. This is not a limitation on the relative width between the first fine gate 21 and the second fine gate 22. The width of the first fine gate 21 and the width of the second fine gate 22 may be equal or unequal.

[0031] like Figure 1 As shown, the back contact battery 10 also includes an edge pad group 3, which is disposed on the back surface of the body 1. Along the first direction X, at least one end of the body 1 is provided with the edge pad group 3. The edge pad group 3 and the first fine gate 21 have the same polarity and are electrically connected. That is, the edge pad group 3 is disposed in the edge region of the body 1 to collect the current on the first fine gate 21 in that edge region. Along the second direction Y, the two sides of the edge pad group 3 are respectively spaced apart from the second fine gate 22, meaning the second fine gate 22 is disconnected at the edge pad group 3, preventing a short circuit caused by the second fine gate 22 with opposite polarity being electrically connected to the edge pad group 3.

[0032] In some embodiments, such as Figure 1 As shown, the edge pad group 3 has at least two edge pads 31 spaced apart along a first direction X, and adjacent edge pads 31 are electrically connected by a first edge connection line 32. Both the edge pads 31 and the first edge connection line 32 are electrically connected to the first fine gate 21 and spaced apart from the second fine gate 22. The edge pads 31 and the first edge connection line 32 are used to collect current on the first fine gate 21 in the edge region of the body 1. The edge pads 31 are used to connect with solder strips to achieve series connection between adjacent back contact batteries 10 and to drain the current collected on the multiple first fine gates 21 by the edge pad group 3.

[0033] In this embodiment, the first edge connection line 32 serves to transmit current between adjacent edge pads 31. When the edge pad group 3 includes at least two edge pads 31, if the connection between one edge pad 31 and the solder strip fails, the current on the first fine gate 21 in the edge region of the body 1 can still be transmitted to the solder strip through other edge pads 31, which helps to reduce the current loss of the back contact battery 10 and provide the output power of the back contact battery 10. In electroluminescence (EL) detection, the back contact battery 10 with the above structure will not show local black spots or dark bars caused by the failure of a single edge pad 31, making the EL test results of the back contact battery 10 more uniform and reliable.

[0034] Specifically, when the edge pad 31 is a positive electrode pad, the first fine gate 21 is a positive electrode fine gate and the second fine gate 22 is a negative electrode fine gate; when the edge pad 31 is a negative electrode pad, the first fine gate 21 is a negative electrode fine gate and the second fine gate 22 is a positive electrode fine gate.

[0035] In some embodiments, such as Figure 1 As shown, the edge pad group 3 also includes a second edge connection line 33. Along the first direction X, the second edge connection line 33 is disposed at one end of the edge pad group 3 near the edge of the body 1, and the second edge connection line 33 is electrically connected to the edge pad 31. The second edge connection line 33 is electrically connected to the first fine gate 21 and is spaced apart from the second fine gate 22, and is used to collect the current on the first fine gate 21 in the outermost region of the body 1 (between the edge pad 31 and the end of the body 1) to improve the current collection efficiency of the back contact battery 10.

[0036] In some embodiments, such as Figure 1 As shown, the width D1 of the first edge connection line 32 is greater than the width D2 of the second edge connection line 33. The relatively larger width of the first edge connection line 32 improves its structural reliability and allows for a larger cross-sectional area, thereby reducing its resistance. This ensures that even if the connection between an edge pad 31 and the solder ribbon fails, current can be transmitted with low loss to the adjacent edge pad 31 via the first edge connection line 32. The relatively smaller width of the second edge connection line 33 reduces the amount of raw materials used, thus helping to lower the manufacturing cost of the edge pad group 3.

[0037] In some embodiments, the width D1 of the first edge connection line 32 and the width D2 of the second edge connection line 33 satisfy the following ratio: 1.2:1 ≤ D1:D2 ≤ 2:1, that is, D1 is 1.2 to 2 times D2. If D1:D2 < 1.2:1, the width D1 of the first edge connection line 32 may be insufficient, resulting in a higher resistance of the first edge connection line 32 and a tendency for local overheating. If D1:D2 > 2:1, the width D1 of the first edge connection line 32 may be too large, leading to increased manufacturing costs. Furthermore, when the first edge connection line 32 is too wide, it is prone to short-circuiting with the second fine grid 22, affecting the electrical reliability of the back contact battery 10.

[0038] Therefore, when the ratio of D1 to D2 meets the above range, it can not only improve the current collection capability of the edge pad group 3 on the first fine gate 21 of the edge region of the body 1, but also appropriately reduce the manufacturing cost of the edge pad group 3 and improve the electrical reliability of the back contact battery 10.

[0039] Optionally, D1:D2 can be 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, or other values ​​within the above range. This embodiment does not limit this.

[0040] The structure of the first edge connecting line 32 will be described below with reference to the accompanying drawings.

[0041] like Figure 1 As shown, in the first embodiment, the first edge connecting line 32 has a first sidewall 321 and a second sidewall 322. The first sidewall 321 and the second sidewall 322 are distributed opposite to each other in the width direction (second direction Y) of the first edge connecting line 32, and the extension direction of the first sidewall 321 is parallel to the extension direction of the second sidewall 322. That is, the width of the first edge connecting line 32 is uniform, thereby ensuring that the resistance of the first edge connecting line 32 is uniform in its extension direction, optimizing the current collection effect of the first edge connecting line 32, and also helping to reduce the manufacturing process difficulty of the first edge connecting line 32.

[0042] In the first embodiment described above, the width of any part on the first edge connecting line 32 is D1.

[0043] like Figure 2 As shown, in the second embodiment, the first edge connection line 32 includes a middle segment 323 and an edge segment 324. The middle segment 323 has edge segments 324 at both ends along the first direction X. The maximum width of the middle segment 323 is less than or equal to the minimum width of the edge segment 324. That is, the first edge connection line 32 has an hourglass-shaped structure that is wide at both ends and narrow in the middle along the first direction X. This structure can reduce the manufacturing cost of the first edge connection line 32 without affecting the current transmission performance of the first edge connection line 32 and the connection reliability between the first edge connection line 32 and its two end edge pads 31.

[0044] In the second embodiment described above, such as Figure 3 As shown, the widths of the middle segment 323 and the edge segments 324 at both ends can be uniform. In this case, the width of any part on the edge segment 324 is D1.

[0045] Or, such as Figure 2 As shown, the widths of the middle segment 323 and the edge segments 324 at both ends are non-uniform. The width of the middle segment 323 gradually increases from the center to both ends along its first direction X, while the width of the edge segments 324 gradually decreases along the direction close to the middle segment 323. At this time, the width of the widest part of the edge segment 324 is D1.

[0046] In the second implementation described above, the minimum width of the middle segment 323 is D3, and the maximum width of the edge segment 324 is D4. D3 and D4 satisfy the ratio: 1:6 ≤ D3:D4 ≤ 1:3, meaning D4 is 3-6 times D3. If D3:D4 < 1:6, the width D3 of the middle segment 323 may be too small, resulting in a higher resistance and affecting the current transmission between adjacent edge pads 31, leading to increased current loss. Furthermore, a too-small width D3 of the middle segment 323 increases the manufacturing difficulty and may cause breakage. If D3:D4 is greater than 1:3, the width D3 of the middle segment 323 may be too large, increasing the amount of raw materials used and thus increasing the manufacturing cost of the first edge connection line 32.

[0047] Therefore, when the ratio of D3 to D4 meets the above range, it can not only ensure the connection strength between the first edge connection line 32 and its two end edge pads 31, but also reduce the amount of raw materials used in the first edge connection line 32 and reduce the manufacturing cost of the first edge connection line 32.

[0048] Optionally, D3:D4 can be 1:6, 1:1.55, 1:1.5, 1:1.45, 1:1.4, 1:1.35 or 1:3, or other values ​​within the above range. This embodiment does not limit this.

[0049] Among them, such as Figure 3 As shown, when the widths of the middle segment 323 and the edge segments 324 at both ends are uniform, the width of any part of the middle segment 323 is D3 and the width of any part of the edge segment 324 is D4.

[0050] Or, such as Figure 2 As shown, when the widths of the middle segment 323 and the edge segments 324 at both ends are non-uniform, the narrowest width of the middle segment 323 is D3, and the widest width of the edge segments 324 is D4. In this embodiment, the width D3 of the narrowest part of the middle segment 323 is 0.05mm-0.1mm, which can ensure the structural reliability of the middle segment 323, avoid excessive resistance of the middle segment 323, and appropriately reduce the manufacturing process difficulty and manufacturing cost of the middle segment 323.

[0051] Optionally, the width D3 at the narrowest point of the middle segment 323 can be 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm or 0.1mm, or other values ​​within the above range. This embodiment does not limit this value.

[0052] In all the above embodiments, the width of any part of the first edge connection line 32 is within the range of 0.05mm-0.3mm. This can avoid the resistance of the first edge connection line 32 being too high, and can also appropriately reduce the difficulty and cost of the manufacturing process of the first edge connection line 32.

[0053] Optionally, the width of any part on the first edge connecting line 32 can be 0.05mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm or 0.3mm, or other values ​​within the above range. This embodiment does not limit this.

[0054] The structure of the second edge connecting line 33 will be described below with reference to the accompanying drawings.

[0055] like Figure 1 As shown, in the first embodiment, the second edge connecting line 33 has a third sidewall 331 and a fourth sidewall 332. The third sidewall 331 and the fourth sidewall 332 are distributed opposite to each other in the width direction (second direction Y) of the second edge connecting line 33, and the extension direction of the third sidewall 331 is parallel to the extension direction of the fourth sidewall. That is, the width of the second edge connecting line 33 is uniform, thereby ensuring that the resistance of the second edge connecting line 33 is uniform in its extension direction, optimizing the current collection effect of the second edge connecting line 33, and also helping to reduce the manufacturing process difficulty of the second edge connecting line 33.

[0056] like Figure 4 As shown, in the second embodiment, along the first direction X, the width of the second edge connection line 33 gradually decreases in the direction away from the edge pad 31. That is, the end of the second edge connection line 33 closer to the edge pad 31 has a larger width, which is beneficial to improving the connection reliability between the second edge connection line 33 and the edge pad 31. At the same time, it can also reduce the width of the end of the second edge connection line 33 connected to the edge pad 31, thereby reducing the resistance at this end and improving the current transmission capability between the second edge connection line 33 and the edge pad 31. When the width of the second edge connection line 33 gradually decreases in the direction away from the edge pad 31, the amount of raw materials used for the second edge connection line 33 can be saved. At the same time, since the width of the second edge connection line 33 is reduced, the second fine gate 22 located on both sides of the second edge connection line 33 can be appropriately extended, which is beneficial to improving the current collection capability of the second fine gate 22, and thus beneficial to improving the output power of the back contact battery 10.

[0057] In both of the above embodiments, the width of any part of the second edge connection line 33 is D2, and both satisfy the range of 0.03mm-0.25mm. This can avoid the resistance of the second edge connection line 33 being too high, and can also appropriately reduce the difficulty and cost of the fabrication process of the second edge connection line 33.

[0058] Optionally, the width of any part on the second edge connecting line 33 can be 0.03mm, 0.05mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm or 0.25mm, or other values ​​within the above range. This embodiment does not limit this.

[0059] The structure of edge pad 31 is described below with reference to the attached drawings.

[0060] In some embodiments, the area of ​​the edge pad 31 is greater than or equal to 0.5 mm. 2 If the area of ​​edge pad 31 is too small (e.g., less than 0.5mm), 2 This can lead to insufficient contact area between the solder ribbon and the edge pad 31, resulting in decreased reliability of the connection between the edge pad 31 and the solder ribbon. Furthermore, if the area of ​​the edge pad 31 is too small, it becomes difficult to solder the solder ribbon to the edge pad 31, increasing the risk of cold solder joints. On the other hand, when the area of ​​the edge pad 31 is too small, its current carrying capacity decreases, increasing the risk of overheating and affecting its electrical reliability.

[0061] Therefore, when the area of ​​the edge pad 31 meets the above range, it not only helps to improve the connection reliability between the edge pad 31 and the solder strip, but also improves the current carrying capacity of the edge pad 31.

[0062] Optionally, the area of ​​the edge pad 31 can be 0.5 mm. 2 0.6mm 2 0.7mm 2 0.8mm 2 0.9mm 2 1mm 2 1.1mm 2 1.2mm 2 1.3mm 2 1.4mm 2 Or 1.5mm 2 It can also be other values ​​within the above range, and this embodiment does not limit it.

[0063] like Figure 1As shown, in some embodiments, the edge pad group 3 has two edge pads 31, and the distance L1 between the two edge pads 31 along the first direction X satisfies: 3mm ≤ L1 ≤ 4.5mm. If the distance between the two edge pads 31 meets the above range, when the two edge pads 31 are respectively connected to the solder strip, the stress applied by the solder strip to the back contact battery 10 can be better dispersed. Moreover, the distance between the two edge pads 31 is always sufficient, which helps to shorten the length of the first edge connection line 32, thereby reducing the resistance loss of the first edge connection line 32.

[0064] Optionally, the spacing L1 between the two edge pads 31 can be 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm or 4.5mm, or other values ​​within the above range. This embodiment does not limit this.

[0065] In other embodiments, the edge pad group 3 may also have 3, 4 or more edge pads 31, and this application embodiment does not limit this.

[0066] Taking edge pad group 3 with two edge pads 31 as an example, the areas of the two edge pads 31 can be equal or unequal.

[0067] In some embodiments, such as Figure 1 As shown, when the areas of the two edge pads 31 are not equal, the two edge pads 31 are respectively referred to as the first edge pad 311 and the second edge pad 312. Along the first direction X, the first edge pad 311 is located at the end of the edge pad group 3 near the edge of the body 1, and the second edge pad 312 is located at the end of the edge pad group 3 from the edge of the body 1. The area of ​​the first edge pad 311 is smaller than the area of ​​the second edge pad 312.

[0068] In this embodiment, the first edge pad 311 is located near the edge of the body 1. After the solder strip is led out from the first edge pad 311, it needs to be connected to another adjacent back contact battery 10. The first edge pad 311 will bear greater shear force and tensile stress than the second edge pad 312. When the area of ​​the first edge pad 311 is set to be smaller, the stiffness of the first edge pad 311 is lower. When subjected to force, it can absorb some energy through its own deformation, thereby playing a role in buffering stress and helping to reduce the risk of warping or microcracks in the back contact battery 10 due to excessive stress. Moreover, reducing the area of ​​the first edge pad 311 helps to reduce the amount of raw materials used in the first edge pad 311, thereby helping to reduce the manufacturing cost of the back contact battery 10. Increasing the area of ​​the second edge pad 312 helps to improve the mechanical strength of the second edge pad 312 and the connection reliability between the second edge pad 312 and the solder strip. If the first edge pad 311 is subjected to excessive stress, the first edge pad 311 may detach from the solder strip or peel off from the body 1. In this case, the second edge pad 312, which has a larger area and more reliable structure, can maintain the connection with the solder strip and ensure that the current of the back contact battery 10 can be discharged normally.

[0069] In some embodiments, the ratio of the area of ​​the first edge pad 311 to the area of ​​the second edge pad 312 is 1:1.8 to 1:2.5, that is, the area of ​​the second edge pad 312 can be 1.8 to 2.5 times the area of ​​the first edge pad 311. When the ratio of the area of ​​the first edge pad 311 to the area of ​​the second edge pad 312 meets the above range, the area sizes of the first edge pad 311 and the second edge pad 312 are more reasonable, which can not only ensure the structural reliability of the first edge pad 311 and the second edge pad 312, but also reduce the risk of warping or microcracks in the back contact battery 10 due to excessive stress, and also reduce the manufacturing cost of the back contact battery 10.

[0070] In some embodiments, the back contact battery 10 can be a gridless battery, such as... Figure 5As shown, the back surface of the gridless back contact battery 10 is provided with a fine grid 2 and an edge pad group 3. The edge pad group 3 includes a first edge pad group 3A and a second edge pad group 3B. The edge pad 31 of one of the first edge pad group 3A and the second edge pad group 3B is a positive electrode pad, and the edge pad 31 of the other is a negative electrode pad. In this embodiment, taking the edge pad 31 of the first edge pad group 3A as a positive electrode pad and the edge pad 31 of the second edge pad group 3B as a negative electrode pad as an example, the specific structure of the gridless back contact battery 10 is described in detail: the first fine grid 21 connected to the first edge pad group 3A is the first positive electrode fine grid 21', and the second fine grid 22 disposed at intervals from the first edge pad group 3A is the second negative electrode fine grid 22'. The first positive electrode fine grid 21' and the second negative electrode fine grid 22' can be alternately distributed in the first direction X. The first fine gate 21 connected to the second edge pad group 3B is the first negative fine gate 21". The second fine gate 22, spaced apart from the second edge pad group 3B, is the second positive fine gate 22". The first negative fine gate 21" and the second positive fine gate 22" can be alternately distributed in the first direction X. Along the second direction Y, the first positive fine gate 21' and the second positive fine gate 22" are an integral structure, which can also be understood as the first positive fine gate 21' and the second positive fine gate 22" being two adjacent regions on the positive fine gate. Along the second direction Y, the second negative fine gate 22' and the first negative fine gate 21" are an integral structure, which can also be understood as the second negative fine gate 22' and the first negative fine gate 21" being two adjacent regions on the negative fine gate.

[0071] like Figure 1 As shown, in some embodiments, the back contact battery 10 without a main grid also includes an intermediate pad 4, which is disposed on the back surface of the body 1. Along the first direction X, the intermediate pad 4 is disposed on the side of the edge pad group 3 away from the edge of the body 1. The intermediate pad 4 has the same polarity as the first fine grid 21, and the two are electrically connected. That is, the intermediate pad 4 is disposed in the middle region of the body 1 to collect the current on the first fine grid 21 in the middle region. Along the second direction Y, the two sides of the intermediate pad 4 are respectively spaced apart from the second fine grid 22, that is, the second fine grid 22 is disconnected at the intermediate pad 4 to avoid short circuit caused by the second fine grid 22 with opposite polarity being electrically connected to the intermediate pad 4. The intermediate pad 4 is also used to connect with the solder ribbon to transfer the current on the first fine grid 21 in the middle region to the solder ribbon. Figure 5 As shown, the intermediate pad 4 includes a first intermediate pad 41 and a second intermediate pad 42. The first intermediate pad 41 is correspondingly arranged with the first edge pad group 3A along the first direction X. The first intermediate pad 41 and the first edge pad group 3A have the same polarity and are positive pads. The second intermediate pad 42 is correspondingly arranged with the second edge pad group 3B along the first direction X. The second intermediate pad 42 and the second edge pad group 3B have the same polarity and are negative pads.

[0072] When multiple back-contact cells 10 without main grids are used to form a photovoltaic module, two adjacent back-contact cells 10 are electrically connected by solder strips. One end of the solder strip is soldered and electrically connected to the edge pad 31 and the first intermediate pad 41 of the first edge pad group 3A of one of the back-contact cells 10, and the other end is soldered and electrically connected to the edge pad 31 and the second intermediate pad 42 of the second edge pad group 3B of the other back-contact cell 10.

[0073] like Figure 5 As shown, in some embodiments, the back contact battery 10 without a main grid is further provided with edge grid lines 5 at both ends along the second direction Y, and the edge grid lines 5 extend along the first direction X. The polarity of the edge grid lines 5 is opposite to that of the adjacent intermediate pad 4 and the adjacent edge pad group 3, and is used to electrically connect with the fine grid 2 interrupted by the intermediate pad 4 and the fine grid 2 interrupted by the edge pad group 3, so as to collect the current collected by the interrupted fine grid 2, thereby improving the efficiency of the back contact battery 10. The polarity of the two edge grid lines 5 located at both ends of the back contact battery 10 along the second direction Y can be the same or opposite, and this embodiment does not limit this.

[0074] In some embodiments, the back contact battery 10 can be a battery with a main grid, such as... Figure 6 As shown, the back surface of the back contact battery 10 with a main grid is provided with a fine grid 2, an edge pad group 3, and a main grid 6. The main grid 6 extends along a first direction X. The first fine grid 21, the edge pad group 3, and the main grid 6 have the same polarity. The two ends of the main grid 6 along the first direction X are electrically connected to the edge pads 31 of the edge pad group 3, respectively. The first fine grid 21 intersects with and is electrically connected to the main grid 6, so that the main grid 6 can collect and output the photocurrent collected by the first fine grid 21. The second fine grid 22 is spaced apart from the main grid 6, that is, the second fine grid 22 is disconnected at the main grid 6 to avoid short circuit due to electrical connection between the second fine grid 22 and the main grid 6.

[0075] Combination Figure 7As shown, the main gate 6 includes a first main gate 61 and a second main gate 62, one of which is the positive main gate and the other is the negative main gate. The edge pad group 3 includes a first edge pad group 3A and a second edge pad group 3B, one of which has an edge pad 31 that is a positive pad and the other has an edge pad 31 that is a negative pad. This embodiment takes a first main grid 61 as the positive main grid, a second main grid 62 as the negative main grid, and edge pads 31 of the first edge pad group 3A as positive pads and edge pads 31 of the second edge pad group 3B as negative pads as examples to describe the specific structure of the back contact battery 10 with main grids: The first fine grid 21 connected to the first edge pad group 3A is the first positive fine grid 21', and the second fine grid 22 spaced apart from the first edge pad group 3A is the second negative fine grid 22'. The first positive fine grid 21' and the second negative fine grid 22' can be alternately distributed in the first direction X. The first positive fine grid 21' is connected to the first main grid 61, and the second negative fine grid 22' is spaced apart from the first main grid 61. The first fine gate 21 connected to the second edge pad group 3B is the first negative gate 21". The second fine gate 22, spaced apart from the second edge pad group 3B, is the second positive gate 22". The first negative gate 21" and the second positive gate 22" can be alternately distributed in the first direction X. The first negative gate 21" is connected to the second main gate 62, and the second positive gate 22" is spaced apart from the second main gate 62. Along the second direction Y, the first positive gate 21' and the second positive gate 22" are an integral structure, which can also be understood as the first positive gate 21' and the second positive gate 22" being two adjacent regions on the positive gate. Along the second direction Y, the second negative gate 22' and the first negative gate 21" are an integral structure, which can also be understood as the second negative gate 22' and the first negative gate 21" being two adjacent regions on the negative gate.

[0076] When multiple back-contact cells 10 with main grids are used to form a photovoltaic module, adjacent back-contact cells 10 are electrically connected by solder strips. One end of the solder strip is soldered and electrically connected to the edge pad 31 of the first edge pad group 3A and the first main grid 61 of one of the back-contact cells 10, and the other end is soldered and electrically connected to the edge pad 31 of the second edge pad group 3B and the second main grid 62 of the other back-contact cell 10. The first main grid 61 and the second main grid 62 may be provided with grid pads for soldering with the solder strips. This application embodiment does not limit the specific structure of the first main grid 61 and the second main grid 62.

[0077] like Figure 7As shown, the back contact battery 10 with a main grid is further provided with edge grid lines 5 at both ends along the second direction Y, and the edge grid lines 5 extend along the first direction X. The polarity of the edge grid lines 5 is opposite to that of the adjacent main grid 6 and the adjacent edge pad group 3, and is used to electrically connect with the fine grid 2 interrupted by the main grid 6 and the fine grid 2 interrupted by the edge pad group 3, so as to collect the current collected by the interrupted fine grid 2, thereby improving the efficiency of the back contact battery 10. The polarities of the two edge grid lines 5 located at both ends of the back contact battery 10 along the second direction Y can be the same or opposite, and this embodiment does not limit this.

[0078] In some embodiments, the back contact cell 10 can be one of the following: interdigitated back contact (IBC), heterojunction back contact (HBC), or tunnel oxide back contact (TBC). For an IBC cell, along its thickness direction, the IBC cell sequentially includes a silicon nitride inversion layer, an N+ front surface field, an N-type substrate silicon layer, a P+ emitter, an N+ back field, an aluminum oxide passivation layer, a silicon nitride antireflection layer, and a silver electrode. IBC cells utilize ion implantation technology to obtain P- and N-regions with good uniformity and precise controllable junction depth. The absence of grid lines on the front of the cell eliminates light-blocking current loss from metal electrodes, maximizing the utilization of incident photons and improving short-circuit current by approximately 7% compared to conventional solar cells. Due to the back-contact structure, grid line shading is not a concern, allowing for a wider grid line ratio, thus reducing series resistance and achieving a high fill factor. Optimized design of surface passivation and light-trapping structures can be achieved, resulting in lower front-surface recombination rates and surface reflections.

[0079] HBC cells effectively combine the advantages of IBC and heterojunction cells. Their front surface passivation layer uses hydrogenated amorphous silicon, while N-type and P-type amorphous silicon films are deposited on the back side to form a heterojunction. HBC cells fully utilize the superior surface passivation properties of amorphous silicon, and the heterojunction structure formed on the back side exhibits excellent passivation, enabling the simultaneous achievement of higher short-circuit current and open-circuit voltage, thereby improving photoelectric conversion efficiency.

[0080] For TBC cells, the advantages of both Topcon's tunneling oxide layer technology and IBC back-side electrode arrangement are combined, resulting in significantly improved passivation and open-circuit voltage, achieving higher cell conversion efficiency while maintaining economic viability. The complete TBC cell production process mainly includes depositing the tunneling oxide layer and P+ polycrystalline silicon, depositing the passivation film, and printing electrodes on the back of the silicon wafer. Building upon the TOPCon production process, TBC cells require additional back-side electrode processes such as masking, laser grooving, PN region fabrication, and etching. Masking is primarily performed using APCVD or PECVD, PN region fabrication is mainly done using PECVD, etching primarily employs traditional wet processing equipment, and grooving is performed using laser equipment.

[0081] This application also provides a back-contact stacked battery 20, such as Figure 8 As shown, the back-contact tandem solar cell 20 includes a back-contact bottom cell 201 and a perovskite top cell 202, with the perovskite top cell 202 electrically connected to the light-facing surface of the back-contact bottom cell 201. The back-contact bottom cell 201 can be either a back-contact cell 10 with a main grid or a back-contact cell 10 without a main grid, as described above. The perovskite top cell 202 is a thin-film solar cell with perovskite material as the photoactive layer. The structure of the perovskite top cell 202 mainly consists of the following key components: a transparent conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode. These components work together to enable the perovskite top cell 202 to effectively absorb sunlight and convert it into electrical energy. The perovskite material in the perovskite light-absorbing layer has excellent light absorption performance, absorbing a wider spectral range and effectively converting short-wavelength spectra, giving the perovskite top cell 202 high photoelectric conversion efficiency.

[0082] This application also provides a photovoltaic module, such as... Figure 9 and Figure 10 As shown, the photovoltaic module includes multiple photovoltaic cells and solder ribbons 30. The photovoltaic cells are either the back-contact cells 10 described above, or the back-contact tandem cells 20 described above. The main grids 6 of two adjacent photovoltaic cells along the first direction X are connected by solder ribbons 30.

[0083] The photovoltaic module also includes a front panel 40, a front encapsulation layer 50, a back encapsulation layer 60, and a back sheet 70. The front panel 40 and the back sheet 70 together sandwich the front encapsulation layer 50, the back contact cell 10, the solder ribbon 30, and the back encapsulation layer 60, and form a photovoltaic module through lamination. The front encapsulation layer 50 protects the light-facing side of the back contact cell 10, and the back encapsulation layer 60 protects the back-facing side of the back contact cell 10. During the lamination process of the photovoltaic module, the front encapsulation layer 50 and the back encapsulation layer 60 encapsulate and protect the back contact cell 10 and the solder ribbon 30, preventing external environmental factors from affecting their performance. They also bond the front panel 40, the back sheet 70, the back contact cell 10, and the solder ribbon 30 into a single unit.

[0084] The front panel 40 and back panel 70 can be made of rigid materials such as tempered glass, polyethylene terephthalate (PET), and polycarbonate (PC), or flexible materials such as polyvinyl fluoride (PVF), ethylene-tetrafluoroethylene copolymer (ETFE), and polyvinylidene fluoride (PVDF). The front encapsulation layer 50 and the back encapsulation layer 60 are adhesive films, which can be made of materials such as ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), and polyvinyl butyral (PVB). The front encapsulation layer 50 and the back encapsulation layer 60 can also be EPE film (EVA-POE-EVA co-extrusion structure) or EP film (EVA-POE co-extrusion structure).

[0085] The above description is merely a preferred embodiment of this application and is not intended to limit the application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application. Alternatively, the scope of this application is defined by the appended claims.

Claims

1. A back-contact battery, characterized in that, Includes a body, the back surface of which is provided with a fine grid and an edge pad group; The fine grid includes a first fine grid and a second fine grid; Along a first direction, at least one end of the body is provided with the edge pad group, the edge pad group being electrically connected to the first fine gate and spaced apart from the second fine gate; The edge pad group has at least two edge pads spaced apart along the first direction, and adjacent edge pads are electrically connected by a first edge connection line.

2. The back contact battery according to claim 1, characterized in that, The edge pad group further includes a second edge connection line. Along the first direction, the second edge connection line is disposed at one end of the edge pad group near the edge of the body, and the second edge connection line is electrically connected to the edge pad. The width D1 of the first edge connection line is greater than the width D2 of the second edge connection line.

3. The back contact battery according to claim 2, characterized in that, The widths D1 and D2 of the first edge connecting line and the second edge connecting line satisfy the following: 1.2:1 ≤ D1:D2 ≤ 2:

1.

4. The back contact battery according to claim 1, characterized in that, The first edge connecting line has a first sidewall and a second sidewall, the first sidewall and the second sidewall being distributed opposite to each other in the width direction of the first edge connecting line; The extension direction of the first sidewall is parallel to the extension direction of the second sidewall.

5. The back contact battery according to claim 1, characterized in that, The first edge connecting line includes a middle segment and an edge segment, and the edge segment is provided at both ends of the middle segment along the first direction; The maximum width of the middle segment is less than or equal to the minimum width of the edge segment.

6. The back contact battery according to claim 5, characterized in that, The minimum width on the middle segment is D3, and the maximum width on the edge segment is D4. D3 and D4 satisfy: 1:6≤D3:D4≤1:

3.

7. The back contact battery according to claim 1, characterized in that, The area of ​​the edge pad is greater than or equal to 0.5 mm. 2 .

8. The back contact battery according to claim 1, characterized in that, The edge pad group has two edge pads, and the distance L1 between the two edge pads along the first direction satisfies: 3mm≤L1≤4.5mm.

9. The back contact battery according to claim 1, characterized in that, The edge pads include a first edge pad and a second edge pad. Along the first direction, the first edge pad is located at one end of the edge pad group near the edge of the body, and the second edge pad is located at one end of the edge pad group away from the edge of the body. The area of ​​the first edge pad is smaller than the area of ​​the second edge pad.

10. The back contact battery according to claim 9, characterized in that, The ratio of the area of ​​the first edge pad to the area of ​​the second edge pad is 1:1.8 to 1:2.

5.

11. A back-contact stacked battery, characterized in that, It includes a back-contact bottom cell and a perovskite top cell, wherein the perovskite top cell is electrically connected to the light-facing surface of the back-contact bottom cell, and the back-contact bottom cell is the back-contact cell according to any one of claims 1-10.

12. A photovoltaic module, characterized in that, include: Multiple photovoltaic cells, wherein the photovoltaic cells are back-contact cells as described in any one of claims 1-10, or the photovoltaic cells are back-contact stacked cells as described in claim 11; The welding strip connects two adjacent photovoltaic cells along the first direction electrically.

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