Back-contact solar cell and photovoltaic module

Abstract

Disposed in the present application are a back-contact solar cell and a photovoltaic module. The back-contact solar cell comprises: a cell body comprising a first surface and a second surface arranged opposite each other; a plurality of first fine fingers and a plurality of second fine fingers disposed on the first surface, wherein the first fine fingers and the second fine fingers extend in a first direction and are alternately spaced in a second direction, the first direction intersecting the second direction; and a plurality of first insulating blocks arranged at intervals in the second direction and respectively covering the second fine fingers, wherein in the second direction, a distance between edges of adjacent first insulating blocks is D1, and D1 ≥ 80 μm. The distance between two adjacent first insulating blocks in the second direction is sufficiently large to reserve a safe distance for paste flow, thereby preventing paste used to form the first insulating blocks from flowing to cover the first fine fingers, ensuring the stability of electrical connection between the first fine fingers and a first conductive member, and thus improving the stability of performance of the back-contact solar cell.

Description

Back contact batteries and photovoltaic modules Technical Field

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

[0002] Solar cells are the core component of photovoltaic modules, converting solar energy into electrical energy. Back-contact solar cells have both the positive and negative grid lines located on the back of the cell to prevent them from obstructing the front, thus improving the photoelectric conversion efficiency.

[0003] In the prior art, when using solder strips or connecting the main grid and the fine grid, an insulating block needs to be placed between the solder strips or the main grid and the fine grid with opposite polarities. However, the insulating block often flows to cover the fine grid with the same polarity during the printing process, causing the electrical connection between the solder strips or the main grid and the fine grid with the same polarity to fail, affecting the performance of the back contact battery. Summary of the Invention

[0004] The purpose of this application is to provide a back contact battery and photovoltaic module to avoid the failure of electrical connection between conductive parts and fine grids of the same polarity caused by the flow of insulating blocks during the printing process, thereby improving the stability of the back contact battery performance.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] A back-contact battery, comprising:

[0007] The battery body includes a first surface and a second surface that are disposed opposite to each other;

[0008] A plurality of first fine grids and a plurality of second fine grids are disposed on a first surface; the first fine grids and the second fine grids extend along a first direction and are alternately spaced along a second direction; the first direction and the second direction intersect.

[0009] Multiple first insulating blocks are arranged at intervals along a second direction and respectively cover multiple second fine grids; along the second direction, the distance between the edges of adjacent first insulating blocks is D1, where D1≥80μm.

[0010] During the printing process of the first insulating block, the paste may flow to cover the first fine grid, causing the electrical connection between the first conductive element and the first fine grid to fail. In view of this, along the second direction, the distance between the edges of adjacent first insulating blocks is D1, where D1 ≥ 80 μm. This technical solution ensures a sufficiently large distance between two adjacent first insulating blocks along the second direction, thus providing a safe distance for paste flow and preventing the paste forming the first insulating block from flowing to cover the first fine grid. This guarantees the stability of the electrical connection between the first fine grid and the first conductive element, thereby improving the stability of the back contact battery performance.

[0011] In one implementation, the thickness of the first insulating block is h1 along the thickness direction of the battery body, where 20μm≤h1≤100μm. This ensures good isolation between the second fine grid and the first conductive element, while also preventing the slurry forming the first insulating block from climbing up and covering the first fine grid, thus ensuring the reliability of the electrical connection between the first fine grid and the first conductive element, and avoiding waste of the raw materials of the first insulating block.

[0012] In one implementation, along the thickness direction of the battery body, the thickness of the first insulating block is h1, and the thickness of the first fine grid is h2, where h1 / h2≤4. This configuration ensures that the side surface of the first fine grid can block the slurry forming the first insulating block, preventing the slurry from rising to cover the upper surface of the first fine grid, thus further ensuring the reliability of the electrical connection between the first fine grid and the first conductive element.

[0013] In one implementation, the back contact battery further includes a first conductive element that extends along a second direction and is electrically connected to a first fine grid, so as to collect the current collected by the multiple first fine grids through the first conductive element and transmit the collected current to an external circuit.

[0014] In one implementation, the intersection of the first conductive element and the first fine grid has a side protrusion extending along a first direction. This configuration increases the contact area between the first conductive element and the first fine grid, thereby reducing the transmission resistance between them, decreasing current loss, and improving the photoelectric conversion efficiency of the back contact battery.

[0015] In one implementation, a recess is formed at the intersection of the top of the side protrusion and the first fine gate. Specifically, along the first direction, the width of the intersection of the side protrusion and the first fine gate is appropriately reduced, thereby saving more raw materials for the first conductive element while ensuring a reduction in transmission resistance.

[0016] In one implementation, the back contact battery further includes a plurality of second insulating blocks, which are spaced apart along a second direction and respectively cover a plurality of first fine grids. Along the second direction, the distance between the edges of adjacent second insulating blocks is D2, where D2 ≥ 80 μm and / or D2 ≥ D1. This technical solution ensures a sufficiently large distance between two adjacent second insulating blocks along the second direction, thus providing a safe distance for slurry flow. This prevents the slurry forming the second insulating blocks from flowing into and covering the second fine grids, ensuring the stability of the electrical connection between the second fine grids and the second conductive element, thereby improving the stability of the back contact battery performance.

[0017] In one implementation, the back contact battery further includes a plurality of second insulating blocks, which are spaced apart along a second direction and respectively cover a plurality of first fine grids. Along the second direction, the width of each second insulating block is S1, and the width of each first insulating block is S2, wherein S2 is greater than S1; and / or, S2 is 50μm-250μm larger than S1. This arrangement reduces the amount of insulating material (e.g., insulating adhesive) used in the second insulating blocks while ensuring sufficient insulation between the first and second current collection layers.

[0018] In one implementation, the first surface has a first region and a second region alternately arranged along a second direction, the first region and the second region extending along the first direction. A first fine gate is disposed in the first region, and a second fine gate is disposed in the second region. The second region has a groove structure, which is recessed relative to the first region towards the second surface. This prevents the second fine gate in the groove structure from being covered by the second insulating block (or by the diffusion band), thus avoiding poor contact.

[0019] In one implementation, along the second direction, the distance between the edges of adjacent second insulating blocks is D2, where D2 > D1, and / or D2 ≥ 120 μm. This technical solution ensures a sufficiently large distance between two adjacent second insulating blocks along the second direction, thus providing a safe distance for slurry flow. This prevents the slurry forming the second insulating blocks from flowing into and covering the second fine grid, ensuring the stability of the electrical connection between the second fine grid and the second conductive element, thereby improving the stability of the back contact battery performance.

[0020] In one implementation, the back contact battery further includes a second conductive element that extends along a second direction and is electrically connected to a second grid, so as to collect the current collected by the multiple second grids through the second conductive element and transmit the collected current to an external circuit.

[0021] In one implementation, the battery body includes: a semiconductor substrate, a first current collecting layer, and a second current collecting layer, the first and second current collecting layers extending along a first direction and alternately spaced along a second direction; a first fine grid is disposed on the first current collecting layer, and a second fine grid is disposed on the second current collecting layer, with the first and second current collecting layers collecting current of opposite types; an isolation region extending along the first direction is provided between adjacent first and second current collecting layers; along the second direction, the isolation region between adjacent first and second current collecting layers is at least partially covered by a first insulating block. This avoids the bonding material overflowing into the isolation region and connecting to the second fine grid 4 during the welding process between the first fine grid and the first conductive element, thus preventing a short circuit and improving the reliability of the back contact battery.

[0022] In one implementation, along the second direction, the width of the first insulating block extending onto the adjacent first current collecting layer is L1, where L1 ≥ 40 μm. This technical solution ensures that after the first insulating block is cured, it does not affect the reliability of the electrical connection between the first fine grid and the first conductive element, thus avoiding poor soldering. Furthermore, extending the first insulating block onto the adjacent first current collecting layer also prevents the paste forming the first conductive element from overflowing into the isolation area or the second current collecting layer and connecting with the second fine grid, which could lead to a short circuit in the battery cell, thereby contributing to improved battery string reliability.

[0023] In one implementation, the first current collecting layer and the second current collecting layer are transparent conductive layers; or, the first current collecting layer and the second current collecting layer are doped semiconductor layers, and the doping types of the two are opposite.

[0024] In one implementation, diffusion bands are formed on both sides of the first insulating block along a second direction. The diffusion bands include at least one material from the slurry used to form the first insulating block. Along the second direction, the diffusion bands extend from the edge of the first insulating block to the edge of the adjacent first fine grid. During the fabrication of the first insulating block, after slurry printing or laser transfer and before the slurry cures, one or more organic substances in the slurry diffuse to both sides of the first insulating block, forming diffusion bands on both sides. The diffusion of organic substances from the slurry forming the first insulating block to both sides can improve the adhesion between the first insulating block and the first surface, preventing the first insulating block from detaching.

[0025] In one implementation, the thickness of the diffusion band is less than the thickness of the first fine gate along the thickness direction of the semiconductor substrate. Using this technique, the thickness of the first fine gate prevents the paste from continuing to extend and flow, further ensuring the stability of the electrical connection between the first fine gate and the first conductive element.

[0026] In one implementation, the first fine grid includes first thickened segments spaced apart along a first direction, and along a second direction, the width of the first thickened segments is greater than the width of the rest of the first fine grid excluding the first thickened segments. By adopting this technical solution, the setting of the first thickened segments can increase the contact area between the first fine grid and the first conductive element, thereby reducing the transmission resistance between the first conductive element and the first fine grid, reducing current loss, and improving the photoelectric conversion efficiency of the back contact battery.

[0027] And / or, the second fine grid includes second thickened segments spaced apart along a first direction, and along a second direction, the width of the second thickened segments is greater than the width of the remaining portion of the second fine grid excluding the second thickened segments. By employing this technical solution, the arrangement of the second thickened segments can increase the contact area between the second fine grid and the second conductive element, thereby reducing the transmission resistance between the second conductive element and the second fine grid, reducing current loss, and improving the photoelectric conversion efficiency of the back contact battery.

[0028] In one implementation, along the second direction, the distance between the edge of the second thickened section and the adjacent second insulating block is D3, where D3 ≥ 50 μm. This setting provides a safe distance for slurry flow, preventing the slurry forming the second insulating block from flowing to cover the second thickened section, ensuring the stability of the electrical connection between the second thickened section and the second conductive element, and thus improving the stability of the back contact battery performance.

[0029] And / or, along the second direction, the distance between the edge of the first thickened section and the adjacent first insulating block is D4, where D4 ≥ 50 μm. This setting provides a safe distance for slurry flow, preventing the slurry forming the first insulating block from flowing into and covering the first thickened section, ensuring the stability of the electrical connection between the first thickened section and the first conductive element, thereby improving the stability of the back contact battery performance.

[0030] In one implementation, the first conductive element is the main grid; and the organic matter in the slurry forming the main grid is mutually soluble with the organic matter in the slurry forming the first insulating block. Using this technical solution, after the organic matter in the slurry of the main grid and the organic matter in the slurry of the first insulating block are mutually soluble, the adhesion between the first conductive element and the first insulating block is strengthened, further preventing the first conductive element from detaching.

[0031] A photovoltaic module includes a back contact cell as described in any of the above; the back contact cell further includes a first conductive element extending along a second direction and being directly physically and electrically connected to a first grid, or electrically connected to the first grid through a bonding layer.

[0032] Compared with the prior art, the beneficial effects of the photovoltaic module provided in this application are the same as those of the back contact battery described above, and will not be repeated here. Attached Figure Description

[0033] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0034] Figure 1 is an overall schematic diagram of the back contact battery provided in an embodiment of this application;

[0035] Figure 2 is a magnified view of region B in Figure 1;

[0036] Figure 3 is a magnified view of region A in Figure 1;

[0037] Figure 4 is a partial cross-sectional view along CC in Figure 1;

[0038] Figure 5 is a partial cross-sectional view along DD in Figure 1;

[0039] Figure 6 is a schematic diagram of the diffusion bands formed on both sides of the first insulating block provided in the embodiment of this application;

[0040] Figure 7 is a cross-sectional view of the diffusion bands formed on both sides of the first insulating block provided in an embodiment of this application;

[0041] Figure 8 is a schematic diagram of the formation of the second conductive element provided in an embodiment of this application;

[0042] Figure 9 is a partial cross-sectional view of the formation of the second conductive element provided in an embodiment of this application;

[0043] Figure 10 is a schematic diagram of the partial thickening of the first fine grid provided in an embodiment of this application;

[0044] Figure 11 is a schematic diagram of the second fine gate partially thickened according to an embodiment of this application.

[0045] Reference numerals: 1-First conductive element, 2-Isolation area, 3-First insulating block, 4-Second fine grid, 41-Second thickened section, 5-Second current collecting layer, 6-First fine grid, 61-First thickened section, 7-First current collecting layer, 8-Second conductive element, 81-Side protrusion, 9-Second insulating block, 10-Diffusion band. Detailed Implementation

[0046] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0047] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise expressly specified. "Several" means one or more, unless otherwise expressly specified.

[0049] In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0050] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0051] Referring to Figures 1 and 2, the back-contact battery provided in this embodiment includes a battery body, a first fine grid 6, a second fine grid 4, and a plurality of first insulating blocks 3. The battery body includes a first surface and a second surface opposite each other, that is, two surfaces opposite each other along the thickness direction of the battery body are the first surface and the second surface, respectively. In this embodiment, the first surface corresponds to the back surface of the back-contact battery, also referred to as the back side; the second surface corresponds to the light-facing surface of the back-contact battery, also referred to as the front side.

[0052] A plurality of first fine grids 6 and a plurality of second fine grids 4 are disposed on a first surface; the first fine grids 6 and the second fine grids 4 extend along a first direction, and the plurality of first fine grids 6 and the plurality of second fine grids 4 are alternately spaced along a second direction. In some embodiments, the first surface has a first region, a second region, and an isolation region 2, wherein the first region and the second region are alternately spaced along the second direction, and an isolation region 2 is provided between the first region and the second region. The first region and the second region extend along the first direction, that is, the length of the first region and the second region extends along the first direction. The first direction and the second direction intersect, that is, the first direction is different from the second direction, and the angle between the first direction and the second direction can be an acute angle or a right angle. The first direction can be the length direction of the battery body or the width direction of the battery body. When the first direction is the length direction of the battery body, the second direction is the width direction of the battery body; when the first direction is the width direction of the battery body, the second direction is the length direction of the battery body. The first fine grids 6 are disposed in the first region and extend along the first direction, and the second fine grids 4 are disposed in the second region and extend along the first direction.

[0053] Furthermore, multiple first insulating blocks 3 are spaced apart along the second direction and respectively cover multiple second fine grids 4. During the printing process of forming the first insulating blocks 3, the paste may flow to cover the first fine grids 6, causing the electrical connection between the first fine grids 6 and other components (such as the first conductive element 1) to fail. In view of the above, as shown in FIG2, the distance between the edges of adjacent first insulating blocks 3 along the second direction is D1, where D1 ≥ 80 μm. With this technical solution, the distance between two adjacent first insulating blocks 3 along the second direction is large enough, thus reserving a safe distance for paste flow, thereby preventing the paste forming the first insulating blocks 3 from flowing to cover the first fine grids 6, ensuring the stability of the electrical connection between the first fine grids 6 and other components, and thus improving the stability of the back contact battery performance.

[0054] For example, D1 can be 80μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm, 155μm, 160μm or 165μm, etc.

[0055] In theory, the greater the distance between two adjacent first insulating blocks 3 along the second direction, the better. However, since the width of the current collection layer cannot be too wide, the maximum distance between two adjacent first insulating blocks 3 along the second direction cannot exceed 1000μm.

[0056] In some embodiments, the battery body includes a semiconductor substrate, a first current collecting layer 7, and a second current collecting layer 5. The semiconductor substrate has two opposing surfaces along its thickness direction corresponding to a first surface and a second surface, respectively. The first current collecting layer 7 and the second current collecting layer 5 extend along a first direction and are alternately spaced along a second direction. The first current collecting layer 7 is formed at least in a first region; specifically, it may be formed only in the first region, or it may be formed in both the first region and the isolation region 2. The second current collecting layer 5 is formed at least in a second region; specifically, it may be formed only in the second region, or it may be formed in both the second region and the isolation region 2. When both the first current collecting layer 7 and the isolation region 2 are formed, the first and second current collecting layers 7 and 5 overlap in the isolation region 2. The first and second current collecting layers 7 collect opposite types of current to collect and export electrons and holes, respectively, facilitating the formation of photocurrent.

[0057] A first fine gate 6 is disposed on the first current collecting layer 7 and extends along a first direction, meaning the first fine gate 6 is electrically connected to the first current collecting layer 7 to conduct the charge carriers collected by the first current collecting layer 7. A second fine gate 4 is disposed on the second current collecting layer 5 and extends along the first direction, meaning the second fine gate 4 is electrically connected to the second current collecting layer 5 to conduct the charge carriers collected by the second current collecting layer 5. An isolation region 2 extending along the first direction is provided between adjacent first current collecting layers 7 and second current collecting layers 5 to prevent leakage. In this technical solution, along the second direction, the isolation region 2 between adjacent first current collecting layers 7 and second current collecting layers 5 is at least partially covered by a first insulating block. This prevents bonding material from overflowing into the isolation region and connecting to the second fine gate 4 during the welding process between the first fine gate 6 and the first conductive element 1, thus avoiding short circuits and improving the reliability of the back contact battery.

[0058] In other embodiments, the back contact battery further includes a first conductive element 1, which extends along a second direction and is electrically connected to multiple first fine grids 6. The first conductive element 1 collects the current gathered by the multiple first fine grids 6 and transmits the collected current to an external circuit. A first insulating block 3 is disposed at the intersection of the first conductive element 1 and the second fine grid 4 to block the second fine grid 4 from the first conductive element 1, preventing a short circuit between the two and thus affecting the photoelectric conversion efficiency of the battery cell. As shown in Figure 2, the distance between the edges of adjacent first insulating blocks 3 along the second direction is D1, where D1 ≥ 80 μm. This technical solution ensures a sufficiently large distance between two adjacent first insulating blocks 3 along the second direction, thus providing a safe distance for slurry flow. This prevents the slurry forming the first insulating block 3 from flowing into and covering the first fine grids 6, ensuring the stability of the electrical connection between the first fine grids 6 and the first conductive element 1, thereby improving the stability of the back contact battery performance.

[0059] During the printing process of the first conductive element 1, the paste (e.g., copper) forming the first conductive element 1 can easily flow through the isolation region 2 to the second current collecting layer 5, causing leakage. In view of the above, in some embodiments, as shown in FIG2, the first insulating block 3 extends along the second direction onto the adjacent first current collecting layer 7. Specifically, along the second direction, the first insulating block 3 covers the second current collecting layer 5, the isolation region 2, and a portion of the first current collecting layer 7. This technical solution ensures that after the first insulating block 3 cures, it will not affect the reliability of the electrical connection between the first fine grid 6 and the first conductive element 1, thus avoiding poor soldering. Furthermore, the extension of the first insulating block 3 onto the adjacent first current collecting layer 7 also prevents the paste forming the first conductive element 1 from overflowing into the isolation region 2 or the second current collecting layer 5 and connecting with the second fine grid 4, causing a short circuit in the battery cell, thereby helping to improve the reliability of the battery string.

[0060] Furthermore, along the second direction, the width of the first insulating block 3 extending onto the adjacent first current collecting layer 7 is L1, where L1 ≥ 40 μm. This configuration ensures that the paste forming the first conductive element 1 cannot enter the isolation region 2, further improving the isolation effect of the first insulating block 3. For example, L1 can be 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm, or 50 μm, etc.

[0061] Considering that if the thickness of the first insulating block 3 is too small, a good isolation effect cannot be guaranteed; if the thickness of the first insulating block 3 is too large, a large amount of slurry is required during the formation of the first insulating block 3, and the slurry can easily rise and cover the first fine grid 6, causing the electrical connection between the first fine grid 6 and the first conductive element 1 to fail. In view of the above two situations, in some embodiments, the thickness of the first insulating block 3 is h1 along the thickness direction of the battery body, 20μm≤h1≤100μm. This can ensure a good isolation effect between the second fine grid 4 and the first conductive element 1, and can also prevent the slurry forming the first insulating block 3 from rising and covering the first fine grid 6, thereby ensuring the reliability of the electrical connection between the first fine grid 6 and the first conductive element 1, while also avoiding the waste of raw materials for the first insulating block 3.

[0062] For example, the thickness h1 of the first insulating block 3 can be 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm or 100μm, etc.

[0063] It is understood that the higher the height of the first fine grid 6 along the thickness direction of the battery body, the less likely the slurry forming the first insulating block 3 will climb to the upper surface of the first fine grid 6. In other words, when the height of the first fine grid 6 is high, it acts like a dam, with its sides blocking the flow of the slurry forming the first insulating block 3 and preventing it from climbing to cover the upper surface of the first fine grid 6. In view of the above, in some embodiments, the thickness of the first insulating block 3 is h1, and the thickness of the first fine grid 6 is h2, with h1 / h2 ≤ 4, along the thickness direction of the battery body. This configuration ensures that the sides of the first fine grid 6 can block the slurry forming the first insulating block 3, preventing it from climbing to cover the upper surface of the first fine grid 6, further ensuring the reliability of the electrical connection between the first fine grid 6 and the first conductive element 1.

[0064] For example, h1 / h2 can be 4, 3.5, 3, 2.5, 2, 1.5, 1, or 0.5, etc. Furthermore, along the thickness direction of the battery body, the thickness h2 of the first fine grid 6 can be 5μm, 8μm, 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 25μm, 28μm, or 30μm, etc.

[0065] In other embodiments, the back contact battery further includes a plurality of second insulating blocks 9, spaced apart along a second direction, and each covering a plurality of first fine grids 6. During the printing process of forming the second insulating blocks 9, the paste may flow to cover the second fine grids 4, causing the electrical connection between the second fine grids 4 and other components (such as the second conductive element 8) to fail. In view of the above, as shown in FIG3, along the second direction, the distance between the edges of adjacent second insulating blocks 9 is D2, D2≥80μm and / or D2≥D1. With this technical solution, the distance between two adjacent second insulating blocks 9 along the second direction is large enough, thus reserving a safe distance for paste flow, thereby preventing the paste forming the second insulating blocks 9 from flowing to cover the second fine grids 4, ensuring the stability of the electrical connection between the second fine grids 4 and the second conductive element 8, and thus improving the stability of the back contact battery performance.

[0066] For example, D2 can be 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm, 155μm, 160μm or 165μm, etc.

[0067] The first insulating block 3 and / or the second insulating block 9 can be any shape, such as circular, rectangular, or elliptical.

[0068] In some embodiments, the back contact battery further includes a second conductive element 8, which extends along a second direction and is electrically connected to multiple second fine grids 4. The second conductive element 8 collects the current gathered by the multiple second fine grids 4 and transmits the collected current to an external circuit. A second insulating block 9, corresponding one-to-one with the first fine grid 6, is provided at the intersection of the second conductive element 8 and the first fine grid 6. The second insulating block 9 isolates the first fine grid 6 from the second conductive element 8, preventing a short circuit between the first fine grid 6 and the second conductive element 8, which would affect the photoelectric conversion efficiency of the battery cell.

[0069] In one embodiment, as shown in FIG2, the width of the first insulating block 3 along the second direction is S2, 300μm≤S2≤800μm, to prevent the width of the first insulating block 3 from being too small, thus failing to completely isolate the second fine gate 4 and the first conductive element 1, while also preventing the width of the first insulating block 3 from being too large, thus wasting raw materials. Exemplarily, S2 can be 300μm, 350μm, 400μm, 450μm, 500μm, 550μm, 600μm, 650μm, 700μm, 750μm, or 800μm, etc. Furthermore, along the second direction, the width of the second current collecting layer 5 is W1, 200μm≤W1≤650μm, for example, W1 can be 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, 550μm, 600μm, or 650μm, etc.

[0070] Furthermore, along the second direction, the width of the isolation region 2 is W3, 40μm≤W3≤100μm, to prevent leakage caused by an excessively small width of the isolation region 2, while also preventing the width of the isolation region 2 from affecting the carrier collection efficiency. For example, W3 can be 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, or 100μm, etc.

[0071] In one embodiment, as shown in FIG3, the width of the second insulating block 9 along the second direction is S1, 200μm≤S1≤650μm, to prevent the width of the second insulating block 9 from being too small, thus failing to completely isolate the first fine gate 6 and the second conductive element 8, while also preventing the width of the second insulating block 9 from being too large, thus wasting raw materials. Exemplarily, S1 can be 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, 550μm, 600μm, or 650μm. Furthermore, along the second direction, the width of the first current collecting layer 7 is W2, 200μm≤W2≤600μm, for example, W2 can be 200μm, 220μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, 550μm, or 600μm, etc.

[0072] In some embodiments, along the second direction, the width S2 of the first insulating block 3 is greater than the width S1 of the second insulating block 9, wherein the difference between S2 and S1 is 50μm-250μm, and the difference can be 50μm, 100μm, 150μm, 200μm, or 250μm, etc. This configuration allows for a smaller amount of insulating material (e.g., insulating adhesive) in the second insulating block 9, while ensuring that the first current collecting layer 7 and the second current collecting layer 5 are sufficiently insulated.

[0073] As shown in Figures 4 and 5, in some embodiments, the second region has a groove structure that is recessed relative to the first region towards the second surface, i.e., the groove structure is lower than the rest of the first surface. The second current collecting layer 5 is located within the groove structure; specifically, the second current collecting layer 5 is located at the bottom of the groove structure, and the first current collecting layer 7 is located on the first surface excluding the groove structure. This arrangement allows the presence of the groove structure to at least partially offset the electrode structures electrically connected to the first current collecting layer 7 and the second current collecting layer 5 along the thickness direction of the battery body, thus helping to suppress leakage current.

[0074] When the second region has a groove structure, as shown in Figure 4, during the formation of the second insulating block 9, the slurry forming the second insulating block 9 flows more easily into the groove structure along the M direction under the action of gravity, making it easier for the slurry forming the second insulating block 9 to cover the second fine grid 4. In view of the above, in this technical solution, along the second direction, the distance between the edges of adjacent second insulating blocks 9 is D2, where D2 > D1, or D2 ≥ 120 μm. This setting further increases the distance between two adjacent second insulating blocks 9 along the second direction, further ensuring the stability of the electrical connection between the second fine grid 4 and the second conductive element 8. At this time, along the second direction, the width S2 of the first insulating block 3 is greater than the width S1 of the second insulating block 9, where the difference between S2 and S1 is 50-250 μm. This ensures that the second fine grid 4 in the groove structure is not covered by the second insulating block 9 (or covered by the diffusion band), thus preventing poor contact.

[0075] For example, when the second region has a groove structure, D2 can be 120μm, 150μm, 155μm, 160μm, 165μm, 170μm, 175μm, 180μm, 185μm, 190μm, 195μm or 200μm, etc.

[0076] It is understood that when the second region has a groove structure, the deeper the groove structure, the more of the slurry forming the second insulating block 9 will overflow into the groove structure. Therefore, in this technical solution, the depth of the groove structure can be less than or equal to 5μm, for example, the depth of the groove is 5μm, 4μm, 3μm, 2μm or 1μm, etc., to reduce the overflow of the slurry forming the second insulating block 9.

[0077] In Figure 4, the semiconductor substrates in the first and second regions form a stepped structure. Although the schematic isolation region 2 is above the step (outside the groove), it can be understood that the isolation region 2 can also span the step surface or be below the step (inside the groove). For example, as shown in Figure 7, when the current collection layer is a transparent conductive oxide (TCO) material, the isolation region 2 can be on the step; and as another example, when the current collection layer is a doped layer, the isolation region 2 can be inside the groove. In this case, the doped layer can be a polycrystalline silicon layer, and a tunneling layer can also be present below it.

[0078] As shown in Figure 6, in some embodiments, diffusion bands 10 are formed on both sides of the first insulating block 3 along the second direction. The diffusion bands 10 include at least one material from the slurry used to form the first insulating block 3. That is, during the fabrication of the first insulating block 3, after slurry printing or laser transfer and before slurry curing, one or more organic substances in the slurry diffuse to both sides of the first insulating block 3, forming diffusion bands 10 on both sides of the first insulating block 3. The diffusion of organic substances from the slurry forming the first insulating block 3 to both sides can improve the adhesion between the first insulating block 3 and the first surface, preventing the first insulating block 3 from detaching.

[0079] Furthermore, the diffusion band 10 made of organic material can reduce the height difference between the diffusion band 10 and the first insulating block 3, which can reduce the amount of printing paste used for the main grid (first conductive element 1); or, in the absence of a main grid, it can reduce the amount of bonding layer material used at the junction of the solder ribbon and the grid line. In this embodiment, the diffusion band 10 is at least one organic material selected from epoxy resin, photocuring agent, or photoinitiator of the insulating block material, and its inorganic filler should be less than 20% wt, so as to ensure that the organic material in the first insulating block 3 can spread out and extend to the side of the first fine grid 6, and by controlling the distance between the two first insulating blocks 3 to be greater than or equal to 80 μm, the diffusion band 10 has a certain height and does not cover the first fine grid 6.

[0080] Further, as shown in Figure 7, along the second direction, the diffusion band 10 extends from the edge of the first insulating block 3 to the edge of the adjacent first fine grid 6. Specifically, along the second direction, the slurry used to form the first insulating block 3 gradually flows to contact the side of the first fine grid 6 before curing, and is blocked from further extending and flowing by the side of the first fine grid 6, thereby ensuring the stability of the electrical connection between the first fine grid 6 and the first conductive element 1.

[0081] In some embodiments, the thickness of the diffusion band 10 is less than the thickness of the first fine grid 6 along the thickness direction of the battery body. Using this technical solution, the thickness of the first fine grid 6 prevents the slurry from continuing to extend and flow, further ensuring the stability of the electrical connection between the first fine grid 6 and the first conductive element 1.

[0082] In some embodiments, as shown in FIG9, diffusion bands 10 are formed on both sides of the second insulating block 9 along the second direction. The diffusion bands 10 include at least one material in the slurry used to form the second insulating block 9. That is, during the fabrication of the second insulating block 9, after slurry printing or laser transfer and before slurry curing, one or more organic substances in the slurry diffuse to both sides of the second insulating block 9, forming diffusion bands 10 on both sides of the second insulating block 9. Along the second direction, the diffusion bands 10 extend from the edge of the second insulating block 9 to the edge of the adjacent second fine grid 4. With this configuration, since the second insulating block 9 has a certain thickness, the second conductive element 8 spanning the position where the second insulating block 9 is located and the position where the second insulating block 9 is not located has a certain height difference. Since the diffusion band 10 has a certain thickness, the formation of the diffusion band 10 can reduce the height difference of the second conductive element 8 spanning the first region and the second region, making the surface of the battery cell smoother and facilitating subsequent encapsulation. Its effect is similar to that of the diffusion band 10 between the two first insulating blocks 3, and will not be described in detail here.

[0083] In some embodiments, the material of the first insulating block 3 and / or the second insulating block 9 may include a UV-curable adhesive to ensure the formation of a diffusion band 10 of suitable thickness. Furthermore, the material of the first conductive element 1 and / or the second conductive element 8 may include a base metal paste, such as copper paste. The material of the first fine grid 6 and the second fine grid 4 may include silver, copper, etc.

[0084] As shown in Figure 8, the intersection of the second conductive element 8 and the second fine grid 4 has a side protrusion 81 protruding along a first direction. That is, along the first direction, the width of the second conductive element 8 at the location where the side protrusion 81 is located is greater than the width of the second conductive element 8 at other locations excluding the side protrusion 81. This arrangement increases the contact area between the second conductive element 8 and the second fine grid 4, thereby reducing the transmission resistance between them, decreasing current loss, and improving the photoelectric conversion efficiency of the back contact battery. Furthermore, in this technical solution, when diffusion bands 10 are present on both sides of the second fine grid 4, the diffusion bands 10 can limit the flow distance of the slurry forming the second conductive element 8 along the first direction from being too large, thus preventing the formed side protrusion 81 from becoming too wide.

[0085] In some embodiments, as shown in FIG8, a recess is formed at the intersection of the top of the side protrusion 81 and the second fine gate 4 along the first direction. Specifically, the width of the intersection of the side protrusion 81 and the second fine gate 4 along the first direction is appropriately reduced, which saves more raw materials of the second conductive element 8 while ensuring a reduction in transmission resistance. Similarly, a side protrusion (not shown) protruding along the first direction is also provided at the intersection of the first conductive element 1 and the first fine gate 6. Its structure and effect are similar to those of the side protrusion 81, and will not be described again here.

[0086] In other embodiments, as shown in FIG10, the first fine grid 6 includes first thickened segments 61 spaced apart along a first direction. Along a second direction, the width of the first thickened segments 61 is greater than the width of the remaining portion of the first fine grid 6 excluding the first thickened segments 61. That is, the first thickened segments 61 are provided at the position where the first fine grid 6 connects to the first conductive element 1. These first thickened segments 61 can be integrally formed with the remaining portion of the first fine grid 6 excluding the first thickened segments 61, or they can be formed separately. Using this technical solution, the provision of the first thickened segments 61 can increase the contact area between the first fine grid 6 and the first conductive element 1, thereby reducing the transmission resistance between the first conductive element 1 and the first fine grid 6, reducing current loss, and improving the photoelectric conversion efficiency of the back contact battery.

[0087] Further, as shown in Figure 10, along the second direction, the distance between the edge of the first thickened segment 61 and its adjacent first insulating block 3 is D4, where D4 ≥ 50 μm. This setting provides a safe distance for slurry flow, preventing the slurry forming the first insulating block 3 from flowing into and covering the first thickened segment 61, ensuring the stability of the electrical connection between the first thickened segment 61 and the first conductive element 1, thereby improving the stability of the back contact battery performance. For example, D4 ​​can be 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, or 100 μm, etc.

[0088] Furthermore, as shown in Figure 11, the second fine grid 4 includes second thickened sections 41 spaced apart along a first direction. Along a second direction, the width of the second thickened sections 41 is greater than the width of the rest of the second fine grid 4 excluding the second thickened sections 41. That is, the second thickened sections 41 are provided at the location where the second fine grid 4 connects to the second conductive element 8. These second thickened sections 41 can be integrally formed with the rest of the second fine grid 4 excluding the second thickened sections 41, or they can be formed separately. Using this technical solution, the provision of the second thickened sections 41 increases the contact area between the second fine grid 4 and the second conductive element 8, thereby reducing the transmission resistance between the second conductive element 8 and the second fine grid 4, reducing current loss, and improving the photoelectric conversion efficiency of the back contact battery.

[0089] Further, as shown in Figure 11, along the second direction, the distance between the edge of the second thickened segment 41 and its adjacent second insulating block 9 is D3, where D3 ≥ 50 μm. This setting provides a safe distance for slurry flow, preventing the slurry forming the second insulating block 9 from flowing into and covering the second thickened segment 41, ensuring the stability of the electrical connection between the second thickened segment 41 and the second conductive element 8, thereby improving the stability of the back contact battery performance. For example, D3 can be 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, or 100 μm, etc.

[0090] In some embodiments, the first conductive element 1 is the main grid, and the back contact battery is a battery with a main grid. The organic matter in the slurry forming the main grid and the organic matter in the slurry forming the first insulating block 3 are mutually soluble. By adopting this technical solution, after the organic matter in the slurry of the main grid and the organic matter in the slurry of the first insulating block 3 are mutually soluble, the adhesion between the first conductive element 1 and the first insulating block 3 is stronger, further preventing the first conductive element 1 from falling off.

[0091] The semiconductor substrate can be made of materials such as silicon (Si), germanium (Ge), or gallium arsenide (GaAs). Obviously, in terms of conductivity type, the semiconductor substrate can be an intrinsically conductive substrate, an n-type conductive substrate, or a p-type conductive substrate. Optionally, the semiconductor substrate can be a p-type conductive substrate or an n-type conductive substrate. Compared to intrinsically conductive substrates, p-type or n-type conductive substrates have better conductivity, resulting in a lower bulk resistivity in the final solar cell, thereby improving the efficiency of the solar cell.

[0092] Furthermore, in some embodiments, the back contact battery further includes a first doped layer and a second doped layer, wherein the first doped layer is formed at least in a first region and the second doped layer is formed at least in a second region. For example, the first doped layer is formed in the first region and the isolation region 2, and the second doped layer is formed in the second region and the isolation region 2, with the first and second doped layers overlapping within the isolation region 2. Alternatively, the first doped layer may be formed only in the first region and the second doped layer only in the second region. The first doped layer can be additionally formed on the semiconductor substrate using deposition techniques, or it can be formed within the semiconductor substrate using diffusion, ion implantation, or other methods.

[0093] Regarding the conductivity type, the first doped layer can be an n-type doped layer and the second doped layer can be a p-type doped layer; or, the first doped layer can be a p-type doped layer and the second doped layer can be an n-type doped layer.

[0094] Furthermore, the materials of the first and second doped layers can be silicon (Si), germanium (Ge), silicon carbide (SiCx), or gallium arsenide (GaAs), etc. Taking silicon (Si) as an example where both the first and second doped layers are made of silicon, the first doped layer can be one or more of doped polycrystalline silicon, doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon. The second doped layer can also be one or more of doped polycrystalline silicon, doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon.

[0095] When the first doped layer is one or more of doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon, and the second doped layer is one or more of doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon, the first doped layer is formed in the first region and the isolation region 2, and the second doped layer is formed in the second region and the isolation region 2, with the first and second doped layers overlapping within the isolation region 2. A first current collecting layer 7 is disposed on the side of the first doped layer facing away from the semiconductor substrate, and a second current collecting layer 5 is disposed on the side of the second doped layer facing away from the semiconductor substrate. Both the first and second current collecting layers are transparent conductive layers, and are disconnected and do not contact each other within the isolation region 2. The transparent conductive layer has high conductivity, which can promptly discharge the collected charge carriers, reducing the charge carrier recombination rate, and can also reduce the contact resistance between the first and second doped layers and the electrodes.

[0096] Regarding the aforementioned transparent conductive layer, this application does not specifically limit the material and thickness of the transparent conductive layer. Exemplarily, the material of the transparent conductive layer may include at least one of fluorine-doped tin oxide, aluminum-doped zinc oxide, tin-doped indium oxide, tungsten-doped indium oxide, molybdenum-doped indium oxide, cerium-doped indium oxide, indium hydroxide, titanium nitride, cadmium oxide, cuprous oxide, and fluorine-doped zinc oxide. The transparent conductive layer may be a single-layer thin film or a multilayer thin film. Exemplarily, the thickness of the transparent conductive layer may be greater than or equal to 10 nm and less than or equal to 100 nm.

[0097] Furthermore, when both the first doped layer and the second doped layer are doped polysilicon layers, the first doped layer is formed only in the first region, and the second doped layer is formed only in the second region; alternatively, the first doped layer is formed in the first region and the isolation region 2, and the second doped layer is formed in the second region and the isolation region 2. The first and second doped layers overlap within the isolation region 2, and an opening penetrating the thickness of both the first and second doped layers is provided within the isolation region 2 to isolate the first and second doped layers and prevent leakage. In this embodiment, the first current collecting layer 7 and the second current collecting layer 5 are doped semiconductor layers, and their doping types are opposite. That is, the first current collecting layer 7 is the first doped layer, and the second current collecting layer 5 is the second doped layer.

[0098] Furthermore, this application also provides a photovoltaic module including the back contact cell provided in any of the above embodiments. The back contact cell includes a first conductive element 1 that extends along a second direction and is directly physically and electrically connected to the first fine grid 6, or electrically connected to the first fine grid 6 through a bonding layer. Compared with the prior art, the beneficial effects of the photovoltaic module provided in this application are the same as those of the back contact cell described above, and will not be repeated here.

[0099] In this photovoltaic module, the first conductive element 1 is a solder ribbon, which connects at least two back-contact cells to form a cell structure (i.e., a cell string structure). In this case, the back-contact cell is a gridless cell, and the solder ribbon is electrically connected to the first fine grid 6 through a bonding layer. The bonding layer can specifically be solder or conductive adhesive. Using this technical solution, the solder ribbon is directly electrically connected to the first fine grid 6, achieving the effect of reducing shading and resistance loss. When the first conductive element is a grid, the photovoltaic module will also include a solder ribbon, which needs to be welded to the grid using a bonding material, thereby enabling multiple cells at the module end to be connected in series or parallel.

[0100] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0101] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the appended claims.

Claims

1. A back-contact battery, comprising: The battery body includes a first surface and a second surface that are disposed opposite to each other; A plurality of first fine gates and a plurality of second fine gates are disposed on the first surface; The first fine grid and the second fine grid extend along a first direction and are alternately spaced along a second direction; the first direction intersects the second direction; Multiple first insulating blocks are arranged at intervals along the second direction and respectively cover multiple second fine grids; along the second direction, the distance between the edges of adjacent first insulating blocks is D1, where D1≥80μm.

2. The back contact cell of claim 1, wherein, Along the thickness direction of the battery body, the thickness of the first insulating block is h1, where 20μm≤h1≤100μm.

3. The back contact cell of claim 1, wherein, Along the thickness direction of the battery body, the thickness of the first insulating block is h1, the thickness of the first fine grid is h2, and h1 / h2≤4.

4. The back contact cell of claim 1, wherein, The back contact battery also includes a first conductive element that extends along the second direction and is electrically connected to the first fine grid.

5. The back contact cell of claim 4, wherein, The first conductive element has a side protrusion that protrudes along the first direction at the intersection with the first fine grid.

6. The back contact cell of claim 5, wherein, A recess is formed at the intersection of the top of the side protrusion and the first fine grid.

7. The back contact cell of claim 4, wherein, The first conductive element is the main gate; and the organic matter in the slurry forming the main gate is mutually soluble with the organic matter in the slurry forming the first insulating block.

8. The back contact cell of claim 1, wherein, The back contact battery also includes a plurality of second insulating blocks, which are spaced apart along the second direction and respectively cover a plurality of first fine grids; along the second direction, the distance between the edges of adjacent second insulating blocks is D2, D2≥80μm and / or D2≥D1.

9. The back contact cell of claim 8, wherein, The back contact battery also includes a second conductive element that extends along the second direction and is electrically connected to the second fine grid.

10. The back contact cell of claim 1, wherein, The back contact battery further includes a plurality of second insulating blocks, which are spaced apart along the second direction and respectively cover the plurality of first fine grids; along the second direction, the width of the second insulating block is S1, and the width of the first insulating block is S2, wherein S2 is greater than S1; and / or, S2 is 50μm-250μm larger than S1.

11. The back contact cell of claim 10, wherein, The first surface has a first region and a second region alternately arranged along a second direction, the first region and the second region extending along the first direction, the first fine grid being disposed in the first region, and the second fine grid being disposed in the second region; the second region is a groove structure, the groove structure being recessed relative to the first region toward the second surface.

12. The back contact cell of claim 8 or 11, wherein, Along the second direction, the distance between the edges of adjacent second insulating blocks is D2, D2 > D1, and / or, D2 ≥ 120 μm.

13. The back contact cell of claim 1, wherein, The battery body includes: a semiconductor substrate, a first current collecting layer and a second current collecting layer, wherein the first current collecting layer and the second current collecting layer extend along the first direction and are alternately spaced along the second direction; a first fine gate is disposed on the first current collecting layer and a second fine gate is disposed on the second current collecting layer, and the types of current collected by the first current collecting layer and the second current collecting layer are opposite. An isolation region extending along the first direction is provided between adjacent first current collecting layers and second current collecting layers; along the second direction, the isolation region between adjacent first current collecting layers and second current collecting layers is at least partially covered by the first insulating block.

14. The back contact cell of claim 13, wherein, Along the second direction, the width of the first insulating block extending onto the adjacent first current collecting layer is L1, where L1 ≥ 40 μm.

15. The back contact cell of claim 13, wherein, The first current collecting layer and the second current collecting layer are transparent conductive layers; or, the first current collecting layer and the second current collecting layer are doped semiconductor layers, and the doping types of the two are opposite.

16. The back contact cell of claim 1, wherein, Along the second direction, diffusion bands are formed on both sides of the first insulating block, the diffusion bands comprising at least one material in the slurry used to form the first insulating block; Along the second direction, the diffusion band extends from the edge of the first insulating block to the edge of the first fine grid adjacent to it.

17. The back contact cell of claim 16, wherein, Along the thickness direction of the battery body, the thickness of the diffusion band is less than the thickness of the first fine grid.

18. The back contact cell of claim 1, wherein, The first fine grid includes first thickened segments spaced apart along the first direction, and along the second direction, the width of the first thickened segments is greater than the width of the remaining portion of the first fine grid excluding the first thickened segments; and / or, the second fine grid includes second thickened segments spaced apart along the first direction, and along the second direction, the width of the second thickened segments is greater than the width of the remaining portion of the second fine grid excluding the second thickened segments.

19. The back contact cell of claim 18, wherein, The back contact battery also includes a plurality of second insulating blocks, which are spaced apart along the second direction and respectively cover a plurality of the first fine grids; Along the second direction, the distance between the edge of the second thickened segment and the adjacent second insulating block is D3, where D3 ≥ 50 μm; and / or, along the second direction, the distance between the edge of the first thickened segment and the adjacent first insulating block is D4, where D4 ≥ 50 μm.

20. A photovoltaic module comprising a back contact cell as claimed in any one of claims 1-6 and 8-19; the back contact cell further comprising a first conductive element extending along a second direction and being physically and electrically connected to the first grid, or electrically connected to the first grid via a bonding layer.

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