A back contact solar cell, a photovoltaic module and a method for manufacturing the same

Abstract

The application discloses a back contact solar cell, a photovoltaic module and a preparation method thereof. The back contact solar cell can include: a cell main body structure, a back surface of the cell main body structure is alternately arranged with a first conductive area and a second conductive area along a first direction, adjacent first conductive areas and second conductive areas are electrically isolated, the first conductive area and the second conductive area both extend along a second direction, and the second direction is perpendicular to the first direction; a plurality of first conductive pieces, the plurality of first conductive pieces are arranged in the first conductive area and the second conductive area and extend along the second direction, or each first conductive piece extends along the first direction and is connected with a plurality of first conductive areas or a plurality of second conductive areas; and a plurality of second conductive pieces arranged on a front surface of the cell main body structure, the extension direction of the plurality of second conductive pieces is consistent with the extension direction of the plurality of first conductive pieces. The structure can reduce the risk of warping of the back contact solar cell, thereby reducing the risk of fragmentation of the back contact solar cell in the packaging process.

Description

Technical Field

[0001] This invention relates to a back-contact solar cell, a photovoltaic module, and a method for manufacturing the same. Background Technology

[0002] For back-contact solar cells, especially those with a fine-grid interconnect structure (in which each conductive region's conductive seed layer is connected to a conductive wire or solder ribbon extending along the conductive region's direction), solder ribbons or conductive wires are used to connect the fine grid or conductive seed layer. During the soldering process, due to the different coefficients of thermal expansion between the crystalline silicon substrate, the conductive seed layer / fine grid, and the solder ribbon / conductive wire, the heat generated during soldering causes varying degrees of thermal stress in these materials. During cooling, these materials shrink at different rates, leading to warping of the crystalline silicon substrate, i.e., warping of the back-contact solar cell. Warped back-contact solar cells are prone to breakage during subsequent encapsulation. Summary of the Invention

[0003] In view of this, the present invention provides a back-contact solar cell, a photovoltaic module and a method for manufacturing the same. The back-contact solar cell uses a plurality of first conductive elements and a plurality of second conductive elements in cooperation. The plurality of first conductive elements and the plurality of second conductive elements apply opposite stresses to the back-contact solar cell, and the plurality of first conductive elements and the plurality of second conductive elements restrain each other, which can reduce the risk of warping of the back-contact solar cell, thereby reducing the risk of breakage of the back-contact solar cell during subsequent packaging.

[0004] Specifically, the present invention provides the following technical solutions: In a first aspect, the present invention provides a back-contact solar cell, comprising: A battery body structure, wherein a first conductive region and a second conductive region of opposite conductivity types are alternately arranged on the back side of the battery body structure along a first direction, adjacent first conductive regions and second conductive regions are electrically isolated, and both the first conductive region and the second conductive region extend along a second direction, the second direction being perpendicular to the first direction; A plurality of first conductive elements, wherein the plurality of first conductive elements are respectively disposed in the first conductive region and the second conductive region and extend along the second direction, or each first conductive element extends along the first direction and connects to a plurality of first conductive regions or a plurality of second conductive regions; and A plurality of second conductive elements are disposed on the front side of the battery main body structure, wherein the extending direction of the plurality of second conductive elements is consistent with the extending direction of the plurality of first conductive elements.

[0005] Secondly, embodiments of the present invention provide a photovoltaic module, comprising: a backsheet, a lower encapsulating film, a cell array, an upper encapsulating film, and a cover plate stacked from bottom to top. The battery array includes multiple back-contact solar cells provided in the first aspect embodiment or back-contact cell sheets cut from the back-contact solar cells provided in the first aspect embodiment, connected in series and / or in parallel.

[0006] Thirdly, embodiments of the present invention provide a method for preparing a back-contact solar cell, comprising: Step 1: Provide a battery body structure, wherein a first conductive region and a second conductive region are alternately arranged on the back side of the battery body structure along a first direction, adjacent first conductive regions and second conductive regions are electrically isolated, and both the first conductive region and the second conductive region extend along a second direction, which is perpendicular to the first direction; Step 2: Lay a first conductive element extending along the second direction in each of the first conductive area and the second conductive area, or lay a first conductive element extending along the second direction for connecting multiple first conductive areas or multiple second conductive areas; Step 3: Lay multiple second conductive elements on the front side of the battery main body structure, wherein the extension direction of the multiple second conductive elements is consistent with the extension direction of the multiple first conductive elements; Step 4: Simultaneously weld the second conductive component and the first conductive component.

[0007] The technical solution of the first aspect of the above invention has the following advantages or beneficial effects: The back-contact solar cell provided in this invention has a back-contact solar cell with alternating first and second conductive regions arranged along a first direction on the back side of the main cell structure, both extending along a second direction perpendicular to the first direction. Multiple first conductive elements disposed on the back side of the main cell structure and multiple second conductive elements disposed on the front side of the main cell structure cooperate, with the extension directions of the multiple second conductive elements consistent with those of the multiple first conductive elements. On one hand, the force exerted on the main cell structure by the contraction of the first conductive elements is opposite to the force exerted on the main cell structure by the contraction of the second conductive elements, thus canceling each other out and reducing the risk of warping of the main cell structure. On the other hand, the multiple first and second conductive elements can mutually restrain each other, further reducing the risk of warping of the main cell structure. This reduces the risk of breakage of the back-contact solar cell during subsequent encapsulation. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the structure of a back-contact solar cell where the back-contact solar cell warps after the first conductive component is welded to the main body structure. Figure 2 This is a schematic diagram of the back structure of a first structure of the back contact solar cell body structure provided in an embodiment of the present invention. Figure 3 Figure (A) is a schematic diagram of the back structure of a second type of back-contact solar cell body structure provided according to an embodiment of the present invention; Figure (B) is a schematic diagram of the back structure of a third type of back-contact solar cell body structure provided according to an embodiment of the present invention. Figure 4 Figure (A) is a schematic diagram of the back structure of the back contact solar cell provided in an embodiment of the present invention, showing a first relative relationship between the battery body structure and the first conductive element; Figure (B) is a schematic diagram of the front structure of the back contact solar cell provided in an embodiment of the present invention, showing a first relative relationship between the battery body structure and the first conductive element and the second conductive element; Figure (C) is a schematic diagram of the front structure of the back contact solar cell provided in an embodiment of the present invention, showing a second relative relationship between the battery body structure and the first conductive element and the second conductive element; Figure (D) is a schematic diagram of the front structure of the back contact solar cell provided in an embodiment of the present invention, showing a third relative relationship between the battery body structure and the first conductive element and the second conductive element. Figure 5 Figure (A) is a schematic diagram of the back structure of the back contact solar cell body structure provided according to an embodiment of the present invention, showing a first structure and a second relative relationship between the first conductive element and the first conductive element; Figure (B) is a schematic diagram of the front structure of the back contact solar cell body structure provided according to an embodiment of the present invention, showing a first structure and a second relative relationship between the first conductive element and the second conductive element; Figure (C) is a schematic diagram of the front structure of the back contact solar cell body structure provided according to an embodiment of the present invention, showing a second structure and a second relative relationship between the first conductive element and the second conductive element; Figure (D) is a schematic diagram of the front structure of the back contact solar cell body structure provided according to an embodiment of the present invention, showing a third structure and a second relative relationship between the first conductive element and the second conductive element. Figure 6 This is a schematic diagram of the back structure of a second or third structure of the battery body of a back-contact solar cell provided according to an embodiment of the present invention, showing a second relative relationship between the back structure and the first conductive element. Figure 7 This is a three-dimensional structural schematic diagram of a back-contact solar cell provided according to an embodiment of the present invention; Figure 8 This is a cross-sectional structural schematic diagram of a back-contact solar cell with a first structure provided according to an embodiment of the present invention; Figure 9 This is a cross-sectional structural schematic diagram of a back-contact solar cell with a second structure provided according to an embodiment of the present invention; Figure 10 This is a schematic cross-sectional view of a third type of back-contact solar cell provided according to an embodiment of the present invention. Figure 11 This is a cross-sectional structural diagram of a fourth type of back-contact solar cell provided according to an embodiment of the present invention; Figure 12 This is a partial three-dimensional schematic diagram of a string of back-contact solar cells provided in an embodiment of the present invention.

[0009] The attached figures are labeled as follows: 10-Battery main structure; 11-First conductive region; 111-First carrier collection layer; 112-First conductive seed layer; 12-Second conductive region; 121-Second carrier collection layer; 122-Second conductive seed layer; 13-Groove; 14-Passivation antireflection layer; 15-Crystal silicon substrate; 16-Isolation region; 20-First conductive element; 30-Second conductive element; 40-Insulating element; D1-First direction; D2-Second direction. Detailed Implementation

[0010] For gridless back-contact solar cells, such as Figure 1 As shown, its first conductive region 11 (such as a P-type functional region) and second conductive region 12 (such as an N-type functional region) are generally alternately arranged along the first direction D1 on the back of the battery body structure 10. Each first conductive region 11 is provided with a first conductive seed layer 112 or a fine grid extending along the second direction D2, and each second conductive region 12 is provided with a second conductive seed layer 122 or a fine grid extending along the second direction D2. In the prior art, for this gridless back-contact solar cell, it either adopts... Figure 1 Scheme A shown involves laying and soldering a first conductive element 20 onto each first conductive seed layer 112 and each second conductive seed layer 122, or onto each fine grid. The extension direction of the first conductive element 20 is the second direction D2. Alternatively, it may employ... Figure 1In scheme B shown, a first conductive element 20 is connected in series with multiple first conductive seed layers 112 or multiple second conductive seed layers 122. An insulating element 40 is provided between the first conductive element 20 connected to the multiple first conductive seed layers 112 and the second conductive seed layers 122, and an insulating element 40 is also provided between the first conductive element 20 connected to the multiple second conductive seed layers 122 and the first conductive seed layer 112. In the prior art, during the welding of the first conductive element 20 to a gridless back-contact solar cell, due to the different coefficients of thermal expansion between the cell body structure 10 and the first conductive element 20, the welding heat causes differential expansion between the cell body structure 10 and the first conductive element 20. After cooling, regardless of whether it is scheme A or scheme B, the shrinkage strength of the first conductive element 20 is greater than that of the cell body structure 10, resulting in warping of the gridless back-contact solar cell. This warping mainly manifests as an upward bulge in the middle region when the light-receiving surface of the gridless back-contact solar cell is placed upwards.

[0011] To address the aforementioned problems in the prior art, embodiments of the present invention provide a back-contact solar cell, a photovoltaic module, and a method for fabricating the same. This back-contact solar cell utilizes a first conductive element 20 disposed on the back side of the cell's main structure in conjunction with a second conductive element 30 disposed on the front side of the cell's main structure to prevent warping of the back-contact solar cell, particularly preventing warping of back-contact solar cells without a main grid.

[0012] In the embodiments of the present invention, the outer side of a structure is defined with reference to the crystalline silicon substrate 15. Specifically, the side of the structure away from the crystalline silicon substrate 15 is the outer side of the structure.

[0013] In the embodiments of the present invention, one structure is located on another structure, which generally means that the one structure is fixed on the other structure, the one structure can be directly on another element, or there is an intermediate structure between the one structure and the other structure.

[0014] It should be noted that the terms "first," "second," etc., 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. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0015] It is worth noting that, in the embodiments of the present invention, the back side of the crystalline silicon substrate 15 generally refers to the main surface of the crystalline silicon substrate 15 facing away from sunlight during the operation of the photovoltaic module encapsulating the crystalline silicon solar cell. The main surface of the crystalline silicon substrate 15 facing sunlight is the front side of the crystalline silicon substrate 15.

[0016] Specifically, embodiments of the present invention provide a back-contact solar cell. For example... Figures 2 to 11 As shown, the back-contact solar cell may include: a main cell structure 10, a plurality of first conductive elements 20 disposed on the back side of the main cell structure 10, and a plurality of second conductive elements 30 disposed on the front side of the main cell structure 10.

[0017] More specifically, such as Figures 2 to 11 As shown, the battery main body structure 10 has a first conductive region 11 and a second conductive region 12 with opposite conductivity types arranged alternately on the back side of the battery main body structure 10 along the first direction D1. The adjacent first conductive regions 11 and second conductive regions 12 are electrically isolated. The first conductive regions 11 and the second conductive regions 12 both extend along the second direction D2, which is perpendicular to the first direction D1. The relationship between the multiple first conductive elements 20 and the first conductive region 11 and the second conductive region 12 can be twofold. The first relationship is as follows: Figure 4 (A) and Figure 6 As shown, multiple first conductive elements 20 are respectively disposed in the first conductive region 11 and the second conductive region 12 and extend along the second direction D2, that is, the multiple first conductive elements 20 correspond one-to-one with the first conductive region 11 and the second conductive region 12. Second relationship: as... Figure 5 As shown in (A), each first conductive element 20 extends along a first direction D1 and connects to a plurality of first conductive regions 11 or a plurality of second conductive regions 12. It can be understood that, for this second relationship, as... Figure 5 As shown in (A), an insulating element 40 is provided between the first conductive element 20, which is connected in series with multiple first conductive regions 11, and the second conductive region 12, and the first conductive element 20, which is connected in series with multiple second conductive regions 12, and the first conductive region 11, so as to avoid short circuit between the first conductive region 11 and the second conductive region 12.

[0018] Regardless of whether the relationship between the multiple first conductive elements 20 and the first conductive region 11 and the second conductive region 12 is the first relationship described above or the second relationship described above, such as... Figure 4 (B) Figure 4 (C) Figure 4 (D) Figure 5 (B) Figure 5 (C) and Figure 5 As shown in (D), the extension direction of the plurality of second conductive elements 30 disposed on the front side of the battery main body structure 10 is consistent with the extension direction of the plurality of first conductive elements 20.

[0019] The back-contact solar cell provided in this embodiment of the invention has a first conductive region 11 and a second conductive region 12 alternately arranged along a first direction D1 on the back side of the main cell structure 10, with both the first conductive region 11 and the second conductive region 12 extending along a second direction D2 perpendicular to the first direction D1. Furthermore, multiple first conductive elements 20 disposed on the back side of the main cell structure 10 and multiple second conductive elements 30 disposed on the front side of the main cell structure 10 cooperate, with the extension directions of the multiple second conductive elements 30 being consistent with the extension directions of the multiple first conductive elements 20. On one hand, the force exerted on the main cell structure 10 by the contraction of the first conductive elements 20 is opposite to the force exerted on the main cell structure 10 by the contraction of the second conductive elements 30, thus canceling each other out and reducing the risk of warping of the main cell structure 10. On the other hand, the multiple first conductive elements 20 and the multiple second conductive elements 30 can mutually restrain each other, further reducing the risk of warping of the main cell structure 10. This reduces the risk of breakage of the back-contact solar cell during subsequent encapsulation, improves the yield of photovoltaic modules made from back-contact solar cells, and better adapts to industrialization needs and structural practicality.

[0020] In addition, the structure of the back-contact solar cell provided in this embodiment of the invention can ensure the light utilization rate and aesthetics of the back-contact solar cell.

[0021] The battery main structure 10 is generally formed by fabricating various functional layers on a main surface of a crystalline silicon substrate 15. The crystalline silicon substrate 15 can be a P-type or an N-type crystalline silicon substrate. The first conductive region 11 and the second conductive region 12, with opposite conductivity types, are formed by creating differentiated functional layers on the main surface of the crystalline silicon substrate 15 corresponding to the first conductive region 11 (i.e., the first region of the crystalline silicon substrate 15) and on the main surface of the crystalline silicon substrate 15 corresponding to the second conductive region 12 (i.e., the second region of the crystalline silicon substrate 15, which does not overlap with the first region). For example, the first conductive region 11 can be an N-type conductive region, and correspondingly, the second conductive region 12 is a P-type conductive region; or, the first conductive region 11 can be a P-type conductive region, and correspondingly, the second conductive region 12 is an N-type conductive region.

[0022] The relationship between the first conductive region 11 and the second conductive region 12 of the battery main structure 10 can be described as follows: Figure 2 , Figure 4 and Figure 5 As shown, both the first conductive region 11 and the second conductive region 12 are elongated strip structures extending along the second direction D2, or they can be like... Figure 3 and Figure 6 As shown, the first conductive region 11 and the second conductive region 12 have an interdigitated structure along the first direction D1. It should be noted that, as... Figure 3 and Figure 6As shown, for the first conductive region 11 and the second conductive region 12 with their intersecting structures, their extension direction is still the second direction D2. In addition, electrical isolation between adjacent first conductive regions 11 and second conductive regions 12 is generally achieved by setting an isolation region 16 between adjacent first conductive regions 11 and second conductive regions 12.

[0023] In this embodiment of the invention, specifically for each functional layer formed on the crystalline silicon substrate 15, such as... Figure 2 , Figure 3 (A) Figure 3 (B) and Figures 8 to 11 As shown, the battery main structure 10 may include: a first carrier collection layer 111 disposed on the first conductive region 11 and a first conductive seed layer 112 or a first grid line disposed outside the first carrier collection layer 111; a second carrier collection layer 121 disposed on the second conductive region 12 and a second conductive seed layer 122 or a second grid line disposed outside the second carrier collection layer 121.

[0024] The first carrier collecting layer 111 can be an N-type carrier collecting layer, making the first conductive layer 11 an N-type conductive layer. Correspondingly, the second carrier collecting layer 121 is a P-type carrier collecting layer, making the second conductive layer 12 a P-type conductive layer. Alternatively, the first carrier collecting layer 111 can be a P-type carrier collecting layer, making the first conductive layer 11 a P-type conductive layer. Correspondingly, the second carrier collecting layer 121 is an N-type carrier collecting layer, making the second conductive layer 12 an N-type conductive layer.

[0025] Specifically, the P-type carrier collection layer can have two structures. For example, the first structure of the P-type carrier collection layer can be a diffusion layer containing P-type dopant atoms (boron and / or antimony, etc.) formed on a portion of the main surface of the crystalline silicon substrate 15. The second structure of the P-type carrier collection layer can be a tunneling oxide layer and a P-type doped polysilicon layer containing P-type dopant atoms (boron or antimony, etc.) stacked from the inside out. The N-type carrier collection layer generally includes a tunneling oxide layer and an N-type doped polysilicon layer containing N-type dopant atoms (phosphorus and / or arsenic, etc.) stacked from the inside out. Both the P-type and N-type doped polysilicon layers can be single-layer or multi-layer structures.

[0026] Based on the first carrier collection layer 111 and the second carrier collection layer 121, the battery main body structure 10 may further include: a passivation layer (such as an aluminum oxide layer) and an anti-reflection layer (such as a composite silicon nitride layer) disposed on the outside of the first carrier collection layer 111 and the second carrier collection layer 121.

[0027] Furthermore, the first conductive seed layer 112 and the second conductive seed layer 122 are generally formed by printing a paste containing conductive metals (such as silver, copper, etc.) onto the conductive region and then curing it. The first gate line and the second gate line are generally formed by printing and sintering metal paste. The first conductive seed layer 112 and the second conductive seed layer 122 are generally used in conjunction with each other, as are the first gate line and the second gate line. Understandably, for the battery body structure 10 including the passivation layer and the antireflection layer, the first conductive seed layer 112 and the second conductive seed layer 122, or the first gate line and the second gate line, pass through the passivation layer and the antireflection layer and are electrically connected to the first carrier collection layer 111 and the second carrier collection layer 121, respectively. It is worth noting that the first gate line and the second gate line are generally fine gates; that is, the first gate line is a fine gate disposed in the first conductive region 11, and the second gate line is a fine gate disposed in the second conductive region 12. In addition, the conductive components involved in the embodiments of the present invention (such as the first conductive component 20 and the second conductive component 30) are generally conductive wires or solder strips electrically connected to the conductive seed layer or grid lines disposed on the conductive layer, which are used to conduct the current of the back contact solar cell.

[0028] Based on the above-mentioned structure of the first conductive seed layer 112 and the second conductive seed layer 122 or the first gate line and the second gate line, the first conductive element 20 disposed in the first conductive region 11 is electrically connected to the first conductive seed layer 112 or the first gate line of the first conductive region 11; the second conductive element 30 disposed in the second conductive region 12 is electrically connected to the second conductive seed layer 122 or the second gate line of the second conductive region 12.

[0029] There can be multiple relationships between the first conductive seed layer 112 or the first gate line and the first conductive region 11, and between the second conductive seed layer 122 or the second gate line and the second conductive region 12.

[0030] Specifically, for the case where the first conductive region 11 and the second conductive region 12 are elongated structures, such as... Figure 2 As shown, the first conductive seed layer 112 or the first gate line extends along the second direction D2; the second conductive seed layer 122 or the second gate line extends along the second direction D2.

[0031] For the structure in which the first conductive region 11 and the second conductive region 12 are arranged in an interlaced pattern, it can be as follows: Figure 3 As shown in (A), a first conductive seed layer 112 or a first gate line extending along the first direction D1 is arranged on each first conductive region 11 along the second direction D2, and a second conductive seed layer 122 or a second gate line extending along the first direction D1 is arranged on each second conductive region 12 along the second direction D2; alternatively, as shown in (A), a first conductive seed layer 112 or a first gate line extending along the first direction D1 is arranged on each second conductive region 12. Figure 3As shown in (B), a first conductive seed layer 112 (or a first gate line) extending along the first direction D1 and a first conductive seed layer 112 (or a first gate line) extending along the second direction D2 are arranged on each first conductive region 11. A second conductive seed layer 122 (or a second gate line) extending along the first direction D1 and a second conductive seed layer 122 (or a second gate line) extending along the second direction D2 are arranged on each second conductive region 12.

[0032] Regardless of whether the first conductive region 11 and the second conductive region 12 are elongated structures or intersecting structures, based on any structure of the first conductive seed layer 112 and the second conductive seed layer 122, or any structure of the first gate line and the second gate line, the multiple first conductive elements 20 can be connected to the first conductive region 11 and the second conductive region 12. Figure 4 (A) and Figure 6 The first type of relationship is shown above. It can be understood that, as... Figure 6 As shown, the first conductive region 11 and the second conductive region 12 refer to a cross structure. In the first relationship between the multiple first conductive elements 20 and the first conductive region 11 and the second conductive region 12, the first conductive element 20 on each first conductive region 11 is connected in series with the first conductive seed layer 112 or the first gate line arranged along the second direction on the first conductive region 11; the first conductive element 20 on each second conductive region 12 is connected in series with the second conductive seed layer 122 or the second gate line arranged along the second direction on the second conductive region 12.

[0033] Furthermore, since the first conductive region 11 and the second conductive region 12 are elongated structures, the multiple first conductive elements 20 can also be spaced with the first conductive region 11 and the second conductive region 12. Figure 5 The second relationship mentioned above is shown in (A).

[0034] The aforementioned battery main structure 10 can meet the needs of different back-contact solar cells, making the back-contact solar cell provided in this embodiment of the invention more practical and meeting more customer needs.

[0035] In embodiments of the present invention, based on any of the above structures, such as Figure 10 and Figure 11 As shown, the battery main body structure 10 may further include: a passivation antireflection layer 14 disposed on the front side of the battery main body structure 10, and a second conductive element 30 disposed above the passivation antireflection layer 14. Figure 11 (as shown) or below ( Figure 10 As shown in the figure, this effectively improves the light utilization rate of back-contact solar cells.

[0036] In addition, in one embodiment of the present invention, the battery main body structure 10 may further include a passivation antireflection layer disposed on the back side outside the first carrier collection layer 111 and the second carrier collection layer 121. Generally, for structures including the first conductive seed layer 112 and the second conductive seed layer 122, the passivation antireflection layer on the back side does not cover the first conductive seed layer 112 and the second conductive seed layer 122, so as to further improve the light utilization rate of the back contact solar cell.

[0037] The relationship between the second conductive element 30 and the first conductive element 20 can be described as follows: Figure 4 (B) Figure 4 (C) Figure 5 (B) and Figure 5 As shown in (C), the position of the second conductive element 30 can correspond to that of the first conductive element 20; or it can be as follows: Figure 4 (D) and Figure 5 As shown in (D), the second conductive element 30 is located between two adjacent first conductive elements 20. Preferably, the position of the second conductive element 30 can correspond to the first conductive element 20, so that both ends of the second conductive element 30 can be welded to the first conductive element 20, which can improve the correction capability of the second conductive element 30 for the battery cell and reduce the risk of the second conductive element 30 desoldering later.

[0038] In a preferred embodiment, in the thickness direction of the battery body structure 10, each second conductive element 30 corresponds to one first conductive element 20, and each second conductive element 30 corresponds to a different first conductive element 20. More specifically, this structure can be as follows: Figure 4 As shown in (A), the second conductive element 30 corresponds one-to-one with the first conductive element 20; alternatively, as shown in Figure 1. Figure 4 As shown in (B), the second conductive element 30 is provided only for a portion of the first conductive element 20. Preferably, the second conductive element 30 is provided only for a portion of the first conductive element 20 to reduce the number of second conductive elements 30, thereby reducing the shading of the second conductive element 30 on the front of the battery main body structure 10 and ensuring the light utilization rate of the front of the battery main body structure 10.

[0039] It is worth noting that, regarding Figure 3 and Figure 6 The finger-intersecting structure of the first conductive region 11 and the second conductive region 12 shown has a relationship between the second conductive element 30 and the first conductive element 20 as follows: Figure 4 The structures shown are similar and will not be described in detail here.

[0040] Through the relationship between the second conductive element 30 and the first conductive element 20, it can be ensured that the second conductive element 30 and the first conductive element 20 cooperate with each other to avoid warping of the battery main body structure 10.

[0041] In this embodiment of the invention, in addition to the placement position of the second conductive element 30, it is also necessary to adjust the number of second conductive elements 30 and the corrective stress of the second conductive elements 30 so that the second conductive elements 30 can counteract the deformation caused by the first conductive element 20, thereby preventing warping of the back contact solar cell. The corrective stress of the second conductive element 30 generally refers to the corrective stress of a single second conductive element 30, which is generally related to the material and width of the second conductive element 30. Users can select the second conductive element 30 based on the calculated corrective stress.

[0042] More specifically, the number of second conductive elements 30 and the correction-related parameters of the second conductive elements 30 satisfy the following set of calculation formulas:

[0043] in, This indicates the number of second conductive elements 30 disposed on the front side of the battery main body structure 10; This indicates the safety factor of a single second conductive element 30; This represents the yield strength of a single second conductive element 30; This indicates the set correction factor; This indicates the number of first conductive elements 20 disposed on the back side of the battery main body structure 10; This represents the elastic modulus of the first conductive element 20; Indicates the coefficient of thermal expansion of the first conductive element 20; The coefficient of thermal expansion of the crystalline silicon substrate of the battery main structure 10 is indicated. Indicates the process temperature difference; This indicates the laying tension of the first conductive element 20; This represents the cross-sectional area of ​​the first conductive element 20; This indicates the laying stress of the second conductive element 30. By controlling the laying stress of the second conductive element 30 to be less than or equal to the yield strength of a single second conductive element 30 divided by a safety factor, it is ensured that the second conductive element 30 operates within its elastic deformation range and that no residual deformation remains after the second conductive element 30 is unloaded, thus ensuring long-term effective correction.

[0044] in, , , , , , and Both can be obtained through parameters provided by the selected conductive component (such as conductive wire or solder strip), or through testing the conductive component. Essentially, in the manufacturing process, in order to prevent the first conductive element 20 from bending and to ensure that the first conductive element 20 is in contact with the corresponding first conductive seed layer 112 or second conductive seed layer 122, an external tensile force is applied to the first conductive element 20. Essentially, in the manufacturing process, the maximum tensile force that can be applied to the second conductive component 30 externally is needed to prevent it from bending and breaking.

[0045] Optionally, the set correction factor The value range is 0.8 to 1.2. This correction factor is a set value. For example, the correction factor... It can be 0.8, 0.9, 1.0, 1.1 or 1.2, etc.

[0046] The safety factor of a single second conductive element 30 is a redundancy factor to avoid the degradation of mechanical properties due to fatigue and corrosion of the material. Its value typically ranges from 1.5 to 2, for example, 1.5, 1.7, 1.9, or 2. The yield strength of the second conductive element 30 refers to the yield limit when the second conductive element 30 yields, that is, the stress resisting slight plastic deformation, which is determined by the material of the second conductive element 30 itself. The elastic modulus and coefficient of thermal expansion of the first conductive element 20 are determined by the material of the first conductive element 20, and can be directly determined based on the selected first conductive element 20. The coefficient of thermal expansion of the crystalline silicon substrate 15 is directly determined based on the selected crystalline silicon substrate 15. The process temperature difference refers to the temperature rise of the battery main structure 10 during the welding process, generally the difference between the welding temperature and the ambient temperature.

[0047] The above calculation formulas can be used to reasonably control the number of the second conductive element 30 and select a more suitable second conductive element 30 according to the parameters related to correction, so as to better avoid the warping of the back contact solar cell through the cooperation between the second conductive element 30 and the first conductive element 20.

[0048] Furthermore, in embodiments of the present invention, such as Figure 4 (B) Figure 4 (C) Figure 4 (D) Figure 5 (B) Figure 5 (C) and Figure 5As shown in (D), both ends of the first conductive element 20 and both ends of the second conductive element 30 extend out of the battery body structure 10; the extension segment at one end of the first conductive element 20 is fixedly connected to the extension segment at one end of the corresponding second conductive element 30; the extension segment at the other end of the first conductive element 20 is fixedly connected to the extension segment at the other end of the corresponding second conductive element 30; by fixing the extension segment of the first conductive element 20 to the extension segment of the corresponding second conductive element 30, the effectiveness of the cooperation between the second conductive element 30 and the first conductive element 20 can be effectively improved. It should be noted that connecting the two ends of the first conductive element 20 to the two ends of the second conductive element 30 does not cause a short circuit. The second conductive element 30 is essentially an extension of the first conductive element 20. From the perspective of current transmission, the second conductive element 30 essentially increases the length of the first conductive element 20. The current collected by the first conductive element 20 is mainly transmitted through its adjacent back-contact solar cells or back-contact solar cell sheets connected in series. Even if some of the current collected by the first conductive element 20 enters the second conductive element 30, the current transmitted by the second conductive element 30 will still return to the first conductive element 20 and be transmitted through it. Although the fixed connection between the extensions of the two ends of the first conductive element 20 and the corresponding extensions of the second conductive element 30 will cause a slight increase in the resistance of the back-contact solar cell (i.e., the increase in the length of the second conductive element 30 is essentially an increase in the length of the first conductive element 20, and the increase in length causes a slight increase in resistance), its impact on the overall current transmitted by the back-contact solar cell is relatively small. Compared to the negative impact of a slight increase in resistance, the beneficial effect of the fixed connection between the extensions at both ends of the first conductive element 20 and the corresponding extensions of the second conductive element 30 (effectively preventing warping of the back contact solar cell and reducing the breakage rate of the back contact solar cell) can bring positive benefits to the back contact solar cell.

[0049] In an optional embodiment, the length of the extension segment at one end of the first conductive element 20 located on the first conductive region 11 is shorter than the length of the extension segment at one end of the first conductive element 20 located on the second conductive region 12, and the length of the extension segment at the other end of the first conductive element 20 located on the first conductive region 11 is longer than the length of the extension segment at the other end of the first conductive element 20 located on the second conductive region 12. This allows the extension segment at one end of the first conductive element 20 of the back-contact solar cell located on the first conductive region 11 to be directly welded to the extension segment at the other end of the first conductive element 20 of the second conductive region 12 of a back-contact solar cell adjacent to the extension segment at the other end. This facilitates the connection of back-contact solar cells in series to form a battery string.

[0050] In embodiments of the present invention, such as Figures 9 to 11 As shown, based on the battery main body structure 10 provided in any of the above embodiments, the front side of the battery main body structure 10 is provided with a plurality of grooves 13; a plurality of second conductive elements 30 are distributed in the plurality of grooves 13. Only one second conductive element 30 is provided in each groove 13. By providing grooves 13, on the one hand, it is convenient to position and install the second conductive elements 30; on the other hand, the reflected light from the second conductive elements 30 embedded in the grooves 13 can be reflected back to the front side of the battery main body structure 10, thereby ensuring light utilization.

[0051] In a preferred embodiment of the present invention, the second conductive element 30 is generally completely embedded in the groove 13 to ensure aesthetics while effectively improving the light utilization rate of the battery main structure 10. The height difference between the second conductive element 30 and the front surface of the battery main structure 10 refers to the height difference between the upper surface of the second conductive element 30 and the front surface of the crystalline silicon substrate 15.

[0052] In this embodiment of the invention, the depth of the groove 13 is 0.3mm to 0.7mm; the width of the groove 13 is 0.4mm to 1.2mm. For example, the depth of the groove 13 can be 0.3mm, 0.5mm, 0.6mm or 0.7mm, etc., and the width of the groove 13 can be 0.4mm, 0.5mm, 0.6mm, 0.8mm, 1mm or 1.2mm, etc. By limiting the depth and width of the groove 13, the groove 13 can be adapted to various types of second conductive components 30, ensuring industrialization.

[0053] Furthermore, the width of the second conductive element 30 is 0.1mm to 1.2mm; for example, the width of the second conductive element 30 can be 0.1mm, 0.3mm, 0.5mm, 0.8mm, 1mm or 1.2mm, etc. By controlling the width of the second conductive element 30, a reliable and stable connection can be formed between the second conductive element 30 and the front of the battery body structure 10.

[0054] In addition, the thickness of the second conductive component 30 is 0.3mm to 1mm. For example, the thickness of the second conductive component 30 can be 0.3mm, 0.5mm, 0.8mm or 1mm, etc., to ensure the reliability of the second conductive component 30 being welded and fixed to the front side of the battery main body structure 10 and to reduce the risk of breakage of the second conductive component 30.

[0055] In a preferred embodiment of the present invention, two of the plurality of second conductive elements 30 are disposed on the two side edge regions of the battery main body structure 10, so as to further improve the reliability of the cooperation between the second conductive element 30 and the first conductive element 20.

[0056] In a preferred embodiment of the present invention, the distance from the second conductive element 30 located in the edge region to the side it is close to is 1mm to 2mm. For example, this distance can be 1mm, 1.2mm, 1.5mm, 1.8mm or 2mm, etc. By adjusting this distance, the reliability of the fit between the second conductive element 30 and the first conductive element 20 can be further improved.

[0057] In a preferred embodiment, such as Figure 11 As shown, the cross-section of the second conductive element 30 is triangular, and optionally, the base of the triangle is 0.1mm to 1.2mm. For example, the base of the triangle can be 0.1mm, 0.5mm, or 1.2mm. By selecting a second conductive element 30 with a triangular cross-section, the sides of the triangle can reflect light onto the crystalline silicon substrate 15, thereby improving the light utilization rate of the back-contact solar cell. Furthermore, the cross-section of the second conductive element 30 can also be selected in other shapes, such as trapezoidal or rectangular, depending on the requirements.

[0058] Furthermore, embodiments of the present invention also provide a photovoltaic module. Specifically, the photovoltaic module may include: a backsheet, a lower encapsulating film, a cell array, an upper encapsulating film, and a cover plate stacked from bottom to top. The cell array includes multiple back-contact solar cells provided in any of the above embodiments, or back-contact cell sheets cut from back-contact solar cells provided in any of the above embodiments, connected in series and / or in parallel.

[0059] The battery array includes a series structure such as Figure 12 As shown, for two adjacent back-contact solar cells, the first conductive element 20 of the first conductive region 11 of one back-contact solar cell is connected to the first conductive element 20 of the second conductive region 12 of the other back-contact solar cell.

[0060] Furthermore, this embodiment of the invention also provides a method for fabricating a back-contact solar cell. Specifically, this method for fabricating a back-contact solar cell is used to fabricate the back-contact solar cell provided in any of the above embodiments. More specifically, the fabrication method may include: Step S1: Provide a battery body structure 10, wherein a first conductive region 11 and a second conductive region 12 are alternately arranged on the back side of the battery body structure 10 along a first direction D1, and adjacent first conductive regions 11 and second conductive regions 12 are electrically isolated from each other. Both the first conductive region 11 and the second conductive region 12 extend along a second direction D2, and the second direction D2 is perpendicular to the first direction D1.

[0061] The main battery structure 10 can be prepared by other processes or by this preparation method.

[0062] The battery main structure 10 provided in step S1 can be prepared using existing technology, that is, a first carrier collection layer 111 is formed on the back side of the crystalline silicon substrate 15 corresponding to the first conductive region 11, a second carrier collection layer 121 is formed on the back side of the crystalline silicon substrate 15 corresponding to the second conductive region 12, a conductive seed layer 112 or a first gate line is formed in the first conductive region 11, and a second conductive seed layer 122 or a second gate line is formed in the second conductive region 12. This will not be described in detail here.

[0063] Step S2: Lay a first conductive element 20 extending along the second direction D2 in each of the first conductive areas 11 and the second conductive areas 12, or lay a first conductive element 20 extending along the second direction D2 for connecting multiple first conductive areas 11 or multiple second conductive areas 12.

[0064] Step S3: A plurality of second conductive elements 30 are laid on the front side of the battery main body structure 10, and the extension direction of the plurality of second conductive elements 30 is consistent with the extension direction of the plurality of first conductive elements 20.

[0065] Step S4: Simultaneously weld the second conductive component 30 and the first conductive component 20.

[0066] Specifically, in step S4, the second conductive element 30 and the first conductive element 20 are simultaneously welded to the battery main structure 10 by heating and welding on a heating platform. More specifically, the second conductive element 30 and the first conductive element 20 are made of conductive wires coated with solder paste, and the conductive wires are connected to their corresponding positions by infrared welding.

[0067] The preparation method provided in this invention can simultaneously provide a second conductive element 30 and a first conductive element 20 on the front and back sides of a back-contact solar cell, respectively, to prevent the back-contact solar cell from warping. At the same time, it ensures that the back-contact solar cell can be completed through a simple process, which can be achieved by improving existing processes.

[0068] Furthermore, in cases where the preparation method provided in the embodiments of the present invention includes the preparation of the battery main structure 10, the above preparation method may further include steps S01 to S06 to prepare the battery main structure 10.

[0069] Step S01: Provide a crystalline silicon substrate 15. The back side of the crystalline silicon substrate 15 is provided with alternating first and second regions. Adjacent first and second regions are electrically isolated from each other. Both the first and second regions extend along a second direction D2, which is perpendicular to the first direction D1.

[0070] In this design, the first region on the back side of the crystalline silicon substrate 15 corresponds to the first conductive region 11, and the second region corresponds to the second conductive region 12. It should be noted that the first region and the second region generally do not overlap. In addition, a third region is provided between adjacent first and second regions. This third region can achieve electrical isolation between the first conductive region 11 and the second conductive region 12. This third region corresponds to the isolation region 16 between adjacent first conductive region 11 and second conductive region 12.

[0071] Step S02: Form a first carrier collection layer 111 on the back side of the crystalline silicon substrate 15.

[0072] Taking the first carrier collection layer 111 as an example of a tunneling oxide layer and a boron-doped polycrystalline silicon layer stacked from the inside to the outside, the tunneling oxide layer is first deposited by a thermal oxidation process, and then the boron-doped polycrystalline silicon layer is deposited on the outside of the tunneling oxide layer by a process such as plasma chemical vapor deposition. Understandably, during this process, a borosilicate glass layer can be formed on the outside of the boron-doped polycrystalline silicon layer, and a first wrap-around coating corresponding to the tunneling oxide layer, a second wrap-around coating corresponding to the boron-doped polycrystalline silicon layer, and a third wrap-around coating corresponding to the borosilicate glass layer are stacked from the inside to the outside on the front side of the crystalline silicon substrate 15.

[0073] Step S03: Remove the first carrier collection layer 111 corresponding to the second region.

[0074] Specifically, this step can first use a laser to remove the borosilicate glass layer and the third wrap-around coating corresponding to the second region, then use an alkaline solution to clean and remove the boron-doped polysilicon layer, tunneling oxide layer, second wrap-around coating, and first wrap-around coating corresponding to the second region, and then texturing the second region and the front side of the crystalline silicon substrate to form a textured structure. In addition, in this step, the first carrier collection layer 111 of the isolation region 16 can be removed simultaneously.

[0075] Step S04: A second carrier collection layer 121 is formed on the back side of the crystalline silicon substrate 15, corresponding to the second region and outside the first carrier collection layer 111.

[0076] In addition, step S04 can also form a second carrier collection layer 121 in the third region corresponding to the isolation region 16.

[0077] Taking the second carrier collection layer 121 as an example of a tunneling oxide layer and a phosphorus-doped polycrystalline silicon layer stacked from the inside to the outside, the tunneling oxide layer is first deposited by thermal oxidation process, and then the phosphorus-doped polycrystalline silicon layer is deposited on the outside of the tunneling oxide layer by processes such as plasma chemical vapor deposition. It can be understood that during this step, a phosphorus-silicon glass layer can be formed on the outside of the phosphorus-doped polycrystalline silicon layer, and a fourth wrap-around coating layer corresponding to the tunneling oxide layer, a fifth wrap-around coating layer corresponding to the phosphorus-doped polycrystalline silicon layer, and a sixth wrap-around coating layer corresponding to the phosphorus-silicon glass layer are stacked from the inside to the outside on the front side of the crystalline silicon substrate 15.

[0078] Step S05: Remove the second carrier collection layer 121 on the back side of the crystalline silicon substrate 15 corresponding to the first region, and use a laser to etch a plurality of grooves 13 on the front side of the crystalline silicon substrate 15.

[0079] In addition, step S05 can simultaneously remove the second carrier collection layer 121 corresponding to the third region of the isolation region 16 while removing the second carrier collection layer 121 corresponding to the first region.

[0080] Specifically, the phosphorus silicate glass layer and the fourth surrounding plating layer corresponding to the first and third regions are first removed by laser processing. Then, the phosphorus-doped polysilicon layer and the fifth surrounding plating layer corresponding to the first and third regions are removed by alkaline etching. Next, the tunneling oxide layer and borosilicate glass layer corresponding to the outer sides of the first and third regions are removed by HF solution cleaning, and the fourth surrounding plating layer and the remaining phosphorus silicate glass layer in the second region are removed. Afterward, multiple grooves 13 are formed on the front side of the silicon substrate 15 by laser etching. In addition, the second carrier collection layer 121 corresponding to the isolation region 16 can also be removed simultaneously in this step.

[0081] Optionally, in step S05, the laser wavelength for forming the groove 13 is 355nm or 532nm, the frequency is 150kHz to 600kHz, the etching rate is 15m / s to 40m / s, and the laser power is 4W to 40W. For example, the laser frequency for forming the groove 13 can be 150kHz, 200kHz, 400kHz, 500kHz, or 600kHz, etc., the etching rate can be 15m / s, 20m / s, 25m / s, 30m / s, 35m / s, or 40m / s, etc., and the laser power can be 4W, 5W, 10W, 15W, 20W, 30W, 35W, or 40W, etc. By controlling the laser parameters, laser damage can be effectively reduced.

[0082] Step S06: A first conductive seed layer 112 or a first gate line is formed outside the first carrier collection layer 111 in the first region, and a second conductive seed layer 122 or a second gate line is formed outside the second carrier collection layer 121 in the second region.

[0083] Understandably, the first region of the crystalline silicon substrate 15, the first carrier collection layer 111, and the first conductive seed layer 112 or the first gate line constitute the first conductive region 11 or the main part of the first conductive region 11 of the battery main structure 10, and the second region of the crystalline silicon substrate 15, the second carrier collection layer 121, and the second conductive seed layer 122 or the second gate line constitute the second conductive region 12 or the main part of the second conductive region 12 of the battery main structure 10.

[0084] Furthermore, based on the above steps S01 to S06, the specific implementation of the above step S3 may include: laying multiple second conductive elements 30 in multiple grooves 13.

[0085] The technical solution provided by the embodiments of the present invention will be described in detail below with reference to an example and a comparative example.

[0086] Example: Step A1: Perform pre-cleaning, texturing, and polishing treatments on the N-type crystalline silicon substrate in sequence.

[0087] Step A2: A tunneling oxide layer and an intrinsic polysilicon layer are sequentially stacked on the back side of the N-type crystalline silicon substrate, and boron diffusion is performed on the intrinsic polysilicon layer to obtain a boron-doped polysilicon layer (P+poly layer) and a borosilicate glass layer (BSG layer) outside the P+poly layer.

[0088] Step A3: Laser grooving is performed on the N-type conductive region and isolation region on the back side of the N-type crystalline silicon substrate, and the laser area is polished to form a tunneling oxide layer, a P+poly layer and a BSG layer stacked from the inside to the outside of the P-type conductive region.

[0089] Step A4: A tunneling oxide layer and an intrinsic polysilicon layer are stacked from the inside to the outside in the exposed area on the back side of the N-type crystalline silicon substrate and the P-type conductive area. Phosphorus diffusion is then performed on the intrinsic polysilicon layer to obtain a phosphorus-doped polysilicon layer (N+poly layer) and a phosphorus silicon glass layer (PSG layer).

[0090] Step A5: Use a laser to remove the PSG layer corresponding to the P-type conductive region and the isolation region.

[0091] Step A6: Using a laser with a wavelength of 355nm, at a frequency of 300 kHz, a speed of 30m / s, and a laser power of 20W, etch grooves at specific positions on the front side of the N-type crystalline silicon substrate.

[0092] Step A7: Use an alkaline solution to clean and remove the N+poly layer corresponding to the P-type conductive region and the isolation region, and use an HF solution to clean and remove the tunneling oxide layer outside the P-type conductive region and the remaining PSG layer in the N-type conductive region and the isolation region.

[0093] Step A8: Prepare a textured structure on the isolation region on the back side of the N-type crystalline silicon substrate and on the front side of the N-type crystalline silicon substrate to obtain a solar cell.

[0094] Step A9: Double-sided coating of the battery cells to generate a passivation layer.

[0095] Step A10: Print conductive seed layers on the N-type conductive area and P-type conductive area on the back of the solar cell, and sinter them.

[0096] Step A11: Arrange the battery cells, wherein the conductive areas of each pair of adjacent battery cells with opposite conductivity types correspond to each other. Conductive wires (i.e., the first conductive element in the above embodiment) are laid through the conductive seeds of each battery cell, and solder ribbons (i.e., the second conductive element in the above embodiment) are placed in the grooves on the front side of the battery cell. The conductive wires are bonded to the conductive seed layer by heating and welding, and the solder ribbons are fixed in the grooves on the front side of the battery cell.

[0097] Step A12: The extensions of the conductive wires extending from both ends of the battery cell are fixedly connected to the corresponding extensions of the welding strips by laser welding heating.

[0098] Step A13: Use a laser to break some of the conductive wires between adjacent solar cells, so that the adjacent solar cells are connected in series.

[0099] Comparative Example

[0100] The difference from the embodiment is that steps A6 and A11 are omitted.

[0101] The warpage of the examples and comparative examples was tested separately. Warpage is defined as the maximum vertical distance difference between any two points on the solar cell and the "ideal reference plane" (i.e., the height difference between the highest and lowest points), which reflects the overall curvature of the solar cell. The warpage was measured using a probe profilometer. The test results for the examples and comparative examples are shown in Table 1.

[0102] Table 1

[0103] As can be seen from the test results in Table 1, the warpage of the solar cell in the embodiment is 1.5 mm, while the warpage of the solar cell in the comparative example is as high as 4 mm. Therefore, it can be concluded that the warpage of the back-contact solar cell provided in this embodiment of the invention is effectively improved.

[0104] The above steps are provided only to help understand the method, structure, and core ideas of this invention. Those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A back-contact solar cell, characterized in that, include: The battery body structure (10) has a first conductive region (11) and a second conductive region (12) of opposite conductivity types arranged alternately on the back side of the battery body structure (10) along a first direction (D1). The adjacent first conductive region (11) and second conductive region (12) are electrically isolated. The first conductive region (11) and the second conductive region (12) both extend along a second direction (D2), which is perpendicular to the first direction (D1). A plurality of first conductive elements (20), wherein the plurality of first conductive elements (20) are respectively disposed in the first conductive region (11) and the second conductive region (12) and extend along the second direction (D2), or, each of the first conductive elements (20) extends along the first direction (D1) and connects to the plurality of first conductive regions (11) or the plurality of second conductive regions (12); and, A plurality of second conductive elements (30) are disposed on the front side of the battery body structure (10), wherein the extension direction of the plurality of second conductive elements (30) is consistent with the extension direction of the plurality of first conductive elements (20).

2. The back-contact solar cell according to claim 1, characterized in that, In the thickness direction of the battery body structure (10), each of the second conductive elements (30) corresponds to one of the first conductive elements (20), and each of the second conductive elements (30) corresponds to a different first conductive element (20).

3. The back-contact solar cell according to claim 2, characterized in that, Both ends of the first conductive element (20) and both ends of the second conductive element (30) extend out of the battery body structure (10). One end of the first conductive element (20) is fixedly connected to one end of the corresponding second conductive element (30); the other end of the first conductive element (20) is fixedly connected to the other end of the corresponding second conductive element (30). Optionally, the length of the extension segment at one end of the first conductive element (20) located on the first conductive region (11) is less than the length of the extension segment at one end of the first conductive element (20) located on the second conductive region (12), and the length of the extension segment at the other end of the first conductive element (20) located on the first conductive region (11) is greater than the length of the extension segment at the other end of the first conductive element (20) located on the second conductive region (12).

4. The back-contact solar cell according to any one of claims 1 to 3, characterized in that, The front side of the battery body structure (10) is provided with multiple grooves (13). Multiple second conductive elements (30) are distributed within multiple grooves (13); Optionally, the depth of the groove (13) is 0.3mm to 0.7mm; the width of the groove (13) is 0.4mm to 1.2mm; Optionally, the width of the second conductive element (30) is 0.1 mm to 1.2 mm; Optionally, the thickness of the second conductive element (30) is 0.3 mm to 1 mm.

5. The back-contact solar cell according to claim 1, characterized in that, The number of the second conductive element (30) and the correction-related parameters of the second conductive element (30) satisfy the following set of calculation formulas: in, This indicates the number of the second conductive elements (30) disposed on the front side of the battery main body structure (10); This indicates the safety factor for a single second conductive element (30); This represents the yield strength of a single second conductive element (30); This indicates the set correction factor; This indicates the number of the first conductive elements (20) disposed on the back side of the battery main body structure (10); This represents the elastic modulus of the first conductive element (20); The coefficient of thermal expansion of the first conductive element (20) is indicated; The coefficient of thermal expansion of the crystalline silicon substrate of the main battery structure (10) is indicated; Indicates the process temperature difference; This indicates the laying tension of the first conductive element (20); This represents the cross-sectional area of ​​the first conductive element (20); This indicates the laying stress of the second conductive element (30); Optionally, the set correction factor The value range is 0.8 to 1.

2.

6. The back-contact solar cell according to any one of claims 1 to 3 and 5, characterized in that, Two of the plurality of second conductive elements (30) are respectively disposed on the two side edge regions of the battery body structure (10); Optionally, the distance from the second conductive element (30) located in the edge region to the side it is close to is 1 mm to 2 mm.

7. The back-contact solar cell according to any one of claims 1 to 3 and 5, characterized in that, The battery main structure (10) includes: a first carrier collection layer (111) disposed on the first conductive region (11) and a first conductive seed layer (112) or a first grid line disposed outside the first carrier collection layer (111); a second carrier collection layer (121) disposed on the second conductive region (12) and a second conductive seed layer (122) or a second grid line disposed outside the second carrier collection layer (121); The first conductive element (20) disposed in the first conductive region (11) is electrically connected to the first conductive seed layer (112) or the first gate line of the first conductive region (11). The second conductive element (30) disposed in the second conductive region (12) is electrically connected to the second conductive seed layer (122) or the second gate line of the second conductive region (12); Optionally, the first conductive seed layer (112) or the first gate line extends along the second direction (D2); the second conductive seed layer (122) or the second gate line extends along the second direction (D2); or, the first conductive region (11) and the second conductive region (12) are arranged in an interdigitated manner, and a first conductive seed layer (112) or a first gate line extending along the first direction (D1) is arranged along the second direction (D2) on each first conductive region (11), and a second conductive seed layer (122) or a second gate line extending along the first direction (D1) is arranged along the second direction (D2) on each second conductive region (12), and the first conductive element (20) on each first conductive region (11) is connected in series with the first conductive seed layer (112) or the first gate line arranged along the second direction on the first conductive region (11); the first conductive element (20) on each second conductive region (12) is connected in series with the second conductive seed layer (122) or the second gate line arranged along the second direction on the second conductive region (12). Optionally, the cross-section of the second conductive element (30) is triangular, and the base of the triangle is 0.1mm to 1.2mm. Optionally, the battery body structure (10) further includes a passivation antireflection layer (14) disposed on the front side of the battery body structure (10), and the second conductive element (30) is disposed above or below the passivation antireflection layer (14).

8. A photovoltaic module, characterized in that, include: The layers stacked from bottom to top are: backsheet, lower encapsulating film, battery array, upper encapsulating film, and cover plate. The battery array includes multiple back-contact solar cells as described in any one of claims 1 to 7, or back-contact cell sheets cut from the back-contact solar cells as described in any one of claims 1 to 7, connected in series and / or in parallel.

9. A method for fabricating a back-contact solar cell, characterized in that, include: Step S1: Provide a battery body structure (10), wherein a first conductive region (11) and a second conductive region (12) are alternately arranged on the back side of the battery body structure (10) along a first direction (D1), adjacent first conductive regions (11) and second conductive regions (12) are electrically isolated, and the first conductive region (11) and the second conductive region (12) both extend along a second direction (D2), and the second direction (D2) is perpendicular to the first direction (D2). Step S2: Lay a first conductive element (20) extending along the second direction (D2) in each of the first conductive areas (11) and the second conductive areas (12), or lay a first conductive element (20) extending along the first direction (D1) and used to connect multiple first conductive areas (11) or multiple second conductive areas (12). Step S3: A plurality of second conductive elements (30) are laid on the front side of the battery main body structure (10), and the extension direction of the plurality of second conductive elements (30) is consistent with the extension direction of the plurality of first conductive elements (20). Step S4: Simultaneously weld the second conductive element (30) and the first conductive element (20).

10. The preparation method according to claim 9, characterized in that, Also includes: The battery main body structure (10) or a part of the battery main body structure (10) is obtained through the following steps S01 to S06: Step S01: Provide a crystalline silicon substrate (15), wherein the back side of the crystalline silicon substrate (15) is provided with an alternating first region and a second region, both the first region and the second region extending along a second direction (D2), the second direction (D2) being perpendicular to the first direction (D1). Step S02: A first carrier collection layer (111) is formed on the back side of the crystalline silicon substrate (15). Step S03: Remove the first carrier collection layer (111) corresponding to the second region. Step S04: A second carrier collection layer (121) is formed on the back side of the crystalline silicon substrate (15) corresponding to the second region and the outside of the first carrier collection layer (111). Step S05: Remove the second carrier collection layer (121) on the back side of the crystalline silicon substrate (15) corresponding to the first region, and use a laser to etch a plurality of grooves (13) on the front side of the crystalline silicon substrate (15). Step S06: A first conductive seed layer (112) or a first gate line is formed outside the first carrier collection layer (111) in the first region, and a second conductive seed layer (122) or a second gate line is formed outside the second carrier collection layer (121) in the second region. Step S3 includes: laying a plurality of the second conductive elements (30) in the plurality of grooves (13); Optionally, in step S05, the laser wavelength for forming the groove (13) is 355nm or 532nm, the frequency is 150KHz~600KHz, the etching rate is 15m / s~40m / s, and the laser power is 4W~40W.

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