Back contact battery, battery assembly and photovoltaic system

Abstract

The invention is applicable to the field of photovoltaic technology, and provides a back contact battery, a battery assembly and a photovoltaic system. The first doping parts and the second doping parts are arranged on the back surface of the silicon wafer and extend in the first direction, and the first doping parts and the second doping parts are alternately arranged at intervals in the second direction; the third doping part is arranged on the back surface and extends along the second direction, and the third doping part is connected with the first doping part; the identification doping part is arranged between the second doping part and the third doping part; a first contact hole is formed in the position, corresponding to the first doping part, of the passivation layer, a second contact hole is formed in the position, corresponding to the second doping part, of the passivation layer, and the center line, in the first direction, of the identification doping part and the center line, in the first direction, of the corresponding second contact hole are collinear. According to the back contact cell, the printing precision of the mask can be improved, and the good current collection effect of the fine grid is achieved.

Description

Technical Field

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

[0002] A solar cell is a semiconductor device that converts solar energy into electrical energy. Under sunlight, a solar cell generates a photocurrent, which is then output as electrical energy through electrodes. In recent years, solar cell manufacturing technology has continuously improved, production costs have decreased, and conversion efficiency has increased. Solar cell power generation has become increasingly widespread and is an important energy source for electricity supply. In particular, because the positive and negative electrodes of a back-contact solar cell are designed on the back of the cell, the front of the cell is not obstructed, which significantly improves the cell's conversion efficiency.

[0003] In related technologies, when fabricating fine grids for back-contact solar cells using electroplating, a passivation layer is typically first prepared on the entire back side of the silicon wafer. Contact holes are then created at the locations where the fine grids need to be placed on the passivation layer. After electroplating a full-surface metal layer on the back side, a patterned mask corresponding to the fine grid pattern is printed onto this metal layer. The metal layer not covered by the mask is then removed, and finally, the mask is removed as well, leaving the patterned fine grids. Since the width and position of the fine grids are determined by the mask, good alignment between the mask and the corresponding contact holes is required to ensure good contact between the fine grids and the corresponding contact holes. However, during the manufacturing process of back-contact solar cells, after printing the mask, it completely covers the contact holes on the passivation layer. Since there is usually no corresponding alignment reference on the back side of the solar cell, it is difficult to determine whether the center line of the mask and the center line of the contact holes are collinear. This makes it difficult to ensure that the center line of the fine grid and the center line of the contact holes are collinear, resulting in low alignment accuracy between the fine grid and the contact holes. This can easily lead to misalignment of the fine grid relative to the contact holes, affecting the current collection effect of the fine grid and consequently the power generation efficiency of the cell. Summary of the Invention

[0004] This invention provides a back-contact battery, which aims to solve the problem that existing back-contact batteries have low alignment accuracy between the fine grid and the contact hole, and the fine grid is prone to misalignment relative to the contact hole, thereby affecting the current collection effect of the fine grid and thus affecting the power generation efficiency of the battery.

[0005] This invention is implemented by providing a back contact battery, comprising: Silicon wafers; A first doped portion and a second doped portion with opposite doping types are disposed on the back side of the silicon wafer. The first doped portion and the second doped portion are both extended along a first direction. The first doped portion and the second doped portion are alternately spaced along a second direction, and the second direction intersects the first direction. A third doped portion is provided on the back side and has the same doping type as the first doped portion. The third doped portion extends along the second direction and is connected to the first doped portion. An isolation region is provided between the first doped portion and the second doped portion, and between the second doped portion and the third doped portion. An identification doping portion is provided between the second doping portion and the third doping portion; A passivation layer covers the first doped portion, the second doped portion, the third doped portion, the marking doped portion, and the isolation region. The passivation layer has a first contact hole for setting a first fine gate at the position corresponding to the first doped portion, and a second contact hole for setting a second fine gate at the position corresponding to the second doped portion. The marking doped portion and the corresponding second contact hole are opposite each other along the first direction, and the center line of the marking doped portion along the first direction is collinear with the center line of the corresponding second contact hole along the first direction.

[0006] Preferably, the identification doped portion is connected to at least one of the second doped portion and the third doped portion.

[0007] Preferably, the marking doping portion is connected to both the second doping portion and the third doping portion.

[0008] Preferably, the passivation layer includes a marking portion covering the marking doped portion, wherein the center line of the marking portion along the first direction is collinear with the center line of the marking doped portion along the first direction.

[0009] Preferred, including: A plurality of first fine gates are provided, each of the first fine gates being disposed on a corresponding first contact hole, the first fine gate passing through the corresponding first contact hole and contacting the first doped portion.

[0010] Preferred options also include: A plurality of second fine gates are provided, each second fine gate being disposed on a corresponding second contact hole, the second fine gate passing through the corresponding second contact hole and contacting the second doped portion.

[0011] Preferably, the number of the marking doped portions is at least two, and at least two of the marking doped portions are located at diagonal positions on the silicon wafer.

[0012] Preferably, the number of the marking doped portions is at least four, and the marking doped portions are provided at least at the four corners of the silicon wafer.

[0013] Preferably, the marking doping portion and the third doping portion have the same doping type, and the marking doping portion and the third doping portion are integrally formed.

[0014] Preferably, the marking doped portion and the second doped portion have the same doping type, and the marking doped portion and the second doped portion are integrally formed.

[0015] Preferably, one end of the marking doped portion is connected to the third doped portion, and the other end is stacked on top of the second doped portion.

[0016] Preferably, one end of the marking doped portion is connected to the second doped portion, and the other end is stacked on top of the third doped portion.

[0017] Preferably, the size of the doped marking portion along the first direction is 100 micrometers to 180 micrometers.

[0018] Preferably, the size of the marking doped portion along the second direction is 100 micrometers to 180 micrometers.

[0019] Preferably, the first doped portion, the identification doped portion, and the third doped portion are all N-type doped portions, and the second doped portion is a P-type doped portion.

[0020] Preferred options also include: A first main gate is disposed on the third doped portion, the first main gate is connected to at least a portion of the first fine gates, and the second fine gates are intermittently disposed at the location of the first main gate.

[0021] Preferred options also include: A fourth doped portion is provided on the back side, the fourth doped portion extends along the second direction, the fourth doped portion and the second doped portion have the same doping type, the fourth doped portion is connected to the second doped portion, and the fourth doped portion and the third doped portion are alternately spaced along the first direction; A second main gate is disposed on the fourth doped portion, the second main gate is connected to at least a portion of the second fine gates, and the first fine gates are intermittently disposed at the location of the second main gate.

[0022] Preferably, the silicon wafer includes a first edge and a second edge disposed opposite to each other along the second direction, and the first main gate and the second main gate are disposed on the back side near the first edge and the second edge, respectively. The first main gate near the first edge is spaced apart from the first main gate near the second edge, and the second main gate near the first edge is spaced apart from the second main gate near the second edge.

[0023] Preferably, the ratio of the dimension of the first main gate along the second direction to the dimension of the silicon wafer along the second direction is 0.05 to 0.1; and / or, the ratio of the dimension of the second main gate along the second direction to the dimension of the silicon wafer along the second direction is 0.05 to 0.1.

[0024] The present invention also provides a battery assembly including the aforementioned back contact battery.

[0025] The present invention also provides a photovoltaic system including the above-described battery module.

[0026] The present invention provides a back contact battery having at least one marking doped portion, the marking doped portion being disposed between a second doped portion and a third doped portion, a first contact hole being formed in the passivation layer corresponding to the position of the first doped portion, a second contact hole being formed in the passivation layer corresponding to the position of the second doped portion, and the center line of the marking doped portion along the first direction being collinear with the center line of the corresponding second contact hole along the first direction. Because the marking doped portion is set between the second doped portion and the third doped portion, the marking doped portion will be raised relative to the surrounding isolation area. Therefore, after the passivation layer is prepared on the back side of the silicon wafer and the metal layer is formed by electroplating the entire back side, the passivation layer and the metal layer will also be raised relative to the surrounding area at the marking doped portion position. That is, after the metal layer is formed by electroplating the entire back side, the metal layer will form a raised structure at the marking doped portion position that is raised relative to the surrounding area. Since the center line of the raised structure of the metal layer along the first direction is collinear with the center line of the marking doped portion along the first direction, and the center line of the marking doped portion along the first direction is collinear with the center of the corresponding second contact hole in the first direction, when the center line of the printed mask in the first direction is collinear with the center line of the raised structure of the back metal layer in the first direction, it is considered that the center line of the mask is collinear with the center line of the corresponding second contact hole. Therefore, by setting the marking doped portion, the present invention facilitates the formation of a corresponding raised structure in the back metal layer as a reference for mask alignment.

[0027] During mask printing, when the centerline of the mask near the protruding structure of the metal layer along the first direction is collinear with the centerline of the protruding structure of the metal layer along the first direction, the centerline of the second fine grid and the centerline of the second contact hole can be ensured to be collinear. Conversely, when the centerline of the mask near the protruding structure of the metal layer along the first direction is not collinear with the centerline of the protruding structure of the metal layer along the first direction, the mask is first removed, and then the printing screen is moved a corresponding distance along the second direction according to the offset direction of the centerline of the mask relative to the centerline of the protruding structure of the metal layer, until the centerline of the mask along the first direction is collinear with the centerline of the protruding structure of the metal layer along the first direction, ensuring the printed mask... The centerline of the film is collinear with the centerline of the corresponding second contact hole in the first direction, thereby improving the printing accuracy of the mask. This ensures that the centerline of the second fine grid is collinear with the centerline of the second contact hole, which in turn ensures that the centerline of the first fine grid is collinear with the centerline of the first contact hole in the first direction. This improves the alignment accuracy of the second fine grid with the second contact hole and the first fine grid with the first contact hole, preventing the second fine grid from shifting relative to the second contact hole and the first fine grid from shifting relative to the first contact hole. This ensures reliable contact between the second fine grid and the second doped part and between the first fine grid and the first doped part, achieving good current collection for both the second and first fine grids and ensuring good power generation efficiency of the battery. Attached Figure Description

[0028] Figure 1 A schematic diagram of the back side of a back-contact battery provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a partial structure of a back contact battery provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of another part of the structure of a back contact battery provided in an embodiment of the present invention; Figure 4 for Figure 3 A magnified view of part A in the middle; Figure 5 This is a partial schematic diagram of a back contact battery after a passivation layer has been applied, according to an embodiment of the present invention. Figure 6 This is a partial cross-sectional schematic diagram of a back contact battery with the first and second fine grids removed, provided as an embodiment of the present invention. Figure 7 This is a partial cross-sectional schematic diagram of a back contact battery with a first fine grid and a second fine grid provided in an embodiment of the present invention; Figure 8 This is a partial scanning electron microscope image of a back contact battery without a passivation layer, provided in an embodiment of the present invention. Figure 9 This is a partial scanning electron microscope image of a back contact battery after printing a mask, provided as an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the invention, and should not be construed as limiting the invention. Furthermore, it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0030] In the description of this invention, it should be understood that the terms "upper", "lower", "backlight", "front", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this invention 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, and therefore should not be construed as a limitation of this invention.

[0031] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0032] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0033] Please refer to Figures 1-7 This invention provides a back contact battery 100, comprising: Silicon wafer 1; A first doped portion 2 and a second doped portion 3 are disposed on the back side 11 of the silicon wafer 1. The doping types of the first doped portion 2 and the second doped portion 3 are opposite. Both the first doped portion 2 and the second doped portion 3 extend along the first direction X. The first doped portion 2 and the second doped portion 3 are alternately arranged along the second direction Y. The second direction Y intersects the first direction X. A third doped portion 4 is provided on the back side 11. The third doped portion 4 extends along the second direction Y. The third doped portion 4 and the first doped portion 2 have the same doping type. The third doped portion 4 is connected to the first doped portion 2. An isolation region 112 is provided between the first doped portion 2 and the second doped portion 3 and between the second doped portion 3 and the third doped portion 4. At least one identification doping part 6 is provided between the second doping part 3 and the third doping part 4; Passivation layer 7 covers the first doped portion 2, the second doped portion 3, the third doped portion 4, the marking doped portion 6, and the isolation region 112. The passivation layer 7 has a first contact hole 71 for setting the first fine gate 8 at the position corresponding to the first doped portion 2, and a second contact hole 72 for setting the second fine gate 9 at the position corresponding to the second doped portion 3. The marking doped portion 6 and the corresponding second contact hole 72 are opposite each other along the first direction X, and the center line of the marking doped portion 6 along the first direction X is collinear with the center line of the corresponding second contact hole 72 along the first direction X.

[0034] In this embodiment of the invention, the back side 11 of the silicon wafer 1 is the side facing away from sunlight when the back contact battery 100 is working. There are multiple first doped portions 2 and multiple second doped portions 3, and these multiple first doped portions 2 and multiple second doped portions 3 are alternately arranged along a second direction Y. The second direction Y may be perpendicular to the first direction X, or it may not be perpendicular to it. Preferably, the second direction Y is perpendicular to the first direction X.

[0035] In this embodiment, the first doped portion 2 and the second doped portion 3 are either P-type or N-type doped. Specifically, the first doped portion 2 can be P-type and the second doped portion 3 can be N-type; or, if the first doped portion 2 is N-type, the second doped portion 3 can be P-type. The P-type doped portion is doped with a P-type dopant, and the N-type doped portion is doped with an N-type dopant. The P-type dopant is a dopant of a Group IIIA element in the periodic table, and the N-type dopant is a dopant of a Group VA element in the periodic table. For example, the P-type dopant can be a boron dopant, and the N-type dopant can be a phosphorus dopant. The first doped portion 2, the second doped portion 3, the third doped portion 4, and the marker doped portion 6 are specifically a stack of one or more of the following: a polycrystalline silicon layer, an amorphous silicon layer, and a microcrystalline silicon layer.

[0036] In this embodiment of the invention, the third doped portion 4 extends along the second direction Y, that is, the third doped portion 4 intersects with the first doped portion 2. Preferably, the third doped portion 4 is perpendicular to the first doped portion 2. The third doped portion 4 and the first doped portion 2 have the same doping type, and the third doped portion 4 is connected to the first doped portion 2 to achieve electrical connection between the third doped portion 4 and the first doped portion 2. Specifically, the isolation region 112 is a trench.

[0037] In this embodiment of the invention, the marking doped portion 6 can be connected to at least one of the second doped portion 3 and the third doped portion 4, or the marking doped portion 6 can be simultaneously spaced apart from both the second doped portion 3 and the third doped portion 4. Preferably, the marking doped portion 6 being connected to at least one of the second doped portion 3 and the third doped portion 4 can be configured such that the marking doped portion 6 is connected to the second doped portion 3 but spaced apart from the third doped portion 4, facilitating the simultaneous fabrication of the marking doped portion 6 and the second doped portion 3; or the marking doped portion 6 is connected to the third doped portion 4 but spaced apart from the second doped portion 3, facilitating the simultaneous fabrication of the marking doped portion 6 and the third doped portion 4; or the marking doped portion 6 is simultaneously connected to both the second doped portion 3 and the third doped portion 4. Figures 2-5 The illustration only shows the case where the doped part 6 is connected to both the second doped part 3 and the third doped part 4.

[0038] An embodiment of the present invention provides a back contact battery 100 by providing at least one marking doped portion 6, which is disposed between a second doped portion 3 and a third doped portion 4. A passivation layer 7 has a first contact hole 71 for setting a first fine grid 8 at a position corresponding to the first doped portion 2, and a second contact hole 72 for setting a second fine grid 9 at a position corresponding to the second doped portion 3. The marking doped portion 6 and the corresponding second contact hole 72 are opposite to each other along a first direction X. Specifically, the second contact hole 72 corresponding to the marking doped portion 6 is a second contact hole 72 disposed opposite to the marking doped portion 6 along the first direction X, that is, the second contact hole 72 closest to the marking doped portion 6 along the first direction X. The centerline of the doped marking portion 6 along the first direction X is collinear with the centerline of the corresponding second contact hole 72 along the first direction X. This can be understood as the orthographic projection of the centerline of the doped marking portion 6 along the first direction X onto the silicon wafer 1 coincides with the orthographic projection of the centerline of the corresponding second contact hole 72 along the first direction X onto the silicon wafer 1. In other words, the orthographic projections of the centerlines of the doped marking portion 6 and the corresponding second contact hole 72 along the first direction X onto the silicon wafer 1 are both located on a central axis L set along the first direction X. That is, the doped marking portion 6 is symmetrically arranged about the central axis L, and the corresponding second contact hole 72 is also symmetrically arranged about the central axis L. Alternatively, it can be understood that the center of the doped marking portion 6 and the center of the corresponding second contact hole 72 are collinear in the first direction X. Specifically, the center of the second contact hole 72 is the center of its largest circumscribed circle, and the center of the doped marking portion 6 is the center of its largest circumscribed circle.

[0039] Please refer to the reference. Figures 8-9 In this embodiment of the invention, by providing a marking doped portion 6 between the second doped portion 3 and the third doped portion 4, since the isolation region 112 is a region that has been laser-etched, while the marking doped portion 6 is a region that has not been laser-etched, the marking doped portion 6 will be raised relative to the surrounding isolation region 112. Therefore, after the passivation layer 7 is prepared on the back side 11 of the silicon wafer 1 and the metal layer 18 is formed by electroplating the entire back side 11, the passivation layer 7 and the metal layer 18 will also be raised relative to the surrounding area at the location of the marking doped portion 6. That is, after the entire metal layer 18 is electroplated to form, the metal layer 18 will form a raised structure 181 at the location of the marking doped portion 6 that is raised relative to the surrounding area (e.g., Figure 9(As shown). Since the protrusion structure 181 of the metal layer 18 is aligned with the position of the marking doped portion 6, and the center line of the marking doped portion 6 along the first direction X is collinear with the center line of the corresponding second contact hole 72 along the first direction X, after printing the mask 19, when the center line of the mask 19 closest to the protrusion structure 181 of the metal layer 18 along the first direction X is collinear with the center line of the protrusion structure 181 of the metal layer 18, it is considered that the center line of the mask 19 along the first direction X is collinear with the center line of the corresponding second contact hole 72 along the first direction X. Therefore, by setting the marking doped portion 6, the present invention can... After the metal layer 18 is formed on the entire back side 11, a raised structure 181 is formed on the metal layer 18 at the position corresponding to the doped part 6. The raised structure 181 contrasts with the surrounding area. The raised structure 181 serves as a reference for adjusting the offset during the printing of the mask 19, which facilitates the accurate alignment of the mask 19 with the second contact hole 72 and can improve the printing accuracy of the mask 19. This ensures that the center line of the second fine gate 9 in the first direction X is collinear with the center line of the second contact hole 72 in the first direction X, and simultaneously ensures that the center line of the first fine gate 8 in the first direction X is collinear with the center line of the first contact hole 71 in the first direction X.

[0040] Specifically, after printing the mask 19, when the center line of the mask 19 closest to the protrusion 181 of the metal layer 18 along the first direction X is collinear with the center line of the protrusion 181 of the metal layer 18 along the first direction X, it can be considered that the center line of the second contact hole 72 is collinear with the center line of the mask 19 in the first direction X, thus simultaneously ensuring that the center line of the second fine grid 9 is collinear with the center line of the second contact hole 72. Conversely, when the center line of the mask 19 closest to the protrusion 181 of the metal layer 18 is not collinear with the center line of the protrusion 181 of the back metal layer 18, it is necessary to first remove the mask 19, and according to the offset direction of the center line of the printed mask 19 relative to the center line of the protrusion 181, move the screen of the printed mask 19 along the second direction Y by a corresponding distance until the center line of the printed mask 19 is collinear with the center line of the protrusion 181 of the back metal layer 18, and then perform batch mask printing to ensure that the printed mask... The center line of mask 19 is collinear with the center line of the corresponding second contact hole 72 in the first direction X, thereby improving the printing accuracy of mask 19 and ensuring that the center line of the second fine grid 9 is collinear with the center line of the second contact hole 72 in the first direction X. Since the distance between the mask on the first contact hole 71 and the mask on the second contact hole 72 is fixed, by moving and adjusting the screen of the printing mask, the center line of the first fine grid 8 is simultaneously ensured to be collinear with the center line of the first contact hole 71 in the first direction X. Therefore, the alignment accuracy of the second fine grid 9 and the second contact hole 72 and the alignment accuracy of the first fine grid 8 and the first contact hole 71 can be improved, preventing the second fine grid 9 from shifting relative to the second contact hole 72 and the first fine grid 8 from shifting relative to the first contact hole 71. This ensures reliable contact between the second fine grid 9 and the second doped part 3 and reliable contact between the first fine grid 8 and the first doped part 2, achieving good current collection effect for the second fine grid 9 and the first fine grid 8, and ensuring good power generation efficiency of the battery.

[0041] As an embodiment of the present invention, the identification doping part 6 is connected to both the second doping part 3 and the third doping part 4.

[0042] In this embodiment, since the marking doping portion 6 connects the second doping portion 3 and the third doping portion 4, the presence of the marking doping portion 6 forms a leakage composite contact structure between the second doping portion 3 and the third doping portion 4. When the battery cell is blocked by an obstruction, the marking doping portion 6 forms a leakage point, and the marking doping portion 6 conducts between the adjacent second doping portion 3 and the third doping portion 4, which can reduce the reverse breakdown voltage of the back contact battery 100 when it is blocked, thereby improving the hot spot resistance performance of the back contact battery 100. Therefore, the marking doping part 6 provided in this embodiment has two advantages. First, the marking doping part 6 facilitates the formation of a raised structure 181 on the metal layer 18 of the back side 11 at the position of the marking doping part 6, which is raised relative to the surrounding area. This serves as a reference for alignment during the mask printing process, improving the mask printing accuracy and preventing the second fine grid 9 from shifting relative to the second contact hole 72 and the first fine grid 8 from shifting relative to the first contact hole 71. This ensures reliable contact between the second fine grid 9 and the second doping part 3, and reliable contact between the first fine grid 8 and the first doping part 2, achieving good current collection effect for the second fine grid 9 and the first fine grid 8, and ensuring good power generation efficiency of the battery. Second, the marking doping part 6 can play a role in resisting hot spots. Therefore, the marking doping part 6 can achieve both effects, and it is simple to process and has low implementation cost.

[0043] Please refer to the reference. Figure 5 As an embodiment of the present invention, the passivation layer 7 includes a marking portion 73 covering the marking doped portion 6, wherein the center line of the marking portion 73 along the first direction X is collinear with the center line of the marking doped portion 6 along the first direction X.

[0044] In this embodiment, after the passivation layer 7 is prepared, since the marking doped portion 6 is raised relative to the surrounding isolation region 112, the center line of the marking portion 73 along the first direction X is collinear with the center line of the marking doped portion 6 along the first direction X. This can be understood as the orthogonal projection of the center line of the marking portion 73 along the first direction X onto the silicon wafer 1 coinciding with the orthogonal projection of the center line of the marking doped portion 6 along the first direction X onto the silicon wafer 1. That is, both the orthogonal projection of the center line of the marking portion 73 along the first direction X onto the silicon wafer 1 and the orthogonal projection of the center line of the marking doped portion 6 along the first direction X onto the silicon wafer 1 are collinear with a central axis L. Since the marking portion 73 of the passivation layer 7 is also raised relative to the marking doped portion 6 in the surrounding isolation region 112, it facilitates the formation of a raised structure 181 at the corresponding marking portion 73 position on the metal layer 18 after the entire surface of the passivation layer 7 is formed. This serves as a reference for mask alignment, further improving the mask printing accuracy.

[0045] Please refer to the reference. Figure 2 , Figure 6 and Figure 7 As one embodiment of the present invention, it includes: Several first fine gates 8 are provided, each first fine gate 8 is disposed on a corresponding first contact hole 71, the first fine gate 8 passes through the corresponding first contact hole 71 and contacts the first doped part 2.

[0046] In this embodiment, a first contact hole 71 is provided in the passivation layer 7 at the position corresponding to the first doped portion 2. The first fine gate 8 passes through the corresponding first contact hole 71 and contacts the first doped portion 2, thereby achieving an ohmic contact between the first fine gate 8 and the first doped portion 2. The size of the first contact hole 71 is smaller than the size of the first doped portion 2; that is, the size of the first contact hole 71 along the first direction X is smaller than the size of the first doped portion 2 along the first direction X, and the size of the first contact hole 71 along the second direction Y is smaller than the size of the first doped portion 2 along the second direction Y.

[0047] As an embodiment of the present invention, the back contact battery 100 further includes: A plurality of second fine gates 9 are provided, each second fine gate 9 being disposed on a corresponding second contact hole 72, the second fine gate 9 passing through the corresponding second contact hole 72 and contacting the second doped portion 3.

[0048] In this embodiment, a second contact hole 72 is provided in the passivation layer 7 at the position corresponding to the second doped portion 3. The second fine gate 9 passes through the corresponding second contact hole 72 and contacts the second doped portion 3, thereby achieving ohmic contact between the second fine gate 9 and the second doped portion 3. The size of the second contact hole 72 is smaller than the size of the second doped portion 3; that is, the size of the second contact hole 72 along the first direction X is smaller than the size of the second doped portion 3 along the first direction X, and the size of the second contact hole 72 along the second direction Y is smaller than the size of the second doped portion 3 along the second direction Y.

[0049] In this embodiment of the invention, the number of marking doped portions 6 can be one, two, three or more, and the specific number of marking doped portions 6 is not limited. The center line of each marking doped portion 6 along the first direction X is collinear with the center line of the corresponding second contact hole 72 along the first direction X.

[0050] As an embodiment of the present invention, the number of marking doped portions 6 is at least two, and at least two marking doped portions 6 are located at diagonal positions of silicon wafer 1.

[0051] In this embodiment, there are at least two marking doped portions 6, and at least two marking doped portions 6 are distributed at opposite corners of the silicon wafer 1. That is, marking doped portions 6 are provided at at least two opposite corners of the silicon wafer 1. Since there are at least two marking doped portions 6 distributed at opposite corners of the silicon wafer 1, after the metal layer 18 is formed on the entire back surface 11, the metal layer 18 will form protrusions 181 at opposite corners of the silicon wafer 1 that match the positions of the marking doped portions 6. The protrusions 181 formed at opposite corners of the metal layer 18 serve as references for mask alignment. At least two protrusions 181 can be used to align with the corresponding masks, thereby further improving the mask printing accuracy. When the center line of the mask located at the opposite corner of the silicon wafer 1 along the first direction X is collinear with the center line of the corresponding protrusion 181 along the first direction X, it can be considered that the center line of the second contact hole 72 is collinear with the center line of the mask, which can further improve the mask printing accuracy.

[0052] As an embodiment of the present invention, the number of identification doped portions 6 is at least four, and identification doped portions 6 are provided at least at the four corners of the silicon wafer 1.

[0053] In this embodiment, each of the four corners of the silicon wafer 1 is provided with a doped marking portion 6. After the metal layer 18 is formed on the entire back surface 11, the metal layer 18 forms a protrusion structure 181 at each of the four corners of the silicon wafer 1 that matches the position of the doped marking portion 6. After printing the mask, the masks at the four corners of the silicon wafer 1 can be aligned with the corresponding protrusion structure 181. When the center line of the mask at each of the four corners is collinear with the center line of the corresponding protrusion structure 181, the mask printing accuracy is considered to meet the requirements, and the mask printing accuracy can be further improved. Moreover, when the doped marking portion 6 is connected to both the second doped portion 3 and the third doped portion 4, the increased number of doped marking portions 6 can further improve the hot spot resistance of the back contact cell 100.

[0054] As an embodiment of the present invention, the doping type of the marking doping part 6 and the third doping part 4 are the same, and the marking doping part 6 and the third doping part 4 are integrally formed.

[0055] In this embodiment, the doping type of the marking doped portion 6 and the third doped portion 4 is the same. For example, both the marking doped portion 6 and the third doped portion 4 can be P-type doped layers or N-type doped layers. The marking doped portion 6 and the third doped portion 4 are integrally formed, allowing them to be fabricated in one step. The marking doped portion 6 does not require separate processing. After the first doped portion 2, the second doped portion 3, and the third doped portion 4 are fabricated, when the isolation region 112 is formed by laser, it is only necessary to control that a portion of the area between the third doped portion 4 and the second doped portion 3 is not laser-etched, that is, the isolation region 112 is not formed in a portion of the area between the third doped portion 4 and the second doped portion 3. Thus, the marking doped portion 6 is formed by retaining a portion of the third doped portion 4 between the third doped portion 4 and the second doped portion 3. The marking doped portion 6 does not need to be fabricated separately, making its fabrication simple and cost-effective.

[0056] In another embodiment of the present invention, the doping type of the marking doping part 6 and the second doping part 3 are the same, and the marking doping part 6 and the second doping part 3 are integrally formed.

[0057] In this embodiment, the doping type of the marking doped portion 6 and the second doped portion 3 is the same. For example, both the marking doped portion 6 and the second doped portion 3 can be P-type doped layers or N-type doped layers. The marking doped portion 6 and the second doped portion 3 are integrally formed, allowing them to be fabricated in one step. The marking doped portion 6 does not require separate processing. After the first doped portion 2, the second doped portion 3, and the third doped portion 4 are fabricated, during the laser formation of the isolation region 112, a portion of the area between the third doped portion 4 and the second doped portion 3 is not laser-etched. This leaves a portion of the second doped portion 3 between the third doped portion 4 and the second doped portion 3, forming the marking doped portion 6. Therefore, the marking doped portion 6 does not need to be fabricated separately, making its fabrication simple and cost-effective.

[0058] As an embodiment of the present invention, one end of the marking doped part 6 is connected to the third doped part 4, and the other end is superimposed on the second doped part 3.

[0059] In this embodiment, the marking doped part 6 and the third doped part 4 are integrally formed. One end of the marking doped part 6 is connected to the third doped part 4, and the other end is superimposed on the second doped part 3. That is, the marking doped part 6 protrudes relative to the second doped part 3, so that the marking doped part 6 and the second doped part 3 are located on different planes. This can increase the protrusion of the passivation layer 7 and the metal layer 18 on the back side 11 at the position of the marking doped part 6, thereby further facilitating the mask alignment during the mask printing process.

[0060] In another embodiment of the present invention, one end of the marking doped part 6 is connected to the second doped part 3, and the other end is superimposed on the third doped part 4.

[0061] In this embodiment, the marking doped part 6 and the second doped part 3 are integrally formed. One end of the marking doped part 6 is connected to the second doped part 3, and the other end is stacked on the second doped part 3, so that the marking doped part 6 protrudes relative to the third doped part 4, which can further improve the protrusion of the passivation layer 7 and the metal layer 18 on the back side 11 at the marking doped part 6 position, and further facilitate the mask alignment in the mask printing process.

[0062] As an embodiment of the present invention, the size of the doped portion 6 along the first direction X is 100 micrometers to 180 micrometers.

[0063] In this embodiment, the size of the marking doped part 6 along the first direction X is controlled to be 100 micrometers to 180 micrometers, so that the size of the protrusion structure 181 formed on the back side 11 along the first direction X is more suitable, which is beneficial to the mask alignment during the mask printing process; moreover, when the marking doped part 6 is connected to the second doped part 3 and the third doped part 4 at the same time, the back contact battery 100 can achieve good anti-hot spot performance.

[0064] As an embodiment of the present invention, the size of the doped portion 6 along the second direction Y is 100 micrometers to 180 micrometers.

[0065] In this embodiment, the size of the marking doped part 6 along the second direction Y is controlled to be 100 micrometers to 180 micrometers, so that the size of the protrusion structure 181 formed on the back side 11 along the second direction Y is more suitable, which is beneficial to the mask alignment during the mask printing process; moreover, when the marking doped part 6 is connected to the second doped part 3 and the third doped part 4 at the same time, the back contact battery 100 can achieve good anti-hot spot performance.

[0066] As an embodiment of the present invention, the surface of the doped portion 6 near the passivation layer 7 may be provided with grooves or protrusions.

[0067] In this embodiment, the surface of the doped marking portion 6 near the passivation layer 7 is provided with grooves or protrusions, so that after the metal layer 18 is formed on the entire back surface 11, the surface of the protrusion structure 181 formed by the metal layer 18 can also form corresponding grooves or protrusions at the position of the doped marking portion 6, making the protrusion structure 181 of the metal layer 18 more identifiable, making it easier for the processing personnel to quickly find the location of the doped marking portion 6 after the entire metal layer 18 is prepared, and facilitating mask alignment.

[0068] In one embodiment of the present invention, the first doped part 2, the marking doped part 6, and the third doped part 4 are all N-type doped parts, and the second doped part 3 is a P-type doped part.

[0069] In this embodiment, the marking doped portion 6 extends from the third doped portion 4 to the second doped portion 3. The first doped portion 2, the marking doped portion 6, and the third doped portion 4 are all N-type doped portions, and the second doped portion 3 is a P-type doped portion, which facilitates the processing of the back contact battery 100. In some other embodiments, the first doped portion 2, the marking doped portion 6, and the third doped portion 4 may all be P-type doped portions, and the second doped portion 3 may be an N-type doped portion.

[0070] In another embodiment of the present invention, the first doped portion 2 and the third doped portion 4 are both P-type doped portions, and the identifying doped portion 6 and the second doped portion 3 are N-type doped portions; or, the first doped portion 2 and the third doped portion 4 are both N-type doped portions, and the identifying doped portion 6 and the second doped portion 3 are P-type doped portions.

[0071] In this embodiment, the marking doped portion 6 extends from the second doped portion 3 to the third doped portion 4, and at this time the marking doped portion 6 and the second doped portion 3 have the same doping type.

[0072] Please refer to the reference. Figure 1 and Figure 2 As one embodiment of the present invention, it further includes: A first main gate 15 is disposed on the third doped section 4, the first main gate 15 is connected to at least a portion of the first fine gates 8, and the second fine gates 9 are intermittently disposed at the position of the first main gate 15.

[0073] In this embodiment, a first main gate 15 is provided on the third doped portion 4. The first main gate 15 is connected to at least a portion of the first fine gates 8. The first main gate 15 is used to collect the current of the first fine gates 8. Moreover, the first main gate 15 is connected to the solder ribbon, which facilitates the connection of the back contact battery 100 to the solder ribbon, and makes it convenient for the back contact batteries 100 to be connected in series to form a battery string. The second fine gate 9 is intermittently provided at the position of the first main gate 15, that is, the second fine gate 9 is disconnected at the position of the first main gate 15, so that the second fine gate 9 is not connected to the first main gate 15, thereby achieving insulation between the second fine gate 9 and the first main gate 15.

[0074] As an embodiment of the present invention, there are multiple third doped portions 4, and the multiple third doped portions 4 are arranged sequentially at intervals along the first direction X.

[0075] In this embodiment, there are multiple third doped portions 4, which are arranged sequentially at intervals along the first direction X, and a first main gate 15 is correspondingly arranged on each third doped portion 4.

[0076] As one embodiment of the present invention, it also includes: A fourth doped portion 5 is provided on the back side 11. The fourth doped portion 5 extends along the second direction Y. The fourth doped portion 5 and the second doped portion 3 have the same doping type. The fourth doped portion 5 is connected to the second doped portion 3. The fourth doped portion 5 and the third doped portion 4 are alternately arranged along the first direction X. The second main gate 16 is disposed on the fourth doped section 5, the second main gate 16 is connected to at least a portion of the second fine gates 9, and the first fine gate 8 is intermittently disposed at the position of the second main gate 16.

[0077] In this embodiment, a second main gate 16 is provided on the fourth doped part 5. The fourth doped part 5 and the second doped part 3 have the same doping type. The fourth doped part 5 is connected to the second doped part 3. There are multiple fourth doped parts 5 and multiple third doped parts 4. The fourth doped part 5 and the third doped part 4 are alternately spaced along the first direction X, so that the first main gate 15 and the second main gate 16 are alternately spaced along the first direction X.

[0078] In this embodiment, the first main grid 15 and the second main grid 16 are both extended along the second direction Y. Since the first main grid 15 and the second main grid 16 are provided, they can be connected to the solder strip, which facilitates the welding between the back contact battery 100 and the solder strip.

[0079] As an embodiment of the present invention, the silicon wafer 1 includes a first edge 101 and a second edge 102 disposed opposite to each other along the second direction Y. A first main gate 15 and a second main gate 16 are disposed on the back surface 11 near the first edge 101 and the second edge 102, respectively. The first main gate 15 near the first edge 101 is spaced apart from the first main gate 15 near the second edge 102, and the second main gate 16 near the first edge 101 is spaced apart from the second main gate 16 near the second edge 102.

[0080] In this embodiment, the first main gate 15 and the second main gate 16 are only provided near the first edge 101 and the second edge 102 of the silicon wafer 1. The back contact cell 100 near the first edge 101 and the second edge 102 can be welded to the solder ribbon using the first main gate 15 and the second main gate 16 respectively. Since the first main gate 15 near the first edge 101 is spaced apart from the first main gate 15 near the second edge 102, and the second main gate 16 near the first edge 101 is spaced apart from the second main gate 16 near the second edge 102, the middle area of ​​the back side 11 of the silicon wafer 1 does not have the first main gate 15 and the second main gate 16. The first fine gate 8 and the second fine gate 9 in the middle area of ​​the back side 11 of the silicon wafer 1 are directly welded to the solder ribbon. This can reduce the length of the first main gate 15 and the second main gate 16, reduce the amount of paste used, and help reduce costs. Furthermore, by using the first main gate 15 and the second main gate 16 to weld to the solder ribbon near the edge of the silicon wafer 1, the first fine gate 8 and the second fine gate 9 can be prevented from breaking at the edge of the back contact cell 100.

[0081] As an embodiment of the present invention, the ratio of the dimension L1 of the first main gate 15 along the second direction Y to the dimension of the silicon wafer 1 along the second direction Y is 0.05 to 0.1.

[0082] In this embodiment, the dimension of silicon wafer 1 along the second direction Y is the total length of silicon wafer 1 along the second direction Y. The ratio of the dimension L1 of the first main gate 15 along the second direction Y to the dimension of silicon wafer 1 along the second direction Y is controlled to be 0.05~0.1, ensuring that the dimension L1 of the first main gate 15 along the second direction Y is within a reasonable range. This reduces the length of the first main gate 15, reduces the amount of paste used in the first main gate 15, and also ensures good soldering between the first main gate 15 and the solder ribbon.

[0083] As an embodiment of the present invention, the ratio of the dimension L2 of the second main gate 16 along the second direction Y to the dimension of the silicon wafer 1 along the second direction Y is 0.05 to 0.1.

[0084] In this embodiment, the ratio of the dimension L2 of the second main gate 16 along the second direction Y to the dimension of the silicon wafer 1 along the second direction Y is controlled to be 0.05~0.1. This can reduce the length of the second main gate 16, reduce the amount of paste used in the second main gate 16, and also ensure good welding between the second main gate 16 and the solder strip.

[0085] This invention also provides a battery assembly including the back contact battery described in the above embodiments. It should be noted that this battery assembly has the same or similar beneficial effects as the back contact battery, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0086] In this embodiment, multiple back-contact batteries in the battery assembly can be connected in series to form a battery string, thereby achieving series current output. For example, the battery cells can be connected in series by setting solder strips (busbars, interconnecting strips), conductive backplates, etc.

[0087] It is understood that in such embodiments, the battery assembly may also include a metal frame, a backsheet, photovoltaic glass, and an encapsulating film. The encapsulating film may be filled between the front and back surfaces of the back-contact battery, the photovoltaic glass, adjacent battery cells, etc. As a filler, it may be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulating film may be an EVA film or a POE film, and the specific choice can be made according to the actual situation, without limitation.

[0088] Photovoltaic glass can be applied to the encapsulating film on the front side of the back contact battery. This photovoltaic glass can be ultra-clear glass, possessing high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can achieve a light transmittance of over 92%, protecting the back contact battery while minimizing impact on its efficiency. Simultaneously, the encapsulating film bonds the photovoltaic glass and the back contact battery together, providing sealing, insulation, and waterproofing / moisture protection for the battery.

[0089] The backsheet can be attached to the adhesive film on the back side of the back contact cell. The backsheet protects and supports the back contact cell, providing reliable insulation, water resistance, and aging resistance. Multiple backsheet options are available, typically including tempered glass, acrylic glass, aluminum alloy TPT composite adhesive film, etc., and the specific choice depends on the specific circumstances and is not limited here. The backsheet, back contact cell, adhesive film, and photovoltaic glass can be mounted on a metal frame. The metal frame serves as the main external support structure for the entire battery module, providing stable support and installation. For example, the battery module can be installed at the desired location using the metal frame.

[0090] This invention also provides a photovoltaic system, which includes the battery module described in the above embodiments. It should be noted that this photovoltaic system has the same or similar beneficial effects as the back-contact battery described above, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0091] In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system are not limited to these; that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0092] In the description of this specification, references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0093] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A back-contact battery, characterized in that, include: Silicon wafers; A first doped portion and a second doped portion with opposite doping types are disposed on the back side of the silicon wafer. The first doped portion and the second doped portion are both extended along a first direction. The first doped portion and the second doped portion are alternately spaced along a second direction, and the second direction intersects the first direction. A third doped portion is provided on the back side and has the same doping type as the first doped portion. The third doped portion extends along the second direction and is connected to the first doped portion. An isolation region is provided between the first doped portion and the second doped portion, and between the second doped portion and the third doped portion. An identification doping portion is provided between the second doping portion and the third doping portion; A passivation layer covers the first doped portion, the second doped portion, the third doped portion, the marking doped portion, and the isolation region. The passivation layer has a first contact hole for setting a first fine gate at the position corresponding to the first doped portion, and a second contact hole for setting a second fine gate at the position corresponding to the second doped portion. The marking doped portion and the corresponding second contact hole are opposite each other along the first direction, and the center line of the marking doped portion along the first direction is collinear with the center line of the corresponding second contact hole along the first direction.

2. The back contact battery according to claim 1, characterized in that, The identification doped portion is connected to at least one of the second doped portion and the third doped portion.

3. The back contact battery according to claim 1, characterized in that, The identification doping part connects both the second doping part and the third doping part.

4. The back contact battery according to claim 1, characterized in that, The passivation layer includes a marking portion covering the marking doped portion, wherein the center line of the marking portion along the first direction is collinear with the center line of the marking doped portion along the first direction.

5. The back contact battery according to claim 1, characterized in that, include: A plurality of first fine gates are provided, each of the first fine gates being disposed on a corresponding first contact hole, the first fine gate passing through the corresponding first contact hole and contacting the first doped portion.

6. The back contact battery according to claim 5, characterized in that, Also includes: A plurality of second fine gates are provided, each second fine gate being disposed on a corresponding second contact hole, the second fine gate passing through the corresponding second contact hole and contacting the second doped portion.

7. The back contact battery according to claim 1, characterized in that, The number of the marking doped portions is at least two, and at least two of the marking doped portions are located at diagonal positions on the silicon wafer.

8. The back contact battery according to claim 1, characterized in that, The number of the marking doped portions is at least four, and the marking doped portions are provided at least at the four corners of the silicon wafer.

9. The back contact battery according to claim 1, characterized in that, The identification doping part and the third doping part have the same doping type, and the identification doping part and the third doping part are integrally formed.

10. The back contact battery according to claim 1, characterized in that, The identification doping part has the same doping type as the second doping part, and the identification doping part and the second doping part are integrally formed.

11. The back contact battery according to claim 9, characterized in that, One end of the marking doped part is connected to the third doped part, and the other end is superimposed on the second doped part.

12. The back contact battery according to claim 10, characterized in that, One end of the marking doped portion is connected to the second doped portion, and the other end is superimposed on the third doped portion.

13. The back contact battery according to claim 1, characterized in that, The size of the doped marking portion along the first direction is 100 micrometers to 180 micrometers.

14. The back contact battery according to claim 1, characterized in that, The size of the doped part along the second direction is 100 micrometers to 180 micrometers.

15. The back contact battery according to claim 1, characterized in that, The first doped portion, the identification doped portion, and the third doped portion are all N-type doped portions, and the second doped portion is a P-type doped portion.

16. The back contact battery according to claim 6, characterized in that, Also includes: A first main gate is disposed on the third doped portion, the first main gate is connected to at least a portion of the first fine gates, and the second fine gates are intermittently disposed at the location of the first main gate.

17. The back contact battery according to claim 16, characterized in that, Also includes: A fourth doped portion is provided on the back side, the fourth doped portion extends along the second direction, the fourth doped portion and the second doped portion have the same doping type, the fourth doped portion is connected to the second doped portion, and the fourth doped portion and the third doped portion are alternately spaced along the first direction; A second main gate is disposed on the fourth doped portion, the second main gate is connected to at least a portion of the second fine gates, and the first fine gates are intermittently disposed at the location of the second main gate.

18. The back contact battery according to claim 17, characterized in that, The silicon wafer includes a first edge and a second edge disposed opposite to each other along the second direction. The first main gate and the second main gate are disposed on the back side near the first edge and the second edge, respectively. The first main gate near the first edge is spaced apart from the first main gate near the second edge, and the second main gate near the first edge is spaced apart from the second main gate near the second edge.

19. The back contact battery according to claim 18, characterized in that, The ratio of the dimension of the first main gate along the second direction to the dimension of the silicon wafer along the second direction is 0.05 to 0.1; and / or, the ratio of the dimension of the second main gate along the second direction to the dimension of the silicon wafer along the second direction is 0.05 to 0.

1.

20. A battery assembly, characterized in that, Including the back contact battery as described in any one of claims 1 to 19.

21. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 20.

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