Back contact cell and photovoltaic module

Abstract

The present application discloses a back contact cell and a photovoltaic module, and relates to the field of photovoltaic technology. The back contact cell includes a substrate, a back doping layer, a passivation layer and an electrode in order from top to bottom along the thickness direction of the substrate, wherein the back doping layer includes a first doping region and a second doping region, and the first doping region and the second doping region have opposite conductivity types; a plurality of first through holes are opened in the region corresponding to the first doping region of the passivation layer, and a plurality of second through holes are opened in the region corresponding to the second doping region of the passivation layer; the electrode includes a first electrode and a second electrode, the first electrode passes through the first through hole to make conductive contact with the first doping region, and the second electrode passes through the second through hole to make conductive contact with the second doping region; the total area of ​​all the first through holes opened in the passivation layer is greater than the total area of ​​all the second through holes. The opening method of the first through hole and the second through hole is designed according to the difference between the P region and the N region of the back contact cell, so as to reduce the performance loss of the back contact cell.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaics, in particular to a back contact battery and a photovoltaic component. Background Art

[0002] A back-contact cell refers to a solar cell in which the light-facing side of the cell has no electrode, and the positive and negative electrodes are arranged on the backlight side of the cell. This can reduce the shading of the electrode to the cell, increase the short-circuit current of the cell, and improve the energy conversion efficiency of the cell.

[0003] In the prior art, the electrodes of the back contact battery are generally made of silver paste. With the continuous increase in photovoltaic production, the demand for silver paste continues to increase, resulting in soaring silver paste prices and increased battery costs. In order to reduce battery costs, some companies use low-priced metals such as aluminum and copper instead of silver paste to make electrodes. Specifically, it is necessary to laser groove the passivation layer of the back contact battery, and then deposit low-priced metals such as aluminum and copper in the grooved area to form electrodes. However, in the prior art, when the passivation layer in the P-type doped area and the N-type doped area of ​​the back contact battery is laser grooved, the grooved areas of the P-type doped area and the N-type doped area are equal, and there is a difference in the conductivity of the P-type doped area and the N-type doped area, which leads to a large difference in the contact resistance between the P-type doped area and the N-type doped area and the electrode, which in turn leads to a large difference in the current in the P-type doped area and the N-type doped area, and the battery has current loss, which reduces the performance of the back contact battery. Utility Model Content

[0004] The purpose of the present application is to provide a back-contact cell and a photovoltaic module, so as to design the opening method of the first through hole and the second through hole according to the difference between the P region and the N region of the back-contact cell, so as to reduce the performance loss of the back-contact cell.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] A back contact battery comprises a substrate, a back doping layer, a passivation layer and an electrode in order from top to bottom along the thickness direction of the substrate, wherein:

[0007] The back doped layer includes a first doped region and a second doped region, and the first doped region and the second doped region have opposite conductivity types; a plurality of first through holes are opened in the region of the passivation layer corresponding to the first doped region, and a plurality of second through holes are opened in the region of the passivation layer corresponding to the second doped region; the electrode includes a first electrode and a second electrode, the first electrode passes through the first through hole to be in conductive contact with the first doped region, and the second electrode passes through the second through hole to be in conductive contact with the second doped region;

[0008] The total area of ​​all first through holes formed in the passivation layer is greater than the total area of ​​all second through holes;

[0009] The first through hole and the second through hole have the same shape and the same size, and the number of the first through holes is greater than the number of the second through holes; or, the first through hole and the second through hole have different shapes; or, the first through hole and the second through hole have the same shape and different sizes, and the number of the first through holes is different from the number of the second through holes.

[0010] The key point is that the total area of ​​all first through holes opened in the passivation layer is greater than the total area of ​​all second through holes, that is, the total area of ​​all first through holes opened in the passivation layer is greater than the total area of ​​all second through holes opened in the passivation layer. Since there is a difference in conductivity between the first doped region and the second doped region, if the first doped region is a P-type doped region and the second doped region is an N-type doped region, that is, there is a difference in conductivity between the P-type doped region and the N-type doped region, and the conductivity of the P-type doped region is less than that of the N-type doped region, the contact area between the first electrode and the P-type doped region needs to be greater than the contact area between the second electrode and the N-type doped region. In the present application, the total area of ​​all first through holes in the region corresponding to the passivation layer and the first doped region is greater than the total area of ​​all second through holes in the region corresponding to the passivation layer and the second doped region. In this way, the contact area between the first electrode and the P-type doped region can be greater than the contact area between the second electrode and the N-type doped region, thereby making the contact resistance between the P-type doped region and the first electrode and the contact resistance between the N-type doped region and the second electrode equal or closer, and the contact resistance between the P-type doped region and the N-type doped region and the electrodes is more balanced, so that the difference between the current in the P-type doped region and the current in the N-type doped region is reduced, thereby reducing the current loss of the battery and ensuring the performance of the battery.

[0011] In one implementation, the first doped region is a P-type doped region, the second doped region is an N-type doped region, the number of columns of first through holes opened in the first doped region is different from the number of columns of second through holes opened in the second doped region; the number of columns of first through holes and / or the number of columns of second through holes is greater than or equal to 2, and a column of second through holes is set between two adjacent columns of first through holes and / or a column of first through holes is set between two adjacent columns of second through holes. In this way, the distribution of the plurality of first through holes and the second through holes can be made more uniform, ensuring uniform extraction of current.

[0012] In one implementation, the first through holes and the second through holes have the same shape and size, and the spacing between the centers of adjacent first through holes in the same column is smaller than the spacing between the centers of adjacent second through holes in the same column. In this technical solution, the number of first through holes in each column is greater than the number of second through holes in each column, thereby ensuring that the total area of ​​all first through holes opened in the passivation layer is greater than the total area of ​​all second through holes.

[0013] In one implementation, the first doped region is a P-type doped region, the second doped region is an N-type doped region, a plurality of groups of first through holes are arranged in the first doped region, a plurality of groups of second through holes are arranged in the second doped region, a group of second through holes is arranged between two adjacent groups of first through holes, and a group of first through holes is arranged between two adjacent groups of second through holes; the number of columns of first through holes included in each group of first through holes is greater than the number of columns of second through holes included in each group of second through holes, so that it is easier to make the total number of first through holes greater than the total number of second through holes, and it is easier to achieve that the total area of ​​all first through holes opened in the passivation layer is greater than the total area of ​​all second through holes.

[0014] In one implementation, each group of first through holes includes two columns of first through holes, and the two columns of first through holes in each group are staggered. Compared with the alignment of the two columns of first through holes in each group, the staggered arrangement of the two columns of first through holes in each group can further ensure the uniformity of current extraction. In this embodiment, each group of second through holes includes one column of second through holes to further simplify the process.

[0015] In one implementation, the first through holes and the second through holes have the same shape and size, and each group of first through holes includes two columns of first through holes, each group of second through holes includes one column of second through holes, and the spacing between the centers of adjacent first through holes in the same column is equal to the spacing between the centers of adjacent second through holes in the same column. The number of columns of first through holes is twice the number of columns of second through holes, and the spacing between the centers of adjacent first through holes in the same column is equal to the spacing between the centers of adjacent second through holes in the same column, so as to ensure that the number of first through holes is twice the number of second through holes, thereby ensuring that the total area of ​​all first through holes opened in the passivation layer is greater than the total area of ​​all second through holes.

[0016] In one implementation, the area of ​​a single first through hole is greater than the area of ​​a single second through hole, and the number of the first through holes is greater than or less than the number of the second through holes; or,

[0017] The area of ​​a single first through hole is smaller than the area of ​​a single second through hole, and the number of first through holes is greater than the number of second through holes. In short, as long as the total area of ​​all first through holes opened in the passivation layer is greater than the total area of ​​all second through holes, it can be set specifically according to the complexity of the process and the uniformity of current distribution.

[0018] In one implementation, the first through hole and the second through hole have different shapes, the area of ​​a single first through hole is larger than the area of ​​a single second through hole, and the spacing between the centers of adjacent first through holes in the same column is equal to the spacing between the centers of adjacent second through holes in the same column. This arrangement makes it easier to distinguish the first doped region from the second doped region, and facilitates distinguishing the first doped region from the second doped region in subsequent processing.

[0019] In one implementation, in the same column of first through holes, the spacing between the centers of adjacent first through holes is 25 μm to 110 μm, so as to accommodate back contact batteries of different sizes; and / or,

[0020] In the second through holes in the same column, the spacing between the centers of adjacent second through holes is 25 μm to 110 μm, so as to accommodate back contact batteries of different sizes.

[0021] In one implementation, the first through hole and / or the second through hole comprises a circular hole, an elliptical hole and / or a polygonal hole; thus, the first through hole and / or the second through hole have a regular shape and are easy to process and manufacture;

[0022] The diameter of the circular hole is 10 μm to 45 μm; or the polygonal hole includes a square hole, and the side length of the square hole is 10 μm to 45 μm.

[0023] In one implementation, the first doped regions and the second doped regions are alternately distributed in an interdigitated manner.

[0024] A photovoltaic module comprises any of the above-mentioned back-contact cells. Compared with the prior art, the photovoltaic module provided by the embodiment of the present application has the same beneficial effects as the above-mentioned back-contact cells, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0026] Figure 1 A cross-sectional view of a back contact battery provided in an embodiment of the present application;

[0027] Figure 2 A distribution diagram of the first through holes and the second through holes provided in the passivation layer provided in the first embodiment of the present application;

[0028] Figure 3 A distribution diagram of the first through holes and the second through holes provided in the passivation layer of the second embodiment of the present application;

[0029] Figure 4 A distribution diagram of the first through holes and the second through holes provided in the passivation layer provided in the third embodiment of the present application;

[0030] Figure 5 A distribution diagram of the first through holes and the second through holes provided in the passivation layer provided in the fourth embodiment of the present application;

[0031] Figure 6 A distribution diagram of the first through holes and the second through holes provided in the passivation layer provided in the fifth embodiment of the present application;

[0032] Figure 7 This is a distribution diagram of the first through holes and the second through holes opened in the passivation layer provided in Example 6 of the present application.

[0033] Reference numerals:

[0034] A-substrate, B-back doping layer, C-passivation layer, D-electrode;

[0035] 1-first doped region, 1a-first through hole, 2-second doped region, 2a-second through hole, X-a column of first through holes, Y-a column of second through holes, Z-a group of first through holes. DETAILED DESCRIPTION

[0036] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0037] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0038] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0039] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", etc., indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0040] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] See also Figure 1 The back contact battery provided in the embodiment of the present application includes a substrate A, a back doping layer B, a passivation layer C and an electrode D in order from top to bottom along the thickness direction of the substrate A. Among them, the substrate A can be an n-type semiconductor substrate or a p-type semiconductor substrate. The material of the substrate A can be silicon. The substrate A has a first surface and a second surface relative to each other. In practical applications, the first surface can face the sun, or the second surface can face the sun, the side facing the sun is the light-facing surface, and the side facing away from the sun is the backlight surface. The back doping layer B, the passivation layer C and the electrode D are all located on the backlight surface of the substrate A.

[0042] The back doping layer B includes a first doping region 1 and a second doping region 2, and the first doping region 1 and the second doping region 2 have opposite conductivity types. Specifically, the first doping region 1 is a P-type doping region, for example, the first doping region 1 is a boron doping region or a gallium doping region. The P-type doping region can be a boron or gallium back surface field formed by doping directly on the backlight surface of the substrate A, and the specific P-type doping region can be formed by laser doping process, thermal diffusion process, ion implantation process, doping source coating advancement process, etc. In addition, the second doping region 2 is an N-type doping region, for example, the second doping region 2 is a phosphorus doping region. The N-type doping region can be formed by thermal diffusion process, ion implantation process, doping source coating advancement process, etc.

[0043] The passivation layer C is located on the side of the back doped layer B away from the substrate A, and the passivation layer C covers the back doped layer B. Preferably, a tunneling oxide layer can be provided between the N-type doped region and the substrate A, and the P-type doped region is directly in contact with the passivation layer C. The material of the passivation layer C is a dielectric material. The material of the passivation layer C can be one or more of self-hydrogenated amorphous silicon, silicon oxynitride, silicon carbide, silicon nitride, aluminum oxide, and silicon oxide. The formation process of the passivation layer C can be a physical vapor deposition process or a chemical vapor deposition process.

[0044] like Figure 2-Figure 7As shown, a plurality of first through holes 1a are provided in the region corresponding to the first doping region 1 of the passivation layer C, and a plurality of second through holes 2a are provided in the region corresponding to the second doping region 2 of the passivation layer C. The electrode D includes a first electrode and a second electrode, the first electrode passes through the first through hole 1a to be in conductive contact with the first doping region 1, and the second electrode passes through the second through hole 2a to be in conductive contact with the second doping region 2. The materials of the first electrode and the second electrode may include one or more of silver, copper, aluminum, nickel, titanium, tungsten, and tin. In practical applications, the first electrode and the second electrode may be formed by a metallization process. Specifically, the metallization process may be one or more of a PVD process, a screen printing process, an electroplating process, an electroless plating process, a laser transfer process, and a spraying process.

[0045] The first through hole 1a and the second through hole 2a can be formed by a laser film opening process, or by etching with an etching slurry. Preferably, the first through hole 1a and the second through hole 2a are formed by a laser film opening process, so that the shapes of the first through hole 1a and the second through hole 2a are more regular, the opening edges are neat and burr-free, and the laser film opening process is conducive to accurately controlling the sizes of the first through hole 1a and the second through hole 2a.

[0046] The key point is that the total area of ​​all first through holes 1a opened in the passivation layer C is greater than the total area of ​​all second through holes 2a. That is, the total area of ​​all first through holes 1a opened in the passivation layer C is greater than the total area of ​​all second through holes 2a opened in the passivation layer C. Since there is a difference in conductivity between the first doped region 1 and the second doped region 2, that is, there is a difference in conductivity between the P-type doped region and the N-type doped region, and the conductivity of the P-type doped region is smaller than that of the N-type doped region, the contact area between the first electrode and the P-type doped region needs to be larger than the contact area between the second electrode and the N-type doped region. In the present application, the total area of ​​all first through holes 1a in the region corresponding to the passivation layer C and the first doped region 1 is larger than the total area of ​​all second through holes 2a in the region corresponding to the passivation layer C and the second doped region 2. In this way, the contact area between the first electrode and the P-type doped region can be larger than the contact area between the second electrode and the N-type doped region, thereby making the contact resistance between the P-type doped region and the first electrode and the contact resistance between the N-type doped region and the second electrode equal or closer, and the contact resistance between the P-type doped region and the N-type doped region and the electrodes is more balanced, so that the difference between the current in the P-type doped region and the current in the N-type doped region is reduced, thereby reducing the current loss of the battery and ensuring the performance of the battery.

[0047] Specifically, Figure 2-Figure 5As shown, the first through hole 1a and the second through hole 2a have the same shape and size, that is, the first through hole 1a and the second through hole 2a have exactly the same shape and size, and the number of the first through holes 1a is greater than the number of the second through holes 2a, so as to ensure that the total area of ​​all the first through holes 1a opened in the passivation layer C is greater than the total area of ​​all the second through holes 2a opened in the passivation layer C. With such an arrangement, the laser film opening path is simple and convenient for processing and manufacturing.

[0048] Or, if Figure 6 As shown, the first through hole 1a and the second through hole 2a have the same shape and different sizes, and the number of the first through hole 1a is different from the number of the second through hole 2a. In this embodiment, the first through hole 1a and the second through hole 2a have the same shape, which can be square or circular, but the first through hole 1a and the second through hole 2a have different sizes, and the number of the first through hole 1a is different from the number of the second through hole 2a. This arrangement makes it easier to distinguish the first doped region 1 from the second doped region 2, and facilitates distinguishing the first doped region 1 from the second doped region 2 during subsequent processing.

[0049] Or, if Figure 7 As shown, the shapes of the first through hole 1a and the second through hole 2a are different, and the shapes of the first through hole 1a and the second through hole 2a can be arbitrarily set according to actual needs. This scheme also facilitates distinguishing the first doped region 1 and the second doped region 2, and facilitates distinguishing the first doped region 1 and the second doped region 2 in subsequent processing.

[0050] In order to make the first through holes 1a more evenly distributed in the first doping region 1, and the second through holes 2a more evenly distributed in the second doping region 2, and to ensure the uniformity of the current in the first doping region 1 and the second doping region 2, the number of columns of the first through holes 1a opened in the first doping region 1 is the same as the number of columns of the second through holes 2a opened in the second doping region 2, the number of columns of the first through holes 1a and the number of columns of the second through holes 2a are greater than or equal to 2, and a column of second through holes is arranged between two adjacent columns of first through holes, and a column of first through holes is arranged between two adjacent columns of second through holes. That is, multiple columns of first through holes 1a and multiple columns of first through holes 1a are arranged at intervals, and multiple columns of first through holes 1a and multiple columns of second through holes 2a are arranged in sequence along the length direction or width direction of the back contact battery. Specifically, between any two adjacent columns of first through holes 1a, there is a column of second through holes, and between any two adjacent columns of second through holes 2a, there is a column of first through holes 1a. Figure 2 The middle X region is a row of first through holes 1a. Figure 2 The middle Y region is a row of second through holes 2a, so that the distribution of the plurality of first through holes 1a and second through holes 2a is more uniform, thereby ensuring uniform extraction of current.

[0051] In the above embodiment, the first through holes 1a and the second through holes 2a have the same shape and size, and the spacing between the centers of adjacent first through holes 1a in the same column is smaller than the spacing between the centers of adjacent second through holes 2a in the same column. In this technical solution, the number of first through holes 1a in each column is greater than the number of second through holes 2a in each column, thereby ensuring that the total area of ​​all first through holes 1a opened in the passivation layer C is greater than the total area of ​​all second through holes 2a. For example, Figure 2 As shown, the first through hole 1a and the second through hole 2a are both circular holes, and the diameters of the first through hole 1a and the second through hole 2a are equal, and the diameters of the first through hole 1a and the second through hole 2a can be 20μm, 30μm or 40μm, etc.; the spacing L1 between the centers of adjacent first through holes 1a in the same column can be 25μm-45μm, and specifically the spacing L1 between the centers of adjacent first through holes 1a in the same column is 25μm, 35μm or 40μm; the spacing L2 between the centers of adjacent second through holes 2a can be 40μm-60μm, and specifically the spacing L2 between the centers of adjacent second through holes 2a in the same column is 40μm, 45μm, 50μm, 55μm or 60μm.

[0052] like Figure 3 As shown, the first through hole 1a and the second through hole 2a are both square holes, and the side lengths of the first through hole 1a and the second through hole 2a are equal. The side lengths of the first through hole 1a and the second through hole 2a may be 10μm-20μm, and specifically the side lengths of the first through hole 1a and the second through hole 2a are 10μm, 15μm or 20μm. The spacing L1 between the centers of adjacent first through holes 1a in the same column may be 25μm-45μm, and specifically the spacing L1 between the centers of adjacent first through holes 1a in the same column is 25μm, 35μm or 40μm; the spacing L2 between the centers of adjacent second through holes 2a in the same column may be 40μm-60μm, and specifically the spacing L2 between the centers of adjacent second through holes 2a in the same column is 40μm, 45μm, 50μm, 55μm or 60μm.

[0053] like Figure 4 As shown, the first through hole 1a and the second through hole 2a are both elliptical holes, and the major axis and the minor axis of the first through hole 1a and the second through hole 2a are equal. The spacing L1 between the centers of adjacent first through holes 1a in the same column can be 25μm-45μm, and specifically the spacing L1 between the centers of adjacent first through holes 1a in the same column is 25μm, 35μm or 40μm; the spacing L2 between the centers of adjacent second through holes 2a in the same column can be 40μm-60μm, and specifically the spacing L2 between the centers of adjacent second through holes 2a in the same column is 40μm, 45μm, 50μm, 55μm or 60μm.

[0054] like Figure 5As shown, multiple groups of first through holes 1a are arranged in the first doping region 1, and multiple groups of second through holes 2a are arranged in the second doping region 2. The multiple groups of first through holes 1a and the multiple groups of second through holes 2a are arranged alternately. That is, one group of second through holes 2a is arranged between any two adjacent groups of first through holes 1a, and one group of first through holes 1a is arranged between any two adjacent groups of second through holes 2a. Figure 5 In the middle Z region is a group of first through holes 1a. Multiple groups of first through holes 1a and multiple groups of second through holes 2a are arranged in sequence along the length direction or width direction of the back contact battery. Among them, the number of columns of first through holes 1a included in each group of first through holes 1a is greater than the number of columns of second through holes 2a included in each group of second through holes 2a. Exemplarily, each group of first through holes 1a includes two, three or more columns of first through holes 1a, and each group of second through holes 2a includes one, two, three or more columns of second through holes 2a. The number of columns of first through holes 1a included in each group of first through holes 1a is greater than the number of columns of second through holes 2a included in each group of second through holes 2a. This makes it easier to make the total number of first through holes 1a greater than the total number of second through holes 2a, and it is easier to achieve that the total area of ​​all first through holes 1a opened in the passivation layer C is greater than the total area of ​​all second through holes 2a.

[0055] In the above embodiment, in order to simplify the processing technology, each group of first through holes 1a may include two columns of first through holes 1a, and the two columns of first through holes 1a in each group may be staggered. Compared with the alignment of the two columns of first through holes 1a in each group, the staggered arrangement of the two columns of first through holes 1a in each group can further ensure the uniformity of current extraction. In this embodiment, each group of second through holes 2a includes one column of second through holes 2a to further simplify the process.

[0056] Further, the first through holes 1a and the second through holes 2a have the same shape and size, and each group of first through holes 1a includes two columns of first through holes 1a, and each group of second through holes 2a includes one column of second through holes 2a, and the spacing between the centers of adjacent first through holes 1a in the same column is equal to the spacing between the centers of adjacent second through holes 2a in the same column. In this embodiment, the shapes of the first through holes 1a and the second through holes 2a can both be elliptical holes, circular holes or square holes, and the sizes of the first through holes 1a and the second through holes 2a are the same, that is, the areas of a single first through hole 1a and a single second through hole 2a are the same. The number of columns of the first through holes 1a is twice the number of columns of the second through holes 2a, and the spacing between the centers of adjacent first through holes 1a in the same column is equal to the spacing between the centers of adjacent second through holes 2a in the same column, so as to ensure that the number of first through holes 1a is twice the number of second through holes 2a, thereby ensuring that the total area of ​​all first through holes 1a opened in the passivation layer C is greater than the total area of ​​all second through holes 2a. In this embodiment, the spacing between the centers of adjacent first through holes 1a in the same column and the spacing between the centers of adjacent second through holes 2a in the same column L3 may be 25 μm-45 μm, specifically 25 μm, 30 μm, 35 μm, 40 μm or 45 μm.

[0057] like Figure 6 As shown, the area of ​​a single first through hole 1a is greater than the area of ​​a single second through hole 2a, wherein the shapes of the first through hole 1a and the second through hole 2a may be the same or different. The number of first through holes 1a is greater than or less than the number of second through holes 2a, and the number of first through holes 1a and second through holes 2a may be set according to actual conditions. In this embodiment, the spacing L4 between the centers of adjacent first through holes 1a in the same column may be 80μm-120μm, specifically 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm or 120μm. The spacing L5 between the centers of adjacent first through holes 1a in the same column may be 60μm-80μm, specifically 60μm, 65μm, 70μm, 75μm or 80μm. In addition, in this solution, the first through hole 1a and the second through hole 2a can both be square holes, and the side length of the first through hole 1a can be 35μm-45μm, specifically 35μm, 38μm, 40μm, 42μm or 45μm. The side length of the second through hole 2a can be 15μm-25μm, specifically 15μm, 18μm, 20μm, 22μm or 25μm.

[0058] Alternatively, the area of ​​a single first through hole 1a may be smaller than the area of ​​a single second through hole 2a, and the number of first through holes 1a may be greater than the number of second through holes 2a. In short, it is sufficient to ensure that the total area of ​​all first through holes 1a opened in the passivation layer C is greater than the total area of ​​all second through holes 2a. The specific setting can be made according to the complexity of the process and the uniformity of current distribution.

[0059] like Figure 7 As shown, the shapes of the first through hole 1a and the second through hole 2a are different, the area of ​​a single first through hole 1a is greater than the area of ​​a single second through hole 2a, and the spacing between the centers of adjacent first through holes 1a in the same column is equal to the spacing between the centers of adjacent second through holes 2a in the same column. The spacing between the centers of adjacent first through holes 1a in the same column and the spacing L6 between the centers of adjacent second through holes 2a in the same column can be 25μm-45μm, specifically 25μm, 30μm, 35μm, 40μm or 45μm. Exemplarily, the first through hole 1a is a square hole, and the side length L7 of the first through hole 1a is 10μm-20μm, specifically 10μm, 12μm, 15μm, 18μm or 20μm. The second through hole 2a is a circular hole, and the diameter of the second through hole 2a is 10μm-20μm, specifically 10μm, 12μm, 15μm, 18μm or 20μm. Of course, the first through hole 1a and the second through hole 2a may also be any other shapes, which are not limited here.

[0060] In any of the above embodiments, the first through hole 1a and / or the second through hole 2a include a circular hole, an elliptical hole and / or a polygonal hole, wherein the polygonal hole may include a square hole, a triangular hole, a pentagonal hole, etc. In this way, the first through hole 1a and / or the second through hole 2a have a regular shape and are easy to process and manufacture. Among them, the diameter of the circular hole is 10μm to 45μm, and preferably the diameter of the circular hole is 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 25μm, 28μm, 30μm, 32μm, 35μm, 38μm, 40μm or 45μm. The side length of the square hole is 10μm to 45μm, and the preferred side length of the square hole is 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 25μm, 28μm, 30μm, 32μm, 35μm, 38μm, 40μm or 45μm.

[0061] In the same column of first through holes 1a, the spacing between the centers of adjacent first through holes 1a is 25 μm to 110 μm to accommodate back contact batteries of different sizes. Exemplarily, the spacing between the centers of adjacent first through holes 1a in the same column is 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm or 110 μm.

[0062] In the same column of second through holes 2a, the spacing between the centers of adjacent second through holes 2a is 25 μm to 110 μm to accommodate back contact batteries of different sizes. Exemplarily, the spacing between the centers of adjacent second through holes 2a in the same column is 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm or 110 μm.

[0063] The first through holes 1a in the same column may be evenly distributed or unevenly distributed, and the second through holes 2a in the same column may be evenly distributed or unevenly distributed, which may be set according to actual conditions.

[0064] In a specific embodiment, the first doping region 1 and the second doping region 2 are alternately distributed in a forked finger shape, so that the first electrode and the second electrode have no overlapping area in the vertical direction of the battery, avoiding the possibility of leakage current in space. In this embodiment, each column of first through holes 1a can include multiple grouped first through holes 1a, and the second doping region passes between two adjacent grouped first through holes 1a, and the first doping region 1 passes between multiple first through holes 1a in the same group, and no second doping region 2 passes through; each column of second through holes 2a can include multiple grouped second through holes 2a, and the first doping region 1 passes between two adjacent grouped second through holes 2a, and the second doping region 2 passes between multiple second through holes 2a in the same group, and no first doping region 1 passes through. Of course, the first doping region 1 and the second doping region 2 can also be distributed at intervals along the length direction or width direction of the battery, which is not limited here.

[0065] In the above-mentioned embodiments, the adjacent first through holes 1a in the spacing between the centers of adjacent first through holes 1a in the same column refer to two first through holes 1a between which the first doping region 1 passes and no second doping region 2 passes. Similarly, the adjacent second through holes 2a in the spacing between the centers of adjacent second through holes 2a in the same column refer to two second through holes 2a between which the second doping region 2 passes and no first doping region 1 passes.

[0066] In addition, the embodiment of the present application further provides a photovoltaic module, which includes the back contact cell provided by any of the above embodiments. Compared with the prior art, the beneficial effects of the photovoltaic module provided by the embodiment of the present application are the same as the beneficial effects of the above back contact cell, which will not be repeated here.

[0067] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0068] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A back contact battery, characterized in that: The substrate includes a substrate, a back doping layer, a passivation layer and an electrode from top to bottom along the thickness direction of the substrate, wherein: The back doped layer includes a first doped region and a second doped region, and the first doped region and the second doped region have opposite conductivity types; a plurality of first through holes are opened in the region of the passivation layer corresponding to the first doped region, and a plurality of second through holes are opened in the region of the passivation layer corresponding to the second doped region; the electrode includes a first electrode and a second electrode, the first electrode passes through the first through hole to be in conductive contact with the first doped region, and the second electrode passes through the second through hole to be in conductive contact with the second doped region; The total area of ​​all first through holes formed in the passivation layer is greater than the total area of ​​all second through holes; The first through hole and the second through hole have the same shape and the same size, and the number of the first through holes is greater than the number of the second through holes; or, the first through hole and the second through hole have different shapes; or, the first through hole and the second through hole have the same shape and different sizes, and the number of the first through hole is different from the number of the second through holes.

2. The back contact cell according to claim 1, characterized in that: The first doped region is a P-type doped region, the second doped region is an N-type doped region, and the number of columns of first through holes opened in the first doped region is the same as the number of columns of second through holes opened in the second doped region; The number of columns of the first through holes and the number of columns of the second through holes are greater than or equal to 2, and one column of the second through holes is arranged between two adjacent columns of the first through holes, and one column of the first through holes is arranged between two adjacent columns of the second through holes.

3. The back contact battery according to claim 2, characterized in that: The first through holes and the second through holes have the same shape and size, and the spacing between the centers of adjacent first through holes in the same column is smaller than the spacing between the centers of adjacent second through holes in the same column.

4. The back contact cell according to claim 1, characterized in that: The first doped region is a P-type doped region, the second doped region is an N-type doped region, a plurality of groups of first through holes are arranged in the first doped region, a plurality of groups of second through holes are arranged in the second doped region, a group of second through holes is arranged between two adjacent groups of first through holes, and a group of first through holes is arranged between two adjacent groups of second through holes; The number of columns of first through holes included in each group of first through holes is greater than the number of columns of second through holes included in each group of second through holes.

5. The back contact cell according to claim 4, characterized in that: Each group of the first through holes includes two columns of first through holes, and the two columns of first through holes in each group are staggered.

6. The back contact cell according to claim 4 or 5, characterized in that: The first through holes and the second through holes have the same shape and size, and each group of first through holes includes two columns of first through holes, each group of second through holes includes one column of second through holes, and the spacing between the centers of adjacent first through holes in the same column is equal to the spacing between the centers of adjacent second through holes in the same column.

7. The back contact cell according to claim 1, characterized in that: The area of ​​a single first through hole is greater than the area of ​​a single second through hole, and the number of the first through holes is greater than or less than the number of the second through holes; or, The area of ​​a single first through hole is smaller than the area of ​​a single second through hole, and the number of the first through holes is greater than the number of the second through holes.

8. The back contact cell according to claim 1, characterized in that The first through hole and the second through hole have different shapes, the area of ​​a single first through hole is larger than the area of ​​a single second through hole, and the spacing between the centers of adjacent first through holes in the same column is equal to the spacing between the centers of adjacent second through holes in the same column.

9. The back contact cell according to any one of claims 1 to 5 or 7, characterized in that: The distance between the centers of adjacent first through holes in the same column is 25 μm to 110 μm; and / or, The distance between the centers of adjacent second through holes in the same column is 25 μm to 110 μm.

10. The back contact cell according to any one of claims 1 to 5 or 7, characterized in that: The first through hole and / or the second through hole comprises a circular hole, an elliptical hole and / or a polygonal hole; The diameter of the circular hole is 10 μm to 45 μm; or the polygonal hole includes a square hole, and the side length of the square hole is 10 μm to 45 μm.

11. The back contact cell according to any one of claims 1 to 5 or 7, characterized in that: The first doped regions and the second doped regions are alternately distributed in an interdigitated manner.

12. A photovoltaic module, characterized in that: Comprising a back contact cell as described in any one of claims 1-11.

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