Solar cell, cell assembly and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides a solar cell, a cell assembly and a photovoltaic system, and the solar cell comprises a silicon substrate which comprises an N region and a P region, and the N region and the P region are located at the same surface or two opposite surfaces of the silicon substrate; the N-type doped polycrystalline silicon layer is arranged on the N region; the P-type doped polycrystalline silicon layer is arranged on the P region; the first passivation layer is provided with a plurality of first through holes; the second passivation layer is provided with a plurality of second through holes; the first electrode penetrates through the plurality of first through holes and is in contact with the N-type doped polycrystalline silicon layer; the second electrode penetrates through the plurality of second through holes and is in contact with the P-type doped polycrystalline silicon layer; the contact area of the second electrode and the P-type doped polycrystalline silicon layer is larger than the contact area of the first electrode and the N-type doped polycrystalline silicon layer. According to the solar cell, the bonding tension between the P-type doped polycrystalline silicon layer and the second electrode can be increased, the reliability of the cell structure can be improved, the conductive effect of the P region can be improved, and the conversion efficiency of the cell can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of solar cells, in particular to a solar cell, a battery assembly and a photovoltaic system. Background Art

[0002] Solar cells can convert sunlight into electrical energy by using the photovoltaic effect of semiconductors. Solar cells mainly include bifacial solar cells and back-contact solar cells. Among them, the back-contact solar cell has both positive and negative electrodes designed on the back of the cell. Compared with bifacial solar cells, the front surface of the back-contact solar cell completely avoids the shading of metal grid lines, eliminating the optical loss caused by the shading of metal grid lines, which can greatly improve the cell conversion efficiency.

[0003] In the prior art, an N-type doped polysilicon layer is arranged on one side of the silicon substrate of a bifacial solar cell, and a P-type doped polysilicon layer is arranged on the other side of the silicon substrate, the first electrode of the bifacial solar cell contacts the N-type doped polysilicon layer, and the second electrode of the bifacial solar cell contacts the P-type doped polysilicon layer; an N-type doped polysilicon layer and a P-type doped polysilicon layer are alternately arranged on the back side of the silicon substrate of a back contact solar cell, the first electrode of the back contact solar cell contacts the N-type doped polysilicon layer, and the second electrode of the back contact solar cell contacts the P-type doped polysilicon layer. Since conventional solar cells usually do not consider the relationship between the contact area between the first electrode and the N-type doped polysilicon layer and the contact area between the second P electrode and the P-type doped polysilicon layer, especially for electrodes prepared by electroplating process, the contact area between the P-type doped polysilicon layer and the electrode is generally small, resulting in poor conductivity of the P region, thereby affecting the battery efficiency; moreover, the bonding tension between the P-type doped polysilicon layer and the electrode is small, and the reliability of the battery structure is poor. Utility Model Content

[0004] The utility model provides a solar cell, aiming to solve the problem that the contact area between the P-type doped polysilicon layer and the electrode of the solar cell in the prior art is small, resulting in poor conductivity of the P region, affecting the cell efficiency, and poor reliability of the cell structure.

[0005] The utility model is implemented by providing a solar cell, comprising:

[0006] A silicon substrate, wherein the silicon substrate comprises at least one N region and at least one P region, wherein the N region and the P region are located on the same surface of the silicon substrate, or the N region and the P region are located on two opposite surfaces of the silicon substrate;

[0007] An N-type doped polysilicon layer is disposed on the N region;

[0008] A P-type doped polysilicon layer is disposed on the P region;

[0009] A first passivation layer located in the N region is provided on a side of the N-type doped polysilicon layer away from the silicon substrate, and a plurality of first through holes are provided through the first passivation layer along a thickness direction thereof;

[0010] A second passivation layer located in the P region is provided on a side of the P-type doped polysilicon layer away from the silicon substrate, and a plurality of second through holes are provided through the second passivation layer along the thickness direction thereof;

[0011] A first electrode disposed in the N region, the first electrode passing through a plurality of the first through holes and contacting the N-type doped polysilicon layer;

[0012] A second electrode disposed in the P region, the second electrode passing through a plurality of the second through holes and contacting the P-type doped polysilicon layer;

[0013] The contact area between the second electrode and the P-type doped polysilicon layer is greater than the contact area between the first electrode and the N-type doped polysilicon layer.

[0014] Preferably, the total area of ​​the second through holes per unit area is greater than the total area of ​​the first through holes per unit area.

[0015] Preferably, the area of ​​any one of the second through holes is larger than the area of ​​any one of the first through holes.

[0016] Preferably, the number of the second through holes per unit area is greater than the number of the first through holes per unit area.

[0017] Preferably, the ratio of the contact area between the second electrode and the P-type doped polysilicon layer to the contact area between the first electrode and the N-type doped polysilicon layer is 1 to 1.5, and is not equal to 1.

[0018] Preferably, the ratio of the contact area between the second electrode and the P-type doped polysilicon layer to the contact area between the first electrode and the N-type doped polysilicon layer is 1.01-1.2.

[0019] Preferably, a distance between two adjacent edges of the second through-holes in each of the P regions is smaller than a distance between two adjacent edges of the first through-holes in each of the N regions.

[0020] Preferably, the aperture of the first through hole in at least one of the N regions is not equal to the aperture of the first through hole in at least one of the N regions.

[0021] Preferably, the aperture of the second through hole in at least one of the P regions is not equal to the aperture of the second through hole in at least one of the P regions.

[0022] Preferably, the silicon substrate includes a first side and a second side opposite to the first side, and the distance between the edge of the first through hole in the N region near the first side and the first side is greater than the distance between the second through hole in the P region near the second side and the second side.

[0023] Preferably, a distance between at least two adjacent first through holes in the N regions is greater than a distance between two adjacent second through holes in the P regions.

[0024] Preferably, the solar cell includes at least a first N region, a second N region, and a third N region arranged in sequence, and a distance from an edge of the first through hole in the second N region to an edge of the first through hole in the first N region is not equal to a distance from an edge of the first through hole in the second N region to an edge of the first through hole in the third N region.

[0025] Preferably, the solar cell includes at least a first P zone, a second P zone and a third P zone arranged in sequence, and the distance from the edge of the second through hole in the second P zone to the edge of the second through hole in the first P zone is not equal to the distance from the edge of the second through hole in the second P zone to the edge of the second through hole in the third P zone.

[0026] Preferably, a region of the N-type doped polysilicon layer corresponding to a first through hole is provided with a plurality of first countersunk holes, a region of the P-type doped polysilicon layer corresponding to a second through hole is provided with a plurality of second countersunk holes, and the number of the second countersunk holes corresponding to each second through hole is greater than the number of the first countersunk holes corresponding to each first through hole.

[0027] Preferably, the aperture of the second countersunk hole is larger than the aperture of the first countersunk hole.

[0028] Preferably, the distribution density of the second countersunk holes is greater than the distribution density of the first countersunk holes.

[0029] Preferably, a depth at which the second electrode enters the P-type doped polysilicon layer is greater than a depth at which the first electrode enters the N-type doped polysilicon layer.

[0030] Preferably, the ratio of the depth of the second electrode penetrating into the P-type doped polysilicon layer to the depth of the first electrode penetrating into the N-type doped polysilicon layer is 1-2.

[0031] Preferably, the ratio of the depth of the second electrode penetrating into the P-type doped polysilicon layer to the depth of the first electrode penetrating into the N-type doped polysilicon layer is 1.01-1.5.

[0032] Preferably, the solar cell includes a plurality of the first electrodes and a plurality of the second electrodes, and a width of at least one of the second electrodes is not equal to a width of at least one of the first electrodes.

[0033] Preferably, the solar cell is a back-contact solar cell, and the N region and the P region are located on the same surface of the silicon substrate.

[0034] Preferably, the solar cell is a double-sided solar cell, and the N region and the P region are respectively located on two opposite sides of the silicon substrate.

[0035] The utility model also provides a battery assembly, comprising the above-mentioned solar cell.

[0036] The utility model also provides a photovoltaic system, comprising the above-mentioned battery assembly.

[0037] The utility model provides a solar cell with at least one N region and at least one P region, wherein an N-type doped polysilicon layer is arranged in the N region, and a P-type doped polysilicon layer is arranged in the P region, a plurality of first through holes are arranged in a first passivation layer on a side of the N-type doped polysilicon layer away from a silicon substrate, and a plurality of second through holes are arranged in a second passivation layer on a side of the P-type doped polysilicon layer away from the silicon substrate, a first electrode passes through the plurality of first through holes to contact the N-type doped polysilicon layer, and a second electrode passes through the plurality of second through holes to contact the P-type doped polysilicon layer, so that the opening area of ​​the second through holes can be increased, so that the contact area between the second electrode and the P-type doped polysilicon layer is greater than the contact area between the first electrode and the N-type doped polysilicon layer, thereby increasing the contact area between the second electrode and the P-type doped polysilicon layer, increasing the bonding tension between the P-type doped polysilicon layer and the second electrode, and improving the reliability of the battery structure; moreover, since the contact area between the second electrode and the P-type doped polysilicon layer is increased, the second electrode and the P-type doped polysilicon layer form a good ohmic contact, so that the conductive effect of the P region can be improved, thereby improving the battery conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A cross-sectional schematic diagram of a first solar cell provided in Example 1 of the utility model;

[0039] Figure 2 A cross-sectional schematic diagram of a partial structure of a first solar cell provided in Example 1 of the utility model;

[0040] Figure 3 A schematic diagram of the back side of a first solar cell provided in Example 1 of the utility model;

[0041] Figure 4 A schematic diagram of the back side of the second solar cell provided in the first embodiment of the utility model;

[0042] Figure 5 A schematic diagram of the back side of a third solar cell provided in the first embodiment of the utility model;

[0043] Figure 6 A schematic diagram of the back side of a fourth solar cell provided in the first embodiment of the utility model;

[0044] Figure 7 A schematic diagram of the back side of the fifth solar cell provided in the first embodiment of the utility model;

[0045] Figure 8 A schematic diagram of a first through hole and a first countersunk hole of a solar cell provided in Embodiment 1 of the utility model;

[0046] Fig. 9 A schematic diagram of a second through hole and a second countersunk hole of a solar cell provided in Embodiment 1 of the utility model;

[0047] Fig.10 A cross-sectional schematic diagram of a solar cell provided in Embodiment 2 of the present utility model;

[0048] Fig.11 A front view schematic diagram of a solar cell provided in the second embodiment of the utility model;

[0049] Fig.12 This is a schematic diagram of the back side of a solar cell provided in Embodiment 2 of the present utility model. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0051] A solar cell provided by an embodiment of the utility model is provided with at least one N region and at least one P region, an N-type doped polysilicon layer is provided in the N region, a P-type doped polysilicon layer is provided in the P region, a plurality of first through holes are provided in a first passivation layer on a side of the N-type doped polysilicon layer facing away from a silicon substrate, a plurality of second through holes are provided in a second passivation layer on a side of the P-type doped polysilicon layer facing away from a silicon substrate, a first electrode passes through the plurality of first through holes to contact the N-type doped polysilicon layer, and a second electrode passes through the plurality of second through holes to contact the P-type doped polysilicon layer, so that the opening area of ​​the second through holes can be increased, so that the contact area between the second electrode and the P-type doped polysilicon layer is greater than the contact area between the first electrode and the N-type doped polysilicon layer, thereby increasing the contact area between the second electrode and the P-type doped polysilicon layer, increasing the bonding tension between the P-type doped polysilicon layer and the second electrode, and improving the reliability of the battery structure; moreover, since the contact area between the second electrode and the P-type doped polysilicon layer is increased, the second electrode and the P-type doped polysilicon layer form a good ohmic contact, so that the conductive effect of the P region can be improved, thereby improving the battery conversion efficiency.

[0052] Embodiment 1

[0053] Please refer to Figure 1-Figure 7 , a solar cell provided by an embodiment of the utility model comprises:

[0054] A silicon substrate 1, wherein the silicon substrate 1 comprises at least one N region 11 and at least one P region 12, wherein the N region 11 and the P region 12 are located on the same surface of the silicon substrate 1;

[0055] An N-type doped polysilicon layer 2 is disposed on the N region 11;

[0056] A P-type doped polysilicon layer 3 is disposed on the P region 12;

[0057] The first passivation layer 4 located in the N region 11 is disposed on a side of the N-type doped polysilicon layer 2 away from the silicon substrate 1, and a plurality of first through holes 41 are disposed through the first passivation layer 4 along the thickness direction thereof;

[0058] The second passivation layer 5 located in the P region 12 is disposed on the side of the P-type doped polysilicon layer 3 away from the silicon substrate 1, and a plurality of second through holes 51 are disposed through the second passivation layer 5 along the thickness direction thereof;

[0059] A first electrode 6 disposed in the N region 11, the first electrode 6 passes through a plurality of first through holes 41 and contacts the N-type doped polysilicon layer 2;

[0060] A second electrode 7 disposed in the P region 12, the second electrode 7 passes through a plurality of second through holes 51 and contacts the P-type doped polysilicon layer 3;

[0061] The contact area between the second electrode 7 and the P-type doped polysilicon layer 3 is larger than the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 .

[0062] A solar cell provided by an embodiment of the utility model is provided with a plurality of first through holes 41 in a first passivation layer 4 on a side of an N-type doped polysilicon layer 2 facing away from a silicon substrate 1, and a plurality of second through holes 51 in a second passivation layer 5 on a side of a P-type doped polysilicon layer 3 facing away from the silicon substrate 1, a first electrode 6 passes through the plurality of first through holes 41 to contact the N-type doped polysilicon layer 2, and a second electrode 7 passes through the plurality of second through holes 51 to contact the P-type doped polysilicon layer 3. By increasing the opening area of ​​the second through hole 51, the second electrode 7 can contact and conduct with the P-type doped polysilicon layer 3 through the second through hole 51 with more opening area, so that the contact area of ​​the P-type doped polysilicon layer 3 is larger than the contact area of ​​the first electrode 6 and the N-type doped polysilicon layer 2. Compared with the contact area between the first electrode 6 and the N-type doped polysilicon layer 2, the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 is increased, thereby increasing the bonding tension between the P-type doped polysilicon layer 3 and the second electrode 7, and the connection between the second electrode 7 and the P-type doped polysilicon layer 3 is more stable and reliable, which can improve the reliability of the battery structure and the mechanical stability of the battery; moreover, due to the increase in the contact area between the second electrode 7 and the P-type doped polysilicon layer 3, the second electrode 7 and the P-type doped polysilicon layer 3 form a better ohmic contact, improve the conductivity of the second electrode 7 and the P-type doped polysilicon layer 3, improve the conductivity of the second electrode 7 and the P-type doped polysilicon layer 3, improve the conductivity of the P region 12, balance the conductivity of the N region 11 and the P region 12, and improve the conversion efficiency of the solar cell.

[0063] In the embodiment of the utility model, the first through hole 41 and the second through hole 51 can be formed by laser drilling or other processes. The first through hole 41 and the second through hole 51 are arranged to facilitate the preparation of the first electrode 6 and the second electrode 7 by electroplating process.

[0064] In the embodiment of the utility model, the solar cell is a back contact solar cell, the solar cell comprises a light-facing surface 101 and a backlight surface 102 opposite to the light-facing surface 101 , and the N region 11 and the P region 12 are both located on the backlight surface 102 of the solar cell.

[0065] In the embodiment of the utility model, there are multiple N regions 11 and P regions 12, and the N regions 11 and P regions 12 are alternately arranged on the backlight surface 102. Among them, an isolation region 13 for isolating the N region 11 and the P region 12 is arranged between adjacent N regions 11 and P regions 12, and the isolation region 13 can be a groove.

[0066] In the embodiment of the utility model, the specific number of the first through holes 41 in each N region 11 is not limited, and the first through holes 41 in the N region 11 can be arranged in one column or multiple columns and multiple rows; the specific number of the second through holes 51 in each P region 12 is also not limited, and the second through holes 51 in the P region 12 can also be arranged in one column or multiple columns and multiple rows.

[0067] The sizes and shapes of all the first through holes 41 in each N region 11 may be the same or different; the sizes and shapes of all the second through holes 51 in each P region 12 may be the same or different. Figure 3 It is shown that the number of the first through holes 41 in each N region 11 is 5 and arranged in a row; the number of the second through holes 51 in each P region 12 is 5 and arranged in a row; Figure 3 The first through hole 41 and the second through hole 51 shown are both circular through holes, and the diameter of the second through hole 51 is greater than the diameter of the first through hole 41 .

[0068] As an embodiment of the present invention, the solar cell further includes a first tunneling layer 8 disposed between the N-type doped polysilicon layer 2 and the surface of the silicon substrate 1 , and a second tunneling layer 9 disposed between the P-type doped polysilicon layer 3 and the surface of the silicon substrate 1 .

[0069] In this embodiment, the first tunneling layer 8 and the second tunneling layer 9 may be silicon oxide layers. The cell efficiency of the solar cell may be further improved by utilizing the tunneling passivation effect of the first tunneling layer 8 and the second tunneling layer 9 .

[0070] As an embodiment of the present invention, the total area of ​​the second through holes 51 per unit area is greater than the total area of ​​the first through holes 41 per unit area.

[0071] The unit area may be the total area of ​​the entire solar cell or a partial area of ​​the solar cell. It can be understood that, under the premise of the same unit area, the sum of the areas of all the second through holes 51 in the unit area is greater than the sum of the areas of all the first through holes 41 in the unit area, that is, compared with the first electrode 6, the second electrode 7 can contact the P-type doped polysilicon layer 3 through the second through holes 51 with a larger total area, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3, thereby improving the bonding tension and conductive effect between the second electrode 7 and the P-type doped polysilicon layer 3. In the embodiment of the utility model, the area of ​​the first through hole 41 is the area of ​​the cross section of the first through hole 41; the area of ​​the second through hole 51 is the area of ​​the cross section of the second through hole 51.

[0072] In the embodiment of the utility model, the first electrode 6 and the second electrode 7 can be prepared by screen printing or electroplating process, the slurry of the first electrode 6 is filled into the first through hole 41 and contacts the N-type doped polysilicon layer 2, and the slurry of the second electrode 7 is filled into the second through hole 51 and contacts the P-type doped polysilicon layer 3. Since the sum of the areas of all the second through holes 51 in a unit area is greater than the sum of the areas of all the first through holes 41 in a unit area, more slurry of the second electrode 7 can contact the P-type doped polysilicon layer 3 through the second through hole 51, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0073] In the embodiment of the utility model, the second through hole 51 and the first through hole 41 can be a circular through hole, a square through hole, an elliptical hole, a polygonal through hole or an irregular through hole.

[0074] like Figure 3 As shown, as an embodiment of the present invention, the area of ​​any second through hole 51 is greater than the area of ​​any first through hole 41 .

[0075] In this embodiment, the shapes of the second through hole 51 and the first through hole 41 may be the same or different. Among them, since the area of ​​any second through hole 51 is larger than the area of ​​any first through hole 41, the contact area between the P-type doped polysilicon layer 3 of any P region 12 and the second electrode 7 can be larger than the contact area between the N-type doped polysilicon layer 2 of any N region 11 and the first electrode 6, and the conductive effect and bonding tension between each second electrode 7 and the P-type doped polysilicon layer 3 can be improved. For example, when the second through hole 51 and the first through hole 41 are both circular through holes, the diameter of the second through hole 51 is larger than the diameter of the first through hole 41, so that the area of ​​any second through hole 51 is larger than the area of ​​any first through hole 41; when the second through hole 51 and the first through hole 41 are both irregular through holes, it is only necessary to satisfy that the sum of the areas of all the second through holes 51 in a unit area is larger than the sum of the areas of all the first through holes 41 in a unit area.

[0076] Please refer to Figure 4 As an embodiment of the present invention, the number of the second through holes 51 per unit area is greater than the number of the first through holes 41 per unit area.

[0077] In this embodiment, under the premise of the same unit area, the number of all second through holes 51 within the unit area is greater than the number of all first through holes 41 within the unit area, so that the distribution density of the second through holes 51 is greater than the distribution density of the first through holes 41. Compared with the first electrode 6, the second electrode 7 can contact the P-type doped polysilicon layer 3 through a larger number of second through holes 51, thereby further increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0078] Among them, Figure 4 As shown in the figure, the number of the first through holes 41 in each N region 11 is 5, and the number of the second through holes 41 in each P region 12 is 9, so the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 can be further increased.

[0079] like Figure 4 As shown, as an optional embodiment of the utility model, the aperture of a single second through hole 51 is larger than the aperture of a single first through hole 41, and the number of second through holes 51 per unit area is larger than the number of first through holes 41 per unit area, which can increase the area of ​​each second through hole 51 and increase the number of second through holes 51, thereby further increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0080] like Figure 5 As shown, as an embodiment of the utility model, the aperture of the second through hole 51 of each N region 11 is greater than or equal to the aperture of the first through hole 41 of each P region 11; the center distance L2 of two adjacent second through holes 51 of each N region 11 is greater than the center distance L1 of two adjacent first through holes 41 of each P region 11, so that the distribution density of the first through holes 41 of the P region 11 within a unit area is denser, and the total area of ​​the second through holes 51 of each P region 11 can be made greater than the total area of ​​the first through holes 41 of each N region 11, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0081] As an optional embodiment of the utility model, the first through hole 41 and the second through hole 51 are both circular through holes, and the diameters of the first through hole 41 and the second through hole 51 are 18 to 22 um. For example, the diameters of the first through hole 41 and the second through hole 51 can be 20 um, the center spacing between two adjacent second through holes 51 in each P region 12 is 78 to 85 um, and the center spacing between two adjacent first through holes 41 in each N region 11 is 86 to 90 um. Of course, the sizes of the first through hole 41 and the second through hole 51 are not limited thereto, and can be flexibly set in practical applications.

[0082] As an embodiment of the present invention, the ratio of the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 to the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 is 1-1.5 and is not equal to 1.

[0083] In this embodiment, the ratio of the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 to the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 is 1-1.5, and is not equal to 1. It can be understood that the ratio of the total area of ​​the second through holes 51 per unit area to the total area of ​​the first through holes 41 per unit area is 1-1.5, and is not equal to 1. Among them, the ratio of the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 to the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 can be: 1.01, or 1.05, or 1.1, or 1.15, or 1.2, or 1.23, or 1.28, or 1.3, or 1.35, or 1.38, or 1.4, or 1.42, or 1.47, or 1.5.

[0084] In this embodiment, the ratio of the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 to the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 is set to 1 to 1.5, and is not equal to 1, so that the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 and the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 can have a more appropriate difference, and it is convenient to set the first through hole 41 and the second through hole 51.

[0085] As an embodiment of the utility model, the ratio of the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 to the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 is 1.01 to 1.2, which can further reduce the difference in contact area between the two, which is conducive to making the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 and the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 have a more appropriate difference.

[0086] like Figure 3 As shown, as an embodiment of the present invention, the distance d1 between the edges of two adjacent second through holes 51 in each P region 12 is smaller than the distance d2 between the edges of two adjacent first through holes 41 in each N region 11 .

[0087] In this embodiment, the distance d1 between the edges of adjacent second through holes 51 of each P region 12 is smaller than the distance d1 between the edges of two adjacent first through holes 41 of each N region 11. It can be understood that the second through holes 51 of the P region 12 occupy a larger area of ​​the P region 12. Compared with the first electrode 6, the second electrode 7 can contact the P-type doped polysilicon layer 3 through the second through holes 51 with a larger area, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3, thereby enhancing the bonding tension between the second electrode 7 and the P-type doped polysilicon layer 3.

[0088] Please refer to Figure 3As an embodiment of the present invention, at least a distance d4 between the first through holes 41 of two adjacent N regions 11 is greater than a distance d3 between the second through holes 51 corresponding to two adjacent P regions 12 .

[0089] It can be understood that, among all N regions 11 and all P regions 12, the distance between the first through holes 41 of at least two adjacent N regions 11 is greater than the distance between the second through holes 51 corresponding to two adjacent P regions 12, and the size of the second through hole 51 can be further increased, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0090] Please refer to Figure 6 As an embodiment of the utility model, the silicon substrate 1 includes a first side 15 and a second side 16 opposite to the first side 15, and a distance d9 between an edge of the first through hole 41 of the N region 11 close to the first side 15 and the first side 15 is greater than a distance d10 between the second through hole 51 of the P region 12 close to the second side 16 and the second side 16.

[0091] In the present embodiment, a distance d9 between the first through hole 41 corresponding to the N region 11 near the first side and the first side 15 is greater than a distance d10 between the second through hole 51 corresponding to the P region 12 near the second side and the second side 16. It can be understood that, compared with the N region 11 at the edge, the second through hole 51 located at the edge of the P region 12 occupies a larger area of ​​the P region 12 than the first through hole 41 located at the edge of the N region 11 occupies an area of ​​the N region 11. Therefore, the contact area between the second electrode 7 located at the edge and the P-type doped polysilicon layer 3 is increased, the bonding tension and conductive effect between the second electrode 7 located at the edge and the P-type doped polysilicon layer 3 are improved, and the reliability of the battery structure and the battery efficiency are improved.

[0092] As an embodiment of the present utility model, the ratio of the area of ​​all second through holes 51 in the P region 12 to the area of ​​the P region 12 is greater than the ratio of the area of ​​all first through holes 41 in the N region 11 to the area of ​​the N region 11, that is, the area ratio of the second through holes 51 in the P region 12 is greater than the area ratio of the first through holes 41 in the N region 11, which can further increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0093] Please refer to Figure 7 As an embodiment of the utility model, the solar cell includes at least a first N region 111, a second N region 112, and a third N region 113 which are arranged in sequence, and a distance d5 from an edge of the first through hole 41 of the second N region 112 to an edge of the first through hole 41 of the first N region 111 is not equal to a distance d6 from an edge of the first through hole 41 of the second N region 112 to an edge of the first through hole 41 of the third N region 113.

[0094] In this embodiment, the solar cell includes at least three N regions 11, that is, at least a first N region 111, a second N region 112, and a third N region 113. The distance d5 from the edge of the first through hole 41 of the second N region 112 to the edge of the first through hole 41 of the first N region 111 is not equal to the distance d6 from the edge of the first through hole 41 corresponding to the second N region 112 to the edge of the first through hole 41 corresponding to the third N region 113, so that the distance between the two groups of first through holes 41 corresponding to two adjacent groups of N regions 11 can be changed by adjusting the width of part of the N region 11 or adjusting the width of the isolation region 13, so that the width of the N region 11 and the spacing between adjacent N regions 11 are differentiated, which can improve the light absorption range and photoelectric conversion efficiency of the solar cell and maximize the use of light energy resources.

[0095] As an embodiment of the utility model, the solar cell includes at least a first P zone 121, a second P zone 122 and a third P zone 123 arranged in sequence, and the distance d7 from the edge of the second through hole 51 of the second P zone 122 to the edge of the second through hole 51 of the first P zone 121 is not equal to the distance d8 from the edge of the second through hole 51 of the second P zone 122 to the edge of the second through hole 51 of the third P zone 123.

[0096] In this embodiment, the solar cell includes at least three P regions 12, namely, at least a first P region 121, a second P region 122 and a third P region 123. The distance from the edge of the second through hole 51 of the second P region 12 to the edge of the second through hole 51 of the first P region 121 is not equal to the distance from the edge of the second through hole 51 of the second P region 122 to the edge of the second through hole 51 of the third P region 123. The width of the P region 12 and the distance between two adjacent P regions 12 can be differentiated by adjusting the width of part of the P region 12 or adjusting the width of the isolation region 13, which can improve the light absorption range and photoelectric conversion efficiency of the solar cell and maximize the use of light energy resources.

[0097] like Figure 7 As shown, by increasing the width of the isolation region 13 between the second P region 122 and the second N region 112, the distance between the second N region 112 and the third N region 113 can be made greater than the distance between the second N region 112 and the first N region 111, and at the same time, the distance between the second P region 122 and the third P region 123 can be made greater than the distance between the second P region 122 and the first P region 121, so that the width of the P region 12 and the distance between two adjacent P regions 12 are differentiated, and at the same time, the width of the N region 11 and the distance between adjacent N regions 11 are differentiated.

[0098] As an embodiment of the present invention, the aperture of the first through hole 41 of at least one N region 11 is not equal to the aperture of the first through hole 41 of at least one N region 11 .

[0099] In the present embodiment, the aperture of the first through hole 41 of at least one N region 11 is not equal to the aperture of the first through hole 41 corresponding to at least one other N region 11. It can be understood that, among the multiple N regions 11, the aperture of the first through hole 41 of at least one N region 11 is not equal to the aperture of the first through hole 41 of at least one N region 11 in the other N regions 11. In this way, the width of the first electrode 6 can be changed by adjusting the aperture of the first through hole 41 corresponding to at least one of the N regions 11, so that the width of at least one first electrode 6 is different from the width of other first electrodes 6, and the differentiated width design of the first electrode 6 can be realized, which can improve the light absorption range and photoelectric conversion efficiency of the solar cell and maximize the use of light energy resources.

[0100] As an embodiment of the present invention, the aperture of the second through hole 51 of at least one P region 12 is not equal to the aperture of the second through hole 51 of at least one P region 12 .

[0101] In the present embodiment, the aperture of the second through hole 51 of at least one P region 12 is not equal to the aperture of the second through hole 51 of at least one P region 12. It can be understood that, among the multiple P regions 12, the aperture of the second through hole 51 of at least one P region 12 is not equal to the aperture of the second through hole 51 of at least one P region 12 in the other P regions 12. The width of the second electrode 7 can be changed by adjusting the aperture of the second through hole 51 corresponding to at least one of the P regions 12. The width of at least one second electrode 7 can be made different from the width of other second electrodes 7. The differentiated width design of the second electrode 7 can be realized, which can further improve the light absorption range and photoelectric conversion efficiency of the solar cell and maximize the use of light energy resources.

[0102] As an embodiment of the present invention, the solar cell includes a plurality of first electrodes 6 and a plurality of second electrodes 7 , and the width of at least one of the second electrodes 7 is not equal to the width of at least one of the first electrodes 6 .

[0103] In this embodiment, a plurality of first electrodes 6 are respectively arranged in the N region 11, and a plurality of second electrodes 7 are respectively arranged in the P region 12. Among them, the width of at least one second electrode 7 is greater than the width of at least one first electrode 6, and the width of at least one second electrode 7 is less than the width of at least one first electrode 6, so that the width of the second electrode 7 is not consistent with the width of the first electrode 6, and the width difference between the first electrode 6 and the second electrode 7 can be flexibly adjusted instead of setting an electrode with a single width, which can improve the light absorption range and photoelectric conversion efficiency of the solar cell, and maximize the use of light energy resources, and greatly increase the probability of collecting photocurrent without affecting the production capacity.

[0104] In this embodiment, the width of the first electrode 6 can be adjusted by adjusting the aperture of the first through hole 41 corresponding to each first electrode 6, and the width of the second electrode 7 can be adjusted by adjusting the aperture of the second through hole 51 corresponding to each second electrode 7. This can achieve an optimized design of the widths of the first electrode 6 and the second electrode 7 and improve battery efficiency.

[0105] Please refer to Figure 8 and Fig. 9 As an embodiment of the utility model, a plurality of first countersunk holes 21 are arranged in an area of ​​the N-type doped polysilicon layer 2 corresponding to a first through hole 41, and a plurality of second countersunk holes 31 are arranged in an area of ​​the P-type doped polysilicon layer 3 corresponding to a second through hole 51, and the number of second countersunk holes 31 corresponding to a second through hole 51 is greater than the number of first countersunk holes 21 corresponding to a first through hole 41.

[0106] In this embodiment, by providing a plurality of first countersunk holes 21 in the region of the N-type doped polysilicon layer 2 corresponding to the first through hole 41, and providing a plurality of second countersunk holes 31 in the region of the P-type doped polysilicon layer 3 corresponding to a second through hole 51, the first electrode 6 enters the first through hole 41 and can enter the first countersunk hole 21 to contact the first countersunk hole 21, which can improve the contact effect between the first electrode 6 and the N-type doped polysilicon layer 2, and the second electrode 7 enters the second through hole 51 and can enter the second countersunk hole 31 to contact the second countersunk hole 31, which can improve the contact effect between the second electrode 7 and the P-type doped polysilicon layer 3; and, since the number of second countersunk holes 31 corresponding to one second through hole 51 is greater than the number of first countersunk holes 21 corresponding to one first through hole 41, the second electrode 7 can contact with a larger number of second countersunk holes 31, which can further increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3. Wherein, both the first countersunk hole 21 and the second countersunk hole 31 can be circular countersunk holes.

[0107] As an embodiment of the present invention, the diameter of the second counterbore 31 is larger than the diameter of the first counterbore 21 .

[0108] In this embodiment, since the aperture of the second countersunk hole 31 is larger than the aperture of the first countersunk hole 21 , the area of ​​each second countersunk hole 31 is larger than the area of ​​each first countersunk hole 21 , which can further increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 .

[0109] As an embodiment of the present invention, the distribution density of the second countersunk holes 31 is greater than the distribution density of the first countersunk holes 21 .

[0110] In this embodiment, the distribution density of the second countersunk holes 31 is greater than the distribution density of the first countersunk holes 21. It can be understood that the number of the second countersunk holes 31 per unit area is greater than the number of the first countersunk holes 21, so that the second electrode 7 can contact with more areas of the second countersunk holes 31, which can further increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3. In addition, the depth of the second countersunk holes 31 is greater than the depth of the first countersunk holes 21, which can further increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0111] As an embodiment of the present invention, the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 is greater than the depth of the first electrode 6 entering the N-type doped polysilicon layer 2 .

[0112] In this embodiment, after the slurry of the second electrode 7 passes through the second through hole 51, the slurry of the second electrode 7 can enter the P-type doped polysilicon layer 3, and after the slurry of the first electrode 6 passes through the first through hole 41, the slurry of the first electrode 6 can enter the N-type doped polysilicon layer 2, and the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 is greater than the depth of the first electrode 6 entering the N-type doped polysilicon layer 2, which can also increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0113] Among them, when the first electrode 6 and the second electrode 7 are prepared by the screen printing process, the slurry ratio of the second electrode 7 and the first electrode 6 can be adjusted so that the slurries of the second electrode 7 and the first electrode 6 have different burn-through capabilities, so that the burn-through capability of the slurry of the second electrode 7 is greater than the burn-through capability of the slurry of the first electrode 6, so that the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 is greater than the depth of the first electrode 6 entering the N-type doped polysilicon layer 2, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0114] As an embodiment of the present invention, the ratio of the depth of the second electrode 7 penetrating into the P-type doped polysilicon layer 3 to the depth of the first electrode 6 penetrating into the N-type doped polysilicon layer 2 is 1-2.

[0115] In this embodiment, the ratio of the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 to the depth of the first electrode 6 entering the N-type doped polysilicon layer 2 can be 1.0, or 1.01, or 1.20, or 1.35, or 1.55, or 1.60, or 1.80, or 1.90, or 2.0. Preferably, the ratio of the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 to the depth of the first electrode 6 entering the N-type doped polysilicon layer 2 is greater than 1, that is, the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 is greater than the depth of the first electrode 6 entering the N-type doped polysilicon layer 2.

[0116] As a preferred embodiment of the utility model, the ratio of the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 to the depth of the first electrode 6 entering the N-type doped polysilicon layer 2 is 1.01 to 1.5, which can reduce the difference between the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 and the depth of the first electrode 6 entering the N-type doped polysilicon layer 2, so that the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 and the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 have a more appropriate difference.

[0117] As an embodiment of the utility model, the first passivation layer 4 and the second passivation layer 5 are both at least one or a combination of aluminum oxide film layers, silicon oxide film layers, silicon nitride film layers, silicon carbide film layers, and silicon oxynitride film layers. For example, in some embodiments, the first passivation layer 4 and the second passivation layer 5 can both include aluminum oxide film layers and silicon nitride film layers stacked in sequence.

[0118] Embodiment 2

[0119] Please refer to Figure 10-12 , a solar cell provided by an embodiment of the utility model comprises:

[0120] A silicon substrate 1, wherein the silicon substrate 1 comprises at least one N region 11 and at least one P region 12, wherein the N region 11 and the P region 12 are respectively located on two opposite sides of the silicon substrate 1;

[0121] An N-type doped polysilicon layer 2 is disposed on the N region 11;

[0122] A P-type doped polysilicon layer 3 is disposed on the P region 12;

[0123] A first passivation layer 4 is provided on a side of the N-type doped polysilicon layer 2 facing away from the silicon substrate 1, and a plurality of first through holes 41 are provided through the first passivation layer 4 along the thickness direction thereof;

[0124] A second passivation layer 5 is provided on a side of the P-type doped polysilicon layer 3 facing away from the silicon substrate 1, and a plurality of second through holes 51 are provided through the second passivation layer 5 along the thickness direction thereof;

[0125] A first electrode 6 is disposed on the first passivation layer 4, and the first electrode 6 passes through a plurality of first through holes 41 and contacts the N-type doped polysilicon layer 2;

[0126] A second electrode 7 is disposed on the second passivation layer 5, and the second electrode 7 passes through a plurality of second through holes 51 and contacts the P-type doped polysilicon layer 3;

[0127] The contact area between the second electrode 7 and the P-type doped polysilicon layer 3 is larger than the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 .

[0128] The difference between the solar cell of this embodiment and the first embodiment is that the solar cell of this embodiment is a double-sided solar cell, the N region 11 and the P region 12 are respectively located on two opposite sides of the silicon substrate 1, and the other structures are the same as those of the first embodiment.

[0129] In the embodiment of the present invention, the solar cell comprises a first surface and a second surface opposite to the first surface; one of the first surface and the second surface is a light-facing surface 101 of the solar cell, and the other is a backlight surface 102 of the solar cell. Fig.10 The N regions 11 of the solar cell shown in the figure are arranged in sequence on the backlight surface 102 of the silicon substrate 1, and the P regions 12 are arranged in sequence on the light-facing surface 101 of the silicon substrate 1. Of course, the N regions 11 can also be arranged in sequence on the light-facing surface 101 of the silicon substrate 1, and the P regions 12 can be arranged in sequence on the backlight surface 102 of the silicon substrate 1.

[0130] In the embodiment of the utility model, there are multiple N regions 11 and P regions 12, and two adjacent N regions 11 are provided with a first isolation region 18, and two adjacent P regions 12 are provided with a second isolation region 19. Of course, the first isolation region 18 may not be provided between two adjacent N regions 11, and the second isolation region 19 may not be provided between two adjacent P regions 12.

[0131] A solar cell provided by an embodiment of the utility model is provided with a plurality of first through holes 41 in a first passivation layer 4 on a side of an N-type doped polysilicon layer 2 facing away from a silicon substrate 1, and a plurality of second through holes 51 in a second passivation layer 5 on a side of a P-type doped polysilicon layer 3 facing away from the silicon substrate 1, a first electrode 6 passes through the plurality of first through holes 41 to contact the N-type doped polysilicon layer 2, and a second electrode 7 passes through the plurality of second through holes 51 to contact the P-type doped polysilicon layer 3. By increasing the opening area of ​​the second through hole 51, the second electrode 7 can contact and conduct with the P-type doped polysilicon layer 3 through the second through hole 51 with more opening area, so that the contact area of ​​the P-type doped polysilicon layer 3 is larger than the contact area of ​​the first electrode 6 and the N-type doped polysilicon layer 2. Compared with the contact area between the first electrode 6 and the N-type doped polysilicon layer 2, the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 is increased, thereby increasing the bonding tension between the P-type doped polysilicon layer 3 and the second electrode 7, and the connection between the second electrode 7 and the P-type doped polysilicon layer 3 is more stable and reliable, which can improve the reliability of the battery structure and the mechanical stability of the battery; moreover, due to the increase in the contact area between the second electrode 7 and the P-type doped polysilicon layer 3, the second electrode 7 and the P-type doped polysilicon layer 3 form a better ohmic contact, improve the conductivity of the second electrode 7 and the P-type doped polysilicon layer 3, improve the conductivity of the second electrode 7 and the P-type doped polysilicon layer 3, improve the conductivity of the P region 12, balance the conductivity of the N region 11 and the P region 12, and improve the conversion efficiency of the solar cell.

[0132] As an embodiment of the present utility model, a first surface of a silicon substrate 1 is provided with a plurality of N regions 11 and a plurality of first isolation regions 18, and the N regions 11 and the first isolation regions 18 are alternately arranged in sequence; a second surface of the silicon substrate 1 has a plurality of P regions 12 and a plurality of second isolation regions 19, and the P regions 12 and the second isolation regions 19 are alternately arranged in sequence; an N-type doped polysilicon layer 2 is provided on the N region 11 and does not cover the first isolation region 18; a P-type doped polysilicon layer 3 is provided on the P region 12 and does not cover the second isolation region 19.

[0133] In this embodiment, the N-type doped polysilicon layer 2 only covers the N region 111 and does not cover the first isolation region 18, and the P-type doped polysilicon layer 3 only covers the P region 12 and does not cover the second isolation region 19. The first surface of the silicon substrate 1 is not completely covered by the N-type doped polysilicon layer 2, and the second surface of the silicon substrate 1 is not completely covered by the P-type doped polysilicon layer 3, which can effectively reduce the parasitic absorption of light by the N-type doped polysilicon layer 2 and the P-type doped polysilicon layer 3, thereby improving the conversion efficiency.

[0134] In some other embodiments, the N region 11 may also entirely cover the first surface, and the P region 12 may also entirely cover the second surface.

[0135] In the embodiment of the utility model, the specific number of the first through holes 41 in each N region 11 is not limited, and the first through holes 41 in the N region 11 can be arranged in one column or multiple columns and multiple rows; the specific number of the second through holes 51 in each P region 12 is also not limited, and the second through holes 51 in the P region 12 can also be arranged in one column or multiple columns and multiple rows.

[0136] The sizes and shapes of all the first through holes 41 in each N region 11 may be the same or different; the sizes and shapes of all the second through holes 51 in each P region 12 may be the same or different. Fig.11 It is shown that the number of the first through holes 41 in each P region 12 is 5 and arranged in a row; the number of the second through holes 51 in each N region 11 is 3 and arranged in a row; Fig.11 The first through hole 41 and the second through hole 51 shown are both circular through holes, and the diameter of the second through hole 51 is greater than the diameter of the first through hole 41 .

[0137] In the embodiment of the utility model, the first through hole 41 and the second through hole 51 can be formed by laser drilling or other processes. The first through hole 41 and the second through hole 51 are arranged to facilitate the preparation of the first electrode 6 and the second electrode 7 by electroplating process.

[0138] In the embodiment of the utility model, the specific number of the first through holes 41 in each N region 11 is not limited, and the first through holes 41 in the N region 11 can be arranged in one column or multiple columns and multiple rows; the specific number of the second through holes 51 in each P region 12 is also not limited, and the second through holes 51 in the P region 12 can also be arranged in one column or multiple columns and multiple rows.

[0139] The sizes and shapes of all the first through holes 41 in each N region 11 may be the same or different; the sizes and shapes of all the second through holes 51 in each P region 12 may be the same or different. Fig.11 It is shown that the number of first through holes 41 in each N region 11 is 3 and arranged in a row; the number of second through holes 51 in each P region 12 is 5 and arranged in a row; wherein the first through holes 41 and the second through holes 51 are both circular through holes, and the diameter of the second through holes 51 is greater than the diameter of the first through holes 41.

[0140] As an embodiment of the present invention, the solar cell further includes a first tunneling layer 8 disposed between the N-type doped polysilicon layer 2 and the surface of the silicon substrate 1 , and a second tunneling layer 9 disposed between the P-type doped polysilicon layer 3 and the surface of the silicon substrate 1 .

[0141] In this embodiment, the first tunneling layer 8 and the second tunneling layer 9 may be silicon oxide layers. The cell efficiency of the solar cell may be further improved by utilizing the tunneling passivation effect of the first tunneling layer 8 and the second tunneling layer 9 .

[0142] As an embodiment of the present invention, the total area of ​​the second through holes 51 per unit area is greater than the total area of ​​the first through holes 41 per unit area.

[0143] The unit area may be the total area of ​​the entire solar cell or a partial area of ​​the solar cell. It can be understood that, under the premise of the same unit area, the sum of the areas of all the second through holes 51 in the unit area is greater than the sum of the areas of all the first through holes 41 in the unit area, that is, compared with the first electrode 6, the second electrode 7 can contact the P-type doped polysilicon layer 3 through the second through holes 51 with a larger total area, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3, thereby improving the bonding tension and conductive effect between the second electrode 7 and the P-type doped polysilicon layer 3. In the embodiment of the utility model, the area of ​​the first through hole 41 is the area of ​​the cross section of the first through hole 41; the area of ​​the second through hole 51 is the area of ​​the cross section of the second through hole 51.

[0144] In the embodiment of the utility model, the first electrode 6 and the second electrode 7 can be prepared by screen printing or electroplating process, the slurry of the first electrode 6 is filled into the first through hole 41 and contacts the N-type doped polysilicon layer 2, and the slurry of the second electrode 7 is filled into the second through hole 51 and contacts the P-type doped polysilicon layer 3. Since the sum of the areas of all the second through holes 51 in a unit area is greater than the sum of the areas of all the first through holes 41 in a unit area, more slurry of the second electrode 7 can contact the P-type doped polysilicon layer 3 through the second through hole 51, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0145] In the embodiment of the utility model, the second through hole 51 and the first through hole 41 can be a circular through hole, a square through hole, an elliptical hole, a polygonal through hole or an irregular through hole.

[0146] As an embodiment of the present invention, the area of ​​any second through hole 51 is greater than the area of ​​any first through hole 41 .

[0147] In this embodiment, the shapes of the second through hole 51 and the first through hole 41 may be the same or different. Among them, since the area of ​​any second through hole 51 is larger than the area of ​​any first through hole 41, the contact area between the P-type doped polysilicon layer 3 of any P region 12 and the second electrode 7 can be larger than the contact area between the N-type doped polysilicon layer 2 of any N region 11 and the first electrode 6, and the conductive effect and bonding tension between each second electrode 7 and the P-type doped polysilicon layer 3 can be improved. For example, when the second through hole 51 and the first through hole 41 are both circular through holes, the diameter of the second through hole 51 is larger than the diameter of the first through hole 41, so that the area of ​​any second through hole 51 is larger than the area of ​​any first through hole 41; when the second through hole 51 and the first through hole 41 are both irregular through holes, it is only necessary to satisfy that the sum of the areas of all the second through holes 51 in a unit area is larger than the sum of the areas of all the first through holes 41 in a unit area.

[0148] As an embodiment of the present invention, the number of the second through holes 51 per unit area is greater than the number of the first through holes 41 per unit area.

[0149] In this embodiment, under the premise of the same unit area, the number of all second through holes 51 within the unit area is greater than the number of all first through holes 41 within the unit area, so that the distribution density of the second through holes 51 is greater than the distribution density of the first through holes 41. Compared with the first electrode 6, the second electrode 7 can contact the P-type doped polysilicon layer 3 through a larger number of second through holes 51, thereby further increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0150] As an optional embodiment of the present utility model, the aperture of a single second through hole 51 is larger than the aperture of a single first through hole 41, and the number of second through holes 51 per unit area is larger than the number of first through holes 41 per unit area, which can increase the area of ​​each second through hole 51 and increase the number of second through holes 51, thereby further increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0151] Similar to the first embodiment, as an embodiment of the present utility model, the aperture of the second through hole 51 of each N region 11 is greater than or equal to the aperture of the first through hole 41 of each P region 11; the center distance between two adjacent second through holes 51 of each N region 11 is greater than the center distance between two adjacent first through holes 41 of each P region 11, so that the distribution density of the first through holes 41 of the P region 11 within a unit area is denser, and the total area of ​​the second through holes 51 of each P region 11 can be made greater than the total area of ​​the first through holes 41 of each N region 11, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0152] As an optional embodiment of the utility model, the first through hole 41 and the second through hole 51 are both circular through holes, and the diameters of the first through hole 41 and the second through hole 51 are 18 to 22 um. For example, the diameters of the first through hole 41 and the second through hole 51 can be 20 um, the center spacing between two adjacent second through holes 51 in each P region 12 is 78 to 85 um, and the center spacing between two adjacent first through holes 41 in each N region 11 is 86 to 90 um. Of course, the sizes of the first through hole 41 and the second through hole 51 are not limited thereto, and can be flexibly set in practical applications.

[0153] As an embodiment of the present invention, the ratio of the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 to the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 is 1-1.5 and is not equal to 1.

[0154] In this embodiment, the ratio of the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 to the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 is 1-1.5, and is not equal to 1. It can be understood that the ratio of the total area of ​​the second through holes 51 per unit area to the total area of ​​the first through holes 41 per unit area is 1-1.5, and is not equal to 1. Among them, the ratio of the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 to the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 can be: 1.01, or 1.05, or 1.1, or 1.15, or 1.2, or 1.23, or 1.28, or 1.3, or 1.35, or 1.38, or 1.4, or 1.42, or 1.47, or 1.5.

[0155] In this embodiment, the ratio of the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 to the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 is set to 1 to 1.5, and is not equal to 1, so that the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 and the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 can have a more appropriate difference, and it is convenient to set the first through hole 41 and the second through hole 51.

[0156] As an embodiment of the utility model, the ratio of the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 to the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 is 1.01 to 1.2, which can further reduce the difference in contact area between the two, which is conducive to making the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 and the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 have a more appropriate difference.

[0157] like Fig.11 and Fig.12 As shown, as an embodiment of the present invention, the distance d1 between the edges of two adjacent second through holes 51 in each P region 12 is smaller than the distance d2 between the edges of two adjacent first through holes 41 in each N region 11 .

[0158] In this embodiment, the distance d1 between the edges of adjacent second through holes 51 of each P region 12 is smaller than the distance d1 between the edges of two adjacent first through holes 41 of each N region 11. It can be understood that the second through holes 51 of the P region 12 occupy a larger area of ​​the P region 12. Compared with the first electrode 6, the second electrode 7 can contact the P-type doped polysilicon layer 3 through the second through holes 51 with a larger area, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3, thereby enhancing the bonding tension between the second electrode 7 and the P-type doped polysilicon layer 3.

[0159] Similar to the first embodiment, as an embodiment of the present invention, the distance between the first through holes 41 of at least two adjacent N regions 11 is greater than the distance between the second through holes 51 corresponding to two adjacent P regions 12 .

[0160] It can be understood that, among all N regions 11 and all P regions 12, the distance between the first through holes 41 of at least two adjacent N regions 11 is greater than the distance between the second through holes 51 corresponding to two adjacent P regions 12, and the size of the second through hole 51 can be further increased, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0161] As an embodiment of the present utility model, the ratio of the area of ​​all second through holes 51 in the P region 12 to the area of ​​the P region 12 is greater than the ratio of the area of ​​all first through holes 41 in the N region 11 to the area of ​​the N region 11, that is, the area ratio of the second through holes 51 in the P region 12 is greater than the area ratio of the first through holes 41 in the N region 11, which can further increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0162] As an embodiment of the present invention, the aperture of the first through hole 41 of at least one N region 11 is not equal to the aperture of the first through hole 41 of at least one N region 11 .

[0163] In the present embodiment, the aperture of the first through hole 41 of at least one N region 11 is not equal to the aperture of the first through hole 41 corresponding to at least one other N region 11. It can be understood that, among the multiple N regions 11, the aperture of the first through hole 41 of at least one N region 11 is not equal to the aperture of the first through hole 41 of at least one N region 11 in the other N regions 11. In this way, the width of the first electrode 6 can be changed by adjusting the aperture of the first through hole 41 corresponding to at least one of the N regions 11, so that the width of at least one first electrode 6 is different from the width of other first electrodes 6, and the differentiated width design of the first electrode 6 can be realized, which can improve the light absorption range and photoelectric conversion efficiency of the solar cell and maximize the use of light energy resources.

[0164] As an embodiment of the present invention, the aperture of the second through hole 51 of at least one P region 12 is not equal to the aperture of the second through hole 51 of at least one P region 12 .

[0165] In the present embodiment, the aperture of the second through hole 51 of at least one P region 12 is not equal to the aperture of the second through hole 51 of at least one P region 12. It can be understood that, among the multiple P regions 12, the aperture of the second through hole 51 of at least one P region 12 is not equal to the aperture of the second through hole 51 of at least one P region 12 in the other P regions 12. The width of the second electrode 7 can be changed by adjusting the aperture of the second through hole 51 corresponding to at least one of the P regions 12. The width of at least one second electrode 7 can be made different from the width of other second electrodes 7. The differentiated width design of the second electrode 7 can be realized, which can further improve the light absorption range and photoelectric conversion efficiency of the solar cell and maximize the use of light energy resources.

[0166] As an embodiment of the present invention, the solar cell includes a plurality of first electrodes 6 and a plurality of second electrodes 7 , and the width of at least one of the second electrodes 7 is not equal to the width of at least one of the first electrodes 6 .

[0167] In this embodiment, a plurality of first electrodes 6 are respectively arranged in the N region 11, and a plurality of second electrodes 7 are respectively arranged in the P region 12. Among them, the width of at least one second electrode 7 is greater than the width of at least one first electrode 6, and the width of at least one second electrode 7 is less than the width of at least one first electrode 6, so that the width of the second electrode 7 is not consistent with the width of the first electrode 6, and the width difference between the first electrode 6 and the second electrode 7 can be flexibly adjusted instead of setting an electrode with a single width, which can improve the light absorption range and photoelectric conversion efficiency of the solar cell, and maximize the use of light energy resources, and greatly increase the probability of collecting photocurrent without affecting the production capacity.

[0168] In this embodiment, the width of the first electrode 6 can be adjusted by adjusting the aperture of the first through hole 41 corresponding to each first electrode 6, and the width of the second electrode 7 can be adjusted by adjusting the aperture of the second through hole 51 corresponding to each second electrode 7. This can achieve an optimized design of the widths of the first electrode 6 and the second electrode 7 and improve battery efficiency.

[0169] Similar to the first embodiment, reference may be made to Figure 8 and Fig. 9 As an embodiment of the utility model, a plurality of first countersunk holes 21 are arranged in an area of ​​the N-type doped polysilicon layer 2 corresponding to a first through hole 41, and a plurality of second countersunk holes 31 are arranged in an area of ​​the P-type doped polysilicon layer 3 corresponding to a second through hole 51, and the number of second countersunk holes 31 corresponding to a second through hole 51 is greater than the number of first countersunk holes 21 corresponding to a first through hole 41.

[0170] In this embodiment, by providing a plurality of first countersunk holes 21 in the region of the N-type doped polysilicon layer 2 corresponding to the first through hole 41, and providing a plurality of second countersunk holes 31 in the region of the P-type doped polysilicon layer 3 corresponding to a second through hole 51, the first electrode 6 enters the first through hole 41 and can enter the first countersunk hole 21 to contact the first countersunk hole 21, which can improve the contact effect between the first electrode 6 and the N-type doped polysilicon layer 2, and the second electrode 7 enters the second through hole 51 and can enter the second countersunk hole 31 to contact the second countersunk hole 31, which can improve the contact effect between the second electrode 7 and the P-type doped polysilicon layer 3; and, since the number of second countersunk holes 31 corresponding to one second through hole 51 is greater than the number of first countersunk holes 21 corresponding to one first through hole 41, the second electrode 7 can contact with a larger number of second countersunk holes 31, which can further increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3. Wherein, both the first countersunk hole 21 and the second countersunk hole 31 can be circular countersunk holes.

[0171] As an embodiment of the present invention, the diameter of the second counterbore 31 is larger than the diameter of the first counterbore 21 .

[0172] In this embodiment, since the aperture of the second countersunk hole 31 is larger than the aperture of the first countersunk hole 21 , the area of ​​each second countersunk hole 31 is larger than the area of ​​each first countersunk hole 21 , which can further increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 .

[0173] As an embodiment of the present invention, the distribution density of the second countersunk holes 31 is greater than the distribution density of the first countersunk holes 21 .

[0174] In this embodiment, the distribution density of the second countersunk holes 31 is greater than the distribution density of the first countersunk holes 21. It can be understood that the number of the second countersunk holes 31 per unit area is greater than the number of the first countersunk holes 21, so that the second electrode 7 can contact with more areas of the second countersunk holes 31, which can further increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3. In addition, the depth of the second countersunk holes 31 is greater than the depth of the first countersunk holes 21, which can further increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0175] As an embodiment of the present invention, the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 is greater than the depth of the first electrode 6 entering the N-type doped polysilicon layer 2 .

[0176] In this embodiment, after the slurry of the second electrode 7 passes through the second through hole 51, the slurry of the second electrode 7 can enter the P-type doped polysilicon layer 3, and after the slurry of the first electrode 6 passes through the first through hole 41, the slurry of the first electrode 6 can enter the N-type doped polysilicon layer 2, and the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 is greater than the depth of the first electrode 6 entering the N-type doped polysilicon layer 2, which can also increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0177] Among them, when the first electrode 6 and the second electrode 7 are prepared by the screen printing process, the slurry ratio of the second electrode 7 and the first electrode 6 can be adjusted so that the slurries of the second electrode 7 and the first electrode 6 have different burn-through capabilities, so that the burn-through capability of the slurry of the second electrode 7 is greater than the burn-through capability of the slurry of the first electrode 6, so that the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 is greater than the depth of the first electrode 6 entering the N-type doped polysilicon layer 2, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0178] As an embodiment of the present invention, the ratio of the depth of the second electrode 7 penetrating into the P-type doped polysilicon layer 3 to the depth of the first electrode 6 penetrating into the N-type doped polysilicon layer 2 is 1-2.

[0179] In this embodiment, the ratio of the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 to the depth of the first electrode 6 entering the N-type doped polysilicon layer 2 can be 1.0, or 1.01, or 1.20, or 1.35, or 1.55, or 1.60, or 1.80, or 1.90, or 2.0. Preferably, the ratio of the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 to the depth of the first electrode 6 entering the N-type doped polysilicon layer 2 is greater than 1, that is, the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 is greater than the depth of the first electrode 6 entering the N-type doped polysilicon layer 2.

[0180] As a preferred embodiment of the utility model, the ratio of the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 to the depth of the first electrode 6 entering the N-type doped polysilicon layer 2 is 1.01 to 1.5, which can reduce the difference between the depth of the second electrode 7 entering the P-type doped polysilicon layer 3 and the depth of the first electrode 6 entering the N-type doped polysilicon layer 2, so that the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 and the contact area between the first electrode 6 and the N-type doped polysilicon layer 2 have a more appropriate difference.

[0181] As an embodiment of the utility model, the first passivation layer 4 and the second passivation layer 5 are both at least one or a combination of aluminum oxide film layers, silicon oxide film layers, silicon nitride film layers, silicon carbide film layers, and silicon oxynitride film layers. For example, in some embodiments, the first passivation layer 4 and the second passivation layer 5 can both include aluminum oxide film layers and silicon nitride film layers stacked in sequence.

[0182] Embodiment 3

[0183] The present utility model also provides a battery assembly, which includes the solar cell of the above-mentioned embodiment 1 or embodiment 2. It should be noted that the battery assembly and the solar cell have the same or similar beneficial effects, and the relevant parts between the two can be referenced to each other. In order to avoid repetition, they will not be repeated here.

[0184] Embodiment 4

[0185] The present utility model also provides a photovoltaic system, which includes the battery assembly of the above-mentioned embodiment 3. It should be noted that the photovoltaic system has the same or similar beneficial effects as the solar cell, and the relevant parts between the two can be referenced to each other. In order to avoid repetition, it will not be repeated here.

[0186] A solar cell provided by an embodiment of the utility model is provided with at least one N region and at least one P region, an N-type doped polysilicon layer is provided in the N region, a P-type doped polysilicon layer is provided in the P region, a plurality of first through holes are provided in a first passivation layer on a side of the N-type doped polysilicon layer facing away from a silicon substrate, a plurality of second through holes are provided in a second passivation layer on a side of the P-type doped polysilicon layer facing away from a silicon substrate, a first electrode passes through the plurality of first through holes to contact the N-type doped polysilicon layer, and a second electrode passes through the plurality of second through holes to contact the P-type doped polysilicon layer, so that the opening area of ​​the second through holes can be increased, so that the contact area between the second electrode and the P-type doped polysilicon layer is greater than the contact area between the first electrode and the N-type doped polysilicon layer, thereby increasing the contact area between the second electrode and the P-type doped polysilicon layer, increasing the bonding tension between the P-type doped polysilicon layer and the second electrode, and improving the reliability of the battery structure; moreover, since the contact area between the second electrode and the P-type doped polysilicon layer is increased, the second electrode and the P-type doped polysilicon layer form a good ohmic contact, so that the conductive effect of the P region can be improved, thereby improving the battery conversion efficiency.

[0187] The above are only 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 in the protection scope of the present invention.

Claims

1. A solar cell, characterized in that: include: A silicon substrate, wherein the silicon substrate comprises at least one N region and at least one P region, wherein the N region and the P region are located on the same surface of the silicon substrate, or the N region and the P region are located on two opposite surfaces of the silicon substrate; An N-type doped polysilicon layer is disposed on the N region; A P-type doped polysilicon layer is disposed on the P region; A first passivation layer located in the N region is provided on a side of the N-type doped polysilicon layer away from the silicon substrate, and a plurality of first through holes are provided through the first passivation layer along a thickness direction thereof; A second passivation layer located in the P region is provided on a side of the P-type doped polysilicon layer away from the silicon substrate, and a plurality of second through holes are provided through the second passivation layer along the thickness direction thereof; A first electrode disposed in the N region, the first electrode passing through a plurality of the first through holes and contacting the N-type doped polysilicon layer; A second electrode disposed in the P region, the second electrode passing through a plurality of the second through holes and contacting the P-type doped polysilicon layer; The contact area between the second electrode and the P-type doped polysilicon layer is greater than the contact area between the first electrode and the N-type doped polysilicon layer.

2. The solar cell according to claim 1, characterized in that The total area of ​​the second through holes per unit area is greater than the total area of ​​the first through holes per unit area.

3. The solar cell according to claim 1, characterized in that An area of ​​any one of the second through holes is greater than an area of ​​any one of the first through holes.

4. The solar cell according to claim 1, characterized in that The number of the second through holes per unit area is greater than the number of the first through holes per unit area.

5. The solar cell according to claim 1, characterized in that: The ratio of the contact area between the second electrode and the P-type doped polysilicon layer to the contact area between the first electrode and the N-type doped polysilicon layer is 1 to 1.5 and is not equal to 1.

6. The solar cell according to claim 1, characterized in that The ratio of the contact area between the second electrode and the P-type doped polysilicon layer to the contact area between the first electrode and the N-type doped polysilicon layer is 1.01 to 1.

2.

7. The solar cell according to claim 1, characterized in that A distance between two adjacent edges of the second through-hole in each of the P regions is smaller than a distance between two adjacent edges of the first through-hole in each of the N regions.

8. The solar cell according to claim 1, characterized in that An aperture of the first through hole in at least one of the N regions is not equal to an aperture of the first through hole in at least one of the N regions.

9. The solar cell according to claim 1, characterized in that: The aperture of the second through hole of at least one of the P regions is not equal to the aperture of the second through hole of at least one of the P regions.

10. The solar cell according to claim 1, characterized in that The silicon substrate includes a first side and a second side opposite to the first side, and the distance between the edge of the first through hole in the N region near the first side and the first side is greater than the distance between the second through hole in the P region near the second side and the second side.

11. The solar cell according to claim 1, characterized in that: The distance between at least two adjacent first through holes in the N regions is greater than the distance between two adjacent second through holes in the P regions.

12. The solar cell according to claim 1, characterized in that The solar cell includes at least a first N region, a second N region, and a third N region arranged in sequence, and a distance from an edge of the first through hole in the second N region to an edge of the first through hole in the first N region is not equal to a distance from an edge of the first through hole in the second N region to an edge of the first through hole in the third N region.

13. The solar cell according to claim 1, characterized in that The solar cell includes at least a first P region, a second P region and a third P region arranged in sequence, and a distance from an edge of the second through hole in the second P region to an edge of the second through hole in the first P region is not equal to a distance from an edge of the second through hole in the second P region to an edge of the second through hole in the third P region.

14. The solar cell according to claim 1, characterized in that A plurality of first countersunk holes are arranged in an area of ​​the N-type doped polysilicon layer corresponding to a first through hole, and a plurality of second countersunk holes are arranged in an area of ​​the P-type doped polysilicon layer corresponding to a second through hole, and the number of the second countersunk holes corresponding to each second through hole is greater than the number of the first countersunk holes corresponding to each first through hole.

15. The solar cell according to claim 14, characterized in that: The aperture of the second counterbore is larger than the aperture of the first counterbore.

16. The solar cell according to claim 14, characterized in that: The distribution density of the second countersunk holes is greater than the distribution density of the first countersunk holes.

17. The solar cell according to claim 1, characterized in that A depth of the second electrode entering the P-type doped polysilicon layer is greater than a depth of the first electrode entering the N-type doped polysilicon layer.

18. The solar cell according to claim 1, characterized in that The ratio of the depth of the second electrode entering the P-type doped polysilicon layer to the depth of the first electrode entering the N-type doped polysilicon layer is 1-2.

19. The solar cell according to claim 1, characterized in that The ratio of the depth of the second electrode entering the P-type doped polysilicon layer to the depth of the first electrode entering the N-type doped polysilicon layer is 1.01 to 1.

5.

20. The solar cell according to claim 1, characterized in that The solar cell includes a plurality of the first electrodes and a plurality of the second electrodes, and a width of at least one of the second electrodes is not equal to a width of at least one of the first electrodes.

21. The solar cell according to claim 1, characterized in that The solar cell is a back contact solar cell, and the N region and the P region are located on the same surface of the silicon substrate.

22. The solar cell according to claim 1, characterized in that The solar cell is a double-sided solar cell, and the N region and the P region are respectively located on two opposite sides of the silicon substrate.

23. A battery assembly, characterized in that: Comprising the solar cell according to any one of claims 1 to 22.

24. A photovoltaic system, characterized in that: Comprising a battery assembly as claimed in claim 23.

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