Solar cell, cell assembly, and photovoltaic system

Abstract

The present disclosure is applicable to the technical field of solar cells. Provided are a solar cell, a cell assembly, and a photovoltaic system. The solar cell comprises: a silicon substrate, which comprises an N region and a P region, wherein the N region and the P region are located on the same surface or two opposite surfaces of the silicon substrate; an N-type doped polysilicon layer, which is arranged on the N region; a P-type doped polysilicon layer, which is arranged on the P region; a first passivation layer, which is provided with several first through holes; a second passivation layer, which is provided with several second through holes; a first electrode, which passes through the several first through holes to come into contact with the N-type doped polysilicon layer; and a second electrode, which passes through the several second through holes to come into contact with the P-type doped polysilicon layer, wherein the contact area of the second electrode and the P-type doped polysilicon layer is greater than that of the first electrode and the N-type doped polysilicon layer. The solar cell of the present disclosure can increase a bonding pull force between a P-type doped polysilicon layer and a second electrode, thereby improving the reliability of a cell structure; and the solar cell can also improve the conductive effect of a P region, thereby improving the conversion efficiency of the cell.

Description

A solar cell, a battery module and a photovoltaic system

[0001] Cross-reference to related applications

[0002] This disclosure claims priority to Chinese patent application No. 202410987826.5, filed on July 22, 2024, with the State Intellectual Property Office of China, entitled “A Solar Cell, Battery Module and Photovoltaic System”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of solar cell technology, specifically to a solar cell, a battery module, and a photovoltaic system. Background Technology

[0004] Solar cells utilize the photovoltaic effect of semiconductors to convert sunlight into electrical energy. Solar cells mainly include bifacial solar cells and back-contact solar cells. Back-contact solar cells, with both positive and negative electrodes located on the back of the cell, completely avoid the shading caused by metal grid lines on the front surface, thus eliminating optical losses and significantly improving cell conversion efficiency, compared to bifacial solar cells.

[0005] In existing technologies, bifacial solar cells have an N-type doped polycrystalline silicon layer on one side of the silicon substrate and a P-type doped polycrystalline silicon layer on the other side. The first electrode of the bifacial solar cell is in contact with the N-type doped polycrystalline silicon layer, and the second electrode is in contact with the P-type doped polycrystalline silicon layer. Back-contact solar cells have alternating N-type and P-type doped polycrystalline silicon layers on the back side of the silicon substrate. The first electrode of the back-contact solar cell is in contact with the N-type doped polycrystalline silicon layer, and the second electrode is in contact with the P-type doped polycrystalline silicon layer. Conventional solar cells typically do not consider the relationship between the contact area between the first electrode and the N-type doped polycrystalline silicon layer and the contact area between the second P-electrode and the P-type doped polycrystalline silicon layer. Especially for electrodes prepared using electroplating processes, the contact area between the P-type doped polycrystalline silicon layer and the electrode is generally small, resulting in poor conductivity in the P-region and thus affecting cell efficiency. Furthermore, this leads to weak bonding force between the P-type doped polycrystalline silicon layer and the electrode, resulting in poor cell structural reliability. Summary of the Invention

[0006] This disclosure provides a solar cell aimed at solving the problems of existing solar cells, such as the small contact area between the P-type doped polycrystalline silicon layer and the electrode, resulting in poor conductivity in the P-region, affecting cell efficiency, and poor cell structure reliability.

[0007] This disclosure is implemented by providing a solar cell comprising:

[0008] A silicon substrate, the silicon substrate comprising at least one N-region and at least one P-region, the N-region and the P-region being located on the same side of the silicon substrate, or the N-region and the P-region being located on opposite sides of the silicon substrate;

[0009] An N-type doped polycrystalline silicon layer is disposed on the N-region;

[0010] A P-type doped polysilicon layer is disposed on the P region;

[0011] The first passivation layer located in the N region is disposed on the side of the N-type doped polysilicon layer opposite to the silicon substrate, and a plurality of first vias penetrate the first passivation layer along the thickness direction of the first passivation layer.

[0012] The second passivation layer located in the P region is disposed on the side of the P-type doped polysilicon layer opposite to the silicon substrate, and a plurality of second vias penetrate the second passivation layer along the thickness direction of the second passivation layer;

[0013] A first electrode is disposed in the N region, and the first electrode passes through a plurality of first through holes to contact the N-type doped polysilicon layer;

[0014] A second electrode is provided in the P region, and the second electrode passes through a plurality of second through holes to contact the P-type doped polysilicon layer;

[0015] 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.

[0016] In some embodiments, the total area of ​​the second through hole per unit area is greater than the total area of ​​the first through hole per unit area.

[0017] In some embodiments, the area of ​​any one of the second through holes is greater than the area of ​​any one of the first through holes.

[0018] In some embodiments, the number of second through holes per unit area is greater than the number of first through holes per unit area.

[0019] In some embodiments, 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.

[0020] In some embodiments, 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.

[0021] In some embodiments, the spacing between the edges of two adjacent second through holes in each P region is less than the spacing between the edges of two adjacent first through holes in each N region.

[0022] In some embodiments, the diameters of the first through holes in at least two of the N regions are not equal.

[0023] In some embodiments, the diameters of the second through holes in at least two of the P regions are not equal.

[0024] In some embodiments, the silicon substrate includes a first side and a second side opposite to the first side, wherein the minimum distance between the edge of the first via in the N region near the first side and the first side is greater than the minimum distance between the second via in the P region near the second side and the second side.

[0025] In some embodiments, the minimum distance between the first through holes in at least two adjacent N regions is greater than the minimum distance between the second through holes in two adjacent P regions.

[0026] In some embodiments, the solar cell includes at least a first N region, a second N region, and a third N region arranged sequentially, wherein the minimum distance from the edge of the first through hole in the second N region to the edge of the first through hole in the first N region is not equal to the minimum distance from the edge of the first through hole in the second N region to the edge of the first through hole in the third N region.

[0027] In some embodiments, the solar cell includes at least a first P region, a second P region, and a third P region arranged sequentially, wherein the minimum distance from the edge of the second through hole in the second P region to the edge of the second through hole in the first P region is not equal to the minimum distance from the edge of the second through hole in the second P region to the edge of the second through hole in the third P region.

[0028] In some embodiments, the N-type doped polysilicon layer has a plurality of first countersunk holes in the region corresponding to one of the first vias, and the P-type doped polysilicon layer has a plurality of second countersunk holes in the region corresponding to one of the second vias, wherein the number of second countersunk holes corresponding to each second via is greater than the number of first countersunk holes corresponding to each first via.

[0029] In some embodiments, the diameter of the second countersunk hole is larger than the diameter of the first countersunk hole.

[0030] In some embodiments, the distribution density of the second countersunk hole is greater than that of the first countersunk hole.

[0031] In some embodiments, the depth to which the second electrode penetrates the P-type doped polysilicon layer is greater than the depth to which the first electrode penetrates the N-type doped polysilicon layer.

[0032] In some embodiments, the ratio of the depth of the second electrode penetrating the P-type doped polysilicon layer to the depth of the first electrode penetrating the N-type doped polysilicon layer is 1 to 2.

[0033] In some embodiments, the ratio of the depth of the second electrode penetrating the P-type doped polysilicon layer to the depth of the first electrode penetrating the N-type doped polysilicon layer is 1.01 to 1.5.

[0034] In some embodiments, the solar cell includes a plurality of first electrodes and a plurality of second electrodes, wherein the width of at least one of the second electrodes is not equal to the width of at least one of the first electrodes.

[0035] In some embodiments, the solar cell is a back-contact solar cell, wherein the N-region and the P-region are located on the same side of the silicon substrate.

[0036] In some embodiments, the solar cell is a bifacial solar cell, wherein the N-region and the P-region are located on opposite sides of the silicon substrate.

[0037] This disclosure also provides a battery assembly including the solar cell described above.

[0038] This disclosure also provides a photovoltaic system including the aforementioned battery module.

[0039] This disclosure provides a solar cell comprising at least one N-region and at least one P-region. An N-type doped polycrystalline silicon layer is disposed in the N-region, and a P-type doped polycrystalline silicon layer is disposed in the P-region. A plurality of first vias are disposed in a first passivation layer on the side of the N-type doped polycrystalline silicon layer facing away from the silicon substrate, and a plurality of second vias are disposed in a second passivation layer on the side of the P-type doped polycrystalline silicon layer facing away from the silicon substrate. A first electrode passes through the plurality of first vias to contact the N-type doped polycrystalline silicon layer, and a second electrode passes through the plurality of second vias to contact the P-type doped polycrystalline silicon layer. This increases the opening area of ​​the second vias, making the contact area between the second electrode and the P-type doped polycrystalline silicon layer larger than the contact area between the first electrode and the N-type doped polycrystalline silicon layer. This increases the contact area between the second electrode and the P-type doped polycrystalline silicon layer, thereby increasing the bonding pull between the P-type doped polycrystalline silicon layer and the second electrode, improving the reliability of the cell structure. Furthermore, by increasing the contact area between the second electrode and the P-type doped polycrystalline silicon layer, a good ohmic contact is formed, improving the conductivity of the P-region, thereby increasing the cell conversion efficiency. Attached Figure Description

[0040] Figure 1 is a cross-sectional schematic diagram of the first type of solar cell provided in Embodiment 1 of this disclosure;

[0041] Figure 2 is a cross-sectional schematic diagram of the first type of solar cell structure provided in Embodiment 1 of this disclosure;

[0042] Figure 3 is a schematic diagram of the back of the first type of solar cell provided in Embodiment 1 of this disclosure;

[0043] Figure 4 is a schematic diagram of the back of the second type of solar cell provided in Embodiment 1 of this disclosure;

[0044] Figure 5 is a schematic diagram of the back of the third type of solar cell provided in Embodiment 1 of this disclosure;

[0045] Figure 6 is a schematic diagram of the back of the fourth type of solar cell provided in Embodiment 1 of this disclosure;

[0046] Figure 7 is a schematic diagram of the back of the fifth type of solar cell provided in Embodiment 1 of this disclosure;

[0047] Figure 8 is a schematic diagram of the first through hole and the first countersunk hole of a solar cell provided in Embodiment 1 of this disclosure;

[0048] Figure 9 is a schematic diagram of the second through hole and the second countersunk hole of a solar cell provided in Embodiment 1 of this disclosure;

[0049] Figure 10 is a cross-sectional schematic diagram of a solar cell provided in Embodiment 2 of this disclosure;

[0050] Figure 11 is a front view of a solar cell provided in Embodiment 2 of this disclosure;

[0051] Figure 12 is a schematic diagram of the back side of a solar cell provided in Embodiment 2 of this disclosure. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this disclosure.

[0053] This disclosure provides a solar cell with at least one N-region and at least one P-region. An N-type doped polycrystalline silicon layer is disposed in the N-region, and a P-type doped polycrystalline silicon layer is disposed in the P-region. A plurality of first vias are disposed in a first passivation layer on the side of the N-type doped polycrystalline silicon layer facing away from the silicon substrate, and a plurality of second vias are disposed in a second passivation layer on the side of the P-type doped polycrystalline silicon layer facing away from the silicon substrate. A first electrode passes through the plurality of first vias to contact the N-type doped polycrystalline silicon layer, and a second electrode passes through the plurality of second vias to contact the P-type doped polycrystalline silicon layer. This increases the opening area of ​​the second vias, making the contact area between the second electrode and the P-type doped polycrystalline silicon layer larger than the contact area between the first electrode and the N-type doped polycrystalline silicon layer. This increases the contact area between the second electrode and the P-type doped polycrystalline silicon layer, thereby increasing the bonding pull between the P-type doped polycrystalline silicon layer and the second electrode, improving the reliability of the cell structure. Furthermore, by increasing the contact area between the second electrode and the P-type doped polycrystalline silicon layer, a good ohmic contact is formed, improving the conductivity of the P-region, thereby increasing the cell conversion efficiency.

[0054] Example 1

[0055] Please refer to Figures 1-7. An embodiment of this disclosure provides a solar cell, comprising:

[0056] A silicon substrate 1, comprising 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 side of the silicon substrate 1;

[0057] An N-type doped polysilicon layer 2 is disposed on the N-region 11;

[0058] A P-type doped polysilicon layer 3 is disposed on the P-region 12;

[0059] The first passivation layer 4 located in the N region 11 is disposed on the side of the N-type doped polysilicon layer 2 facing away from the silicon substrate 1, and the first passivation layer 4 is provided with a plurality of first through holes 41 along its thickness direction.

[0060] The second passivation layer 5 located in the P region 12 is disposed on the side of the P-type doped polysilicon layer 3 facing away from the silicon substrate 1, and a number of second through holes 51 are provided in the second passivation layer 5 along its thickness direction.

[0061] A first electrode 6 is provided in N region 11, and the first electrode 6 passes through a plurality of first through holes 41 to contact the N-type doped polysilicon layer 2.

[0062] A second electrode 7 is provided in the P region 12. The second electrode 7 passes through a number of second through holes 51 and contacts the P-type doped polysilicon layer 3.

[0063] The contact area between the second electrode 7 and the P-type doped polysilicon layer 3 is greater than the contact area between the first electrode 6 and the N-type doped polysilicon layer 2.

[0064] The solar cell provided in this embodiment of the present disclosure has a plurality of first through holes 41 formed in a first passivation layer 4 on the side of the N-type doped polycrystalline silicon layer 2 facing away from the silicon substrate 1, and a plurality of second through holes 51 formed in a second passivation layer 5 on the side of the P-type doped polycrystalline silicon 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 polycrystalline silicon layer 2, and a second electrode 7 passes through the plurality of second through holes 51 to contact the P-type doped polycrystalline silicon layer 3. By increasing the opening area of ​​the second through-hole 51, the second electrode 7 can conduct electricity through the second through-hole 51 with a larger opening area, making the contact area of ​​the P-type doped polycrystalline silicon layer 3 larger than that of the first electrode 6 and the N-type doped polycrystalline silicon layer 2. Compared with the contact area of ​​the first electrode 6 and the N-type doped polycrystalline silicon layer 2, the increased contact area between the second electrode 7 and the P-type doped polycrystalline silicon layer 3 increases the bonding pull between the P-type doped polycrystalline silicon layer 3 and the second electrode 7, making the connection between the second electrode 7 and the P-type doped polycrystalline silicon layer 3 more stable and reliable, which can improve the reliability of the battery structure and the mechanical stability of the battery. Moreover, by increasing the contact area between the second electrode 7 and the P-type doped polycrystalline silicon layer 3, the second electrode 7 and the P-type doped polycrystalline silicon layer 3 form a better ohmic contact, improving the conductivity of the second electrode 7 and the P-type doped polycrystalline silicon layer 3, improving the conductivity of the P-region 12, balancing the conductivity of the N-region 11 and the P-region 12, and improving the conversion efficiency of the solar cell.

[0065] In this embodiment, both the first through hole 41 and the second through hole 51 can be formed by laser drilling or prepared by other processes. The arrangement of the first through hole 41 and the second through hole 51 facilitates the preparation of the first electrode 6 and the second electrode 7 using an electroplating process.

[0066] In this embodiment of the disclosure, the solar cell is a back-contact solar cell, which includes a light-facing surface 101 and a back-facing surface 102 opposite to the light-facing surface 101. The N-region 11 and the P-region 12 are both located on the back-facing surface 102 of the solar cell.

[0067] In this embodiment, 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 is provided between adjacent N-regions 11 and P-regions 12 to isolate the N-regions 11 and P-regions 12, and the isolation region 13 can be a trench.

[0068] In this embodiment of the disclosure, the specific number of 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 rows; the specific number of 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 rows.

[0069] In this context, the size and shape of all first through holes 41 within each N region 11 can be the same or different; the size and shape of all second through holes 51 within each P region 12 can also be the same or different. Figure 3 illustrates that there are 5 first through holes 41 in each N region 11, arranged in a row; and 5 second through holes 51 in each P region 12, also arranged in a row. Both the first through holes 41 and the second through holes 51 shown in Figure 3 are circular through holes, and the diameter of the second through hole 51 is larger than the diameter of the first through hole 41.

[0070] As an embodiment of this disclosure, the solar cell further includes a first tunneling layer 8 disposed between the N-type doped polycrystalline silicon layer 2 and the surface of the silicon substrate 1, and a second tunneling layer 9 disposed between the P-type doped polycrystalline silicon layer 3 and the surface of the silicon substrate 1.

[0071] In this embodiment, the first tunneling layer 8 and the second tunneling layer 9 can be silicon oxide layers. By utilizing the tunneling passivation effect of the first tunneling layer 8 and the second tunneling layer 9, the cell efficiency of the solar cell can be further improved.

[0072] As one embodiment of this disclosure, the total area of ​​the second through hole 51 per unit area is greater than the total area of ​​the first through hole 41 per unit area.

[0073] The unit area can be the total area of ​​the entire solar cell or a portion of the solar cell's area. This can be understood as follows: under the same unit area, the sum of the areas of all second through-holes 51 within that unit area is greater than the sum of the areas of all first through-holes 41 within that unit area. In other words, compared to the first electrode 6, the second electrode 7 can contact the P-type doped polycrystalline silicon layer 3 through second through-holes 51 with a larger total area, thereby increasing the contact area between the second electrode 7 and the P-type doped polycrystalline silicon layer 3, and thus improving the bonding strength and conductivity between the second electrode 7 and the P-type doped polycrystalline silicon layer 3. In this embodiment, the area of ​​the first through-hole 41 is the area of ​​its cross-section; the area of ​​the second through-hole 51 is the area of ​​its cross-section.

[0074] In this embodiment, the first electrode 6 and the second electrode 7 can be fabricated using screen printing or electroplating. The paste for the first electrode 6 fills into the first through-hole 41 and contacts the N-type doped polysilicon layer 2, while the paste for the second electrode 7 fills 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 per unit area is greater than the sum of the areas of all the first through-holes 41 per unit area, the second electrode 7 can have more paste passing through the second through-holes 51 to contact the P-type doped polysilicon layer 3, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0075] In this embodiment of the disclosure, both the second through hole 51 and the first through hole 41 can be circular through holes, square through holes, elliptical holes, polygonal through holes, or irregular through holes.

[0076] As shown in Figure 3, in one embodiment of this disclosure, the area of ​​any second through hole 51 is greater than the area of ​​any first through hole 41.

[0077] In this embodiment, the shapes of the second through-hole 51 and the first through-hole 41 can be the same or different. 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 greater than the contact area between the N-type doped polysilicon layer 2 of any N-region 11 and the first electrode 6. This improves the conductivity and bonding strength between each second electrode 7 and the P-type doped polysilicon layer 3. For example, when both the second through-hole 51 and the first through-hole 41 are circular, the diameter of the second through-hole 51 is larger than the diameter of the first through-hole 41, making the area of ​​any second through-hole 51 larger than the area of ​​any first through-hole 41. When both the second through-hole 51 and the first through-hole 41 are irregular through-holes, it is sufficient that the sum of the areas of all second through-holes 51 within a unit area is greater than the sum of the areas of all first through-holes 41 within a unit area.

[0078] Please refer to Figure 4. As an embodiment of this disclosure, the number of second through holes 51 per unit area is greater than the number of first through holes 41 per unit area.

[0079] In this embodiment, under the premise of the same unit area, the number of all second through holes 51 in the unit area is greater than the number of all first through holes 41 in 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 more second through holes 51, thereby further increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0080] As shown in Figure 4, each N region 11 has 5 first through holes 41 and each P region 12 has 9 second through holes 41, which can further increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0081] As shown in Figure 4, as an optional embodiment of this disclosure, 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 greater than the number of first through holes 41 per unit area. This 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.

[0082] As shown in Figure 5, in one embodiment of this disclosure, the aperture of the second via 51 in each N region 11 is greater than or equal to the aperture of the first via 41 in each P region 11; the center-to-center distance L2 between two adjacent second vias 51 in each N region 11 is greater than the center-to-center distance L1 between two adjacent first vias 41 in each P region 11, making the distribution density of the first vias 41 in the P region 11 denser per unit area, and making the total area of ​​the second vias 51 in each P region 11 greater than the total area of ​​the first vias 41 in each N region 11, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0083] As an optional embodiment of this disclosure, both the first through hole 41 and the second through hole 51 are circular through holes, with diameters of 18–22 μm. For example, the diameters of both the first through hole 41 and the second through hole 51 can be 20 μm. The center-to-center distance between two adjacent second through holes 51 in each P region 12 is 78–85 μm, and the center-to-center distance between two adjacent first through holes 41 in each N region 11 is 86–90 μm. Of course, the dimensions of the first through hole 41 and the second through hole 51 are not limited to these and can be flexibly set in practical applications.

[0084] As an embodiment of this disclosure, 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 to 1.5, and is not equal to 1.

[0085] 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 to 1.5, and not equal to 1. This can be understood as the ratio of the total area of ​​the second via 51 per unit area to the total area of ​​the first via 41 per unit area being 1 to 1.5, and not equal to 1. Specifically, 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, 1.05, 1.1, 1.15, 1.2, 1.23, 1.28, 1.3, 1.35, 1.38, 1.4, 1.42, 1.47, or 1.5.

[0086] 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. This allows 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 to have a suitable difference, and facilitates the setting of the first through hole 41 and the second through hole 51.

[0087] As an embodiment of this disclosure, 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 the contact areas of the two electrodes, and is beneficial to make 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 suitable difference.

[0088] As shown in Figure 3, in one embodiment of this disclosure, the distance d1 between the edges of two adjacent second through holes 51 in each P region 12 is less than the distance d2 between the edges of two adjacent first through holes 41 in each N region 11.

[0089] In this embodiment, the distance d1 between the edges of adjacent second vias 51 in each P region 12 is less than the distance d1 between the edges of two adjacent first vias 41 in each N region 11. This can be understood as the second vias 51 in the P region 12 occupying a larger area. Compared with the first electrode 6, the second electrode 7 can contact the P-type doped polysilicon layer 3 through the larger area of ​​the second vias 51, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 and thus improving the bonding pull between the second electrode 7 and the P-type doped polysilicon layer 3.

[0090] Please refer to Figure 3. As an embodiment of this disclosure, the distance d4 between the first through holes 41 of at least two adjacent N regions 11 is greater than the distance d3 between the second through holes 51 of two adjacent P regions 12.

[0091] This can be understood as follows: among all N regions 11 and all P regions 12, at least the distance between the first vias 41 of two adjacent N regions 11 is greater than the distance between the second vias 51 of two adjacent P regions 12, which can further increase the size of the second vias 51, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0092] Referring to Figure 6, as an embodiment of this disclosure, the silicon substrate 1 includes a first side 15 and a second side 16 opposite to the first side 15. The distance d9 between the edge of the first via 41 of the N region 11 near the first side 15 and the first side 15 is greater than the distance d10 between the second via 51 of the P region 12 near the second side 16 and the second side 16.

[0093] In this embodiment, the 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 the distance d10 between the second through hole 51 corresponding to the P region 12 near the second side and the second side 16. This can be understood as the second through hole 51 in the P region 12 at the edge occupies a larger area in the P region 12 than the first through hole 41 in the N region 11 at the edge. Therefore, the contact area between the second electrode 7 at the edge and the P-type doped polycrystalline silicon layer 3 is increased, thereby improving the bonding pull and conductivity between the second electrode 7 at the edge and the P-type doped polycrystalline silicon layer 3, and improving the reliability and efficiency of the battery structure.

[0094] As an embodiment of this disclosure, the ratio of the area of ​​all second vias 51 in P region 12 to the area of ​​P region 12 is greater than the ratio of the area of ​​all first vias 41 in N region 11 to the area of ​​N region 11. That is, the area ratio of the second vias 51 in P region 12 is greater than the area ratio of the first vias 41 in N region 11, which can further increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0095] Referring to Figure 7, as an embodiment of this disclosure, the solar cell includes at least a first N region 111, a second N region 112, and a third N region 113 arranged sequentially. The distance d5 from the edge of the first through hole 41 in the second N region 112 to the edge of the first through hole 41 in the first N region 111 is not equal to the distance d6 from the edge of the first through hole 41 in the second N region 112 to the edge of the first through hole 41 in the third N region 113.

[0096] In this embodiment, the solar cell includes at least three N regions 11, namely 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 of the second N region 112 to the edge of the first through hole 41 of the third N region 113. This allows the distance between the two sets of first through holes 41 of adjacent N regions 11 to be changed by adjusting the width of some N regions 11 or by adjusting the width of the isolation region 13. This makes the width of the N regions 11 and the spacing between adjacent N regions 11 differentiated, which can improve the light absorption range and photoelectric conversion efficiency of the solar cell and maximize the utilization of light energy resources.

[0097] As an embodiment of this disclosure, the solar cell includes at least a first P region 121, a second P region 122 and a third P region 123 arranged sequentially. The distance d7 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 first P region 121 is not equal to the distance d8 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.

[0098] 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. By adjusting the width of some P regions 12 or adjusting the width of the isolation region 13, the width of the P region 12 and the spacing between two adjacent P regions 12 can be differentiated, which can improve the light absorption range and photoelectric conversion efficiency of the solar cell and maximize the utilization of light energy resources.

[0099] As shown in Figure 7, by increasing the width of the isolation zone 13 between the second P zone 122 and the second N zone 112, the distance between the second N zone 112 and the third N zone 113 can be made greater than the distance between the second N zone 112 and the first N zone 111. At the same time, the distance between the second P zone 122 and the third P zone 123 can be made greater than the distance between the second P zone 122 and the first P zone 121. This makes the width of the P zone 12 and the distance between two adjacent P zones 12 different, and also makes the width of the N zone 11 and the distance between adjacent N zones 11 different.

[0100] As an embodiment of this disclosure, the diameter of the first through hole 41 of at least one N region 11 is not equal to the diameter of the first through hole 41 of at least one N region 11.

[0101] In this 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. This can be understood as follows: 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 of 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 N region 11, so that the width of at least one first electrode 6 is different from the width of the other first electrodes 6. This can achieve a differentiated design of the width of the first electrode 6, improve the light absorption range and photoelectric conversion efficiency of the solar cell, and maximize the utilization of light energy resources.

[0102] As one embodiment of this disclosure, the diameter of the second through hole 51 of at least one P region 12 is not equal to the diameter of the second through hole 51 of at least one P region 12.

[0103] In this 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. This can be understood as follows: 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 of 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 P region 12. This allows the width of at least one second electrode 7 to be different from the width of the other second electrodes 7, enabling a differentiated design of the width of the second electrode 7. This can further improve the light absorption range and photoelectric conversion efficiency of the solar cell and maximize the utilization of light energy resources.

[0104] As one embodiment of this disclosure, the solar cell includes a plurality of first electrodes 6 and a plurality of second electrodes 7, wherein 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.

[0105] In this embodiment, multiple first electrodes 6 are respectively disposed in the N region 11, and multiple second electrodes 7 are respectively disposed in the P region 12. At least one second electrode 7 has a width greater than at least one first electrode 6, and at least one second electrode 7 has a width less than at least one first electrode 6. This means the widths of the second electrodes 7 and the first electrodes 6 are not identical, allowing for flexible adjustment of the width difference between the first electrodes 6 and the second electrodes 7, rather than using electrodes of a single width. This improves the light absorption range and photoelectric conversion efficiency of the solar cell, maximizes the utilization of light energy resources, and significantly increases the probability of photocurrent collection without affecting production capacity.

[0106] 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 allows for the optimal design of the widths of the first electrode 6 and the second electrode 7, thereby improving battery efficiency.

[0107] Referring to Figures 8 and 9, as an embodiment of this disclosure, the N-type doped polysilicon layer 2 has a plurality of first countersunk holes 21 in the region corresponding to a first through-hole 41, and the P-type doped polysilicon layer 3 has a plurality of second countersunk holes 31 in the region corresponding to a second through-hole 51. 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.

[0108] In this embodiment, by providing a plurality of first countersunk holes 21 in the region corresponding to the first through-hole 41 of the N-type doped polysilicon layer 2, and providing a plurality of second countersunk holes 31 in the region corresponding to the second through-hole 51 of the P-type doped polysilicon layer 3, the first electrode 6 can enter the first through-hole 41 and contact the first countersunk holes 21, thereby improving the contact effect between the first electrode 6 and the N-type doped polysilicon layer 2. Similarly, the second electrode 7 can enter the second through-hole 51 and contact the second countersunk holes 31, thereby improving the contact effect between the second electrode 7 and the P-type doped polysilicon layer 3. Furthermore, 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 a larger number of second countersunk holes 31, further increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3. Both the first countersunk holes 21 and the second countersunk holes 31 can be circular.

[0109] As one embodiment of this disclosure, the diameter of the second countersunk hole 31 is larger than the diameter of the first countersunk hole 21.

[0110] In this embodiment, since the diameter of the second countersunk hole 31 is larger than that of the first countersunk hole 21, the area of ​​each second countersunk hole 31 is larger than that 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.

[0111] As one embodiment of this disclosure, the distribution density of the second countersunk hole 31 is greater than that of the first countersunk hole 21.

[0112] In this embodiment, the distribution density of the second countersunk holes 31 is greater than that of the first countersunk holes 21. This can be understood as the number of second countersunk holes 31 per unit area being greater than the number of first countersunk holes 21, allowing the second electrode 7 to contact a larger area of ​​the second countersunk holes 31, thereby further increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3. Furthermore, the depth of the second countersunk holes 31 is greater than the depth of the first countersunk holes 21, which further increases the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0113] As an embodiment of this disclosure, the second electrode 7 penetrates the P-type doped polysilicon layer 3 to a greater depth than the first electrode 6 penetrates the N-type doped polysilicon layer 2.

[0114] In this embodiment, after the paste of the second electrode 7 passes through the second through hole 51, the paste of the second electrode 7 can enter the interior of the P-type doped polysilicon layer 3. After the paste of the first electrode 6 passes through the first through hole 41, the paste of the first electrode 6 can enter the interior of the N-type doped polysilicon layer 2. 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.

[0115] Specifically, when the first electrode 6 and the second electrode 7 are prepared using screen printing, the paste ratio of the second electrode 7 and the first electrode 6 can be adjusted to make the pastes of the second electrode 7 and the first electrode 6 have different burn-through capabilities. The burn-through capability of the paste of the second electrode 7 is greater than that of the paste 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 that 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.

[0116] As an embodiment of this disclosure, 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 to 2.

[0117] In this embodiment, the ratio of the depth of the second electrode 7 penetrating the P-type doped polysilicon layer 3 to the depth of the first electrode 6 penetrating the N-type doped polysilicon layer 2 can be 1.0, 1.01, 1.20, 1.35, 1.55, 1.60, 1.80, 1.90, or 2.0. In some embodiments, the ratio of the depth of the second electrode 7 penetrating the P-type doped polysilicon layer 3 to the depth of the first electrode 6 penetrating the N-type doped polysilicon layer 2 is greater than 1, that is, the depth of the second electrode 7 penetrating the P-type doped polysilicon layer 3 is greater than the depth of the first electrode 6 penetrating the N-type doped polysilicon layer 2.

[0118] In a preferred embodiment of this disclosure, 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. This 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 suitable difference.

[0119] As an embodiment of this disclosure, the first passivation layer 4 and the second passivation layer 5 are both at least one or a combination of aluminum oxide film, silicon oxide film, silicon nitride film, silicon carbide film, and silicon oxynitride film. For example, in some embodiments, both the first passivation layer 4 and the second passivation layer 5 may include aluminum oxide film and silicon nitride film layer stacked sequentially.

[0120] Example 2

[0121] Please refer to Figures 10-12. An embodiment of this disclosure provides a solar cell, comprising:

[0122] The silicon substrate 1 includes at least one N-region 11 and at least one P-region 12, with the N-region 11 and the P-region 12 located on opposite sides of the silicon substrate 1, respectively.

[0123] An N-type doped polysilicon layer 2 is disposed on the N-region 11;

[0124] A P-type doped polysilicon layer 3 is disposed on the P-region 12;

[0125] The first passivation layer 4 is disposed on the side of the N-type doped polysilicon layer 2 facing away from the silicon substrate 1, and the first passivation layer 4 has a plurality of first through holes 41 extending through it along its thickness direction;

[0126] The second passivation layer 5 is disposed on the side of the P-type doped polysilicon layer 3 facing away from the silicon substrate 1, and the second passivation layer 5 has a plurality of second through holes 51 disposed through it along its thickness direction.

[0127] 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 to contact the N-type doped polysilicon layer 2.

[0128] The second electrode 7 is disposed on the second passivation layer 5, and the second electrode 7 passes through a number of second through holes 51 to contact the P-type doped polysilicon layer 3.

[0129] The contact area between the second electrode 7 and the P-type doped polysilicon layer 3 is greater than the contact area between the first electrode 6 and the N-type doped polysilicon layer 2.

[0130] The difference between the solar cell in this embodiment and that in Embodiment 1 is that the solar cell in this embodiment is a bifacial solar cell, with N region 11 and P region 12 located on opposite sides of the silicon substrate 1, while the other structures are the same as in Embodiment 1.

[0131] In this embodiment of the present disclosure, the solar cell includes a first surface and a second surface opposite to the first surface; one of the first surface and the second surface is the light-facing surface 101 of the solar cell, and the other is the back-lighting surface 102 of the solar cell. In Figure 10, the N-regions 11 of the solar cell are sequentially spaced on the back-lighting surface 102 of the silicon substrate 1, and the P-regions 12 are sequentially spaced on the light-facing surface 101 of the silicon substrate 1. Alternatively, the N-regions 11 can also be sequentially spaced on the light-facing surface 101 of the silicon substrate 1, and the P-regions 12 can be sequentially spaced on the back-lighting surface 102 of the silicon substrate 1.

[0132] In this embodiment, there are multiple N-regions 11 and P-regions 12, and a first isolation zone 18 is provided between two adjacent N-regions 11, and a second isolation zone 19 is provided between two adjacent P-regions 12. Of course, the first isolation zone 18 may not be provided between two adjacent N-regions 11, and the second isolation zone 19 may not be provided between two adjacent P-regions 12.

[0133] The solar cell provided in this embodiment of the present disclosure has a plurality of first through holes 41 formed in a first passivation layer 4 on the side of the N-type doped polycrystalline silicon layer 2 facing away from the silicon substrate 1, and a plurality of second through holes 51 formed in a second passivation layer 5 on the side of the P-type doped polycrystalline silicon 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 polycrystalline silicon layer 2, and a second electrode 7 passes through the plurality of second through holes 51 to contact the P-type doped polycrystalline silicon layer 3. By increasing the opening area of ​​the second through-hole 51, the second electrode 7 can conduct electricity through the second through-hole 51 with a larger opening area, making the contact area of ​​the P-type doped polycrystalline silicon layer 3 larger than that of the first electrode 6 and the N-type doped polycrystalline silicon layer 2. Compared with the contact area of ​​the first electrode 6 and the N-type doped polycrystalline silicon layer 2, the increased contact area between the second electrode 7 and the P-type doped polycrystalline silicon layer 3 increases the bonding pull between the P-type doped polycrystalline silicon layer 3 and the second electrode 7, making the connection between the second electrode 7 and the P-type doped polycrystalline silicon layer 3 more stable and reliable, which can improve the reliability of the battery structure and the mechanical stability of the battery. Moreover, by increasing the contact area between the second electrode 7 and the P-type doped polycrystalline silicon layer 3, the second electrode 7 and the P-type doped polycrystalline silicon layer 3 form a better ohmic contact, improving the conductivity of the second electrode 7 and the P-type doped polycrystalline silicon layer 3, improving the conductivity of the P-region 12, balancing the conductivity of the N-region 11 and the P-region 12, and improving the conversion efficiency of the solar cell.

[0134] As an embodiment of this disclosure, the first surface of the silicon substrate 1 is provided with a plurality of N regions 11 and a plurality of first isolation regions 18, the N regions 11 and the first isolation regions 18 being alternately arranged in sequence; the second surface of the silicon substrate 1 has a plurality of P regions 12 and a plurality of second isolation regions 19, the P regions 12 and the second isolation regions 19 being alternately arranged in sequence; the N-type doped polysilicon layer 2 is disposed on the N regions 11 and does not cover the first isolation regions 18; the P-type doped polysilicon layer 3 is disposed on the P regions 12 and does not cover the second isolation regions 19.

[0135] 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. This effectively reduces 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.

[0136] In some other embodiments, N region 11 may also cover the entire first surface, and P region 12 may also cover the entire second surface.

[0137] In this embodiment of the disclosure, the specific number of 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 rows; the specific number of 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 rows.

[0138] In this context, the size and shape of all first through holes 41 within each N region 11 can be the same or different; the size and shape of all second through holes 51 within each P region 12 can also be the same or different. Figure 11 illustrates that each P region 12 has 5 first through holes 41 arranged in a row; each N region 11 has 3 second through holes 51 arranged in a row; both the first through holes 41 and the second through holes 51 shown in Figure 11 are circular through holes, and the diameter of the second through hole 51 is larger than the diameter of the first through hole 41.

[0139] In this embodiment, both the first through hole 41 and the second through hole 51 can be formed by laser drilling or prepared by other processes. The arrangement of the first through hole 41 and the second through hole 51 facilitates the preparation of the first electrode 6 and the second electrode 7 using an electroplating process.

[0140] In this embodiment of the disclosure, the specific number of 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 rows; the specific number of 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 rows.

[0141] In this context, the size and shape of all first through holes 41 within each N region 11 can be the same or different; the size and shape of all second through holes 51 within each P region 12 can also be the same or different. Figure 11 illustrates that each N region 11 has three first through holes 41 arranged in a row; each P region 12 has five second through holes 51 arranged in a row. Both the first through holes 41 and the second through holes 51 are circular through holes, and the diameter of the second through hole 51 is larger than the diameter of the first through hole 41.

[0142] As an embodiment of this disclosure, the solar cell further includes a first tunneling layer 8 disposed between the N-type doped polycrystalline silicon layer 2 and the surface of the silicon substrate 1, and a second tunneling layer 9 disposed between the P-type doped polycrystalline silicon layer 3 and the surface of the silicon substrate 1.

[0143] In this embodiment, the first tunneling layer 8 and the second tunneling layer 9 can be silicon oxide layers. By utilizing the tunneling passivation effect of the first tunneling layer 8 and the second tunneling layer 9, the cell efficiency of the solar cell can be further improved.

[0144] As one embodiment of this disclosure, the total area of ​​the second through hole 51 per unit area is greater than the total area of ​​the first through hole 41 per unit area.

[0145] The unit area can be the total area of ​​the entire solar cell or a portion of the solar cell's area. This can be understood as follows: under the same unit area, the sum of the areas of all second through-holes 51 within that unit area is greater than the sum of the areas of all first through-holes 41 within that unit area. In other words, compared to the first electrode 6, the second electrode 7 can contact the P-type doped polycrystalline silicon layer 3 through second through-holes 51 with a larger total area, thereby increasing the contact area between the second electrode 7 and the P-type doped polycrystalline silicon layer 3, and thus improving the bonding strength and conductivity between the second electrode 7 and the P-type doped polycrystalline silicon layer 3. In this embodiment, the area of ​​the first through-hole 41 is the area of ​​its cross-section; the area of ​​the second through-hole 51 is the area of ​​its cross-section.

[0146] In this embodiment, the first electrode 6 and the second electrode 7 can be fabricated using screen printing or electroplating. The paste for the first electrode 6 fills into the first through-hole 41 and contacts the N-type doped polysilicon layer 2, while the paste for the second electrode 7 fills 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 per unit area is greater than the sum of the areas of all the first through-holes 41 per unit area, the second electrode 7 can have more paste passing through the second through-holes 51 to contact the P-type doped polysilicon layer 3, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0147] In this embodiment of the disclosure, both the second through hole 51 and the first through hole 41 can be circular through holes, square through holes, elliptical holes, polygonal through holes, or irregular through holes.

[0148] As an embodiment of this disclosure, the area of ​​any second through hole 51 is greater than the area of ​​any first through hole 41.

[0149] In this embodiment, the shapes of the second through-hole 51 and the first through-hole 41 can be the same or different. 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 greater than the contact area between the N-type doped polysilicon layer 2 of any N-region 11 and the first electrode 6. This improves the conductivity and bonding strength between each second electrode 7 and the P-type doped polysilicon layer 3. For example, when both the second through-hole 51 and the first through-hole 41 are circular, the diameter of the second through-hole 51 is larger than the diameter of the first through-hole 41, making the area of ​​any second through-hole 51 larger than the area of ​​any first through-hole 41. When both the second through-hole 51 and the first through-hole 41 are irregular through-holes, it is sufficient that the sum of the areas of all second through-holes 51 within a unit area is greater than the sum of the areas of all first through-holes 41 within a unit area.

[0150] As one embodiment of this disclosure, the number of second through holes 51 per unit area is greater than the number of first through holes 41 per unit area.

[0151] In this embodiment, under the premise of the same unit area, the number of all second through holes 51 in the unit area is greater than the number of all first through holes 41 in 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 more second through holes 51, thereby further increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0152] As an optional embodiment of this disclosure, 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 greater than the number of first through holes 41 per unit area. This 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.

[0153] Similar to Embodiment 1, as an embodiment of this disclosure, the aperture of the second via 51 in each N region 11 is greater than or equal to the aperture of the first via 41 in each P region 11; the center-to-center distance between two adjacent second vias 51 in each N region 11 is greater than the center-to-center distance between two adjacent first vias 41 in each P region 11, making the distribution density of the first vias 41 in the P region 11 denser per unit area, and making the total area of ​​the second vias 51 in each P region 11 greater than the total area of ​​the first vias 41 in each N region 11, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0154] As an optional embodiment of this disclosure, both the first through hole 41 and the second through hole 51 are circular through holes, with diameters of 18–22 μm. For example, the diameters of both the first through hole 41 and the second through hole 51 can be 20 μm. The center-to-center distance between two adjacent second through holes 51 in each P region 12 is 78–85 μm, and the center-to-center distance between two adjacent first through holes 41 in each N region 11 is 86–90 μm. Of course, the dimensions of the first through hole 41 and the second through hole 51 are not limited to these and can be flexibly set in practical applications.

[0155] As an embodiment of this disclosure, 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 to 1.5, and is not equal to 1.

[0156] 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 to 1.5, and not equal to 1. This can be understood as the ratio of the total area of ​​the second via 51 per unit area to the total area of ​​the first via 41 per unit area being 1 to 1.5, and not equal to 1. Specifically, 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, 1.05, 1.1, 1.15, 1.2, 1.23, 1.28, 1.3, 1.35, 1.38, 1.4, 1.42, 1.47, or 1.5.

[0157] 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. This allows 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 to have a suitable difference, and facilitates the setting of the first through hole 41 and the second through hole 51.

[0158] As an embodiment of this disclosure, 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 the contact areas of the two electrodes, and is beneficial to make 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 suitable difference.

[0159] As shown in Figures 11 and 12, in one embodiment of this disclosure, the distance d1 between the edges of two adjacent second through holes 51 in each P region 12 is less than the distance d2 between the edges of two adjacent first through holes 41 in each N region 11.

[0160] In this embodiment, the distance d1 between the edges of adjacent second vias 51 in each P region 12 is less than the distance d1 between the edges of two adjacent first vias 41 in each N region 11. This can be understood as the second vias 51 in the P region 12 occupying a larger area. Compared with the first electrode 6, the second electrode 7 can contact the P-type doped polysilicon layer 3 through the larger area of ​​the second vias 51, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3 and thus improving the bonding pull between the second electrode 7 and the P-type doped polysilicon layer 3.

[0161] Similar to Embodiment 1, as an embodiment of this disclosure, at least the distance between the first through holes 41 of two adjacent N regions 11 is greater than the distance between the second through holes 51 corresponding to two adjacent P regions 12.

[0162] This can be understood as follows: among all N regions 11 and all P regions 12, at least the distance between the first vias 41 of two adjacent N regions 11 is greater than the distance between the second vias 51 of two adjacent P regions 12, which can further increase the size of the second vias 51, thereby increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0163] As an embodiment of this disclosure, the ratio of the area of ​​all second vias 51 in P region 12 to the area of ​​P region 12 is greater than the ratio of the area of ​​all first vias 41 in N region 11 to the area of ​​N region 11. That is, the area ratio of the second vias 51 in P region 12 is greater than the area ratio of the first vias 41 in N region 11, which can further increase the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0164] As an embodiment of this disclosure, the diameter of the first through hole 41 of at least one N region 11 is not equal to the diameter of the first through hole 41 of at least one N region 11.

[0165] In this 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. This can be understood as follows: 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 of 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 N region 11, so that the width of at least one first electrode 6 is different from the width of the other first electrodes 6. This can achieve a differentiated design of the width of the first electrode 6, improve the light absorption range and photoelectric conversion efficiency of the solar cell, and maximize the utilization of light energy resources.

[0166] As one embodiment of this disclosure, the diameter of the second through hole 51 of at least one P region 12 is not equal to the diameter of the second through hole 51 of at least one P region 12.

[0167] In this 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. This can be understood as follows: 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 of 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 P region 12. This allows the width of at least one second electrode 7 to be different from the width of the other second electrodes 7, enabling a differentiated design of the width of the second electrode 7. This can further improve the light absorption range and photoelectric conversion efficiency of the solar cell and maximize the utilization of light energy resources.

[0168] As one embodiment of this disclosure, the solar cell includes a plurality of first electrodes 6 and a plurality of second electrodes 7, wherein 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.

[0169] In this embodiment, multiple first electrodes 6 are respectively disposed in the N region 11, and multiple second electrodes 7 are respectively disposed in the P region 12. At least one second electrode 7 has a width greater than at least one first electrode 6, and at least one second electrode 7 has a width less than at least one first electrode 6. This means the widths of the second electrodes 7 and the first electrodes 6 are not identical, allowing for flexible adjustment of the width difference between the first electrodes 6 and the second electrodes 7, rather than using electrodes of a single width. This improves the light absorption range and photoelectric conversion efficiency of the solar cell, maximizes the utilization of light energy resources, and significantly increases the probability of photocurrent collection without affecting production capacity.

[0170] 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 allows for the optimal design of the widths of the first electrode 6 and the second electrode 7, thereby improving battery efficiency.

[0171] Similar to Embodiment 1, referring again to Figures 8 and 9, as an embodiment of this disclosure, the N-type doped polysilicon layer 2 has a plurality of first countersunk holes 21 in the region corresponding to a first through-hole 41, and the P-type doped polysilicon layer 3 has a plurality of second countersunk holes 31 in the region corresponding to a second through-hole 51. 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.

[0172] In this embodiment, by providing a plurality of first countersunk holes 21 in the region corresponding to the first through-hole 41 of the N-type doped polysilicon layer 2, and providing a plurality of second countersunk holes 31 in the region corresponding to the second through-hole 51 of the P-type doped polysilicon layer 3, the first electrode 6 can enter the first through-hole 41 and contact the first countersunk holes 21, thereby improving the contact effect between the first electrode 6 and the N-type doped polysilicon layer 2. Similarly, the second electrode 7 can enter the second through-hole 51 and contact the second countersunk holes 31, thereby improving the contact effect between the second electrode 7 and the P-type doped polysilicon layer 3. Furthermore, 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 a larger number of second countersunk holes 31, further increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3. Both the first countersunk holes 21 and the second countersunk holes 31 can be circular.

[0173] As one embodiment of this disclosure, the diameter of the second countersunk hole 31 is larger than the diameter of the first countersunk hole 21.

[0174] In this embodiment, since the diameter of the second countersunk hole 31 is larger than that of the first countersunk hole 21, the area of ​​each second countersunk hole 31 is larger than that 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.

[0175] As one embodiment of this disclosure, the distribution density of the second countersunk hole 31 is greater than that of the first countersunk hole 21.

[0176] In this embodiment, the distribution density of the second countersunk holes 31 is greater than that of the first countersunk holes 21. This can be understood as the number of second countersunk holes 31 per unit area being greater than the number of first countersunk holes 21, allowing the second electrode 7 to contact a larger area of ​​the second countersunk holes 31, thereby further increasing the contact area between the second electrode 7 and the P-type doped polysilicon layer 3. Furthermore, the depth of the second countersunk holes 31 is greater than the depth of the first countersunk holes 21, which further increases the contact area between the second electrode 7 and the P-type doped polysilicon layer 3.

[0177] As an embodiment of this disclosure, the second electrode 7 penetrates the P-type doped polysilicon layer 3 to a greater depth than the first electrode 6 penetrates the N-type doped polysilicon layer 2.

[0178] In this embodiment, after the paste of the second electrode 7 passes through the second through hole 51, the paste of the second electrode 7 can enter the interior of the P-type doped polysilicon layer 3. After the paste of the first electrode 6 passes through the first through hole 41, the paste of the first electrode 6 can enter the interior of the N-type doped polysilicon layer 2. 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.

[0179] Specifically, when the first electrode 6 and the second electrode 7 are prepared using screen printing, the paste ratio of the second electrode 7 and the first electrode 6 can be adjusted to make the pastes of the second electrode 7 and the first electrode 6 have different burn-through capabilities. The burn-through capability of the paste of the second electrode 7 is greater than that of the paste 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 that 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.

[0180] As an embodiment of this disclosure, 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 to 2.

[0181] In this embodiment, the ratio of the depth of the second electrode 7 penetrating the P-type doped polysilicon layer 3 to the depth of the first electrode 6 penetrating the N-type doped polysilicon layer 2 can be 1.0, 1.01, 1.20, 1.35, 1.55, 1.60, 1.80, 1.90, or 2.0. In some embodiments, the ratio of the depth of the second electrode 7 penetrating the P-type doped polysilicon layer 3 to the depth of the first electrode 6 penetrating the N-type doped polysilicon layer 2 is greater than 1, that is, the depth of the second electrode 7 penetrating the P-type doped polysilicon layer 3 is greater than the depth of the first electrode 6 penetrating the N-type doped polysilicon layer 2.

[0182] In a preferred embodiment of this disclosure, 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. This 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 suitable difference.

[0183] As an embodiment of this disclosure, the first passivation layer 4 and the second passivation layer 5 are both at least one or a combination of aluminum oxide film, silicon oxide film, silicon nitride film, silicon carbide film, and silicon oxynitride film. For example, in some embodiments, both the first passivation layer 4 and the second passivation layer 5 may include aluminum oxide film and silicon nitride film layer stacked sequentially.

[0184] Example 3

[0185] This disclosure also provides a battery module, which includes the solar cell of Embodiment 1 or Embodiment 2 described above. It should be noted that this battery module has the same or similar beneficial effects as the solar cell, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0186] Example 4

[0187] This disclosure also provides a photovoltaic system, which includes the battery module of Embodiment 3 described above. It should be noted that this photovoltaic system has the same or similar beneficial effects as a solar cell, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0188] This disclosure provides a solar cell with at least one N-region and at least one P-region. An N-type doped polycrystalline silicon layer is disposed in the N-region, and a P-type doped polycrystalline silicon layer is disposed in the P-region. A plurality of first vias are disposed in a first passivation layer on the side of the N-type doped polycrystalline silicon layer facing away from the silicon substrate, and a plurality of second vias are disposed in a second passivation layer on the side of the P-type doped polycrystalline silicon layer facing away from the silicon substrate. A first electrode passes through the plurality of first vias to contact the N-type doped polycrystalline silicon layer, and a second electrode passes through the plurality of second vias to contact the P-type doped polycrystalline silicon layer. This increases the opening area of ​​the second vias, making the contact area between the second electrode and the P-type doped polycrystalline silicon layer larger than the contact area between the first electrode and the N-type doped polycrystalline silicon layer. This increases the contact area between the second electrode and the P-type doped polycrystalline silicon layer, thereby increasing the bonding pull between the P-type doped polycrystalline silicon layer and the second electrode, improving the reliability of the cell structure. Furthermore, by increasing the contact area between the second electrode and the P-type doped polycrystalline silicon layer, a good ohmic contact is formed, improving the conductivity of the P-region, thereby increasing the cell conversion efficiency.

[0189] The above are merely preferred embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A solar cell, characterized by, The solar cell comprises: a silicon substrate comprising at least one N region and at least one P region, the N region and the P region being located on the same side of the silicon substrate, or the N region and the P region being located on opposite sides of the silicon substrate, respectively; an N-type doped polysilicon layer disposed on the N region; a P-type doped polysilicon layer disposed on the P region; a first passivation layer located on the N region, the first passivation layer being disposed on a side of the N-type doped polysilicon layer facing away from the silicon substrate, a plurality of first through holes penetrating the first passivation layer along the thickness direction of the first passivation layer; a second passivation layer located on the P region, the second passivation layer being disposed on a side of the P-type doped polysilicon layer facing away from the silicon substrate, a plurality of second through holes penetrating the second passivation layer along the thickness direction of the second passivation layer; a first electrode disposed on the N region, the first electrode being in contact with the N-type doped polysilicon layer through the plurality of first through holes; a second electrode disposed on the P region, the second electrode being in contact with the P-type doped polysilicon layer through the plurality of second through holes; wherein the contact area of the second electrode with the P-type doped polysilicon layer is greater than the contact area of the first electrode with 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 in a unit area is greater than the total area of the first through holes in the unit area.

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

4. The solar cell of claim 1, wherein The number of the second through holes in a unit area is greater than the number of the first through holes in the unit area.

5. The solar cell of claim 1, wherein The ratio of the contact area of the second electrode with the P-type doped polysilicon layer to the contact area of the first electrode with the N-type doped polysilicon layer is 1-1.5, and is not equal to 1.

6. The solar cell of claim 1, wherein The ratio of the contact area of the second electrode with the P-type doped polysilicon layer to the contact area of the first electrode with the N-type doped polysilicon layer is 1.01-1.

2.

7. The solar cell of claim 1, wherein The distance between the edges of two adjacent second through holes in each P region is less than the distance between the edges of two adjacent first through holes in each N region.

8. The solar cell of claim 1, wherein, The diameters of the first through holes in at least two N regions are not equal.

9. The solar cell of claim 1, wherein, The diameters of the second through holes in at least two P regions are not equal.

10. The solar cell of claim 1, wherein, The silicon substrate comprises a first side edge and a second side edge opposite to the first side edge, the minimum distance between the edge of the first through hole in the N region close to the first side edge and the first side edge is greater than the minimum distance between the second through hole in the P region close to the second side edge and the second side edge.

11. The solar cell of claim 1, wherein, The minimum distance of the first through hole in at least two adjacent N regions is greater than the minimum distance of the second through hole in at least two adjacent P regions.

12. The solar cell of claim 1, wherein, The solar cell comprises a first N region, a second N region, and a third N region arranged in sequence, the minimum distance between the edge of the first through hole in the second N region and the edge of the first through hole in the first N region is not equal to the minimum distance between the edge of the first through hole in the second N region and the edge of the first through hole in the third N region.

13. The solar cell of claim 1, wherein, The solar cell comprises at least a first P region, a second P region and a third P region arranged in sequence, and a minimum distance from an edge of the second via hole in the second P region to an edge of the second via hole in the first P region is not equal to a minimum distance from an edge of the second via hole in the second P region to an edge of the second via hole in the third P region.

14. The solar cell of claim 1, wherein, The N-type doped polysilicon layer is provided with a plurality of first counterbores corresponding to a region of the first via hole, and the P-type doped polysilicon layer is provided with a plurality of second counterbores corresponding to a region of the second via hole, and a number of the second counterbores corresponding to each second via hole is greater than a number of the first counterbores corresponding to each first via hole.

15. The solar cell of claim 14, wherein, A hole diameter of the second counterbores is greater than a hole diameter of the first counterbores.

16. The solar cell of claim 14, wherein, A distribution density of the second counterbores is greater than a distribution density of the first counterbores.

17. The solar cell of claim 1, wherein, A depth of the second electrode into the P-type doped polysilicon layer is greater than a depth of the first electrode into the N-type doped polysilicon layer.

18. The solar cell of claim 1, wherein, A ratio of the depth of the second electrode into the P-type doped polysilicon layer to the depth of the first electrode into the N-type doped polysilicon layer is 1-2.

19. The solar cell of claim 1, wherein, A ratio of the depth of the second electrode into the P-type doped polysilicon layer to the depth of the first electrode into the N-type doped polysilicon layer is 1.01-1.

5.

20. The solar cell of claim 1, wherein, The solar cell comprises 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 of claim 1, wherein, The solar cell is a back contact solar cell, and the N region and the P region are located on a same surface of the silicon substrate.

22. The solar cell of claim 1, wherein, The solar cell is a bifacial solar cell, and the N region and the P region are located on opposite surfaces of the silicon substrate, respectively.

23. A battery assembly characterized by, A solar cell as claimed in any one of claims 1-22.

24. A photovoltaic system characterized by, A battery assembly as claimed in claim 23.

Images