Solar cell and passivation contact structure thereof, cell assembly and photovoltaic system

Abstract

The invention is applicable to the technical field of solar cells, and provides a solar cell and a passivation contact structure thereof, a cell module and a photovoltaic system, and the passivation contact structure of the solar cell comprises a tunneling layer arranged on the surface of a silicon substrate; the first doping layer is arranged on one side, deviating from the silicon substrate, of the tunneling layer; the second doping layer is arranged on the side, away from the silicon substrate, of the first doping layer, and the doping type of the second doping layer is the same as that of the first doping layer; in unit area, the total area of the grain gaps of the second doped layer is larger than the total area of the grain gaps of the first doped layer. The solar cell passivation contact structure provided by the invention can reduce the parasitic absorption of sunlight and improve the utilization efficiency of the sunlight by the solar cell, thereby improving the cell efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a solar cell and a passivation contact structure thereof, a cell 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 double-sided contact 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 the double-sided contact solar cell, the front surface of the back-contact solar cell completely avoids the shading of the metal grid line, eliminating the optical loss caused by the shading of the metal grid line, which can greatly improve the cell conversion efficiency.

[0003] In the prior art, the solar cell passivation contact structure usually includes a tunneling layer and a doping layer stacked in sequence on the surface of a silicon substrate, and the metal electrode of the solar cell contacts the doping layer to achieve the passivation contact of the solar cell. In order to improve the passivation effect of the solar cell passivation contact structure, the solar cell passivation contact structure is provided with at least two doping layers. However, the hollowing degree of each doping layer of the solar cell passivation contact structure is exactly the same, and the parasitic absorption of sunlight is large, which affects the efficiency of the solar cell. Summary of the invention

[0004] The present invention provides a solar cell passivation contact structure, aiming to solve the problem that the solar cell passivation contact structure in the prior art has large parasitic absorption of sunlight and affects the efficiency of the solar cell.

[0005] The present invention is implemented by providing a solar cell passivation contact structure, comprising:

[0006] A tunneling layer disposed on the surface of the silicon substrate;

[0007] A first doped layer, disposed on a side of the tunneling layer away from the silicon substrate;

[0008] A second doping layer, disposed on a side of the first doping layer away from the silicon substrate, the second doping layer having the same doping type as the first doping layer;

[0009] In a unit area, the total area of ​​the grain gaps of the second doping layer is greater than the total area of ​​the grain gaps of the first doping layer.

[0010] Preferably, the first doping layer and the second doping layer are an integrally formed structure or a separately formed structure.

[0011] Preferably, the ratio of the total area of ​​the grain gaps of the second doping layer to the total area of ​​the grain gaps of the first doping layer is 6-10.

[0012] Preferably, within a unit area, the ratio of the area occupied by the grains of the first doping layer to the area occupied by the gaps between the grains is greater than the ratio of the area occupied by the grains of the second doping layer to the area occupied by the gaps between the grains.

[0013] Preferably, the ratio of the total area of ​​the grains of the second doping layer to the total area of ​​the gaps between the grains is 2.3% to 32.3%.

[0014] Preferably, the deposition temperature of the first doping layer is lower than the deposition temperature of the second doping layer, and the flow rate of the reaction gas introduced during the deposition of the first doping layer is the same as the flow rate of the reaction gas introduced during the deposition of the second doping layer.

[0015] Preferably, the deposition temperature of the second doping layer is 586-605°C, and the deposition temperature of the first doping layer is 550-585°C.

[0016] Preferably, the deposition temperature of the first doping layer is greater than the deposition temperature of the second doping layer, and the flow rate of the reaction gas introduced during the deposition of the second doping layer is greater than the flow rate of the reaction gas introduced during the deposition of the first doping layer.

[0017] Preferably, the deposition temperature of the second doping layer is 585-605°C; the deposition temperature of the first doping layer is 606-680°C.

[0018] Preferably, it also includes:

[0019] The passivation layer is disposed between the first doping layer and the second doping layer.

[0020] Preferably, an average grain size of the first doping layer is smaller than an average grain size of the second doping layer.

[0021] Preferably, the first doping layer and / or the second doping layer is one or a combination of at least two of doped polycrystalline silicon, doped microcrystalline silicon, doped nanocrystalline silicon, and doped amorphous silicon.

[0022] The present invention also provides a solar cell, comprising a silicon substrate, wherein the silicon substrate comprises a light-facing surface and a backlight surface arranged opposite to the light-facing surface, and the light-facing surface and / or the backlight surface are provided with the above-mentioned solar cell passivation contact structure.

[0023] Preferably, the solar cell is a back-contact solar cell, the backlight surface is provided with a P region and an N region, and the P region and the N region are both provided with the solar cell passivation contact structure; the second doping layer in the P region is a P-type doping layer, and the second doping layer in the N region is an N-type doping layer.

[0024] Preferably, the solar cell is a double-sided contact solar cell, one of the light-facing surface and the backlight surface is provided with a P region, and the other is provided with an N region, and both the P region and the N region are provided with the solar cell passivation contact structure; the second doping layer in the P region is a P-type doping layer, and the second doping layer in the N region is an N-type doping layer.

[0025] The present invention also provides a battery assembly, comprising the above-mentioned solar cell.

[0026] The present invention also provides a photovoltaic system, comprising the above-mentioned battery assembly.

[0027] A solar cell passivation contact structure provided by the present invention improves the passivation effect of the solar cell by providing a first doping layer and a second doping layer provided on the side of the first doping layer away from the silicon substrate, and utilizes the first doping layer and the second doping layer; moreover, within a unit area, the total area of ​​the grain gaps of the second doping layer is greater than the total area of ​​the grain gaps of the first doping layer, so that the hollowing degree of the second doping layer located in the outer layer is greater than the hollowing degree of the first doping layer located in the inner layer, which can reduce parasitic absorption of sunlight, improve the utilization efficiency of sunlight by the solar cell, and thus improve the battery efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic structural diagram of a solar cell passivation contact structure provided in Embodiment 1 of the present invention;

[0029] Figure 2 This is a SEM image of a second doping layer of a solar cell passivation contact structure provided in Example 1 of the present invention;

[0030] Figure 3 This is a SEM image of a first doping layer of a solar cell passivation contact structure provided in Example 1 of the present invention;

[0031] Figure 4 A schematic diagram of the structure of a solar cell provided in Embodiment 2 of the present invention;

[0032] Figure 5 This is a schematic diagram of the structure of a solar cell provided in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] A solar cell passivation contact structure provided by the present invention is provided with a first doping layer and a second doping layer provided on the side of the first doping layer facing away from the silicon substrate. Within a unit area, the total area of ​​the grain gaps in the second doping layer is larger than the total area of ​​the grain gaps in the first doping layer, so that the hollowing degree of the second doping layer located in the outer layer is larger than the hollowing degree of the first doping layer located in the inner layer. While the first doping layer and the second doping layer are used to improve the passivation effect of the solar cell, the parasitic absorption of sunlight can be reduced, the utilization efficiency of the solar cell for sunlight can be improved, and thus the battery efficiency can be improved.

[0035] Embodiment 1

[0036] Please refer to Figure 1 The present invention provides a solar cell passivation contact structure 1, comprising:

[0037] A tunneling layer 11 disposed on the surface of a silicon substrate 21;

[0038] A first doped layer 12 is disposed on a side of the tunneling layer 11 away from the silicon substrate 21;

[0039] A second doping layer 13 is provided on a side of the first doping layer 12 away from the silicon substrate 21, and the second doping layer 13 has the same doping type as the first doping layer 12;

[0040] In unit area, the total area of ​​the grain gaps of the second doping layer 12 is greater than the total area of ​​the grain gaps of the first doping layer 13 .

[0041] In the embodiment of the present invention, within a unit area, the total area of ​​the grain gaps of the second doping layer 13 is greater than the total area of ​​the grain gaps of the first doping layer 12. It can be understood that, under the premise of the same area, the sum of the areas of all grain gaps in the second doping layer 13 is greater than the sum of the areas of all grain gaps in the first doping layer 12. Among them, the unit area can be the area of ​​the entire second doping layer 13 and the first doping layer 12 or a partial area of ​​the second doping layer 13 and the first doping layer 12. For the first doping layer 12 and the second doping layer 13, the larger the grain gap area, the looser the doping layer structure and the greater the degree of hollowing out of the doping layer; conversely, the smaller the grain gap area, the denser the doping layer structure and the smaller the degree of hollowing out of the doping layer. Among them, as Figure 2-Figure 3 As shown, the total area of ​​the grain gaps of the second doping layer 13 and the total area of ​​the grain gaps of the first doping layer 12 can be measured by SEM. Figure 2 The total area of ​​the grain gaps of the second doped layer 13 shown in FIG. Figure 3 The total area of ​​the grain gaps of the first doped layer 12 is shown.

[0042] The present invention provides a solar cell passivation contact structure. By providing a first doping layer 12 and a second doping layer 13 provided on the side of the first doping layer 12 facing away from a silicon substrate 21, the first doping layer 12 and the second doping layer 13 can be used to improve the passivation effect of the solar cell. Moreover, within a unit area, the total area of ​​the grain gaps of the second doping layer 13 is greater than the total area of ​​the grain gaps of the first doping layer 12, so that the hollowing degree of the second doping layer 13 located in the outer layer is greater than the hollowing degree of the first doping layer 12 located in the inner layer. While the first doping layer 12 and the second doping layer 13 are used to improve the passivation effect, by increasing the total area of ​​the grain gaps of the second doping layer 13, that is, increasing the hollowing degree of the second doping layer 13, the parasitic absorption of sunlight by the doping layer can be reduced, and the utilization efficiency of sunlight by the solar cell can be improved, thereby improving the battery efficiency.

[0043] In the embodiment of the present invention, the silicon substrate 21 can be a P-type silicon substrate or an N-type silicon substrate. The surface of the silicon substrate 21 can be the light-facing surface or the backlight surface of the solar cell. The solar cell passivation contact structure can be arranged in the P region or the N region of the solar cell.

[0044] As an embodiment of the present invention, the tunneling layer 11 is one of silicon oxide, silicon oxynitride, and silicon nitride, or a combination of at least two of them.

[0045] In this embodiment, the material of the tunneling layer 11 can be one of silicon oxide, silicon oxynitride, silicon nitride, or a combination of at least two thereof. The tunneling layer 11 plays a tunneling and passivation function on the surface of the silicon substrate 21, which is beneficial to improving the efficiency of the solar cell. The thickness of the tunneling layer 11 can be set according to actual conditions. For example, the thickness of the tunneling layer 11 can be 0.5 to 5 nanometers.

[0046] Among them, when the solar cell passivation contact structure 1 is set in the P region of the solar cell, the first doping layer 12 and the second doping layer 13 are P-type doping layers, and the electrode in the P region of the solar cell contacts the second doping layer 13; when the solar cell passivation contact structure is set in the N region of the solar cell, the first doping layer 12 and the second doping layer 13 are N-type doping layers, and the electrode in the N region of the solar cell contacts the second doping layer 13.

[0047] As an embodiment of the present invention, the first doping layer 12 and / or the second doping layer 13 is one or a combination of at least two of doped polycrystalline silicon, doped microcrystalline silicon, doped nanocrystalline silicon, and doped amorphous silicon.

[0048] The materials of the first doping layer 12 and the second doping layer 13 may be the same or different, and may be set according to actual needs. The first doping layer 12 and the second doping layer 13 may be doped polycrystalline silicon, doped microcrystalline silicon, doped nanocrystalline silicon or doped amorphous silicon, and the first doping layer 12 and the second doping layer 13 may also be a combination of at least two of doped polycrystalline silicon, doped microcrystalline silicon, doped nanocrystalline silicon or doped amorphous silicon. Preferably, the first doping layer 12 and the second doping layer 13 are both doped polycrystalline silicon.

[0049] In this embodiment, the first doping layer 12 and the second doping layer 13 have the same doping type, and the first doping layer 12 and the second doping layer 13 are P-type doping layers doped with P-type dopants or N-type doping layers doped with N-type dopants. The P-type dopant is a IIIA group element dopant, and the N-type dopant is a VA group element dopant. For example, the P-type dopant may be a boron dopant, and the N-type dopant may be a phosphorus dopant.

[0050] In the embodiment of the present invention, the solar cell passivation contact structure includes at least two doping layers, that is, the solar cell passivation contact structure includes at least a first doping layer 12 and a second doping layer 13. Of course, the solar cell passivation contact structure may also include three or more doping layers. For example, the solar cell passivation contact structure may also include a third doping layer (not shown), and the third doping layer is arranged on the side of the second doping layer 13 away from the silicon substrate 21; within a unit area, the total area of ​​the grain gaps of the third doping layer is greater than the total area of ​​the grain gaps of the second doping layer 13, so that the hollowing degree of the third doping layer located in the outer layer is greater than the hollowing degree of the second doping layer 13 located in the inner layer, which can further improve the cell passivation effect, reduce the parasitic absorption of sunlight, and improve the utilization efficiency of solar cells for sunlight, thereby improving cell efficiency.

[0051] As an embodiment of the present invention, the first doping layer 12 and the second doping layer 13 are an integrally formed structure or a separately formed structure.

[0052] In this embodiment, the first doping layer 12 and the second doping layer 13 are integrally formed structures, or the first doping layer 12 and the second doping layer 13 are separately formed structures. It can be understood that the first doping layer 12 and the second doping layer 13 are single-layer structures formed in one step, and the first doping layer 12 and the second doping layer 13 can also be a stacked structure formed in steps.

[0053] As an embodiment of the present invention, the ratio of the total area of ​​the grain gaps of the second doping layer 13 to the total area of ​​the grain gaps of the first doping layer 12 is 6-10.

[0054] In the present embodiment, the ratio of the total area of ​​the grain gaps of the second doping layer 13 to the total area of ​​the grain gaps of the first doping layer 12 is 6 to 10, so that the difference between the hollowing degree of the second doping layer 13 and the hollowing degree of the first doping layer 12 is within a relatively suitable range, which can not only effectively improve the passivation effect of the battery, but also ensure smaller parasitic absorption of sunlight, thereby improving the utilization efficiency of solar cells for sunlight, thereby improving battery efficiency.

[0055] For example, the ratio of the total area of ​​the grain gaps of the second doping layer 13 to the total area of ​​the grain gaps of the first doping layer 12 may be 6.0, or 6.2, or 6.5, or 6.8, or 7.0, or 7.1, or 7.6, or 7.9, or 8.0, or 8.3, or 8.7, or 9.0, or 9.4, or 9.8, or 10.0.

[0056] As an embodiment of the present invention, the total area of ​​the grain gaps of the first doping layer 12 accounts for 0.5% to 3%, and the total area of ​​the grain gaps of the second doping layer 13 accounts for 3% to 30%.

[0057] In this embodiment, the total area ratio of the grain gaps of the first doping layer 12 is the ratio of the total area of ​​the grain gaps of the first doping layer 12 to the total area of ​​the first doping layer 12 , and the total area ratio of the grain gaps of the second doping layer 13 is the ratio of the total area of ​​the grain gaps of the second doping layer 13 to the total area of ​​the second doping layer 13 .

[0058] It can be understood that, under the same area conditions, the total area ratio of the grain gaps in the first doping layer 12 is 0.5% to 3%, and the total area ratio of the grain gaps in the second doping layer 13 is 3% to 30%. The total area ratio of the grain gaps in the second doping layer 13 and the total area ratio of the grain gaps in the first doping layer 12 are set within a more appropriate range, which can effectively improve the battery passivation effect, improve the utilization efficiency of solar cells for sunlight, thereby improving battery efficiency, and facilitate the processing and preparation of the first doping layer 12 and the second doping layer 13.

[0059] As an embodiment of the present invention, within a unit area, the ratio of the total area of ​​grains of the first doping layer 12 to the total area of ​​grain gaps is greater than the ratio of the total area of ​​grains of the second doping layer 13 to the total area of ​​grain gaps.

[0060] In this embodiment, the ratio of the total area of ​​grains of the first doping layer 12 to the total area of ​​grain gaps can be understood as the ratio of the total area of ​​all grains of the first doping layer 12 per unit area to the total area of ​​all grain gaps; the ratio of the total area of ​​grains of the second doping layer 13 to the total area of ​​grain gaps can be understood as the ratio of the total area of ​​all grains of the second doping layer 13 per unit area to the total area of ​​all grain gaps. Since the ratio of the total area of ​​grains of the first doping layer 12 to the total area of ​​grain gaps per unit area is greater than the ratio of the total area of ​​grains of the second doping layer 13 to the total area of ​​grain gaps, the proportion of grain gaps in the first doping layer 12 is less than the proportion of the total area of ​​grain gaps in the second doping layer 13, and the hollowing degree of the second doping layer 13 is greater than that of the first doping layer 12, which is beneficial to improving the passivation effect of the battery and achieving smaller parasitic absorption of sunlight.

[0061] As an embodiment of the present invention, the ratio of the total area of ​​the grains of the second doping layer 13 to the total area of ​​the gaps between the grains is 2.3% to 32.3%.

[0062] In this embodiment, the ratio of the total area of ​​the grains of the second doping layer 13 to the total area of ​​the gaps between the grains is within a range of 2.3% to 32.3%, so that the hollowing degree of the second doping layer 13 located in the outer layer is more appropriate, which can not only improve the passivation effect of the battery, but also reduce the parasitic absorption of sunlight, thereby improving the utilization efficiency of solar cells for sunlight, thereby improving the battery efficiency.

[0063] In the embodiment of the present invention, since the arrangement of the grains of the doped layer is related to the deposition temperature of the doped layer and the flow rate of the deposition reaction gas, the embodiment of the present invention can control the grain gap area by adjusting the deposition temperature of the doped layer and the flow rate of the deposition reaction gas. The specific type of the reaction gas is not limited and can be determined according to the specific material of the doped layer. For example, if the doped layer is polysilicon, the reaction gas can be silane and nitrogen.

[0064] As an embodiment of the present invention, the deposition temperature of the first doping layer 12 is lower than the deposition temperature of the second doping layer 13 , and the flow rate of the reaction gas introduced during the deposition of the first doping layer 12 is the same as the flow rate of the reaction gas introduced during the deposition of the second doping layer 13 .

[0065] In this embodiment, when the flow rate of the reaction gas introduced during the deposition of the first doping layer 12 is the same as the flow rate of the reaction gas introduced during the deposition of the second doping layer 13, the deposition temperature of the first doping layer 12 is set to be lower than the deposition temperature of the second doping layer 13, so that the total area of ​​the grain gaps of the second doping layer 13 is larger than the total area of ​​the grain gaps of the first doping layer 12, so that the hollowing degree of the second doping layer 13 is greater than that of the first doping layer 12, so that the structure of the second doping layer 13 is looser than that of the first doping layer 12.

[0066] As an embodiment of the present invention, the deposition temperature of the second doping layer 13 is 586-605° C., and the deposition temperature of the first doping layer 12 is 550-585° C.

[0067] In this embodiment, when the flow rate of the reaction gas introduced during the deposition of the first doping layer 12 is the same as the flow rate of the reaction gas introduced during the deposition of the second doping layer 13, the deposition temperature of the second doping layer 13 is 586-605° C., and the deposition temperature of the first doping layer 12 is 550-585° C. Wherein, the deposition temperature of the second doping layer 13 can be any value within the range of 586-605° C., and the deposition temperature of the first doping layer 12 can be any value within the range of 550-585° C., as long as the deposition temperature of the first doping layer 12 is lower than the deposition temperature of the second doping layer 13.

[0068] As another embodiment of the present invention, the deposition temperature of the first doping layer 12 is greater than the deposition temperature of the second doping layer 13 , and the flow rate of the reaction gas introduced during the deposition of the second doping layer 13 is greater than the flow rate of the reaction gas introduced during the deposition of the first doping layer 12 .

[0069] In this embodiment, the flow rate of the reaction gas introduced during the deposition of the second doping layer 13 is greater than the flow rate of the reaction gas introduced during the deposition of the first doping layer 12, and the deposition temperature of the first doping layer 12 is greater than the deposition temperature of the second doping layer 13. Similarly, the total area of ​​the grain gaps in the second doping layer 13 can be greater than the total area of ​​the grain gaps in the first doping layer 12, thereby making the hollowing degree of the second doping layer 13 greater than that of the first doping layer 12, and making the structure of the second doping layer 13 looser than that of the first doping layer 12.

[0070] As an embodiment of the present invention, the deposition temperature of the second doping layer 13 is 585-605° C.; the deposition temperature of the first doping layer 12 is 606-680° C.

[0071] In this embodiment, when the flow rate of the reaction gas introduced during the deposition of the second doping layer 13 is greater than the flow rate of the reaction gas introduced during the deposition of the first doping layer 12, the deposition temperature of the second doping layer 13 is 585-605° C.; the deposition temperature of the first doping layer 12 is 606-680° C. The deposition temperature of the second doping layer 13 can be any value within the range of 585-605° C., and the deposition temperature of the first doping layer 12 can be any value within the range of 606-680° C., as long as the deposition temperature of the first doping layer 12 is less than the deposition temperature of the second doping layer 13.

[0072] As an embodiment of the present invention, the average grain size of the first doping layer 12 is smaller than the average grain size of the second doping layer 13 .

[0073] In this embodiment, the average grain size of the first doping layer 12 and the average grain size of the second doping layer 13 can be specifically measured by XRD, SEM, and TEM methods. Among them, the average grain size of the first doping layer 12 is smaller than the average grain size of the second doping layer 13, which can be understood as the average value of all grain sizes of the first doping layer 12 per unit area is greater than the average value of all grain sizes of the second doping layer 13 per unit area; that is, within a unit area, the grain size in the first doping layer 12 is smaller and the number of grains is greater, compared with the second doping layer 13, so that the density of the first doping layer 12 can be improved, the structure of the first doping layer 12 is more dense, and the passivation effect of the first doping layer 12 is better.

[0074] As an embodiment of the present invention, it also includes:

[0075] The passivation layer 14 is disposed between the first doping layer 12 and the second doping layer 13 .

[0076] In this embodiment, a passivation layer 14 is provided between the first doping layer 12 and the second doping layer 13. The passivation layer 14 can further enhance the passivation effect and block the ablation of the metal paste, thereby reducing the design thickness of the second doping layer 13 and reducing the cost.

[0077] The passivation layer 14 may be one or a combination of silicon oxide, silicon nitride, and silicon carbide. Of course, the passivation layer 14 may not be disposed between the first doped layer 12 and the second doped layer 13, and the first doped layer 12 and the second doped layer 13 may be in direct contact with each other.

[0078] As an embodiment of the present invention, the solar cell passivation contact structure 1 further includes:

[0079] The back passivation film layer 15 is disposed on the side of the doped layer 13 away from the silicon substrate 21 .

[0080] In this embodiment, the electrode of the solar cell contacts the doping layer 13 through the back passivation film layer 15. Among them, the back passivation film layer 15 is used to passivate and protect the back of the doping layer 13, which is beneficial to further improve the efficiency of the battery. Among them, the back passivation film layer 15 can be one or a combination of at least two of silicon nitride, silicon oxynitride, and silicon oxide. For example, the back passivation film layer 15 can be sequentially stacked on aluminum oxide and silicon nitride on the doping layer 13, which can achieve a good passivation effect on the back of the doping layer and have a good protection function for the doping layer.

[0081] Embodiment 2

[0082] Please refer to Figure 4This embodiment provides a solar cell 2, including a silicon substrate 21, the silicon substrate 21 includes a light-facing surface 211 and a backlight surface 212 arranged opposite to the light-facing surface 211, and the backlight surface 212 is provided with the solar cell passivation contact structure 1 of the above-mentioned embodiment 1.

[0083] In the embodiment of the present invention, the solar cell is a back-contact solar cell, and the backlight surface 212 of the back-contact solar cell is provided with a P region 213 and an N region 214, and both the P region 213 and the N region 214 are provided with a solar cell passivation contact structure 1; the second doping layer 13 of the P region 213 is a P-type doping layer, and the second doping layer 13 of the N region 214 is an N-type doping layer.

[0084] As an embodiment of the present invention, the solar cell 2 further includes:

[0085] A first electrode 25 disposed in the P region 213 , the first electrode 25 is in contact with the second doping layer 13 in the P region 213 ;

[0086] The second electrode 26 is disposed in the N region 214 , and the second electrode 26 is in contact with the second doping layer 13 in the N region 214 .

[0087] In this embodiment, the first electrode 25 contacts the second doping layer 13 of the P region 213 to form an ohmic contact, and the second electrode 26 contacts the second doping layer 13 of the N region 214 to achieve current extraction of the solar cell. Specifically, the first electrode 25 contacts the second doping layer 13 through the back passivation film layer 15 at the position of the P region 213, and the second electrode 26 contacts the second doping layer 13 through the back passivation film layer 15 at the position of the N region 214.

[0088] In this embodiment, there are multiple P regions 213 and multiple N regions 214, and multiple P regions 213 and multiple N regions 214 are alternately arranged in sequence. Among them, an isolation region 215 is arranged between adjacent P regions 213 and N regions 214. The isolation region 215 can be a groove or a gap, so that the P region 213 and the N region 214 are well isolated.

[0089] in, Figure 4 The P region 213 and the N region 214 of the back contact solar cell shown in the figure are both provided with the solar cell passivation contact structure of the above-mentioned embodiment 1. Of course, in some other embodiments, only one of the P region 213 and the N region 214 may be provided with the solar cell passivation contact structure of the above-mentioned embodiment 1. For example, only the P region 213 is provided with the solar cell passivation contact structure of the above-mentioned embodiment 1, and the N region 214 is provided with other existing conventional solar cell passivation contact structures; or, only the N region 214 is provided with the solar cell passivation contact structure of the above-mentioned embodiment 1, and the P region 213 is provided with other existing conventional solar cell passivation contact structures.

[0090] The present embodiment provides a solar cell using the solar cell passivation contact structure. Since the solar cell passivation contact structure is provided with a first doping layer 12 and a second doping layer 13, within a unit area, the total area of ​​the grain gaps of the second doping layer 13 is greater than the total area of ​​the grain gaps of the first doping layer 12, so that the hollowing degree of the second doping layer 13 located in the outer layer is greater than the hollowing degree of the first doping layer 12 located in the inner layer. The first doping layer 12 and the second doping layer 13 can be used to improve the passivation effect of the cell and reduce the parasitic absorption of sunlight, thereby improving the utilization efficiency of the solar cell for sunlight, thereby improving the cell efficiency.

[0091] Embodiment 3

[0092] Please refer to Figure 5 This embodiment provides a solar cell 2, including a silicon substrate 21, the silicon substrate 21 includes a light-facing surface 211, and a backlight surface 212 arranged opposite to the light-facing surface 211, and the light-facing surface 211 and / or the backlight surface 212 are both provided with the solar cell passivation contact structure of the above-mentioned embodiment 1.

[0093] As an embodiment of the present invention, the solar cell 2 is a double-sided contact solar cell, one of the light-facing surface 211 and the backlight surface 212 is provided with a P region 213, and the other is provided with an N region 214, and both the P region 213 and the N region 214 are provided with a solar cell passivation contact structure; the second doping layer 13 of the P region 213 is a P-type doping layer, and the second doping layer 13 of the N region 214 is an N-type doping layer. Among them, Figure 5 2 only illustrates the situation where the P region 213 is disposed on the light-facing surface 211 and the N region 214 is disposed on the backlight surface 212. Of course, the P region 213 may also be disposed on the backlight surface 212 and the N region 214 may be disposed on the light-facing surface 211.

[0094] As an embodiment of the present invention, the solar cell 2 further includes:

[0095] A first electrode 25 disposed in the P region 213 , the first electrode 25 is in contact with the second doping layer 13 in the P region 213 ;

[0096] The second electrode 26 is disposed in the N region 214 , and the second electrode 26 is in contact with the second doping layer 13 in the N region 214 .

[0097] In this embodiment, the first electrode 25 contacts the second doping layer 13 of the P region 213 to form an ohmic contact, and the second electrode 26 contacts the second doping layer 13 of the N region 214 to achieve current extraction of the solar cell. Specifically, the first electrode 25 contacts the second doping layer 13 through the back passivation film layer 15 at the position of the P region 213, and the second electrode 26 contacts the second doping layer 13 through the back passivation film layer 15 at the position of the N region 214.

[0098] In this embodiment, the number of P regions 213 and N regions 214 are both multiple, and multiple P regions 213 are alternately arranged on the light-facing surface 211, and multiple N regions 214 are alternately arranged on the backlight surface 212; or multiple N regions 214 are alternately arranged on the light-facing surface 211, and multiple P regions 213 are alternately arranged on the backlight surface 212. Figure 5 Schematically, the plurality of P regions 213 are sequentially and alternately arranged at intervals on the light-facing surface 211 , and the plurality of N regions 214 are sequentially and alternately arranged at intervals on the backlight surface 212 .

[0099] in, Figure 5 The P region 213 and the N region 214 of the back contact solar cell shown in the figure are both provided with the solar cell passivation contact structure of the above-mentioned embodiment 1. Of course, in some other embodiments, only one of the P region 213 and the N region 214 may be provided with the solar cell passivation contact structure of the above-mentioned embodiment 1. For example, only the P region 213 is provided with the solar cell passivation contact structure of the above-mentioned embodiment 1, and the N region 214 is provided with other existing conventional solar cell passivation contact structures; or, only the N region 214 is provided with the solar cell passivation contact structure of the above-mentioned embodiment 1, and the P region 213 is provided with other existing conventional solar cell passivation contact structures.

[0100] Among them, the P region 213 may completely cover the light-facing surface 211 of the silicon substrate 211, or may only cover a part of the light-facing surface 211 of the silicon substrate 211; the N region 214 may completely cover the backlight surface of the silicon substrate 211, or may only cover a part of the backlight surface 212 of the silicon substrate 211. Preferably, the P region 213 covers a part of the light-facing surface 211 of the silicon substrate 211, and two adjacent P regions 213 are arranged at intervals, so that the doping layer of the light-facing surface 211 only covers a part of the light-facing surface 211 of the silicon substrate 211; the N region 214 only covers a part of the backlight surface 212 of the silicon substrate 211, and two adjacent N regions 214 are arranged at intervals, so that the doping layer of the backlight surface 212 only covers a part of the light-facing surface 211 of the silicon substrate 211, which can reduce light parasitic absorption.

[0101] A solar cell provided in the present embodiment applies the solar cell passivation contact structure. Since the solar cell passivation contact structure is provided with a first doping layer 12 and a second doping layer 13, within a unit area, the total area of ​​the grain gaps of the second doping layer 13 is greater than the total area of ​​the grain gaps of the first doping layer 12, so that the hollowing degree of the second doping layer 13 located in the outer layer is greater than the hollowing degree of the first doping layer 12 located in the inner layer. While the first doping layer 12 and the second doping layer 13 are used to improve the passivation effect of the cell, the parasitic absorption of sunlight can be reduced, and the utilization efficiency of sunlight by the solar cell is improved, thereby improving the cell efficiency.

[0102] Embodiment 4

[0103] The embodiment of the present invention further provides a battery assembly, which includes the solar cell of the above embodiment 2 or embodiment 3. It should be noted that the battery assembly has the same or similar beneficial effects as the above solar cell 2, and the relevant parts between the two can be referenced to each other. In order to avoid repetition, it will not be repeated here.

[0104] In this embodiment, multiple solar cells 2 in the battery assembly can be connected in series in sequence to form a battery string, thereby realizing the series bus output of current. For example, the series connection of battery cells can be realized by setting welding strips (bus bars, interconnecting strips), conductive backplanes, etc.

[0105] It is understandable that in such an embodiment, the battery assembly may further include a metal frame, a back plate, photovoltaic glass and an adhesive film. The adhesive film may be filled between the front and back of the solar cell 2 and the photovoltaic glass, adjacent cells, etc. As a filler, it may be a transparent colloid with good light transmission and aging resistance. For example, the adhesive film may be an EVA adhesive film or a POE adhesive film. The specific selection may be based on actual conditions and is not limited here.

[0106] Photovoltaic glass can cover the adhesive film on the front of the solar cell 2. The photovoltaic glass can be ultra-white glass, which has high light transmittance, high transparency, and excellent physical, mechanical and optical properties. For example, the light transmittance of ultra-white glass can reach more than 92%, which can protect the solar cell without affecting the efficiency of the solar cell as much as possible. At the same time, the adhesive film can bond the photovoltaic glass and the solar cell 2 together. The presence of the adhesive film can seal and insulate the solar cell 2 and make it waterproof and moisture-proof.

[0107] The back panel can be attached to the adhesive film on the back of the solar cell 2. The back panel can protect and support the solar cell 2 and has reliable insulation, water resistance and aging resistance. There are multiple options for the back panel, which can usually be tempered glass, organic glass, aluminum alloy TPT composite adhesive film, etc. It can be set according to specific circumstances and is not limited here. The whole composed of the back panel, solar cell 2, adhesive film and photovoltaic glass can be set on a metal frame. The metal frame serves as the main external support structure of the entire solar cell assembly and can stably support and install the solar cell assembly. For example, the solar cell assembly can be installed at the required location through the metal frame.

[0108] Embodiment 5

[0109] The embodiment of the present invention further provides a photovoltaic system, which includes the battery assembly of the above-mentioned embodiment 4. It should be noted that the photovoltaic system and the solar cell 2 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 described here.

[0110] In this embodiment, the photovoltaic system can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple solar cell modules. For example, multiple solar cell modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid, and then connected to the mains network to realize solar power supply.

[0111] 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 passivation contact structure, characterized in that: include: A tunneling layer disposed on the surface of the silicon substrate; A first doped layer, disposed on a side of the tunneling layer away from the silicon substrate; A second doping layer, disposed on a side of the first doping layer away from the silicon substrate, the second doping layer having the same doping type as the first doping layer; In a unit area, the total area of ​​the grain gaps of the second doping layer is greater than the total area of ​​the grain gaps of the first doping layer.

2. The solar cell passivation contact structure according to claim 1, characterized in that: The first doping layer and the second doping layer are an integrally formed structure or a separately formed structure.

3. The solar cell passivation contact structure according to claim 1, characterized in that: The ratio of the total area of ​​the grain gaps of the second doping layer to the total area of ​​the grain gaps of the first doping layer is 6-10.

4. The solar cell passivation contact structure according to claim 1, characterized in that: In a unit area, the ratio of the area occupied by the grains of the first doping layer to the area occupied by the gaps between the grains is greater than the ratio of the area occupied by the grains of the second doping layer to the area occupied by the gaps between the grains.

5. The solar cell passivation contact structure according to claim 1, characterized in that: The ratio of the total area of ​​the grains of the second doping layer to the total area of ​​the gaps between the grains is 2.3% to 32.3%.

6. The solar cell passivation contact structure according to claim 1, characterized in that: The deposition temperature of the first doping layer is lower than the deposition temperature of the second doping layer, and the flow rate of the reaction gas introduced during the deposition of the first doping layer is the same as the flow rate of the reaction gas introduced during the deposition of the second doping layer.

7. The solar cell passivation contact structure according to claim 6, characterized in that: The deposition temperature of the second doping layer is 586-605°C, and the deposition temperature of the first doping layer is 550-585°C.

8. The solar cell passivation contact structure according to claim 1, characterized in that: The deposition temperature of the first doping layer is greater than the deposition temperature of the second doping layer, and the flow rate of the reaction gas introduced during the deposition of the second doping layer is greater than the flow rate of the reaction gas introduced during the deposition of the first doping layer.

9. The solar cell passivation contact structure according to claim 8, characterized in that: The deposition temperature of the second doping layer is 585-605°C; the deposition temperature of the first doping layer is 606-680°C.

10. The solar cell passivation contact structure according to claim 1, characterized in that: Also includes: The passivation layer is disposed between the first doping layer and the second doping layer.

11. The solar cell passivation contact structure according to claim 1, characterized in that: An average grain size of the first doping layer is smaller than an average grain size of the second doping layer.

12. The solar cell passivation contact structure according to claim 1, characterized in that: The first doping layer and / or the second doping layer is one of doped polycrystalline silicon, doped microcrystalline silicon, doped nanocrystalline silicon, and doped amorphous silicon, or a combination of at least two of them.

13. A solar cell, characterized in that: The invention comprises a silicon substrate, wherein the silicon substrate comprises a light-facing surface and a backlight surface arranged opposite to the light-facing surface, and the solar cell passivation contact structure according to any one of claims 1 to 12 is arranged on the light-facing surface and / or the backlight surface.

14. The solar cell according to claim 13, characterized in that: The solar cell is a back-contact solar cell, the backlight surface is provided with a P region and an N region, and the P region and the N region are both provided with the solar cell passivation contact structure; the second doping layer in the P region is a P-type doping layer, and the second doping layer in the N region is an N-type doping layer.

15. The solar cell according to claim 13, characterized in that: The solar cell is a double-sided contact solar cell, one of the light-facing surface and the backlight surface is provided with a P region, and the other is provided with an N region, and both the P region and the N region are provided with the solar cell passivation contact structure; the second doping layer in the P region is a P-type doping layer, and the second doping layer in the N region is an N-type doping layer.

16. A battery assembly, characterized in that: Comprising the solar cell according to any one of claims 1 to 15.

17. A photovoltaic system, characterized in that: Comprising the battery assembly as claimed in claim 16.

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