Solar cell, cell assembly and photovoltaic system

Abstract

The invention is suitable for the technical field of solar cells, and provides a solar cell, a cell assembly and a photovoltaic system, the solar cell comprises a silicon substrate, the surface of which is provided with a P region and an N region; the first passivation layer is located in the P region and arranged on the surface of the silicon substrate; the second passivation layer is located in the N region and arranged on the surface of the silicon substrate; the P-type doping layer is arranged on one surface, deviating from the silicon substrate, of the first passivation layer; the N-type doping layer is arranged on one surface, deviating from the silicon substrate, of the second passivation layer; the resistance of the first passivation layer is smaller than that of the second passivation layer. According to the solar cell, the current transmission effect of the P region can be improved, the problem that the current transmission effect of the P region of a traditional solar cell is poor can be solved, and the cell efficiency is effectively improved.

Description

Technical Field

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

[0002] As fossil fuels are becoming less and less, solar energy has become the most common and clean renewable energy. Among them, solar cells are devices that use the photovoltaic effect to directly convert light energy into electrical energy. Solar cells mainly include double-sided solar cells and back-contact solar cells.

[0003] In the prior art, a bifacial solar cell has a P region on one side of its silicon substrate and an N region on the other side; a back contact solar cell has both a P region and an N region on its back side; wherein, for the purpose of cell passivation, the P region of the bifacial solar cell and the back contact solar cell is provided with a first passivation layer and a P-type doping layer provided on the first passivation layer, and the electrode of the P region is in contact with the P-type doping layer; the N region of the bifacial solar cell and the back contact solar cell is provided with a second passivation layer and an N-type doping layer provided on the second passivation layer, and the electrode of the N region is in contact with the N-type doping layer. However, the first passivation layer of the P region and the second passivation layer of the N region of a conventional solar cell are prepared and formed at the same time, the first passivation layer of the P region and the second passivation layer of the N region have the same resistance, and the P-type doping layer of the P region has a greater resistance than the N-type doping layer of the N region, which makes the P-type doping layer poorly conductive, resulting in poor current transmission in the P region and low cell efficiency. Summary of the invention

[0004] The present invention provides a solar cell, aiming to solve the problems of poor current transmission effect in the P region and low cell efficiency in the solar cell of the prior art.

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

[0006] A silicon substrate, wherein a P region and an N region are provided on the surface of the silicon substrate;

[0007] A first passivation layer, located in the P region and disposed on the surface of the silicon substrate;

[0008] A second passivation layer, located in the N region and disposed on the surface of the silicon substrate;

[0009] A P-type doped layer, disposed on a side of the first passivation layer away from the silicon substrate;

[0010] An N-type doped layer, disposed on a side of the second passivation layer away from the silicon substrate;

[0011] The resistance of the first passivation layer is smaller than the resistance of the second passivation layer.

[0012] Preferably, the first passivation layer contains a P-type dopant, the second passivation layer contains an N-type dopant, and the doping concentration of the P-type dopant in the first passivation layer is greater than the doping concentration of the N-type dopant in the second passivation layer.

[0013] Preferably, the doping concentration of the P-type dopant in the first passivation layer is 1×10 19 ~8×10 21 atoms / cm 3 The doping concentration of the N-type dopant in the second passivation layer is 5×10 18 ~5×10 21 atoms / cm 3 .

[0014] Preferably, a ratio of the resistance of the first passivation layer to the resistance of the second passivation layer is 0.2-1.

[0015] Preferably, both the first passivation layer and the second passivation layer are porous passivation layers, and the hole density of the first passivation layer is greater than the hole density of the second passivation layer.

[0016] Preferably, both the first passivation layer and the second passivation layer are porous passivation layers, and the average pore size of the holes in the first passivation layer is larger than the average pore size of the holes in the second passivation layer.

[0017] Preferably, the thickness of the first passivation layer is smaller than the thickness of the second passivation layer.

[0018] Preferably, a rate of change of the resistance of the first passivation layer with temperature change is greater than a rate of change of the resistance of the second passivation layer with temperature change.

[0019] Preferably, the resistance of the first passivation layer is 200Ω to 5000Ω; the resistance of the second passivation layer is 1000Ω to 25000Ω.

[0020] Preferably, the contact resistance of the first passivation layer is smaller than the contact resistance of the second passivation layer.

[0021] Preferably, the contact resistance of the first passivation layer is 0.2 to 5 mΩ·cm 2 .

[0022] Preferably, the contact resistance of the second passivation layer is 1 to 25 mΩ·cm 2

[0023] Preferably, the resistivity of the first passivation layer is smaller than the resistivity of the second passivation layer.

[0024] Preferably, the resistivity of the first passivation layer is 500 Ω·cm to 10000 Ω·cm, and the resistivity of the second passivation layer is 2000 Ω·cm to 40000 Ω·cm.

[0025] Preferably, the resistance of the N-type doped layer is smaller than the resistance of the P-type doped layer.

[0026] Preferably, the bandgap width of the first passivation layer is smaller than the bandgap width of the second passivation layer.

[0027] Preferably, the bandgap width of the P-type doping layer is smaller than the bandgap width of the N-type doping layer.

[0028] Preferably, the dielectric constant of the first passivation layer is smaller than the dielectric constant of the second passivation layer.

[0029] Preferably, the solar cell is a back-contact solar cell, and the P region and the N region are located on the same surface of the silicon substrate.

[0030] Preferably, the solar cell is a double-sided solar cell, and the P region and the N region are respectively located on two opposite sides of the silicon substrate.

[0031] The present invention also provides a battery assembly, comprising the above-mentioned solar cell.

[0032] The present invention also provides a photovoltaic system, comprising the above-mentioned battery assembly.

[0033] A solar cell provided by the present invention sets the resistance of the first passivation layer to be smaller than the resistance of the second passivation layer. Compared with the resistance of the second passivation layer, by reducing the resistance of the first passivation layer, the conductive effect of the first passivation layer can be improved, thereby improving the current transmission effect of the P region, achieving a balance between the current transmission effects of the P region and the N region, and solving the problem of poor current transmission effect in the P region of a traditional solar cell, so that both the P region and the N region of the solar cell can achieve good current transmission effects, thereby effectively improving the battery efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of a solar cell provided by an embodiment of the present invention;

[0035] Figure 2 A schematic diagram of another solar cell provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0036] 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.

[0037] A solar cell provided by an embodiment of the present invention sets the resistance of the first passivation layer to be smaller than the resistance of the second passivation layer. Compared with the resistance of the second passivation layer, by reducing the resistance of the first passivation layer, the conductive effect of the first passivation layer can be improved, thereby improving the current transmission effect of the P region, achieving a balance between the current transmission effects of the P region and the N region, and solving the problem of poor current transmission effect in the P region of a traditional solar cell, so that both the P region and the N region of the solar cell can achieve good current transmission effects, thereby effectively improving the battery efficiency.

[0038] Please refer to Figure 1 and Figure 2 , a solar cell provided by an embodiment of the present invention comprises:

[0039] A silicon substrate 1, wherein a P region 11 and an N region 12 are provided on the surface of the silicon substrate 1;

[0040] A first passivation layer 2, located in the P region 11 and disposed on the surface of the silicon substrate 1;

[0041] The second passivation layer 3 is located in the N region 12 and is disposed on the surface of the silicon substrate 1;

[0042] A P-type doped layer 4 is provided on a side of the first passivation layer 2 facing away from the silicon substrate 1;

[0043] An N-type doped layer 5 is disposed on a side of the second passivation layer 3 facing away from the silicon substrate 1;

[0044] The resistance of the first passivation layer 2 is smaller than the resistance of the second passivation layer 3 .

[0045] In the embodiment of the present invention, the solar cell provided has a resistance of the first passivation layer 2 that is smaller than the resistance of the second passivation layer 3. It can be understood that, under the premise that the resistance of the second passivation layer 3 remains unchanged, the resistance of the first passivation layer 2 is reduced, and the conductive effect of the first passivation layer 2 is improved, thereby improving the current transmission effect of the P region 11, achieving a balance between the current transmission effects of the P region 11 and the N region 12, and solving the problem of poor current transmission effect of the P region 11 of a traditional solar cell. This allows both the P region 11 and the N region 12 of the solar cell to achieve good current transmission effects, thereby effectively improving the battery efficiency.

[0046] In the embodiment of the present invention, the resistance of the first passivation layer 2 and the second passivation layer 3 can be measured by a spreading resistance profile (SRP). Of course, the resistance test is not limited to this measurement method, and other methods can also be used to directly or indirectly measure.

[0047] In the embodiment of the present invention, the P-type doped layer 4 is electrically connected to the silicon substrate 1 through the first passivation layer 2, and the N-type doped layer 5 is electrically connected to the silicon substrate 1 through the second passivation layer 3. Therefore, by reducing the resistance of the first passivation layer 2, the conductive effect of the first passivation layer 2 is improved, and the current transmission effect of the P region 11 can be improved, so that the current transmission effect of the P region 11 and the N region 12 can be balanced.

[0048] In the embodiment of the present invention, the silicon substrate 1 may be a P-type silicon substrate 1 or an N-type silicon substrate 1. The surface of the silicon substrate 1 may be the backlight surface or the light-facing surface of the solar cell.

[0049] Please refer to Figure 1 As an embodiment of the invention, the solar cell is a back contact solar cell, and the P region 11 and the N region 12 are located on the same surface of the silicon substrate 1. The silicon substrate 1 includes a front surface 101 and a back surface 102 opposite to the front surface 101. The front surface 101 of the silicon substrate 1 is the light-facing surface of the back contact solar cell, and the back surface 102 of the silicon substrate 1 is the backlight surface of the back contact solar cell. The P region 11 and the N region 12 are both located on the back surface 102 of the silicon substrate 1.

[0050] There are multiple P regions 11 and multiple N regions 12, which are alternately arranged in sequence, and an isolation region 13 is arranged between adjacent P regions 11 and N regions 12. The isolation region 13 may be a groove or a gap.

[0051] Please refer to Figure 2 As another embodiment of the invention, the solar cell is a bifacial solar cell, and the P region 11 and the N region 12 are respectively located on two opposite sides of the silicon substrate 1. The silicon substrate 1 includes a front side 101 and a back side 102 opposite to the front side 101. The front side 101 of the silicon substrate 1 is the light-facing side of the bifacial solar cell, and the back side 102 of the silicon substrate 1 is the backlight side of the bifacial solar cell. One of the P region 11 and the N region 12 is located on the front side 101 of the silicon substrate 1, and the other is located on the back side 102 of the silicon substrate 1.

[0052] in, Figure 2 The P region 11 shown in the figure is located on the front side 101 of the silicon substrate 1, and the N region 12 is located on the back side 102 of the silicon substrate 1. The P region 11 may completely cover the front side 101 of the silicon substrate 1, or may only cover a part of the front side 101 of the silicon substrate 1; the N region 12 may completely cover the back side 102 of the silicon substrate 1, or may only cover a part of the back side 102 of the silicon substrate 1. There may also be multiple P regions 11 and N regions 12. Preferably, the P region 11 covers a part of the front side 101 of the silicon substrate 1, and two adjacent P regions 11 are spaced apart from each other; the N region 12 only covers a part of the back side 102 of the silicon substrate 1, and two adjacent N regions 12 are spaced apart from each other, which can reduce light parasitic absorption.

[0053] In the embodiment of the present invention, the doping polarities of the P-type doping layer 4 and the N-type doping layer 5 are opposite. The P-type doping layer 4 is a P-type doped polysilicon containing a P-type dopant, and the N-type doping layer 5 is an N-type doped polysilicon containing an N-type dopant. 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.

[0054] As an embodiment of the present invention, the solar cell further comprises:

[0055] A first electrode 6, disposed in the P region 11 and in contact with the P-type doped layer 4;

[0056] The second electrode 7 is disposed in the N region 12 and in contact with the N-type doped layer 5 .

[0057] In this embodiment, the first electrode 6 contacts the P-type doping layer 4 to form an ohmic contact, and the second electrode 7 contacts the N-type doping layer 5 to form an ohmic contact. Preferably, the depth of the first electrode 6 entering the P-type doping layer 4 is greater than the depth of the second electrode 7 entering the N-type doping layer 5, which can increase the contact area between the first electrode 6 and the P-type doping layer 4, further improve the conductivity of the P region 11, and improve the battery efficiency.

[0058] As an embodiment of the present invention, the first passivation layer 2 contains a P-type dopant, the second passivation layer 3 contains an N-type dopant, and the doping concentration of the P-type dopant in the first passivation layer 2 is greater than the doping concentration of the N-type dopant in the second passivation layer 3 .

[0059] In this embodiment, since the doping concentration of the P-type dopant of the first passivation layer 2 is greater than the doping concentration of the N-type dopant of the second passivation layer 3, that is, by increasing the doping concentration of the P-type dopant of the first passivation layer 2, the resistance of the first passivation layer 2 is reduced, and the conductivity of the first passivation layer 2 is further improved, the current transmission effect of the P region 11 can be improved, thereby improving the battery efficiency.

[0060] As an embodiment of the present invention, the doping concentration of the P-type dopant in the first passivation layer 2 is 1×10 19 ~8×10 21 atoms / cm 3 The doping concentration of the N-type dopant in the second passivation layer 3 is 5×10 18 ~5×10 21 atoms / cm 3 .

[0061] In this embodiment, the doping concentrations of the first passivation layer 2 and the second passivation layer 3 can be set according to actual needs, as long as the doping concentration of the P-type dopant in the first passivation layer 2 is greater than the doping concentration of the N-type dopant in the second passivation layer 3 .

[0062] Among them, the doping concentration of the P-type dopant is the average value or peak value of the doping concentration of the P-type dopant, and the doping concentration of the N-type dopant is the average value or peak value of the doping concentration of the N-type dopant; wherein the peak value is the maximum doping concentration value. When comparing the doping concentrations, the comparison is made at the same time with the average value of the doping concentration or at the same time with the peak value of the doping concentration. It can be understood that the average value of the doping concentration of the P-type dopant in any area of ​​the first passivation layer 2 is greater than the average value of the doping concentration of the N-type dopant in any area of ​​the second passivation layer 3; it can also be that the peak value of the doping concentration of the P-type dopant in any area of ​​the first passivation layer 2 is greater than the peak value of the doping concentration of the N-type dopant in any area of ​​the second passivation layer 3.

[0063] In the embodiment of the present invention, the doping concentration of the P-type dopant may be the doping concentration of the activated P-type dopant, and the doping concentration of the N-type dopant may be the doping concentration of the activated N-type dopant, and the doping concentrations of the activated P-type dopant and the N-type dopant may be measured by a spreading resistance profile (SRP) or an electrochemical capacitance-voltage method (ECV). Of course, the doping concentration of the P-type dopant may also be the sum of the doping concentration of the activated P-type dopant and the doping concentration of the inactivated P-type dopant, and the doping concentration of the N-type dopant may also be the sum of the doping concentration of the activated N-type dopant and the doping concentration of the inactivated N-type dopant, and may be measured by secondary ion mass spectrometry (SIMS).

[0064] As an embodiment of the present invention, the ratio of the resistance of the first passivation layer 2 to the resistance of the second passivation layer 3 is 0.2-1.

[0065] In this embodiment, the ratio of the resistance of the first passivation layer 2 to the resistance of the second passivation layer 3 may be 0.2, or 0.3, or 0.4, or 0.5, or 0.6, or 0.7, or 0.8, or 0.9, or 1.0.

[0066] In this embodiment, the ratio of the resistance of the first passivation layer 2 to the resistance of the second passivation layer 3 is 0.2 to 1, which can not only achieve a good conductive effect of the first passivation layer 2, achieve a balanced current transmission effect between the P region 11 and the N region 12, but also facilitate the processing and preparation of the first passivation layer 2 and the second passivation layer 3.

[0067] As an embodiment of the present invention, the resistance of the first passivation layer 2 is 200Ω to 5000Ω, and the resistance of the second passivation layer 3 is 1000Ω to 25000Ω. The specific resistance values ​​of the first passivation layer 2 and the second passivation layer 3 can be flexibly set according to actual conditions.

[0068] In this embodiment, the resistance of the first passivation layer 2 and the second passivation layer 3 can be set according to actual needs, and it only needs to satisfy that the resistance of the first passivation layer 2 is smaller than the resistance of the second passivation layer 3 .

[0069] As an embodiment of the present invention, the contact resistance of the first passivation layer 2 is smaller than the contact resistance of the second passivation layer 3 . By reducing the contact resistance of the first passivation layer 2 , the current transmission effect of the P region 11 can be improved.

[0070] As an embodiment of the present invention, the contact resistance of the first passivation layer 2 is 0.2 to 5 mΩ·cm 2 .

[0071] The contact resistance of the first passivation layer 2 may be any value within the above range and may be set according to actual conditions.

[0072] As an embodiment of the present invention, the contact resistance of the second passivation layer 3 is 1 to 25 mΩ·cm 2 .

[0073] The contact resistance of the second passivation layer 3 may be any value within the above range and may be set according to actual conditions.

[0074] As an embodiment of the present invention, the resistivity of the first passivation layer 2 is smaller than the resistivity of the second passivation layer 3 .

[0075] In this embodiment, by reducing the resistivity of the first passivation layer 2 , the current transmission effect of the P region 11 can be improved, thereby improving the battery efficiency.

[0076] As an embodiment of the present invention, the resistivity of the first passivation layer 2 is 500 Ω·cm to 10000 Ω·cm, and the resistivity of the second passivation layer 3 is 2000 Ω·cm to 40000 Ω·cm.

[0077] The resistivity of the first passivation layer 2 and the second passivation layer 3 may be any value within the above range and may be set according to actual conditions.

[0078] As an embodiment of the present invention, both the first passivation layer 2 and the second passivation layer 3 are porous passivation layers, and the hole density of the first passivation layer 2 is greater than the hole density of the second passivation layer 3 .

[0079] In this embodiment, the holes on the first passivation layer 2 vertically penetrate the first passivation layer 2, and the holes on the second passivation layer 3 vertically penetrate the second passivation layer 3. Among them, the P-type doped layer 4 contacts the silicon substrate 1 using the holes on the first passivation layer 2, and the N-type doped layer 5 contacts the silicon substrate 1 using the holes on the second passivation layer 3, which is beneficial to reduce current loss and improve battery conversion efficiency. Since the hole density of the first passivation layer 2 is greater than the hole density of the second passivation layer 3, that is, the number of holes per unit area of ​​the first passivation layer 2 is greater than the number of holes per unit area of ​​the second passivation layer 3, the resistance of the first passivation layer 2 can be reduced, so that the resistance of the first passivation layer 2 is less than the resistance of the second passivation layer 3, the conductivity of the first passivation layer 2 is improved, and the conductivity effect of the P region 11 is improved, and the implementation method is simple.

[0080] The holes of the first passivation layer 2 and the second passivation layer 3 can be prepared by chemical corrosion, dry etching or thermal diffusion impact, etc., which are prepared according to actual use needs and are not specifically limited here. When the first passivation layer 2 and the second passivation layer 3 are observed from a top view angle, the first passivation layer 2 and the second passivation layer 3 present a porous structure, and when the first passivation layer 2 and the second passivation layer 3 are observed from a cross-sectional angle, the first passivation layer 2 and the second passivation layer 3 show a multi-channel structure.

[0081] As an embodiment of the present invention, the first passivation layer 2 and the second passivation layer 3 are both porous passivation layers, and the average pore size of the pores of the first passivation layer 2 is greater than the average pore size of the pores of the second passivation layer 3 .

[0082] In this embodiment, the apertures of the holes in the first passivation layer 2 may be equal or unequal; similarly, the apertures of the holes in the second passivation layer 3 may be equal or unequal. The average aperture of the holes in the first passivation layer 2 may be understood as the average aperture of all holes in the first passivation layer 2 or the average aperture of all holes in a unit area; the average aperture of the holes in the second passivation layer 3 may be understood as the average aperture of all holes in the second passivation layer 3 or the average aperture of all holes in a unit area. By setting the average aperture of the holes in the first passivation layer 2 to be larger than the average aperture of the holes in the second passivation layer 3, the resistance of the first passivation layer 2 may also be reduced, so that the resistance of the first passivation layer 2 is smaller than the resistance of the second passivation layer 3, the conductivity of the first passivation layer 2 is improved, and the conductivity effect of the P region 11 is improved, and the implementation method is simple.

[0083] As an optional embodiment of the present invention, the hole diameters of the first passivation layer 2 and the second passivation layer 3 are less than 10 um, and the average hole diameter of the first passivation layer 2 and the second passivation layer 3 is greater than the average hole diameter of the second passivation layer 3 .

[0084] As an embodiment of the present invention, the thickness of the first passivation layer 2 is smaller than the thickness of the second passivation layer 3 .

[0085] In this embodiment, the thickness of the first passivation layer 2 is less than the thickness of the second passivation layer 3, that is, by thinning the thickness of the first passivation layer 2, it is beneficial to the setting of holes, which is beneficial to improving the tunneling effect of the first passivation layer 2, improving the conductive effect of the P region 11, and further improving the battery transmission effect of the P region 11.

[0086] As an embodiment of the present invention, the rate of change of the resistance of the first passivation layer 2 with temperature change is greater than the rate of change of the resistance of the second passivation layer 3 with temperature change.

[0087] In this embodiment, under the same temperature change value, the resistance change value of the first passivation layer 2 is greater than the resistance change value of the second passivation layer 3, that is, the rate of change of the resistance of the first passivation layer 2 with temperature change is greater than the rate of change of the resistance of the second passivation layer 3 with temperature change, so that the speed of change of the resistance of the first passivation layer 2 with temperature change is faster than the speed of change of the resistance of the second passivation layer 3 with temperature change, which can make the conductive performance improve faster, facilitate the rapid improvement of the conductive performance of the first passivation layer 2 in the P region 11, and can improve production efficiency.

[0088] As an embodiment of the present invention, the resistance of the N-type doped layer 5 is smaller than the resistance of the P-type doped layer 4 .

[0089] In this embodiment, the doping concentration of the N dopant of the N-type doping layer 5 is greater than the doping concentration of the P-type dopant of the P-type doping layer 4, so that the resistance of the N-type doping layer 5 is less than the resistance of the P-type doping layer 4, thereby improving the conductivity of the entire P region 11 and balancing the conductivity effects of the P region 11 and the N region 12.

[0090] As an embodiment of the present invention, the band gap width of the first passivation layer 2 is smaller than the band gap width of the second passivation layer 3 .

[0091] In this embodiment, by reducing the bandgap width of the first passivation layer 2, so that the bandgap width of the first passivation layer 2 is smaller than the bandgap width of the second passivation layer 3, the conductivity of the first passivation layer 2 can be improved, thereby improving the conductivity of the P region 11. Of course, in some other embodiments, the bandgap width of the first passivation layer 2 can also be greater than or equal to the bandgap width of the second passivation layer 3.

[0092] As an embodiment of the present invention, the bandgap width of the P-type doping layer 4 is smaller than the bandgap width of the N-type doping layer 5 .

[0093] In this embodiment, by reducing the bandgap width of the P-type doping layer 4, so that the bandgap width of the P-type doping layer 4 is smaller than the bandgap width of the N-type doping layer 5, the conductivity of the P-type doping layer 4 can be improved, and thus the conductivity of the P region 11 can also be improved. Of course, in some other embodiments, the bandgap width of the P-type doping layer 4 can also be greater than or equal to the bandgap width of the N-type doping layer 5.

[0094] As an embodiment of the present invention, the dielectric constant of the first passivation layer 2 is smaller than the dielectric constant of the second passivation layer 3 .

[0095] In this embodiment, the preparation process of the first passivation layer 2 and the second passivation layer 3 can be adjusted to reduce the dielectric constant of the first passivation layer 2, so that the dielectric constant of the first passivation layer 2 is smaller than the dielectric constant of the second passivation layer 3, which can improve the conductivity of the first passivation layer 2 and the conductivity of the P region 11. Of course, in some other embodiments, the dielectric constant of the first passivation layer 2 can also be greater than or equal to the dielectric constant of the second passivation layer 3.

[0096] As an embodiment of the present invention, the materials of the first passivation layer 2 and the second passivation layer 3 may be the same or different. For example, the first passivation layer 2 and the second passivation layer 3 may be one or a combination of silicon oxide, silicon oxynitride, and silicon nitride, respectively. When the materials of the first passivation layer 2 and the second passivation layer 3 are different, the material resistance of the first passivation layer 2 is less than the material resistance of the second passivation layer 3, so as to facilitate the realization of different resistances of the first passivation layer 2 and the second passivation layer 3; when the materials of the first passivation layer 2 and the second passivation layer 3 are the same, the resistance of the first passivation layer 2 can be achieved by changing the doping concentration of the first passivation layer 2 and the second passivation layer 3, the processing technology, etc. to achieve that the resistance of the first passivation layer 2 is less than the resistance of the second passivation layer 3.

[0097] As an embodiment of the present invention, it also includes:

[0098] A first back passivation layer 8, provided on a side of the P-type doped layer 4 away from the silicon substrate 1;

[0099] The second back passivation layer 9 is disposed on a side of the N-type doped layer 5 facing away from the silicon substrate 1 .

[0100] Among them, the first back passivation layer 8 and the second back passivation layer 9 may both include at least one or a combination of aluminum oxide film layers, silicon oxide film layers, silicon nitride film layers, silicon carbide film layers, and silicon oxynitride film layers. For example, in some embodiments, the first back passivation layer 8 and the second back passivation layer 9 may include aluminum oxide film layers and silicon nitride film layers stacked in sequence, and there is no specific limitation here.

[0101] In this embodiment, the first back passivation layer 8 and the second back passivation layer 9 can further enhance the battery passivation effect and improve the battery efficiency.

[0102] The embodiment of the present invention also provides a battery assembly, which includes the solar cell of the above embodiment. It should be noted that the battery assembly and the solar cell have the same or similar beneficial effects, and the relevant parts between the two can be referenced to each other. In order to avoid repetition, they will not be repeated here.

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

[0104] The solar cell provided by the embodiment of the present invention can improve the conductive effect of the first passivation layer 2 by setting the resistance of the first passivation layer 2 to be smaller than the resistance of the second passivation layer 3, and thereby improve the current transmission effect of the P region 11 by reducing the resistance of the first passivation layer 2, thereby achieving a balance between the current transmission effects of the P region 11 and the N region 12, and solving the problem of poor current transmission effect of the P region 11 of a traditional solar cell, so that both the P region 11 and the N region 12 of the solar cell can achieve good current transmission effects, thereby effectively improving the battery efficiency.

[0105] 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, It is characterized in that include: A silicon substrate, wherein a P region and an N region are provided on the surface of the silicon substrate; A first passivation layer, located in the P region and disposed on the surface of the silicon substrate; A second passivation layer, located in the N region and disposed on the surface of the silicon substrate; A P-type doped layer, disposed on a side of the first passivation layer away from the silicon substrate; An N-type doped layer, disposed on a side of the second passivation layer away from the silicon substrate; The resistance of the first passivation layer is smaller than the resistance of the second passivation layer.

2. The solar cell according to claim 1, It is characterized in that The first passivation layer contains a P-type dopant, and the second passivation layer contains an N-type dopant. The doping concentration of the P-type dopant in the first passivation layer is greater than the doping concentration of the N-type dopant in the second passivation layer.

3. The solar cell according to claim 2, It is characterized in that The doping concentration of the P-type dopant in the first passivation layer is 1×10 19 ~8×10 21 atoms / cm 3 The doping concentration of the N-type dopant in the second passivation layer is 5×10 18 ~5×10 21 atoms / cm 3 .

4. The solar cell according to claim 1, It is characterized in that The ratio of the resistance of the first passivation layer to the resistance of the second passivation layer is 0.2-1.

5. The solar cell according to claim 1, It is characterized in that The first passivation layer and the second passivation layer are both porous passivation layers, and the hole density of the first passivation layer is greater than the hole density of the second passivation layer.

6. The solar cell according to claim 1, It is characterized in that The first passivation layer and the second passivation layer are both porous passivation layers, and the average pore size of the holes in the first passivation layer is larger than the average pore size of the holes in the second passivation layer.

7. The solar cell according to claim 1, It is characterized in that The thickness of the first passivation layer is smaller than the thickness of the second passivation layer.

8. The solar cell according to claim 1, It is characterized in that A rate of change of the resistance of the first passivation layer with temperature change is greater than a rate of change of the resistance of the second passivation layer with temperature change.

9. The solar cell according to claim 1, It is characterized in that The resistance of the first passivation layer is 200Ω to 5000Ω; the resistance of the second passivation layer is 1000Ω to 25000Ω.

10. The solar cell according to claim 1, It is characterized in that The contact resistance of the first passivation layer is smaller than the contact resistance of the second passivation layer.

11. The solar cell according to claim 10, It is characterized in that The contact resistance of the first passivation layer is 0.2 to 5 mΩ·cm 2 .

12. The solar cell according to claim 10, It is characterized in that The contact resistance of the second passivation layer is 1 to 25 mΩ·cm 2 .

13. The solar cell according to claim 1, It is characterized in that The resistivity of the first passivation layer is lower than the resistivity of the second passivation layer.

14. The solar cell according to claim 13, It is characterized in that The resistivity of the first passivation layer is 500 Ω·cm to 10000 Ω·cm, and the resistivity of the second passivation layer is 2000 Ω·cm to 40000 Ω·cm.

15. The solar cell according to claim 1, It is characterized in that The resistance of the N-type doping layer is smaller than the resistance of the P-type doping layer.

16. The solar cell according to claim 1, It is characterized in that The bandgap width of the first passivation layer is smaller than the bandgap width of the second passivation layer.

17. The solar cell according to claim 1, It is characterized in that The bandgap width of the P-type doping layer is smaller than the bandgap width of the N-type doping layer.

18. The solar cell according to claim 1, It is characterized in that The dielectric constant of the first passivation layer is smaller than the dielectric constant of the second passivation layer.

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

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

21. A battery assembly, It is characterized in that A solar cell comprising any one of claims 1 to 20.

22. A photovoltaic system, It is characterized in that A battery assembly comprising the battery assembly described in claim 21 above.

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