Solar cell, cell assembly and photovoltaic system

Abstract

The invention is applicable to the field of photovoltaic technology, and provides a solar cell, a cell assembly and a photovoltaic system, the solar cell comprises a silicon wafer, the silicon wafer comprises a first area and a second area, and the first area is located on the back surface of the silicon wafer; the first doping layer is arranged in the first region; the second doping layer is arranged in the second region; the first passivation layer is arranged on the first doping layer; the second passivation layer is arranged on the second doping layer; the first electrode penetrates through the first passivation layer and is in contact with the first doping layer; the second electrode penetrates through the second passivation layer and is in contact with the second doping layer; the reflection insulation layer at least covers part of the area of the first passivation layer, the average reflectivity of the reflection insulation layer to light with the wavelength ranging from 800 nm to 1200 nm ranges from 50% to 95%, and the thickness of the reflection insulation layer is larger than that of the first passivation layer. According to the solar cell, the loss of long-wave-band sunlight escaping from the back can be reduced, and the conversion efficiency of the cell is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaic technology, and in particular to a solar cell, a cell module and a photovoltaic system. BACKGROUND

[0002] A solar cell is a kind of semiconductor device that converts solar energy into electrical energy. Under the condition of light, a photogenerated current is generated inside the solar cell, and the electrical energy is output through an electrode. In recent years, the production technology of solar cells has been continuously improved, the production cost has been continuously reduced, the conversion efficiency has been continuously improved, and the application of solar cell power generation has become increasingly widespread and has become an important energy source for power supply.

[0003] In the related art, because the silicon wafer of the solar cell has different absorption probabilities for different wavelengths of light, and the photon energy of the long-wave band is low, when the long-wave band light reaches the back of the solar cell, it cannot be completely absorbed by the silicon wafer, so that the sunlight is easy to escape from the back of the solar cell, resulting in low sunlight utilization rate, thereby leading to poor cell conversion efficiency. SUMMARY

[0004] The present application provides a solar cell, which aims to solve the problem of the prior art that the sunlight is easy to escape from the back of the solar cell, resulting in low sunlight utilization rate, thereby leading to poor cell conversion efficiency.

[0005] The present application is implemented in this way, and provides a solar cell, comprising:

[0006] A silicon wafer, the silicon wafer comprising a first region and a second region, the first region and the second region are both located on the back surface of the silicon wafer, or the first region is located on the back surface of the silicon wafer and the second region is located on the front surface of the silicon wafer;

[0007] A first doped layer provided on the first region;

[0008] A second doped layer provided on the second region;

[0009] A first passivation layer provided on the first doped layer;

[0010] A second passivation layer provided on the second doped layer;

[0011] A first electrode located in the first region, the first electrode penetrating through the first passivation layer and contacting the first doped layer;

[0012] A second electrode located in the second region, the second electrode penetrating through the second passivation layer and contacting the second doped layer; and

[0013] A reflective insulating layer is arranged on the back surface of the silicon wafer, the reflective insulating layer covers at least part of the first passivation layer, the average reflectivity of the reflective insulating layer to light with a wavelength ranging from 800 nm to 1200 nm is 50% to 95%, and the thickness of the reflective insulating layer is greater than the thickness of the first passivation layer.

[0014] Preferably, the first region and the second region are both located on the back surface of the silicon wafer, the first region and the second region are arranged alternately on the back surface of the silicon wafer, the reflective insulating layer covers at least part of the first passivation layer, and the reflective insulating layer covers at least part of the second passivation layer.

[0015] Preferably, the reflective insulating layer covers the first passivation layer and does not cover the first electrode, and the reflective insulating layer covers the second passivation layer and does not cover the second electrode.

[0016] Preferably, the back surface of the silicon wafer further comprises an isolation region arranged between the first region and the second region, and the solar cell further comprises a third passivation layer arranged on the isolation region, and the reflective insulating layer covers the third passivation layer.

[0017] Preferably, the thickness of the reflective insulating layer in the isolation region is greater than the thickness of the reflective insulating layer in the first region or the second region.

[0018] Preferably, the thickness of the reflective insulating layer in the isolation region is D1, and 6um < D1 < 71um, and the thickness of the reflective insulating layer in the first region or the second region is D2, and 5um < D2 < 70um.

[0019] Preferably, the reflective insulating layer covers part of the area of at least one of the first electrode and the second electrode.

[0020] Preferably, the reflective insulating layer covers part of the area or the entire area of the back surface which is not arranged with the first electrode and the second electrode.

[0021] Preferably, the first region is located on the back surface of the silicon wafer, the second region is located on the front surface of the silicon wafer, and the reflective insulating layer covers part of the area or the entire area of the first passivation layer.

[0022] Preferably, the reflective insulating layer covers part of the area of the first electrode.

[0023] Preferably, the reflective insulating layer covers part of the area or the entire area of the back surface which is not arranged with the first electrode.

[0024] Preferably, the thickness of the reflective insulating layer is greater than the height of the first electrode.

[0025] Preferably, the thickness of the reflective insulating layer is less than the height of the first electrode.

[0026] Preferably, the thickness of the reflective insulating layer is 10-100 microns, and the thickness of the first passivation layer is 100-200 nanometers.

[0027] Preferably, the thickness of the first passivation layer is 150-170 nanometers.

[0028] Preferably, the thickness of the reflective insulating layer is 35-45 microns.

[0029] Preferably, the area ratio of the reflective insulating layer to the back surface of the silicon wafer is 20%-95%.

[0030] The application provides a battery assembly comprising the above solar cell.

[0031] The application provides a photovoltaic system comprising the above battery assembly.

[0032] The solar cell provided by the application reflects at least part of the sunlight that has penetrated the silicon wafer back to the silicon wafer by arranging a reflective insulating layer on the back surface of the silicon wafer, increasing the optical path of the sunlight, thereby reducing the escape loss of the long-wave sunlight from the back surface of the solar cell and improving the conversion efficiency of the cell; moreover, the thickness of the reflective insulating layer is controlled to be greater than the thickness of the first passivation layer, so that the reflective insulating layer has a good reflectivity to light with a wavelength of 800-1200 nm, and the reflective insulating layer also has a good insulating effect, avoiding the occurrence of electric leakage. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 FIG. 1 is a sectional view of a solar cell according to an embodiment of the application;

[0034] Figure 2 FIG. 2 is another sectional view of a solar cell according to the embodiment of the application;

[0035] Figure 3 FIG. 3 is still another sectional view of a solar cell according to the embodiment of the application;

[0036] Figure 4 FIG. 4 is a sectional view of a solar cell according to another embodiment of the application. DETAILED DESCRIPTION

[0037] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. The examples of the embodiments are shown in the drawings, wherein identical or similar labels denote identical or similar elements or elements with identical or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0038] In the description of the present application, it should be understood that the terms "upper", "lower", "backlight surface", "front surface" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0039] In the present application, unless otherwise explicitly specified and limited, "on" or "under" of a first feature to a second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "above" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. The first feature "below", "below" and "below" of the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0040] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. In order to simplify the disclosure of the present application, the components and arrangements of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to the same reference numerals and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or arrangements discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.

[0041] Embodiment one

[0042] Please refer to Figures 1-3 The embodiment of the present application provides a solar cell, comprising:

[0043] The silicon wafer 1 comprises a first region 111 and a second region 112, and the first region 111 and the second region 112 are located on the back surface 11 of the silicon wafer 1.

[0044] a first doped layer 2 arranged in the first region 111;

[0045] a second doped layer 3 arranged in the second region 112;

[0046] a first passivation layer 4 arranged on the first doped layer 2;

[0047] a second passivation layer 5 arranged on the second doped layer 3;

[0048] a first electrode 6 located in the first region 111, the first electrode 6 penetrating the first passivation layer 4 and contacting the first doped layer 2;

[0049] a second electrode 7 located in the second region 112, the second electrode 7 penetrating the second passivation layer 5 and contacting the second doped layer 3; and

[0050] a reflective insulating layer 8 arranged on the back surface 11 of the silicon wafer 1, the reflective insulating layer 8 covering at least a part of the first passivation layer 4, the reflective insulating layer 8 having an average reflectivity of 50% to 95% for light having a wavelength in a range of 800 nm to 1200 nm, and the thickness D of the reflective insulating layer 8 being greater than the thickness d of the first passivation layer 4.

[0051] In the embodiment of the present application, the solar cell is a back contact solar cell, i.e., the electrodes of the solar cell are all arranged on the back surface 11 of the solar cell, i.e., the first electrode 6 and the second electrode 7 are both arranged on the back surface 11 of the solar cell, and the front surface 12 of the solar cell is not provided with an electrode. The back surface 11 of the silicon wafer 1 is specifically the back light surface of the solar cell, i.e., the surface of the solar cell facing away from sunlight when the solar cell is working, and the front surface 12 of the silicon wafer 1 is specifically the light-facing surface of the solar cell, i.e., the surface of the solar cell facing sunlight when the solar cell is working. The number of the first regions 111 and the second regions 112 is both multiple, and the multiple first regions 111 and the multiple second regions 112 are arranged alternately along a direction.

[0052] In the embodiment of the present application, the first doped layer 2 and the second doped layer 3 are one P-type doped layer and the other N-type doped layer. When the first doped layer 2 is a P-type doped layer, the first region 111 is a P-type doped region; when the second doped layer 3 is an N-type doped layer, the second region 112 is an N-type doped region. Alternatively, when the first doped layer 2 is an N-type doped layer, the first region 111 is an N-type doped region; when the second doped layer 3 is a P-type doped layer, the second region 112 is a P-type doped region. That is, one of the first region 111 and the second region 112 is a P-type doped region, and the other is an N-type doped region. The P-type doped layer is a doped layer doped with a P-type element, and the N-type doped layer is a doped layer doped with an N-type element, for example, the P-type element is boron element, and the N-type element is phosphorus element.

[0053] The thickness of the reflective insulating layer 8 is the interval distance between the opposite two side surfaces of the reflective insulating layer 8 along the thickness direction of the silicon wafer 1, and the thickness of the first passivation layer 4 is the interval distance between the opposite two side surfaces of the first passivation layer 4 along the thickness direction of the silicon wafer 1. The thickness of the reflective insulating layer 8 and the thickness of the first passivation layer 4 can be uniformly set or not uniformly set. The thickness of the reflective insulating layer 8 is greater than the thickness of the first passivation layer 4, which can be understood as that the average thickness of the reflective insulating layer 8 is greater than the average thickness of the first passivation layer 4; when the thickness of the reflective insulating layer 8 and the thickness of the first passivation layer 4 are uniformly set, the thickness of the reflective insulating layer 8 at any position is greater than the thickness of the first passivation layer 4 at any position; when the thickness of the reflective insulating layer 8 and the thickness of the first passivation layer 4 are not uniformly set, the minimum thickness of the reflective insulating layer 8 is greater than the maximum thickness of the first passivation layer 4, and the average thickness of the reflective insulating layer 8 can also be greater than the average thickness of the first passivation layer 4.

[0054] In the embodiment of the present application, the reflective insulating layer 8 covers at least part of the area of the first passivation layer 4, which can be understood as that the reflective insulating layer 8 can cover the entire area of the first passivation layer 4 or only part of the area of the first passivation layer 4. That is, the reflective insulating layer 8 covers at least part of the area of the first region 111 of the back surface 11 where the first electrode 6 is not arranged.

[0055] The solar cell provided by the embodiment of the present application is characterized in that the reflective insulating layer 8 is arranged on the back surface 11 of the silicon wafer 1, the average reflectivity of the reflective insulating layer 8 to light with a wavelength of 800nm-1200nm is 50%-95%, the reflective insulating layer 8 covers at least part of the area of the first passivation layer 4, at least part of the sunlight emitted from the back surface 11 of the silicon wafer 1 is reflected back to the silicon wafer 1, the optical path of the sunlight is increased, the escape loss of the sunlight with a long wavelength (800nm-1200nm) from the back surface 11 of the solar cell is reduced, and the conversion efficiency of the cell is improved; and the thickness D of the reflective insulating layer 8 is greater than the thickness d of the first passivation layer 4, which can realize good reflectivity of the reflective insulating layer 8 to light with a wavelength of 800nm-1200nm and also ensure good insulation effect of the reflective insulating layer 8 and avoid the occurrence of electric leakage.

[0056] In the embodiment of the present application, the first passivation layer 4 plays a passivation role on the surface of the first doped layer 2, and the second passivation layer 5 plays a passivation role on the surface of the second doped layer 3, which is beneficial to improving the cell efficiency.

[0057] As an embodiment of the present application, the reflective insulating layer 8 comprises organic resin and titanium white powder, and the weight of the titanium white powder in the reflective insulating layer 8 accounts for 20% to 60% of the total weight of the reflective insulating layer 8. The organic resin can be epoxy resin in particular, and the titanium white powder can be titanium dioxide in particular. Controlling the weight of the titanium white powder in the reflective insulating layer 8 to account for 20% to 60% of the total weight of the reflective insulating layer 8 makes the reflective insulating layer 8 white and satisfies the average reflectivity of the reflective insulating layer 8 to light with a wavelength ranging from 800 nm to 1200 nm being 50% to 95%. For example, the average reflectivity of the reflective insulating layer 8 to light with a wavelength ranging from 800 nm to 1200 nm can be any value among 50%, 52%, 55%, 60%, 65%, 70%, 76%, 80%, 87%, 90%, 93%, and 95%.

[0058] As an embodiment of the present application, the first region 111 and the second region 112 are both located on the back surface 11 of the silicon wafer 1, the first region 111 and the second region 112 are alternately arranged on the back surface 11 of the silicon wafer 1, the reflective insulating layer 8 covers at least part of the first passivation layer 4, and the reflective insulating layer 8 covers at least part of the second passivation layer 5.

[0059] In the embodiment of the present application, the reflective insulating layer 8 can cover the first region 111 or the second region 112. Specifically, the reflective insulating layer 8 can cover part of the first passivation layer 4 or the whole of the first passivation layer 4, and the reflective insulating layer 8 can cover part of the second passivation layer 5 or the whole of the second passivation layer 5. Since the reflective insulating layer 8 covers at least part of the first passivation layer 4 and at least part of the second passivation layer 5, the first region 111 and the second region 112 can both reflect the sunlight escaping from the first region 111 and the second region 112 through the reflective insulating layer 8, further reducing the escape loss of long-wavelength light on the back surface 11 and improving the conversion efficiency of the battery.

[0060] As an embodiment of the present application, the reflective insulating layer 8 covers the first passivation layer 4 and does not cover the first electrode 6, and the reflective insulating layer 8 covers the second passivation layer 5 and does not cover the second electrode 7.

[0061] In the embodiment, the reflective insulating layer 8 covers the first passivation layer 4 and does not cover the first electrode 6, and the reflective insulating layer 8 covers the second passivation layer 5 and does not cover the second electrode 7, which facilitates the welding of the electrodes.

[0062] As another embodiment of the present application, the reflective insulating layer 8 covers part of at least one of the first electrode 6 and the second electrode 7.

[0063] The reflective insulating layer 8 can also cover part of the first electrode 6 and the second electrode 7. The reflective insulating layer 8 can cover the first passivation layer 4 and part of the first electrode 6, and the reflective insulating layer 8 can cover the second passivation layer 5 and part of the second electrode 7. The reflective insulating layer 8 can protect the first electrode 6 and the second electrode 7, and can improve the corrosion resistance of the first electrode 6 and the second electrode 7. The first electrode 6 and the second electrode 7 can be main grids of the solar cell, or can be fine grids of the solar cell. The specific electrode type is determined according to the grid line arrangement on the solar cell.

[0064] As an embodiment of the present application, the back surface 11 of the silicon wafer 1 further comprises an isolation area 113 located between the first area 111 and the second area 112, and the solar cell further comprises a third passivation layer 9 located on the isolation area 113, and the reflective insulating layer 8 covers the third passivation layer 9.

[0065] In this embodiment, the isolation area 113 can be a groove. The isolation area 113 can physically isolate the first doped layer 2 and the second doped layer 3, and improve the insulation effect between the first doped layer 2 and the second doped layer 3. By arranging the third passivation layer 9 on the isolation area 113, and the reflective insulating layer 8 covering the third passivation layer 9, the third passivation layer 9 passivates the isolation area 113, and the reflective insulating layer 8 at the position of the isolation area 113 reflects the sunlight transmitted from the isolation area 113 back into the silicon wafer 1, which can further reduce the escape loss of the sunlight on the back surface 11, and further improve the conversion efficiency of the solar cell.

[0066] The first passivation layer 4, the second passivation layer 5, and the third passivation layer 9 are integrally formed, and are deposited at one time. The thickness and the material of the first passivation layer 4, the second passivation layer 5, and the third passivation layer 9 can be the same or different. Preferably, the thickness and the material of the first passivation layer 4, the second passivation layer 5, and the third passivation layer 9 are the same, which facilitates the deposition of the first passivation layer 4, the second passivation layer 5, and the third passivation layer 9 at one time. Optionally, the first passivation layer 4, the second passivation layer 5, and the third passivation layer 9 are one of a silicon nitride layer, a silicon oxynitride layer, a silicon oxide layer, or a stack of at least two of them.

[0067] As an embodiment of the present application, the thickness D1 of the reflective insulating layer 8 located in the isolation area 113 is greater than the thickness D2 of the reflective insulating layer 8 located in the first area 111 or the second area 112.

[0068] In the embodiment, since the isolation region 113 is not provided with a doped layer and is generally provided with a rough surface, the sunlight is transmitted more and reflected less from the isolation region 113, and the sunlight in a long wave band is more likely to escape from the isolation region 113, and thus the thickness D1 of the reflective insulating layer 8 located at the isolation region 113 is greater than the thickness D2 of the reflective insulating layer 8 located at the first region 111 or the second region 112, that is, the thickness of the reflective insulating layer 8 at the isolation region 113 is designed to be thickened, which is beneficial to further improve the reflection effect of the reflective insulating layer 8 on the transmitted light of the isolation region 113, further reduce the escape loss of the sunlight from the back surface 11, and further improve the conversion efficiency of the battery. Of course, in some other embodiments, the thickness of the reflective insulating layer 8 located at the isolation region 113 can also be equal to or less than the thickness of the reflective insulating layer 8 located at the first region 111 or the second region 112.

[0069] As an embodiment of the present application, the thickness of the reflective insulating layer 8 located at the isolation region 113 is D1, and 6um < D1 < 71um; the thickness of the reflective insulating layer 8 at the first region 111 or the second region 112 is D2, and 5um < D2 < 70um.

[0070] In the embodiment, 6um < D1 < 71um and 5um < D2 < 70um are controlled, so that the thickness range of the reflective insulating layer 8 located at the isolation region 113 and the thickness range of the reflective insulating layer 8 located at the first region 111 or the second region 112 are more reasonable, which can improve the reflection effect of the reflective insulating layer 8 on the transmitted light of the isolation region 113, reduce the escape loss of the sunlight from the back surface 11, improve the conversion efficiency of the battery, and also facilitate the printing preparation of the reflective insulating layer 8.

[0071] As shown in FIG. 1, Figure 1 As an embodiment of the present application, the reflective insulating layer 8 covers the entire region of the back surface 11 which is not provided with the first electrode 6 and the second electrode 7.

[0072] In the embodiment, the reflective insulating layer 8 covers the entire region of the back surface 11 which is not provided with the first electrode 6 and the second electrode 7, that is, the reflective insulating layer 8 is provided in the regions of the back surface 11 except the regions provided with the first electrode 6 and the second electrode 7, and at this time, the reflective insulating layer 8 completely covers the first region 111, the second region 112 and the isolation region 113 of the back surface 11, and the reflective insulating layer 8 does not cover the first electrode 6 and the second electrode 7. Since the reflective insulating layer 8 covers the entire region of the back surface 11 which is not provided with the first electrode 6 and the second electrode 7, the transmitted light from the regions of the back surface 11 which are not provided with the first electrode 6 and the second electrode 7 can be reflected back into the silicon wafer 1 by the reflective insulating layer 8 again, which can greatly reduce the escape loss of the sunlight from the back surface 11 and further improve the conversion efficiency of the battery.

[0073] As shown in FIG. 1, Figure 2As shown, as one embodiment of the present application, the reflective insulating layer 8 covers the part of the back surface 11 where the first electrode 6 and the second electrode 7 are not arranged.

[0074] In this embodiment, the reflective insulating layer 8 covers the part of the back surface 11 where the first electrode 6 and the second electrode 7 are not arranged, that is, the reflective insulating layer 8 does not completely cover the area of the back surface 11 except the first electrode 6 and the second electrode 7, for example, a blank area can be left between the electrode and the reflective insulating layer 8 which is not covered by the reflective insulating layer 8; or alternatively, the reflective insulating layer 8 only covers part of the first area 111, the second area 112 or the isolation area 113. Since the reflective insulating layer 8 covers the part of the back surface 11 where the first electrode 6 and the second electrode 7 are not arranged, part of the back surface 11 is not covered by the reflective insulating layer 8, which can improve the bifaciality of the solar cell and facilitate the application of the solar cell in the scene of double-sided light receiving.

[0075] As one embodiment of the present application, the thickness D of the reflective insulating layer 8 is greater than the height H of the first electrode 6.

[0076] In this embodiment, the thickness D of the reflective insulating layer 8 is greater than the height H of the first electrode 6, which can be understood as controlling the thickness D of the reflective insulating layer 8 to be greater than the height of the first electrode 6, so that compared with the first electrode 6, the thickness D of the reflective insulating layer 8 is increased in design, which can improve the reflection effect of the reflective insulating layer 8 on sunlight, further reduce the escape loss of sunlight from the back surface 11, and improve the conversion efficiency of the cell. The height H of the first electrode 6 and the height of the second electrode 7 can be the same or different. Alternatively, the thickness D of the reflective insulating layer 8 is greater than the height H of the first electrode 6 and the height of the second electrode 7.

[0077] As another embodiment of the present application, the thickness D of the reflective insulating layer 8 is less than the height H of the first electrode 6.

[0078] In this embodiment, the thickness D of the reflective insulating layer 8 is less than the height H of the first electrode 6, which can be understood as reducing the thickness D of the reflective insulating layer 8 in design, so that the thickness D of the reflective insulating layer 8 is less than the height of the first electrode 6. Since the thickness D of the reflective insulating layer 8 is too large, the reflective insulating layer 8 may be warped during curing, and the smaller the thickness D of the reflective insulating layer 8, the smaller the warping degree of the cell. Therefore, controlling the thickness D of the reflective insulating layer 8 to be less than the height of the first electrode 6 is beneficial to reduce the warping degree of the cell. Alternatively, the thickness D of the reflective insulating layer 8 is less than the height H of the first electrode 6 and the height of the second electrode 7.

[0079] As one embodiment of the present application, the thickness D of the reflective insulating layer 8 is 10-100 microns, and the thickness d of the first passivation layer 4 is 100-200 nanometers.

[0080] In the embodiment, the thickness D of the reflective insulating layer 8 is 10-100 microns. It can be understood that the thickness of the reflective insulating layer 8 at any position is within the range of 10-100 microns. The thickness d of the first passivation layer 4 is 100-200 nanometers. It can be understood that the thickness of the first passivation layer 4 at any position is within the range of 100-200 nanometers. By controlling the thickness D of the reflective insulating layer 8 to be 10-100 microns and the thickness d of the first passivation layer 4 to be 100-200 nanometers, the reflective insulating layer 8 can have good reflectivity to light with a wavelength of 800-1200 nm, and the first passivation layer 4 can have good passivation effect.

[0081] For example, the thickness D of the reflective insulating layer 8 can be any value within the range of 10 microns, 15 microns, 18 microns, 20 microns, 22 microns, 28 microns, 30 microns, 33 microns, 37 microns, 40 microns, 42 microns, 46 microns, 50 microns, 55 microns, 60 microns, 65 microns, 70 microns, 72 microns, 78 microns, 80 microns, 81 microns, 84 microns, 88 microns, 90 microns, 92 microns, 96 microns, and 100 microns.

[0082] For example, the thickness d of the first passivation layer 4 can be any value within the range of 100 nanometers, 105 nanometers, 108 nanometers, 110 nanometers, 115 nanometers, 120 nanometers, 125 nanometers, 130 nanometers, 132 nanometers, 138 nanometers, 140 nanometers, 145 nanometers, 150 nanometers, 155 nanometers, 160 nanometers, 165 nanometers, 170 nanometers, 172 nanometers, 178 nanometers, 180 nanometers, 185 nanometers, 188 nanometers, 190 nanometers, 193 nanometers, 195 nanometers, and 200 nanometers.

[0083] As an embodiment of the present application, the thickness D of the reflective insulating layer 8 is 35-45 microns.

[0084] In the embodiment, the thickness D of the reflective insulating layer 8 is further controlled to be 35-45 microns, thereby further ensuring the good reflectivity of the reflective insulating layer 8 to light with a wavelength of 800-1200 nm.

[0085] As an embodiment of the present application, the thickness d of the first passivation layer 4 is 150-170 nanometers.

[0086] In the embodiment, the thickness d of the first passivation layer 4 is further controlled to be 150-170 nanometers, thereby further ensuring the good passivation effect of the first passivation layer 4.

[0087] As an embodiment of the present application, the area ratio of the reflective insulating layer 8 to the back surface 11 of the silicon wafer 1 is 20%-95%.

[0088] In the embodiment, the area ratio of the reflective insulating layer 8 to the back surface 11 of the silicon wafer 1 is 20% to 95%, which can be understood as the area ratio of the sum of the areas of all the reflective insulating layers 8 to the total area of the back surface 11 of the silicon wafer 1 is 20% to 95%. The area ratio of the reflective insulating layer 8 to the back surface 11 of the silicon wafer 1 is controlled to be 20% to 95%, so that the area ratio of the reflective insulating layer 8 on the back surface 11 of the silicon wafer 1 is appropriate, the reflective insulating layer 8 can better reflect the sunlight penetrating through the silicon wafer 1 back to the silicon wafer 1, and the reflective insulating layer 8 can avoid completely covering the first electrode 6 or the second electrode 7, thereby facilitating the welding of the first electrode 6 or the second electrode 7 and the solder strip. For example, the area ratio of the reflective insulating layer 8 to the back surface 11 of the silicon wafer 1 can be 40% to 50%; or the area ratio of the reflective insulating layer 8 to the back surface 11 of the silicon wafer 1 is 30% to 40%.

[0089] Embodiment two

[0090] Please refer to Figure 4 , the embodiment of the present application provides a solar cell, comprising:

[0091] The silicon wafer 1 comprises a first region 111 and a second region 112, the first region 111 is located on the back surface 11 of the silicon wafer 1, and the second region 112 is located on the front surface 12 of the silicon wafer 1.

[0092] The first doped layer 2 is arranged on the first region 111;

[0093] The second doped layer 3 is arranged on the second region 112;

[0094] The first passivation layer 4 is arranged on the first doped layer 2;

[0095] The second passivation layer 5 is arranged on the second doped layer 3;

[0096] The first electrode 6 is located in the first region 111, and the first electrode 6 penetrates through the first passivation layer 4 and contacts the first doped layer 2;

[0097] The second electrode 7 is located in the second region 112, and the second electrode 7 penetrates through the second passivation layer 5 and contacts the second doped layer 3; and

[0098] The reflective insulating layer 8 is arranged on the back surface 11 of the silicon wafer 1, the reflective insulating layer 8 covers part or all of the first passivation layer 4, the average reflectivity of the reflective insulating layer 8 to light with a wavelength of 800 nm to 1200 nm is 50% to 95%, and the thickness D of the reflective insulating layer 8 is greater than the thickness d of the first passivation layer 4.

[0099] The embodiment is different from the embodiment one in that the solar cell is a double-sided contact solar cell, that is, the positive electrode and the negative electrode of the solar cell are arranged on the front surface 12 and the back surface 11 of the solar cell respectively, that is, the first electrode 6 is arranged on the back surface 11 of the solar cell, and the second electrode 7 is arranged on the front surface 12 of the solar cell. The back surface 11 of the silicon wafer 1 is specifically the back light surface of the solar cell, that is, the surface of the solar cell facing away from sunlight during operation, and the front surface 12 of the silicon wafer 1 is specifically the light-facing surface of the solar cell, that is, the surface of the solar cell facing sunlight during operation. The first region 111, the first doped layer 2 and the first passivation layer 4 are arranged on the back surface 11 of the solar cell, and the second region 112, the second doped layer 3 and the second passivation layer 5 are arranged on the front surface 12 of the solar cell. In this embodiment, the entire back surface 11 of the solar cell can be the first region 111, or only a partial region of the back surface 11 is the first region 111; and the entire front surface 12 of the solar cell can be the second region 112, or only a partial region of the front surface 12 is the second region 112.

[0100] In the embodiment, the first doped layer 2 and the second doped layer 3 are one P-type doped layer and the other N-type doped layer. When the first doped layer 2 is a P-type doped layer, the first region 111 is a P-type doped region; and when the second doped layer 3 is an N-type doped layer, the second region 112 is an N-type doped region. Alternatively, when the first doped layer 2 is an N-type doped layer, the first region 111 is an N-type doped region; and when the second doped layer 3 is a P-type doped layer, the second region 112 is a P-type doped region. That is, one of the first region 111 and the second region 112 is a P-type doped region, and the other is an N-type doped region. The P-type doped layer is a doped layer doped with a P-type element, and the N-type doped layer is a doped layer doped with an N-type element, for example, the P-type element is boron element, and the N-type element is phosphorus element.

[0101] The thickness D of the reflective insulating layer 8 and the thickness d of the first passivation layer 4 can be uniformly arranged or not uniformly arranged. The thickness D of the reflective insulating layer 8 is greater than the thickness d of the first passivation layer 4, which can be understood as that the average thickness of the reflective insulating layer 8 is greater than the average thickness of the first passivation layer 4; when the thickness D of the reflective insulating layer 8 and the thickness d of the first passivation layer 4 are uniformly arranged, the thickness of the reflective insulating layer 8 at any position is greater than the thickness of the first passivation layer 4 at any position; when the thickness D of the reflective insulating layer 8 and the thickness d of the first passivation layer 4 are not uniformly arranged, the minimum thickness of the reflective insulating layer 8 is greater than the maximum thickness of the first passivation layer 4, and the average thickness of the reflective insulating layer 8 is also greater than the average thickness of the first passivation layer 4.

[0102] In the embodiment of the present application, the reflective insulating layer 8 can cover the whole area of the first passivation layer 4, or can only cover part of the area of the first passivation layer 4. That is, the reflective insulating layer 8 covers at least part of the area of the first passivation layer 4 where the first electrode 6 is not arranged.

[0103] In the embodiment of the present application, the reflective insulating layer 8 is arranged on the back surface 11 of the silicon wafer 1, the average reflectivity of the reflective insulating layer 8 to light with a wavelength in the range of 800nm-1200nm is 50%-95%, the reflective insulating layer 8 covers at least part of the area of the first passivation layer 4, the reflective insulating layer 8 can reflect at least part of the sunlight escaping from the back surface 11 back to the silicon wafer 1, increase the optical path of the sunlight, thereby reducing the escape loss of the sunlight with a long wavelength from the back surface 11, and improving the conversion efficiency of the solar cell; and the thickness D of the reflective insulating layer 8 is greater than the thickness d of the first passivation layer 4, which can achieve good reflectivity of the reflective insulating layer 8 to light with a wavelength in the range of 800nm-1200nm, and also ensures good insulation effect of the reflective insulating layer 8, avoiding the risk of electric leakage.

[0104] As an embodiment of the present application, the reflective insulating layer 8 comprises an organic resin material and titanium white powder, and the weight of the titanium white powder in the reflective insulating layer 8 accounts for 20%-60% of the total weight of the reflective insulating layer 8. The organic resin material can be epoxy resin, and the titanium white powder can be titanium dioxide. Controlling the weight of the titanium white powder in the reflective insulating layer 8 to account for 20%-60% of the total weight of the reflective insulating layer 8 can make the reflective insulating layer 8 white, and meet the requirement that the average reflectivity of the reflective insulating layer 8 to light with a wavelength in the range of 800nm-1200nm is 50%-95%.

[0105] As an embodiment of the present application, the first area 111 is located on the back surface 11 of the silicon wafer 1, the second area 112 is located on the front surface 12 of the silicon wafer 1, and the reflective insulating layer 8 covers part of the area of the first passivation layer 4 where the first electrode 6 is not arranged or covers the whole area of the first passivation layer 4.

[0106] In the embodiment, the reflective insulating layer 8 covers the first passivation layer 4 and does not cover the first electrode 6, which is convenient for welding of the first electrode 6.

[0107] As another embodiment of the present application, the reflective insulating layer 8 covers part of the area of the first electrode 6.

[0108] In the embodiment, the reflective insulating layer 8 covers the first passivation layer 4 and covers part of the area of the first electrode 6. The reflective insulating layer 8 can also cover part of the area of the first electrode 6, and the reflective insulating layer 8 can play a certain protective role on the first electrode 6, which can improve the corrosion resistance of the first electrode 6.

[0109] As an embodiment of the present application, the reflective insulating layer 8 covers the entire area of the back surface 11 where the first electrode 6 is not arranged.

[0110] In this embodiment, the reflective insulating layer 8 covers the entire area of the back surface 11 where the first electrode 6 is not arranged, that is, the reflective insulating layer 8 is arranged on the area of the back surface 11 except the first electrode 6. Since the reflective insulating layer 8 covers the entire area of the back surface 11 where the first electrode 6 is not arranged, the transmitted light from the area of the back surface 11 where the first electrode 6 is not arranged can be reflected back into the silicon wafer 1 again by the reflective insulating layer 8, which can greatly reduce the escape loss of the sunlight from the back surface 11 and further improve the conversion efficiency of the battery.

[0111] As an embodiment of the present application, the reflective insulating layer 8 covers part of the area of the back surface 11 where the first electrode 6 is not arranged.

[0112] In this embodiment, the reflective insulating layer 8 covers part of the area of the back surface 11 where the first electrode 6 is not arranged, that is, the reflective insulating layer 8 does not completely cover the area of the back surface 11 where the first electrode 6 is not arranged, for example, a blank area can be left between the first electrode 6 and the reflective insulating layer 8 which is not covered by the reflective insulating layer 8. Since the reflective insulating layer 8 covers part of the area of the back surface 11 where the first electrode 6 is not arranged, part of the area of the back surface 11 is not covered by the reflective insulating layer 8, which can improve the double-sided rate of the solar cell and facilitate the application of the solar cell in the scenario of double-sided light receiving.

[0113] As an embodiment of the present application, the thickness D of the reflective insulating layer 8 is greater than the height H of the first electrode 6.

[0114] In this embodiment, the thickness D of the reflective insulating layer 8 is greater than the height H of the first electrode 6, which can be understood as controlling the thickness D of the reflective insulating layer 8 to be greater than the height of the first electrode 6, so that the thickness D of the reflective insulating layer 8 is increased compared with the first electrode 6, which can improve the reflection effect of the reflective insulating layer 8 on the sunlight, facilitate further reducing the escape loss of the sunlight from the back surface 11, and improve the conversion efficiency of the battery.

[0115] As another embodiment of the present application, the thickness D of the reflective insulating layer 8 is less than the height H of the first electrode 6.

[0116] In this embodiment, the thickness D of the reflective insulating layer 8 is less than the height H of the first electrode 6, which can be understood as reducing the thickness D of the reflective insulating layer 8 to be less than the height of the first electrode 6. Since the thickness D of the reflective insulating layer 8 is too large, the battery may be warped during the curing process of the reflective insulating layer 8, and the smaller the thickness D of the reflective insulating layer 8 is, the smaller the warping degree of the battery wafer can be. Therefore, controlling the thickness D of the reflective insulating layer 8 to be less than the height of the first electrode 6 is beneficial to reducing the warping degree of the battery wafer.

[0117] As an embodiment of the present application, the thickness D of the reflective insulating layer 8 is 10-100 microns, and the thickness d of the first passivation layer 4 is 100-200 nanometers.

[0118] In the embodiment, the thickness D of the reflective insulating layer 8 is 10-100 microns, and it can be understood that the thickness of the reflective insulating layer 8 at any position is within the range of 10-100 microns. The thickness d of the first passivation layer 4 is 100-200 nanometers, and it can be understood that the thickness of the first passivation layer 4 at any position is within the range of 100-200 nanometers. By controlling the thickness D of the reflective insulating layer 8 to be 10-100 microns and the thickness d of the first passivation layer 4 to be 100-200 nanometers, the good reflectivity of the reflective insulating layer 8 to light with a wavelength in the range of 800 nm-1200 nm can be ensured, and the good passivation effect of the first passivation layer 4 can be ensured.

[0119] For example, the thickness D of the reflective insulating layer 8 can be any value in the range of 10 microns, 15 microns, 18 microns, 20 microns, 22 microns, 28 microns, 30 microns, 33 microns, 37 microns, 40 microns, 42 microns, 46 microns, 50 microns, 55 microns, 60 microns, 65 microns, 70 microns, 72 microns, 78 microns, 80 microns, 81 microns, 84 microns, 88 microns, 90 microns, 92 microns, 96 microns, 100 microns.

[0120] For example, the thickness d of the first passivation layer 4 can be any value in the range of 100 nanometers, 105 nanometers, 108 nanometers, 110 nanometers, 115 nanometers, 120 nanometers, 125 nanometers, 130 nanometers, 132 nanometers, 138 nanometers, 140 nanometers, 145 nanometers, 150 nanometers, 155 nanometers, 160 nanometers, 165 nanometers, 170 nanometers, 172 nanometers, 178 nanometers, 180 nanometers, 185 nanometers, 188 nanometers, 190 nanometers, 193 nanometers, 195 nanometers, 200 nanometers.

[0121] As an embodiment of the present application, the thickness D of the reflective insulating layer 8 is 35-45 microns.

[0122] In the embodiment, the thickness D of the reflective insulating layer 8 is further controlled to be 35-45 microns, and the good reflectivity of the reflective insulating layer 8 to light with a wavelength in the range of 800 nm-1200 nm is further ensured.

[0123] As an embodiment of the present application, the thickness d of the first passivation layer 4 is 150-170 nanometers.

[0124] In the embodiment, the thickness d of the first passivation layer 4 is further controlled to be 150-170 nanometers, and the good passivation effect of the first passivation layer 4 is further ensured.

[0125] As an embodiment of the present application, the ratio of the area of the reflective insulation layer 8 to the area of the back surface 11 of the silicon wafer 1 is 20% to 95%.

[0126] In this embodiment, the ratio of the area of the reflective insulation layer 8 to the area of the back surface 11 of the silicon wafer 1 is 20% to 95%. It can be understood that the ratio of the sum of the areas of all the reflective insulation layers 8 to the total area of the back surface 11 of the silicon wafer 1 is 20% to 95%. Controlling the ratio of the area of the reflective insulation layer 8 to the area of the back surface 11 of the silicon wafer 1 to be 20% to 95% makes the area of the reflective insulation layer 8 on the back surface 11 of the silicon wafer 1 appropriate, and the reflective insulation layer 8 can better reflect the sunlight that has passed through the silicon wafer 1 back to the silicon wafer 1, and avoids the reflective insulation layer 8 completely covering the first electrode 6 or the second electrode 7, facilitating the welding of the first electrode 6 or the second electrode 7 and the solder strip. For example, the ratio of the area of the reflective insulation layer 8 to the area of the back surface 11 of the silicon wafer 1 can be 40% to 50%; or alternatively, the ratio of the area of the reflective insulation layer 8 to the area of the back surface 11 of the silicon wafer 1 is 30% to 40%.

[0127] Embodiment three

[0128] The present application also provides a battery assembly comprising the solar cell of the above-mentioned embodiments. It should be noted that the battery assembly has the same or similar beneficial effects as the above-mentioned solar cell, and the relevant parts between the two can be mutually referred to, in order to avoid repetition, which will not be described here.

[0129] In this embodiment, the plurality of solar cells in the battery assembly can be sequentially connected in series to form a cell string, thereby realizing the series connection of the current output. For example, the connection of the cell pieces can be realized by setting a solder strip (bus bar, interconnection strip), a conductive back plate, etc.

[0130] It can be understood that in such embodiments, the battery assembly can also include a metal frame, a back plate, photovoltaic glass, and a film. The film can be filled between the front and back surfaces of the solar cell, photovoltaic glass, adjacent cell pieces, etc., as a filler, which can be a transparent gel with good light transmission performance and aging resistance, for example, the film can use EVA film or POE film, which can be selected according to actual conditions, and is not limited here.

[0131] The photovoltaic glass can be covered on the film on the front surface of the solar cell. The photovoltaic glass can be super white glass, which has high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, the light transmittance of super white glass can be more than 92%, which can protect the solar cell as much as possible without affecting the efficiency of the solar cell. At the same time, the film can bond the photovoltaic glass and the solar cell together, and the presence of the film can seal and insulate the solar cell and prevent water and moisture.

[0132] The back plate can be attached to the adhesive film on the back of the solar cell. The back plate can protect and support the solar cell, has reliable insulation, water resistance and aging resistance, and can have multiple options, such as tempered glass, organic glass, aluminum alloy TPT composite adhesive film, etc. The specific setting can be made according to the specific situation, which is not limited here. The whole composed of the back plate, the solar cell, the adhesive film and the photovoltaic glass can be arranged on the metal frame. The metal frame serves as the main external support structure of the entire solar cell module, and can stably support and install the solar cell module. For example, the solar cell module can be installed at the desired installation position through the metal frame.

[0133] Embodiment four

[0134] The embodiment of the present application also provides a photovoltaic system comprising the solar cell module of the above-mentioned embodiment. It should be noted that the photovoltaic system has the same or similar beneficial effects as the above-mentioned solar cell, and the relevant parts between the two can be referred to each other. In order to avoid repetition, it will not be described here.

[0135] In the present embodiment, the photovoltaic system can be applied in a photovoltaic power station, such as a ground power station, a roof power station, a water surface power station, etc., and can also be applied in a device or apparatus using solar energy to generate electricity, such as a user solar power source, a solar street lamp, a solar car, a solar building, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be applied in all fields requiring solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system can include a photovoltaic array, a combiner box and an inverter. The photovoltaic array can be an array combination of a plurality of solar cell modules. For example, a plurality of solar cell modules can form a plurality of photovoltaic arrays. The photovoltaic array is connected to the combiner box. The combiner box can combine the current generated by the photovoltaic array. The combined current flows through the inverter to convert into alternating current required by the power grid, and then is connected to the power grid to realize solar power supply.

[0136] In the description of the present specification, the description of the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0137] The above merely preferred embodiments of the present application are not used to limit the present application, any modification, equivalent replacement and improvement etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A solar cell, characterized in that, include: A silicon wafer, the silicon wafer including a first region and a second region, the first region and the second region being located on the back side of the silicon wafer, or the first region being located on the back side of the silicon wafer and the second region being located on the front side of the silicon wafer; A first doped layer is disposed in the first region; A second doped layer is disposed in the second region; A first passivation layer is disposed on the first doped layer; A second passivation layer is disposed on the second doped layer; A first electrode located in the first region, the first electrode passing through the first passivation layer and contacting the first doped layer; A second electrode located in the second region, the second electrode passing through the second passivation layer and contacting the second doped layer; and A reflective insulating layer is disposed on the back side of the silicon wafer, the reflective insulating layer at least covers a portion of the first passivation layer, the reflective insulating layer has an average reflectivity of 50% to 95% for light in the wavelength range of 800nm ​​to 1200nm, and the thickness of the reflective insulating layer is greater than the thickness of the first passivation layer.

2. The solar cell according to claim 1, characterized in that, Both the first region and the second region are located on the back side of the silicon wafer, and the first region and the second region are alternately disposed on the back side of the silicon wafer. The reflective insulating layer covers at least a portion of the first passivation layer, and the reflective insulating layer covers at least a portion of the second passivation layer.

3. The solar cell according to claim 2, characterized in that, The reflective insulating layer covers the first passivation layer but does not cover the first electrode, and the reflective insulating layer covers the second passivation layer but does not cover the second electrode.

4. The solar cell according to claim 2 or 3, characterized in that, The back side of the silicon wafer also includes an isolation region disposed between the first region and the second region, and the solar cell also includes a third passivation layer disposed on the isolation region, and the reflective insulating layer covers the third passivation layer.

5. The solar cell according to claim 4, characterized in that, The thickness of the reflective insulating layer in the isolation zone is greater than the thickness of the reflective insulating layer in the first region or the second region.

6. The solar cell according to claim 5, characterized in that, The thickness of the reflective insulating layer in the isolation zone is D1, 6um < D1 < 71um; the thickness of the reflective insulating layer in the first region or the second region is D2, 5um < D2 < 70um.

7. The solar cell according to claim 2, characterized in that, The reflective insulating layer covers a portion of at least one of the first electrode and the second electrode.

8. The solar cell according to claim 2, characterized in that, The reflective insulating layer covers part or all of the area on the back side where the first and second electrodes are not located.

9. The solar cell according to claim 1, characterized in that, The first region is located on the back side of the silicon wafer, the second region is located on the front side of the silicon wafer, and the reflective insulating layer covers part or all of the first passivation layer.

10. The solar cell according to claim 9, characterized in that, The reflective insulating layer covers a portion of the first electrode.

11. The solar cell according to claim 9, characterized in that, The reflective insulating layer covers part or all of the area on the back side that is not where the first electrode is located.

12. The solar cell according to claim 2 or 9, characterized in that, The thickness of the reflective insulating layer is greater than the height of the first electrode.

13. The solar cell according to claim 2 or 9, characterized in that, The thickness of the reflective insulating layer is less than the height of the first electrode.

14. The solar cell according to claim 1, characterized in that, The thickness of the reflective insulating layer is 10 to 100 micrometers, and the thickness of the first passivation layer is 100 to 200 nanometers.

15. The solar cell according to claim 14, characterized in that, The thickness of the first passivation layer is 150–170 nanometers.

16. The solar cell according to claim 1, characterized in that, The thickness of the reflective insulating layer is 35–45 micrometers.

17. The solar cell according to claim 1, characterized in that, The ratio of the area of ​​the reflective insulating layer to the area of ​​the back side of the silicon wafer is 20% to 95%.

18. A battery assembly, characterized in that, Including the solar cell as described in any one of claims 1 to 17.

19. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 18.

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