Back contact battery, battery assembly and photovoltaic system

Abstract

The utility model relates to the technical field of solar cells, and particularly discloses a back contact cell, a cell assembly and a photovoltaic system, the back contact cell comprises a silicon substrate, the silicon substrate is provided with a light receiving surface and a backlight surface which are oppositely arranged; a doping layer and an electrode layer are sequentially arranged on the backlight face in the direction away from the light receiving face. The doped layer comprises N-type doped regions and P-type doped regions which are alternately arranged at intervals; the electrode layer comprises an N-type electrode and a P-type electrode, the projection of the N-type electrode in the thickness direction of the silicon substrate is located in the N-type doped region, and the projection of the P-type electrode in the thickness direction of the silicon substrate is located in the P-type doped region; the area ratio of a single P-type electrode to a single P-type doped region corresponding to the P-type electrode is 1: 4.8-5.2. The back contact cell provided by the utility model can effectively enhance the secondary or multiple absorption of photons by the backlight surface, improve the short-circuit current of the cell, reduce the series resistance, and improve the fill factor, thereby effectively improving the conversion efficiency of the cell on the whole.

Description

Technical Field

[0001] This utility model relates to the field of solar cell technology, and in particular to a back contact battery, battery module and photovoltaic system. Background Technology

[0002] Currently, back-contact (BC) solar cells are increasingly widely used in the mainstream photovoltaic market. Their structural feature is that alternating P-type and N-type doped regions are formed on the back side, and electrodes are printed on the P-type and N-type doped regions. The electrodes are also located on the back side of the cell, which allows the passivation and optical optimization of the front surface to be fully improved and optimized.

[0003] However, the arrangement of the P-type / N-type doped region and the electrode in existing back-contact solar cells is unreasonable, which affects the photoelectric conversion efficiency of the cell. Utility Model Content

[0004] The purpose of this invention is to address the existing technological limitations by providing a back-contact battery, battery module, and photovoltaic system. The back-contact battery of this invention effectively enhances the secondary or multiple absorption of photons by the back surface, increases the battery short-circuit current, reduces series resistance, and improves the fill factor, thereby effectively improving the overall battery conversion efficiency.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] First, this utility model provides a back contact battery, comprising:

[0007] A silicon substrate having a light-receiving surface and a back-lighting surface disposed opposite to each other;

[0008] The backlight surface is provided with a doped layer and an electrode layer in sequence along the direction away from the light-receiving surface;

[0009] The doped layer includes alternating N-type doped regions and P-type doped regions;

[0010] The electrode layer includes an N-type electrode and a P-type electrode, wherein the projection of the N-type electrode in the thickness direction of the silicon substrate is located within the N-type doped region, and the projection of the P-type electrode in the thickness direction of the silicon substrate is located within the P-type doped region.

[0011] The area ratio between a single P-type electrode and the single P-type doped region corresponding to the P-type electrode is 1:4.8 to 5.2.

[0012] In some embodiments, the area ratio between a single N-type electrode and the single N-type doped region corresponding to the N-type electrode is 1:1.1 to 1.5.

[0013] In some embodiments, the area ratio between a single N-type electrode and a single P-type electrode is 1:1 to 1.5.

[0014] In some embodiments, the thickness of the electrode layer is 0.1 μm to 15 μm.

[0015] In some embodiments, both the N-type electrode and the P-type electrode are interdigitated structures. The interdigitated structure includes a first collecting portion extending along a first direction and a second collecting portion extending along a second direction. A plurality of second collecting portions are arranged at intervals along the first direction on the same first collecting portion. The first direction and the second direction are intersected. The width of the second collecting portion in the first direction is 80 μm to 105 μm.

[0016] In some embodiments, the contact resistivity of the P-type electrode is 0.003 Ω·cm. 2 ~0.1Ω·cm 2 The contact resistivity of the N-type electrode is 0.0005 Ω·cm. 2 ~0.1Ω·cm 2 .

[0017] In some embodiments, the N-type electrode and / or the P-type electrode is any one of Ag layer, Cu layer, and Au layer, or a composite layer formed by stacking at least two of Ag layer, Cu layer, and Au layer.

[0018] In some embodiments, a back passivation layer is provided between the silicon substrate and the doped layer, a transparent conductive layer is provided between the doped layer and the electrode layer, and a front passivation layer and an antireflection layer are sequentially provided on the light-receiving surface in a direction away from the back light surface.

[0019] Secondly, this utility model provides a back contact battery, comprising:

[0020] A silicon substrate having a light-receiving surface and a back-lighting surface disposed opposite to each other;

[0021] The backlight surface is provided with a doped layer and an electrode layer in sequence along the direction away from the light-receiving surface;

[0022] The doped layer includes alternating N-type doped regions and P-type doped regions;

[0023] The electrode layer includes N-type electrodes and P-type electrodes, and the projection of the N-type electrode in the thickness direction of the silicon substrate is located within the N-type doped region, and the projection of the P-type electrode in the thickness direction of the silicon substrate is located within the P-type doped region; the ratio between the total area of ​​all P-type electrodes and the total area of ​​all P-type doped regions is 1:4.8 to 5.2.

[0024] In some embodiments, the ratio between the total area of ​​all the N-type electrodes and the total area of ​​all the N-type doped regions is 1:1.1 to 1.5.

[0025] Furthermore, this utility model provides a battery assembly, including the aforementioned back contact battery.

[0026] Finally, this utility model provides a photovoltaic system including the aforementioned battery components.

[0027] The beneficial effects of this utility model are as follows:

[0028] In this invention, by controlling the area ratio between a single P-type electrode and its corresponding single P-type doped region to be 1:4.8 to 5.2, the area between the P-type electrode and its corresponding P-type doped region is adjusted so that the P-type electrode has an appropriate coverage ratio relative to the P-type doped region. The P-type electrode reflects the light incident from the light-receiving surface of the silicon substrate and then into the silicon substrate, effectively enhancing the secondary or multiple absorption of photons by the backlight surface. By adjusting the area of ​​the P-type electrode itself relative to the P-type doped region, the utilization rate of light is improved more precisely and effectively, and the short-circuit current of the battery is effectively increased. At the same time, within this ratio range, the P-type electrode can provide sufficient carrier transport channels, reduce series resistance, and improve the fill factor, thereby effectively improving the overall battery conversion efficiency. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of a back contact battery according to an embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of the back structure of a back contact battery according to an embodiment of the present invention.

[0031] In the picture:

[0032] 1. Silicon substrate; 11. Light-receiving surface; 12. Backlight-receiving surface;

[0033] 2. Doped layer; 21. N-type doped region; 22. P-type doped region;

[0034] 3. Electrode layer; 31. N-type electrode; 311. N-type first collection section; 312. N-type second collection section; 32. P-type electrode; 321. P-type first collection section; 322. P-type second collection section;

[0035] 4. Back passivation layer; 5. Front passivation layer; 6. Anti-reflection layer. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present utility model, and should not be construed as limiting the present utility model. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining the present utility model and are not intended to limit the present utility model.

[0037] In the description of this specification, unless otherwise expressly specified and limited, the term "above" or "below" a second feature may include direct contact between the first and second features, or contact between the first and second features not in direct contact but through another feature between them.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this specification, "a plurality of" or "several" means two or more, unless otherwise explicitly specified.

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0040] First, see Figure 1 As shown, this utility model provides a back contact battery, comprising:

[0041] Silicon substrate 1 has a light-receiving surface 11 and a backlight surface 12 disposed opposite to each other;

[0042] A doped layer 2 and an electrode layer 3 are sequentially disposed on the backlight surface 12 along the direction away from the light-receiving surface 11;

[0043] Doped layer 2 includes alternating N-type doped regions 21 and P-type doped regions 22;

[0044] The electrode layer 3 includes an N-type electrode 31 and a P-type electrode 32, and the projection of the N-type electrode 31 in the thickness direction of the silicon substrate 1 is located in the N-type doped region 21, and the projection of the P-type electrode 32 in the thickness direction of the silicon substrate 1 is located in the P-type doped region 22.

[0045] The area ratio between a single P-type electrode 32 and the single P-type doped region 22 corresponding to the P-type electrode 32 is 1:4.8 to 5.2.

[0046] In terms of thickness, the silicon substrate 1 includes a light-receiving surface 11 and a backlight surface 12 disposed opposite to each other. The light-receiving surface 11 generally refers to the side that receives light, and its surface may also be provided with passivation layers, antireflection layers 6, etc., which are common in the art, but are not limited thereto. It should be noted that in some embodiments, the backlight surface 12 may also absorb the light incident through the backlight surface 12, thereby generating a photocurrent.

[0047] In this embodiment, by controlling the area ratio between a single P-type electrode 32 and the corresponding single P-type doped region 22 to be 1:4.8 to 5.2, the area between the P-type electrode 32 and its corresponding P-type doped region 22 is adjusted so that the P-type electrode 32 has an appropriate coverage ratio relative to the P-type doped region 22. The P-type electrode 32 reflects the light incident from the light-receiving surface 11 of the silicon substrate 1 and then into the silicon substrate 1, effectively enhancing the secondary or multiple absorption of photons by the backlight surface 12. By adjusting the area of ​​the P-type electrode 32 relative to the P-type doped region 22, the utilization rate of light is improved more precisely and effectively, and the short-circuit current of the battery is effectively increased. At the same time, within this ratio range, the P-type electrode 32 can provide sufficient carrier transport channels, reduce series resistance, and improve the fill factor, thereby effectively improving the overall battery conversion efficiency.

[0048] For example, the area ratio between a single P-type electrode 32 and the single P-type doped region 22 corresponding to the P-type electrode 32 is 1:4.8, 1:4.9, 1:5.0, 1:5.1 or 1:5.2, but is not limited thereto.

[0049] When the coverage area of ​​the P-type electrode 32 relative to the P-type doped region 22 is too large, the shading area is too large, and the negative impact caused by the reduced light absorption of the backlight surface 12 is too great, which can easily lead to a decrease in conversion efficiency.

[0050] When the coverage area of ​​the P-type electrode 32 relative to the P-type doped region 22 is too small, the enhancement effect of the P-type electrode 32 on the secondary or multiple absorption of photons by the backlight surface 12 is reduced, and the series resistance increases, which can easily lead to a decrease in conversion efficiency.

[0051] In some embodiments, the area ratio between a single N-type electrode 31 and the single N-type doped region 21 corresponding to the N-type electrode 31 is 1:1.1 to 1.5.

[0052] For example, the area ratio between a single N-type electrode 31 and the single N-type doped region 21 corresponding to the N-type electrode 31 is 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5, but is not limited thereto.

[0053] On the one hand, by controlling the area ratio between a single N-type electrode 31 and the single N-type doped region 21 corresponding to the N-type electrode 31 to be 1:1.1 to 1.5, the area between the N-type electrode 31 and its corresponding N-type doped region 21 is adjusted so that the N-type electrode 31 has an appropriate coverage ratio relative to the N-type doped region 21. The P-type electrode 32 reflects the light incident from the light-receiving surface 11 of the silicon substrate 1 and then into the silicon substrate 1, effectively enhancing the secondary or multiple absorption of photons by the backlight surface 12. By adjusting the area of ​​the N-type electrode 31 itself relative to the N-type doped region 21, the utilization rate of light is improved more precisely and effectively, and the short-circuit current of the battery is effectively increased. At the same time, within this ratio range, the N-type electrode 31 can provide sufficient carrier transport channels, reduce series resistance, and improve the fill factor, thereby effectively improving the overall battery conversion efficiency. On the other hand, since the width of the P-type doped region 22 in the battery is usually greater than the width of the N-type doped region 21, based on controlling the area ratio between a single P-type electrode 32 and the single P-type doped region 22 corresponding to the P-type electrode 32 to be 1:4.8 to 5.2, the area ratio between a single N-type electrode 31 and the single N-type doped region 21 corresponding to the N-type electrode 31 to be 1:1.1 to 1.5 is controlled. The two work together to help balance the collection of electron-hole pairs and further improve the battery conversion efficiency.

[0054] In some embodiments, the area ratio between a single N-type electrode 31 and a single P-type electrode 32 is 1:1 to 1.5.

[0055] For example, the area ratio between a single N-type electrode 31 and a single P-type electrode 32 is 1:1, 1:1.1, 1:1.15, 1:1.2, 1:1.3, 1:1.35, 1:1.4, 1:1.45 or 1:1.5, but is not limited thereto.

[0056] By adjusting the area ratio between the P-type electrode 32 and the N-type electrode 31, the collection of electron-hole pairs is balanced, thereby further improving the battery conversion efficiency.

[0057] Understandably, on the back surface 12 of the same back contact battery, the area ratio between different P-type electrodes 32 and their corresponding P-type doped regions 22 can be the same or different. Similarly, the area ratio between different N-type electrodes 31 and their corresponding N-type doped regions 21 can be the same or different. Preferably, on the back surface 12 of the same back contact battery, the area ratio between different P-type electrodes 32 and their corresponding P-type doped regions 22 is the same, and the area ratio between different N-type electrodes 31 and their corresponding N-type doped regions 21 is the same.

[0058] Secondly, see Figure 1 As shown, this embodiment also provides a back contact battery, including:

[0059] Silicon substrate 1 has a light-receiving surface 11 and a backlight surface 12 disposed opposite to each other;

[0060] A doped layer 2 and an electrode layer 3 are sequentially disposed on the backlight surface 12 along the direction away from the light-receiving surface 11;

[0061] Doped layer 2 includes alternating N-type doped regions 21 and P-type doped regions 22;

[0062] The electrode layer 3 includes an N-type electrode 31 and a P-type electrode 32, and the projection of the N-type electrode 31 in the thickness direction of the silicon substrate 1 is located in the N-type doped region 21, and the projection of the P-type electrode 32 in the thickness direction of the silicon substrate 1 is located in the P-type doped region 22.

[0063] The ratio between the total area of ​​all P-type electrodes 32 and the total area of ​​all P-type doped regions 22 is 1:4.8 to 5.2.

[0064] For example, the ratio between the total area of ​​all P-type electrodes 32 and the total area of ​​all P-type doped regions 22 is 1:4.8, 1:4.9, 1:5.0, 1:5.1 or 1:5.2, but is not limited thereto.

[0065] This ensures that the total area of ​​all P-type electrodes 32 has an appropriate coverage ratio relative to the total area of ​​all P-type doped regions 22. By using the P-type electrodes 32 to reflect the light incident from the light-receiving surface 11 of the silicon substrate 1 and then into the silicon substrate 1, the secondary or multiple absorption of photons by the backlight surface 12 is effectively enhanced. By adjusting the area of ​​the P-type electrodes 32 relative to the P-type doped regions 22, the utilization rate of light is improved more precisely and effectively, and the short-circuit current of the battery is effectively increased. At the same time, within this ratio range, the P-type electrodes 32 can provide sufficient carrier transport channels, reduce series resistance, and improve the fill factor, thereby effectively improving the overall battery conversion efficiency.

[0066] In some embodiments, the ratio between the total area of ​​all N-type electrodes 31 and the total area of ​​all N-type doped regions 21 is 1:1.1 to 1.5.

[0067] For example, the ratio between the total area of ​​all N-type electrodes 31 and the total area of ​​all N-type doped regions 21 is 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5, but is not limited thereto.

[0068] This ensures that the N-type electrode 31 has an appropriate coverage ratio. Within this ratio range, the N-type electrode 31 can provide sufficient carrier transport channels, reduce series resistance, improve fill factor, and thus effectively improve battery conversion efficiency.

[0069] In some embodiments, both the N-type electrode 31 and the P-type electrode 32 are interdigitated structures. The interdigitated structure includes a first collecting portion extending along a first direction and a second collecting portion extending along a second direction. The first direction and the second direction are intersected. A plurality of second collecting portions are arranged at intervals along the first direction on the same first collecting portion. The width W of the second collecting portion in the first direction is 80 μm to 105 μm.

[0070] The first direction and the second direction intersect. In one embodiment, the first direction may be a horizontal direction and the second direction may be a vertical direction, wherein the first direction and the second direction are perpendicular to each other. It is understood that in other embodiments, the first direction and the second direction may not be perpendicular, and the first direction and the second direction may be any other direction, such as the diagonal direction of the rectangular silicon substrate 1, but are not limited thereto.

[0071] For clarity, see [link to documentation]. Figure 2 As shown, the first collecting section and the second collecting section corresponding to the N-type electrode 31 are respectively referred to as N-type first collecting section 311 and N-type second collecting section 312, and the first collecting section and the second collecting section corresponding to the P-type electrode 32 are respectively referred to as P-type first collecting section 321 and P-type second collecting section 322.

[0072] Understandably, as the N-type doped region 21 and the P-type doped region 22 are arranged alternately in the doped layer 2, the N-type electrode 31 and the P-type electrode 32 are also arranged alternately. Specifically, the N-type first collection part 311 and the P-type first collection part 321 are arranged alternately in the second direction, and the adjacent N-type second collection part 312 and the P-type second collection part 322 are arranged alternately in the first direction.

[0073] For example, the width of the second collecting portion in the first direction is 80μm, 85μm, 88μm, 90μm, 92μm, 95μm, 98μm, 100μm, or 105μm, but is not limited thereto. It is understood that on the same battery, the widths of the N-type second collecting portion 312 and the P-type second collecting portion 322 may be the same or different.

[0074] By adjusting the width of the second collecting section, the second collecting section has sufficient carrier transport channels, reducing the series resistance, while avoiding an excessively large light-shielding area on the backlight surface 12. As a result, the battery as a whole exhibits lower series resistance and higher short-circuit current, thereby improving the battery conversion efficiency.

[0075] In some embodiments, the contact resistivity of the P-type electrode 32 is 0.003 Ω·cm. 2 ~0.1Ω·cm 2 The contact resistivity of the N-type electrode 31 is 0.0005 Ω·cm. 2 ~0.1Ω·cm2 .

[0076] By controlling the contact resistivity and reducing the series resistance, the battery conversion efficiency can be further improved.

[0077] For example, the contact resistivity of the P-type electrode 32 is 0.003 Ω·cm. 2 0.005Ω·cm 2 0.01Ω·cm 2 0.02Ω·cm 2 0.03Ω·cm 2 0.04Ω·cm 2 0.05Ω·cm 2 0.06Ω·cm 2 0.07Ω·cm 2 0.08Ω·cm 2 0.09Ω·cm 2 or 0.1Ω·cm 2 However, it is not limited to this.

[0078] For example, the contact resistivity of the N-type electrode 31 is 0.0005 Ω·cm. 2 0.001Ω·cm 2 0.003Ω·cm 2 0.005Ω·cm 2 0.008Ω·cm 2 0.01Ω·cm 2 0.02Ω·cm 2 0.03Ω·cm 2 0.04Ω·cm 2 0.05Ω·cm 2 0.06Ω·cm 2 0.07Ω·cm 2 0.08Ω·cm 2 0.09Ω·cm 2 or 0.1Ω·cm 2 However, it is not limited to this.

[0079] In some embodiments, the N-type electrode 31 and / or the P-type electrode 32 are any one of Ag layer, Cu layer, and Au layer, or are composite layers formed by stacking at least two of Ag layer, Cu layer, and Au layer.

[0080] For example, the composite layer may be formed by stacking an Ag layer and a Cu layer, or by stacking an Ag layer and an Au layer, or by stacking an Au layer and a Cu layer, but is not limited to these.

[0081] For example, the electrode layer 3 can be formed by screen printing or by electroplating.

[0082] The N-type electrode 31 and the P-type electrode 32 can be made of the same material layer or different material layers. Preferably, the N-type electrode 31 and the P-type electrode 32 are made of the same material layer.

[0083] Preferably, the N-type electrode 31 and the P-type electrode 32 are Ag layers, which helps to improve the back reflection effect.

[0084] Preferably, the N-type electrode 31 and the P-type electrode 32 are Cu layers, which helps to reduce material costs.

[0085] In some embodiments, see Figure 1 As shown, a back passivation layer 4 is provided between the silicon substrate 1 and the doped layer 2, and a transparent conductive layer (not shown) is provided between the doped layer 2 and the electrode layer 3. A front passivation layer 5 and an anti-reflection layer 6 are sequentially provided on the light-receiving surface 11 along the direction away from the back light surface 12.

[0086] In some embodiments, the silicon substrate 1 is N-type monocrystalline silicon or P-type monocrystalline silicon.

[0087] In some embodiments, the back passivation layer 4 includes a P-type passivation region and an N-type passivation region. The projection of the P-type passivation region onto the thickness direction of the silicon substrate 1 is located within the P-type doped region 22, and the projection of the N-type passivation region onto the thickness direction of the silicon substrate 1 is located within the N-type doped region 21. The P-type passivation region is an intrinsic hydrogenated amorphous silicon material layer, and the N-type passivation region is made of one of the following: an intrinsic hydrogenated amorphous silicon material layer, a silicon dioxide material layer, or a silicon nitride material layer. By passivating the interface through the back passivation layer 4, the carrier transport efficiency is improved, recombination losses during transport are reduced, and the conversion efficiency is further improved.

[0088] A transparent conductive layer is provided between the doped layer 2 and the electrode layer 3. The transparent conductive layer, in conjunction with the area coverage ratio between the electrode layer 3 and the doped layer 2 of this invention, can further improve the light utilization rate and the carrier transport efficiency, especially the hole transport efficiency, thereby further improving the conversion efficiency.

[0089] In some embodiments, the P-type doped region 22 is a layer of hydrogenated amorphous silicon material, and the N-type doped region 21 is a layer of hydrogenated amorphous silicon material or a layer of polycrystalline silicon material.

[0090] In some embodiments, the antireflection layer 6 is a SiO2 layer or a SiN layer. x layer, SiNO x The layer can be any one of the materials, or it can be composed of SiO2 layers, SiN layers, etc. x layer, SiNO xThe composite layer consists of at least two layers stacked together, wherein the thickness of the antireflection layer 6 can be 60 nm to 130 nm.

[0091] Secondly, this utility model provides a battery assembly, including the aforementioned back contact battery.

[0092] Furthermore, this utility model provides a photovoltaic system including the aforementioned battery module.

[0093] Multiple battery modules can be connected in series or parallel through a junction box to form a photovoltaic system. This photovoltaic system can be used in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, and solar buildings, but is not limited to these.

[0094] Compared to conventional back-contact batteries, for example, with the remaining structural settings being the same, taking a back-contact battery where the area ratio between a single P-type electrode and its corresponding single P-type doped region is 1:6 to 20, and the area ratio between a single N-type electrode and its corresponding single N-type doped region is 1:4 to 20 (which is also a common conventional back-contact battery design), experiments have shown that, compared to the aforementioned conventional back-contact batteries, the battery using the area coverage ratio range between the electrode layer and the doped layer of this invention can achieve a conversion efficiency increase of at least 3.2%.

[0095] In the description of this specification, references to terms such as "some embodiments," "exemplary," "example," or "for example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0096] Of course, the above illustrations are only preferred embodiments of this utility model and are not intended to limit the scope of application of this utility model. Therefore, any equivalent changes made to the principle of this utility model should be included within the protection scope of this utility model.

Claims

1. A back-contact battery, characterized in that, include: A silicon substrate having a light-receiving surface and a back-lighting surface disposed opposite to each other; The backlight surface is provided with a doped layer and an electrode layer in sequence along the direction away from the light-receiving surface; The doped layer includes alternating N-type doped regions and P-type doped regions; The electrode layer includes an N-type electrode and a P-type electrode, wherein the projection of the N-type electrode in the thickness direction of the silicon substrate is located within the N-type doped region, and the projection of the P-type electrode in the thickness direction of the silicon substrate is located within the P-type doped region. The area ratio between a single P-type electrode and the single P-type doped region corresponding to the P-type electrode is 1:4.8 to 5.

2.

2. A back contact battery according to claim 1, characterized in that, The area ratio between a single N-type electrode and the single N-type doped region corresponding to the N-type electrode is 1:1.1 to 1.

5.

3. A back contact battery according to claim 1, characterized in that, The area ratio between a single N-type electrode and a single P-type electrode is 1:1 to 1.

5.

4. A back contact battery according to claim 1, characterized in that, Both the N-type electrode and the P-type electrode have an interdigitated structure. The interdigitated structure includes a first collecting part extending along a first direction and a second collecting part extending along a second direction. A plurality of second collecting parts are arranged at intervals along the first direction on the same first collecting part. The first direction and the second direction are intersected. The width of the second collecting part in the first direction is 80μm to 105μm.

5. A back contact battery according to claim 1, characterized in that, The contact resistivity of the P-type electrode is 0.003 Ω·cm. 2 ~0.1Ω·cm 2 The contact resistivity of the N-type electrode is 0.0005 Ω·cm. 2 ~0.1Ω·cm 2 .

6. A back contact battery according to claim 1, characterized in that, The N-type electrode and / or the P-type electrode are any one of Ag layer, Cu layer, and Au layer, or are composite layers formed by stacking at least two of Ag layer, Cu layer, and Au layer.

7. A back contact battery according to claim 1, characterized in that, A back passivation layer is provided between the silicon substrate and the doped layer, a transparent conductive layer is provided between the doped layer and the electrode layer, and a front passivation layer and an anti-reflection layer are sequentially provided on the light-receiving surface along the direction away from the back light surface.

8. A back-contact battery, characterized in that, include: A silicon substrate having a light-receiving surface and a back-lighting surface disposed opposite to each other; The backlight surface is provided with a doped layer and an electrode layer in sequence along the direction away from the light-receiving surface; The doped layer includes alternating N-type doped regions and P-type doped regions; The electrode layer includes an N-type electrode and a P-type electrode, wherein the projection of the N-type electrode in the thickness direction of the silicon substrate is located within the N-type doped region, and the projection of the P-type electrode in the thickness direction of the silicon substrate is located within the P-type doped region. The ratio between the total area of ​​all the P-type electrodes and the total area of ​​all the P-type doped regions is 1:4.8 to 5.

2.

9. A back contact battery according to claim 8, characterized in that, The ratio between the total area of ​​all the N-type electrodes and the total area of ​​all the N-type doped regions is 1:1.1 to 1.

5.

10. A battery assembly, characterized in that, Includes a back contact battery according to any one of claims 1 to 7, or includes a back contact battery according to any one of claims 8 to 9.

11. A photovoltaic system, characterized in that, Includes the battery assembly according to claim 10.

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