Back contact battery, battery assembly and photovoltaic system

Abstract

The invention relates to the technical field of solar cells, and particularly discloses a back contact cell, a cell assembly and a photovoltaic system, the cell comprises a substrate, the substrate is provided with a first surface, a second surface and a side surface, the first surface and the second surface are oppositely arranged, and the side surface is respectively connected with the first surface and the second surface; the doping layer is arranged on the second surface; the TCO layer comprises a main body part and a micro electric leakage channel part, the main body part is arranged on one side, opposite to the substrate, of the doping layer, the micro electric leakage channel part extends to the outer side of the side surface from at least part of the edge of the main body part along a first direction, and the first direction is a direction from the second surface to the first surface. According to the back contact battery, the hot spot effect can be reduced, the local overheating phenomenon caused by charge accumulation is avoided, and the overall reliability and safety of the battery are improved.

Description

Technical Field

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

[0002] In the current field of photovoltaic technology, back-contact cells, as a highly efficient and widely used solar cell structure, have long been a focus of research on their performance and stability. However, in actual operation, back-contact cells are often affected by the hot spot effect, which is particularly pronounced at the cell's edges. This hot spot effect can cause localized heating in the cell, which not only reduces the cell's conversion efficiency but can also cause localized overheating, potentially damaging the cell structure and even posing a safety hazard.

[0003] Currently, the primary approach to effectively mitigate the negative impact of the hot spot effect on back-contact cells is to modify the structure of the doped layers. Specifically, a specific structure is constructed between different doped regions to form micro-leakage channels, thereby mitigating the hot spot effect. These micro-leakage channels provide a low-impedance path for charge to escape from the battery, thereby preventing localized overheating caused by charge accumulation. However, this design is not without limitations. Firstly, when using doped layers as micro-leakage channels, charge transport exhibits significant selectivity due to the inherent properties of semiconductor materials. If a pn junction is formed, due to its unidirectional conductivity, charge cannot freely flow through this region under a specific voltage bias, thus failing to achieve its intended function and forming an effective micro-leakage channel. Secondly, existing improvement approaches often overlook the hot spot effect at the cell's edge regions, failing to specifically improve their hot spot resistance. Consequently, the battery's reliability and safety in combating the hot spot effect are significantly compromised, making it difficult to reliably guarantee normal operation and safe use. Summary of the Invention

[0004] The purpose of the present invention is to provide a back-contact battery, battery assembly and photovoltaic system in response to the existing technical status.

[0005] The back-contact battery of the present invention can reduce the hot spot effect, avoid local overheating caused by charge accumulation, and improve the overall reliability and safety of the battery.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] First, the present invention provides a back contact battery, comprising:

[0008] A substrate having a first surface, a second surface, and a side surface, wherein the first surface and the second surface are arranged opposite to each other, and the side surface is connected to the first surface and the second surface respectively;

[0009] a doping layer disposed on the second surface;

[0010] The TCO layer includes a main body portion and a micro leakage channel portion, wherein the main body portion is arranged on the side of the doping layer facing away from the substrate, and the micro leakage channel portion extends from at least a portion of the edge of the main body portion along a first direction to the outside of the side surface, and the first direction is the direction from the second surface toward the first surface.

[0011] In some embodiments, the thickness of the micro leakage channel portion decreases along the first direction.

[0012] In some embodiments, the micro leakage channel portion is provided with a first end and a second end at both ends of the first direction, and the second end is provided at an end of the micro leakage channel portion away from the main body portion, wherein the thickness of the first end is H, and the thickness h of the second end is 0<h≤10%H.

[0013] In some embodiments, H is 70 nm to 90 nm.

[0014] In some embodiments, a functional layer is further provided on the first surface, and the micro leakage channel portion extends outside the sidewall of the functional layer.

[0015] In some embodiments, the functional layer includes one or more of a passivation layer and an anti-reflection layer.

[0016] In some embodiments, the length of the micro leakage channel portion along the first direction is L, wherein,

[0017] 0.1×S≤L≤0.85×S,

[0018] Wherein, S is the relative distance in the first direction between the side of the functional layer facing away from the first surface and the end of the micro leakage channel portion away from the first surface.

[0019] In some embodiments, the main body includes a transverse portion, a surface of the transverse portion is parallel to a surface of the second surface, and a thickness of the transverse portion is greater than or equal to a thickness of the micro leakage channel portion at an end away from the first surface.

[0020] In some embodiments, the side includes a first side, a second side, a third side and a fourth side connected in sequence, the first side and the third side are arranged along a second direction, the second side and the fourth side are arranged along a third direction, the second direction and the third direction are arranged to intersect, and the micro leakage channel portion is arranged on the outside of at least one of the first side, the second side, the third side and the fourth side.

[0021] In some embodiments, the second surface has a plurality of first areas and second areas alternately arranged along the second direction, the main body includes a first TCO segment provided in the first area and a second TCO segment provided in the second area, the first TCO segment and the second TCO segment extend along the third direction, the doped layer includes a first doped layer and a second doped layer with opposite polarities, at least a portion of the first TCO segment is conductively connected to the first doped layer, and at least a portion of the second TCO segment is conductively connected to the second doped layer.

[0022] In some embodiments, the two end regions of the main body in the second direction are referred to as a first edge region and a second edge region, and the portions of the main body located in the first edge region and above the first edge region are each independently referred to as the first TCO segment or the second TCO segment, and the first edge region is located at an end of the main body close to the first side surface.

[0023] The micro leakage channel portion includes a first unit provided on the first side surface, the first unit being connected to the same first TCO segment or the same second TCO segment of the main body located in the first edge region; and / or,

[0024] The micro leakage channel portion includes a third unit provided on the third side surface, and the third unit is connected to the same first TCO segment or the same second TCO segment of the main body located in the second edge region.

[0025] In some embodiments, the micro leakage channel portion includes a second unit provided on the second side surface, the second unit including a second unit A connected to the first TCO segment and / or a second unit B connected to the second TCO segment; and / or,

[0026] The micro leakage channel portion includes a fourth unit provided on the fourth side surface, and the fourth unit includes a fourth unit A connected to the first TCO segment and / or a fourth unit B connected to the fourth TCO segment.

[0027] In some embodiments, the first doped layer is disposed in the first region, and the second doped layer includes a first segment disposed in the first region and a second segment extending to the second region.

[0028] The first segment is arranged on the side of the first doped layer facing away from the substrate, and an insulating protective layer is provided between the first doped layer and the second doped layer. A channel is opened between the first segment and the insulating protective layer. The first TCO segment includes a contact portion arranged in the channel, the contact portion is in contact with the first doped layer, and the second segment is in contact with the second TCO segment.

[0029] In some embodiments, a first passivation layer is provided between the first doping layer and the substrate, and / or,

[0030] A second passivation layer is provided on the side of the second doping layer facing the substrate. The second passivation layer includes a first portion provided in the first region and a second portion extending to the second region. The first portion is provided between the insulating protection layer and the second doping layer.

[0031] Secondly, the present invention provides a battery assembly, including the above-mentioned back contact battery.

[0032] Furthermore, the present invention provides a photovoltaic system including the above-mentioned battery assembly.

[0033] The beneficial effects of the present invention are:

[0034] The TCO layer in the present invention includes a main body portion provided on the side of the doping layer facing away from the substrate and a micro-leakage channel portion extending from the edge of the main body portion along a first direction to the outside of the side surface, thereby forming a micro-leakage path on the side wall of the battery. Regardless of the conductive area of ​​which polarity the side wall of the battery is located, when shadowing occurs, the excess charge can be recombined with the substrate charge through the micro-leakage channel portion, thereby reducing the hot spot effect and avoiding local overheating caused by charge accumulation. At the same time, compared with the method of using a doping layer as a micro-leakage channel structure, the present invention can avoid the selectivity of charge transfer, ensure the reliability and safety of the battery when dealing with the hot spot effect, and effectively increase the anti-hot spot performance of the edge area of the battery, further improving the overall reliability and safety of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the edge structure of the back contact battery of the present invention along the second direction cross section.

[0036] Figure 2 Schematic diagram of another edge structure of the back contact battery of the present invention along the second direction cross section.

[0037] Figure 3Schematic diagram of the edge structure of the back contact battery of the present invention along the third direction.

[0038] Figure 4 It is a schematic diagram of another edge structure of the back contact battery of the present invention along the third direction section.

[0039] Figure 5 This is a top view of the back contact battery of the present invention.

[0040] Figure 6 It is a schematic diagram of a partial structure when the micro leakage channel portion of the present invention includes a second unit A and a second unit B (there is a gap between the two).

[0041] Figure 7 It is a schematic diagram of the local structure when the second unit A and the second unit B exist in the micro leakage channel portion of the present invention (the two are partially in contact).

[0042] Figure 8 It is a schematic diagram of the local structure when the micro leakage channel portion of the present invention has a third unit A and a second unit B (there is a gap between the two).

[0043] Figure 9 It is a schematic diagram of the local structure when the third unit A and the second unit B exist in the micro leakage channel portion of the present invention (the two are partially in contact). DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0045] In the description of the present invention, the terms "first," "second," etc. are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of the described features. In the description of the present invention, "plurality" or "several" means two or more, unless otherwise specifically defined.

[0046] In the description of the present invention, unless otherwise clearly stipulated and limited, a first feature being “above” or “below” a second feature may include the first feature and the second feature being in direct contact, or may include the first feature and the second feature not being in direct contact but being in contact through another feature between them.

[0047] First, see Figure 1 、 Figure 2 and Figure 5 As shown, the present invention provides a back contact battery, comprising:

[0048] The substrate 1 has a first surface 11, a second surface 12 and a side surface 13. The first surface 11 and the second surface 12 are arranged opposite to each other, and the side surface 13 is connected to the first surface 11 and the second surface 12 respectively.

[0049] a doping layer 3 disposed on the second surface 12;

[0050] The TCO layer 2 includes a main body portion 21 and a micro leakage channel portion 22. The main body portion 21 is arranged on the side of the doped layer 3 facing away from the substrate 1. The micro leakage channel portion 22 extends from at least a portion of the edge of the main body portion 21 along a first direction to the outside of the side surface 13. The first direction is the direction from the second surface 12 toward the first surface 11.

[0051] It can be understood that the substrate 1 has a first surface 11 and a second surface 12 that are relatively arranged, wherein one is the light-receiving surface (usually referred to as the front side of the substrate 1), and the other is the backlight surface (usually referred to as the back side of the substrate 1), and each side wall around the edge of the substrate 1 is a side surface 13. In this specification, the first surface 11 is the light-receiving surface and the second surface 12 is the backlight surface, wherein the light-receiving surface generally refers to the side that receives light, and its surface may also be provided with a passivation layer, an anti-reflection layer, etc. that are common in the art, but is not limited to this. In some embodiments, the light-receiving surface may also be provided with a velvet surface. It should be noted that in some embodiments, light incident through the backlight surface may also be absorbed to generate a photocurrent. In addition, in actual application, the embodiment of the present invention does not specifically limit the material and conductivity type of the substrate 1. Exemplarily, the substrate 1 can be a silicon substrate 1, such as single crystal silicon, microcrystalline silicon, polycrystalline silicon or amorphous silicon, or a germanium silicon substrate 1, a germanium substrate 1 or a gallium arsenide substrate 1, but is not limited thereto, and its conductivity type can be N-type or P-type.

[0052] It is understandable that in conventional batteries, the transparent conductive layer will be removed from the area at the edge of the back of the battery after deposition. In the present invention, the edge of the main body 21 of the TCO layer 2 extends to the edge of the second surface 12 and extends along the first direction to the outside of the side surface 13 to form a micro leakage channel.

[0053] The TCO layer 2 in the present invention includes a main body 21 arranged on the side of the doping layer 3 facing away from the substrate 1 and a micro-leakage channel portion 22 extending from the edge of the main body 21 along the first direction to the outside of the side 13, thereby forming a micro-leakage path on the side wall of the battery. No matter which polarity of the conductive area the side wall of the battery is located in, when shadowing occurs, the excess charge can be recombined with the charge of the substrate 1 through the micro-leakage channel portion 22, thereby reducing the hot spot effect and avoiding local overheating caused by charge accumulation. At the same time, compared with the method of using the doping layer 3 as the structure of the micro-leakage channel, the present invention can avoid the selectivity of charge transfer, ensure the reliability and safety of the battery when dealing with the hot spot effect, and effectively increase the anti-hot spot performance of the edge area of the battery. After testing, the hot spot effect temperature of the edge of the battery of the present invention can be maintained within 100°C, further improving the overall reliability and safety of the battery.

[0054] In some embodiments, the TCO layer 2, i.e., the transparent conductive oxide (TCO) thin film layer, can be a single material layer or a composite material layer formed by stacking multiple single material layers. The material of the single material layer can be any one of ITO, IWO, and AZO.

[0055] In some embodiments, the first TCO segment 211 and / or the second TCO segment 212 may be a single material layer, or a composite TCO material layer formed by stacking multiple material layers.

[0056] In the first embodiment, the thickness of the micro leakage channel portion 22 remains relatively constant along the first direction.

[0057] In the second embodiment, see Figure 1 As shown, the thickness of the micro leakage channel portion 22 decreases along the first direction.

[0058] It can be understood that, in terms of the regularity of the decreasing trend, the decreasing trend of the thickness of the micro leakage channel portion 22 can be a linear decrease or a nonlinear decrease; in terms of the continuity of the decrease, the decreasing trend of the thickness of the micro leakage channel portion 22 can be a continuous decrease or a discontinuous decrease. For example, the side wall profile of the micro leakage channel facing away from the side surface 13 of the substrate 1 can be an inclined straight line, a stepped line, or an arc line, but is not limited thereto.

[0059] When the micro-leakage channel portion 22 is in effect, charges are transferred from the edge of the main body portion 21 to the micro-leakage channel portion 22. The thickness of the micro-leakage channel portion 22 decreases along the first direction. The thicker starting end has higher conductivity, which is conducive to rapid charge transmission. As the thickness gradually becomes thinner, the electric field distribution will change, forming a driving force that is conducive to the transmission of charges in a specific direction, which helps to guide the charge to be transmitted along the first direction, thereby reducing the hot spot effect and avoiding local overheating caused by charge accumulation. At the same time, the decreasing thickness setting of the micro-leakage channel portion 22 is also conducive to reducing the amount of TCO material used, reducing material costs, and facilitating the industrial production of products.

[0060] In some embodiments, see Figure 2 As shown, the micro leakage channel portion 22 has a first end 221 and a second end 222 at both ends in the first direction, and the second end 222 is located at the end of the micro leakage channel portion 22 away from the main body portion 21. The thickness of the first end 221 is H, and the thickness h of the second end 222 is 0<h≤10%H.

[0061] The second end 222 having a smaller thickness is provided to reduce costs and to form a sufficient driving force for transferring charges in a specific direction.

[0062] In some embodiments, H is 70 nm to 90 nm.

[0063] Illustratively, H is 70 nm, 72 nm, 75 nm, 78 nm, 80 nm, 82 nm, 85 nm, 88 nm, or 90 nm, but is not limited thereto.

[0064] In some embodiments, see Figure 1 and Figure 2 As shown, a functional layer 6 is further provided on the first surface 11 , and the micro leakage channel portion 22 extends outside the side wall of the functional layer 6 .

[0065] In some embodiments, the functional layer 6 includes one or more of a passivation layer and an anti-reflection layer.

[0066] When the functional layer 6 includes a passivation layer and an anti-reflection layer, the anti-reflection layer is disposed on a side of the passivation layer facing away from the substrate 1 .

[0067] In some embodiments, see Figure 2 As shown, the length of the micro leakage channel portion 22 along the first direction is L, wherein,

[0068] 0.1×S≤L≤0.85×S,

[0069] Wherein, S is the relative distance in the first direction between the side of the functional layer 6 facing away from the first surface 11 and the end of the micro leakage channel portion 22 away from the first surface 11 .

[0070] The coverage of the micro leakage channel portion 22 should not be too high, otherwise it will easily affect the conversion efficiency. The coverage of the micro leakage channel portion 22 should not be too low, otherwise an effective leakage channel cannot be formed. When 0.1×S≤L≤0.85×S, it can achieve both higher conversion efficiency and better anti-hot spot performance, and the overall performance is better.

[0071] In some embodiments, the main body 21 includes a transverse portion, the surface of the transverse portion is parallel to the surface of the second surface 12 , and the thickness of the transverse portion is greater than or equal to the thickness of the end of the micro leakage channel portion 22 away from the first surface 11 .

[0072] The lateral portion has a larger thickness and higher electrical conductivity, which is beneficial to the transmission of carriers when the battery is working normally.

[0073] In some embodiments, the side surface 13 includes a first side surface 131, a second side surface 132, a third side surface 133, and a fourth side surface 134 connected in sequence, the first side surface 131 and the third side surface 133 are arranged along the second direction, the second side surface 132 and the fourth side surface 134 are arranged along the third direction, the second direction and the third direction are arranged to intersect, and the micro leakage channel portion 22 is arranged on the outside of at least one of the first side surface 131, the second side surface 132, the third side surface 133, and the fourth side surface 134.

[0074] It is understandable that the micro leakage channel portion 22 can be provided on any side surface 13 or on multiple side surfaces 13, and there is no limitation on this. Regardless of which side surface it is located on, the thickness of the micro leakage channel portion 22 can be set to decrease along the first direction, that is, a first end 221 and a second end 222 are provided.

[0075] In some embodiments, see Figure 1 and Figure 2 As shown, the second surface 12 has a plurality of first regions and second regions alternately arranged along the second direction. The main body 21 includes a first TCO segment 211 provided in the first region and a second TCO segment 212 provided in the second region. The first TCO segment 211 and the second TCO segment 212 extend along the third direction. The doped layer 3 includes a first doped layer 31 and a second doped layer 32 with opposite polarities. At least a portion of the first TCO segment 211 is conductively connected to the first doped layer 31, and at least a portion of the second TCO segment 212 is conductively connected to the second doped layer 32.

[0076] It is understood that, in terms of conductivity, the polarity of the first doping layer 31 and the polarity of the second doping layer 32 can be the same as or opposite to the polarity of the substrate 1, and it is only necessary to ensure that the polarity of the first doping layer 31 is opposite to the polarity of the second doping layer 32. The material of either the first doping layer 31 and / or the second doping layer 32 is single crystal silicon, polycrystalline silicon, or amorphous silicon doped with impurities of a Group III element (e.g., B, Ga, or In), and the material of the other is single crystal silicon, microcrystalline silicon, polycrystalline silicon, or amorphous silicon doped with impurities of a Group V element (e.g., P, As, Sb).

[0077] It can be understood that the first TCO segment 211 and the first doped layer 31 can be electrically connected through direct contact or indirect contact through a conductive material layer. The contact can be that a partial area of the first TCO segment 211 contacts the first doped layer 31, or the entire area of the first TCO segment 211 contacts the first doped layer 31. Similarly, the second TCO segment 212 and the second doped layer 32 can be electrically connected through direct contact or indirect contact through a conductive material layer. The contact can be that a partial area of the second TCO segment 212 contacts the second doped layer 32, or the entire area of the second TCO segment 212 contacts the second doped layer 32.

[0078] In some embodiments, see Figure 1 As shown, the two end regions of the main body 21 in the second direction are marked as the first edge region 223 and the second edge region 224. The portions of the main body 21 located in the first edge region 223 and on the first edge region 223 are independently the first TCO segment 211 or the second TCO segment 212. The first edge region 223 is located at one end of the main body 21 close to the first side surface 131.

[0079] The micro leakage channel portion 22 includes a first unit 225 disposed on the first side surface 131 . The first unit 225 is connected to the same first TCO segment 211 or the same second TCO segment 212 located in the first edge region 223 of the main body 21 .

[0080] It can be understood that the first unit 225 can be single or multiple and arranged at intervals. When there are multiple first units 225, the multiple first units 225 are connected to the same first TCO segment 211 or the same second TCO segment 212 located in the first edge area 223 of the main body 21.

[0081] In some embodiments, see Figure 2 As shown, the micro leakage channel portion 22 includes a third unit 227 provided on the third side surface 133 , and the third unit 227 is connected to the same first TCO segment 211 or the same second TCO segment 212 of the main body 21 located in the second edge region 224 .

[0082] It can be understood that the third unit 227 can be single or multiple and arranged at intervals. When there are multiple third units 227, the multiple third units 227 are connected to the same first TCO segment 211 or the same second TCO segment 212 of the main body 21 located in the second edge area 224.

[0083] In some embodiments, see Figure 4 、 Figure 6 and Figure 7 As shown, the micro leakage channel portion 22 includes a second unit 226 disposed on the second side surface 132 . The second unit 226 includes a second unit A 226A connected to the first TCO segment 211 and / or a second unit B 226B connected to the second TCO segment 212 .

[0084] It can be understood that the second unit 226 provided on the second side surface 132 may be only the second unit A226A connected to the first TCO segment 211, may be only the second unit B226B connected to the second TCO segment 212, or may include the second unit A226A and the second unit B226B. When the second unit 226 on the second side surface 132 includes the second unit A226A and the second unit B226B, there may be a gap between the second unit A226A and the second unit B226B (e.g., Figure 6 ), or there may be no interval (as shown in Figure 7 As shown), when there is no gap between the second unit A226A and the second unit B226B, there is local contact between the two, which can improve the anti-hot spot effect. The same is true for the fourth unit 228 below, which will not be repeated here.

[0085] In some embodiments, see Figure 3 、 Figure 8 and Figure 9 As shown, the micro leakage channel portion 22 includes a fourth unit 228 provided on the fourth side surface 134 , and the fourth unit 228 includes a fourth unit A 228A connected to the first TCO segment 211 and / or a fourth unit B 228B connected to the fourth TCO segment.

[0086] In some embodiments, the first doping layer 31 and the second doping layer 32 are alternately arranged along the second direction. In another embodiment, a portion of the second doping layer 32 may be stacked on a portion of the first doping layer 31. For details, see Figure 1 and Figure 2 As shown:

[0087] The first doping layer 31 is provided in the first region, and the second doping layer 32 includes a first segment 321 provided in the first region and a second segment 322 extending to the second region.

[0088] The first segment 321 is arranged on the side of the first doped layer 31 facing away from the substrate 1, and an insulating protective layer 4 is provided between the first doped layer 31 and the second doped layer 32. A channel is formed between the first segment 321 and the insulating protective layer 4. The first TCO segment 211 includes a contact portion provided in the channel, which contacts the first doped layer 31. The second segment 322 contacts the second TCO segment 212.

[0089] In some embodiments, the material of the insulating protection layer 4 can be PSG, SiN x 、SiO x Any one of .

[0090] In some embodiments, see Figure 1 and Figure 2 As shown, a first passivation layer 51 is provided between the first doping layer 31 and the substrate 1 .

[0091] In some embodiments, see Figure 1 and Figure 2 As shown, a second passivation layer 52 is provided on the side of the second doped layer 32 facing the substrate 1 . The second passivation layer 52 includes a first portion provided in the first region and a second portion extending to the second region. The first portion is provided between the insulating protection layer 4 and the second doped layer 32 .

[0092] By providing the first passivation layer 51 and the second passivation layer 52, the passivation effect and carrier transport effect are improved, which helps to improve the conversion efficiency of the battery. For example, the first passivation layer 51 and the second passivation layer 52 can be an intrinsic amorphous silicon layer or a tunneling oxide layer (such as silicon oxide, titanium oxide, etc.), but are not limited thereto.

[0093] Secondly, the present invention provides a battery assembly, including the above-mentioned back contact battery.

[0094] Furthermore, the present invention provides a photovoltaic system including the above-mentioned battery assembly.

[0095] The photovoltaic system includes a battery module, which includes the aforementioned solar cells. Multiple battery modules can be connected in series or in parallel via a junction box to form a photovoltaic system. This photovoltaic system can be used in photovoltaic power stations, such as ground-based power stations, rooftop power stations, and water-based power stations. It can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings, but is not limited to these.

[0096] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0097] Example 1

[0098] First, this embodiment discloses a back-contact battery, comprising:

[0099] The base has a first surface, a second surface and a side surface, wherein the first surface and the second surface are arranged opposite to each other, and the side surface is connected to the first surface and the second surface respectively;

[0100] a doping layer disposed on the second surface;

[0101] The TCO layer includes a main body portion and a micro leakage channel portion. The main body portion is arranged on the side of the doping layer facing away from the substrate. The micro leakage channel portion extends from at least a portion of the edge of the main body portion along a first direction to the outside of the side surface. The first direction is the direction from the second surface toward the first surface.

[0102] In this embodiment, the thickness of the micro leakage channel portion decreases gradually along the first direction.

[0103] Comparative Example 1

[0104] The difference between this embodiment and Example 1 is that the present comparative example does not include a micro leakage channel portion.

[0105] Hot spot test

[0106] Hot spot tests were performed on the cells prepared in Example 1 and Comparative Example 1 to observe their temperature changes.

[0107] Test results:

[0108] Experimental group Experimental results Example 1 The temperature is less than 100℃ after the local shading is stable for 1 hour Comparative Example 1 After the local shading is stable for 1 hour, the temperature is about 140℃

[0109] The experimental results show that compared with comparative example 1, the hot spot effect temperature of the battery edge of embodiment 1 of the present invention can be maintained within 100°C, the anti-hot spot performance is better, and the reliability and stability of the battery are better.

[0110] Throughout this specification, reference to terms such as "some embodiments," "exemplary," "example," or "for example" means that a specific feature, structure, material, or characteristic described in conjunction with an embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations 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 any one or more embodiments or examples.

[0111] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents suggested above. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the solution of the present invention.

Claims

1. A back contact battery, characterized in that: include: A substrate having a first surface, a second surface, and a side surface, wherein the first surface and the second surface are arranged opposite to each other, and the side surface is connected to the first surface and the second surface respectively; a doping layer disposed on the second surface; The TCO layer includes a main body portion and a micro leakage channel portion, wherein the main body portion is arranged on the side of the doping layer facing away from the substrate, and the micro leakage channel portion extends from at least a portion of the edge of the main body portion along a first direction to the outside of the side surface, and the first direction is the direction from the second surface toward the first surface.

2. The back contact battery according to claim 1, characterized in that The thickness of the micro leakage channel portion decreases gradually along the first direction.

3. The back contact battery according to claim 2, characterized in that The micro leakage channel portion has a first end and a second end at both ends of the first direction, and the second end is provided at one end of the micro leakage channel portion away from the main body portion, wherein the thickness of the first end is H, and the thickness h of the second end is 0<h≤10%H.

4. The back contact battery according to claim 3, characterized in that H is 70nm~90nm.

5. The back contact battery according to claim 1, characterized in that A functional layer is further provided on the first surface, and the micro leakage channel portion extends outside the sidewall of the functional layer.

6. The back contact battery according to claim 5, characterized in that The functional layer includes one or more of a passivation layer and an anti-reflection layer.

7. The back contact battery according to claim 5, characterized in that The length of the micro leakage channel portion along the first direction is L, wherein, 0.1×S≤L≤0.85×S, Wherein, S is the relative distance in the first direction between the side of the functional layer facing away from the first surface and the end of the micro leakage channel portion away from the first surface.

8. The back contact battery according to claim 1, characterized in that The main body includes a transverse portion, a surface of the transverse portion and a surface of the second surface are parallel to each other, and a thickness of the transverse portion is greater than or equal to a thickness of an end of the micro leakage channel portion away from the first surface.

9. The back contact battery according to claim 1, characterized in that The side surface includes a first side surface, a second side surface, a third side surface and a fourth side surface connected in sequence, the first side surface and the third side surface are arranged along a second direction, the second side surface and the fourth side surface are arranged along a third direction, the second direction and the third direction are arranged to intersect, and the micro leakage channel portion is arranged on the outside of at least one of the first side surface, the second side surface, the third side surface and the fourth side surface.

10. The back contact battery according to claim 9, characterized in that The second surface has a plurality of first areas and second areas alternately arranged along the second direction. The main body includes a first TCO segment provided in the first area and a second TCO segment provided in the second area. The first TCO segment and the second TCO segment extend along the third direction. The doped layer includes a first doped layer and a second doped layer with opposite polarities. At least a portion of the first TCO segment is conductively connected to the first doped layer, and at least a portion of the second TCO segment is conductively connected to the second doped layer.

11. The back contact battery according to claim 10, characterized in that The two end regions of the main body in the second direction are denoted as a first edge region and a second edge region, and the portions of the main body located in the first edge region and above the first edge region are independently denoted as the first TCO segment or the second TCO segment, respectively. The first edge region is located at one end of the main body close to the first side surface; The micro leakage channel portion includes a first unit provided on the first side surface, the first unit being connected to the same first TCO segment or the same second TCO segment of the main body located in the first edge region; and / or, The micro leakage channel portion includes a third unit provided on the third side surface, and the third unit is connected to the same first TCO segment or the same second TCO segment of the main body located in the second edge region.

12. The back contact battery according to claim 10, characterized in that The micro leakage channel portion includes a second unit provided on the second side surface, the second unit including a second unit A connected to the first TCO segment and / or a second unit B connected to the second TCO segment; and / or, The micro leakage channel portion includes a fourth unit provided on the fourth side surface, and the fourth unit includes a fourth unit A connected to the first TCO segment and / or a fourth unit B connected to the fourth TCO segment.

13. The back contact battery according to claim 10, characterized in that The first doped layer is provided in the first region, and the second doped layer includes a first segment provided in the first region and a second segment extending to the second region. The first segment is arranged on the side of the first doped layer facing away from the substrate, and an insulating protective layer is provided between the first doped layer and the second doped layer. A channel is opened between the first segment and the insulating protective layer. The first TCO segment includes a contact portion arranged in the channel, the contact portion is in contact with the first doped layer, and the second segment is in contact with the second TCO segment.

14. The back contact battery according to claim 10, characterized in that A first passivation layer is provided between the first doping layer and the substrate, and / or, A second passivation layer is provided on the side of the second doping layer facing the substrate. The second passivation layer includes a first portion provided in the first region and a second portion extending to the second region. The first portion is provided between the insulating protection layer and the second doping layer.

15. A battery assembly, characterized in that: Comprising a back contact cell according to any one of claims 1 to 14.

16. A photovoltaic system, characterized in that: Comprising the battery assembly according to claim 15.

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