Back-contact solar cell, battery arrangement and photovoltaic system

Abstract

Back-contact solar cell, comprehensive: a silicon wafer, wherein the silicon wafer has a front and a back side facing each other, wherein several spaced-apart grooves are formed in the back side, such that the back side comprises several first regions and second regions arranged alternately one after the other, and wherein the first regions and the second regions that are adjacent to each other are spaced apart from each other by the grooves; wherein, in one arrangement direction of the first regions and the second regions, the silicon wafer is provided at the first regions and the edges of the grooves with extension sections that project and protrude towards the top of the grooves; first tunnel layers, wherein the first tunnel layers are applied in a stacked manner to the first areas; doping layers of first polarity, wherein the doping layers of first polarity are arranged in a stacked manner on the first tunnel layers and the extension sections; second tunnel layers, wherein the second tunnel layers are arranged in a stacked manner on the second areas; Doping layers of second polarity, wherein the doping layers of second polarity are arranged on the second tunnel layers in a stacked manner and have a predetermined distance to the edges of the grooves; and a passivation film layer, wherein the passivation film layer covers the first polarity doping layers, the second polarity doping layers and the grooves.

Description

Priority information

[0001] The present application claims the priority and rights of patent applications 202311238215.2 and 202322596534.2, which were filed with the State Intellectual Property Office of China on September 22, 2023, and whose entire contents are incorporated herein by reference. Technical field

[0002] The present application relates to the technical field of solar cells and in particular to a back-contact solar cell, a battery arrangement and a photovoltaic system. background

[0003] A back-contact solar cell is a battery in which both an emitter and a base contact electrode are located on a back side (a non-light-receiving surface) of the battery, and a light-receiving surface of the battery is not shielded by a metal electrode, effectively increasing the short-circuit current of the battery.

[0004] In the current state of the art, a passivation contact area to solve the problem of surface passivation of a groove region on the back side of a back-contact battery and to reduce hydrogen-related defects in a body region requires a defective state of a hydrogen passivation tunnel layer. This necessitates the use of a high-refractive-index passivation film (e.g., high-refractive-index SiNx) to achieve a better mobile hydrogen content, and if excessive hydrogen enters a substrate region, the battery can weaken. Simultaneously, a passivation layer (e.g., AlOx) in the groove region tends to field passivate negative charges, which leads to a p + A layer is induced on the surface, creating a space charge region at the contact of the p +-layer and an n++ layer, and when the area is recombined, compound current is increased in a transition region of the battery, so that the battery's performance is significantly reduced. Summary

[0005] The present application relates to a back-contact solar cell, a battery arrangement and a photovoltaic system.

[0006] The present application is implemented such that the back-contact solar cell in one embodiment of the present application comprises: a silicon wafer, wherein the silicon wafer has a front and a back facing each other, wherein several spaced-apart grooves are formed in the back, such that the back comprises several first regions and second regions arranged alternately, and wherein the first regions and the second regions that are adjacent to each other are spaced apart from each other by the grooves; wherein, in one arrangement direction of the first regions and the second regions, the silicon wafer is provided at the first regions and the edges of the grooves with extension sections that project and protrude towards the top of the grooves; first tunnel layers, wherein the first tunnel layers are applied in a stacked manner to the first areas; doping layers of first polarity, wherein the doping layers of first polarity are arranged in a stacked manner on the first tunnel layers and the extension sections; second tunnel layers, wherein the second tunnel layers are arranged in a stacked manner on the second areas; Doping layers of second polarity, wherein the doping layers of second polarity are arranged on the second tunnel layers in a stacked manner and have a predetermined distance to the edges of the grooves; and a passivation film layer, wherein the passivation film layer covers the first polarity doping layers, the second polarity doping layers and the grooves.

[0007] In some embodiments, the length of the extension section in the arrangement direction of the first areas and the second areas ranges from 0.2 µm to 50 µm.

[0008] In some embodiments, the length of the extension section in the arrangement direction of the first areas and the second areas is from 1 µm to 15 µm.

[0009] In some embodiments, the size of the specified distance ranges from 0.1 µm to 50 µm.

[0010] In some embodiments, the size of the specified distance ranges from 1 µm to 20 µm.

[0011] In some embodiments, the surface of the second area is flush with the surface of the first area.

[0012] In some embodiments, the distance between the surface of the second region and the bottom of the groove is smaller than the distance between the surface of the first region and the bottom of the groove.

[0013] In some embodiments, one side surface of the groove is an inclined surface.

[0014] In some embodiments, in the arrangement direction of the first regions and the second regions, the doping layer of first polarity is provided with a protruding section that extends from the extension section and is located above the groove.

[0015] In some embodiments, the length of the protruding section in the arrangement direction of the first regions and the second regions is from 0.1 µm to 50 µm.

[0016] In some embodiments, the bottom surface and the side surface of the groove, as well as the surface of the extension section facing the groove, each have a concave-convex texture structure.

[0017] In some embodiments, the roughness of the bottom surface of the groove is greater than the roughness of the side surface of the groove, and the roughness of the side surface of the groove is greater than the roughness of the surface of the extension section facing the groove.

[0018] In some embodiments, the surface of the silicon wafer between the second polarity doping layer and the edge of the groove is a polished surface, and the roughness of the surface of the extension section facing the groove is greater than the roughness of the surface of the silicon wafer between the second polarity doping layer and the edge of the groove.

[0019] In some embodiments, the width of the groove ranges from 2 µm to 200 µm.

[0020] In some embodiments, the groove depth ranges from 0.2 µm to 10 µm.

[0021] The present application further provides for a battery arrangement comprising the back-contact solar cell according to one of the foregoing embodiments.

[0022] The present application also provides for a photovoltaic system that includes the aforementioned battery arrangement.

[0023] In the back-contact solar cell, the battery arrangement and the photovoltaic system of the embodiments of the present application, several spaced-apart grooves are formed in the back side of the silicon wafer to divide the back side of the silicon wafer into several first areas and second areas arranged alternately one after the other, wherein in the arrangement direction of the first areas and the second areas the silicon wafer is provided at the first areas and the edges of the grooves with extension sections that project and protrude towards the top of the grooves, and the doping layers of second polarity are arranged on the second tunnel layers in a stacked manner and have the predetermined distance to the edges of the grooves.In this way, on the one hand, since the silicon wafer is provided with extension sections that protrude and stand out towards the top of the grooves, the silicon wafer can form recessed areas with small openings and large outer surfaces, so that the exchange between plasma and the external environment during a deposition process of passivation films can be reduced and a localized distribution of mobile hydrogen content of the passivation film layer can be realized, accordingly the mobile hydrogen content of the passivation film layer is lower in the grooves and the mobile hydrogen content of the passivation film layer is higher in the other areas, thereby achieving optimal passivation and anti-damping effects.On the other hand, since the doping layers of second polarity have the predetermined distance to the surfaces of the grooves, formed platform areas can increase the mobile hydrogen content of the passivation film layer in an upper local area of ​​a space charge region, thereby improving hydrogen passivation in this region, reducing the recombination of the space charge region and improving the performance of the battery.

[0024] Further aspects and advantages of the present application are partly specified in the following description, partly become apparent from the following description, or can be derived from the practice of the present application. Brief description of the drawings Fig. Figure 1 is a schematic diagram of modules of a photovoltaic system provided in an embodiment of the present application; Fig. Figure 2 is a schematic diagram of modules of a battery arrangement provided in an embodiment of the present application; Fig. Figure 3 is a schematic diagram of a cross-section of a back-contact solar cell provided in an embodiment of the present application; Fig. Figure 4 is a schematic diagram of another cross-section of a back-contact solar cell provided in an embodiment of the present application; Fig. Figure 5 is a schematic diagram of yet another cross-section of a back-contact solar cell provided in an embodiment of the present application; and Fig. Figure 6 is a schematic diagram of yet another cross-section of a back-contact solar cell provided in an embodiment of the present application. Description of the symbols of the main elements:

[0025] Photovoltaic system 1000, battery assembly 200, back-contact solar cell 100, silicon wafer 10, front 11, back 12, groove 121, side surface 122, first area 122, second area 123, extension section 13, first tunnel layer 20, doping layer 30 of first polarity, protruding section 31, second tunnel layer 40, doping layer 50 of second polarity, passivation film layer 60, first electrode 70 and second electrode 80. Detailed description of the embodiments

[0026] To clarify the objectives, technical solutions, and advantages of the present application, the present application is described in more detail below with reference to the drawings and embodiments. Examples of the embodiments are shown in the drawings, where identical or similar reference numerals consistently denote identical or similar elements or elements with identical or similar functions. The embodiments described below with reference to the drawings are exemplary and serve only to illustrate the present application; they cannot be interpreted as limiting the present application. Furthermore, it should be noted that the specific embodiments described herein serve only to illustrate the present application and are not intended to limit it.

[0027] In the description of the present application, it should be noted that the orientation or position relationships indicated by the terms "thickness", "width", "top", "bottom", "side", "longitudinal" and the like are orientation or position relationships based on the drawings and serve only to facilitate the description of the present application and to simplify the description, but do not mean or imply that the devices or elements mentioned must have certain orientations or be designed and operated in certain orientations, and therefore cannot be interpreted as restrictions of the present application.

[0028] Furthermore, the terms “first” and “second” are used for descriptive purposes only and cannot be understood as indicating or implying a relative meaning or implicitly specifying the number of technical features listed. Thus, features defined as “first” and “second” may explicitly or implicitly include one or more of the features. In the description of this application, “a plurality of” means two or more unless expressly defined otherwise.

[0029] In the description of this application, it should be noted that, unless expressly stated otherwise and limited, the terms "attached," "connected," and "connection" are to be understood in a broad sense. For example, the connection may be a permanent connection, but also a detachable connection or an integral connection; it may be a mechanical connection, but also an electrical connection or mutual communication; and it may be a direct connection, an indirect connection via an intermediate medium, or also internal communication between two elements or an interaction between the two elements. For those skilled in the art, the specific meanings of the above-mentioned terms in this application can be understood according to the specific situations.

[0030] In the present application, unless otherwise specified and limited, a first feature that is "on" or "below" a second feature may include direct contact between the first feature and the second feature, and may also include the first feature and the second feature not being in direct contact, but being in contact via another intervening feature. Furthermore, a first feature that is "on top," "above," and "above" the second feature may include the first feature being directly above and obliquely above the second feature, or may simply indicate that a horizontal height of the first feature is higher than that of the second feature.The fact that the first feature is located "under", "below", and "below" the second feature implies that the first feature is located directly below and diagonally below the second feature, or simply indicates that the horizontal height of the first feature is less than that of the second feature.

[0031] The following disclosure provides many different embodiments or examples of the implementation of various structures of the present application. To simplify the disclosure of the present application, components and settings of specific examples are described below. These are, of course, merely examples and are not intended to limit the present application. Furthermore, the present application may repeat reference numbers and / or reference letters in different examples, such repetition serving the purpose of simplicity and clarity and not indicating any relationship between different embodiments and / or settings. In addition, the present application contains examples of various specific processes and materials, but those skilled in the art may be aware of applications of other processes and / or use scenarios for other materials.

[0032] Since a silicon wafer is provided with extension sections that project towards the top of the grooves, in the present application the silicon wafer can form recessed areas with small openings and large outer surfaces, so that the exchange between plasma and the external environment during a deposition process of the passivation film layer can be reduced and a localized distribution of a mobile hydrogen content of the passivation film layer can be realized, accordingly the mobile hydrogen content of the passivation film layer is lower in the grooves and the mobile hydrogen content of the passivation film layer is higher in the other areas, thereby achieving optimal passivation and anti-damping effects.On the other hand, since doping layers of second polarity have a predetermined distance from the edges of the grooves, formed platform areas can increase the mobile hydrogen content of the passivation film layer in an upper local area of ​​a space charge region, thereby improving hydrogen passivation in this region, reducing the recombination of the space charge region, and improving the performance of a battery. Design 1

[0033] With reference to Fig. 1 and Fig. 2. A photovoltaic system 1000 in the embodiment of the present application may comprise a battery arrangement 200 in the embodiment of the present application, and the battery arrangement 200 in the embodiment of the present application may comprise a plurality of back-contact solar cells 100 in the embodiment of the present application.

[0034] In some embodiments, the plurality of back-contact solar cells 100 in the battery arrangement 200 can be sequentially connected in series to form a battery string, and the battery strings can be connected in series, parallel or in a series-parallel combination manner to realize a pooling of the current output, for example, the connection between the battery cells can be realized by soldering a solder strip and the connection between the battery strings can be realized by a busbar.

[0035] With reference to Fig. 3 The back-contact solar cell 100 in the embodiment of the present application can comprise a silicon wafer 10, first tunnel layers 20, doping layers 30 of first polarity, second tunnel layers 40, doping layers 50 of second polarity and a passivation film layer 60.

[0036] The silicon wafer 10 has a front face 11 and a back face 12, which are opposite each other. Several spaced grooves 121 are formed in the back face 12, such that the back face 12 comprises several first regions 122 and second regions 123, which are arranged alternately one after the other. The first regions 122 and the second regions 123 that are adjacent to each other are spaced apart by the grooves 121. For example, the first regions 122 and the second regions 123 can be arranged alternately in a lateral direction of the back-contact solar cell 100, and the grooves 121 extend in a longitudinal direction to space apart the first regions 122 and the second regions 123 that are adjacent to each other.

[0037] As in Fig. Figure 3 shows that in an arrangement direction of the first areas 122 and the second areas 123 of the silicon wafer 10, extension sections 13 are provided at the first areas 122 and the edges of the grooves 121, which project and protrude towards the top of the grooves 121.

[0038] The first tunnel layers 20 are applied in a stacked manner to the first areas 122, and the doping layers 30 of the first polarity are arranged in a stacked manner on the first tunnel layers 20 and the extension sections 13. The second tunnel layers 40 are arranged in a stacked manner on the second areas 123, and the doping layers 50 of the second polarity are arranged in a stacked manner on the second tunnel layers 40 and have a predetermined distance L to the edges of the grooves 121.

[0039] The passivation film layer 60 can cover the back side 12 of the entire silicon wafer 10, i.e. the passivation film layer 60 can cover the doping layers 30 of first polarity, the doping layers 50 of second polarity and the grooves 121.

[0040] In the back-contact solar cell 100, the battery arrangement 200, and the photovoltaic system 1000 in the embodiment of the present application, several spaced-apart grooves 121 are formed in the back side 12 of the silicon wafer 10 to subdivide the back side 12 of the silicon wafer 10 into several first regions 122 and second regions 123, which are arranged alternately one after the other. In the arrangement direction of the first regions 122 and the second regions 123, the silicon wafer 10 is provided at the first regions 122 and the edges of the grooves 121 with extension sections 13 that project and protrude towards the top of the grooves 121, and the doping layers 50 of the second polarity are arranged on the second tunnel layers 40 in a stacked manner and have the predetermined distance L to the edges of the grooves 121.In this way, on the one hand, since the silicon wafer 10 is provided with the extension sections 13 that extend towards and project from the top of the grooves, the silicon wafer 10 can form recessed areas with small openings and large outer surfaces, thus reducing the exchange between plasma and the external environment during a deposition process of the passivation film layer 60 (e.g., SiNx film layers), and achieving a localized distribution of the mobile hydrogen content of the passivation film layer. Accordingly, the mobile hydrogen content of the passivation film layer 60 is lower in the grooves 121 and higher in the remaining areas, thereby achieving optimal passivation and anti-damping effects. On the other hand, since the doping layers 50 of the second polarity have the predetermined distance L to the edges of the grooves 121 (i.e.,, there are platform areas between the doping layers 50 of second polarity and the grooves 121), the platform areas formed can increase the mobile hydrogen content of the passivation film layer 60 in an upper local area of ​​a space charge region, thereby improving hydrogen passivation in this region, reducing the recombination of the space charge region and improving the performance of the battery.

[0041] In particular, in the embodiment of the present application, the front side 11 is a surface that receives light during operation of the back-contact solar cell 100, and the rear side 12 is a back-illumination side during operation of the back-contact solar cell 100. The silicon wafer 10 can be a monocrystalline silicon wafer 10 or a polycrystalline silicon wafer 10 and can be a P-type silicon wafer 10 or an N-type silicon wafer 10, which is not specifically limited herein. The grooves 121 on the silicon wafer 10 and the extension sections 13 of the silicon wafer 10 can be formed by a combination of grooving and etching; for example, small openings can first be formed on the silicon wafer 10, and then the openings can be etched by acidic or alkaline etching to create recessed areas (i.e.,to form the grooves 121) with small openings and large interior areas, and then the extension sections 13 are formed, which extend to the top of the grooves 121 and protrude, thereby reducing the exchange between the plasma and the external environment during the deposition process of the passivation film layer 60.

[0042] It can be understood that “where the specified distance L between the doping layer 50 of the second polarity and the groove 121 is present” means that the specified distance L between the edge of the doping layer 50 of the second polarity, which is close to the groove 121, and the edge of the groove 121 in the arrangement direction of the first areas 122 and the second areas 123 is present.

[0043] In the embodiment of the present application, the first-polarity doping layer 30 can be either a P-type or an N-type doping layer, and the second-polarity doping layer 50 can be either a P-type or an N-type doping layer. For example, in some embodiments, the first-polarity doping layer 30 can be a P-type doping layer, the second-polarity doping layer 50 can be an N-type doping layer, and both the first tunnel layer 20 and the second tunnel layer 40 can be one or a combination of several of a tunnel oxide layer (e.g., a tunnel silicon oxide layer), an intrinsic silicon carbide layer, and an intrinsic amorphous silicon layer, which is not specifically limited herein.

[0044] In particular, the passivation film layer 60 may preferably comprise an aluminum oxide layer and a silicon nitride layer arranged in a stacked manner, and may of course also comprise one or a combination of several of a silicon oxynitride layer, an intrinsic silicon carbide layer, an intrinsic amorphous silicon layer and a silicon oxide layer, which is not specifically limited herein.

[0045] Furthermore, the back-contact solar cell 100 is further provided with first electrodes 70 and second electrodes 80, wherein the first electrodes 70 can be arranged in the first regions 122 and can penetrate the passivation film layer 60 to be in ohmic contact with the doping layers 30 of first polarity, wherein the second electrodes 80 can be arranged in the second regions 123 and can penetrate the passivation film layer 60 to be in ohmic contact with the doping layers 50 of second polarity, and both the first electrodes 70 and the second electrodes 80 can be metal electrodes.

[0046] In the embodiment of the present application, the back surface 12 of the silicon wafer 10 can be a polished surface or a textured surface, and the textured surface can, for example, be a surface with relatively high roughness, such as suede. In some embodiments, the area in the second region 123 covered by the second-polarity doping layer 50 can be a polished surface, and the area in the second region 123 not covered by the second-polarity doping layer 50 can be a textured surface, whereby, of course, the area in the second region 123 not covered by the second-polarity doping layer 50 can also be a polished surface, i.e., the surface of the silicon wafer between the second-polarity doping layer 50 and the edge of the groove 121 is a polished surface.

[0047] It can be understood that in the embodiment of the present application, the battery arrangement 200 may further comprise a metal frame, a backplate, photovoltaic glass, and an adhesive film (not shown in the figures). The adhesive film may be inserted as a filler between the front face 11 of the back-contact solar cell 100 and the photovoltaic glass, the rear face 12, the backplate, adjacent battery cells, and the like. The adhesive film may, for example, be a transparent colloid with good light transmission and aging resistance; for example, the adhesive film may be an EVA adhesive film or a POE adhesive film, which may be specifically selected according to the actual circumstances and is not limited therein.

[0048] The photovoltaic glass can be applied to the adhesive film on the front 11 of the back-contact solar cell 100. This photovoltaic glass can be ultra-white glass, which exhibits high light transmittance and transparency and possesses excellent physical, mechanical, and optical properties. For example, the ultra-white glass has a light transmittance of more than 92% and can thus protect the back-contact solar cell 100 as much as possible without impairing its efficiency. Simultaneously, the adhesive film can bond the photovoltaic glass and the back-contact solar cell 100 together. This provides the back-contact solar cell 100 with a seal and insulation due to the presence of the adhesive film, as well as protection against water and moisture.

[0049] The backplate can be attached to the adhesive film on the back 12 of the back-contact solar cell 100, the backplate can protect and support the back-contact solar cell 100 and exhibits reliable insulating ability, water resistance and aging resistance, the backplate can be made of a variety of materials, which can generally be tempered glass, organic glass, an aluminum alloy, TPT composite adhesive film and the like, and the backplate can be specially specified according to the specific conditions, which are not limited herein.An assembly consisting of the backplate, the back-contact solar cell 100, the adhesive film and the photovoltaic glass can be arranged on the metal frame, the metal frame serving as a main external support structure of the entire battery assembly 200 and being able to stably support and secure the battery assembly 200, for example, the battery assembly 200 can be attached by the metal frame to a position where the battery assembly 200 needs to be attached.

[0050] In some embodiments, the Photovoltaic System 1000, as presented, can be applied to a photovoltaic power plant, such as a ground-mounted power plant, a rooftop power plant, a surface water power plant, or the like, and can also be applied to a device or apparatus for generating electricity using solar energy, for example, a solar power supply for users, a solar street lamp, a solar vehicle, a solar building, or the like. It should be understood, of course, that the application scenario of the Photovoltaic System 1000 is not limited to this; that is, the Photovoltaic System 1000 can be used in all areas where solar energy is to be used for electricity generation.Using the example of a photovoltaic power generation system network, the photovoltaic system 1000 can comprise a photovoltaic array, a combination box, and an inverter, wherein the photovoltaic array can be an arrangement combination of a plurality of battery arrangements 200, for example, the plurality of battery arrangements 200 can form a plurality of photovoltaic arrays, wherein the photovoltaic array is connected to the combination box, the combination box can aggregate the current generated by the photovoltaic array, and the aggregated current flows through the inverter to be converted into the alternating current required by the power grid, and is then connected to a power supply network to realize the solar power supply. Design 2

[0051] In some embodiments, the length of the extension section 13 in the arrangement direction of the first areas 122 and the second areas 123 can be from 0.2 µm to 50 µm.

[0052] In this way, by setting the length of the extension section 13 within this appropriate range, it can be prevented that the length of the extension section 13 is too short to effectively fulfill the function of reducing the exchange between plasma and the external environment during the deposition process of the passivation film layer, and it can also be prevented that the length of the extension section 13 is too long, leading to an opening in the groove 121 that is too small and causing major difficulties in the etching process, and at the same time it can also be prevented that the length of the extension section 13 is too long, leading to breakage.

[0053] In particular, in such an embodiment the length of the extension section 13 can be, for example, 0.2 µm, 0.4 µm, 0.6 µm, 0.8 µm, 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 20 µm, 30 µm, 40 µm, 50 µm or any value between 0.2 µm and 50 µm.

[0054] In some embodiments, according to research and verification by the inventors of the present application, it was discovered that, in order to better prevent breakage of the extension section 13 and to ensure the function of reducing the exchange between the plasma and the external environment during the deposition process of the passivation film layer, the length of the extension section 13 in the present application is preferably from 1 µm to 15 µm. embodiment 3

[0055] With reference to Fig. 3 In some embodiments, the size of the specified distance L can range from 0.1 µm to 50 µm.

[0056] In this way, by setting the distance between the second polarity doping layer 50 and the groove 121 within the above-mentioned appropriate range, it can be ensured that the platform area between the second polarity doping layer 50 and the edge of the groove 121 has an appropriate size, so that the mobile hydrogen content of a local passivation film layer on the platform area can be effectively increased, thereby improving the hydrogen passivation of the local area, reducing the recombination of the space charge area, and preventing the overall efficiency of the battery from being impaired by an insufficient charge carrier collection efficiency because the area of ​​the second area 123 without the second polarity doping layer 50 is too large due to the excessively large predetermined distance L.

[0057] In particular, in the present application, the size of the specified distance L can be, for example, 0.1 µm, 0.2 µm, 0.3 µm, 0.4 µm, 0.5 µm, 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 20 µm, 30 µm, 40 µm, 50 µm or any value between 0.1 µm and 50 µm.

[0058] In some embodiments, the research and verifications of the inventors of the present application have revealed that, in the embodiment of the present application, the size of the specified distance L can preferably be from 1 µm to 20 µm. In this way, the overall efficiency of the battery can be ensured while reducing the recombination of the space charge area. Design 4

[0059] With reference to Fig. In some embodiments, the surface of the second region 123 is flush with the surface of the first region 122.

[0060] In this way, the first area 122 and the second area 123 can be formed directly using the silicon wafer 10 without having to perform other processes such as etching. Design 5

[0061] With reference to Fig. 4 In some embodiments, the distance between the surface of the second region 123 and the bottom of the groove 121 is smaller than the distance between the surface of the first region 122 and the bottom of the groove 121, i.e., the surface of the second region 123 sinks into the silicon wafer 10.

[0062] In this way, if the doping layer of the second polarity is an N-type doping layer, when the battery is transported during a manufacturing process, the surface can contact components such as a belt and a roller, which can lead to scratches on the surface. The etching rate of an alkaline solution is higher on an N-type surface than on a P-type surface, so the N-type surface is more likely to be etched away in the alkaline solution due to the scratches, leading to failure. Therefore, by recessing the N-type surface, scratches on the N-type surface during battery transport can be avoided, thus reducing the risk of failure. Design 6

[0063] With reference to Fig. 5 in some embodiments is a side surface 122 of the groove 121 (i.e. the bottom surface of the groove 121 is connected to the surface of the first region 122 and the surface of the second region 123) an inclined surface.

[0064] In this way, since a vertical crystal plane has more defects, the formation of the inclined side surface 122 can reduce surface defect states of the groove 121, and the formation of the inclined surface can reduce surface recombination and improve the performance of the battery. Model 7

[0065] With reference to Fig. In some embodiments, in the arrangement direction of the first areas 122 and the second areas 123, the doping layer 30 is provided with a projecting section 31 which protrudes from the extension section 13 and is located above the groove 121.

[0066] In this way, since the doping layer 30 of first polarity is provided with the protruding section 31, which projects to the top of the groove 121, a local second doping layer can be selectively in contact with the protruding section 31 during the application of the doping layer 50 of second polarity, thereby improving a subsequent electrical injection effect and thus improving the subsequent repair efficiency and the repair effect of the back-contact solar cell 100.

[0067] In some embodiments, the length of the protruding section 31 in the arrangement direction of the first regions 122 and the second regions 123 can range from 0.1 µm to 50 µm. This avoids the phenomenon of breakage caused by an excessively long protruding section 31.

[0068] In particular, in the present application, the length of the preceding section 31 may be, for example, 0.1 µm, 0.2 µm, 0.3 µm, 0.4 µm, 0.5 µm, 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 20 µm, 30 µm, 40 µm, 50 µm, or any value between 0, 1 µm, and 50 µm, which is not specifically limited herein. Preferably, the length of the preceding section 31 may be from 1 µm to 20 µm. Design 8

[0069] In some embodiments, the bottom surface and the side surface 1211 of the groove 121 and the surface of the extension section 13 facing the groove each have a concave-convex texture structure.

[0070] In this way, by forming the concave-convex texture structures on the three surfaces, the reflection of the light entering the silicon wafer 10 can be increased, thereby increasing the number of rays absorbed by the battery and improving the conversion efficiency of the battery.

[0071] In some embodiments, the roughness of the bottom surface of the groove 121 is greater than the roughness of the side surface 1211 of the groove 121, and the roughness of the side surface 1211 of the groove 121 is greater than the roughness of the surface of the extension section 13 facing the groove. In this way, by defining different texture structures with different roughness values, the wettability of local areas can be improved and the cleaning effect during cleaning of the battery cells can be enhanced.

[0072] Furthermore, in some embodiments, the surface of the silicon wafer (i.e., the surface of the platform area) between the second polarity doping layer 50 and the edge of the groove 121 is a polished surface, and the roughness of the surface of the extension section 13 facing the groove 121 is greater than the roughness of the surface of the silicon wafer between the second polarity doping layer 50 and the edge of the groove 121. Design 9

[0073] In some embodiments, the width of the groove 121 ranges from 2 µm to 200 µm.

[0074] In this way, by setting the width of the groove 121 within this appropriate range, it is possible, on the one hand, to avoid that the width of the groove 121 is too small to fulfill the function of isolating the doping layer 30 of the first polarity from the doping layer 50 of the second polarity, and on the other hand, to prevent the area of ​​an invalid region of the back-contact solar cell 100 from being too large due to an excessive width of the groove 121.

[0075] In particular, in such an embodiment the width of the groove 121 can be 2 µm, 4 µm, 6 µm, 8 µm, 10 µm, 20 µm, 40 µm, 60 µm, 80 µm, 100 µm, 120 µm, 140 µm, 160 µm, 180 µm, 200 µm or any value between 2 µm and 200 µm, which is not specifically limited herein. Design 10

[0076] In some embodiments, the depth of the groove 121 can range from 0.2 µm to 10 µm.

[0077] In this way, by setting the depth of groove 121 within this appropriate range, it is possible to avoid the groove 121 failing to achieve an effective insulation effect due to insufficient depth, and it is also possible to avoid a significant reduction in the strength of the silicon wafer 10 at the groove 121 due to excessive depth, and to reduce the risk of breakage during the manufacturing process of the back-contact solar cell 100. That is, if the depth of groove 121 is too great, the position where the groove 121 is located will be thinner, so that the strength of the back-contact solar cell 100 at the groove 121 will be too low to be prone to breakage.

[0078] In particular, in such an embodiment the depth of the groove 121 can be 0.2 µm, 0.4 µm, 0.6 µm, 0.8 µm, 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm or any value between 0.2 µm and 10 µm, which is not specifically limited herein.

[0079] In the description of this specification, terms such as "some embodiments," "an exemplary embodiment," "an example," "a specific example," or "some examples," and the like, mean that certain features, structures, materials, or properties described in combination with the embodiment or example are included in at least one embodiment or example of this application. In this description, the schematic representation of the aforementioned terms does not necessarily refer to the same embodiment or example. Furthermore, the described specific features, structures, materials, or properties may be combined in a suitable manner in one or more embodiments or examples.

[0080] Furthermore, the foregoing descriptions are merely preferred embodiments of the present application and are not intended to restrict the present application, and all modifications, equivalent replacements, improvements and the like made in the sense and within the framework of the principles of the present application shall fall within the scope of protection of the present application. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 202311238215.2

[0001] WO 202322596534.2

[0001]

Claims

[1] Back-contact solar cell comprising: a silicon wafer, wherein the silicon wafer has a front and a back side facing each other, wherein several spaced-apart grooves are formed in the back side, such that the back side comprises several first regions and second regions arranged alternately one after the other, and wherein the first regions and the second regions that are adjacent to each other are spaced apart from each other by the grooves; wherein, in one arrangement direction of the first regions and the second regions, the silicon wafer is provided at the first regions and the edges of the grooves with extension sections that project and protrude towards the top of the grooves; first tunnel layers, wherein the first tunnel layers are applied in a stacked manner to the first areas; doping layers of first polarity, wherein the doping layers of first polarity are arranged in a stacked manner on the first tunnel layers and the extension sections; second tunnel layers, wherein the second tunnel layers are arranged in a stacked manner on the second areas; Doping layers of second polarity, wherein the doping layers of second polarity are arranged on the second tunnel layers in a stacked manner and have a predetermined distance to the edges of the grooves; and a passivation film layer, wherein the passivation film layer covers the first polarity doping layers, the second polarity doping layers and the grooves. [2] Back-contact solar cell according to claim 1, wherein in the arrangement direction of the first areas and the second areas the length of the extension section is from 0.2 µm to 50 µm. [3] Back-contact solar cell according to claim 2, wherein in the arrangement direction of the first areas and the second areas the length of the extension section is from 1 µm to 15 µm. [4] Back-contact solar cell according to claim 1, wherein the size of the predetermined distance is from 0.1 µm to 50 µm. [5] Back-contact solar cell according to claim 4, wherein the size of the predetermined distance is from 1 µm to 20 µm. [6] Back-contact solar cell according to claim 1, wherein a surface of the second region is flush with a surface of the first region. [7] Back-contact solar cell according to claim 1, wherein a distance between the surface of the second region and a bottom of the groove is smaller than a distance between the surface of the first region and a bottom of the groove. [8] Back-contact solar cell according to claim 1, wherein one side surface of the groove is an inclined surface. [9] Back-contact solar cell according to claim 1, wherein in the arrangement direction of the first regions and the second regions the doping layer of first polarity is provided with a protruding section which protrudes from the extension section and is located above the groove. [10] Back-contact solar cell according to claim 9, wherein in the arrangement direction of the first regions and the second regions the length of the preceding section is from 0.1 µm to 50 µm. [11] Back-contact solar cell according to claim 1, wherein a bottom surface and a side surface of the grooves and a surface of the extension section facing the groove each have a concave-convex texture structure. [12] Back-contact solar cell according to claim 11, wherein the roughness of the bottom surface of the groove is greater than the roughness of the side surface of the groove and the roughness of the side surface of the groove is greater than the roughness of the surface of the extension section facing the groove. [13] Back-contact solar cell according to claim 1, wherein a surface of the silicon wafer between the second polarity doping layer and the edge of the groove is a polished surface and a roughness of a surface of the extension section facing the groove is greater than a roughness of a surface of the silicon wafer between the second polarity doping layer and the edge of the groove. [14] Back-contact solar cell according to claim 1, wherein the groove width is from 2 µm to 200 µm. [15] Back-contact solar cell according to claim 1, wherein the groove depth is from 0.2 µm to 10 µm. [16] Battery arrangement comprising multiple back-contact solar cells according to any one of claims 1-15. [17] Photovoltaic system comprising the battery arrangement according to claim 16.

Images