Back contact solar cell, cell assembly and photovoltaic system

Abstract

The utility model is suitable for the field of photovoltaic technology, and provides a back contact solar cell, a cell assembly and a photovoltaic system, the back surface of a silicon wafer is provided with a plurality of grooves arranged at intervals, the silicon wafer is provided with first extension parts at the edges of the first area and the grooves, and the first extension parts extend and protrude above the grooves. The second polarity doping layer is arranged on the second tunneling layer in a stacked mode, a preset distance is formed between the second polarity doping layer and the edge of the groove, and the second polarity doping layer is provided with a second extending part extending towards the direction of the groove. Therefore, a sunken area with a small opening and a large interior is formed at the groove, so that the exchange between plasma and the outside in the deposition process of the passive film layer can be reduced, and the optimal passivation and anti-attenuation effects are realized. And meanwhile, the second extension part is arranged, so that the passive film layer can cover the underlying structure more uniformly and more comprehensively, and the contact area of the passive film layer and the underlying structure is increased. And the passivation effect is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of photovoltaics, and in particular relates to a back-contact solar cell, a battery assembly and a photovoltaic system. Background Art

[0002] A back-contact solar cell is a cell in which both the emitter and base contact electrodes are placed on the back side (non-light-receiving side) of the cell. The light-receiving side of the cell is not blocked by any metal electrodes, thereby effectively increasing the efficiency of the cell.

[0003] In related technologies, to address the surface passivation problem in the grooved region on the back of back-contacted cells and reduce hydrogen-related defects in the body region, the passivated contact region requires hydrogen to passivate the defect states of the tunneling layer. This requires the use of a high-refractive-index passivation film (e.g., high-refractive-index SiNx) to achieve a higher mobile hydrogen content. Excessive hydrogen entering the substrate region can cause cell degradation. At the same time, the passivation layer in the grooved region (e.g., AlOx) is prone to negative charge field passivation. This configuration induces a surface p+ layer, creating a space charge region at the contact between the p+ layer and the n++ layer. Recombination in this region will increase the junction recombination current of the cell, significantly reducing cell performance. Utility Model Content

[0004] The utility model provides a back-contact solar cell, a battery assembly and a photovoltaic system, aiming to solve the technical problems of large battery attenuation and reduced battery performance of back-contact solar cells in the prior art.

[0005] The utility model is implemented as follows: a back contact solar cell comprising:

[0006] A silicon substrate having a backlight surface and a light-facing surface opposite to each other, first regions and second regions alternately arranged on the backlight surface of the silicon substrate, and a groove is arranged between adjacent first regions and second regions;

[0007] a first tunneling layer, the first tunneling layer being stacked and covering the first region;

[0008] a first polarity doped layer, wherein the first polarity doped layer is stacked on the first tunneling layer, and the first polarity doped layer has a first extending portion extending toward the groove;

[0009] a second tunneling layer, the second tunneling layer being stacked on the second region;

[0010] a second polarity doped layer, the second polarity doped layer being stacked on the second tunneling layer, wherein a side surface of the second polarity doped layer is spaced a first distance from a sidewall of the groove, and a second extension portion extending from a side of the second polarity doped layer away from the silicon substrate toward the groove; and

[0011] A passivation film layer covers the first polarity doped layer, the second polarity doped layer and the groove.

[0012] Optionally, the second extension portion does not extend above the groove.

[0013] Optionally, the passivation film layer surrounds the second extension portion.

[0014] Optionally, the sidewalls of the second tunneling layer are flush with the sidewalls of the connected second polarity doped layer, the passivation film layer covers the silicon substrate, and there is a second gap distance between the passivation film layer covering the bottom surface of the second extension portion and the passivation film layer covering the silicon substrate, and the second gap distance is less than 150nm.

[0015] Optionally, along the arrangement direction of the first region and the second region, the length of the first extending portion is greater than the length of the second extending portion.

[0016] Optionally, along the arrangement direction of the first region and the second region, the length of the first extension portion is 0.5 μm-3 μm.

[0017] Optionally, along the arrangement direction of the first region and the second region, the length of the second extension portion is less than or equal to 200 nm.

[0018] Optionally, the surface of the second region is flush with the surface of the first region.

[0019] Optionally, 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.

[0020] Optionally, the side surface of the groove is a slope.

[0021] Optionally, a surface of the second extension portion facing the groove has a concave-convex structure.

[0022] Optionally, 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 surfaces of the first extension portion and the second extension portion away from the groove.

[0023] Optionally, the width of the groove is 2um-200um.

[0024] Optionally, the recessed depth of the groove is 0.2um-10um.

[0025] The utility model also provides a battery assembly, comprising the above-mentioned back-contact solar cell sheet.

[0026] The utility model also provides a photovoltaic system, comprising the above-mentioned battery assembly.

[0027] The beneficial effect achieved by the present invention is that, due to the provision of a first extension portion extending above the groove, a recessed area with a small opening and a large interior is formed at the groove, which can reduce the exchange of plasma with the outside world during the deposition process of the passivation film layer, and realize the localized distribution of the mobile hydrogen content of the passivation film layer, so as to achieve the best passivation and anti-attenuation effect. At the same time, the provision of a second extension portion allows the passivation film layer to be more evenly and comprehensively covered on the underlying structure, thereby increasing the contact area between the passivation film layer and the underlying structure and improving the passivation effect. The enhanced passivation effect helps to reduce leakage current, which significantly contributes to the long-term performance stability and efficiency improvement of the battery cell. In addition, the provision of the first extension portion and the second extension portion can increase the reflection of incident light entering the silicon substrate and improve battery efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic cross-sectional view of a back-contact solar cell provided in an embodiment of the present application;

[0029] Figure 2 is another schematic cross-sectional structure diagram of a back-contact solar cell provided in an embodiment of the present application;

[0030] Figure 3 is another schematic cross-sectional structure diagram of a back-contact solar cell provided in an embodiment of the present application;

[0031] Figure 4 is another schematic cross-sectional structure diagram of a back-contact solar cell provided in an embodiment of the present application;

[0032] Figure 5 This is a real image view of the back contact solar cell provided in an embodiment of the present application.

[0033] Description of reference numerals:

[0034] 100. Back-contact solar cell; 101. Silicon substrate; 1011. Third extension portion; 110. First region; 120. Second region; 130. Groove; 102. First tunneling layer; 103. First polarity doped layer; 1031. First extension portion; 104. Second tunneling layer; 1041. Second extension portion; 105. Second polarity doped layer; 106. Passivation film layer; 107. First electrode; 108. Second electrode. DETAILED DESCRIPTION

[0035] 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, in which 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.

[0036] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0037] 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 the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of this utility model, "plurality" means two or more, unless otherwise specifically defined.

[0038] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections, or mutual communication; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0039] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0040] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but a person of ordinary skill in the art will appreciate the application of other processes and / or the use of other materials.

[0041] The utility model is provided with a first extension portion extending above the groove, so that a recessed area with a small opening and a large interior is formed at the groove, which can reduce the exchange of plasma with the outside world during the deposition process of the passivation film layer, and realize the localized distribution of the movable hydrogen content of the passivation film layer, so as to achieve the best passivation and anti-attenuation effect. At the same time, a second extension portion is provided, so that the passivation film layer can be more evenly and comprehensively covered on the underlying structure, thereby increasing the contact area between the passivation film layer and the underlying structure and improving the passivation effect. The enhanced passivation effect helps to reduce leakage current, which has a significant contribution to the long-term performance stability and the efficiency improvement of the battery cell. In addition, the provision of the first extension portion and the second extension portion can increase the reflection of the incident light entering the silicon substrate and improve the battery efficiency.

[0042] Example 1

[0043] like Figure 1 and Figure 5 As shown, this embodiment provides a back-contact solar cell 100, comprising:

[0044] A silicon substrate 101 having a backlight surface and a light-facing surface opposite to each other, first regions 110 and second regions 120 alternately arranged on the backlight surface of the silicon substrate 101, and grooves 130 arranged between adjacent first regions 110 and second regions 120;

[0045] A first tunneling layer 102 is stacked and covered on the first region 110;

[0046] A first polarity doped layer 103 , wherein the first polarity doped layer 103 is stacked on the first tunneling layer 102 , and the first polarity doped layer 103 has a first extending portion 1031 extending toward the groove 130 ;

[0047] A second tunneling layer 104 , wherein the second tunneling layer 104 is stacked on the second region 120 ;

[0048] a second polarity doped layer 105, the second polarity doped layer 105 being stacked on the second tunneling layer 104, with a first spacing distance between a side surface of the second polarity doped layer 105 and a side wall of the groove 130, and a second extension portion 1051 extending from a side of the second polarity doped layer 105 away from the silicon substrate 101 toward the groove 130; and

[0049] The passivation film layer 106 covers the first polarity doped layer 103 , the second polarity doped layer 105 and the groove 130 .

[0050] The silicon substrate 101 has two main surfaces, a light-facing surface and a backlight surface. The light-facing surface directly faces the sunlight, while the backlight surface is the other side. The two surfaces are arranged opposite each other.

[0051] Two different regions are arranged on the backlight surface of the silicon substrate 101, namely a first region 110 and a second region 120, and the two regions are arranged alternately. Specifically, a plurality of first regions 110 and a plurality of second regions 120 are arranged alternately along a first direction, and both the first regions 110 and the second regions 120 extend along a second direction, which intersects the first direction. The first regions 110 and the second regions 120 can be arranged alternately along the lateral direction of the silicon substrate 101 and both extend along the longitudinal direction. That is, the first direction can be the lateral direction of the back-contact cell, and the second direction can be the longitudinal direction of the back-contact cell, and the two directions are perpendicular to each other. Of course, in other embodiments, the first direction and the second direction can also be other directions. For example, they can be diagonal directions of the silicon substrate 101, and this is not limited to this.

[0052] A groove 130 is provided between the adjacent first region 110 and the second region 120 . The groove 130 extends along the second direction. The extending direction of the groove 130 is consistent with the extending direction of the first region 110 and the second region 120 . The groove 130 separates the adjacent first region 110 and the second region 120 .

[0053] A first tunneling layer 102 and a first polarity doped layer 103 are sequentially stacked within the first region 110. A first extension 1031 of the first polarity doped layer 103 extends from the first region 110 to above the groove 130, with the projection of the first extension 1031 falling into the groove 130. A second tunneling layer 104 and a second polarity doped layer 105 are sequentially stacked within the second region 120. A predetermined distance L is provided between the second polarity doped layer 105 and the edge of the groove 130, i.e., a terrace region is formed between the second polarity doped layer 50 and the groove 121. This terrace region can increase the mobile hydrogen content of the passivation film layer 60 in the localized region above the space charge region, thereby enhancing hydrogen passivation in this region, reducing recombination in the space charge region, and improving battery performance.

[0054] A second extension portion 1051 extends from the side of the second polarity doped layer 105 away from the silicon substrate 101 toward the groove, and the second extension portion 1051 protrudes from the sidewall of the second polarity doped layer 105. The first polarity doped layer 103 and the second polarity doped layer 105 form regions with different electrical characteristics, supporting the formation of a PN junction and the separation of carriers.

[0055] The passivation film layer 106 may cover the entire backlight surface of the silicon substrate 101 , that is, the passivation film layer 106 may cover the first polarity doped layer 103 , the second polarity doped layer 105 and the groove 130 .

[0056] Due to the presence of the first extension portion 1031, the notch of the groove 130 is blocked, so that a concave area with a small opening and a large interior is formed at the groove 130, which can reduce the exchange of plasma with the outside world during the deposition process of the passivation film layer 106 (for example, the SiNx film layer), and realize the localized distribution of the mobile hydrogen content of the passivation film layer 106 to achieve the best passivation and anti-attenuation effect. The presence of the first extension portion 1031 and the second extension portion 1051 enables the passivation film layer 106 to be more evenly and comprehensively covered on the underlying structure (silicon substrate 101 and the first tunneling layer 102 and the second tunneling layer 104 and the corresponding doping layer placed on the silicon substrate 101), including the first extension portion 1031 and the second extension portion 1051 and the groove 130, thereby increasing the contact area between the passivation film layer 106 and the underlying structure. Improve the passivation effect. The enhanced passivation effect helps to reduce leakage current, which significantly contributes to the long-term performance stability and efficiency improvement of the battery cell. In addition, providing the first extension portion 1031 and the second extension portion 1051 can increase the reflection of incident light entering the silicon substrate 101 and improve the efficiency of the cell.

[0057] Specifically, the silicon substrate 101 can be a single crystal silicon substrate 101 or a polycrystalline silicon substrate 101, and can be a P-type silicon substrate or an N-type silicon substrate, without limitation. The groove 130 on the silicon substrate 101 can be formed by a combination of grooving and etching. For example, a small opening can be first formed on the silicon substrate 101, and then the opening can be etched by acid etching or alkaline etching to form the final groove 130.

[0058] The passivation film layer 106 may preferably include a stacked aluminum oxide layer and a silicon nitride layer. Of course, it may also include one or more combinations 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 here.

[0059] It can be understood that the first polarity doped layer 103 can be one of a P-type doped layer and an N-type doped layer, and the second polarity doped layer 105 can be the other of a P-type doped layer and an N-type doped layer. For example, in some embodiments, the first polarity doped layer 103 can be a P-type doped layer, the second polarity doped layer 105 can be an N-type doped layer, and the first tunneling layer 102 and the second tunneling layer 104 can both be one or more combinations of a tunneling oxide layer (for example, a tunneling silicon oxide layer), an intrinsic silicon carbide layer, and an intrinsic amorphous silicon layer, and there is no specific limitation here.

[0060] In addition, the back-contact solar cell 100 further includes a first electrode 107 and a second electrode 108. The first electrode 107 can be disposed in the first region 110 and penetrate the passivation film layer 106 to form an ohmic contact with the first polarity doped layer 103. The second electrode 108 can be disposed in the second region 120 and penetrate the passivation film layer 106 to form an ohmic contact with the second polarity doped layer 105. Both the first electrode 107 and the second electrode 108 can be metal electrodes.

[0061] Specifically, the back side of the silicon substrate 101 may include a polished surface or a textured surface. The textured surface may be a surface with a relatively high roughness, such as a velvet surface. Furthermore, in some embodiments, the area covered by the second polarity doped layer 105 in the second region 120 may be a polished surface, and the area not covered by the second polarity doped layer 105 in the second region 120 may be a textured surface. Of course, the area not covered by the second polarity doped layer 105 in the second region 120 may also be a polished surface. That is, the silicon wafer surface between the second polarity doped layer 105 and the edge of the groove 130 is a polished surface.

[0062] In some embodiments, as Figure 4As shown, the silicon substrate 101 may also have a third extension portion 1011 extending and protruding above the groove 130 at the edge of the first region 110 and the groove 130, with the projection of the protruding portion falling into the groove 130. The first tunneling layer 102 is stacked and covered on the first region 110 and the third extension portion 1011, and the first polarity doped layer 103 and the first extension portion 1031 are stacked and disposed on the first tunneling layer 102.

[0063] Furthermore, the first extending portion 1031 has a protruding portion extending further upward of the groove 130 than the third extending portion 1011 .

[0064] Example 2

[0065] Based on the first embodiment, the second extending portion 1051 does not extend above the groove 130 .

[0066] This prevents the projection of the second extension 1051 from falling into the groove 130. This maintains the functional independence of the first region 110 and the second region 120, avoids unnecessary interference between differently doped regions, and reduces the electric field shielding effect within the cell. This layout facilitates more efficient carrier transfer from the silicon substrate to the electrodes, maximizing current collection efficiency.

[0067] Example 3

[0068] like Figure 1 As shown, based on the first embodiment, the passivation film layer 106 surrounds the second extension portion 1051 .

[0069] The coating of the passivation film layer 106 can reduce the recombination of carriers on the surface of the second extension portion 1051, further reducing electron recombination caused by surface defects, thereby improving battery performance. For example, the passivation film layer 106 can provide a chemical passivation and electric field passivation environment, which can effectively reduce the surface recombination velocity.

[0070] Furthermore, the sidewalls of the second tunneling layer 104 are flush with the sidewalls of the connected second polarity doped layer 105, the passivation film layer 106 covers the silicon substrate 101, and there is a second gap distance H between the passivation film layer 106 covering the bottom surface of the second extension portion 1051 and the passivation film layer 106 covering the silicon substrate 101, and the second gap distance is less than 150 nm.

[0071] The sidewalls of the second tunneling layer 104 are flush with the sidewalls of the connected second-polarity doped layer 105 (the sidewalls of the second-polarity doped layer 105 not including the second extension 1051), which helps reduce the impact of irregular structures on carrier transport, ensuring that current can be transmitted along a relatively smooth path, thereby improving the electrical performance and efficiency of the device. Because the side surfaces of the second-polarity doped layer 105 are spaced a first distance from the sidewalls of the recess 130, i.e., a portion of the silicon substrate 101 is exposed, the passivation film 106 covers the exposed silicon substrate 101.

[0072] The bottom surface of the second extension portion 1051 refers to the surface of the second extension portion 1051 facing the silicon substrate 101. A second gap distance is defined between the passivation film layer covering the bottom surface of the second extension portion 1051 and the passivation film layer 106 covering the silicon substrate 101. The second gap distance is less than 150 nm. This tight gap control minimizes the exposed area, maximizes passivation, and reduces unnecessary surface recombination.

[0073] Example 4

[0074] On the basis of the first embodiment, along the arrangement direction of the first region 110 and the second region 120 , the length of the first extending portion 1031 is greater than the length of the second extending portion 1051 .

[0075] The length of the first extension portion 1031 is greater than that of the second extension portion 1051. This asymmetric design is optimized for the charge separation and collection process. A longer extension portion means a larger contact area in the corresponding area, which can effectively promote the collection of charges. The longer first extension portion 1031 corresponds to the area where minority carriers are concentrated (such as electrons or holes). By increasing the contact area of ​​this part, the path for carriers to be transmitted from the silicon substrate 101 to the external circuit becomes more efficient, reducing resistance losses.

[0076] The asymmetric extension also helps optimize the potential gradient, adjusting the potential difference between different regions to encourage more efficient charge flow from one side to the other. This structural design improves the response of different regions to light, ensuring that the output current of each part of the overall circuit is matched, thereby achieving higher conversion efficiency.

[0077] Example 5

[0078] On the basis of the first embodiment, along the arrangement direction of the first region 110 and the second region 120 , the length of the first extension portion 1031 is 0.5 μm-3 μm.

[0079] In this way, controlling the length of the first extension portion 1031 within this reasonable range can avoid the first extension portion 1031 being too short and failing to effectively reduce the exchange of plasma with the outside world during the deposition of the passivation film layer 106. It can also avoid the extension portion being too long, causing the opening of the groove 130 to be too small and the etching process to be too difficult. At the same time, it can also avoid the extension portion being too long, causing easy breakage.

[0080] Specifically, in such embodiments, the length of the extension portion may be 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, or any value between 0.2 μm and 50 μm.

[0081] Example 6

[0082] On the basis of the first embodiment, along the arrangement direction of the first region 110 and the second region 120 , the length of the second extension portion 1051 is less than or equal to 200 nm.

[0083] Thus, setting the length of the second extension portion 1051 within this reasonable range can prevent the second extension portion 1051 from being too long, which may increase the resistance in the path and thus reduce the overall conductive performance and efficiency of the device.

[0084] Specifically, in such an embodiment, the length of the extension portion may be 200nm, 190nm, 180nm, 170nm, 160nm, 150nm, 140nm, 130nm, 120nm, 110nm, 100nm, 90nm, 80nm, 70nm, 60nm, 50nm, 40nm, 30nm, 20nm, 10nm or any value between 0-200nm.

[0085] Example 7

[0086] like Figure 1 As shown, in some embodiments, the surface of the second region 120 is flush with the surface of the first region 110 .

[0087] In this way, the first region 110 and the second region 120 can be directly formed using the silicon substrate 101 without performing other processes such as etching.

[0088] Example 8

[0089] like Figure 3As shown, in some embodiments, the distance between the surface of the second region 120 and the bottom of the groove 130 is smaller than the distance between the surface of the first region 110 and the bottom of the groove 130 .

[0090] In this way, when the second polarity doping layer 105 is an N-type doping layer, the surface of the battery will contact belts, rollers and other components during transportation in the production process, which will cause scratches on the surface. The alkaline solution has a higher etching rate for the N-type surface than the P-type surface. Therefore, scratches on the N-type surface will more easily cause it to be etched away in the alkaline solution, causing failure. Therefore, by sinking the N-type surface, scratches during transportation can be avoided, reducing the risk of failure.

[0091] Embodiment 9

[0092] like Figure 2 As shown, in some embodiments, the side surface of the groove 130 (ie, the surface of the bottom surface of the groove 130 connecting the surface of the first region 110 and the surface of the second region 120) is a slope.

[0093] In this way, vertical crystal planes have more defects, and by forming inclined side surfaces, the surface defects of the groove 130 can be reduced. Forming inclined side surfaces can reduce surface recombination and improve battery performance.

[0094] Example 10

[0095] Based on the first embodiment, the surface of the second extending portion 1051 facing the groove 130 has a concave-convex structure.

[0096] In this way, by forming a concave-convex texture structure on the surface, the reflection of incident light entering the silicon substrate 101 can be increased, thereby increasing the amount of light absorbed by the battery and improving the conversion efficiency of the battery.

[0097] Example 11

[0098] Based on the first embodiment, the roughness of the bottom surface of the groove 130 is greater than the roughness of the side surface of the groove 130 , and the roughness of the side surface of the groove 130 is greater than the roughness of the surfaces of the first extension portion 1031 and the second extension portion 1051 away from the groove 130 .

[0099] In this way, by providing texture structures with different roughness levels, the wettability of a local area can be improved, thereby improving the cleaning effect when cleaning the battery cell.

[0100] In addition, in some embodiments, the silicon wafer surface between the second polarity doped layer 105 and the edge of the groove 130 is a polished surface and the roughness of the surface of the extension portion facing the groove 130 is greater than the roughness of the silicon wafer surface between the second polarity doped layer 105 and the edge of the groove 130.

[0101] Example 12

[0102] Furthermore, in some embodiments, the width of the groove 130 is 2 μm-200 μm.

[0103] In this way, by setting the width of the groove 130 within this reasonable range, on the one hand, it can prevent the width of the groove 130 from being too small and failing to isolate the first polarity doped layer 103 and the second polarity doped layer 105, and on the other hand, it can prevent the width of the groove 130 from being too large and causing the ineffective area of ​​the back contact solar cell 100 to be too large.

[0104] Specifically, in such an embodiment, the width of the groove 130 may be 2μm, 4μm, 6μm, 8μm, 10μm, 20μm, 40μm, 60μm, 70μm, 100μm, 110μm, 140μm, 160μm, 170μm, 180μm or any value between 2μm-200μm, and is not limited here.

[0105] Example 13

[0106] In some embodiments, the recessed depth of the groove 130 may be 0.2 μm-10 μm.

[0107] In this way, setting the recessed depth of the groove 130 within a reasonable range here can avoid the groove 130 being too small, resulting in the groove 130 being unable to effectively isolate the substrate, and can also avoid the groove 130 being too deep, resulting in the strength of the silicon substrate 101 at the groove 130 being greatly reduced, thereby reducing the risk of cracks in the process of manufacturing the back-contact solar cell 100. In other words, if the groove 130 is too deep, it will cause the groove 130 to be thinner, resulting in the back-contact solar cell 101 being too weak at the groove 130, which is easy to cause cracks.

[0108] Specifically, in such an embodiment, the recess depth of the groove 130 may be 0.2μm, 0.4μm, 0.6μm, 0.8μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm or any value between 0.2μm and 10μm, without limitation herein.

[0109] Example 14

[0110] This embodiment provides a battery assembly, including the back-contact solar cell of the above embodiment.

[0111] The battery assembly may also include a metal frame, a backsheet, photovoltaic glass, and an adhesive film (not shown). The adhesive film may be filled between the front surface 11 of the back-contact solar cell 100 and the photovoltaic glass, the back surface and the backsheet, and adjacent cells. As a filler, it may be a transparent colloid with good light transmittance and aging resistance. For example, the adhesive film may be EVA film or POE film. The specific choice can be made according to actual conditions and is not limited here.

[0112] Photovoltaic glass can cover the adhesive film on the front surface 11 of the back-contact solar cell 100. The photovoltaic glass can be ultra-clear glass, which has high light transmittance, high transparency, and excellent physical, mechanical, and optical properties. For example, ultra-clear glass can have a light transmittance exceeding 92%, protecting the back-contact solar cell 100 while minimizing the impact on its efficiency. The adhesive film can also bond the photovoltaic glass and the back-contact solar cell 100 together, providing sealing, insulation, and waterproofing for the back-contact solar cell 100.

[0113] A backsheet can be attached to the film on the back of the back-contact solar cell 100. The backsheet protects and supports the back-contact solar cell 100, offering reliable insulation, water resistance, and aging resistance. A variety of backsheet options are available, typically including tempered glass, organic glass, and aluminum alloy TPT composite film. The specific backsheet configuration varies depending on the specific situation and is not a limitation. The backsheet, back-contact solar cell 100, film, and photovoltaic glass can be mounted on a metal frame. The metal frame serves as the primary external support structure for the entire battery assembly and provides stable support and mounting for the battery assembly. For example, the metal frame allows the battery assembly to be mounted in the desired location.

[0114] The beneficial effects of the battery assembly of this embodiment are equivalent to the beneficial effects of the above-mentioned back-contact solar cell 100, and are not described in detail here.

[0115] Example 15

[0116] This embodiment provides a photovoltaic system, including the battery assembly of the above embodiment.

[0117] Photovoltaic systems can be used in photovoltaic power stations, such as ground power stations, rooftop power stations, water-surface power stations, etc. They can also be used in equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it is understandable that the application scenarios of photovoltaic systems are not limited to this, that is, photovoltaic systems can be used in all fields that require solar power generation. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array can be an array combination of multiple battery modules. For example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box, which can combine the current generated by the photovoltaic array. The combined current flows through the inverter to be converted into the AC power required by the mains power grid and then connected to the mains power network to achieve solar power supply.

[0118] The beneficial effects of the photovoltaic system of this embodiment are equivalent to the beneficial effects of the above-mentioned battery assembly, and will not be described in detail here.

[0119] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A back contact solar cell, characterized in that: include: A silicon substrate having a backlight surface and a light-facing surface opposite to each other, first regions and second regions alternately arranged on the backlight surface of the silicon substrate, and a groove is arranged between adjacent first regions and second regions; a first tunneling layer, the first tunneling layer being stacked and covering the first region; a first polarity doped layer, wherein the first polarity doped layer is stacked on the first tunneling layer, and the first polarity doped layer has a first extending portion extending toward the groove; a second tunneling layer, the second tunneling layer being stacked on the second region; a second polarity doped layer, the second polarity doped layer being stacked on the second tunneling layer, wherein a side surface of the second polarity doped layer is spaced a first distance from a sidewall of the groove, and a second extension portion is extended from a side of the second polarity doped layer away from the silicon substrate toward the groove; and A passivation film layer covers the first polarity doped layer, the second polarity doped layer and the groove.

2. The back contact solar cell according to claim 1, wherein: The second extension portion does not extend above the groove.

3. The back contact solar cell according to claim 1, wherein: The passivation film layer surrounds the second extension portion.

4. The back contact solar cell according to claim 3, wherein: The sidewalls of the second tunneling layer are flush with the sidewalls of the connected second polarity doped layer, the passivation film layer covers the silicon substrate, and there is a second gap distance between the passivation film layer covering the bottom surface of the second extension part and the passivation film layer covering the silicon substrate, and the second gap distance is less than 150nm.

5. The back contact solar cell according to claim 1, wherein: Along an arrangement direction of the first region and the second region, a length of the first extending portion is greater than a length of the second extending portion.

6. The back contact solar cell according to claim 1, wherein: Along the arrangement direction of the first region and the second region, the length of the first extension portion is 0.5 μm-3 μm.

7. The back contact solar cell according to claim 1, wherein: Along an arrangement direction of the first region and the second region, a length of the second extension portion is less than or equal to 200 nm.

8. The back contact solar cell according to claim 1, wherein: The surface of the second region is flush with the surface of the first region.

9. The back contact solar cell according to claim 1, wherein: 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.

10. The back contact solar cell according to claim 1, wherein: The side surface of the groove is an inclined surface.

11. The back contact solar cell according to claim 1, wherein: A surface of the second extension portion facing the groove has a concavo-convex structure.

12. The back contact solar cell according to claim 1, 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 surfaces of the first extension portion and the second extension portion away from the groove.

13. The back contact solar cell according to claim 1, wherein: The width of the groove is 2um-200um.

14. The back contact solar cell according to claim 1, wherein: The recessed depth of the groove is 0.2um-10um.

15. A battery assembly, characterized in that: A back-contact solar cell comprising any one of claims 1 to 14.

16. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 15.

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