Back contact battery, battery assembly and photovoltaic system

Abstract

The utility model is suitable for the photovoltaic technology field, and provides a back contact cell, a cell assembly and a photovoltaic system, the back contact cell comprises a silicon substrate, and a first area, a spacing area and a second area are alternately arranged on the backlight surface of the silicon substrate along a first direction; the first tunneling layer is stacked in the first region; the first doping layer is stacked on the first tunneling layer; the second tunneling layer is stacked in the second region and a preset region of the interval region, and extends along the side wall, close to the first region, of the preset region to be in contact with one side, close to the second region in the first direction, of the first doping layer; the insulating medium layer is arranged on the first doping layer in a stacked mode, and the insulating medium layer is provided with an extending part extending to the interval area in the first direction in a preset area of the interval area; the second doped layer covers the first portion and the wrapping portion over the second tunneling layer. The efficiency loss caused by electric leakage contact can be reduced while the hot spot resistance of the back contact battery is improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to photovoltaic technical field especially relates to a back contact cell, battery assembly and photovoltaic system. BACKGROUND

[0002] At present, in solar cell, back contact cell is a kind of cell, which places emitter and base contact electrode on the back (non-front) of cell, and the front of the cell is not shielded by any metal electrode, thereby effectively improving the efficiency of back contact cell.

[0003] In the use process of module end, when the shelter in external environment causes the shelter of cell piece, the cell piece that is sheltered will appear hot spot phenomenon, and at high temperature, it is easy to cause the carbonization of the encapsulation adhesive film of module and even cause fire.In the back contact cell of related art, two different doped layers are usually electrically connected at local position to form leakage point, to reduce reverse breakdown voltage, thereby improving the hot spot resistance of back contact cell and reducing the risk of hot spot.However, although the current back contact cell can improve the hot spot resistance of back contact cell, it will cause the poor working performance of back contact cell and low conversion efficiency.

[0004] Therefore, how to improve the hot spot resistance of back contact cell while ensuring the conversion efficiency of back contact cell has become a technical problem to be solved by technical personnel. UTILITY MODEL CONTENTS

[0005] The utility model provides a kind of back contact cell, to solve the problem of improving the hot spot resistance of back contact cell while ensuring the conversion efficiency of back contact cell.

[0006] The utility model is realized as follows, a kind of back contact cell, comprising:

[0007] Silicon substrate, the silicon substrate has oppositely arranged back light surface and light surface, first area, interval area and second area are alternately arranged on the back light surface of the silicon substrate along first direction, the first area, interval area and second area extend along second direction, and the second direction intersects with the first direction;

[0008] First tunneling layer, the first tunneling layer is laminated in the first area;

[0009] First doped layer, the first doped layer is laminated on the first tunneling layer;

[0010] Second tunneling layer, the second tunneling layer is laminated in the second area and interval area preset area, and extend along the side wall of the preset area close to the first area to contact with the first doped layer along first direction close to the second area one side;

[0011] an insulating medium layer, the insulating medium layer is arranged on the first doped layer in a stack manner, and in a preset region of the interval region, the insulating medium layer has an extension part extending to the interval region along the first direction, wherein the length of the extension part in the first direction is greater than the length of the first doped layer in the first direction;

[0012] a second doped layer, the second doped layer covers the first part and a wrapping part of the second tunneling layer, the wrapping part wraps around opposite sides of the insulating medium layer in the thickness direction of the cell sheet, and a side of the insulating medium layer close to the second doped layer along the first direction, and the second doped layer is different in polarity from the first doped layer.

[0013] Optionally, along a first cross section in the first direction, the difference between the distances between different positions of the extension part and the surface of the silicon substrate is less than or equal to 30 nm.

[0014] Optionally, along a second cross section in the first direction, the extension part extends towards the bottom surface of the second region, and one end of the wrapping part along the first direction is not in contact with the first part.

[0015] Optionally, along a third cross section in the first direction, the extension part extends towards the bottom surface of the second region, one end of the wrapping part close to the second region is in contact with the first part, and a hollow is formed between the wrapping part and the first part.

[0016] Optionally, along a fourth cross section in the first direction, the extension part extends towards the bottom surface of the second region, and the extension part is not in contact with the second tunneling layer, the wrapping part is in contact with the first part, and there is no hollow between the wrapping part and the first part.

[0017] Optionally, along a fifth cross section in the first direction, the extension part extends towards the bottom surface of the second region, and the extension part is in contact with the second tunneling layer, and there is no hollow between the wrapping part and the first part.

[0018] Optionally, a through hole is formed on the extension part, and the through hole communicates the second doped layers on both sides of the extension part.

[0019] Optionally, the outer diameter size of the hollow is 10 nm-500 nm.

[0020] Optionally, along the first direction, the first doped layer has a protruding part extending outwards to the second region, and the second tunneling layer covers the protruding part towards the surface of the silicon substrate.

[0021] Optionally, the included angle between the surface of the first doped layer forming the electric leakage contact and the surface of the silicon substrate is an acute angle, and the first doped layer has a first recessed area on the side surface facing the second region.

[0022] Optionally, the side surface of the first doped layer is a curved surface.

[0023] Optionally, in the first direction, the silicon substrate has a silicon wafer extension extending over the interval, and the first doped layer is also arranged on the silicon wafer extension, the cross-sectional profile of the silicon wafer extension is a triangle, and the included angle between the surface of the silicon wafer extension facing the second region and the surface of the first region is an acute angle.

[0024] Optionally, the extension length of the silicon wafer extension in the first direction is 0.1-3 μm.

[0025] The new type also provides a battery assembly comprising the back contact battery.

[0026] The new type also provides a photovoltaic system comprising the battery assembly.

[0027] The beneficial effects achieved by the utility model are that the first tunneling layer and the first doped layer are arranged on the first region, the second tunneling layer is arranged in a preset region of the second region and the interval region in a stacked manner and extends along the side wall of the preset region close to the first region to contact the side of the first doped layer close to the second region in the first direction. The insulating medium layer is arranged in a stacked manner on the first doped layer, and in the preset region of the interval region, the insulating medium layer has an extension part extending to the interval region in the first direction. The second doped layer covers the second tunneling layer and the insulating medium layer in a wrapped manner. The second doped layer and the first doped layer form electric leakage contact at the position of the side wall close to the first region in the preset region, thereby improving the hot spot resistance of the back contact battery. At the same time, the extension part of the insulating medium layer is used to improve the passivation effect at the electric leakage contact position, thereby optimizing the efficiency of the back contact battery. In addition, the wrapped design of the second doped layer can increase the contact area with the second tunneling layer, ensure that the electric contact points on the second region and the interval region are more reliable, and help to improve the charge collection efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a schematic diagram of the planar structure of the back contact battery provided by the embodiment of the application;

[0029] Figure 2 is Figure 1 is a sectional view along line A-A of the back contact battery in

[0030] Figure 3 is Figure 1A cross-sectional view of the back contact battery along line BB;

[0031] Figure 4 yes Figure 1 A cross-sectional view of the back contact battery along line CC.

[0032] Figure 5 yes Figure 1 A cross-sectional view of the back contact battery along line DD;

[0033] Figure 6 yes Figure 1 A cross-sectional view of the back contact battery along line EE;

[0034] Figure 7 yes Figure 1 A cross-sectional view of the back contact battery along line FF;

[0035] Figure 8 This is a cross-sectional schematic diagram of a back contact battery provided in an embodiment of this application;

[0036] Figure 9 This is another cross-sectional view of the back contact battery provided in an embodiment of this application;

[0037] Explanation of reference numerals in the attached figures:

[0038] 100. Back contact cell; 101. Silicon substrate; 1011. Silicon wafer extension; 110. First region; 120. Second region; 130. Spacing region; 1031. Preset position; 102. First tunneling layer; 103. First doped layer; 1031. Protruding portion; 1032. First recessed region; 104. Second tunneling layer; 105. Insulating dielectric layer; 1051. Extension portion; 1052. Through hole; 106. Second doped layer; 1061. First portion; 1062. Wrapped portion; 1063. Void. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this utility model and are not intended to limit this utility model.

[0040] In the description of the utility model, it is necessary to understand that the orientation or positional relation indicated by the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom" and the like is the orientation or positional relation based on the drawing shown, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the utility model.

[0041] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the utility model, the meaning of "multiple" is two or more than two, unless otherwise specifically limited.

[0042] In the description of the utility model, it should be noted that, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; can be mechanical connection, or electrical connection or can communicate with each other; can be directly connected, or indirectly connected through an intermediate medium, can be the communication or interaction between two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0043] In the utility model, unless otherwise specifically defined and limited, the "upper" or "lower" of the first feature in the second feature can include the direct contact of the first and second features, or the indirect contact of the first and second features through another feature between them. Moreover, the "upper", "upper" and "upper" of the first feature in the second feature include the vertical and inclined upper of the first feature in the second feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The "below", "below" and "below" of the first feature in the second feature include the vertical and inclined lower of the first feature in the second feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0044] The disclosure below provides many different embodiments or examples for implementing different structures of the present application. For the sake of simplicity, the description below of the specific examples will not be exhaustive of the disclosure. Indeed, the present application can be practiced in a variety of ways. Obviously, they are merely examples of implementing the present application and are not intended to limit its scope, either for purposes of patent law or otherwise. Furthermore, well-known methods of making and using the claimed application have not been described in detail in order to avoid unnecessarily obscuring the present application. Also, the present application provides examples of various specific processes and materials. However, it is contemplated that others can embody the application in different ways, for example, using other processes and / or materials.

[0045] The first tunneling layer and the first doped layer are arranged on the first region, the second tunneling layer is arranged in the preset region of the second region and the interval region in a stacked manner, and extends along the side wall of the preset region close to the first region to contact the side of the first doped layer close to the second region in the first direction. The insulating medium layer is arranged on the first doped layer in a stacked manner, and in the preset region of the interval region, the insulating medium layer has an extension part extending to the interval region in the first direction. The second doped layer covers the second tunneling layer and the insulating medium layer in a wrapped manner. The second doped layer and the first doped layer form a leakage contact at the position of the side wall close to the first region in the preset region, thereby improving the hot spot resistance of the back contact battery. At the same time, the extension part of the insulating medium layer improves the passivation effect and optimizes the efficiency of the back contact battery. In addition, the wrapping design of the second doped layer can increase the contact area with the second tunneling layer, ensure that the electrical contact points on the second region and the interval region are more reliable, and help to improve the charge collection efficiency.

[0046] Example One

[0047] As shown in Figure 1 and Figure 2 The embodiment provides a back contact battery 100, which comprises:

[0048] A silicon substrate 101, the silicon substrate 101 has a back light surface and a light surface arranged oppositely, the first region 110, the interval region 130 and the second region 120 are arranged alternately on the back light surface of the silicon substrate 101 in the first direction, and the first region 110, the interval region 130 and the second region 120 extend in the second direction, and the second direction intersects with the first direction;

[0049] A first tunneling layer 102, the first tunneling layer 102 is arranged in a stacked manner on the first region 110;

[0050] A first doped layer 103, the first doped layer 103 is arranged in a stacked manner on the first tunneling layer 102;

[0051] The second tunneling layer 104 is stacked in a preset region of the second region 120 and the spacer region 130, and extends along the side wall of the preset region near the first region 110, and contacts the side of the first doped layer 103 near the second region 120 in the first direction.

[0052] An insulating dielectric layer 105 is stacked on the first doped layer 103 and has an extension portion 1051 extending along a first direction to the spacer region 130, wherein the length of the extension portion 1051 in the first direction is greater than the length of the first doped layer 103 in the first direction.

[0053] The second doped layer 106 covers the first portion 1061 and the wrapping portion above the second tunneling layer 104. The wrapping portion wraps around the insulating dielectric layer 105 on both sides opposite to each other along the thickness direction of the cell, and on the side of the insulating dielectric layer 105 close to the second doped layer 106 along the first direction. The second doped layer 106 has a different polarity from the first doped layer 103.

[0054] The silicon substrate 101 has two main surfaces: a light-facing surface and a back-lighting surface. The light-facing surface directly faces the sunlight, while the back-lighting surface is on the other side. The two surfaces are positioned opposite each other.

[0055] Three distinct regions—a first region 110, a spacer region 130, and a second region 120—are arranged alternately on the backlight surface of the silicon substrate 101. Specifically, a plurality of first regions 110 and a plurality of second regions 120 are alternately arranged along a first direction. A spacer region 130 is provided between the first regions 110 and the second regions 120, meaning adjacent first regions 110 and second regions 120 are separated by the spacer region 130. The first regions 110, spacer regions 130, and second regions 120 all extend along a second direction, which intersects the first direction. The first regions 110, spacer regions 130, and second regions 120 can be alternately arranged along the transverse direction of the silicon substrate 101 and both extend along the longitudinal direction. That is, the first direction can be the transverse direction of the back contact battery 100, and the second direction can be the longitudinal direction of the back contact battery 100, with the two directions perpendicular to each other. Of course, in other embodiments, the first and second directions can also be other directions; for example, they can be the diagonal directions of the silicon substrate 101, and no specific limitation is made here.

[0056] As one case, such as Figure 2 As shown, in the direction from the light-facing surface to the backlight-facing surface, the surface of the first region 110 may be higher than the surfaces of the spacer region 130 and the second region 120. That is, in the thickness direction of the silicon substrate 101, the spacer region 130 and the second region 120 are closer to the light-facing surface of the silicon substrate domain than the first region 110.

[0057] The first tunneling layer 102 is arranged on the first region 110, and the first doped layer 103 is arranged on the first tunneling layer 102. The tunneling layer can be silicon oxide (SiOx), silicon nitride (SiNx) or the like, which forms a tunnel effect, allows electrons or holes to pass through efficiently, reduces resistance loss, and improves the extraction efficiency of charge carriers.

[0058] The second tunneling layer 104 is arranged on the second region 120 and the preset region of the isolation region, and extends along the sidewall of the isolation region close to the first region 110 and contacts the first doped layer 103. It can be understood that, since the first doped layer 103 is arranged on the first tunneling layer 102, the side of the first tunneling layer 102 close to the isolation region 130 becomes part of the sidewall of the isolation region close to the first region 110. During the process that the second tunneling layer 104 extends along the sidewall of the isolation region close to the first region 110 and contacts the first doped layer 103, the second tunneling layer 104 must contact the first tunneling layer 102, that is, the second tunneling layer 104 contacts the first tunneling layer 102 and the first doped layer 103. The second tunneling layer 104 can be made of the same material as the first tunneling layer 102, or can be made of a different material, which is not limited here.

[0059] The insulating medium layer 105 is arranged on at least part of the first doped layer 103, and has an extension part 1051 extending to the isolation region 130 in the first direction in the preset region of the isolation region. The length of the extension part 1051 in the first direction is greater than the length of the first doped layer 103 in the first direction. That is, the extension part 1051 extends in the first direction to protrude (or exceed) the first doped layer 103.

[0060] The second doped layer 106 includes a first part 1061 covering the second tunneling layer 104 and a wrapping part wrapping around the opposite sides of the insulating medium layer 105 in the thickness direction of the battery sheet and the side of the insulating medium layer 105 close to the second doped layer 106 in the first direction, and the polarity of the second doped layer 106 is different from that of the first doped layer 103. The first part 1061 covers the second tunneling layer 104, that is, no matter where and in which direction the second tunneling layer 104 is arranged, the outer layer of the second tunneling layer 104 covers the first part 1061. The second doped layer 106 is arranged to cover and wrap the outermost exposed contour of the well-arranged first tunneling layer 102, first doped layer 103, second tunneling layer 104 and insulating medium layer 105 (only the second tunneling layer 104 and the insulating medium layer 105 are actually exposed to the outermost layer).

[0061] The polarities of the first doped layer 103 and the second doped layer 106 are different, specifically, the first doped layer 103 can be a P-type doped layer and the second doped layer 106 can be an N-type doped layer, or the first doped layer 103 can be an N-type doped layer and the second doped layer 106 can be a P-type doped layer. The first and second doped layers form regions with different electrical properties, supporting the formation of PN junctions and the separation of charge carriers.

[0062] In the first region 110, the insulating medium layer 105 is arranged between the first doped layer 103 and the second doped layer 106 to electrically isolate the first doped layer 103 and the second doped layer 106, avoiding the formation of a large-area electrical contact between the first doped layer 103 and the second doped layer 106 in the first region 110. In a preset position near the sidewall of the first region 110, the second doped layer 106 and the first doped layer 103 form a leakage contact through the second tunneling layer 104. In this context, the "leakage contact" refers to the absence of insulation between the first doped layer 103 and the second doped layer 106, and instead forms a leakage point for electrical conduction.

[0063] When the solar cell is normally generating electricity, the leakage contact region between the first doped layer 103 and the second doped layer 106 also undergoes photoelectric conversion to generate electricity, thereby increasing the power generation of the solar cell. When the solar cell is shaded and insufficient light causes the current output of the shaded part to decrease, the voltage of this part increases, and the leakage contact region forms a conductive path, providing a reverse current for the shaded solar cell from the other solar cells in series with it. A suitable composite leakage current can be generated between the first doped layer 103 and the second doped layer 106 of the solar cell, reducing the voltage across the shaded solar cell (exemplarily, the voltage is less than the sum of the voltages of the other solar cells in series with the solar cell and not shaded), and reducing the heat generation of the solar cell, thereby reducing the high-heat risk of the hot spot effect.

[0064] It should be noted that in the embodiments of the present application, the "preset position 1301" can be understood as the entire spacing region 130 or a part of the spacing region 130, and the specific implementation is not limited herein. As shown in FIG. 1B, in some embodiments, the preset position 1301 is preferably a part of the spacing region 130, and in such a case, the number of preset positions 1301 in each spacing region 130 can be single or multiple, as shown in FIG. 1C. Figure 1 Figure 1 As shown in FIG. 1C, in a single spacing region 130, multiple preset positions 1301 can be arranged at intervals along the second direction, and the specific implementation is not limited herein.

[0065] ​In addition, in the embodiments of the present application, the number of the interval regions 130 with the preset positions 1301 can be single or multiple, which is not limited here. Further, in some embodiments, the number of the preset positions 1301 can be multiple, which can be uniformly distributed on the back surface of the back contact battery 100.

[0066] The insulating medium layer 105 can be a medium layer with insulating function, for example, in some embodiments, the insulating medium layer 105 can be a borosilicate glass layer, a phosphosilicate glass layer or a borophosphosilicate glass layer. For another example, in some embodiments, the insulating medium layer 105 can be a silicon oxide layer, a silicon nitride layer or the like with insulating function. In addition, in some embodiments, the insulating medium layer 105 can be a single layer structure or a multi-layer structure, which is not limited here.

[0067] In the present embodiment, the first tunneling layer 102 and the first doped layer 103 are arranged on the first region 110, the second tunneling layer 104 is arranged in the preset region of the second region 120 and the interval region 130 and extends along the sidewall of the first region 110 close to the second region 120 to contact the first doped layer 103. The insulating medium layer 105 is arranged on the first doped layer 103, and in the preset region of the interval region, the insulating medium layer 105 has an extension part 1051 extending to the interval region 130 along the first direction. The second doped layer 106 covers the second tunneling layer 104 and the insulating medium layer 105. The second doped layer 106 and the first doped layer 103 form a leakage contact at the sidewall position close to the first region 110 in the preset region, thereby improving the hot spot resistance of the back contact battery 100. At the same time, the extension part 1051 of the insulating medium layer 105 improves the passivation effect at the leakage contact position, thereby optimizing the efficiency of the back contact battery 100. In addition, the covering design of the second doped layer 106 can increase the contact area with the second tunneling layer 104, thereby ensuring that the electrical contact points on the second region 120 and the interval region are more reliable, thereby helping to improve the charge collection efficiency.

[0068] In addition, in the embodiments of the present application, the back contact battery 100 can further include a first electrode (not shown) and a second electrode (not shown), and a back passivation film layer (not shown) can be arranged on the back surface of the silicon substrate 101, which can cover the entire back surface. The first electrode can be located at the first region 110 and form an ohmic contact with the first doped layer 103 through the back passivation film layer and be insulated from the second doped layer 106. For example, the first electrode can be located at the position of the first doped layer 103 which is not covered by the extension part 1051, and the second electrode can be located at the second region 120 and form an ohmic contact with the second doped layer 106 through the back passivation film layer.

[0069] Example Two

[0070] In some embodiments, the difference in distance between different locations of the extension portion 1051 and the surface of the silicon substrate 101 along the first cross section in the first direction is less than or equal to 30 nm.

[0071] like Figure 2 As shown, at the first cross-section along the first direction ( Figure 2 This is a cross-sectional view of the first section, which is... Figure 1 The extension portion 1051 extends into the spacer region 130 at one of the cross sections formed along line AA in the first direction. That is, along the first direction, the extension portion 1051 has multiple cross sections, which are arranged in parallel along the second direction. It should be noted that, in this document, the cross section along the first direction refers to the cross section taken from the back contact battery 100 along the first direction.

[0072] At the first cross-section, the extension portion 1051 extends in a direction parallel to the surface of the silicon substrate 101, and the extension portion 1051 is approximately parallel to the surface of the silicon substrate 101. The wrapping portion of the second doped layer 106 wraps around the extension portion 1051, that is, the wrapping portion 1062 is attached to the outer surface of the extension portion 1051. Since the extension portion 1051 has a regular shape, it is conducive to the attachment of the second doped layer 106. At the location where the second doped layer 106 and the first doped layer 103 form leakage doping, a stable doped structure can also be formed, which helps to stably reduce the reverse breakdown voltage at this location, reduce the risk of breakdown under high reverse voltage, increase the leakage effect of the bypass diode when the cell has hot spots, effectively bypass the current, and reduce local overheating.

[0073] Example Three

[0074] like Figure 3 As shown, in some embodiments, the second cross section along the first direction ( Figure 3 This is a schematic cross-sectional view at the second section. For example, the second section can be... Figure 1 The section formed by the middle line BB), the extension portion 1051 extends toward the bottom surface of the second region 120, and one end of the wrapping portion along the first direction does not contact the first portion 1061.

[0075] It can be understood that, by adopting the scheme of the embodiment, the extension part 1051 is arranged to extend towards the bottom surface of the second region 120, which can significantly reduce the process difficulty; and during the formation of the film layer (for example, the second tunneling layer, the second doped layer), the extension part 1051 extending towards the bottom surface of the second region 120 does not have a great impact on the deposition process, and thus a stable electric leakage contact structure can be formed.

[0076] In addition, it can be understood that the incident light entering the interior of the battery piece from the light-receiving surface of the battery piece can further reach the extension part 1051 from multiple directions, and thus the extension part 1051 is arranged in multiple forms, for example, the form in Embodiment Two and the form in Embodiment Three, which can further reflect the incident light reaching the extension part 1051 to the interior of the battery piece, and improve the light absorption rate.

[0077] Example Four

[0078] As shown in Figure 4 , in some embodiments, the third cross section (the cross section along line B-B in Figure 4 , that is, the cross-sectional view at the fourth cross section) in the first direction extends towards the bottom surface of the second region 120, the end of the wrapping part close to the second region 120 is in contact with the first part 1061, and the hollow 1063 is formed between the wrapping part and the first part 1061. Figure 1

[0079] It can be understood that, by adopting the scheme of the embodiment, the difficulty of further depositing the passivation layer and the anti-reflection layer on the second doped layer can be reduced, the quality of the passivation layer and the anti-reflection layer can be improved, and the passivation and anti-reflection effects can be improved.

[0080] In addition, it can be understood that the incident light entering the interior of the battery piece from the light-receiving surface of the battery piece can further reach the extension part 1051 from multiple directions, and thus the extension part 1051 is arranged in multiple forms, for example, the form in Embodiment Two and the form in Embodiment Four, which can further reflect the incident light reaching the extension part 1051 to the interior of the battery piece, and improve the light absorption rate.

[0081] In some embodiments, the outer diameter size of the hollow 1063 is 10 nm-500 nm.

[0082] In this way, the local stress of the second doped layer 106 can be released by the hollow 1063, and the contact area of the second doped layer 106 forming the electric leakage contact with the first doped layer 103 through the second tunneling layer 104 is not affected.

[0083] ​Specifically, in such an embodiment, the outer diameter of the cavity 1063 can be, for example, any value between 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, or 10nm-500nm.

[0084] Example Five

[0085] like Figure 5 As shown, in some embodiments, the fourth section along the first direction ( Figure 5 This is a schematic cross-sectional view at the fourth section. For example, the fourth section can be... Figure 1 The extension portion 1051 extends toward the bottom surface of the second region 120 (the cross section formed by the middle line DD), and the extension portion 1051 does not contact the second tunnel layer 104. The wrapping portion contacts the first portion 1061, and there is no void 1063 between the wrapping portion and the first portion 1061.

[0086] It is understood that by adopting the solution of this embodiment, the difficulty of further depositing a passivation layer and an antireflection layer on the second doped layer can be reduced, the quality of the passivation layer and the antireflection layer can be improved, and the passivation and antireflection effects can be enhanced.

[0087] Furthermore, it is understood that incident light entering the interior of the solar cell from the light-facing surface of the solar cell may further reach the extension portion 1051 from multiple directions. Therefore, the extension portion 1051 is configured in various forms, such as the forms in Embodiment 2 and Embodiment 5, so that the incident light reaching the extension portion 1051 can be further reflected into the interior of the solar cell, thereby improving the light absorption rate.

[0088] Example Six

[0089] like Figure 6 As shown, in some embodiments, the fifth section along the first direction ( Figure 6 This is a schematic cross-sectional view at the fifth section. For example, the fifth section can be... Figure 1 The extension portion 1051 extends toward the bottom surface of the second region 120 (the cross section formed by the EE along the middle line), and the extension portion 1051 contacts the second tunnel layer 104. There is no void 1063 between the wrapping portion and the first portion 1061.

[0090] The extension portion 1051 extends towards the bottom surface of the second region 120 until it contacts the second tunneling layer 104, that is, the extension portion 1051 and the second tunneling layer 104 form a closed space. Parts of the wrapping portion 1062 and the first portion 1061 of the second doped layer 106 are enclosed within this closed space, while other portions are located outside the closed space. There is no gap between the wrapping portion 1062 and the first portion 1061; that is, the wrapping portion 1062 and the first portion 1061 enclosing the closed space completely fill the closed space (the second doped layer 106 completely fills the closed space), and the wrapping portion 1062 and the first portion 1061 located outside the closed space are in contact with each other without any voids 1063 at the contact point.

[0091] The design of this enclosed space surrounds the side of the extension 1051 facing the silicon substrate 101 inside the back contact cell 100, thereby relatively reducing its specific surface area. A smaller specific surface area can reduce the surface state density per unit area of ​​the cell, reduce the surface recombination rate, which is beneficial to improving the open circuit voltage and conversion efficiency of the cell, as well as extending the carrier lifetime, allowing more carriers to participate in energy conversion and improving the overall performance of the cell.

[0092] In summary, in this application, at different cross-sections, the extension portion 1051 and the second tunnel layer 104 form different shapes. At some cross-sections, they form a closed shape, and at other cross-sections, they form a non-closed shape.

[0093] like Figure 7 As shown, in some embodiments, a through hole 1052 is formed on the extension portion 1051. Figure 7 This is a schematic cross-sectional view at the sixth section. For example, the sixth section can be... Figure 1 (The cross section formed by the line FF in the middle), the through hole 1052 connects the second doped layer 106 on both sides of the extension portion 1051.

[0094] Compared to the fifth section, the sixth section has a through-hole 1052 on the extension 1051. By forming the through-hole 1052 on the extension 1051, it is convenient to deposit the second doped layer 106 in the closed space enclosed by the extension 1051 and the second tunneling layer 104. At the same time, the second doped layer 106 inside and outside the closed space can form a conductive contact through the through-hole 1052. In other continuous positions, the second doped layer 106 inside and outside the closed space is isolated by the extension 1051, which can avoid the second doped layer 106 inside and outside the closed space from forming contact and causing excessive efficiency loss, and can also improve the passivation effect.

[0095] Specifically, in such an embodiment, the through hole 1052 on the extension portion 1051 can be single or multiple, and no specific limitation is made here.

[0096] like Figure 7 As shown, at the sixth cross-section, the extension 1051 and the second tunneling layer 104 form a closed pattern. At the fifth cross-section, the extension 1051 and the second tunneling layer 104 together form a non-closed pattern with an opening, which allows the second doped layer 106 to connect through the opening of the non-closed pattern, thereby enabling the first doped layer 103 and the second doped layer 106 to form a leakage contact. This design of the extension 1051 reduces the efficiency loss caused by leakage contact.

[0097] Example Seven

[0098] like Figure 8 As shown, in some embodiments, along a first direction, a first doped layer 103 has a protrusion 1031 extending into a second region 120, and a second tunneling layer 104 covers the surface of the protrusion 1031 toward the silicon substrate 101.

[0099] Both the extension portion 1051 and the protrusion portion 1031 extend towards the second region 120, but the extension length of the extension portion 1051 is greater than that of the protrusion portion 1031. The side surface of the protrusion portion facing away from the silicon substrate 101 contacts the insulating dielectric layer 105, and the side surface of the protrusion portion facing the silicon substrate 101 is covered by a second doped layer 106. The protrusion portion is a part of the first doped layer 103, and the side of the protrusion portion near the second region 120 is the side surface of the first doped layer 103, which contacts the second tunneling layer 104. The second doped layer 106 covers the second tunneling layer 104, and also correspondingly covers the second tunneling layer 104 on the side surface of the protrusion portion facing the silicon substrate 101. The protrusion portion 1031 increases the contact area of ​​the leakage contact between the first doped layer 103 and the second doped layer 106, thereby optimizing electrical contact and charge transport performance.

[0100] Example Eight

[0101] like Figure 9 As shown, in some embodiments, the angle between the surface of the first doped layer 103 and the second doped layer 106 forming a leakage contact and the surface of the silicon substrate 101 is an acute angle, and the first doped layer 103 has a first recessed region 1032 on the side facing the second region 120.

[0102] Thus, by setting the angle between the leakage contact surface of the first doped layer 103 and the surface of the first region 110 to an acute angle and forming a first recessed region 1032201 on the leakage contact surface, the second doped layer 106 can be deposited more easily to form a leakage contact with the first doped layer 103.

[0103] Furthermore, in such an embodiment, the surface where the first doped layer 103 and the second doped layer 106 form a leakage contact is curved. This increases the leakage contact area between the first doped layer 103 and the second doped layer 106, thereby improving the resistance to hot spots.

[0104] It is understood that in any preset region of the solar cell, or in different preset regions, the multiple cross sections along the first direction can be one of Embodiments 2 to 8, or a combination of at least two of them. Specifically, it can be a combination of Embodiments 2 and 3, a combination of Embodiments 3 and 4, a combination of Embodiments 4, 5, and 6, a combination of Embodiments 2, 4, 6, and 7, a combination of Embodiments 3, 5, 7, and 8, or all combinations of Embodiments 2 to 8. No exhaustive list has been given, and other combinations are not excluded. The adjacent cross sections are parallel to each other along the second direction. Incident light entering the interior of the solar cell from the light-facing surface may further reach the extension portion 1051 from multiple directions. Therefore, the extension portion 1051 is configured in various forms to further reflect the incident light reaching the extension portion 1051 into the interior of the solar cell, thereby improving the light absorption rate.

[0105] Example Nine

[0106] like Figure 8 and 9 As shown, in some embodiments, in a first direction, the silicon substrate 101 has a silicon wafer extension 1011 extending and suspended over the spacer, and the silicon wafer extension 1011 is also provided with a first doped layer 103. The cross-sectional profile of the silicon wafer extension 1011 is triangular, and the angle between the surface of the silicon wafer extension 1011 facing the second region 120 and the surface of the first region is an acute angle.

[0107] In a first direction, the silicon substrate 101 has a silicon wafer extension 1011 extending and suspended over the spacer region 130. The silicon wafer extension 1011 is also provided with a first doped layer 103 (i.e., the upper surface of the silicon wafer extension 1011 shown in the figure is provided with the first doped layer 103). The cross-sectional profile of the silicon wafer extension 1011 is triangular, and the angle between the surface of the silicon wafer extension 1011 facing the spacer region 130 and the surface of the first region 110 (i.e., the lower surface of the silicon wafer extension 1011 shown in the figure) is an acute angle.

[0108] Therefore, the side surface of the interval region 130 of the silicon substrate 101 can have a concave structure by controlling the etching process, and the diffusion of the gas source can be limited in the deposition process of the second doped layer 106, so as to effectively reduce the doping concentration of the second doped layer 106 and the silicon substrate, reduce the interface recombination rate, improve the carrier collection probability, and effectively eliminate the local stress.

[0109] In some embodiments, the extension length of the silicon wafer extension 1011 in the first direction can be 0.1 μm-3 μm.

[0110] Therefore, by controlling the extension length of the silicon wafer extension 1011 in the first direction to be within the reasonable range, the interface recombination rate can be further optimized to achieve a better carrier collection efficiency.

[0111] Specifically, the extension length of the silicon wafer extension 1011 in the first direction can be, for example, 0.1 μm, 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, or any value between 0.1 μm and 3 μm.

[0112] Example Nine

[0113] The embodiment also provides a battery assembly including the back contact battery 100.

[0114] The battery assembly can include a plurality of back contact solar cell pieces, and the plurality of back contact solar cell pieces in the battery assembly can be sequentially connected together to form a battery string, and each battery string can be connected in series, in parallel, or in a combination of series and parallel, to realize the current output, for example, the connection between the cell pieces can be realized by welding the solder strips, and the connection between the battery strings can be realized by the bus bars.

[0115] The battery assembly can further include a metal frame, a back plate, a photovoltaic glass, and a glue film (not shown in the figures). The glue film can be filled between the front surface of the back contact battery 100 and the photovoltaic glass, the back surface and the back plate, and adjacent cell pieces, as a filler, which can be a transparent glue with good light transmission and aging resistance, for example, the glue film can be an EVA glue film or a POE glue film, which can be selected according to the actual situation, and is not limited herein.

[0116] The photovoltaic glass can be covered on the adhesive film on the front surface of the back contact cell 100. The photovoltaic glass can be super white glass, which has high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, the light transmittance of the super white glass can be more than 92%, which can protect the back contact cell 100 without affecting the efficiency of the back contact cell 100 as much as possible. At the same time, the adhesive film can bond the photovoltaic glass and the back contact cell 100 together, and the presence of the adhesive film can seal and insulate the back contact cell 100 and prevent water and moisture.

[0117] The back plate can be attached to the adhesive film on the back surface of the back contact cell 100. The back plate can protect and support the back contact cell 100, has reliable insulation, water resistance, and aging resistance. The back plate can have multiple choices, which can be tempered glass, organic glass, aluminum alloy TPT composite adhesive film, etc. The specific setting can be made according to the specific situation, which is not limited here. The whole composed of the back plate, the back contact cell 100, the adhesive film, and the photovoltaic glass can be arranged on the metal frame. The metal frame serves as the main external support structure of the entire cell assembly, and can stably support and install the cell assembly. For example, the cell assembly can be installed at the desired installation position through the metal frame.

[0118] The beneficial effects of the cell assembly of the present embodiment are the same as those of the above-mentioned back contact cell 100, which are not repeated here.

[0119] Example Ten

[0120] The present embodiment also provides a photovoltaic system comprising the above-mentioned cell assembly.

[0121] The photovoltaic system can be applied in a photovoltaic power station, such as a ground power station, a roof power station, a water surface power station, etc. It can also be applied in a device or apparatus that uses solar energy to generate electricity, such as a user solar power source, a solar street lamp, a solar car, a solar building, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is, the photovoltaic system can be applied in all fields that need to use solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system can include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array can be an array combination of multiple cell assemblies. For example, multiple cell assemblies can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box. The combiner box can combine the current generated by the photovoltaic array. The combined current flows through the inverter to convert into alternating current required by the power grid, and then is connected to the power grid to realize solar power supply.

[0122] The beneficial effects of the photovoltaic system of the present embodiment are the same as those of the above-mentioned cell assembly, which are not repeated here.

[0123] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application, and any modification, equivalent replacement, and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A back contact cell, characterized in that, The application relates to a silicon substrate with a back light surface and a light surface, a first region, a spacer region and a second region being alternately arranged on the back light surface of the silicon substrate along a first direction, the first region, the spacer region and the second region extending along a second direction intersecting the first direction, a first tunnel layer being arranged on the first region, a first doped layer being arranged on the first tunnel layer, a second tunnel layer being arranged on the second region and the spacer region, the second tunnel layer extending along the sidewall of the first region close to the second region, an insulating medium layer being arranged on the first doped layer, the insulating medium layer having an extension part extending to the spacer region along the first direction, the length of the extension part along the first direction being greater than the length of the first doped layer along the first direction, a second doped layer being arranged on the second tunnel layer, the second doped layer having a first part and a surrounding part, the surrounding part surrounding the two sides of the insulating medium layer along the thickness direction of the cell piece and the side of the insulating medium layer close to the second doped layer along the first direction, the polarity of the second doped layer being different from that of the first doped layer. The distance difference between different positions of the extension part and the surface of the silicon substrate along the first direction is less than or equal to 30 nm. The extension part extends towards the bottom surface of the second region along the first direction, and one end of the surrounding part along the first direction is not in contact with the first part. The extension part extends towards the bottom surface of the second region along the first direction, one end of the surrounding part close to the second region is in contact with the first part, and a cavity is formed between the surrounding part and the first part. The extension part extends towards the bottom surface of the second region along the first direction, the extension part is not in contact with the second tunnel layer, the surrounding part is in contact with the first part, and no cavity is formed between the surrounding part and the first part. The extension part extends towards the bottom surface of the second region along the first direction, and the extension part is in contact with the second tunnel layer, and no cavity is formed between the surrounding part and the first part. A through hole is formed on the extension part, and the through hole is in communication with the second doped layer on both sides of the extension part.

2. The back contact cell of claim 1, wherein, The outer diameter of the cavity is 10-500 nm.

3. The back contact cell of claim 1, wherein, The first doped layer has a protruding part extending to the second region along the first direction, and the second tunnel layer covers the surface of the protruding part towards the surface of the silicon substrate.

4. The back contact cell of claim 1, wherein, The surface of the first doped layer and the second doped layer forming the leakage contact forms an acute angle with the surface of the silicon substrate, and the first doped layer has a first recessed area on the side surface towards the second region.

5. The back contact cell of claim 1, wherein, The side surface of the first doped layer is a curved surface.

6. The back contact cell of claim 1, wherein, ​ 7. The back contact cell of claim 6, wherein, ​ 8. The back contact cell of claim 4, wherein, ​ 9. The back contact cell of claim 1 wherein, ​ 10. The back contact cell of claim 1, wherein, ​ 11. The back contact cell of claim 10, wherein, ​ 12. The back contact cell of claim 1 wherein, In the first direction, the silicon substrate has a silicon wafer extension extending overhanging onto the spacing, the silicon wafer extension also being provided with the first doped layer, the cross-sectional profile of the silicon wafer extension being triangular, and the angle between the surface of the silicon wafer extension towards the second region and the surface of the first region being an acute angle.

13. The back contact cell of claim 12, wherein, The silicon wafer extension has an extension length in the first direction of 0.1 μm to 3 μm.

14. A battery assembly characterized by, A back contact cell comprising a plurality of back contact cells according to any one of claims 1 to 13.

15. A photovoltaic system characterized by, A battery assembly comprising a battery assembly according to claim 14.

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