Back contact battery and photovoltaic module

Abstract

The embodiment of the utility model relates to the photovoltaic field, and provides a back contact battery and a photovoltaic module, and the back contact battery comprises a substrate which is provided with a first surface and a second surface which are oppositely arranged; p-type doped conductive layers and N-type doped conductive layers, wherein the P-type doped conductive layers and the N-type doped conductive layers are alternately arranged on the second surface at intervals; the plurality of first fine grids are arranged on the second surface at intervals along the first direction, and the first fine grids are in electric contact with the P-type doped conductive layer; the plurality of second fine grids are arranged on the second surface at intervals along the first direction, the second fine grids and the first fine grids are alternately arranged along the first direction, and the second fine grids are electrically contacted with the N-type doped conductive layer; wherein in the first direction, the width of the first fine grid is smaller than that of the second fine grid, and the ratio of the width of the first fine grid to the width of the second fine grid is 0.7-0.99. The embodiment of the utility model at least can improve the performance of the back contact battery.

Description

Technical Field

[0001] This disclosure relates to the photovoltaic field, and particularly to a back-contact battery and a photovoltaic module. Background Technology

[0002] As fossil fuels are gradually depleted, solar cells are becoming increasingly widely used as a new energy alternative. A solar cell is a device that converts solar energy into electrical energy. Solar cells utilize the photovoltaic principle to generate charge carriers, which are then extracted using electrodes, thus facilitating the efficient use of electrical energy.

[0003] Solar cells include interdigitated back contact (IBC) cells. The most significant feature of back contact cells is that the PN junction and contact metal are located on the back of the cell. This avoids the shading of the metal grid electrodes on the front of the cell, maximizes the utilization of incident light, reduces optical losses, and has a higher short-circuit current.

[0004] On the surface of some back contact batteries, P-type doped conductive layers and N-type doped conductive layers are provided. Due to the high interface state density of the P-type doped conductive layer and the lattice mismatch between the fine grid and the P-type doped conductive layer, recombination problems may occur between the P-type doped conductive layer and the fine grid, which affects the performance of the back contact battery. Utility Model Content

[0005] This disclosure provides a back-contact battery and a photovoltaic module, which can at least improve the performance of the back-contact battery.

[0006] According to some embodiments of this disclosure, one aspect of this disclosure provides a back contact battery, comprising: a substrate having a first surface and a second surface disposed opposite to each other; a P-type doped conductive layer and an N-type doped conductive layer, the P-type doped conductive layer and the N-type doped conductive layer being alternately arranged on the second surface; a plurality of first fine grids, the plurality of first fine grids being spaced apart along a first direction on the second surface, the first fine grids extending along a second direction, the first fine grids being in electrical contact with the P-type doped conductive layer; a plurality of second fine grids, the plurality of second fine grids being spaced apart along the first direction on the second surface, the second fine grids also being alternately arranged with the first fine grids along the first direction, the second fine grids extending along the second direction, the second fine grids being in electrical contact with the N-type doped conductive layer; wherein, along the first direction, the width of the first fine grid is smaller than the width of the second fine grid, and the ratio of the width of the first fine grid to the width of the second fine grid is 0.7 to 0.99.

[0007] In some embodiments, the width of the first fine gate is 10 μm to 95 μm, and the width of the second fine gate is 15 μm to 100 μm.

[0008] In some embodiments, the back contact battery further includes: a plurality of first main grids, the plurality of first main grids being arranged at intervals along the second direction on the second surface, the first main grids extending along the first direction, and the first main grids being electrically connected to the first fine grids; and an auxiliary electrode, the auxiliary electrode being located at the junction of the first main grids and the first fine grids, and being electrically connected to both the first main grids and the first fine grids.

[0009] In some embodiments, along the second direction, the width of the first main gate is a first width, the length of the auxiliary electrode is a first length, and along the first direction, the width of the auxiliary electrode is a second width, the ratio of the first length to the first width is 2 to 4, and the ratio of the second width to the first width is 0.8 to 2.

[0010] In some embodiments, the first width is 40μm to 600μm, the first length is 80μm to 2400μm, and the second width is 32μm to 1200μm.

[0011] In some embodiments, the cross-sectional area of ​​the auxiliary electrode is 0.1 mm² in the direction perpendicular to the first surface and pointing towards the second surface. 2 ~2.88mm 2 .

[0012] In some embodiments, a plurality of first main gates are spaced apart on the second surface along the second direction, the first main gates extend along the first direction, the first main gates are electrically connected to the first fine gates, the first main gates include a plurality of spaced connecting portions, and a main body portion connecting adjacent connecting portions, the connecting portions being electrically connected to the first fine gates;

[0013] Along the second direction, the width of the connecting portion is greater than the width of the main body portion.

[0014] In some embodiments, along the second direction, the ratio of the width of the connecting portion to the width of the main body portion is 1.2 to 2.

[0015] In some embodiments, along the second direction, the width of the connecting portion is 48μm to 1200μm, and the width of the main body portion is 40μm to 600μm; along the first direction, the length of the connecting portion is 32μm to 1200μm.

[0016] According to some embodiments of this disclosure, another aspect of this disclosure provides a photovoltaic module, including: a battery string, formed by connecting a plurality of back-contact batteries as described in any of the above embodiments; solder ribbons for connecting adjacent back-contact batteries; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film facing away from the battery string.

[0017] The technical solution provided in this disclosure has at least the following advantages:

[0018] The back contact battery provided in this disclosure includes: a substrate having a first surface and a second surface disposed opposite to each other; a P-type doped conductive layer and an N-type doped conductive layer, the P-type doped conductive layer and the N-type doped conductive layer being alternately arranged on the second surface; a plurality of first fine grids, the plurality of first fine grids being spaced apart along a first direction on the second surface, the first fine grids extending along a second direction, the first fine grids being in electrical contact with the P-type doped conductive layer; and a plurality of second fine grids, the plurality of second fine grids being spaced apart along the first direction on the second surface, the second fine grids also being spaced apart from the first fine grids along the first direction, the second fine grids extending along the second direction, the second fine grids being in electrical contact with the N-type doped conductive layer; wherein, along the first direction, the width of the first fine grid is smaller than the width of the second fine grid, and the ratio of the width of the first fine grid to the width of the second fine grid is 0.7 to 0.99.

[0019] The ratio of the width of the first fine gate to the width of the second fine gate is 0.7 to 0.99. That is, the smaller width of the first fine gate in contact with the P-type doped conductive layer reduces the contact area between the first fine gate and the P-type doped semiconductor layer, thereby reducing recombination losses between the two layers and improving the performance of the back contact cell. Conversely, the larger width of the second fine gate in contact with the N-type doped conductive layer results in lower resistance and a larger contact area, increasing the carrier collection rate and further enhancing the performance of the back contact cell. Attached Figure Description

[0020] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this disclosure or the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1A partial cross-sectional view of a back contact battery provided in an embodiment of this disclosure;

[0022] Figure 2 A schematic diagram of a back contact battery provided in an embodiment of this disclosure;

[0023] Figure 3 This is a schematic diagram of another structure of the back contact battery provided in an embodiment of this disclosure;

[0024] Figure 4 for Figure 3 A magnified view of a portion of point A in the diagram;

[0025] Figure 5 This is a schematic diagram of another structure of the back contact battery provided in an embodiment of this disclosure;

[0026] Figure 6 for Figure 5 A magnified view of a portion of point B in the middle;

[0027] Figure 7 This is a partial cross-sectional view of a photovoltaic module provided in an embodiment of this disclosure. Detailed Implementation

[0028] As can be seen from the background technology, the performance of back contact batteries needs to be improved due to the recombination problem between the P-type doped conductive layer and the fine grid.

[0029] This disclosure provides a back-contact battery where the ratio of the width of the first fine gate to the width of the second fine gate is 0.7 to 0.99. The smaller width of the first fine gate in contact with the P-type doped conductive layer reduces the contact area between the first fine gate and the P-type doped semiconductor layer, thereby reducing recombination losses between the two layers and improving the performance of the back-contact battery. Conversely, the larger width of the second fine gate in contact with the N-type doped conductive layer results in lower resistance and a larger contact area, increasing the carrier collection rate and further enhancing the performance of the back-contact battery.

[0030] In the description of the embodiments of this disclosure, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary or secondary relationship of the indicated technical features. In the description of the embodiments of this disclosure, "a plurality of" means two or more, unless otherwise explicitly defined.

[0031] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this disclosure. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0032] In the description of the embodiments of this disclosure, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0033] In the description of the embodiments of this disclosure, the term "multiple" refers to two or more (including two), similarly, "multiple groups" refers to two or more (including two groups), and "multiple pieces" refers to two or more (including two pieces).

[0034] In the description of the embodiments of this disclosure, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this disclosure and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this disclosure.

[0035] In the description of the embodiments of this disclosure, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0036] In the accompanying drawings corresponding to the embodiments of this disclosure, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0037] In the description of embodiments of this disclosure, when a component "includes" another component, other components are not excluded unless otherwise stated, and may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly" on the other component (i.e., located on the surface of the other component with no other components between them), or another component may be present therein. Additionally, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are located therein.

[0038] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this disclosure to facilitate a better understanding of the disclosure. However, the technical solutions claimed in this disclosure can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0039] Figure 1 This is a partial cross-sectional view of a back contact battery provided in an embodiment of the present disclosure. Figure 2 This is a schematic diagram of a back contact battery provided in an embodiment of the present disclosure.

[0040] Reference Figure 1 and Figure 2The back contact battery includes: a substrate 100 having a first surface 110 and a second surface 120 disposed opposite to each other; a P-type doped conductive layer 101 and an N-type doped conductive layer 102, the P-type doped conductive layer 101 and the N-type doped conductive layer 102 being alternately arranged on the second surface 120; and a plurality of first fine grids 103, the plurality of first fine grids 103 being arranged at intervals along a first direction X on the second surface 120, the first fine grids 103 extending along a second direction Y, and the first fine grids 103 being electrically connected to the P-type doped conductive layer 101. The surface 120 has multiple second fine gates 104, which are spaced apart along the first direction X. The second fine gates 104 are also alternately arranged with the first fine gates 103 along the first direction X. The second fine gates 104 extend along the second direction Y and are in electrical contact with the N-type doped conductive layer 102. The width of the first fine gate 103 is smaller than the width of the second fine gate 104 along the first direction X, and the ratio of the width of the first fine gate 103 to the width of the second fine gate 104 is 0.7 to 0.99.

[0041] Back-contact batteries are used to absorb sunlight and convert light energy into electrical energy.

[0042] The substrate 100 is used to receive incident light and generate photogenerated carriers. In some embodiments, the substrate 100 may be a semiconductor substrate.

[0043] In some embodiments, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material may be monocrystalline, polycrystalline, amorphous, or microcrystalline (a state simultaneously possessing both monocrystalline and amorphous states is called microcrystalline). For example, silicon may be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0044] In some embodiments, the substrate 100 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium arsenide, perovskite, cadmium telluride, copper indium selenide, etc.

[0045] The substrate 100 can also be a sapphire substrate, a silicon substrate on an insulator, or a germanium substrate on an insulator.

[0046] The substrate 100 can be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type dopant element, which can be any one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate 100 is doped with a P-type dopant element, which can be any one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0047] The substrate 100 has a first surface 110 and a second surface 120 facing each other. In some embodiments, the back contact battery is a single-sided battery, in which case the first surface 110 of the substrate 100 can serve as a light-receiving surface for receiving incident light, and the second surface 120 serves as a back-lighting surface. In some embodiments, the back contact battery is a double-sided battery, in which case both the first surface 110 and the second surface 120 of the substrate 100 can serve as light-receiving surfaces and can both be used to receive incident light. It is understood that the back-lighting surface referred to in the embodiments of this application can also receive incident light, but the degree of reception of incident light is weaker than that of the light-receiving surface, and therefore it is defined as a back-lighting surface.

[0048] In some embodiments, a texturing process can be performed on at least one of the first or second surfaces of the substrate to form a texturized surface on at least one of the first or second surfaces of the substrate, thereby enhancing the absorption and utilization rate of incident light on the first and second surfaces of the substrate.

[0049] In some embodiments, the textured surface can be a pyramid textured surface. As a common textured surface, pyramid textured surface not only reduces the reflectivity of the substrate surface, but also forms a light trap, enhancing the substrate's absorption effect on incident light and improving the photoelectric conversion efficiency of the back contact battery.

[0050] Specifically, if the back-contact battery is a single-sided battery, a textured surface can be formed on the light-receiving surface of the substrate, such as a pyramidal textured surface, while the back-lighting surface of the substrate can be a polished surface, meaning the back-lighting surface of the substrate is flatter than the light-receiving surface. It should be noted that for single-sided batteries, a textured surface can also be formed on both the light-receiving and back-lighting surfaces of the substrate.

[0051] If the back-contact battery is a bi-sided battery, a textured surface can be formed on both the light-receiving and back-light-receiving surfaces of the substrate.

[0052] The P-type doped conductive layer 101 is doped with P-type elements, and the N-type doped conductive layer 102 is doped with N-type elements.

[0053] In some embodiments, if the substrate 100 is an N-type substrate, the dopant concentration in the N-type doped conductive layer 102 is greater than the dopant concentration in the substrate 100, and a high-low junction is formed between the N-type doped conductive layer 102 and the substrate 100, enhancing the carrier separation capability. In some embodiments, if the substrate 100 is a P-type substrate, the dopant concentration in the P-type doped conductive layer 101 is greater than the dopant concentration in the substrate 100, and a high-low junction is formed between the P-type doped conductive layer 101 and the substrate 100, enhancing the carrier separation capability.

[0054] The N-type doped conductive layer 102 and the P-type doped conductive layer 101 may have a gap or isolation structure to achieve automatic isolation between regions with different conductivity types. This can prevent leakage caused by the formation of a tunnel junction between the N-type doped conductive layer 102 and the P-type doped conductive layer 101 on the second surface 120, which would affect the battery efficiency.

[0055] The first fine gate 103 is in electrical contact with the P-type doped conductive layer 101, and the second fine gate 104 is in electrical contact with the N-type doped conductive layer 102, for collecting and summarizing the current of the back contact battery.

[0056] In some embodiments, the width of the first fine gate 103 is 10 μm to 95 μm, for example, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 95 μm. The width of the first fine gate 103 is within the above range. A narrower width of the first fine gate 103 can reduce the contact area between the first fine gate 103 and the P-type doped semiconductor layer, improving the recombination problem between the first fine gate 103 and the P-type doped semiconductor while ensuring the efficiency of the first fine gate 103 in collecting charge carriers, thereby improving the performance of the back contact battery.

[0057] The width of the second fine gate 104 is 15μm to 100μm, for example, 15μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 95μm, or 100μm. Within this range, a wider width of the second fine gate 104 can reduce its resistance and increase the contact area between it and the N-type doped conductive layer 102. Both of these factors improve the carrier collection rate of the second fine gate 104, thereby enhancing the performance of the back contact cell. Furthermore, keeping the width of the second fine gate within this range avoids the problem of excessive cost associated with an excessively wide second fine gate 104.

[0058] Figure 3 This is another schematic diagram of the back contact battery provided in an embodiment of this disclosure. Figure 4 for Figure 3 A magnified view of a portion of point A in the diagram.

[0059] Reference Figure 1 , Figure 3 and Figure 4In some embodiments, the back contact battery further includes: a plurality of first main grids 105, which are spaced apart along a second direction Y on a second surface 120 and extend along a first direction X, and are electrically connected to first fine grids 103; and an auxiliary electrode 107, which is located at the junction of the first main grids 105 and the first fine grids 103 and is electrically connected to both the first main grids 105 and the first fine grids 103. The auxiliary electrode 107 can increase the contact area between the first fine grids 103 and the first main grids 105, and reduce the contact resistance between the main grids and the fine grids, thereby increasing the rate at which the first main grids 105 collect charge carriers on the first fine grids 103, and thus improving the performance of the back contact battery.

[0060] The first main gate 105 is used to collect the charge carriers derived from the first fine gate 103.

[0061] In some embodiments, the back contact battery further includes a plurality of second main grids 106, a plurality of first main grids 105 arranged at intervals along the second direction Y on the second surface 120, the second main grids 106 extending along the first direction X, and the second main grids 106 being electrically connected to the second fine grids 104.

[0062] The second main gate 106 is used to collect the carriers derived from the second fine gate 104.

[0063] It is understandable that the auxiliary electrode 107 is not in direct electrical contact with the first doped conductive layer. Therefore, the setting of the auxiliary electrode 107 will not cause recombination problems between the auxiliary electrode 107 and the P-type doped conductive layer 101. Figure 4 The orthographic projection of the auxiliary electrode 107 on the first surface 110 is a rhombus, but in reality, the orthographic projection of the auxiliary electrode 107 can also be other shapes such as rectangle, square, triangle, ellipse, etc. This embodiment does not limit the shape of the orthographic projection of the auxiliary electrode 107 on the first surface 110.

[0064] In some embodiments, the auxiliary electrode 107 and the first main grid 105 are integrally formed. This configuration allows the auxiliary electrode 107 to be fabricated in the same process step as the first main grid 105, improving the fabrication efficiency of the back contact battery.

[0065] In some embodiments, along the second direction Y, the width of the first main gate 105 is a first width, and the length of the auxiliary electrode 107 is a first length. Along the first direction X, the width of the auxiliary electrode 107 is a second width. The ratio of the first length to the first width is 2 to 4, for example, 2, 2.5, 3, 3.5, or 4; the ratio of the second width to the first width is 0.8 to 2, for example, 0.8, 1, 1.4, 1.8, or 2. The length of the auxiliary electrode 107 in the first direction X is greater than its width in the first direction X. This configuration results in a larger contact area between the auxiliary electrode 107 and the first fine gate 103, and a smaller contact resistance between the auxiliary electrode 107 and the first fine gate 103, which can improve the speed at which the auxiliary electrode 107 collects charge carriers on the first fine gate 103. In addition, if the ratio of the first length to the first width and the ratio of the second width to the first width are within the above range, the speed at which the first main gate 105 collects charge carriers on the first fine gate 103 can be increased. At the same time, it can also avoid the problem of excessive material usage required to prepare the auxiliary electrode 107 due to the excessive ratio of the first length to the first width and the excessive ratio of the second width to the first width, which would lead to excessively high costs in preparing the back contact battery.

[0066] In some embodiments, the first width is 40μm to 600μm, for example, 40μm, 80μm, 100μm, 200μm, 300μm, 400μm, 500μm, or 600μm. A first width within this range can prevent the first main gate 105 from being unable to effectively collect carriers on the first fine gate 103 due to an excessively small width, and can also prevent the first main gate 105 from having an excessively large width, resulting in excessive material usage and increased production costs for the back contact battery.

[0067] The first length is 80μm to 2400μm, for example, 80μm, 100μm, 300μm, 600μm, 1000μm, 1500μm, 2000μm, 2100μm, 2200μm, 2300μm or 2400μm. The second width is 32μm to 1200μm, for example, 32μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 1000μm or 1200μm. By keeping the first length and second width within the aforementioned range, it is possible to avoid the problem that if the first length and second width are too small, it will be difficult for the first main gate 105 to increase the collection velocity of charge carriers on the first fine gate 103. At the same time, it is also possible to avoid the problem that if the first length and second width are too large, excessive material will be required to fabricate the auxiliary electrode 107, leading to excessively high costs in fabricating the back contact battery. In other words, keeping the first length and second width within the aforementioned range can improve the collection of charge carriers on the first fine gate 103 by the first main gate 105 and save costs.

[0068] In some embodiments, the cross-sectional area of ​​the auxiliary electrode 107 is 0.1 mm² in the direction perpendicular to the first surface 110 and pointing to the second surface 120. 2 ~2.88mm 2 For example, 0.1mm 2 0.5mm 2 1mm 2 1.5mm 2 2mm 2 2.5mm 2 Or 2.88mm 2 The cross-sectional area of ​​the auxiliary electrode 107 is within the above-mentioned range. This increases the speed at which the first main grid 105 collects charge carriers on the first fine grid 103, while also avoiding the problem of excessive raw material consumption for the auxiliary electrode 107 due to an excessively large cross-sectional area, which would lead to excessively high costs in the preparation of the back contact battery.

[0069] Figure 5 This is a schematic diagram of another structure of the back contact battery provided in an embodiment of this disclosure. Figure 6 for Figure 5 A magnified view of a portion of point B in the diagram.

[0070] Reference Figure 1 , Figure 5 and Figure 6 In some embodiments, multiple first main gates 105 are arranged at intervals along a second direction Y on a second surface 120. The first main gates 105 extend along a first direction X and are electrically connected to first fine gates 103. Each first main gate 105 includes multiple spaced-apart connecting portions 115 and a main body portion 125 connecting adjacent connecting portions 115. The connecting portions 115 are electrically connected to the first fine gates 103. Along the second direction Y, the width of the connecting portion 115 is greater than the width of the main body portion 125. The larger width of the connecting portion 115 increases the contact area between the first main gate 105 and the first fine gate 103, reduces the contact resistance between them, and thus increases the speed at which the first main gate 105 collects charge carriers from the first fine gate 103, thereby improving the performance of the back contact battery.

[0071] In some embodiments, along the second direction Y, the ratio of the width of the connecting portion 115 to the width of the main body portion 125 is 1.2 to 2, for example, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2. When the ratio of the width of the connecting portion 115 to the width of the main body portion 125 is within the above range, the contact resistance between the first main gate 105 and the first fine gate 103 can be reduced, increasing the speed at which the first main gate 105 collects charge carriers from the first fine gate 103. Simultaneously, it avoids the problem of excessive material required to fabricate the connecting portion 115 due to its excessive width, thus preventing excessively high costs in fabricating the back contact battery.

[0072] In some embodiments, along the second direction Y, the width of the connecting portion 115 is 48μm to 1200μm, for example 48μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 1000μm or 1200μm; along the first direction X, the length of the connecting portion 115 is 32μm to 1200μm, for example 32μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 1000μm or 1200μm. The length and width of the connecting portion 115 are positively correlated with the contact area between the connecting portion 115 and the first fine grid 103. When the length and width of the connecting portion 115 are within the above range, the contact resistance between the first main grid 105 and the first fine grid 103 can be reduced, and the speed at which the first main grid 105 collects charge carriers on the first fine grid 103 can be increased. At the same time, it can also avoid the problem of excessive material required to prepare the connecting portion 115 due to the connecting portion being too wide and too long, which would lead to excessively high cost in preparing the back contact battery.

[0073] The width of the main body 125 is 40μm to 600μm, for example, 40μm, 100μm, 200μm, 300μm, 400μm, 450μm, 500μm, 550μm, or 600μm. The width of the main body 125 is within the above range, which ensures a high carrier transport rate in the first main gate 105 and avoids the problem of excessive material required to fabricate the main body 125 due to its excessive width, thus preventing excessively high costs in fabricating the back contact battery.

[0074] Understandable Figures 1-6 The back contact battery shown is a back contact battery with a main grid. In fact, a back contact battery can also be a back contact battery without a main grid.

[0075] In the aforementioned back-contact battery, the width of the first fine gate 103, which contacts the P-type doped conductive layer 101, is set to be relatively small. This reduces the contact area between the first fine gate 103 and the P-type doped semiconductor layer, thereby reducing recombination losses between the first fine gate 103 and the P-type doped semiconductor and improving the performance of the back-contact battery. Furthermore, the width of the second fine gate 104, which contacts the N-type doped conductive layer 102, is set to be relatively large. This results in a lower resistance for the second fine gate 104 and a larger contact area between the second fine gate 104 and the N-type doped conductive layer 102, increasing the carrier collection rate of the second fine gate 104 and thus improving the performance of the back-contact battery.

[0076] This disclosure also provides a photovoltaic module, which includes a battery string consisting of multiple back-contact batteries connected as provided in any of the foregoing embodiments. The photovoltaic module is used to convert received light energy into electrical energy. It should be noted that the parts that are the same as or corresponding to those in the foregoing embodiments can be referred to the corresponding descriptions in the foregoing embodiments, and will not be repeated hereafter.

[0077] Figure 7 This is a partial cross-sectional view of a photovoltaic module provided in an embodiment of this disclosure.

[0078] Reference Figure 2 and Figure 7 The photovoltaic module includes: a cell string, a solder ribbon 11, an encapsulating film 12, and a cover plate 13. The cell string is formed by connecting back contact cells 10 provided in any of the preceding embodiments; the solder ribbon 11 is used to connect adjacent back contact cells 10; the encapsulating film 12 is used to cover the surface of the cell string; and the cover plate 13 is used to cover the surface of the encapsulating film 12 that is away from the cell string.

[0079] In some embodiments, the back contact battery 10 can be a single cell or a sliced ​​cell, where a sliced ​​cell refers to a cell formed by cutting a single cell. The back contact battery 10 is electrically connected in a single cell or in multiple slices to form multiple battery strings, which are electrically connected in series and / or in parallel.

[0080] The solder ribbon 11 is used to connect adjacent back contact cells 10 and to transfer the current collected on the back contact cells 10 connected to the solder ribbon 11 to the assembly end connected to the cell string. One end of the solder ribbon is connected to a first main grid on a back contact cell 11, and the other end is connected to a second main grid on an adjacent back contact cell 11.

[0081] In some embodiments, the encapsulating film 12 includes a first encapsulating layer and a second encapsulating layer. The first encapsulating layer covers one of the front or back sides of the back contact battery 10, and the second encapsulating layer covers the other of the front or back sides of the back contact battery 10. Specifically, at least one of the first encapsulating layer or the second encapsulating layer can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene coelastomer (POE) film, or polyethylene terephthalate (PET) film. Alternatively, at least one of the first encapsulating layer or the second encapsulating layer can also be an EP film, EPE film, or PVP film.

[0082] Among them, EP film refers to a co-extruded film composed of stacked EVA film and POE film; EPE film refers to a co-extruded film formed by sequentially stacking EVA film, POE film, and EVA film; and PVP film refers to a co-extruded film formed by stacking POE film, EVA film, and POE film. Co-extruded films can be manufactured by sequentially extruding one or more raw materials onto another pre-made film during the film processing, or by bonding different types of pre-made films together.

[0083] In some cases, the first encapsulation layer and the second encapsulation layer still have a boundary line before lamination. After lamination, the photovoltaic module no longer has the concept of a first encapsulation layer and a second encapsulation layer, that is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film.

[0084] In some embodiments, the cover plate 13 can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate facing the encapsulating film can be an uneven surface or a textured surface containing multiple raised structures, thereby increasing the utilization rate of incident light. The cover plate 13 includes a first cover plate and a second cover plate, the first cover plate being opposite to the first encapsulation layer, and the second cover plate being opposite to the second encapsulation layer.

[0085] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of this disclosure. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this disclosure; therefore, the scope of protection of this disclosure should be determined by the scope defined in the claims.

Claims

1. A back-contact battery, characterized in that, include: A substrate having a first surface and a second surface disposed opposite to each other; P-type doped conductive layers and N-type doped conductive layers are arranged alternately on the second surface; Multiple first fine gates are arranged at intervals along a first direction on the second surface, the first fine gates extend along a second direction, and the first fine gates are in electrical contact with the P-type doped conductive layer. Multiple second fine gates are spaced apart on the second surface along the first direction. The second fine gates are also alternately arranged with the first fine gates along the first direction. The second fine gates extend along the second direction and are in electrical contact with the N-type doped conductive layer. Wherein, along the first direction, the width of the first fine gate is smaller than the width of the second fine gate, and the ratio of the width of the first fine gate to the width of the second fine gate is 0.7 to 0.

99.

2. The back contact battery according to claim 1, characterized in that, The width of the first fine gate is 10μm to 95μm, and the width of the second fine gate is 15μm to 100μm.

3. The back contact battery according to claim 1 or 2, characterized in that, The back contact battery also includes: Multiple first main gates are arranged at intervals along the second direction on the second surface, the first main gates extend along the first direction, and the first main gates are electrically connected to the first fine gates; An auxiliary electrode is located at the junction of the first main gate and the first fine gate, and is electrically connected to both the first main gate and the first fine gate.

4. The back contact battery according to claim 3, characterized in that, Along the second direction, the width of the first main gate is a first width, the length of the auxiliary electrode is a first length, and along the first direction, the width of the auxiliary electrode is a second width. The ratio of the first length to the first width is 2 to 4, and the ratio of the second width to the first width is 0.8 to 2.

5. The back contact battery according to claim 4, characterized in that, The first width is 40μm to 600μm, the first length is 80μm to 2400μm, and the second width is 3200μm to 1200μm.

6. The back contact battery according to claim 3, characterized in that, In the direction perpendicular to the first surface and pointing towards the second surface, the cross-sectional area of ​​the auxiliary electrode is 0.1 mm². 2 ~2.88mm 2 .

7. The back contact battery according to claim 1 or 2, characterized in that, The back contact battery also includes: Multiple first main gates are spaced apart on the second surface along the second direction. The first main gates extend along the first direction and are electrically connected to the first fine gates. The first main gates include multiple spaced connecting portions and a main body portion connecting adjacent connecting portions. The connecting portions are electrically connected to the first fine gates. Along the second direction, the width of the connecting portion is greater than the width of the main body portion.

8. The back contact battery according to claim 7, characterized in that, Along the second direction, the ratio of the width of the connecting portion to the width of the main body portion is 1.2 to 2.

9. The back contact battery according to claim 8, characterized in that, Along the second direction, the width of the connecting portion is 48μm to 1200μm, and the width of the main body portion is 40μm to 600μm; along the first direction, the length of the connecting portion is 32μm to 1200μm.

10. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple back-contact batteries as described in any one of claims 1 to 9; Solder strips, the solder strips being used to connect adjacent back contact batteries; An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

Images