Photovoltaic module and preparation method thereof

Abstract

The invention relates to the technical field of solar cells, in particular to a photovoltaic module and a preparation method thereof. The photovoltaic module comprises a heterojunction cell, the heterojunction cell comprises two surfaces, and the two surfaces are respectively and independently provided with a plurality of rows of silver electrode points which are discretely distributed; the plurality of tin-plated solder strips are respectively and independently bonded on the two surfaces of the heterojunction cell, and the tin-plated solder strips are arranged on each row of the silver electrode points which are discretely distributed; wherein each tin-plated solder strip comprises a copper base material, and a tin-based low-temperature alloy and a conductive bonding layer are sequentially stacked on the periphery of the copper base material; and the tin-plated solder strip and the heterojunction cell are prepared into a photovoltaic module through a film laminating process. According to the photovoltaic module, the silver consumption is reduced, and good power and stability can be maintained due to the cooperation of the tin-coated solder strip and the film laminating process.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a photovoltaic module and a preparation method thereof. Background Art

[0002] Solar photovoltaic power generation is a technology that uses the photovoltaic effect of semiconductor interfaces to convert light energy into electrical energy. As the sustainable development of human economy and society places higher and higher demands on energy and environmental protection, this power generation method has received more and more attention.

[0003] Heterojunction cells (HJT cells) have multiple advantages such as high conversion efficiency and simple process structure. They also have higher conversion efficiency and higher bifaciality, which can reach 98%. They also have lower attenuation, no potential induced degradation (PID) and light induced degradation (LID). With a lower temperature coefficient, HJT cells are flexible and not prone to cracking. Due to their special structural design and the particularity of the surface transparent conductive oxide (TCO) film and amorphous silicon / microcrystalline silicon passivation process, HJT cells usually use low-temperature processing and manufacturing processes below 200°C to ensure cell efficiency and reliability. Low-temperature metallization processes usually use low-temperature silver paste, which usually uses smaller particle size, higher content silver particles and polymer resins to realize electrodes and TCO conductive films, while leading to higher production costs.

[0004] As an emerging technology route for HJT cells, busbar-free technology has attracted much attention in recent years. Busbar-free technology eliminates the busbar design of the cell and uses a thinner low-temperature alloy layer tin-coated solder ribbon to directly interconnect with the fine grid lines on the surface of the cell, thereby reducing the amount of silver used and reducing the shading area of ​​the tin-coated solder ribbon and the grid lines, thereby achieving the purpose of reducing costs and increasing efficiency. Busbar-free technology usually has multiple technical routes such as Smartwire process, lamination process, welding + dispensing process, and dispensing + welding process. At present, there is still a need to further reduce costs and increase efficiency, improve reliability, and optimize the process flow. Taking the lamination process as an example, the process flow is: using a heterojunction cell with densely arranged fine grid lines printed on the surface, the low-temperature alloy solder ribbon is pulled to the surface of the cell, and the carrier film is laid and heated and fixed to form a cell string. After stacking, lamination, framing and curing, a photovoltaic module is formed. This technical route still requires a high silver consumption, and the production cost is still high.

[0005] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the invention

[0006] The embodiments of the present application provide a photovoltaic module and a method for preparing the same to solve or alleviate one or more of the technical problems mentioned above.

[0007] A first aspect of an embodiment of the present application provides a photovoltaic module.

[0008] The photovoltaic module includes: A heterojunction battery, the heterojunction battery comprising two surfaces, the two surfaces being independently provided with multiple rows of discretely distributed silver electrode points; Tin-coated solder strips, wherein a plurality of the tin-coated solder strips are independently bonded to two surfaces of the heterojunction battery, and each row of discretely distributed silver electrode points is provided with a tin-coated solder strip; Wherein, the tin-coated solder strips all include a copper substrate, and a tin-based low-temperature alloy and a conductive adhesive layer are sequentially stacked on the periphery of the copper substrate; The tin-coated solder strip and the heterojunction cell are prepared into a photovoltaic module through a film lamination process.

[0009] A second aspect of an embodiment of the present application provides a method for preparing a photovoltaic module.

[0010] The method for preparing the photovoltaic module comprises the following operations: Provide tin-coated solder ribbon and heterojunction cells; The heterojunction battery comprises two surfaces, and a plurality of rows of discretely distributed silver electrode points are independently arranged on the two surfaces; the tin-coated solder strip comprises a copper substrate, and a tin-based low-temperature alloy and a conductive adhesive layer are sequentially stacked on the periphery of the copper substrate; Independently bonding a plurality of the tin-coated solder strips on two surfaces of the heterojunction battery; Wherein, on the two surfaces, each row of discretely distributed silver electrode points is provided with a tin-coated solder strip; By using a lamination process, a plurality of cells including the heterojunction cells bonded with a plurality of the tin-coated solder ribbons are formed into a cell string, and then laminated to obtain a photovoltaic module.

[0011] The above technical solution adopted in the embodiment of the present application may have the following advantages: The photovoltaic module of the present application only retains silver electrode points on the heterojunction battery, which can greatly reduce the amount of silver used, while reducing the optical shielding of the battery surface by the fine grid lines and the adverse effects of chemical substances on the battery during the low-temperature sintering process of large-area fine grid line silver paste; and the silver electrode points arranged in rows can be interconnected with the tin-coated solder strips, and the conductive adhesive layer of the tin-coated solder strips plays the two roles of flexible bonding with the TCO and / or the silver electrode points and interconnection and conduction; after the film lamination process, the tin-based low-temperature alloy and the conductive adhesive layer melt to form a conductive channel with the TCO and / or the silver electrode points and the heterojunction battery. While reducing the amount of silver used, the photovoltaic module has good power, reliability and stability due to the cooperation of the tin-coated solder strips and the film lamination process. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0013] FIG. 1 is a schematic diagram of the structure of a heterojunction battery with silver electrode points provided in an embodiment of the present application, wherein FIG. 1 (a) is a top view and FIG. 1 (b) is a front view; Figure 2 It is a schematic diagram of the structure of a heterojunction battery with a tin-coated solder strip provided in an embodiment of the present application; Figure 3 is a schematic diagram of the structure of a laminate provided in an embodiment of the present application; Figure 4 It is a schematic diagram of the structure of the tin-coated solder strip provided in an embodiment of the present application.

[0014] Description of reference numerals: DETAILED DESCRIPTION Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. Wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0015] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. When the second element, component, region, layer or part is discussed, it does not indicate that the present application necessarily has the first element, component, region, layer or part.

[0016] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0017] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0018] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed in the present application should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for broadly including quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0019] The embodiment of the present application provides a photovoltaic module and a technical solution for its preparation method. Based on this, the problem of high silver consumption is solved. See below for details.

[0020] Hereinafter, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. It should be noted that these exemplary embodiments can be implemented in many different forms and should not be construed as being limited to the embodiments described herein.

[0021] In a first aspect, an embodiment of the present application provides a photovoltaic module, which includes a heterojunction cell 1 and a plurality of tin-coated solder strips 3 .

[0022] As shown in FIG1 , in some embodiments, a heterojunction battery 1 includes two surfaces, and a plurality of rows of discretely distributed silver electrode points 2 are independently provided on the two surfaces, and each row of discretely distributed silver electrode points 2 is shown in the dotted box in FIG1 (a); thus, the use of discretely distributed silver electrode points can reduce the amount of silver used, and can also be used as test electrode points in the battery cell preparation stage to test the battery cell power, thereby facilitating the production of battery cells with the same power into battery strings.

[0023] In some embodiments, the heterojunction cell 1 comprises a monocrystalline silicon wafer; one side of the monocrystalline silicon wafer is provided with a first intrinsic layer, a n + The other side of the single crystal silicon wafer is provided with a second intrinsic layer, a p-doped layer and a first transparent conductive oxide film in sequence. + doping layer and a second transparent conductive oxide film.

[0024] It can be understood that the heterojunction cell 1 includes two transparent conductive oxide films (TCO) located on both sides thereof, namely, a first transparent conductive oxide film and a second transparent conductive oxide film.

[0025] Furthermore, participate Figure 2 , on the two surfaces of the heterojunction battery 1, each row of discretely distributed silver electrode points 2 is arranged in parallel; in the second direction of the two surfaces, 7 to 16 rows of discretely distributed silver electrode points are arranged every 10 cm in length; wherein the second direction is perpendicular to the first direction, and the first direction is the direction in which each row of discretely distributed silver electrode points 2 is located, that is, Figure 2 The middle arrow indicates the direction. Thus, while reducing the amount of silver used, sufficient silver electrode points 2 are retained to alleviate or even avoid the problem of difficulty in extracting carriers due to excessive contact resistance of other materials.

[0026] Optionally, when the heterojunction battery 1 is rectangular, each row of discretely distributed silver electrode points may be arranged parallel to two sides of the heterojunction battery 1 .

[0027] The embodiment of the present application does not limit the shape of the silver electrode point 2. The width of the silver electrode point 2 can be the same as that of a conventional fine grid to collect carriers. Optionally, as shown in FIG1 , the shape of the silver electrode point 2 is rectangular and the size can be 0.5 mm×1 mm. Optionally, the shape of the silver electrode point 2 can also be circular and the area can be 1 mm 2 .

[0028] like Figure 2As shown, in some embodiments, in the heterojunction battery 1, a plurality of tin-coated solder strips 3 are independently bonded to two surfaces of the heterojunction battery 1, and a tin-coated solder strip 3 is provided on each row of discretely distributed silver electrode points 1.

[0029] In some embodiments, in the heterojunction battery 1, multiple tin-coated solder strips 3 are arranged in parallel on both surfaces thereof; and 7 to 33 tin-coated solder strips are arranged in a length of 10 cm in a direction perpendicular to the tin-coated solder strips 3. Thus, the tin-coated solder strips are used to extract or transport carriers.

[0030] Alternatively, if Figure 2 As shown, each row of discretely distributed silver electrode points 1 is provided with a tin-coated solder strip 3, and a portion of the tin-coated solder strip 3 is directly bonded to the TCO of the heterojunction battery 1. At this time, in the direction perpendicular to the tin-coated solder strip 3, the arrangement density of the tin-coated solder strip 3 per 10 cm length is greater than the arrangement density of the discretely distributed silver electrode points 1, a portion of the tin-coated solder strip 3 is directly in contact with the TCO for carrier extraction and transportation, and another portion of the tin-coated solder strip 3 is directly in contact with the silver electrode point 1, and the silver electrode point 1 is used to transfer the extracted carriers to the tin-coated solder strip 3, and the tin-coated solder strip 3 is used for carrier transportation.

[0031] Optionally, the tin-coated solder strips 3 are all bonded to the TCO of the heterojunction battery 1 through the discretely distributed silver electrode points 1 arranged in rows. At this time, in the direction perpendicular to the tin-coated solder strips 3, the number of tin-coated solder strips 3 is equal to the number of rows of the discretely distributed silver electrode points 1, and the silver electrode points 1 are used to transfer the extracted carriers to the tin-coated solder strips 3, and the tin-coated solder strips 3 are used for carrier transportation.

[0032] In some embodiments, in the heterojunction battery 1, the tin-coated solder strip 3 and the heterojunction battery 1 are prepared into a photovoltaic module through a film lamination process. Thus, during the lamination process, the tin-coated solder strip 3 can be interconnected with the TCO and / or the silver electrode point to achieve electrical connection between the tin-coated solder strip 3 and the TCO and / or the silver electrode point.

[0033] Furthermore, the plurality of tin-coated solder strips 3 each include a copper substrate 3-1, and a tin-based low-temperature alloy 3-2 and a conductive adhesive layer 3-3 are sequentially laminated on the periphery of the copper substrate 3-1. Thus, the conductive adhesive layer 3-3 can not only play the role of bonding and fixing the tin-coated solder strip 3, but also the tin-based low-temperature alloy 3-2 will melt under heat during the lamination process, and form a connection with the conductive material in the conductive adhesive layer 3-3, forming an integral conductive channel on the TCO based on ohmic contact and tunneling effect.

[0034] It is worth noting that tin-based low-temperature alloys refer to alloys that contain a high proportion of tin and add other metal elements to improve their performance. The melting point of this type of alloy is usually lower than that of pure tin (231.9°C), and it has better processability and performance in low-temperature environments.

[0035] Optionally, the width of the orthographic projection of the tin-coated solder strip 3 on the two surfaces of the heterojunction battery is independently 0.05 mm to 0.3 mm, for example, 0.05 mm, 0.1 mm, 0.15 mm, 0.20 mm, 0.22 mm, 0.27 mm, 0.3 mm, etc. Thus, under the premise of ensuring the carrier collection capacity, the tin-coated solder strip 3 is prevented from being too wide to block the surface area of ​​the battery cell, and the welding stress is also prevented from being too large, and the thickness of the encapsulation film needs to be increased to release the mechanical stress.

[0036] Optionally, attend Figure 4 , the shape of the tin-coated solder strip 3 can be cylindrical. Further, the diameter of the copper substrate 3-1 is 0.05mm-0.27mm, the thickness of the tin-based low-temperature alloy 3-2 is 0.5μm-10μm, and the thickness of the conductive adhesive layer 3-3 is 2μm-20μm. For example, the diameter of the copper substrate 3-1 is 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.27mm, etc.; the thickness of the tin-based low-temperature alloy 3-2 is 0.5μm, 1μm, 2.5μm, 5.5μm, 10μm, etc.; the thickness of the conductive adhesive layer 3-3 is 2μm, 10μm, 12μm, 20μm, etc. Thus, the conductive performance is optimized, and the adverse effects of the insulating material in the conductive layer are weakened while ensuring the bonding force.

[0037] Preferably, the melting point of the tin-based low temperature alloy is 120°C to 165°C, such as 120°C, 130°C, 150°C, 165°C, etc. Therefore, the lamination conditions are relatively broad, and the electrical connection between the tin-coated solder strip 3 and the TCO can be achieved by providing a lamination temperature higher than the melting point.

[0038] Exemplarily, the tin-based low temperature alloy includes Sn 43 Pb 43 Bi 14 Alloy, Sn 37 Pb 42 Bi 21 Alloy, Sn 43 Pb 34 Bi 23 Alloy, Sn 32 Pb 42 Bi 26 Alloy and Sn 52 Bi 48 At least one of the alloys.

[0039] In some embodiments, the conductive adhesive layer contains more than 60 wt % of conductive particles, preferably 80 wt % to 90 wt % of conductive particles. Thus, by containing a large amount of conductive particles in the conductive adhesive layer, the contact resistance with the TCO or silver electrode point is optimized.

[0040] Optionally, the conductive particles may be at least one of silver powder particles and silver-coated copper particles.

[0041] A second aspect of the present application provides a method for preparing a photovoltaic module. The method for preparing a photovoltaic module comprises the following steps: S1, providing a tin-coated solder strip 3 and a heterojunction battery 1; The heterojunction battery 1 includes two surfaces, and multiple rows of discretely distributed silver electrode points 2 are independently arranged on the two surfaces; the tin-coated solder strip 3 includes a copper substrate 3-1, and a tin-based low-temperature alloy 3-2 and a conductive adhesive layer 3-3 are sequentially stacked on the periphery of the copper substrate 3-1; Preferably, the melting point of the tin-based low-temperature alloy is 120°C to 165°C.

[0042] Exemplarily, the tin-based low temperature alloy includes Sn 43 Pb 43 Bi 14 Alloy, Sn 37 Pb 42 Bi 21 Alloy, Sn 43 Pb 34 Bi 23 Alloy, Sn 32 Pb 42 Bi 26 Alloy and Sn 52 Bi 48 At least one of the alloys.

[0043] In some embodiments, the conductive adhesive layer contains more than 60wt% of conductive particles, preferably 80wt% to 90wt% of conductive particles. Optionally, the conductive particles can be at least one of silver powder particles and silver-coated copper particles. Thus, by containing a large amount of conductive particles in the conductive adhesive layer, the contact resistance with the TCO or silver electrode point is optimized.

[0044] In some specific embodiments, on the two surfaces, each row of discretely distributed silver electrode points is arranged in parallel; in the second direction of the two surfaces, 7 to 16 rows of discretely distributed silver electrode points are arranged in a length of every 10 cm; wherein the second direction is perpendicular to the first direction, and the first direction is the direction of each row of discretely distributed silver electrode points.

[0045] S2, bonding a plurality of tin-coated solder strips 3 independently on two surfaces of the heterojunction battery 1; Wherein, on the two surfaces, each row of discretely distributed silver electrode points 2 is provided with a tin-coated solder strip 3; Optionally, the number of rows of discretely distributed silver electrode points 2 is equal to the number of tin-coated solder strips 3 .

[0046] Optionally, the number of tin-coated solder strips 3 is greater than the number of rows of discretely distributed silver electrode points 2 .

[0047] In some specific embodiments, on the two surfaces, a plurality of tin-coated solder strips are arranged in parallel; in a direction perpendicular to the tin-coated solder strips, 7 to 33 tin-coated solder strips are arranged in a length of every 10 cm.

[0048] Furthermore, the width of the orthographic projection of the tin-coated solder strip 3 on the surface of the heterojunction battery is 0.05 mm to 0.3 mm, for example, it can be 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.22 mm, 0.27 mm, 0.3 mm, etc.

[0049] S3, using a lamination process, forming a battery string with a plurality of cells including the heterojunction cells 1 bonded with a plurality of the tin-coated solder strips 3, and then laminating to obtain a photovoltaic module. Thus, during the lamination process, the tin-coated solder strips 3 are electrically connected to the TCO via the silver electrode on the TCO, or the tin-coated solder strips 3 are directly electrically connected to the TCO.

[0050] In some specific embodiments, the use of a coating process to form a battery string from a plurality of heterojunction batteries bonded with a plurality of tin-coated solder ribbons comprises: connecting the heterojunction batteries in series with adjacent batteries through each other's solder ribbons, and then laying carrier films (a first carrier film 4 and a second carrier film 7) on both surfaces of all the batteries, respectively, and heating and fixing them to form a battery string.

[0051] It is worth noting that all or part of the batteries in the battery string may adopt the heterojunction battery.

[0052] Optionally, the first carrier film 4 and the second carrier film 7 are usually thin packaging adhesive films with relatively low fluidity, usually with a grammage of 50 g / m 2 ~150g / m 2 , currently the most commonly used is 90g / m 2 , 100g / m 2 The material can be ethylene-vinyl acetate copolymer film (EVA) and polyolefin film (POE).

[0053] In some specific embodiments, the subsequent lamination to obtain a photovoltaic module includes: laminating a first transparent adhesive film 5 and a first glass plate 6 in sequence on one side of the battery string, laminating a second transparent adhesive film 8 on the other side of the battery string, and laminating a second glass plate 9 or a back plate on the side of the second transparent adhesive film 8 away from the battery string; laminating at a pressure of -50Kpa to 0Kpa and a temperature of 135℃ to 170℃ to obtain the photovoltaic module. For example, the pressure may be -50Kpa, -30Kpa, -10Kpa, 0Kpa; the temperature may be 135℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, etc.

[0054] A third aspect of an embodiment of the present application provides a photovoltaic module, which is prepared according to the preparation method of the second aspect of an embodiment of the present application.

[0055] The following will conduct performance tests on a photovoltaic module preparation method provided in an embodiment of the present application and related comparative examples.

[0056] [Example 1] The specific preparation process is: Step 1: providing a tin-coated solder strip 3 and a heterojunction battery 1; The heterojunction battery 1 is rectangular, and the size of the heterojunction battery 1 is 210 mm×210 mm; the heterojunction battery 1 includes two surfaces, and 24 rows of discretely distributed silver electrode points 2 are evenly distributed on the two surfaces; The tin-coated solder strip 3 comprises a copper substrate 3-1 with a diameter of 0.1 mm, and a tin-based low-temperature alloy 3-2 with a thickness of 1 μm and a conductive adhesive layer 3-3 with a thickness of 5 μm are sequentially stacked on the periphery of the copper substrate 3-1; Specifically, the tin-based low temperature alloy 3-2 uses Sn 32 Pb 42 Bi 26 Alloy; The conductive bonding layer is made of a mixture of acrylic resin and silver powder particles in a mass ratio of 1:6. The acrylic resin uses an acrylic ester structural adhesive of the Loctite brand under the Henkel Group, the specific model is Loctite AA 3556; Step 2: independently bonding 24 tin-coated solder strips 3 on two surfaces of the heterojunction battery 1; Among them, on the two surfaces, each row of discretely distributed silver electrode points 2 is provided with a tin-coated solder strip 3; at this time, the number of tin-coated solder strips 3 is equal to the number of rows of discretely distributed silver electrode points 2.

[0057] Step 3: Obtain 13 heterojunction cells 1 of step 2, and lay 24 tin-coated solder strips 3 on the front and back of the heterojunction cells 1, respectively, with the tin-coated solder strips 3 on the front and back of adjacent heterojunction cells 1 overlapping each other; then lay carrier films (first carrier film 4 and second carrier film 7) on both surfaces of all heterojunction cells 1, and heat at 90°C for 1500 milliseconds to form a cell string. On one side of the cell string, laminate the first transparent adhesive film 5 and the first glass plate 6 in sequence, on the other side of the cell string, laminate the second transparent adhesive film 8, and on the side of the second transparent adhesive film 8 away from the cell string, laminate the second glass plate 9; perform lamination at a pressure of -30Kp and a temperature of 155°C to obtain a laminate; The first carrier film 4 and the second carrier film 7 have a thickness of 0.15 mm and a density of 0.96 g / cm 3 , weight 100g / m 2 EVA film with pattern.

[0058] Step 4: Install the frame and photovoltaic junction box on the laminate, and after curing, obtain the photovoltaic module.

[0059] [Example 2] The rest is the same as Example 1, except that: In step 1, 14 rows of discretely distributed silver electrode points 2 are arranged on the heterojunction battery 1.

[0060] [Example 3] The rest is the same as Example 1, except that: In step 1, 32 rows of discretely distributed silver electrode points 2 are arranged on the heterojunction battery 1.

[0061] [Example 4] The rest is the same as Example 1, except that: In step 1, more than 10 rows of discretely distributed silver electrode points 2 are set on the heterojunction battery 1.

[0062] [Example 5] The rest is the same as Example 1, except that: In step 2, the number of tin-coated solder strips 3 is greater than the number of rows of discretely distributed silver electrode points 2, and 36 tin-coated solder strips 3 are used on each surface and evenly distributed on the two surfaces of the heterojunction battery.

[0063] [Comparative Example 1] The rest is the same as Example 1, except that: The tin-coated solder strip 3 used in step 1 does not contain a conductive adhesive layer, that is, the tin-coated solder strip 3 includes a copper substrate 3-1 with a diameter of 0.1 mm, and a tin-based low-temperature alloy 3-2 with a thickness of 1 μm is sequentially stacked on the periphery of the copper substrate 3-1.

[0064] [Comparative Example 2] The rest is the same as Example 1, except that: In step 1, no silver electrode points 2 are provided on the two surfaces of the heterojunction battery 1.

[0065] [Comparative Example 3] The specific preparation process is: Step 1: providing a heterojunction battery 1; The heterojunction battery 1 is rectangular, and the size of the heterojunction battery 1 is 210 mm×210 mm; 186 silver fine grid lines are screen-printed; Step 2: 24 tin-coated solder strips 3 are bonded independently on two surfaces of the heterojunction battery 1 and interconnected; Wherein, on the two surfaces, the tin-coated solder strips 3 are arranged perpendicular to the direction of the fine grid; Step 3: Obtain 13 heterojunction cells 1 of step 2, and lay 24 tin-coated solder strips 3 on the front and back of the heterojunction cells 1, respectively, with the tin-coated solder strips 3 on the front and back of adjacent heterojunction cells 1 overlapping each other; then lay carrier films (first carrier film 4 and second carrier film 7) on both surfaces of all heterojunction cells 1, and heat at 90°C for 1500 milliseconds to form a cell string. On one side of the cell string, laminate the first transparent adhesive film 5 and the first glass plate 6 in sequence, on the other side of the cell string, laminate the second transparent adhesive film 8, and on the side of the second transparent adhesive film 8 away from the cell string, laminate the second glass plate 9; perform lamination at a pressure of -30Kp and a temperature of 155°C to obtain a laminate.

[0066] The first carrier film 4 and the second carrier film 7 have a thickness of 0.15 mm and a density of 0.96 g / cm 3 , weight 100g / m 2 EVA film with pattern.

[0067] Step 4: Install a frame and a photovoltaic junction box on the laminate, and after curing, a photovoltaic module is obtained.

[0068]

Test example

[0069] The cell efficiency is obtained by testing the IV volt-ampere characteristics of the cell in step 2 using a solar cell simulator under STC conditions.

[0070] The module power is obtained by performing an IV volt-ampere characteristic test on the photovoltaic module in step 4 using a photovoltaic module simulator under STC conditions.

[0071] DH 2000Power attenuation, refer to IEC61215-2, test for 2000 hours in a high temperature and high humidity environment aging chamber at 85℃ and 85%RH, compare the output power of the photovoltaic modules before and after aging to obtain the test data.

[0072] TC 400 Power attenuation, refer to IEC61215-2, use a high and low temperature cycle environment aging chamber to test 400 cycles at -40℃ ~ 85℃, compare the output power of the photovoltaic modules before and after aging, and obtain the test data.

[0073] TC 50 +HF 30 Power attenuation, refer to IEC61215-2, test 50 cycles in a high and low temperature cycle environmental aging chamber at -40℃ ~ 85℃, then test 30 cycles in a high and low temperature cycle environmental aging chamber at -40℃ ~ 85℃, 85%RH, compare the output power of the photovoltaic modules before and after aging, and obtain the test data.

[0074] Table 1:

[0075] It can be seen from Table 1 above that while the battery efficiency and component power of Examples 1 to 5 remain at a high level, the power attenuation remains at a low level. Compared with Comparative Example 3, Examples 1 to 5 maintain the same level or even higher performance than Comparative Example 3. Compared with Examples 1 to 3, the silver electrode points of Example 4 are greatly reduced. It can be seen that the battery efficiency and component power are reduced to varying degrees. This may be due to the fact that there are too few silver electrode points, which is not conducive to carrier extraction and transportation. Compared with Example 1, Example 5 increases the number of tin-coated solder strips 3, which reduces the interconnection resistance of the battery to a certain extent, but also leads to an increase in the shading area of ​​the solar cell surface, resulting in a slight decrease in the overall efficiency of the photovoltaic module. Since Example 5 increases the number of tin-coated solder strips at non-electrode points, the connection points at non-electrode points (tin-coated solder strips connected to TCO film) are slightly worse than the electrode connection points (tin-coated solder strips connected to silver electrodes) due to their slightly poor firmness, which will show a slightly higher power attenuation during reliability testing. Compared with Example 1, the tin-coated solder strip 3 used in Comparative Example 1 does not contain a conductive adhesive layer. It can be seen that the battery efficiency and component power remain at a good level, but the attenuation is greatly increased. This is because the tin-coated solder strip lacks a conductive adhesive layer and cannot play a more effective flexible interconnection effect. In addition, the electrode connection point has relatively poor resistance to temperature shock and is more prone to offset and dislocation during the connection of the battery cell. Compared with Example 1, Comparative Example 2 does not set a silver electrode point. Since the battery efficiency needs to be calibrated using a silver electrode point, Comparative Example 2 cannot be measured, and the component power is reduced by three percentage points compared with Example 1. This shows that the contact resistance increases when the tin-coated solder strip 3 is in direct contact with the TCO, which is not conducive to the collection of carriers. Comparative Example 3 is a conventional 0BB battery with better performance, but a large amount of silver is used.

[0076] It should be noted that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0077] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0078] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0079] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A photovoltaic module, characterized in that: include: A heterojunction battery, the heterojunction battery comprising two surfaces, the two surfaces being independently provided with multiple rows of discretely distributed silver electrode points; Tin-coated solder strips, wherein a plurality of the tin-coated solder strips are independently bonded to two surfaces of the heterojunction battery, and each row of discretely distributed silver electrode points is provided with a tin-coated solder strip; Wherein, the tin-coated solder strips all include a copper substrate, and a tin-based low-temperature alloy and a conductive adhesive layer are sequentially stacked on the periphery of the copper substrate; The tin-coated solder strip and the heterojunction cell are prepared into a photovoltaic module through a film lamination process.

2. The photovoltaic module according to claim 1, characterized in that: On the two surfaces, each row of discretely distributed silver electrode points is arranged in parallel; In the second direction of the two surfaces, 7 to 16 rows of discretely distributed silver electrode points are arranged in a length of every 10 cm; The second direction is perpendicular to the first direction, and the first direction is the direction of each row of discretely distributed silver electrode points.

3. The photovoltaic module according to claim 1, characterized in that: On the two surfaces, a plurality of tin-coated solder strips are arranged in parallel; In a direction perpendicular to the tin-coated solder strips, 7 to 33 tin-coated solder strips are arranged in a length of 10 cm.

4. The photovoltaic module according to claim 2 or 3, characterized in that: The orthographic projection widths of the tin-coated solder strip on the two surfaces of the heterojunction battery are independently 0.05 mm to 0.3 mm.

5. The photovoltaic module according to claim 1, characterized in that: The melting point of the tin-based low-temperature alloy is 120°C to 165°C.

6. The photovoltaic module according to claim 5, characterized in that: The tin-based low temperature alloy includes Sn 43 Pb 43 Bi 14 Alloy, Sn 37 Pb 42 Bi 21 alloy 、 Sn 43 Pb 34 Bi 23 Alloy, Sn 32 Pb 42 Bi 26 Alloy, Sn 52 Bi 48 At least one of the alloys.

7. The photovoltaic module according to claim 1, characterized in that: The heterojunction cell comprises a single crystal silicon wafer; The first intrinsic layer, n + The other side of the single crystal silicon wafer is provided with a second intrinsic layer, a p-doped layer and a first transparent conductive oxide film in sequence. + doping layer and a second transparent conductive oxide film.

8. A method for preparing a photovoltaic module, characterized in that: The following operations are included: Provide tin-coated solder ribbon and heterojunction cells; The heterojunction battery comprises two surfaces, and a plurality of rows of discretely distributed silver electrode points are independently arranged on the two surfaces; the tin-coated solder strip comprises a copper substrate, and a tin-based low-temperature alloy and a conductive adhesive layer are sequentially stacked on the periphery of the copper substrate; Independently bonding a plurality of the tin-coated solder strips on two surfaces of the heterojunction battery; Wherein, on the two surfaces, each row of discretely distributed silver electrode points is provided with a tin-coated solder strip; By using a lamination process, a plurality of cells including the heterojunction cells bonded with a plurality of the tin-coated solder ribbons are formed into a cell string, and then laminated to obtain a photovoltaic module.

9. The method for preparing a photovoltaic module according to claim 8, characterized in that: On the two surfaces, each row of discretely distributed silver electrode points is arranged in parallel; In the second direction of the two surfaces, 7 to 16 rows of discretely distributed silver electrode points are arranged in a length of every 10 cm; The second direction is perpendicular to the first direction, and the first direction is the direction of each row of discretely distributed silver electrode points.

10. The method for preparing a photovoltaic module according to claim 8, characterized in that: On the two surfaces, a plurality of tin-coated solder strips are arranged in parallel; In a direction perpendicular to the tin-coated solder strips, 7 to 33 tin-coated solder strips are arranged in a length of 10 cm.

11. The method for preparing a photovoltaic module according to claim 8, characterized in that: The orthographic projection widths of the tin-coated solder strip on the two surfaces of the heterojunction battery are independently 0.05 mm to 0.3 mm.

12. The method for preparing a photovoltaic module according to claim 8, characterized in that: The melting point of the tin-based low-temperature alloy is 120°C to 165°C.

13. The method for preparing a photovoltaic module according to claim 12, characterized in that: In parts by weight, the tin-based low temperature alloy comprises Sn 43 Pb 43 Bi 14 Alloy, Sn 37 Pb 42 Bi 21 alloy 、 Sn 43 Pb 34 Bi 23 Alloy, Sn 32 Pb 42 Bi 26 Alloy, Sn 52 Bi 48 At least one of the alloys.

14. The method for preparing a photovoltaic module according to claim 8, characterized in that: The method of forming a battery string from a plurality of batteries of the heterojunction battery bonded with a plurality of tin-coated solder strips by using a laminating process comprises: The heterojunction battery and adjacent batteries are connected in series through each other's welding strips, and then carrier films are laid on the two surfaces of all batteries respectively, and heated and fixed to form a battery string.

15. The method for preparing a photovoltaic module according to claim 8, characterized in that: The photovoltaic module is then laminated to obtain the photovoltaic module comprising: A first transparent adhesive film and a first glass plate are sequentially laminated on one side of the battery string, a second transparent adhesive film is laminated on the other side of the battery string, and a second glass plate or a back plate is laminated on a side of the second transparent adhesive film away from the battery string; The photovoltaic module is laminated at a pressure of -50Kpa to 0Kpa and a temperature of 135°C to 170°C to obtain the photovoltaic module.

16. A photovoltaic module, characterized in that: The photovoltaic module is prepared according to the method for preparing the photovoltaic module according to any one of claims 8 to 15.

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