A method for preparing a photovoltaic module and a photovoltaic module

Abstract

The present application discloses a preparation method of a photovoltaic module and a photovoltaic module. The preparation method includes: forming a soldering aid layer on the surface of a battery chip, and connecting the soldering aid layer to an electrode on the surface of the battery chip; heating the soldering aid layer at a first preset temperature, where the first preset temperature is lower than the melting point of the soldering aid layer; heating the soldering aid layer at a second preset temperature to weld and fix the soldering aid layer to the electrode, where the second preset temperature is greater than or equal to the melting point of the soldering aid layer. In the present application, by adopting a segmented heating method, the soldering aid layer can be uniformly heated, the soldering aid material in the soldering aid layer can be gradually melted and fully combined with the electrode, which helps to improve the connection strength between the soldering aid layer and the electrode. At the same time, the density of the soldering aid layer after curing can also be improved, and the surface of the soldering aid layer after curing is more round and plump, which helps to improve the subsequent soldering effect.

Description

Technical Field

[0001] This application belongs to the field of photovoltaic technology, and particularly relates to a preparation method of a photovoltaic module and a photovoltaic module. Background Art

[0002] In a crystalline silicon back contact cell (BC), the PN junction and electrodes are both located on the back of the cell. Since there are no electrodes on its front side, it has the characteristics of low shading loss and beautiful appearance, and has great development potential. However, due to the relatively complex structure of the BC cell compared to the heterojunction cell and the large number of production processes, it faces challenges in the mass production route.

[0003] Currently, a relatively common way to interconnect cell wafers in BC modules is the method of solder paste printing and soldering with solder strips. The solder paste is printed onto the corresponding welding points on the surface of the cell wafer through a printing stencil, and after drying and curing in a drying furnace, raised solder paste dots are formed. Then, the solder strips are welded to the solder paste dots to achieve the electrical connection of multiple cell wafers. However, the solder paste dots dried by the existing drying process have defects such as surface collapse and a large amount of solder splash, which affect the subsequent welding effect. Summary of the Invention

[0004] This application aims to provide a preparation method of a photovoltaic module and a photovoltaic module, which can solve the problem that the solder paste dots dried by the existing drying process have defects such as surface collapse and a large amount of solder splash, affecting the subsequent welding effect.

[0005] To solve the above technical problems, this application is implemented as follows:

[0006] In a first aspect, an embodiment of this application provides a preparation method of a photovoltaic module, including:

[0007] Form a soldering aid layer on the surface of the cell wafer, and connect the soldering aid layer to the electrodes on the surface of the cell wafer;

[0008] Heat the soldering aid layer at a first preset temperature, where the first preset temperature is less than the melting point of the soldering aid layer;

[0009] Heat the soldering aid layer at a second preset temperature to weld and fix the soldering aid layer to the electrodes, where the second preset temperature is greater than or equal to the melting point of the soldering aid layer.

[0010] Optionally, before heating the soldering aid layer at the first preset temperature, it further includes:

[0011] Preheat the soldering aid layer at a third preset temperature, where the third preset temperature is less than or equal to the first preset temperature.

[0012] Optionally, the third preset temperature is from T0 - 50°C to T0 - 20°C, where T0 is the melting point of the solder layer, and the preheating time is 20s to 30s.

[0013] Optionally, after heating the solder layer at the second preset temperature, the following steps are further included:

[0014] Cool the solder layer to a fourth preset temperature, with the cooling time being greater than or equal to 35s, and the fourth preset temperature being in the range of 30°C to 50°C.

[0015] Optionally, the solder layer after cooling is hemispherical or quasi - hemispherical.

[0016] Optionally, after forming the solder layer on the surface of the solar cell and before heating the solder layer at the first preset temperature, the following steps are further included:

[0017] Place the solar cell in the heating chamber of the heating device and introduce a protective gas into the heating chamber.

[0018] Optionally, heating the solder layer at the first preset temperature includes:

[0019] At the first preset temperature, heat the solder layer for a first preset time, where the first preset time is 40s to 50s, and the first preset temperature is in the range of T0 - 50°C to T0 - 20°C, and T0 is the melting point of the solder layer.

[0020] Optionally, heating the solder layer at the second preset temperature includes:

[0021] At the second preset temperature, heat the solder layer for a second preset time, where the second preset time is 22s to 26s, and the second preset temperature is in the range of T0 to T0 + 50°C, and T0 is the melting point of the solder layer.

[0022] In a second aspect, an embodiment of the present application provides a photovoltaic module, including: a plurality of solar cells and interconnectors; a plurality of electrodes are provided on the surface of the solar cells, the electrodes have connection parts, at least part of the connection parts are covered with a solder layer, and at least part of the interconnectors are embedded in the solder layer; sputtering points are distributed around the solder layer, and the distance between the sputtering points and the solder layer is less than or equal to 1.5mm.

[0023] Optionally, along the direction perpendicular to the surface of the solar cell, the orthographic projection area of the sputtering point is less than or equal to 0.03mm 2 。

[0024] Optionally, the welding strength between the interconnector and the solder layer is 1.5MPa to 4MPa.

[0025] In an embodiment of the present application, by forming a soldering aid layer on the surface of a battery cell and adopting a segmented heating method, compared with rapidly heating to the melting point in the prior art, before drying at a temperature higher than the melting point (i.e., heating at a second preset temperature) in the present application, a first preset temperature heating stage with a slow temperature rise is set, which can avoid the serious problem of splashing of the soldering aid layer material caused by directly heating to the melting point temperature rapidly. Thus, the probability of solder explosion in the soldering aid layer can be reduced, the problem of short circuit of the battery cell caused by the sputtering points of the soldering aid layer can be avoided, and further the stability of the component can be improved. At the same time, it can enable the solder paste in the soldering aid layer to expand to the maximum extent on the electrode, improving the wettability of the solder paste; and it can also reduce the excessive volatilization of the soldering organic matter in the soldering aid layer, ensuring the subsequent welding quality. In addition, adopting the segmented heating method is beneficial to the drying and forming of the soldering aid layer, can improve the density of the cured soldering aid layer, make the surface of the cured soldering aid layer more round and plump, and contribute to improving the subsequent welding effect.

[0026] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0028] Figure 1 is a flowchart of a method for manufacturing a photovoltaic module according to an embodiment of the present application;

[0029] Figure 2 is a flowchart of another method for manufacturing a photovoltaic module according to an embodiment of the present application;

[0030] Figure 3 is a temperature change curve of the soldering aid layer during heating according to an embodiment of the present application;

[0031] Figure 4 is a temperature change curve of the soldering aid layer during heating using a traditional heating method;

[0032] Figure 5 is a schematic structural diagram of the soldering aid layer on the battery cell after drying and curing according to an embodiment of the present application;

[0033] Figure 6 is a schematic welding structure diagram of an interconnecting member and the soldering aid layer according to an embodiment of the present application;

[0034] Figure 7 is a schematic diagram after peeling off the interconnecting member from the welding structure of the interconnecting member and the soldering aid layer according to an embodiment of the present application;

[0035] Figure 8It is a schematic diagram of the distribution structure of sputtering points around the solder mask layer according to an embodiment of the present application.

[0036] Reference numerals:

[0037] 10: solar cell; 20: solder mask layer; 30: interconnecting member; 40: sputtering point. Detailed implementation manners

[0038] Embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary only for explaining the present application and should not be construed as limiting the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts fall within the scope of protection of the present application.

[0039] The terms "first" and "second" in the description and claims of the present application may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise specified, the meaning of "a plurality" is two or more. In addition, "and / or" in the description and claims indicates at least one of the connected objects, and the character " / " generally indicates an "or" relationship between the associated objects before and after.

[0040] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present application.

[0041] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0042] The following will, in conjunction with the accompanying drawings, describe in detail the method for manufacturing a photovoltaic module and the photovoltaic module provided by the embodiments of the present application through specific embodiments and their application scenarios.

[0043] As Figure 1 and Figure 5 shown, Figure 1 FIG. shows a flowchart of a method for manufacturing a photovoltaic module provided by an embodiment of the present application, Figure 5 and FIG. shows a schematic structural diagram of a soldering assistant layer on a solar cell after drying and curing. The method for manufacturing a photovoltaic module in the present application specifically includes the following steps:

[0044] Step 101, form a soldering assistant layer 20 on the surface of the solar cell 10, and connect the soldering assistant layer 20 to the electrodes on the surface of the solar cell 10.

[0045] It can be understood that in the manufacturing process of a photovoltaic module, usually the solar cell 10 is first manufactured, and then the interconnection member 30 (such as a solder ribbon) is electrically connected to the electrodes on the solar cell 10 to connect multiple solar cells 10 to form a battery string, and then a photovoltaic module can be obtained through processes such as lamination and encapsulation. In order to improve the connection effect between the interconnection member 30 and the electrodes, a soldering assistant layer 20 is provided at the connection points of the electrodes, so that when interconnecting, the interconnection member 30 and the soldering assistant layer 20 are locally or completely melted and combined by heating, thereby realizing the fixation and electrical connection of the interconnection member 30 and the electrodes.

[0046] Specifically, a plurality of electrodes are provided on the surface of the solar cell 10, and at least some of the electrodes are provided with connection portions for connecting and fixing with the interconnection member 30. Furthermore, the soldering assistant layer 20 can be formed on the connection portions of the electrodes through processes such as screen printing, spraying, and PVD, so that the soldering assistant layer 20 at least partially covers the connection portions.

[0047] Among them, the soldering assistant layer 20 can be made of a soldering assistant material, such as soldering paste. The main components of the soldering paste include tin, rosin, organic solvents, etc. The soldering assistant layer 20 formed on the electrodes through processes such as screen printing and spraying is in a paste state and needs to be further heated and dried to make the soldering assistant layer 20 tightly combined with the electrodes and the solar cell 10 around the electrodes.

[0048] In some embodiments, the solar cell 10 in the present application can be a main-gridless solar cell 10. A plurality of current collecting electrodes (i.e., fine grid lines) are provided on the surface of the solar cell 10, and at least some of the current collecting electrodes are provided with connection portions, and the soldering assistant layer 20 is provided on the connection portions to connect and fix the interconnection member 30 with the current collecting electrodes.

[0049] In some other embodiments, the cell 10 in the present application may also be a cell with main grids. A plurality of current collecting electrodes and a plurality of bus electrodes (i.e., main grid lines) are provided on the surface of the cell 10. At least some of the bus electrodes are provided with connecting portions, and a soldering assistant layer 20 is provided on the connecting portions so as to connect and fix the interconnecting member 30 to the bus electrodes.

[0050] It should be noted that the connecting portion may be a part of the area on the current collecting electrode or the bus electrode, may also be the area connected to the current collecting electrode or the bus electrode, or may be the thickened section of a certain segment on the current collecting electrode or the bus electrode.

[0051] In some embodiments, the cell 10 may include a front side and a back side which are oppositely arranged, wherein the front side of the cell 10 is the side for receiving light. Further, electrodes and the soldering assistant layer 20 may be provided on both the front side and the back side of the cell 10 simultaneously, or electrodes and the soldering assistant layer 20 may be provided on either the front side or the back side of the cell 10. It can be flexibly set according to the actual structure of the cell 10 and is not limited herein.

[0052] Step 102, heating the soldering assistant layer 20 at a first preset temperature, and the first preset temperature is less than the melting point of the soldering assistant layer 20.

[0053] Specifically, after the soldering assistant layer 20 is formed by processing on the surface of the cell 10, the cell 10 is sent into a heating device to dry and cure the soldering assistant layer 20. In the present application, the soldering assistant layer 20 is first heated at a first preset temperature which is less than the melting point of the soldering assistant layer 20, so that while the solvent in the soldering assistant layer 20 volatilizes, the soldering materials such as tin and rosin in the soldering assistant layer 20 are transformed into a molten state. As the temperature rises, the wettability of the soldering materials gradually increases, so that these soldering materials can slowly expand on the surface of the cell 10, enabling the soldering assistant layer 20 to fully fit with the connecting portion of the electrode.

[0054] Step 103, heating the soldering assistant layer 20 at a second preset temperature to weld and fix the soldering assistant layer 20 to the electrode, and the second preset temperature is greater than or equal to the melting point of the soldering assistant layer 20.

[0055] Specifically, after being heated in step 102, the overall temperature of the soldering assistant layer 20 has risen, and the solvent in the soldering assistant layer 20 has also volatilized sufficiently. Further, the heating temperature is raised above the melting point of the soldering assistant layer 20 to accelerate the melting of the soldering materials in the soldering assistant layer 20. Then, the melted soldering materials can react with the electrode materials, enabling the soldering assistant layer 20 to adhere tightly to the electrode and maintain a certain adhesion force.

[0056] In the embodiments of the present application, by forming a soldering aid layer 20 on the surface of the battery cell 10 and adopting a segmented heating method, compared with quickly heating to the melting point in the prior art, before drying at a temperature higher than the melting point (i.e., heating at the second preset temperature) in the present application, a first preset temperature heating stage with a slow temperature rise is set, which can avoid the serious problem of material splashing of the soldering aid layer 20 caused by directly heating to the melting point temperature quickly. Thus, the probability of solder explosion of the soldering aid layer 20 can be reduced, and the problem of short circuit of the battery cell caused by the sputtering points of the soldering aid layer 20 can be avoided, thereby improving the stability of the component. At the same time, it can make the solder paste in the soldering aid layer 20 expand to the maximum extent on the electrode, improving the wettability of the solder paste; and it can also reduce the excessive volatilization of the soldering organic matter in the soldering aid layer 20, ensuring the subsequent welding quality. In addition, adopting the segmented heating method to dry and form the soldering aid layer 20 can improve the density of the cured soldering aid layer 20, making the surface of the cured soldering aid layer 20 more round and plump, which helps to improve the subsequent welding effect.

[0057] It can be understood that in the preparation process of traditional photovoltaic modules, the soldering aid layer 20 is usually heated and dried at a constant temperature. As Figure 4 shown, Figure 4 shows the temperature change curve of the soldering aid layer when heating the soldering aid layer by the traditional heating method. It can be seen from Figure 4 that in the initial stage of heating, the temperature of the soldering aid layer 20 rises relatively fast. During this process, the external temperature of the soldering aid layer 20 rises rapidly, while the internal temperature has no time to change, resulting in a large temperature difference between the inside and outside of the soldering aid layer 20. And because the temperature of the soldering aid layer 20 changes relatively fast, some soldering materials have no time to change, resulting in local thermal stress concentration inside the soldering aid layer 20, which is likely to cause problems such as local collapse, internal holes, and solder slag splashing in the cured soldering aid layer 20. In addition, keeping the soldering aid layer 20 at a relatively high temperature for a long time will cause the organic components in the soldering aid layer 20 to volatilize excessively, which is not conducive to the subsequent welding of the soldering aid layer 20 and the interconnecting member 30.

[0058] As Figure 3 shown, Figure 3 shows the temperature change curve of the soldering aid layer during the drying process of the soldering aid layer by the segmented heating method of the present application. It can be seen from Figure 3 that during the whole heating and drying process, the temperature of the soldering aid layer 20 first gradually increases and then gradually decreases. In this way, it is not only beneficial to the full reaction of the soldering materials in the soldering aid layer 20, making the cured soldering aid layer 20 denser and the overall structure more round and plump, which can improve the subsequent welding effect of the soldering aid layer 20. At the same time, it also helps the full combination of the soldering materials in the soldering aid layer 20 and the electrode, thereby improving the bonding force between the soldering aid layer 20 and the electrode and avoiding the risk of the soldering aid layer 20 falling off.

[0059] As Figure 2 shown, Figure 2The flowchart of another method for manufacturing a photovoltaic module provided by an embodiment of the present application is shown, which may specifically include the following steps:

[0060] Step 201, form a soldering aid layer 20 on the surface of the cell 10, and connect the soldering aid layer 20 to the electrodes on the surface of the cell 10.

[0061] Specifically, the specific implementation process of this step can be referred to the aforementioned step 101, and the embodiments of the present application will not elaborate herein.

[0062] Step 202, place the cell 10 in the heating chamber of a heating device, and introduce a protective gas into the heating chamber.

[0063] Specifically, the cell 10 with the soldering aid layer 20 formed on its surface in step 201 is sent into the heating chamber of the heating device to heat and dry the soldering aid layer 20 by using the heating device. Before heating, a protective gas is first introduced into the heating chamber of the heating device, so that during the subsequent heating process, the protective gas forms a protection for the cell 10 and its surface components, and avoids reacting with reactive gases such as oxygen at high temperatures.

[0064] Among them, the protective gas can be an inert gas, such as nitrogen, argon, etc. The specific type of the protective gas can be flexibly selected according to the actual situation and is not limited herein.

[0065] Step 203, preheat the soldering aid layer 20 at a third preset temperature, and the third preset temperature is less than or equal to the first preset temperature.

[0066] It can be understood that during the heating process of the soldering aid layer 20, if the soldering aid layer 20 is directly placed in a high-temperature environment for heating, due to the large temperature difference between the inside and outside of the soldering aid layer 20, the phenomenon of sputtering of the soldering aid layer 20 material is likely to occur, and the sputtered soldering aid layer 20 material forms sputtering points 40 on the surface of the cell 10. These sputtering points 40 are likely to form a lap joint with the electrodes on the surface of the cell 10 during the manufacturing process of the photovoltaic module, causing a short-circuit problem.

[0067] In the embodiments of the present application, by first preheating the soldering aid layer 20 at a relatively low temperature, the internal and external structure temperatures of the soldering aid layer 20 can be gradually increased. During this process, the solvent with a relatively low melting point in the soldering aid layer 20 can be volatilized. At the same time, by preheating at a relatively low temperature, the internal and external temperatures of the soldering aid layer 20 can be increased simultaneously, reducing the temperature difference between the inside and outside of the soldering aid layer 20. In this way, the occurrence of sputtering during the subsequent heating process can be reduced.

[0068] In some embodiments, the third preset temperature is T0-50°C to T0-20°C, T0 is the melting point of the soldering layer 20, and the preheating time is 20s to 30s. By controlling the preheating time and preheating temperature, the processing efficiency can be improved while the preheating effect on the soldering layer 20 is achieved.

[0069] Specifically, the third preset temperature can be set according to the melting point T0 of the soldering layer 20. For example, the third preset temperature can be set to: T0-50°C, T0-45°C, T0-40°C, T0-35°C, T0-30°C, T0-25°C, T0-20°C, etc.

[0070] Specifically, the preheating time can be set to any value such as 20s, 22s, 24s, 25s, 27s, 28s, 30s, or a range between any two values.

[0071] Step 204 , heating the soldering layer 20 at a first preset temperature, where the first preset temperature is lower than the melting point of the soldering layer 20 .

[0072] Specifically, the specific implementation process of this step can refer to the aforementioned step 102, and the embodiment of the present application will not be repeated here.

[0073] In some embodiments, step 204 may include: heating the soldering layer 20 for a first preset time at the first preset temperature, wherein the first preset time is 40s to 50s, and the first preset temperature is: T0-50°C to T0-20°C, and T0 is the melting point of the soldering layer 20.

[0074] Specifically, the first preset temperature can be set to: T0-50°C, T0-45°C, T0-40°C, T0-35°C, T0-30°C, T0-25°C, T0-20°C, etc.

[0075] Specifically, the first preset time can be set to any value such as 40s, 42s, 44s, 45s, 47s, 48s, 50s, etc., or a range between any two values.

[0076] In the embodiment of the present application, after preheating in step 203, the overall temperature of the soldering layer 20 has increased, and its wettability has also increased accordingly. By maintaining the first preset temperature for a certain period of time, the soldering material in the soldering layer 20 is diffused on the electrode, ensuring that the soldering layer 20 is in full contact with the connecting portion of the electrode.

[0077] Step 205 , heating the soldering layer 20 at a second preset temperature so that the soldering layer 20 is welded and fixed to the electrode, and the second preset temperature is greater than or equal to the melting point of the soldering layer 20 .

[0078] Specifically, the specific implementation process of this step can be carried out by referring to the aforementioned step 103, and the embodiments of the present application will not be elaborated herein.

[0079] In some embodiments, step 205 includes: heating the solder layer 20 at the second preset temperature for a second preset time, where the second preset time is 22 s to 26 s, and the second preset temperature is: T0 to T0 + 50 °C, and T0 is the melting point of the solder layer 20.

[0080] Specifically, the second preset temperature can be set to: T0, T0 + 10 °C, T0 + 20 °C, T0 + 30 °C, T0 + 40 °C, T0 + 50 °C, etc.

[0081] Specifically, the second preset time can be set to any value such as 22 s, 23 s, 24 s, 25 s, 26 s, etc. or the range between any two values.

[0082] In the embodiments of the present application, after the solder layer 20 is expanded and in full contact with the electrode through step 204, the heating temperature is rapidly increased to above the melting point of the solder layer 20, so that the soldering material in the solder layer 20 reacts with the electrode material, thereby ensuring that the solder layer 20 adheres better to the electrode.

[0083] It can be understood that the second preset time is less than the first preset time. In this way, it is ensured that the soldering material in the solder layer 20 expands to the maximum extent at the first set temperature, improving the wettability of the soldering material, so that the solder layer 20 is in full contact with the electrode. At the same time, it is avoided that the time of the solder layer 20 at the second preset temperature is too long, resulting in excessive volatilization of the organic matter in the solder layer 20, and ensuring the subsequent welding quality of the solder layer 20.

[0084] Step 206, cooling the solder layer 20 to a fourth preset temperature, and the cooling time is greater than or equal to 35 s, and the fourth preset temperature is 30 °C to 50 °C.

[0085] Specifically, the fourth preset temperature is any value such as 30 °C, 31 °C, 33 °C, 35 °C, 38 °C, 40 °C, 45 °C, 48 °C, 50 °C, etc. or the range between any two values.

[0086] Specifically, the cooling time can be set to: 35 s, 38 s, 40 s, 45 s, 50 s, 55 s, 60 s, etc.

[0087] It is understandable that after heating the solder mask layer 20 is completed, the temperature of the solder mask layer 20 is controlled to gradually decrease to complete the entire drying process. In this application, by slowly cooling the heated solder mask layer 20, the concentration of thermal stress inside the solder mask layer 20 is reduced, and problems such as surface collapse of the solder mask layer 20 after cooling and a large number of holes inside are avoided. At the same time, the solder mask layer 20 and the electrodes can also maintain relatively low shrinkage rates, so that the solder mask layer 20 is closely attached to the electrodes, ensuring the bonding force between the solder mask layer 20 and the electrodes and reducing the risk of the solder mask layer 20 falling off.

[0088] In some embodiments, as Figures 5 to 7 shown, the solder mask layer 20 after drying and cooling is hemispherical or quasi-hemispherical. Furthermore, the interconnect 30 can be pressure-welded onto the solder mask layer 20, which can ensure the welding strength between the interconnect 30 and the solder mask layer 20.

[0089] In some embodiments, the heating chamber of the heating device has a certain length. For example, the length of the heating chamber is 5 m, and the drying operation is completed by passing the battery cell 10 through the heating chamber during the heating process. Furthermore, along the moving direction of the battery cell 10, the heating chamber is sequentially divided into a preheating area, a wetting area, a reflow soldering area, and a cooling area. Correspondingly, the temperature of the preheating area is set to a third preset temperature, the temperature of the wetting area is set to a first preset temperature, the temperature of the reflow soldering area is set to a second preset temperature, and the temperature of the cooling area is set to a fourth preset temperature. And by setting the length of each area, the residence time of the battery cell in each area can be controlled.

[0090] As Figure 3 shown, Figure 3 shows the temperature change curve of the solder mask layer during the heating process in the embodiment of the present application. It should be noted that Figure 3 the temperature curve in Figure 3 is the actual temperature change of the solder mask layer during the heating process. Among them,

[0091] During the heating operation, the battery cell 10 is passed through the preheating area, the wetting area, the reflow soldering area, and the cooling area in sequence, and the residence time of the battery cell 10 in each area is controlled to perform segmented heating on the solder mask layer 20 on the battery cell 10. As Figure 3 shown, during the drying process, the temperature of the solder mask layer 20 gradually changes, so that the solder mask layer 20 is fully combined with the electrodes. At the same time, it also helps the formation of the overall structure of the solder mask layer 20, making the cured solder mask layer hemispherical or quasi-hemispherical, thus helping to improve the welding effect between the subsequent solder mask layer and the interconnect.

[0092] It should be noted that in specific applications, the solar cell 10 can also be placed stationary in a heating device, and by setting the heating program of the heating device, the soldering assistant layer 20 on the solar cell 10 can be heated in segments. The specific settings can be flexibly selected according to the structure of the heating device and are not limited herein.

[0093] In the embodiment of the present application, by adopting the method of segmental heating to dry and cure the soldering assistant layer 20 on the solar cell 10, not only can the sputtering problem during the heating process be reduced, but also the soldering assistant material in the soldering assistant layer 20 can fully expand on the electrode to improve the bonding force between the solder layer and the electrode. Moreover, by controlling the soldering assistant layer 20 to gradually heat up and cure, the density of the cured soldering assistant layer 20 can be improved, and the surface of the cured soldering assistant layer 20 is more round and plump, which helps to improve the subsequent welding effect.

[0094] Optionally, the embodiment of the present application also provides a photovoltaic module, which includes: a plurality of solar cells 10 and interconnectors 30; a plurality of electrodes are provided on the surface of the solar cell 10, the electrodes have connecting parts, at least part of the connecting parts are covered with the soldering assistant layer 20, and the interconnectors 30 are at least partially embedded in the soldering assistant layer 20; sputtering points 40 are distributed around the soldering assistant layer 20, and the distance between the sputtering points 40 and the soldering assistant layer 20 is less than or equal to 1.5 mm.

[0095] In the embodiment of the present application, by providing the soldering assistant layer 20 on the connecting parts of the electrodes in the solar cell 10, the soldering assistant layer 20 can be used to assist the connection and fixation of the interconnector 30 and the electrode, thereby enhancing the connection effect between the interconnector 30 and the electrode. At the same time, by controlling the distance between the sputtering points 40 distributed around the soldering assistant layer 20 and the soldering assistant layer 20, the problem of short circuit caused by the sputtering points 40 overlapping with the electrodes on the surface of the solar cell 10 can be avoided, thereby improving the quality of the photovoltaic module.

[0096] It should be noted that the photovoltaic module in the embodiment of the present application can adopt the above preparation method to form the dried and cured soldering assistant layer 20 on the surface of the solar cell 10, and then the interconnector 30 and the soldering assistant layer 20 are welded by welding to realize the connection and fixation of the interconnector 30 and the electrode.

[0097] As Figure 8 shown, during the heating process of the soldering assistant layer, as the temperature of the soldering assistant layer 20 increases, a certain sputtering phenomenon will occur, and sputtering points will be formed by sputtering around the soldering assistant layer. In the present application, by adopting the method of segmental heating, the temperature change of the soldering assistant layer is controlled to avoid serious sputtering problems caused by the too-fast temperature rise of the soldering assistant layer 20, so as to control the distribution of the sputtering points 40 around the soldering assistant layer within a certain range.

[0098] It should be noted that when the cell 10 is a main-gridless cell 10, the electrode in the present application refers to the current collecting electrode on the surface of the cell 10, that is, the fine grid line; and when the cell 10 is a main-grid cell 10, the electrode in the present application refers to the busbar electrode on the surface of the cell 10, that is, the main grid line.

[0099] Optionally, along the direction perpendicular to the surface of the cell 10, the orthographic projection area of the sputtering point 40 is less than or equal to 0.03 mm 2 . For example, the orthographic projection area of the sputtering point 40 can be set to: 0.01 mm 2 , 0.013 mm 2 , 0.015 mm 2 , 0.018 mm 2 , 0.02 mm 2 , 0.022 mm 2 , 0.025 mm 2 , 0.028 mm 2 , 0.03 mm 2 and so on.

[0100] In the embodiment of the present application, by setting the orthographic projection area of the sputtering point 40 to be less than or equal to 0.03 mm 2 , the size of the sputtering point 40 can be controlled, thereby reducing the risk of the sputtering point 40 overlapping with other electrodes and avoiding the short-circuit problem caused by the overlap, thereby improving the quality of the photovoltaic module.

[0101] Optionally, the welding strength between the interconnector 30 and the solder layer 20 is: 1.5 MPa to 4 MPa. For example, the welding strength can be set to: 1.5 MPa, 1.7 MPa, 2 MPa, 2.5 MPa, 2.7 MPa, 3 MPa, 3.5 MPa, 3.8 MPa, 4 MPa, etc.

[0102] In the embodiment of the present application, adopting the photovoltaic module structure in the present application can effectively improve the welding strength between the interconnector 30 and the solder layer 20, thereby improving the connection reliability between the interconnector 30 and the electrode and improving the quality of the photovoltaic module.

[0103] Specifically, the detection method for the welding strength between the interconnector 30 and the solder layer 20 includes: fixing the cell 10 in the base of the tensile test equipment, using the fixture in the tensile test equipment to clamp and fix the solder tape, starting the equipment, and using the fixture to pull the solder tape to move relative to the cell 10, so as to test the welding strength value when the solder tape is separated from the cell 10.

[0104] In some embodiments, the traditional constant-temperature heating method and the staged heating method in the present application are respectively used to heat and dry the solder assistant layer 20 on the battery chip 10, and the interconnecting member 30 is welded to the cured soldering layer to prepare a battery sample. Then, the welding performance of the prepared test sample is tested.

[0105] Among them, the comparative example is the battery sample prepared by the constant-temperature heating method, and the example is the battery sample prepared by the staged heating method in the present application. Except for the different heating methods in the comparative example and the example, the number, structure, and processing technology of the prepared battery samples are the same.

[0106] By testing the battery samples of the comparative example and the example, and judging and counting the qualified rate of the battery samples according to the same standard. Through experimental verification, compared with the comparative example, the average welding strength of the battery sample of the example can be increased by 16% compared with the average welding strength of the battery sample of the comparative example. Moreover, compared with the comparative example, the qualified rate of the battery sample of the example has increased by 17%.

[0107] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0108] Although the embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present application. The scope of the present application is defined by the claims and their equivalents.

Claims

1. A method for preparing a photovoltaic module, characterized in that, Including: Forming a soldering aid layer on the surface of the battery cell, and connecting the soldering aid layer to the electrodes on the surface of the battery cell; wherein, one of the front or back surfaces of the battery cell is provided with the electrodes and the soldering aid layer, at least part of the electrodes are provided with connecting parts, and at least part of the soldering aid layer covers the connecting parts; Heating the soldering aid layer at a first preset temperature, the first preset temperature being less than the melting point of the soldering aid layer; Heating the soldering aid layer at a second preset temperature to weld and fix the soldering aid layer to the electrodes, the second preset temperature being greater than or equal to the melting point of the soldering aid layer.

2. The manufacturing method of the photovoltaic module according to claim 1, characterized in that, Before heating the soldering aid layer at the first preset temperature, further including: Preheating the soldering aid layer at a third preset temperature, the third preset temperature being less than or equal to the first preset temperature.

3. The manufacturing method of the photovoltaic module according to claim 2, characterized in that, The third preset temperature is from T0 - 50°C to T0 - 20°C, where T0 is the melting point of the soldering aid layer, and the preheating time is 20s to 30s.

4. The manufacturing method of the photovoltaic module according to claim 1, characterized in that, After heating the soldering aid layer at the second preset temperature, further including: Cooling the soldering aid layer to a fourth preset temperature, the cooling time being greater than or equal to 35s, and the fourth preset temperature being in the range of 30°C to 50°C.

5. The preparation method of the photovoltaic module according to claim 4, wherein, The soldering aid layer after cooling is hemispherical or quasi-hemispherical.

6. The manufacturing method of the photovoltaic module according to claim 1, wherein, After forming the soldering aid layer on the surface of the battery cell and before heating the soldering aid layer at the first preset temperature, further including: Placing the battery cell in the heating chamber of a heating device and introducing a protective gas into the heating chamber.

7. The manufacturing method of the photovoltaic module according to any one of claims 1-6, characterized in that, The heating of the soldering aid layer at the first preset temperature includes: Heating the soldering aid layer at the first preset temperature for a first preset time, where the first preset time is 40s to 50s, and the first preset temperature is in the range of T0 - 50°C to T0 - 20°C, and T0 is the melting point of the soldering aid layer.

8. The manufacturing method of the photovoltaic module according to any one of claims 1-6, characterized in that, The heating of the soldering aid layer at the second preset temperature includes: Heating the soldering aid layer at the second preset temperature for a second preset time, where the second preset time is 22s to 26s, and the second preset temperature is in the range of T0 to T0 + 50°C, and T0 is the melting point of the soldering aid layer.

9. A photovoltaic module, characterized in that, Including: A plurality of battery cells and interconnecting members; One of the front or back surfaces of the battery cell is provided with electrodes and a soldering aid layer, at least part of the electrodes have connecting parts, at least part of the soldering aid layer covers the connecting parts, and at least part of the interconnecting members are embedded in the soldering aid layer; Sputtering points are distributed around the soldering aid layer, and the distance between the sputtering points and the soldering aid layer is less than or equal to 1.5mm.

10. The photovoltaic module according to claim 9, wherein In the direction perpendicular to the surface of the cell, the orthographic projection area of the sputtering point is less than or equal to 0.03 mm 2 .

11. The photovoltaic module according to claim 9 or 10, characterized in that, The welding strength between the interconnecting member and the soldering aid layer is 1.5MPa to 4MPa.

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