HJT solar cell, cell string, cell assembly and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides an HJT solar cell piece, a cell string, a cell module and a photovoltaic system, in the HJT solar cell piece, a plurality of first welding seed layers are directly arranged on a first transparent conductive film to be directly welded with a welding strip, and when the cell string and the cell module are formed, the first welding seed layers are directly welded with the welding strip; the series connection between the battery pieces can be realized only by directly covering the first welding strip on the first welding seed layer in parallel and welding the first welding strip with the first welding seed layer, and a mode of printing silver paste to form an electrode on the first transparent conductive film and then welding the welding strip to collect current is not needed, so that the cost is greatly reduced. And meanwhile, the battery can be manufactured on the first transparent conductive film without adopting an electro-coppering process, so that the yield of products can be improved. In addition, the first anti-oxidation protection layer is arranged on the first welding seed layer, so that the situation that the first welding seed layer is exposed in the air for a long time to generate oxide, and consequently the welding performance becomes poor can be effectively avoided.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to an HJT solar cell, cell string, cell module and photovoltaic system. Background Technology

[0002] Currently, in the photovoltaic industry, HJT (heterojunction) solar cells typically form electrodes by printing low-temperature silver paste or electroplating copper onto a TCO film. The silver grid lines or the copper electrodes formed by electroplating serve as conductors to collect current. However, the materials for printing low-temperature silver paste are very expensive, significantly increasing costs; and the copper electroplating process is not mature enough, is difficult, and results in a relatively low product yield. Utility Model Content

[0003] This application provides an HJT solar cell, a cell string, a cell module, and a photovoltaic system.

[0004] This application is implemented as follows: the HJT solar cell in the embodiments of this application includes:

[0005] A silicon wafer having opposing first and second surfaces;

[0006] A first intrinsic amorphous silicon layer, a first doped amorphous silicon layer, and a first transparent conductive film are sequentially stacked on the first surface;

[0007] A second intrinsic amorphous silicon layer, a second doped amorphous silicon layer, and a second transparent conductive film are sequentially stacked on the second surface;

[0008] A plurality of first welding seed layers are disposed on the first transparent conductive film, the plurality of first welding seed layers are arranged at intervals along a first direction, and the first welding seed layers all extend along a second direction, the second direction intersecting the first direction; the first welding seed layers are used to weld to the welding strip located above and covering the first welding seed layer.

[0009] A first antioxidant protective layer disposed on the first welding seed layer; and

[0010] A current collection structure disposed on the second transparent conductive film.

[0011] Furthermore, the first solder seed layer includes a seed copper layer; and / or

[0012] The first antioxidant protective layer includes at least one of a tin layer, a nickel layer, and a metal oxide layer.

[0013] Furthermore, the first antioxidant protective layer includes at least one of a tin layer, a nickel layer, and a metal oxide layer.

[0014] Furthermore, the first antioxidant protective layer is a magnetic layer or contains magnetic materials, so that the first antioxidant protective layer can generate a magnetic attraction force on the solder ribbon.

[0015] Furthermore, the thickness of the first welding seed layer is 60nm-150nm; and / or

[0016] The thickness of the first antioxidant protective layer is 50nm-20um.

[0017] Furthermore, the first welding seed layer contains a magnetic material so that it can generate a magnetic attraction force on the welding strip.

[0018] Furthermore, the current collection structure includes a plurality of second welding seed layers, which are also arranged at intervals along the first direction, and all the second welding seed layers extend along the second direction;

[0019] The second welding seed layer is used for welding to the welding strip located above and covering the second welding seed layer.

[0020] Furthermore, the thickness of the second welding seed layer is 60nm-150nm.

[0021] Furthermore, a second antioxidant protective layer is provided on the second welding seed layer.

[0022] Furthermore, the second antioxidant protective layer includes at least one of a tin layer, a nickel layer, and a metal oxide layer.

[0023] Furthermore, the second antioxidant protective layer is a magnetic layer or contains magnetic materials, so that the second antioxidant protective layer can generate a magnetic attraction force on the solder ribbon.

[0024] Furthermore, the thickness of the second antioxidant protective layer is 50nm-20um.

[0025] Furthermore, the second welding seed layer contains a magnetic material so that it can generate a magnetic attraction force on the welding strip.

[0026] This application also provides a battery string, comprising:

[0027] A plurality of HJT solar cells as described in any one of the preceding claims are arranged at intervals along the second direction, and all the HJT solar cells are oriented in the same direction; and

[0028] A first solder strip is disposed on the first welding seed layer, the first solder strip covers the first welding seed layer and is welded to the first welding seed layer;

[0029] Wherein, the first solder strip on the Nth HJT solar cell is electrically connected to the current collection structure of the (N+1)th HJT solar cell, where N is a positive integer.

[0030] Furthermore, the current harvesting structure includes a plurality of second welding seed layers formed on the second transparent conductive film and spaced apart along the first direction;

[0031] In this case, the first solder strip on the Nth HJT solar cell bends and extends towards the side where the second solder seed layer of the N+1th HJT solar cell is located at the interval between two adjacent HJT solar cells and is soldered to the second solder seed layer.

[0032] Furthermore, the first solder strip includes a first straight portion, a bent portion, and a second straight portion. The first straight portion is parallel to and covers the first solder seed layer of the Nth HJT solar cell and is soldered to the first solder seed layer. The bent portion is located in the interval area between two adjacent HJT solar cells. The second straight portion is parallel to and covers the second solder seed layer of the N+1th HJT solar cell and is soldered to the second solder seed layer.

[0033] Furthermore, the battery string includes at least one end battery piece located at the end of the battery string, wherein the first solder strip is not covered on the second solder seed layer on the end battery piece; the battery string also includes a second solder strip disposed on the second solder seed layer of the end battery piece and soldered to the second solder seed layer.

[0034] Furthermore, the current harvesting structure includes a plurality of second welding seed layers formed on the second transparent conductive film and spaced apart along the first direction;

[0035] The battery string also includes a third solder strip disposed on and welded to the second solder seed layer, and a conductive connector disposed in the interval area between two adjacent HJT solar cells. The conductive connector is connected to the first solder strip on the Nth HJT solar cell and the third solder strip on the N+1th HJT solar cell.

[0036] This application also provides a battery assembly including the battery string described in any of the above claims.

[0037] This application also provides a photovoltaic system including the aforementioned battery module.

[0038] In the HJT solar cell, cell string, cell module, and photovoltaic system of this application embodiment, on the one hand, several first welding seed layers are directly disposed on the first transparent conductive film for direct welding with the welding ribbon. When forming the cell string and cell module, it is only necessary to directly cover the first welding seed layer in parallel with the first welding seed layer and weld it to achieve series connection between the cells. There is no need to form electrodes by printing silver paste on the first transparent conductive film and then welding the welding ribbon to collect current, which greatly reduces costs. At the same time, there is no need to use the electroplating copper process on the first transparent conductive film to make the cell, which can improve the product yield. In addition, by setting a first anti-oxidation protective layer on the first welding seed layer, the first anti-oxidation protective layer can protect the first welding seed layer, effectively preventing the first welding seed layer from being exposed to the air for a long time and generating oxides, which would lead to a deterioration in welding performance. At the same time, it can also prevent the phenomenon of organic matter, dust, and other impurities adhering to the surface of both, which would lead to poor appearance.

[0039] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a photovoltaic system module provided in an embodiment of this application;

[0041] Figure 2 This is a schematic diagram of a battery assembly provided in an embodiment of this application;

[0042] Figure 3 This is a schematic diagram of the planar structure of the HJT solar cell provided in the embodiments of this application;

[0043] Figure 4 yes Figure 3 A schematic diagram of the cross-sectional structure of the HJT solar cell along line IV-IV;

[0044] Figure 5 This is a schematic diagram of the battery string structure provided in the embodiments of this application;

[0045] Figure 6 This is another cross-sectional structural diagram of the HJT solar cell provided in the embodiments of this application;

[0046] Figure 7 This is another cross-sectional structural schematic diagram of the HJT solar cell provided in the embodiments of this application;

[0047] Figure 8 This is another schematic diagram of the battery string structure provided in the embodiments of this application;

[0048] Figure 9 This is another schematic diagram of the battery string provided in the embodiments of this application.

[0049] Explanation of key component symbols:

[0050] Photovoltaic system 1000, battery module 300, battery string 200, HJT solar cell 100, silicon wafer 10, first surface 11, second surface 12, first intrinsic amorphous silicon layer 13, first doped amorphous silicon layer 14, first transparent conductive film 15, second intrinsic amorphous silicon layer 16, second doped amorphous silicon layer 17, second transparent conductive film 18, first welding seed layer 20, first anti-oxidation protective layer 30, current bus structure 40, second welding seed layer 41, second anti-oxidation protective layer 50;

[0051] First welding strip 210, first straight portion 211, bent portion 212, second straight portion 213, second welding strip 220, third welding strip 230, conductive connector 240. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. It should be noted that the embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0053] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "lateral", "longitudinal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0054] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "several" means two or more, unless otherwise explicitly specified.

[0055] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0056] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0057] Please see Figure 1 and Figure 2 The photovoltaic system 1000 in this application embodiment may include the battery module 300 in this application embodiment, and the battery module 300 in this application embodiment may include a plurality of battery strings 200 in this application embodiment.

[0058] The battery string 200 in this application embodiment may include a plurality of HJT solar cells 100 in this application embodiment.

[0059] Please see Figure 3 and Figure 4 The HJT solar cell 100 in this embodiment may include a silicon wafer 10, a first intrinsic amorphous silicon layer 13, a first doped amorphous silicon layer 14, a first transparent conductive film 15, a second intrinsic amorphous silicon layer 16, a second doped amorphous silicon layer 17, a second transparent conductive film 18, a plurality of first welding seed layers 20, a first anti-oxidation protective layer 30, and a current collection structure 40.

[0060] like Figure 4 As shown, the silicon wafer 10 has a first surface 11 and a second surface 12 opposite to each other. The first surface 11 and the second surface 12 are the front and back sides of the silicon wafer 10, respectively. When the first surface 11 is the front side, the second surface 12 is the back side, and when the first surface 11 is the back side, the second surface 12 is the front side.

[0061] A first intrinsic amorphous silicon layer 13, a first doped amorphous silicon layer 14, and a first transparent conductive film 15 are sequentially stacked on the first surface 11. A second intrinsic amorphous silicon layer 16, a second doped amorphous silicon layer 17, and a second transparent conductive film 18 are sequentially stacked on the second surface 12.

[0062] A plurality of first welding seed layers 20 are disposed on a first transparent conductive film 15. The plurality of first welding seed layers 20 are arranged at intervals along a first direction, and each of the first welding seed layers 20 extends along a second direction, which intersects the first direction. The first welding seed layers 20 are used to weld to solder strips (such as the first solder strip 210 described below) located above and covering the first welding seed layers 20. In the embodiments of this application, each first welding seed layer 20 is correspondingly provided with a solder strip, and the two are in one-to-one correspondence.

[0063] The first antioxidant protective layer 30 is disposed on the first welding seed layer 20, and the current collection structure 40 is disposed on the second transparent conductive film 18.

[0064] like Figure 5 As shown, in the battery string 200, the battery string 200 may include a plurality of HJT solar cells 100 and a plurality of first solder strips 210. All HJT solar cells 100 are arranged in the same direction. That is to say, in the battery string 200, the first solder seed layer 20 in all HJT solar cells 100 are located on the same side, and the current collection structure 40 is also located on the same side.

[0065] Several HJT solar cells 100 are arranged at intervals along a second direction. A first solder strip 210 is disposed on a first solder seed layer 20, the first solder strip 210 covers the first solder seed layer 20 and is soldered to the first solder seed layer 20, and each first solder seed layer 20 corresponds to one first solder strip 210.

[0066] In this configuration, the first solder strip 210 on the Nth HJT solar cell 100 is electrically connected to the current collection structure 40 of the (N+1)th HJT solar cell 100, where N is a positive integer. That is, the first solder strip 210 is electrically connected to both the first solder seed layer 20 on the Nth HJT solar cell 100 and the current collection structure 40 on the (N+1)th HJT solar cell 100. The first solder strips 210 on adjacent HJT solar cells are not directly connected, thus achieving sequential series connection of the cells.

[0067] In the embodiments of this application, the second direction may be the stringing direction of each HJT solar cell 100 in the battery string 200, and the first direction intersects with the second direction; for example, the first direction may be perpendicular to the second direction, the second direction is the stringing direction of the HJT solar cell 100 when forming the battery string 200, and the first direction is the direction perpendicular to the stringing direction.

[0068] In the HJT solar cell 100, cell string 200, cell module 300, and photovoltaic system 1000 of this application embodiment, on the one hand, several first welding seed layers 20 are directly disposed on the first transparent conductive film 15 for direct welding with the welding ribbon. When forming the cell string 200 and cell module 300, it is only necessary to directly cover the first welding seed layer 20 with the first welding seed layer 20 in parallel and weld it to achieve series connection between the cells. There is no need to form electrodes by printing silver paste on the first transparent conductive film 15 and then welding the welding ribbon to collect current, which greatly reduces the cost. At the same time, there is no need to use the electroplating copper process on the first transparent conductive film 15 to make the cells, which can improve the product yield. In addition, by providing a first anti-oxidation protective layer 30 on the first welding seed layer 20, the first anti-oxidation protective layer 30 can protect the first welding seed layer 20, which can effectively prevent the first welding seed layer 20 from being exposed to the air for a long time and generating oxides, which would lead to a deterioration in welding performance. At the same time, it can also prevent the appearance of organic matter, dust and other impurities from adhering to the surface of both.

[0069] Specifically, in the embodiments of this application, the silicon wafer 10 may be an N-type silicon wafer or a P-type silicon wafer, and one of the first doped amorphous silicon layer 14 and the second doped amorphous silicon layer 17 is a P-type doped amorphous silicon layer and the other is an N-type doped amorphous silicon layer.

[0070] In the battery string 200, the number of first solder strips 210 can be equal to the number of first solder seed layers 20. Each first solder seed layer 20 is soldered together with a first solder strip 210, and the first solder strip 210 completely covers the first solder seed layer 20.

[0071] The first welding seed layer 20 and the first solder strip 210 are used to collect the current collected by the first transparent conductive film 15, and the current bus structure 40 is used to collect the current collected by the second transparent conductive film 18. For example, in one embodiment, the first welding seed layer 20 and the first solder strip 210 are used to collect the positive current, and the current bus structure 40 is used to collect the negative current. Conversely, if the first welding seed layer 20 is used to collect the negative current, the current bus structure 40 is used to collect the positive current.

[0072] like Figure 5As shown, in the battery string 200, in the series connection direction (i.e., the second direction) of the battery string 200, the first solder strip 210 on the previous HJT solar cell 100 is connected to the current bus structure 40 on the next HJT solar cell 100, while the first solder strips 210 on the two adjacent HJT solar cells 100 are insulated from each other, thereby realizing the current bus output of the entire battery string 200.

[0073] In some embodiments, the first solder seed layer 20 may include a seed copper layer. The seed copper layer has good solderability and sufficiently low bulk resistance, which reduces resistance loss, while also being relatively inexpensive. Of course, in other embodiments, the first solder seed layer 20 may also be other metal seed layers with low solderability and resistance, such as a silver layer, a silver-aluminum alloy layer, etc.

[0074] For example, the first welding seed layer 20 can be obtained by first depositing a full-surface seed layer on the first transparent conductive film 15, then printing a patterned mask on the seed layer, and then etching the areas not covered by the mask.

[0075] Of course, in some embodiments, a seed layer can be deposited on the first transparent conductive film 15 first, and then several first solder ribbons 210 can be directly laid on the seed layer and soldered to the seed layer. Subsequently, the first solder ribbons 210 are used as a shielding layer to etch the seed layer that is not shielded by the first solder ribbons 210, thereby directly obtaining the HJT solar cell 100 with the first solder ribbons 210.

[0076] In some embodiments, the thickness of the first welding seed layer 20 may be 60nm-150nm.

[0077] Thus, by setting the thickness of the first welding seed layer 20 within this reasonable range, it is possible to effectively avoid the first welding seed layer 20 being too thin and unable to form a stable weld with the first welding strip 210, thus ensuring stability and reliability. At the same time, it is also possible to avoid the first welding seed layer 20 being too thick, which would lead to increased costs.

[0078] Specifically, in such an embodiment, the thickness of the first welding seed layer 20 can be, for example, any value between 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm, 105nm, 110nm, 115nm, 120nm, 125nm, 130nm, 135nm, 140nm, 145nm, 150nm, or 60nm-150nm, without any specific limitation herein.

[0079] In such an embodiment, the thickness of the first welding seed layer 20 is preferably 80nm-120nm. Specifically, through research and verification by the inventors of this application, it has been found that when the thickness of the first welding seed layer 20 is less than 80nm, although it can form a weld with the first solder strip 210, it is easily susceptible to unstable welding under the influence of external forces. Conversely, if the thickness of the first welding seed layer 20 is greater than 120nm, the cost will increase significantly. After research, the inventors of this application have set the thickness of the first welding seed layer 20 within the preferred range of 80nm-120nm, which can reduce costs while maximizing welding stability and reliability.

[0080] Understandably, in this application, the first welding seed layer 20 serves the function of welding and collecting charge carriers, and it needs to be fabricated using a relatively active metal seed layer, such as the seed copper layer mentioned above. However, highly active metal seed layers are prone to oxidation, which leads to a deterioration in subsequent welding performance. Therefore, this application effectively avoids this situation by providing a first anti-oxidation protective layer 30 on the first welding seed layer 20.

[0081] Specifically, the first antioxidant protective layer 30 can be an inert metal layer. For example, in some embodiments, the first antioxidant protective layer 30 can be at least one of a tin layer, a nickel layer, and a metal oxide layer, which can be formed on the first solder seed layer 20 by PVD deposition, inkjet printing, or other methods. Alternatively, it can be formed by heat treatment.

[0082] Of course, in other embodiments, the first antioxidant protective layer 30 may also be an organic or inorganic film layer capable of resisting oxidation, such as an inorganic film layer with a chain structure. The specific type is not limited here, but an inert metal layer is preferred.

[0083] Furthermore, in some embodiments, the first antioxidant protective layer 30 may also be a magnetic layer, so that the first antioxidant protective layer 30 can generate a magnetic attraction force on the first solder ribbon 210. In this way, during the welding process with the first solder ribbon 210, the first antioxidant protective layer 30 can adsorb the first solder ribbon 210, which can effectively prevent the first solder ribbon 210 from shifting during the welding process, improve the stability and reliability of the welding. That is to say, the first antioxidant protective layer 30 can not only effectively prevent the oxidation of the first welding seed layer 20, but also position and pre-fix the first solder ribbon 210 during the welding process.

[0084] Specifically, in such embodiments, the magnetic layer refers to a film layer that has magnetic adsorption function itself or a film layer that has magnetic adsorption function after being energized. The magnetic layer can be made entirely of magnetic materials.

[0085] Of course, it is understood that in some embodiments, the first antioxidant protective layer 30 may not be a magnetic layer made entirely of magnetic materials, but may contain magnetic material components. For example, magnetic materials may be added to inert metal layers such as tin layer, nickel layer and metal oxide layer as described above, so that the first antioxidant protective layer 30 can generate magnetic attraction to the first solder ribbon 210.

[0086] In addition, some metal particles may be spattered during the welding process. The magnetic attraction can be used to attract some of these metal particles, thereby reducing surface contamination of the solar cells, improving the light absorption capacity of the solar cells, and increasing the light conversion efficiency of the solar cells.

[0087] It is easy to understand that the first antioxidant protective layer 30 will melt and flow during the welding process. Therefore, in the final battery string 200 and battery assembly 300, there may be a phenomenon where the first antioxidant protective layer 30 is absent between some or all areas of the first welding seed layer 20 and the first welding strip 210.

[0088] In some embodiments, the thickness of the first antioxidant protective layer 30 can be 50 nm to 20 μm. Setting the thickness of the first antioxidant protective layer 30 within this reasonable range avoids both insufficient anti-oxidation effect due to excessive thickness and increased cost due to excessive thickness.

[0089] Specifically, the thickness of the first antioxidant protective layer 30 can be, for example, any value between 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 70nm, 800nm, 900nm, 1um, 1um, 2um, 3um, 4um, 5um, 6um, 7um, 8um, 9um, 10um, 11um, 12um, 13um, 14um, 15um, 16um, 17um, 18um, 19um, 20um, or 50nm-20um, without any specific limitation.

[0090] In some embodiments, the first welding seed layer 20 may contain a magnetic material to enable it to generate a magnetic attraction force on the solder strip. Thus, during the welding process with the first solder strip 210, the first welding seed layer 20 can also attract the first solder strip 210, effectively preventing the first solder strip 210 from shifting during welding and improving the stability and reliability of the welding process.

[0091] Please see Figure 6In some embodiments, the current collection structure 40 includes a plurality of second welding seed layers 41, which are also arranged at intervals along a first direction and extend along a second direction. The second welding seed layers 41 are used to weld to solder strips (such as the first solder strip 210, the second solder strip 220, and the third solder strip 230 mentioned below) located above the second welding seed layers 41 and covering the first welding seed layer 20, with each second welding seed layer 41 corresponding to one solder strip.

[0092] Therefore, there is no need to form electrodes by printing silver paste on the second transparent conductive film 18 and then soldering solder strips to collect current, which greatly reduces costs. At the same time, there is no need to use the electroplating copper process on the second transparent conductive film 18 to manufacture the battery, which can improve the product yield.

[0093] In some embodiments, the second welding seed layer 41 may also include a seed copper layer. Seed copper layers offer good welding performance and have sufficiently low bulk resistance, reducing resistance loss, while also being relatively inexpensive. Of course, in other embodiments, the second welding seed layer 41 may also be other metal seed layers with low welding performance and resistance, such as a silver layer, a silver-aluminum alloy layer, etc.

[0094] For example, the second welding seed layer 41 can be obtained by first depositing a seed layer on the second transparent conductive film 18, then printing a patterned mask on the seed layer, and then etching the area not covered by the mask.

[0095] Of course, in some embodiments, a seed layer can be deposited on the second transparent conductive film first, and then several solder ribbons can be laid directly on the seed layer and soldered to the seed layer. Subsequently, the solder ribbons are used as a shielding layer to etch the seed layer that is not shielded by the solder ribbons, thereby obtaining the HJT solar cell 100 with solder ribbons.

[0096] Please see Figure 7 In some embodiments, a second antioxidant protective layer 50 may be provided on the second welding seed layer 41.

[0097] Thus, by setting a second antioxidant protective layer 50 on the second welding seed layer 41, the second antioxidant protective layer 50 can protect the second welding seed layer 41, effectively preventing the second welding seed layer 41 from being exposed to the air for a long time to generate oxides, which would lead to a deterioration in welding performance. At the same time, it can also prevent the appearance of organic matter, dust and other impurities from adhering to the surface of both layers.

[0098] In some embodiments, the thickness of the second welding seed layer 41 may be 60nm-150nm.

[0099] Thus, by setting the thickness of the second welding seed layer 41 within this reasonable range, it is possible to effectively avoid the second welding seed layer 41 being too thin and unable to form a stable weld with the welding strip, thus ensuring stability and reliability. At the same time, it is also possible to avoid the second welding seed layer 41 being too thick, which would lead to a significant increase in cost.

[0100] Specifically, in such an embodiment, the thickness of the second welding seed layer 41 can be, for example, any value between 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm, 105nm, 110nm, 115nm, 120nm, 125nm, 130nm, 135nm, 140nm, 145nm, 150nm, or 60nm-150nm, and is not limited herein.

[0101] In such an embodiment, the thickness of the second welding seed layer 41 is preferably 80nm-120nm. Specifically, through research and verification by the inventors of this application, it has been found that when the thickness of the second welding seed layer 41 is less than 80nm, although it can form a weld with the solder strip, it is easily susceptible to unstable welding under the influence of external forces. Conversely, if the thickness of the second welding seed layer 41 is greater than 120nm, the cost will increase significantly. After research, the inventors of this application have set the thickness of the second welding seed layer 41 within the preferred range of 80nm-120nm, which can reduce costs while maximizing welding stability and reliability.

[0102] It is understood that in this application, the second welding seed layer 41 serves the function of welding and collecting charge carriers, and it needs to be fabricated using a relatively active metal seed layer, such as the seed copper layer mentioned above. However, highly active metal seed layers are prone to oxidation, which leads to a deterioration in subsequent welding performance. Therefore, this application effectively avoids this situation by providing a second anti-oxidation protective layer 50 on the second welding seed layer 41.

[0103] Specifically, in such embodiments, the second welding seed layer 41 can be a highly active metal layer, such as a seed copper layer, while the second anti-oxidation protective layer 50 can be an inert metal layer. For example, in some embodiments, the second anti-oxidation protective layer 50 can be at least one of a tin layer, a nickel layer, and a metal oxide layer, and it can also be formed on the second welding seed layer 41 by PVD deposition, inkjet printing, or other methods. Alternatively, it can be formed by heat treatment.

[0104] Of course, in other embodiments, the second antioxidant protective layer 50 may also be an organic or inorganic film layer capable of resisting oxidation, such as an inorganic film layer with a chain structure. The specific type is not limited here, but an inert metal layer is preferred.

[0105] In some embodiments, the second antioxidant protective layer 50 may also be a magnetic layer, so that the second antioxidant protective layer 50 can generate a magnetic attraction force on the solder ribbon. In this way, during the welding process with the solder ribbon, the second antioxidant protective layer 50 can attract the solder ribbon, which can effectively prevent the solder ribbon from shifting during the welding process, improve the stability and reliability of the welding. That is to say, the second antioxidant protective layer 50 can not only effectively prevent the second welding seed layer 41 from oxidizing, but also position and pre-fix the solder ribbon during the welding process.

[0106] Specifically, in such embodiments, the magnetic layer refers to a film layer that has magnetic adsorption function itself or a film layer that has magnetic adsorption function after being energized. The magnetic layer can be made entirely of magnetic materials.

[0107] Of course, it is understood that in some embodiments, the second antioxidant protective layer 50 may not be a magnetic layer made entirely of magnetic materials, but may contain magnetic material components. For example, magnetic materials may be added to inert metal layers such as tin layer, nickel layer and metal oxide layer as described above, so that the second antioxidant protective layer 50 can generate magnetic attraction to the solder ribbon.

[0108] In addition, some metal particles may be spattered during the welding process. The magnetic attraction can be used to attract some of these metal particles, thereby reducing surface contamination of the solar cells, improving the light absorption capacity of the solar cells, and increasing the light conversion efficiency of the solar cells.

[0109] It is easy to understand that the second antioxidant protective layer 50 will melt and flow during the welding process. Therefore, in the final battery string 200 and battery assembly 300, there may be a phenomenon where the second antioxidant protective layer 50 is not present between some or all areas of the second welding seed layer 41 and the welding strip.

[0110] In some embodiments, the thickness of the second antioxidant protective layer 50 can be 50 nm to 20 μm. Setting the thickness of the antioxidant film layer within this reasonable range avoids both insufficient anti-oxidation effect due to excessive thickness and significant cost increase due to excessive thickness.

[0111] Specifically, the thickness of the second antioxidant protective layer 50 can be, for example, any value between 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 70nm, 800nm, 900nm, 1um, 1um, 2um, 3um, 4um, 5um, 6um, 7um, 8um, 9um, 10um, 11um, 12um, 13um, 14um, 15um, 16um, 17um, 18um, 19um, 20um, or 50nm-20um, without any specific limitation.

[0112] In some embodiments, the second welding seed layer 41 may contain a magnetic material to enable it to generate a magnetic attraction force on the solder ribbon. Thus, during the welding process, the second welding seed layer 41 can also attract the solder ribbon, effectively preventing ribbon misalignment during welding and improving welding stability and reliability.

[0113] Of course, it should be noted that in other embodiments, the current collection structure 40 located on the second transparent conductive film 18 can also be an electrode structure formed by conventional printing silver paste or electroplating copper process. There is no specific limitation here. It is only necessary that during the formation of the battery string 200, the first solder strip 210 of the previous one is connected and conductive to the current collection structure 40 of the next one between two adjacent HJT solar cells 100.

[0114] Please see Figure 8 In some embodiments, in the battery string 200, when the current harvesting structure 40 includes a plurality of second welding seed layers 41 formed on the second transparent conductive film 18 and spaced apart along a first direction, the first solder strip 210 on the Nth HJT solar cell 100 bends and extends towards the side where the second welding seed layer 41 of the N+1th HJT solar cell 100 is located at the interval between two adjacent HJT solar cells 100 and is welded to the second welding seed layer 41. Specifically, in such a case, each second welding seed layer 41 may be correspondingly connected to one first solder strip 210.

[0115] In this way, two adjacent HJT solar cells 100 in the battery string 200 can be directly connected in series by bending the first solder strip 210 to achieve current output.

[0116] Please continue reading. Figure 8In some embodiments, the first solder strip 210 may include a first straight portion 211, a bent portion 212, and a second straight portion 213. The first straight portion 211 is parallel to and welded to the first solder seed layer 20 of the Nth HJT solar cell 100. The bent portion 212 is located at the interval between two adjacent HJT solar cells 100. The second straight portion 213 is parallel to and welded to the second solder seed layer 41 of the N+1th HJT solar cell 100. It should be noted that "parallel coverage" refers to two components being arranged in parallel, with one component completely covering the other component.

[0117] Thus, a flexible first solder strip 210 can be used to connect the first solder seed layer 20 of the preceding cell and the second solder seed layer 41 of the following cell, thereby achieving series connection between cells. Specifically, as shown... Figure 8 As shown, in such an embodiment, the first solder strip 210 is generally Z-shaped.

[0118] Please see Figure 8 In some embodiments, the battery string 200 includes at least one end battery piece 110 located at one end of the battery string 200, and the second solder seed layer 41 on the end battery piece 110 is not covered by the first solder strip 210. In such cases, the battery string 200 may also include a second solder strip 220 disposed on and soldered to the second solder seed layer 41 of the end battery piece 110.

[0119] Thus, by providing a second solder strip 220 on the second solder seed layer 41 of the end cell 110, the second solder strip 220 can be used as the connection end of the cell string 200 and welded to the busbar when forming the assembly.

[0120] Specifically, in some embodiments, one output end of the battery string 200 is a first solder strip 210, and the other output end is a second solder strip 220. In this case, only one end battery cell 110 needs to have the second solder strip 220. Of course, in one possible embodiment, both output ends of the battery string 200 can be the second solder strip 220. In this case, the battery string 200 has two end battery cells 110.

[0121] Please see Figure 9In some embodiments, the current harvesting structure 40 may include a plurality of second welding seed layers 41 formed on the second transparent conductive film 18 and spaced apart along a first direction. In such cases, in some embodiments, the battery string 200 may further include a third solder strip 230 disposed on and welded to the second welding seed layers 41 and a conductive connector 240 disposed at the interval between two adjacent HJT solar cells 100, wherein each second welding seed layer 41 is correspondingly welded with a third solder strip 230, and the conductive connector 240 is connected to the first solder strip 210 on the Nth HJT solar cell 100 and the third solder strip 230 on the N+1th HJT solar cell 100.

[0122] In this embodiment, the difference from the embodiments mentioned above is that, in this embodiment, the first solder strip 210 and the third solder strip 230 are directly soldered on the first solder seed layer 20 and the second solder seed layer 41, respectively. During the formation of the battery string 200, the first solder strip 210 and the third solder strip 230 on the adjacent two battery cells are connected by setting a conductive connector 240 between the adjacent two battery cells, thereby realizing the series connection between the battery cells.

[0123] In the description of this specification, references to terms such as "some embodiments," "illustrative embodiments," "exemplary," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with the described embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0124] Furthermore, the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An HJT solar cell, characterized in that, include: A silicon wafer having opposing first and second surfaces; A first intrinsic amorphous silicon layer, a first doped amorphous silicon layer, and a first transparent conductive film are sequentially stacked on the first surface; A second intrinsic amorphous silicon layer, a second doped amorphous silicon layer, and a second transparent conductive film are sequentially stacked on the second surface; A plurality of first welding seed layers are disposed on the first transparent conductive film, the plurality of first welding seed layers are arranged at intervals along a first direction, and the first welding seed layers all extend along a second direction, the second direction intersecting the first direction; the first welding seed layers are used to weld to the welding strip located above and covering the first welding seed layer. A first antioxidant protective layer is disposed on the first welding seed layer; and A current collection structure disposed on the second transparent conductive film.

2. The HJT solar cell according to claim 1, characterized in that, The first solder seed layer includes a seed copper layer; and / or The first antioxidant protective layer includes at least one of a tin layer, a nickel layer, and a metal oxide layer.

3. The HJT solar cell according to claim 1, characterized in that, The first antioxidant protective layer includes at least one of a tin layer, a nickel layer, and a metal oxide layer.

4. The HJT solar cell according to claim 1, characterized in that, The first antioxidant protective layer is a magnetic layer or contains magnetic material, so that the first antioxidant protective layer can generate a magnetic attraction force on the solder ribbon.

5. The HJT solar cell according to claim 1, characterized in that, The thickness of the first welding seed layer is 60nm-150nm; and / or The thickness of the first antioxidant protective layer is 50nm-20um.

6. The HJT solar cell according to claim 1, characterized in that, The first welding seed layer contains a magnetic material so that it can generate a magnetic attraction force on the welding strip.

7. The HJT solar cell according to claim 1, characterized in that, The current collection structure includes a plurality of second welding seed layers, which are also arranged at intervals along the first direction, and all the second welding seed layers extend along the second direction. The second welding seed layer is used for welding to the welding strip located above and covering the second welding seed layer.

8. The HJT solar cell according to claim 7, characterized in that, The thickness of the second welding seed layer is 60nm-150nm.

9. The HJT solar cell according to claim 7, characterized in that, A second antioxidant protective layer is provided on the second welding seed layer.

10. The HJT solar cell according to claim 9, characterized in that, The second antioxidant protective layer includes at least one of a tin layer, a nickel layer, and a metal oxide layer.

11. The HJT solar cell according to claim 9, characterized in that, The second antioxidant protective layer is a magnetic layer or contains magnetic material, so that the second antioxidant protective layer can generate a magnetic attraction force on the solder ribbon.

12. The HJT solar cell according to claim 9, characterized in that, The thickness of the second antioxidant protective layer is 50nm-20um.

13. The HJT solar cell according to claim 7, characterized in that, The second welding seed layer contains a magnetic material so that it can generate a magnetic attraction force on the welding strip.

14. A battery string, characterized in that, include: The HJT solar cell according to any one of claims 1-13, wherein the plurality of HJT solar cells are arranged at intervals along the second direction, and all the HJT solar cells are oriented in the same direction; and A first solder strip is disposed on the first welding seed layer, the first solder strip covers the first welding seed layer and is welded to the first welding seed layer; Wherein, the first solder strip on the Nth HJT solar cell is electrically connected to the current collection structure of the (N+1)th HJT solar cell, where N is a positive integer.

15. The battery string according to claim 14, characterized in that, The current harvesting structure includes a plurality of second welding seed layers formed on the second transparent conductive film and spaced apart along the first direction; In this case, the first solder strip on the Nth HJT solar cell bends and extends towards the side where the second solder seed layer of the N+1th HJT solar cell is located at the interval between two adjacent HJT solar cells and is soldered to the second solder seed layer.

16. The battery string according to claim 15, characterized in that, The first solder strip includes a first straight portion, a bent portion, and a second straight portion. The first straight portion is parallel to and covers the first solder seed layer of the Nth HJT solar cell and is soldered to the first solder seed layer. The bent portion is located in the interval area between two adjacent HJT solar cells. The second straight portion is parallel to and covers the second solder seed layer of the N+1th HJT solar cell and is soldered to the second solder seed layer.

17. The battery string according to claim 15, characterized in that, The battery string includes at least one end battery cell located at the end of the battery string, wherein the first solder strip is not covered on the second solder seed layer on the end battery cell; the battery string also includes a second solder strip disposed on the second solder seed layer of the end battery cell and soldered to the second solder seed layer.

18. The battery string according to claim 14, characterized in that, The current harvesting structure includes a plurality of second welding seed layers formed on the second transparent conductive film and spaced apart along the first direction; The battery string also includes a third solder strip disposed on and welded to the second solder seed layer, and a conductive connector disposed in the interval area between two adjacent HJT solar cells. The conductive connector is connected to the first solder strip on the Nth HJT solar cell and the third solder strip on the N+1th HJT solar cell.

19. A battery assembly, characterized in that, Includes the battery string according to any one of claims 14-18.

20. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 19.

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