Solar cell, cell module and photovoltaic system

Abstract

The invention is applicable to the field of photovoltaic technology, and provides a solar cell, a cell module and a photovoltaic system, and the solar cell comprises a first surface and a second surface which are opposite to each other; a plurality of side surfaces connected between the first surface and the second surface, the plurality of side surfaces including a cut side surface and a non-cut side surface; the third passivation layer extends to the non-cutting side surface in the circumferential direction of the solar cell, the third passivation layer covers the fourth passivation layer, and the third passivation layer is of a continuous film layer structure. According to the solar cell, the cutting side surface and the non-cutting side surface in the multiple side surfaces are passivated, surface defects are reduced, and the yield of the solar cell is improved. And the third passivation layer formed on the cutting side surface extends to the non-cutting side surface and covers the fourth passivation layer, so that the damage of the passivation layer on the non-cutting side surface in the manufacturing process can be made up, and the overall photoelectric conversion efficiency of the battery piece is further improved.

Description

Technical Field

[0001] The present application belongs to the field of photovoltaic technology, and in particular relates to a solar cell, a battery assembly and a photovoltaic system. Background Art

[0002] A solar cell is a device that utilizes solar energy and directly converts light energy into electrical energy through the photoelectric effect or the photochemical effect. Solar cells include sliced ​​solar cells. Currently, the production of sliced ​​solar cells usually involves cutting solar cells that have already formed multiple film layers to cut the entire solar cell into at least two sliced ​​solar cells, such as two halves. Afterwards, the sliced ​​solar cells are used to make photovoltaic modules. However, after cutting, the cut surfaces of the sliced ​​solar cells have laser damage and interface defects. These damages and defects become effective recombination centers for carriers. The existing passivation film layer on the non-cut side surface is also easily damaged during the manufacturing process, which can also cause recombination losses of carriers, thereby reducing the efficiency of the solar cell.

[0003] Application Contents

[0004] The present application provides a solar cell, aiming to solve the problem of laser damage and interface defects on the cut surface of the sliced ​​solar cell. These damages and defects become effective recombination centers for carriers. The existing passivation film layer on the non-cut side surface is also easily damaged during the manufacturing process, which will also cause carrier recombination losses, thereby reducing the efficiency of the solar cell.

[0005] The present application is implemented as follows: a solar cell, the solar cell comprising a first surface and a second surface opposite to each other; a plurality of side surfaces connected between the first surface and the second surface, the plurality of side surfaces comprising a cut side surface and a non-cut side surface; a fourth passivation layer, the fourth passivation layer being formed on the non-cut side surface; a third passivation layer, the third passivation layer being formed on the cut side surface, the third passivation layer extending to the non-cut side surface in the circumferential direction of the solar cell, the third passivation layer covering the fourth passivation layer, the third passivation layer being a continuous film layer structure.

[0006] Optionally, the third passivation layer includes a first aluminum oxide film layer.

[0007] Optionally, the thickness of the first aluminum oxide film layer is 20-200 nm.

[0008] Optionally, the fourth passivation layer includes a multilayer film structure, and the fourth passivation layer includes at least a second aluminum oxide film layer and a silicon nitride film layer stacked together, the second aluminum oxide film layer covers the non-cut side surface, and the silicon nitride film layer covers the second aluminum oxide film layer.

[0009] Optionally, the second aluminum oxide film layer has a thickness of 1-10 nm.

[0010] Optionally, the thickness of the silicon nitride film layer is 1-300 nm.

[0011] Optionally, the fourth passivation layer further includes a silicon oxide film layer, and the silicon oxide film layer covers the silicon nitride film layer.

[0012] Optionally, the thickness of the silicon oxide film layer is 1-200 nm.

[0013] Optionally, the method further includes a first passivation layer disposed on the first surface and a second passivation layer disposed on the second surface.

[0014] Optionally, the thickness of the first passivation layer is 10-200 nm.

[0015] Optionally, the second passivation layer has a thickness of 10-200 nm.

[0016] Optionally, the third passivation layer has a first portion extending to the first surface and a second portion extending to the second surface, the first portion covers the first passivation layer, and the second portion covers the second passivation layer.

[0017] The present application passivates the cut side surfaces and non-cut side surfaces among multiple side surfaces to reduce surface defects and reduce the recombination of carriers on the side surfaces. The third passivation layer formed on the cut side surfaces extends to the non-cut side surfaces. The third passivation layer covers the fourth passivation layer on the non-cut side surfaces, which can compensate for the damage to the passivation layer on the non-cut side surfaces during the manufacturing process, thereby improving the overall photoelectric conversion efficiency of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The structure of the solar cell provided in the present application is shown in FIG. Figure 1 ;

[0019] Figure 2 The structure of the solar cell provided in the present application is shown in FIG. Figure 2 ;

[0020] Figure 3 It is a schematic structural diagram of the fourth passivation layer of the solar cell provided in the present application.

[0021] Description of reference numerals:

[0022] 100, first surface; 200, second surface; 300, side surface; 301, cut side surface; 302, non-cut side surface; 400, third passivation layer; 401, first part; 402, second part; 403, first aluminum oxide film layer; 500, first passivation layer; 600, second passivation layer; 700, fourth passivation layer; 701, second aluminum oxide film layer; 702, silicon nitride film layer; 703, silicon oxide film layer. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below 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 throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0024] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are 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 therefore should not be understood as a limitation on the present application.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0026] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0027] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0028] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0029] like Figure 1 and Figure 2 As shown, in the embodiment of the present application, the solar cell includes a first surface 100 and a second surface 200 relative to each other; and a plurality of side surfaces 300 connected between the first surface 100 and the second surface 200. For example, in the embodiment of the present application, the first surface 100 is a light-facing surface, and the second surface 200 is a backlight surface. Of course, in other embodiments, the first surface 100 may be a backlight surface, and the second surface 200 may be a light-facing surface, and the present application does not limit this. The solar cell may be a bifacial solar cell or a back contact solar cell. The solar cell may be a perc cell, a topcon cell, a TBC cell or a heterojunction solar cell. Of course, the solar cell may also be a solar cell including a tunnel passivation structure or other types of solar cells including a heterojunction structure.

[0030] The multiple side surfaces 300 include a cutting side surface 301 and a non-cutting side surface 302. The non-cutting side surface 302 is the initial side surface of the entire cell. Before the cell is sliced, the outer surface of the cell has been initially passivated, and an initial passivation film layer is formed on the initial side surface of the cell. The cutting side surface 301 is the exposed side surface 300 formed after the entire cell is sliced. It should be noted that in the cell slicing process, the first side 100 or the second side 200 of the cell is damaged to a certain extent through direct external action, and then the entire solar cell is broken through stress changes, thereby forming a complete cutting side surface 301. The cutting side surface 301 usually inevitably has surface defects and damages, and these damages and defects become effective recombination centers for carriers, thereby affecting the power generation efficiency of the cell.

[0031] In the embodiment of the present application, the fourth passivation layer 700 is formed on the non-cut side surface 302, and the fourth passivation layer 700 is the initial passivation film layer described above. It can be understood that in other embodiments, the fourth passivation layer 700 is not only formed on the non-cut side surface 302, but also can be formed on the first surface 100 and the second surface 200 to achieve effective passivation of the outer surface of the solar cell. The third passivation layer 400 is formed on the cut side surface 301, and the third passivation layer 400 extends to the non-cut side surface 302 in the circumferential direction of the solar cell. The third passivation layer 400 covers the fourth passivation layer 700, and the third passivation layer 400 is a continuous film structure. The third passivation layer 400 is a secondary passivation performed on the cut side surface 301 after the entire cell is sliced. The formed passivation film layer covers the exposed cut side surface 301. At the same time, the present application performs secondary passivation on the non-cut side surface 302 while passivating the cut side surface 301, so that the outside of the initial passivation film layer is covered with another passivation film layer. In this way, on the one hand, a continuous film layer structure is formed between the multiple side surfaces 300 of the cell, and the integrity of the passivation film layer is better. On the other hand, it can compensate for the damage of the initial passivation film layer caused by the process of the non-cut side surface 302, thereby ensuring the integrity and reliability of the passivation film layer on the multiple side surfaces 300 of the cell.

[0032] The present application passivates the cut side surface 301 to reduce defects on the cut side surface 301 and reduce the recombination of carriers on the cut side surface 301, thereby improving the power generation efficiency of the battery cell, and further extends the third passivation layer 400 formed on the cut side surface 301 to the non-cut side surface 302. The third passivation layer 400 covers the fourth passivation layer 700, which can compensate for the damage to the passivation layer on the non-cut side surface 302 during the manufacturing process, thereby improving the overall photoelectric conversion efficiency of the battery cell.

[0033] Furthermore, the distribution of the cutting side surface 301 and the non-cutting side surface 302 is determined according to the slicing method, which is not limited in the present application. The cutting side surface 301 may be one or two. Regardless of the number of cutting side surfaces 301, the cutting side surface 301 will be subjected to secondary passivation after the whole cell is sliced, and the passivation film layer formed by the secondary passivation extends to the non-cutting side surface 302, forming a continuous film layer structure between multiple side surfaces 300, that is, the third passivation layer 400 formed by the secondary passivation covers all the side surfaces 300 of the cell at the same time. Exemplarily, when cutting a whole solar cell, if a whole solar cell is divided into two sliced ​​solar cells along its length, each sliced ​​cell has only one cutting side surface 301. For example, when cutting a whole solar cell, if a whole solar cell is divided into three slice solar cells along its length direction, the three slice cells include a first slice cell, a second slice cell and a third slice cell, then the middle second slice cell has two cutting side surfaces 301, and the first slice cell and the third slice cell each have only one cutting side surface 301.

[0034] In some embodiments, the third passivation layer 400 includes a first aluminum oxide film layer 403, which is directly formed on the cut side surface 301 to improve the protection of the cut side surface 301. In the solar cell, the first aluminum oxide film layer 403 can effectively prevent the conduction of the electric field and current, reduce the recombination loss of the charge inside the cell, and thus improve the photoelectric conversion efficiency of the cell. As a possible implementation, the thickness of the first aluminum oxide film layer 403 is greater than or equal to 20nm and less than or equal to 200nm. For example, the thickness of the first aluminum oxide film layer 403 can be 20nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 100nm, 105nm, 110nm, 115nm, 120nm, 125nm, 130nm, 135nm, 140nm, 145nm, 150nm, 155nm, 160nm, 165nm, 170nm, 175nm, 180nm, 185nm, 190nm, 195nm or 200nm, etc. When the above technical solution is adopted, the passivation effect of the solar cell increases gradually, and the conversion efficiency of the solar cell increases with the increase of the thickness of the first aluminum oxide film layer 403. Furthermore, too thin a thickness of the first aluminum oxide film layer 403 will result in insufficient passivation effect, while too thick a thickness of the first aluminum oxide film layer 403 will reduce the marginal effect of the passivation effect and increase the process time and material consumption.

[0035] like Figure 3As shown, in an optional manner, the fourth passivation layer 700 includes a multilayer film structure, and the fourth passivation layer 700 includes at least a second aluminum oxide film layer 701 and a silicon nitride film layer 702 stacked, the second aluminum oxide film layer 701 covers the non-cut side surface 302, and the silicon nitride film layer 702 covers the second aluminum oxide film layer 701. It can be understood that the fourth passivation layer 700 is a multilayer film structure, and the third passivation layer 400 is arranged at the outermost layer of the multilayer film structure to form protection for the fourth passivation layer 700. The second aluminum oxide film layer 701 is directly formed on the non-cut side surface 302, which is used to protect the non-cut side surface 302, reduce the recombination rate of carriers at the non-cut side surface 302, and further improve the photoelectric conversion efficiency of the solar cell. The silicon nitride film layer 702 can play a role in anti-reflection, which is conducive to refracting more light from the non-cut side surface 302 into the battery cell, so as to further improve the utilization rate of light by the solar cell. Specifically, the thickness of the second aluminum oxide film layer 701 is 1-10 nm. The aluminum oxide film layer has excellent passivation properties and can effectively reduce dangling bonds and defects on the surface of the solar cell. Within the above thickness range, the second aluminum oxide film layer 701 can be tightly covered on the surface of the cell to form a dense passivation layer, thereby reducing the surface recombination rate and increasing the open circuit voltage and short circuit current density of the cell. In addition, within the above thickness range, the second aluminum oxide film layer 701 can form a certain optical interference effect. This interference effect helps to increase the absorption and reflection efficiency of the solar cell to light, so that more light is absorbed by the cell and converted into electrical energy.

[0036] In some embodiments, the thickness of the silicon nitride film layer 702 is 1-300 nm. Exemplarily, the thickness of the silicon nitride film layer 702 can be 1 nm, 10 nm, 30 nm, 40 nm, 60 nm, 70 nm, 85 nm, 100 nm, 150 nm, 200 nm, 300 nm, or any value between 1 and 300 nm, and is not specifically limited here. The silicon nitride film layer 702 has a high refractive index. By selecting the thickness of the silicon nitride film layer 702 to be within the above range, the silicon nitride film layer 702 can effectively reduce reflection and improve the transmittance of light.

[0037] Preferably, the fourth passivation layer 700 also includes a silicon oxide film layer 703, and the silicon oxide film layer 703 covers the silicon nitride film layer 702. By cooperating with the silicon oxide film layer 703 and the silicon nitride film layer 702, the optimization of optical performance can be achieved. For example, in a solar cell, the silicon oxide layer can be used as part of the anti-reflection layer, and work together with the silicon nitride layer to reduce the reflection of light and improve the light absorption efficiency. In addition, the silicon oxide film layer 703 can effectively block the migration and diffusion of charges, thereby protecting the underlying silicon nitride film layer 702 from charge interference and damage. The silicon oxide film layer 703 has good wear resistance and can protect the underlying silicon nitride film layer 702 from wear and scratches, thereby extending the service life of the entire passivation film layer. Preferably, the thickness of the silicon oxide film layer 703 is 1-200nm. For example, the thickness of the silicon nitride film layer 702 can be 1 nm, 10 nm, 30 nm, 40 nm, 60 nm, 70 nm, 85 nm, 100 nm, 150 nm, 200 nm or any value between 1 and 200 nm, and is not limited here. The silicon oxide film layer 703 serves as an outer protective layer. The thickness of the silicon oxide film layer 703 has high hardness and mechanical strength within this range, and can withstand large external forces without being easily broken or deformed.

[0038] In some embodiments, the first surface 100 is provided with a first passivation layer 500, and the second surface 200 is provided with a second passivation layer 600. The first passivation layer 500 and the second passivation layer 600 may have the same film structure as the fourth passivation layer, or the first passivation layer 500 and the second passivation layer 600 may have a different film structure from the fourth passivation layer. The third passivation layer 400 has a first portion 401 extending to the first surface 100, and the first portion 401 covers the first passivation layer 500. The third passivation layer 400 also has a second portion 402 extending to the second surface 200, and the second portion 402 covers the second passivation layer 600. In this way, the edge portion of the battery cell can be covered, and the edge portion of the battery cell has a film structure consistent with the first surface 100 and the second surface 200, and the edge portion can be efficiently passivated, thereby reducing the recombination of the edge portion and improving the conversion efficiency of the solar cell. In addition, the first portion 401 of the third passivation layer 400 extending to the first surface 100 and the first passivation layer 500 can form a double passivation mechanism together, and the second portion 402 of the third passivation layer 400 extending to the second surface 200 and the second passivation layer 600 can form a double passivation mechanism together. This double passivation mechanism can greatly reduce the number of carriers of one polarity reaching the surface, thereby significantly reducing the recombination loss on the substrate surface and improving the performance of the battery cell. Further, the thickness of the first passivation layer 500 is 10 to 200 nm. For example, the thickness of the first passivation layer 500 can be 10 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 90 nm, 100 nm, 120 nm, 125 nm, 140 nm, 150 nm, 170 nm, 175 nm, 180 nm, 190 nm, 195 nm or 200 nm, etc. The thickness of the first passivation layer 500 within this range can ensure the passivation quality of the first surface 100 and reduce the recombination loss of carriers on the first surface 100. Further, the thickness of the second passivation layer 600 is 10 to 200 nm. For example, the thickness of the second passivation layer 600 can be 10 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 90 nm, 100 nm, 120 nm, 125 nm, 140 nm, 150 nm, 170 nm, 175 nm, 180 nm, 190 nm, 195 nm or 200 nm. The thickness of the second passivation layer 600 within this range can ensure the passivation quality of the second surface 200 and reduce the recombination loss of carriers on the second surface 200.

[0039] In other embodiments, the thickness of the second portion 402 is greater than the thickness of the first portion 401. Since the backlight surface is in contact with the metal electrode, charge recombination is more likely to occur, so increasing the thickness of the passivation film extending from the third passivation layer 400 to the backlight surface can more effectively prevent charge recombination, improve the photoelectric conversion efficiency of the battery, and provide stronger protection for the backlight surface of the battery cell to prevent damage to the battery cell by the external environment, such as oxidation, corrosion, etc., which helps to extend the service life of the battery cell.

[0040] The photovoltaic system in the embodiment of the present application may include the battery assembly in the embodiment of the present application, and the battery assembly in the embodiment of the present application may include several solar cells in the embodiment of the present application. Of course, the battery assembly may also include a backplane and a glass plate. A plurality of battery cells are arranged between the backplane and the glass plate, and a welding strip (bus bar, interconnection strip), a conductive backplane, etc. are provided on the battery cell to realize the series connection of the battery cells.

[0041] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0042] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A solar cell, characterized in that: The solar cell comprises a first surface and a second surface opposite to each other; a plurality of side surfaces connected between the first surface and the second surface, the plurality of side surfaces comprising a cut side surface and a non-cut side surface; a fourth passivation layer, the fourth passivation layer being formed on the non-cutting side surface; A third passivation layer is formed on the cut side surface, the third passivation layer extends to the non-cut side surface in the circumferential direction of the solar cell, the third passivation layer covers the fourth passivation layer, and the third passivation layer is a continuous film layer structure.

2. The solar cell according to claim 1, wherein: The third passivation layer includes a first aluminum oxide film layer.

3. The solar cell according to claim 2, characterized in that The thickness of the first aluminum oxide film layer is 20-200 nm.

4. The solar cell according to claim 1, wherein: The fourth passivation layer includes a multi-layer film structure, and the fourth passivation layer at least includes a second aluminum oxide film layer and a silicon nitride film layer stacked together, the second aluminum oxide film layer covers the non-cut side surface, and the silicon nitride film layer covers the second aluminum oxide film layer.

5. The solar cell according to claim 4, characterized in that The thickness of the second aluminum oxide film layer is 1-10 nm.

6. The solar cell according to claim 4, characterized in that The thickness of the silicon nitride film layer is 1-300 nm.

7. The solar cell according to claim 4, characterized in that The fourth passivation layer further includes a silicon oxide film layer, and the silicon oxide film layer covers the silicon nitride film layer.

8. The solar cell according to claim 7, wherein: The thickness of the silicon oxide film layer is 1-200 nm.

9. The solar cell according to claim 1, wherein: The invention also includes a first passivation layer disposed on the first surface and a second passivation layer disposed on the second surface.

10. The solar cell according to claim 9, characterized in that The thickness of the first passivation layer is 10-200 nm.

11. The solar cell according to claim 9, wherein: The thickness of the second passivation layer is 10-200 nm.

12. The solar cell according to claim 9, wherein: The third passivation layer has a first portion extending to the first surface and a second portion extending to the second surface, the first portion covers the first passivation layer, and the second portion covers the second passivation layer.

13. A battery assembly, characterized in that: Comprising the solar cell according to any one of claims 1 to 12.

14. A photovoltaic system, characterized in that: Comprising the battery assembly as claimed in claim 13.

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