A solar cell, a module structure and a method for preparing the same

Abstract

The invention discloses a solar cell, a component structure and a preparation method thereof, belonging to the technical field of solar cell manufacturing, comprising a blue film, a metal electrode and a welding strip, wherein the blue film comprises a front side and a back side, and there is no metal grid line on the front side and the back side, and a metal electrode with an opening on the front side, a transparent conductive film on the front side, an N-type doped hydrogenated amorphous silicon layer, a front intrinsic hydrogenated amorphous silicon layer, a crystalline silicon layer, a back intrinsic hydrogenated amorphous silicon layer, a P-type doped hydrogenated amorphous silicon layer, a transparent conductive film on the back side, and a metal electrode with an opening on the back side are sequentially arranged between the front side and the back side of the solar cell. A welding strip is arranged at the opening position of the metal electrode, and the high temperature during the lamination process is used to ensure that the low-temperature alloy coating on the surface of the welding strip is melted, and the gap between the metal welding strip and the opening of the battery metal electrode is filled, so as to increase the contact area between the welding strip and the metal electrode, increase the bonding between the welding strip and the metal electrode, improve the reliability, increase the contact area between the welding strip and the fine grid line, reduce the contact resistance, and solve the risk of poor welding that is easy to occur in the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cell manufacturing, and in particular relates to a solar cell, a component structure and a preparation method thereof. Background Art

[0002] With the development of economy and society, the extensive use of conventional fossil energy has led to serious environmental pollution problems. The development and utilization of clean energy has become a consensus among people. Since solar energy is inexhaustible, clean and pollution-free, it is the most ideal and sustainable renewable energy in the future. Solar cells directly convert light energy into electrical energy, which is an important way to utilize solar energy. Conventional solar cell modules use welding ribbons to interconnect the positive and negative electrodes of solar cell sheets with sizes of 156.75cm×156.75cm or 125cm×125cm to form a power generation unit device with a certain current and voltage output. However, this welding interconnection method generally requires welding at a high temperature of more than 200°C. The commonly used welding ribbon is a copper ribbon coated with tin alloy. The thermal expansion coefficient of copper is 7 times that of crystalline silicon. During the cooling process after high-temperature welding, the difference in thermal expansion coefficient will cause the solar cell to bend, and the thinner the solar cell, the more serious the bending. The larger the bending, the more stress concentration inside the solar cell, resulting in an increase in the fragmentation rate of the solar cell. At the same time, the bending will also cause a false solder joint between the solar cell and the welding ribbon. At the same time, the commonly used solder strips on the 156.75cm×156.75cm battery cell are mostly 1.2mm×0.23mm or 0.9mm×0.25mm in size. Such wide solder strips covering the surface of the battery cell seriously block the light-receiving area of ​​the battery cell, affecting the conversion efficiency of the battery cell and the final output power of the component.

[0003] In order to overcome the light blocking by the welding ribbon and reduce the transmission loss of current on the fine grid lines, people invented multi-busbar and busbar-free cells, that is, the number of busbars on the surface of conventional solar cells is increased and the width is reduced, while busbar-free cells completely remove the busbars. When preparing components for busbar-free cells, low-temperature coated welding ribbons, usually SnPbBi or SnBiAg alloys, are used to press on the fine grid lines of the cell. Then, by heating, the welding ribbons melt and bond with the fine grid lines to form contact points between the cell and the welding ribbons, which play the role of current output. Currently, the commonly used busbar-free low-temperature coated welding ribbons are mostly cylindrical, which results in point contact between the cylinder and the fine grid lines, and the contact area is very small. At the same time, due to the unevenness of the fine grid lines and welding ribbons, the contact points often have a phenomenon of cold soldering, which affects the fill factor and final output power of the component. At the same time, the small solder joints also reduce the reliability of the component.

[0004] Therefore, how to provide a new solar cell module structure and its manufacturing method to reduce the risk of cold soldering at the contact points between the cylindrical welding strip and the fine grid wire and increase the output power and reliability of the solar module has become an important technical problem that needs to be solved urgently by technical personnel in this field. Summary of the invention

[0005] The purpose of the present invention is to provide a solar cell module structure and a method for manufacturing the same, so as to solve the problems in the prior art of small contact area between cylindrical welding strip and fine grid line, increased series resistance, greater risk of cold welding and poor reliability.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A solar cell structure includes a blue film and a metal electrode. The blue film has no metal electrode grid lines on the front and back sides. A front transparent conductive film, an N-type doped hydrogenated amorphous silicon layer, a front intrinsic hydrogenated amorphous silicon layer, a crystalline silicon layer, a back intrinsic hydrogenated amorphous silicon layer, a P-type doped hydrogenated amorphous silicon layer, and a back transparent conductive film are sequentially arranged between the front and back sides. The solar cell is provided with a metal electrode with an opening on the front side and a metal electrode with an opening on the back side. The metal electrode includes a thin grid line and a wide grid line. The metal electrode is reserved with an opening at the wide grid line position and is widened.

[0008] A solar cell module structure comprises a front side and a back side, wherein a front side metal electrode with an opening, a front side transparent conductive film, an N-type doped hydrogenated amorphous silicon layer, a front side intrinsic hydrogenated amorphous silicon layer, a crystalline silicon layer, a back side intrinsic hydrogenated amorphous silicon layer, a P-type doped hydrogenated amorphous silicon layer, a back side transparent conductive film, and a back side metal electrode with an opening are sequentially arranged between the front side and the back side, wherein metal electrodes are arranged on both the front side and the back side, wherein the metal electrodes comprise thin grid lines and wide grid lines, wherein openings are reserved at the positions of the wide grid lines and are widened, wherein metal welding strips are arranged in the reserved openings of the wide grid lines on the front side and the back side, and wherein the metal welding strips connect the front side of a previous sub-cell with the back side of a subsequent sub-cell.

[0009] A method for preparing a solar cell assembly comprises the following steps:

[0010] S1: preparing a blue film sheet for a solar cell, wherein the front and back sides of the blue film sheet have no metal grid lines;

[0011] S2: forming metal electrodes on the back and front of the solar cell, the metal electrodes are composed of thin grid lines and wide grid lines, and the metal electrodes reserve openings of a certain width at the positions of the wide grid lines;

[0012] S3: Lay the component encapsulation glass and encapsulation film, position and place the metal welding tape on the encapsulation film, place the battery cell with an open metal electrode on the metal welding tape, the opening position of the metal electrode corresponds to the metal welding tape, place the metal welding tape on the surface of the battery cell, the welding tape is placed at the opening position of the metal electrode of the battery cell, and then place the encapsulation film and the backplane;

[0013] S4: placing the laid stack in a laminator, heating and pressurizing, and laminating to prepare an assembly.

[0014] In a further preferred embodiment of the present invention, the opening size is greater than or equal to the diameter or width of the metal welding strip used in the component, and the shape of the opening includes arc, rectangle, trapezoid, and polygon.

[0015] In a further preferred embodiment of the present invention, the metal welding strip is a copper strip coated with a low-temperature alloy coating, and the cross-sectional shape of the metal welding strip includes arc, rectangle, trapezoid, and polygon.

[0016] In a further preferred embodiment of the present invention, the metal welding strip used is a highly conductive material, including Ag, Cu, Ni, Al and alloys thereof.

[0017] In a further preferred embodiment of the present invention, the metal electrode of the solar cell is prepared by screen printing, electroplating or inkjet printing.

[0018] In a further preferred embodiment of the present invention, the width of the wide gate line is 1-10 times the width of the thin gate line.

[0019] In a further preferred embodiment of the present invention, the metal welding strip is a copper strip coated with a low-temperature alloy, and the low-temperature alloy includes tin-lead-bismuth or tin-bismuth-silver, and the alloy has a melting point of 50-200°C.

[0020] In a further preferred embodiment of the present invention, the stack is laminated in a laminator, and the lamination temperature is greater than the melting point of the low-temperature solder strip, so as to melt the solder strip alloy and fill the metal electrode opening with the molten alloy to increase the contact area and improve reliability.

[0021] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0022] The present invention firstly reserves an opening at the welding strip position during the preparation process of the metal electrode of the solar cell sheet, and the width of the metal grid line opening position is greater than the width of the thin grid line. During the preparation process of the component, the welding strip is placed inside the opening, and the lamination process ensures that the low-temperature alloy coating on the surface of the welding strip is melted, filling the gap between the metal welding strip and the opening of the battery metal electrode, increasing the contact area between the welding strip and the metal electrode, increasing the adhesion between the welding strip and the metal electrode, and improving reliability. Compared with the prior art, the present invention has a simple structure, increases the contact area with the thin grid line, reduces the resistance, and solves the risk of cold solder joints that are easy to occur in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0024] Figure 1 It is a schematic diagram of the structure of the present invention;

[0025] Figure 2 It is a schematic diagram of forming a metal gate electrode structure with a certain width opening according to the present invention;

[0026] Figure 3 It is a top view of a metal gate electrode structure having an opening of a certain width formed in the present invention;

[0027] Figure 4 It is a schematic diagram of the solar cell grid electrode structure after placing a welding strip at the metal grid opening of the present invention;

[0028] Figure 5 The top view of the solar cell grid electrode structure after placing a welding strip at the metal grid opening of the present invention

[0029] Figure 6 It is a process flow chart of the present invention;

[0030] Figure numerals: 100-blue film layer stacking structure, 101-front transparent conductive film, 102-N-type doped hydrogenated amorphous silicon layer, 103-front intrinsic hydrogenated amorphous silicon layer, 104-crystalline silicon layer, 105-back intrinsic hydrogenated amorphous silicon layer, 106-P-type doped hydrogenated amorphous silicon layer, 107-back transparent conductive film, 108-front metal electrode with opening, 108a-front metal electrode fine grid line, 108b-front metal electrode and widened contact area with welding strip, 109-back metal electrode with opening, 110-metal grid line opening, 111-circular welding strip. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments, and all features disclosed in this specification, or all steps in the disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

[0032] It should be noted that the directions or positional relationships indicated by terms such as “length”, “width”, “height”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “head” and “tail” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0034] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0035] Combine the following Figure 1-6 The present invention is described in detail.

[0036] Implementation Case 1: A solar cell structure includes a blue film and a metal electrode, the blue film includes a front side and a back side, both of which have no metal grid lines, and a front side metal electrode 108 with an opening, a front side transparent conductive film 101, an N-type doped hydrogenated amorphous silicon layer 102, a front side intrinsic hydrogenated amorphous silicon layer 103, a crystalline silicon layer 104, a back side intrinsic hydrogenated amorphous silicon layer 105, a P-type doped hydrogenated amorphous silicon layer 106, a back side transparent conductive film 107, and a back side metal electrode 109 with an opening are sequentially arranged between the front side and the back side;

[0037] Step 1: The 180 μm thick silicon wafer is subjected to a texturing and cleaning treatment, and the thickness of the silicon wafer after the treatment is 150 μm, and then it is dried in a spin dryer;

[0038] Step 2: Place the silicon wafer in a tray, and prepare an intrinsic hydrogenated amorphous silicon layer α-Si: H(i) and a phosphorus-doped hydrogenated amorphous silicon layer α-Si: H(n) in an ion enhanced chemical vapor deposition (PECVD) device; then turn the silicon wafer over and cover it in the PECVD device to prepare an intrinsic hydrogenated amorphous silicon layer α-Si: H(i) and a boron-doped hydrogenated amorphous silicon layer α-Si: H(p).

[0039] Step 3: Place the silicon wafer with the prepared amorphous silicon layer into a reactive plasma deposition (RPD) device to deposit an 80nm thick transparent conductive oxide film (TCO) on the N side; after the N side TCO deposition is completed, deposit an 80nm thick TCO film on the P side.

[0040] Step 4: Use low-temperature Ag paste to prepare Ag electrodes (positive electrode and back electrode) on the cell with TCO film deposited on it on a screen printer. The fine grid line width of the screen pattern is 0.05mm, the wide grid line width is 0.1mm, and the length is 0.1mm. The cell after printing the electrode is dried and cured at a drying temperature of 150°C for 10 minutes and a curing temperature of 200°C for 30 minutes to complete the preparation of solar cells with open metal electrodes.

[0041] Implementation Case 2: A method for preparing a solar cell module, comprising the following steps:

[0042] S1: preparing a solar cell blue film, which is a part of the solar cell. Compared with a normal solar cell, the front and back of the blue film have no metal grid lines, and the other parts have the same structure as a conventional solar cell;

[0043] As an example, the solar cell blue film includes at least one of a crystalline silicon heterojunction cell (SHJ) with incident light on the N side, incident light on the P side, and incident light on both the N side and the P side;

[0044] S2: Forming metal electrodes on the back and front of the solar cell. The metal electrodes are composed of thin grid lines and wide grid lines. The metal electrodes of the solar cell are prepared by screen printing, electroplating, and inkjet printing. The metal used can be highly conductive materials such as Ag, Cu, Ni, Al, and their alloys;

[0045] The metal electrode reserves an opening of a certain width at the wide grid line position; the opening size is greater than or equal to the diameter or width of the metal welding strip used in the component, and the shapes of the openings include arc, rectangle, trapezoid, and polygon. The opening size is greater than or equal to the diameter or width of the metal welding strip used in the component, and the opening size is 0.01-5mm larger than the welding strip size.

[0046] As an example, metal front and back electrodes are prepared by screen printing on the front and back of the blue film, and arc-shaped openings are formed on the metal electrodes. The metal electrodes are divided into fine gate lines and wide gate lines. The arc-shaped openings are located in the middle of the wide gate lines. The width W of the wide gate lines is 1-10 times that of the fine gate lines. The length L of the wide gate lines is 0.01mm-5mm, and the opening size is 0.01mm-10mm.

[0047] S3: Lay the component encapsulation glass and encapsulation film, and position the metal welding strip on the encapsulation film. The metal welding strip is a copper strip coated with a low-temperature alloy. The cross-sectional shape of the metal welding strip includes arc, rectangle, trapezoid, polygon, and the diameter or width of the metal welding strip is 0.01mm-10mm. The metal welding strip is a copper strip coated with a low-temperature alloy. The low-temperature alloy includes tin-lead-bismuth, tin-bismuth-silver, tin-bismuth-indium, and the melting point of the alloy is 50-200℃;

[0048] A cell with an open metal electrode is placed on the metal welding strip, and the opening position of the metal electrode corresponds to the metal welding strip. As an example, the opening position of the metal electrode corresponds to the metal welding strip, and the welding strip is required to be placed at the opening position of the metal grid line;

[0049] A metal welding ribbon is placed on the surface of the battery cell, the welding ribbon is placed at the opening of the metal electrode of the battery cell, and then a packaging film and a backplane are placed; as an example, the material of the film includes but is not limited to at least one of ethylene vinyl acetate copolymer (EVA), ethylene-octene copolymer (POE) and thermoplastic polyolefin (TPO);

[0050] S4: placing the laid stack in a laminator, heating and pressurizing, and laminating to prepare components. The stack is laminated in the laminator, and the lamination temperature is greater than the melting point of the low-temperature solder strip, in order to melt the solder strip alloy, and the molten alloy fills the metal electrode opening, thereby increasing the contact area and improving reliability;

[0051] As an example, the temperature used in the laminator is 150° C.-165° C., and the lamination time is 10 min-40 min.

[0052] The fixed connection, fixed installation or fixed setting method includes existing common technologies, such as bolt fixing, welding, riveting, etc., all of which are for the purpose of fixing and do not affect the overall effect of the device.

[0053] Although the present invention is described herein with reference to a plurality of illustrative embodiments of the present invention, it should be understood that those skilled in the art may devise many other modifications and implementations that fall within the scope and spirit of the principles disclosed herein. More specifically, within the scope of the present disclosure and claims, a variety of variations and improvements may be made to the components and / or layout of the subject combination layout. In addition to variations and improvements made to the components and / or layout, other uses will also be apparent to those skilled in the art.

Claims

1. A method for preparing a solar cell, characterized in that: The following steps are involved: S1: preparing a blue film sheet for a solar cell, wherein the front and back sides of the blue film sheet have no metal grid lines; S2: forming metal electrodes on the back and front of the solar cell, the metal electrodes are composed of thin grid lines and wide grid lines, and the metal electrodes reserve openings of a certain width at the positions of the wide grid lines; S3: Lay the component encapsulation glass and encapsulation film, position and place the metal welding tape on the encapsulation film, place the battery cell with an open metal electrode on the metal welding tape, the opening position of the metal electrode corresponds to the metal welding tape, place the metal welding tape on the surface of the battery cell, the welding tape is placed at the opening position of the metal electrode of the battery cell, and then place the encapsulation film and the backplane; S4: placing the laid stack in a laminator, heating and pressurizing, and laminating to prepare an assembly.

2. The method for preparing a solar cell according to claim 1, characterized in that: The size of the opening is greater than or equal to the diameter or width of the metal welding strip used in the component, and the shape of the opening includes arc, rectangle, trapezoid, and polygon.

3. The method for preparing a solar cell according to claim 1, characterized in that: The metal welding strip is a copper strip coated with a low-temperature alloy coating, and the cross-sectional shape of the metal welding strip includes arc, rectangle, trapezoid, and polygon.

4. The method for preparing a solar cell according to claim 1, characterized in that: The metal welding strips used are highly conductive materials, including Ag, Cu, Ni, Al and their alloys.

5. The method for preparing a solar cell according to claim 1, characterized in that: The metal electrode is prepared by screen printing, electroplating or inkjet printing.

6. The method for preparing a solar cell according to claim 1, characterized in that: The width of the wide gate line is 1-10 times the width of the thin gate line.

7. The method for preparing a solar cell according to claim 1, characterized in that: The metal welding strip is a copper strip coated with a low-temperature alloy coating, wherein the low-temperature alloy includes tin-lead-bismuth, tin-bismuth-silver, tin-bismuth-indium, and the alloy melting point is 50-200°C.

8. The method for preparing a solar cell according to claim 1, characterized in that: The stack is laminated in a laminator at a temperature greater than the melting point of the low temperature solder tape.

9. A solar cell structure, comprising a blue film and a metal electrode, characterized in that: Prepared by the solar cell preparation method according to any one of claims 1 to 8; There are no metal electrode grid lines on the front and back of the blue film. A front transparent conductive film (101), an N-type doped hydrogenated amorphous silicon layer (102), a front intrinsic hydrogenated amorphous silicon layer (103), a crystalline silicon layer (104), a back intrinsic hydrogenated amorphous silicon layer (105), a P-type doped hydrogenated amorphous silicon layer (106), and a back transparent conductive film (107) are sequentially arranged between the front and back. The solar cell is provided with a metal electrode (108) with an opening on the front and a metal electrode (109) with an opening on the back. The metal electrodes include thin grid lines and wide grid lines. The metal electrodes are reserved with openings at the positions of the wide grid lines and are widened.

10. A solar cell module structure, characterized in that: Prepared by the solar cell preparation method according to any one of claims 1 to 8; The invention comprises a front side and a back side, wherein a front side metal electrode (108) with an opening, a front side transparent conductive film (101), an N-type doped hydrogenated amorphous silicon layer (102), a front side intrinsic hydrogenated amorphous silicon layer (103), a crystalline silicon layer (104), a back side intrinsic hydrogenated amorphous silicon layer (105), a P-type doped hydrogenated amorphous silicon layer (106), a back side transparent conductive film (107), and a back side metal electrode (109) with an opening are sequentially arranged between the front side and the back side, wherein metal electrodes are arranged on both the front side and the back side, wherein the metal electrodes comprise thin gate lines and wide gate lines, wherein the metal electrodes reserve openings at the positions of the wide gate lines and are widened, and metal welding strips are arranged in the reserved openings of the wide gate lines on the front side and the back side, and the metal welding strips connect the front side of a previous sub-battery with the back side of a next sub-battery.

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