Superparamagnetic electrically conductive fluid material, method for its preparation and magnetically connected laminated photovoltaic assembly

Abstract

The application provides a superparamagnetic conductive fluid material, a preparation method thereof and a magnetically connected laminated photovoltaic module; the preparation method comprises the following steps: a) dissolving FeCl2*4H2O and FeCl3*6H2O in water, then adding an NH3*H2O aqueous solution to carry out a coprecipitation reaction, separating and cleaning a solid product to obtain a Fe3O4 magnetic fluid; b) mixing the Fe3O4 magnetic fluid obtained in the step a) with a nano-silver conductive adhesive and a diluent, and carrying out ultrasonic dispersion to obtain the superparamagnetic conductive fluid material. Compared with the prior art, the application first synthesizes a superparamagnetic conductive fluid material, then coats the superparamagnetic conductive fluid material on a battery sheet overlapping connection setting area in a coating mode, the superparamagnetic conductive fluid material is rapidly magnetized under the action of a magnetic field, and loses magnetism rapidly after the external magnetic field disappears; when a single battery sheet has a defect, the damaged battery sheet can be easily disassembled and replaced, so that the waste of the battery sheet is reduced; meanwhile, the superparamagnetic conductive fluid material can also be used for the recycling and disassembly of the module after retirement.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module technology, and more specifically, to a superparamagnetic conductive fluid material, its preparation method, and a magnetically connected stacked photovoltaic module. Background Technology

[0002] With the continuous consumption of energy leading to rising energy prices, the development and utilization of new energy sources has become a major research topic in the energy field. Due to its numerous advantages, such as being pollution-free, not geographically limited, and inexhaustible, solar energy research has become one of the most popular directions in new energy development. Currently, using solar cells to generate electricity is a primary way for people to utilize solar energy. With the continuous development of photovoltaic technology, photovoltaic modules, which are semiconductor devices that convert solar energy into electrical energy, have been rapidly developed and their application areas are becoming increasingly broad.

[0003] Solar power generation is a technology that directly converts light energy into electrical energy by utilizing the photovoltaic effect at semiconductor interfaces. Photovoltaic modules, as the core unit of solar power generation, are generally composed of a cover glass, encapsulating film, solar cells, encapsulating film again, and a back panel. To reduce the levelized cost of electricity (LCOE) of solar power generation, tandem modules are a module structure that can significantly reduce incident light loss. Their basic principle is to cut the solar cells into several small pieces, which are directly interconnected by conductive adhesives. Matrix tandem modules have a photovoltaic module topology with two-dimensional current transport characteristics. Through the staggered arrangement of the solar cells, a mesh-like hybrid circuit connection method is achieved, connecting the cells in series vertically and in parallel horizontally. When the current transport of a cell string in the module encounters an obstruction (shading or cell damage), the current can continue to be transmitted through the parallel channel to the adjacent string, achieving detour around the obstruction point. This solves the problems of reduced power generation revenue caused by the decrease in photovoltaic module and system output power under shading conditions, as well as the safety hazards caused by hot spots.

[0004] Currently, crystalline silicon tandem photovoltaic modules utilize staggered cascading technology. This module design features a topological structure that enables two-dimensional current transport. It employs a staggered arrangement of slender strip cells (see tandem matrix module). Figure 1As shown, this is a photovoltaic module structure that relies on the grid lines of the solar cells to form parallel connection points, thereby achieving two-dimensional current transport. Adjacent two thin, elongated solar cells are connected by conductive adhesive applied via electroplating and extrusion through a stencil. There is an overlapping area between the long sides of the two adjacent solar cells, and the conductive adhesive is bonded to this overlapping area. The conductive adhesive has high viscosity, easily curing and clogging the nozzle. Furthermore, the extruded adhesive is difficult to control during the bonding of two solar cells, resulting in uneven spreading and potential overflow. This can cause short circuits in the solar module, affecting production yield and performance. During processing, solar cells may experience damage and cracking, and traditional conductive adhesives are difficult to swell and decompose after curing, sometimes requiring the scrapping of multiple solar cells or reducing the overall module performance. Summary of the Invention

[0005] In view of this, in order to overcome the shortcomings of the prior art, the present invention provides a superparamagnetic conductive fluid material, its preparation method, and a magnetically connected tandem photovoltaic module. First, a superparamagnetic conductive fluid material is prepared, and then it is coated onto the overlapping and connecting area of ​​the solar cells. A tandem photovoltaic module is then formed through a specific magnetic connection method. This superparamagnetic conductive fluid material is rapidly magnetized under the influence of a magnetic field and quickly loses its magnetism after the applied magnetic field disappears. When a defective individual solar cell is detected, the damaged cell can be easily disassembled and replaced, reducing cell waste. It can also be used for recycling and dismantling the module after its retirement. Furthermore, superparamagnetism is a controllable magnetic property; compared to ferromagnetic materials, two solar cells will not interact and shift, thus avoiding adsorption with metallic equipment during long-process transportation and preventing disruption of process flow.

[0006] This invention provides a method for preparing a superparamagnetic conductive fluid material, comprising the following steps:

[0007] a) Dissolve FeCl2·4H2O and FeCl3·6H2O in water, then add NH3·H2O aqueous solution to carry out coprecipitation reaction, separate and wash the solid product to obtain Fe3O4 magnetic fluid;

[0008] b) The Fe3O4 magnetic fluid obtained in step a) is mixed with nano-silver conductive adhesive and diluent, and then ultrasonically dispersed to obtain a superparamagnetic conductive fluid material.

[0009] Preferably, the molar ratio of FeCl2·4H2O, FeCl3·6H2O and NH3·H2O in step a) is 1:(1.5~2.5):(20~25).

[0010] Preferably, the process of dissolving FeCl2·4H2O and FeCl3·6H2O in water in step a) specifically involves:

[0011] First, add FeCl3·6H2O to water and stir to dissolve. After controlling the temperature at 70℃~85℃, add FeCl2·4H2O and mix well.

[0012] Preferably, the stirring speed for dissolving is 400 rpm to 600 rpm; the temperature is controlled by water bath heating.

[0013] Preferably, the co-precipitation reaction process described in step a) involving the addition of NH3·H2O aqueous solution is specifically as follows:

[0014] After dissolving FeCl2·4H2O and FeCl3·6H2O in water, the temperature is controlled at 80℃~90℃, and NH3·H2O aqueous solution is quickly poured in. The mixture is then stirred at a constant temperature for 1min~10min to generate a solid product.

[0015] Preferably, the concentration of the Fe3O4 magnetic fluid in step b) is 0.1 mol / L to 0.2 mol / L;

[0016] The volume ratio of the Fe3O4 magnetic fluid, nano-silver conductive adhesive, and diluent is (2.5-3.5):(1-2):(0.1-0.2).

[0017] Preferably, the mixing process in step b) specifically involves:

[0018] Under stirring conditions of 300 rpm to 500 rpm, nano-silver conductive adhesive and diluent were added sequentially to Fe3O4 magnetofluid, and stirred for 5 min to 10 min.

[0019] Preferably, the ultrasonic dispersion temperature in step b) is 40℃~60℃, the stirring speed is 200rpm~400rpm, and the time is 0.5h~2h.

[0020] The present invention also provides a superparamagnetic conductive fluid material, which is prepared by the preparation method described in the above technical solution.

[0021] The present invention also provides a magnetically connected stacked photovoltaic module, which is formed by a plurality of controllably magnetically connected crystalline silicon solar cells; one side of the front and the other side of the back of the controllably magnetically connected crystalline silicon solar cells are respectively provided with strip-shaped structures formed by coating and curing with a magnetic fluid; the magnetic fluid is the superparamagnetic conductive fluid material described in the above technical solution.

[0022] This invention provides a superparamagnetic conductive fluid material, its preparation method, and a magnetically connected tandem photovoltaic module. The preparation method includes the following steps: a) dissolving FeCl2·4H2O and FeCl3·6H2O in water, then adding an aqueous solution of NH3·H2O for co-precipitation reaction, separating and washing the solid product to obtain Fe3O4 magnetic fluid; b) mixing the Fe3O4 magnetic fluid obtained in step a) with nano-silver conductive adhesive and diluent, and ultrasonically dispersing to obtain the superparamagnetic conductive fluid material. Compared with the prior art, this invention first synthesizes a superparamagnetic conductive fluid material, and then coats it onto the overlapping connection area of ​​the solar cells. This superparamagnetic conductive fluid material is rapidly magnetized under the action of a magnetic field and quickly loses its magnetism after the external magnetic field disappears. When a defect is detected in a single solar cell, the damaged solar cell can be easily disassembled and replaced, reducing the waste of solar cells; it can also be used for the recycling and dismantling of the module after retirement.

[0023] Furthermore, the battery cells provided by this invention are easy to arrange closely, the connection parts are easy to fit together, the magnetic layer is evenly distributed and the area is controllable. At the same time, the connection between the battery cells can be eliminated, and it will not cause battery glue overflow and short circuit.

[0024] Furthermore, the magnetic materials used in this invention are inexpensive, have a simple preparation process, and have broad prospects for industrial application. Attached Figure Description

[0025] Figure 1 This refers to the overlapping structure of crystalline silicon matrix cascaded photovoltaic modules in existing technologies;

[0026] Figure 2 This is a schematic diagram of the battery cell processing in an application embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the magnetic connection in an application embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the tray arrangement table and magnetic positioning plate in an application embodiment of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention provides a method for preparing a superparamagnetic conductive fluid material, comprising the following steps:

[0031] a) Dissolve FeCl2·4H2O and FeCl3·6H2O in water, then add NH3·H2O aqueous solution to carry out co-precipitation reaction, separate and wash the solid product to obtain Fe3O4 magnetic fluid;

[0032] b) The Fe3O4 magnetic fluid obtained in step a) is mixed with nano-silver conductive adhesive and diluent, and then ultrasonically dispersed to obtain a superparamagnetic conductive fluid material.

[0033] This invention first dissolves FeCl2·4H2O and FeCl3·6H2O in water, then adds an aqueous solution of NH3·H2O to carry out a co-precipitation reaction. The solid product is then separated and washed to obtain Fe3O4 magnetic fluid. This invention does not have any special restrictions on the source of the FeCl2·4H2O, FeCl3·6H2O, and NH3·H2O aqueous solution; commercially available products well-known to those skilled in the art can be used. The water is preferably distilled water well-known to those skilled in the art.

[0034] In this invention, the molar ratio of FeCl2·4H2O, FeCl3·6H2O and NH3·H2O is preferably 1:(1.5~2.5):(20~25), more preferably 1:2:(22~23).

[0035] In this invention, the process of dissolving FeCl2·4H2O and FeCl3·6H2O in water is preferably as follows:

[0036] First, add FeCl3·6H2O to water and stir to dissolve. After controlling the temperature at 70℃~85℃, add FeCl2·4H2O and mix well.

[0037] More preferably:

[0038] First, add FeCl3·6H2O to water and stir to dissolve. After controlling the temperature at 75℃~80℃, add FeCl2·4H2O and mix well.

[0039] In this invention, the stirring speed for dissolving is preferably 400 rpm to 600 rpm, more preferably 500 rpm; the temperature control method is preferably water bath heating.

[0040] In this invention, the process of adding NH3·H2O aqueous solution for co-precipitation reaction is preferably as follows:

[0041] After dissolving FeCl2·4H2O and FeCl3·6H2O in water, the temperature is controlled at 80℃~90℃, and NH3·H2O aqueous solution is quickly poured in. Stirring is continued at a constant temperature for 5min~10min to generate a solid product.

[0042] More preferably:

[0043] After dissolving FeCl2·4H2O and FeCl3·6H2O in water, the temperature is controlled at 85℃, and then quickly poured into an aqueous solution of NH3·H2O. The mixture is then stirred at a constant temperature for 5 minutes to generate a solid product. In this invention, the volume of the NH3·H2O aqueous solution is preferably calculated based on the concentration of concentrated ammonia; however, this invention does not impose any special restrictions on this.

[0044] This invention uses the above-mentioned chemical co-precipitation method to prepare superparamagnetic Fe3O4 nanoparticles. The reaction equation is as follows:

[0045] 2Fe 3+ (aq)+Fe 2+ (aq) + 8OH - (aq)=Fe3O4(s)+4H2O (l).

[0046] The obtained Fe3O4 magnetic fluid was stored in alcohol; based on this, the subsequent concentration of Fe3O4 magnetic fluid is the concentration in alcohol.

[0047] After obtaining the Fe3O4 magnetic fluid, the present invention mixes the Fe3O4 magnetic fluid with nano-silver conductive adhesive and diluent, and then performs ultrasonic dispersion to obtain a superparamagnetic conductive fluid material. The present invention does not have any special restrictions on the source of the nano-silver conductive adhesive; commercially available products well known to those skilled in the art can be used. In a preferred embodiment of the present invention, the nano-silver content in the nano-silver conductive adhesive is preferably 50wt% to 70wt%.

[0048] In this invention, the diluent is preferably ethanol, the purpose of which is to slow down the drying and curing of the colloid; the source of the diluent is not particularly limited, and commercially available products known to those skilled in the art can be used.

[0049] In this invention, the concentration of the Fe3O4 magnetic fluid is preferably 0.1 mol / L to 0.2 mol / L, and more preferably 0.15 mol / L.

[0050] In this invention, the volume ratio of the Fe3O4 magnetic fluid, nano-silver conductive adhesive and diluent is preferably (2.5-3.5):(1-2):(0.1-0.2), more preferably 3:1.5:0.15.

[0051] In this invention, the mixing process is preferably specifically as follows:

[0052] Under stirring conditions of 300 rpm to 500 rpm, nano-silver conductive adhesive and diluent were added sequentially to Fe3O4 magnetofluid, and stirred for 5 min to 10 min.

[0053] More preferably:

[0054] Under stirring conditions of 400 rpm, nano-silver conductive adhesive and diluent were added sequentially to Fe3O4 magnetofluid, and stirred for 5 min to 10 min.

[0055] In a preferred embodiment of the present invention, an antifoaming agent is also added during the above mixing process; however, the present invention does not impose any particular limitation on this.

[0056] In this invention, the temperature of the ultrasonic dispersion is preferably 40℃~60℃, more preferably 50℃, and can be achieved by a water bath; the stirring speed of the ultrasonic dispersion is preferably 200rpm~400rpm, more preferably 300rpm; and the ultrasonic dispersion time is preferably 0.5h~2h, more preferably 1h.

[0057] The present invention also provides a superparamagnetic conductive fluid material, which is prepared by the preparation method described in the above technical solution.

[0058] The present invention also provides a magnetically connected stacked photovoltaic module, which is formed by a plurality of controllably magnetically connected crystalline silicon solar cells; one side of the front and the other side of the back of the controllably magnetically connected crystalline silicon solar cells are respectively provided with strip-shaped structures formed by coating and curing with a magnetic fluid; the magnetic fluid is the superparamagnetic conductive fluid material described in the above technical solution.

[0059] This invention is based on silicon-based matrix stacking technology, which combines superparamagnetic conductive fluid materials with specific positions of conventional crystalline silicon solar cells to form crystalline silicon solar cells with controllable magnetic connections.

[0060] In this invention, the controllable magnetically connected crystalline silicon solar cell has strip-shaped structures formed by coating and curing magnetic fluid on one side of the front and the other side of the back.

[0061] In this invention, the coating method is preferably template coating; the width of the strip structure is preferably 0.3mm to 0.4mm, more preferably 0.35mm, the distance from the edge of the strip structure is preferably 0.1mm to 0.3mm, more preferably 0.2mm, and the length of the strip structure is the overall length of the battery cell, which is not particularly limited in this invention.

[0062] In this invention, the curing method is heating and drying, the purpose of which is to achieve colloid curing; this invention has no special limitations on this, and heating and drying technical solutions well known to those skilled in the art can be used.

[0063] After forming the controllable magnetically connected crystalline silicon solar cells, the present invention magnetically connects several controllable magnetically connected crystalline silicon solar cells to form a magnetically connected stacked photovoltaic module; preferably, specifically:

[0064] The aforementioned controllable magnetically connected crystalline silicon solar cells are adsorbed onto the primary stacking stage by an electromagnetic chuck, and then demagnetized and desorbed. The primary stacking stage is equipped with pores and positioning electromagnetic points. During the stacking process, the cells are fixed by adsorption through the pores. After the stacking is completed, the electromagnetic field is turned on, and the magnetic strength of the electromagnetic points is sufficient to simultaneously adsorb two adjacent stacked solar cells and transfer them to the larger secondary stacking stage. The first layer of the secondary stacking stage is a strong magnetic positioning plate, followed by glass and EVA film. Busbars are welded onto the placed solar cells, and then the film and glass are covered. Finally, before being transported to the laminator feed inlet, the magnetic positioning plate is demagnetized and removed. After lamination, a magnetically connected stacked photovoltaic module is obtained.

[0065] The present invention employs the above-mentioned magnetic connection, which makes it easy to achieve a tight arrangement, the connection part is easy to fit, the magnetic layer is evenly distributed, and the area is controllable, thus obtaining a high-efficiency, high-density photovoltaic module; at the same time, the connection between the cells can be eliminated, and it will not cause short circuits due to glue overflow.

[0066] This invention provides a superparamagnetic conductive fluid material, its preparation method, and a magnetically connected tandem photovoltaic module. The preparation method includes the following steps: a) dissolving FeCl2·4H2O and FeCl3·6H2O in water, then adding an aqueous solution of NH3·H2O for co-precipitation reaction, separating and washing the solid product to obtain Fe3O4 magnetic fluid; b) mixing the Fe3O4 magnetic fluid obtained in step a) with nano-silver conductive adhesive and diluent, and ultrasonically dispersing to obtain the superparamagnetic conductive fluid material. Compared with the prior art, this invention first synthesizes a superparamagnetic conductive fluid material, and then coats it onto the overlapping connection area of ​​the solar cells. This superparamagnetic conductive fluid material is rapidly magnetized under the action of a magnetic field and quickly loses its magnetism after the external magnetic field disappears. When a defect is detected in a single solar cell, the damaged solar cell can be easily disassembled and replaced, reducing the waste of solar cells; it can also be used for the recycling and dismantling of the module after retirement.

[0067] Furthermore, the battery cells provided by this invention are easy to arrange closely, the connection parts are easy to fit together, the magnetic layer is evenly distributed and the area is controllable. At the same time, the connection between the battery cells can be eliminated, and it will not cause battery glue overflow and short circuit.

[0068] Furthermore, the magnetic materials used in this invention are inexpensive, have a simple preparation process, and have broad prospects for industrial application.

[0069] To further illustrate the present invention, the following embodiments provide a detailed description. All raw materials used in the following embodiments of the present invention are commercially available; the nano-silver conductive adhesive used is conductive adhesive DA-1500A.

[0070] Example 1

[0071] (1) Weigh 0.043 mol (8.55 g) of ferrous chloride tetrahydrate (FeCl2·4H2O) and 0.086 mol (23.25 g) of ferric chloride hexahydrate (FeCl3·6H2O) to prepare an iron salt solution. First, add ferric chloride hexahydrate to a beaker containing 250 ml of distilled water and stir at 500 rpm until dissolved. In a water bath, when the temperature is raised to 75-80℃, add ferrous chloride tetrahydrate and mix evenly. At 85℃, quickly pour in an aqueous solution containing 0.956 mol NH3·H2O and continue to stir at a constant temperature for 5 min. Wash repeatedly with deionized water and magnetic separation to obtain a bright black Fe3O4 magnetic fluid, which is stored in alcohol.

[0072] (2) Measure Fe3O4 magnetic fluid (concentration 0.15mol / L) and nano-silver conductive adhesive at a volume ratio of 3:1.5. Slowly add the nano-silver conductive adhesive to the Fe3O4 magnetic fluid at 400rpm, then add ethanol at a volume ratio of 10% to the nano-silver conductive adhesive as a diluent to slow down the drying and curing of the adhesive. Add 0.1% by mass of defoamer. ADP561), humidified to 85%, stirred for 5-10 minutes, then dispersed for 1 hour in a 50°C water bath while being ultrasonically stirred at 300 rpm, to obtain a superparamagnetic conductive fluid material.

[0073] Application Examples

[0074] The superparamagnetic conductive fluid material obtained by the preparation method provided in Example 1 was coated onto the connection site of the crystalline silicon solar cell using a template coating method. (See below) Figure 2 As shown, Figure 2 This is a schematic diagram of the battery cell processing in an application embodiment of the present invention; wherein, a strip-shaped structure with a width of 0.35mm and a distance of 0.2mm from the right edge is coated on one side (right side) of the front of the battery cell, which is the front magnetic grid, and a strip-shaped structure with a width of 0.35mm and a distance of 0.2mm from the left edge is also coated on the other side (left side) of the back of the battery cell, which is the back magnetic grid; then, after heating, drying and curing, a crystalline silicon battery cell with controllable magnetic connection is obtained.

[0075] Then, several controllably magnetically connected crystalline silicon solar cells are magnetically connected, see [link to documentation]. Figure 3 As shown, Figure 3 This is a schematic diagram of the magnetic connection in an application embodiment of the present invention; the electromagnetic chuck used in the figure is an energized electromagnet, which serves to attract a single cell or two adjacent overlapping battery cells at the same time; the superparamagnetic conductive fluid material has conductive properties and serves to collect electrons and connect the metal electrodes of the battery cells in series.

[0076] The aforementioned controllable magnetically connected crystalline silicon solar cells are attracted to the primary stacking stage by an electromagnetic chuck, and then demagnetized and de-adsorbed. The primary stacking stage is equipped with pores and positioning electromagnetic points. During the stacking process, the cells are attracted and fixed by the pores. After stacking, the electromagnetic field is activated, and the electromagnetic points have sufficient magnetic strength to simultaneously attract two adjacent stacked solar cells and transfer them to a larger secondary stacking stage. The first layer of the secondary stacking stage is a strongly magnetic positioning plate (e.g., ...). Figure 4 As shown, Figure 4 (A schematic diagram of the cell stacking platform and magnetic positioning plate) Then, glass and EVA film are applied in sequence; busbars are welded onto the placed cells, then covered with film and glass, and finally transported to the laminator feed inlet. The magnetic positioning plate is demagnetized and removed, and after lamination, magnetically connected stacked photovoltaic modules are obtained.

[0077] Magnetic-connected laminated photovoltaic modules can be uniformly coated with a thin layer of adhesive on the edges of the cells, avoiding short circuits and shading caused by excess adhesive. It also reduces the proportion of non-conductive materials such as organic matter, improving conductivity and effectively increasing module efficiency. The magnetic fluid itself has a certain degree of adhesion, and adding conductive adhesive improves the relative stability of the cells in the absence of a magnetic field, reducing positional deviations after cell arrangement. Furthermore, this material allows for simple and effective disassembly. In conventional production, if even one cell is damaged, the entire module is scrapped; however, magnetic connections allow for removal and replacement, significantly reducing cell waste and loss on the production line.

[0078] Table 1 shows a comparison of photovoltaic modules using the same batch of cells.

[0079] Table 1 Comparative data of photovoltaic modules using the same batch of solar cells.

[0080] Connect using pure conductive adhesive 521.4 528.7 519.8 Using magnetic connection 529.7 536.5 540.2

[0081] Calculations show that the average yield is 95%, the cost of a single 540MW module is 1080 yuan, and the 10MW production line saves 1 million yuan in costs.

[0082] This invention provides a superparamagnetic conductive fluid material, its preparation method, and a magnetically connected tandem photovoltaic module. First, a superparamagnetic conductive fluid material (magnetic fluid) is synthesized. Then, the magnetic fluid is coated onto the overlapping and connecting areas of the solar cells. This superparamagnetic conductive fluid material is rapidly magnetized under a magnetic field and quickly loses its magnetism after the applied magnetic field disappears. When a defective individual solar cell is detected, the damaged cell can be easily disassembled and replaced, reducing cell waste. It can also be used for the recycling and dismantling of the module after its retirement. Superparamagnetism is a controllable magnetic property. Compared to ferromagnetic materials, two solar cells do not interact and shift, and it avoids adsorption with metal equipment during long-haul transportation, thus preventing disruption to the process flow. Furthermore, the solar cells used in this invention are easily arranged in a close configuration, the connecting parts are easily bonded, the magnetic layer is uniformly distributed, and the area is controllable. The connections between solar cells are also eliminateable, preventing short circuits caused by excess adhesive. In addition, the magnetic material used in this invention is inexpensive, the preparation process is simple, and it has broad prospects for industrial application.

[0083] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A magnetically connected tandem photovoltaic module, characterized in that, It is formed by magnetically connecting several controllably magnetically linked crystalline silicon solar cells; specifically: The aforementioned controllable magnetically connected crystalline silicon solar cells are adsorbed onto the primary stacking stage by an electromagnetic chuck, and then demagnetized and desorbed. The primary stacking stage is equipped with pores and positioning electromagnetic points. During the stacking process, the cells are adsorbed and fixed by the pores. After the stacking is completed, the electromagnetic field is turned on. The magnetic strength of the electromagnetic points is sufficient to simultaneously adsorb two adjacent stacked solar cells and transfer them to the larger secondary stacking stage. The first layer of the secondary stacking stage is a strong magnetic positioning plate, followed by glass and EVA film in sequence. Busbars are welded onto the placed solar cells, then covered with adhesive film and glass. Finally, before being transported to the feed inlet of the laminator, the magnetic positioning plate is demagnetized and removed. After lamination, a magnetically connected stacked photovoltaic module is obtained. The controllable magnetically connected crystalline silicon solar cell has a strip-shaped structure formed by coating and curing a magnetic fluid on one side of its front side, which is the front magnetic grid, and a strip-shaped structure formed by coating and curing a magnetic fluid on the other side of its back side, which is the back magnetic grid; the width of the strip-shaped structure is 0.3mm~0.4mm. The magnetic fluid is a superparamagnetic conductive fluid material; the preparation method of the superparamagnetic conductive fluid material includes the following steps: a) Dissolve FeCl2·4H2O and FeCl3·6H2O in water, then add NH3·H2O aqueous solution to carry out coprecipitation reaction, separate and wash the solid product to obtain Fe3O4 magnetic fluid; b) The Fe3O4 magnetic fluid obtained in step a) is mixed with nano-silver conductive adhesive and diluent, and then ultrasonically dispersed to obtain a superparamagnetic conductive fluid material; the concentration of the Fe3O4 magnetic fluid is 0.1 mol / L to 0.2 mol / L; The volume ratio of the Fe3O4 magnetic fluid, nano-silver conductive adhesive, and diluent is (2.5~3.5):(1~2):(0.1~0.2).

2. The shingled photovoltaic module according to claim 1, characterized in that, The molar ratio of FeCl2·4H2O, FeCl3·6H2O and NH3·H2O in step a) is 1:(1.5~2.5):(20~25).

3. The shingled photovoltaic module according to claim 1, characterized in that, The process of dissolving FeCl2·4H2O and FeCl3·6H2O in water as described in step a) is as follows: First, add FeCl3·6H2O to water and stir to dissolve. After controlling the temperature at 70℃~85℃, add FeCl2·4H2O and mix well.

4. The shingled photovoltaic module according to claim 3, characterized in that, The stirring speed for dissolving is 400 rpm to 600 rpm; the temperature is controlled by water bath heating.

5. The shingled photovoltaic module according to claim 1, characterized in that, The process of adding NH3·H2O aqueous solution to carry out the coprecipitation reaction in step a) is specifically as follows: After dissolving FeCl2·4H2O and FeCl3·6H2O in water, the temperature is controlled at 80℃~90℃, and NH3·H2O aqueous solution is quickly poured in. The mixture is then stirred at a constant temperature for 1min~10min to generate a solid product.

6. The shingled photovoltaic module according to claim 1, characterized in that, The mixing process described in step b) is specifically as follows: Under stirring conditions of 300 rpm to 500 rpm, nano-silver conductive adhesive and diluent were added sequentially to Fe3O4 magnetofluid, and stirred for 5 min to 10 min.

7. The shingled photovoltaic module according to claim 1, characterized in that, The ultrasonic dispersion in step b) is performed at a temperature of 40℃~60℃, a stirring speed of 200rpm~400rpm, and a time of 0.5h~2h.

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