Foldable photovoltaic cells and portable solar devices

Abstract

The utility model discloses a foldable photovoltaic cell and a portable solar device, comprising a solar cell without a main grid line, a copper alloy wire and an encapsulation film layer, the front and back of the solar cell have auxiliary grid lines, the copper alloy wire comprises a front section, a connection section and a back section, the front section is arranged on the front of the solar cell and cross-connected with the auxiliary grid line on the front, the back section is arranged on the back of another solar cell and cross-connected with the auxiliary grid line on the back, an insulating layer is provided on the surface of the connection section and is located between two adjacent cells, the encapsulation film layer is encapsulated on the front of the solar cell arranged with the copper alloy wire, and a plurality of solar cells are connected in series through the copper alloy wire. Compared with the design of the main grid line, the foldable photovoltaic cell of the utility model can reduce the shading area, improve the current collection efficiency, has good foldability, and can be applied to a wider range of scenes, and can be used for portable solar devices that need to be moved.

Description

Technical Field

[0001] The utility model belongs to the technical field of photovoltaic solar cells, and in particular relates to a foldable photovoltaic cell and a portable solar device. Background Art

[0002] Photovoltaic cells are usually packaged into large-sized rigid photovoltaic panels with glass panels and backplanes. They cannot be bent and their application scenarios are very limited. They are not suitable for small solar devices with small light-seeing areas, uneven light-seeing surfaces, and lightweight and movable. In addition, the utilization rate of light energy by conventional photovoltaic cells is low. At the same time, due to the small light absorption area of ​​small solar devices, the power supply is not ideal. Due to the bandgap structure, traditional silicon-based photovoltaic cells have insufficient absorption and conversion capacity for photon energy in the ultraviolet light band, which is an important factor limiting silicon-based cells. At the same time, the grid lines on the front of the cell will block part of the incident light, reducing the light-receiving area of ​​the cell and reducing the photoelectric conversion efficiency of the cell. In order to improve the absorption capacity of silicon-based cells for sunlight in the ultraviolet band, the conventional method is to use perovskite cells and change the cell structure to form a perovskite-silicon-based stacked structure. By taking advantage of the wide bandgap of perovskites, high-energy photons in the ultraviolet light band can be effectively absorbed to improve the utilization rate of solar energy. However, the perovskite battery itself has problems such as poor material stability, fast power attenuation, low battery life, and difficulty in large-size manufacturing, which reduces the service life of the laminated battery assembly; 0BB (no main grid) or XBC (no grid line) technology is used to solve the efficiency loss problem caused by the front grid line shading. This type of technology reduces or prevents the front shading loss by designing the front of the battery without a main grid or grid line. In particular, 0BB technology has become one of the confirmed qualitative directions in the upgrade of N-type technology. As a universal cost reduction process, 0BB can reduce the silver paste consumption and reduce the shading area to improve the battery efficiency while ensuring the current output through the design of no main grid on the front of the battery. However, the current collection efficiency of the no main grid design is low. Although it reduces the light blocking to a certain extent, the technology fails to improve the utilization rate of light, and the battery still cannot effectively utilize the light outside the visible light band. Sunlight can be divided into ultraviolet band, visible light band, and infrared band according to wavelength, and the energy decreases in turn. Conventional crystalline silicon cells mainly absorb light in the visible light band and cannot effectively utilize light in the ultraviolet band, resulting in insufficient utilization of sunlight by crystalline silicon cells and limited efficiency improvements. Utility Model Content

[0003] The technical problem to be solved by the utility model is to overcome the deficiencies of the prior art and provide a foldable photovoltaic cell and a portable solar device with high current collection efficiency and relatively small shading area.

[0004] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0005] A foldable photovoltaic cell comprises a solar cell without a main grid line, a copper alloy wire and a packaging film layer, wherein the front and back sides of the solar cell are provided with secondary grid lines, the copper alloy wire comprises a front section, a connecting section and a back section, the front section is arranged on the front side of the solar cell and cross-connected with the secondary grid line on the front side, the back section is arranged on the back side of another solar cell and cross-connected with the secondary grid line on the back side, an insulating layer is provided on the surface of the connecting section and is located between two adjacent solar cells, the packaging film layer is packaged on the front side of the solar cell provided with the copper alloy wire, and a plurality of the solar cells are connected in series through the copper alloy wire.

[0006] In the above-mentioned foldable photovoltaic cell, preferably, the encapsulation film layer is a film layer containing a down-conversion material.

[0007] In the above-mentioned foldable photovoltaic cell, preferably, the surface of the copper alloy wire that is not in contact with the solar cell is coated with a down-conversion material layer.

[0008] In the above-mentioned foldable photovoltaic cell, preferably, the down-conversion material in the adhesive film layer containing the down-conversion material is an inorganic dysprosium yttrium phosphate-based nanocrystalline fluorescent powder material; the down-conversion material in the down-conversion material layer is an inorganic dysprosium yttrium phosphate-based nanocrystalline fluorescent powder material.

[0009] In the above-mentioned foldable photovoltaic cell, preferably, the copper alloy wire is a copper-tin alloy wire.

[0010] In the above-mentioned foldable photovoltaic cell, preferably, the copper alloy wire is a copper indium tin alloy wire.

[0011] In the above-mentioned foldable photovoltaic cell, preferably, the encapsulation film layer is an EVA film.

[0012] In the above-mentioned foldable photovoltaic cell, preferably, there are multiple copper alloy wires, and the multiple copper alloy wires are parallel to each other and arranged perpendicular to the secondary grid lines.

[0013] As a general technical concept, the utility model also provides a portable solar device, including a foldable photovoltaic cell, a voltage stabilizing unit, a power storage unit and a charging unit electrically connected in sequence, wherein the foldable photovoltaic cell is the foldable photovoltaic cell mentioned above.

[0014] The above-mentioned portable solar energy device is a solar backpack, a solar jacket, a solar tent or a solar outdoor work vehicle, and the foldable photovoltaic cell is arranged on the light-exposure surface of each of the portable solar energy devices.

[0015] Compared with the prior art, the advantages of the utility model are:

[0016] (1) The foldable photovoltaic cell of the utility model arranges copper alloy wires on the surface of the battery without main grid lines on the front side, cross-connects the front section of the copper alloy wires with the auxiliary grid lines on the front side of the solar cell, and cross-connects the back section of the copper alloy wires with the auxiliary grid lines on the back side of another solar cell, thereby realizing the series connection of two adjacent solar cells. Among them, the cross-connection of the copper alloy wires with good conductive properties and the auxiliary grid lines can quickly collect the current on the solar cell, overcoming the problem of low current collection efficiency of the design without main grid lines. At the same time, through practical research, it is found that the use of copper alloy wires can reduce the shading area by about 20% compared with the main grid lines under the condition of having the same current collection efficiency. The alloy wires and the auxiliary grid lines are connected by spot welding + lamination, which can also improve the contact. In addition, copper alloy wire has high mechanical strength and certain toughness. Photovoltaic cells composed of multiple solar cells connected in series with copper alloy wire are foldable and easy to fold and store. They can be used on uneven and irregular light-exposed surfaces, such as solar backpacks, solar jackets, solar tents or solar outdoor work vehicles, etc., which have uneven light-exposed surfaces and require the flexibility and foldability of photovoltaic cells. The applicable scenarios are wider.

[0017] (2) The foldable photovoltaic cell of the utility model uses a film layer containing down-conversion materials as an encapsulation film layer, which can convert high-energy photons in the ultraviolet band of sunlight into low-energy photons, so that the light in the ultraviolet band of sunlight can be effectively utilized by silicon-based batteries. At the same time, copper alloy wires are used to improve the efficiency of current collection on the surface of the battery. Thus, on the basis of increasing the light receiving area of ​​0BB batteries, the utilization rate of short-wave sunlight and the collection capacity of current on the surface of the battery are further improved. The film layer containing down-conversion materials, that is, the solar cell encapsulation film layer containing down-conversion materials, has structural stability, water resistance, corrosion resistance and flexibility, and also has the advantages of improving the utilization rate of light energy. It is more suitable for lightweight components, mobile photovoltaic products and other products that pursue high power density and are easy to carry.

[0018] (3) The foldable photovoltaic cell of the utility model is coated with a down-conversion material layer on the surface of the copper alloy wire that is not in contact with the solar cell, thereby changing the light shielding of the copper alloy wire to absorbing ultraviolet light and converting it into visible light that can be used by the solar cell, further improving the overall utilization rate of light energy by the foldable photovoltaic cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the layer structure of a foldable photovoltaic cell according to a specific embodiment of the utility model.

[0020] Figure 2 It is a schematic diagram of the connection between adjacent solar cells in a foldable photovoltaic cell according to a specific embodiment of the utility model.

[0021] Figure 3The cross-sectional structure and principle diagram of a foldable photovoltaic cell according to a specific embodiment of the utility model.

[0022] The reference numerals in the figure indicate: 1, solar cell; 11, secondary grid line; 2, copper alloy line; 3, packaging film layer; 31, film containing down-conversion material; 32, down-conversion material layer. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0024] Figures 1 to 3 A specific embodiment of the foldable photovoltaic cell of the utility model is shown, including a solar cell 1 without a main grid line, a copper alloy wire 2 and a packaging film layer 3, the front and back sides of the solar cell 1 are provided with auxiliary grid lines 11, the copper alloy wire 2 includes a front section, a connecting section and a back section, the front section is arranged on the front side of the solar cell 1 and cross-connected with the auxiliary grid line 11 on the front side, the back section is arranged on the back side of another solar cell 1 and cross-connected with the auxiliary grid line 11 on the back side, an insulating layer is provided on the surface of the connecting section and is located between two adjacent solar cells 1, the packaging film layer 3 is encapsulated on the front side of the solar cell 1 arranged with the copper alloy wire 2, and multiple solar cells 1 are connected in series through the copper alloy wire 2.

[0025] The foldable photovoltaic cell of this embodiment arranges copper alloy wires 2 on the surface of the cell without main grid lines on the front side, cross-connects the front section of the copper alloy wires 2 with the auxiliary grid lines 11 on the front side of the solar cell 1, and cross-connects the back section of the copper alloy wires 2 with the auxiliary grid lines 11 on the back side of another solar cell 1, thereby realizing the series connection of two adjacent solar cells 1. Among them, the cross-connection of the copper alloy wires 2 with good conductive properties and the auxiliary grid lines 11 can quickly collect the current on the solar cell 1, overcoming the problem of low current collection efficiency of the design without main grid lines. At the same time, through practical research, it is found that the use of copper alloy wires 2 can reduce the shading area by about 20% compared with the main grid lines under the condition of having the same current collection efficiency. The alloy wires and the auxiliary grid lines are connected by spot welding + lamination, which can improve the contact. In addition, the copper alloy wire 2 has high mechanical strength and certain toughness. The photovoltaic cell composed of multiple cells connected in series with the copper alloy wire 2 is foldable and easy to fold and store. It can be used on uneven and irregular light-exposed surfaces, such as solar backpacks, solar jackets, solar tents or solar outdoor work vehicles, etc., which have uneven light-exposed surfaces and require the flexibility and foldability of photovoltaic cells. The applicable scenarios are wider.

[0026] Among them, the encapsulation film layer 3 can adopt a conventional solar cell encapsulation film layer, such as the EVA (ethylene-vinyl acetate copolymer) film or POE (polyolefin elastomer) film that is more commonly used on the market. Conventional hot pressing packaging is adopted during packaging. After the encapsulation film layer 3 is softened by heat, the copper alloy wire 2 except the connection with the auxiliary grid line 11 is embedded in the encapsulation film layer 3 under the action of pressure. After cooling and solidification, the packaging is completed.

[0027] like Figure 3 As shown, the encapsulation film layer 3 of the present embodiment is a film layer 31 containing a down-conversion material, that is, a solar cell encapsulation film containing a down-conversion material. The down-conversion material is a material that can convert high-energy photons into low-energy photons. This characteristic is utilized in the crystalline silicon cell encapsulation film layer, which can absorb high-energy photons in the ultraviolet band of sunlight and release multiple photons in the visible light band that can be absorbed by the crystalline silicon cell, thereby effectively improving the utilization rate of sunlight by the crystalline silicon cell. Therefore, the film layer 31 containing the down-conversion material of the present embodiment can convert high-energy photons in the ultraviolet band of sunlight into low-energy photons, so that the light in the ultraviolet band of sunlight can be effectively utilized by the silicon-based cell, and the copper alloy wire 2 is used to improve the surface current collection efficiency of the cell, thereby achieving the further improvement of the utilization rate of short-wavelength sunlight and the surface current collection capacity of the silicon-based cell on the basis of increasing the light receiving area of ​​the 0BB cell. This film not only has the advantages of structural stability, water resistance, corrosion resistance and flexibility of conventional solar cell encapsulation film layers, but also has the advantage of improving the utilization rate of light energy. It is more suitable for lightweight components, mobile photovoltaic products and other products that pursue high power density and are easy to carry.

[0028] Among them, the film layer 31 containing the down-conversion material is an existing material, which can be purchased or prepared by referring to the existing technical scheme. The present embodiment is preferably prepared according to the following existing scheme: the down-conversion powder particles are placed in high-temperature molten ethylene-vinyl acetate copolymer, stirred by a magnetic stirrer to make it evenly distributed, and then a cross-linking agent, a coupling agent, and an anti-aging agent are added and mixed and cooled to form a film material, copper alloy wires 2 are laid on the front and back of the 0BB battery and connected with the gate wires 11 by spot welding, and the film material and the battery are laminated. Among them, the mass percentage of the amount of each component of the film is 90% to 99% of ethylene-vinyl acetate copolymer, 0.3% to 5% of the cross-linking agent, 0.3% to 5% of the coupling agent, 0.3% to 5% of the anti-aging agent, and 0.1% to 1% of the down-conversion powder particles (the raw materials are all conventional raw materials and can be purchased). The adhesive film uses ethylene-vinyl acetate copolymer with good water resistance, and is more stable when combined with inorganic down-conversion materials. The down-conversion materials in the adhesive film can effectively convert high-energy photons into low-energy photons for use by the solar cell 1. At the same time, the adhesive film contains copper alloy wires 2 inside, and the structure is stable. The solar cells are connected by the copper alloy wires 2, which is convenient for folding and use, and is suitable for portable devices and outdoor use scenarios.

[0029] In this embodiment, the surface of the copper alloy wire 2 that is not in contact with the solar cell 1 is coated with a down-conversion material layer 32, which can be a down-conversion material powder or a film layer. Therefore, the down-conversion material film 32 on the copper alloy wire 2 can absorb ultraviolet light and convert it into visible light that can be used by the solar cell 1. The light obliquely incident on the copper alloy wire 2 can be reflected into the cell surface, further improving the overall utilization rate of light energy by the foldable photovoltaic cell.

[0030] Further optimized, the down-conversion materials in the encapsulation film layer 3 and on the surface of the copper alloy wire 2 of this embodiment are both inorganic dysprosium yttrium phosphate nanocrystalline phosphor materials. The inorganic dysprosium yttrium phosphate nanocrystalline phosphor materials are existing materials and can be purchased or prepared by referring to the existing technical solutions. This embodiment is preferably prepared by the existing solid phase reaction method. The raw materials used for the synthetic sample include Y2O3 (99.9999%), P2O5 (99.9%), Pr2O3 (99.9%) and Yb2O3 (99.99%), and the ratio requirement is Y 3+ 20%~49%, P 5+ 20%~49%, Pr 3+ 1%~10%, Yb 3+ 1% to 30%. Raw materials are weighed according to the stoichiometric ratio, mixed with anhydrous ethanol as a medium and ball-milled for 18 hours to form a slurry for spraying to obtain down-conversion powder particles with a particle size of less than 10 μm (the raw materials are all conventional raw materials and can be purchased). Of course, in other embodiments, the down-conversion material can also use other down-conversion powders.

[0031] In this embodiment, the copper alloy wire 2 is a copper-tin alloy wire. The copper alloy wire 2 is laid on a substrate and sprayed with a down-conversion material powder to cover the down-conversion material layer 32, while leaving the bottom copper alloy wire exposed. Figure 2 As shown, the alloy wire is laid on both sides of the solar cell 1, and the film layer 31 containing the down-conversion material is laid on the front side for lamination. During the lamination process of the front side of the 0BB battery, the alloy wire can complete the metallization of the spot welding position with the battery auxiliary grid line, so that the two are in full contact, which is conducive to ensuring good conductivity. Among them, the copper-tin alloy wire is an existing material and can be purchased. It is preferred to use the 0.06mm Cu (Sn) alloy wire produced by Shanghai Liangjiu Co., Ltd., or use Cu (In, Sn) alloy wire to better achieve metallization with the 0BB battery.

[0032] In this embodiment, there are multiple copper alloy wires 2 , and the multiple copper alloy wires 2 are parallel to each other and arranged perpendicular to the secondary gate line 11 .

[0033] In summary, this embodiment is based on 0BB technology, and a conductive copper alloy wire 2 is added to the battery packaging film layer 3 to form a copper alloy wire composite film, which can effectively collect the current on the battery surface and reduce the shading area. Down-conversion materials are doped in the copper alloy wire composite film to form a film with down-conversion function. Under the premise of meeting the current collection capacity, the film layer structure can convert the absorbed ultraviolet light into visible light for battery absorption and utilization, thereby improving the battery efficiency. At the same time, the foldable photovoltaic cell composed of multiple solar cells 1 connected in series using copper alloy wires 2 is lightweight and foldable, and has good portability.

[0034] This embodiment also provides a portable solar device, comprising a foldable photovoltaic cell, a voltage stabilizing unit, a power storage unit and a charging unit electrically connected in sequence, wherein the foldable photovoltaic cell is the foldable photovoltaic cell described above in this embodiment. The portable solar device made of the foldable photovoltaic cell described above in this embodiment also has the same advantages as the foldable photovoltaic cell described above.

[0035] Further preferably, the portable solar device of the present embodiment is a solar backpack, a solar jacket, a solar tent or a solar outdoor work vehicle, and the foldable photovoltaic cell is arranged on the light-exposed surface of each portable solar device. The portable solar device of the present embodiment can meet the power demand of small electronic products such as mobile phones, tablets, MP4s, digital cameras, flashlights, electric mosquito coils, etc., and is particularly suitable for emergency use when there is no power supply in the wild, reducing the dependence of outdoor travel or work on fixed power supplies, and providing more convenience for outdoor travelers and outdoor workers.

[0036] Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with the art can use the above disclosed technical content to make many possible changes and modifications to the technical solution of the present invention without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A foldable photovoltaic cell, characterized in that: The invention comprises a solar cell (1) without a main grid line, a copper alloy wire (2) and a packaging film layer (3), wherein the front and back sides of the solar cell (1) are provided with auxiliary grid lines (11), the copper alloy wire (2) comprises a front section, a connecting section and a back section, the front section is arranged on the front side of the solar cell (1) and cross-connected with the auxiliary grid line (11) on the front side, the back section is arranged on the back side of another solar cell (1) and cross-connected with the auxiliary grid line (11) on the back side, an insulating layer is provided on the surface of the connecting section and is located between two adjacent solar cells (1), the packaging film layer (3) is packaged on the front side of the solar cell (1) provided with the copper alloy wire (2), and a plurality of solar cells (1) are connected in series via the copper alloy wire (2).

2. The foldable photovoltaic cell according to claim 1, characterized in that: The encapsulation film layer (3) is a film layer (31) containing a down-conversion material.

3. The foldable photovoltaic cell according to claim 2, characterized in that: The surface of the copper alloy wire (2) not in contact with the solar cell sheet (1) is coated with a down-conversion material layer (32).

4. The foldable photovoltaic cell according to claim 3, characterized in that: The down-conversion material in the adhesive film layer (31) containing the down-conversion material is an inorganic dysprosium yttrium phosphate type nanocrystalline fluorescent powder material; the down-conversion material in the down-conversion material layer (32) is an inorganic dysprosium yttrium phosphate type nanocrystalline fluorescent powder material.

5. The foldable photovoltaic cell according to claim 1, characterized in that: The copper alloy wire (2) is a copper-tin alloy wire.

6. The foldable photovoltaic cell according to claim 1, characterized in that: The copper alloy wire (2) is a copper indium tin alloy wire.

7. The foldable photovoltaic cell according to claim 1, characterized in that: The packaging film layer (3) is an EVA film.

8. The foldable photovoltaic cell according to any one of claims 1 to 7, characterized in that: There are multiple copper alloy wires (2), and the multiple copper alloy wires (2) are parallel to each other and arranged perpendicularly to the secondary grid lines (11).

9. A portable solar device, characterized in that: It comprises a foldable photovoltaic cell, a voltage stabilizing unit, a power storage unit and a charging unit which are electrically connected in sequence, and the foldable photovoltaic cell is the foldable photovoltaic cell according to any one of claims 1 to 8.

10. The portable solar device according to claim 9, characterized in that: The portable solar device is a solar backpack, a solar jacket, a solar tent or a solar outdoor work vehicle, and the foldable photovoltaic cell is arranged on the light-exposure surface of each portable solar device.

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