Self-cleaning photovoltaic cable and preparation method therefor

Abstract

Disclosed in the present invention is a preparation method for a self-cleaning photovoltaic cable. The cable comprises a conductor, a halogen-free cross-linked insulating layer and a halogen-free cross-linked sheath layer. The preparation method comprises the following steps: S1, sequentially coating a cable conductor with a halogen-free cross-linked insulating layer and a halogen-free cross-linked sheath layer, and performing irradiation; and S2, performing laser etching on the surface of the halogen-free cross-linked sheath layer to obtain a concentric pattern, wherein the concentric pattern comprises, in sequence from the center outward, a non-etching region and at least two etching regions, and the pulse energy of the etching regions gradually increases from the center outward. In the present invention, laser etching is performed on the surface of a cross-linked sheath layer to obtain a three-dimensional structure with the roughness gradually increasing from the inside outward, such that the surface of a cable has a super-hydrophobic property; droplets on the surface of the cable move in a rolling way to the central region to form drops, such that the surface of the cable has a super-hydrophobic property; and droplets rest on the surface of the cable and move in a rolling way to take away organic and inorganic solid particles from the surface of the cable, thereby realizing a self-cleaning effect.

Description

Self-cleaning photovoltaic cable and preparation method thereof Technical Field

[0001] The present invention relates to a cable, in particular to a self-cleaning photovoltaic cable and a preparation method thereof. Background Art

[0002] With the continuous development of new energy technologies, the installed capacity of photovoltaic power generation has also continued to increase. However, after long-term operation of photovoltaic power stations, a lot of dust or impurities are generated on the surfaces of various parts, which will significantly affect the power generation efficiency. In order to maintain the basic power generation level and efficiency of photovoltaic power stations and increase the total power generation, a scientific and reasonable parts cleaning plan must be formulated according to the external environment of the power station during safe operation and maintenance. The cleaning process of photovoltaic power station parts is usually divided into three operation processes: sweeping, soil scraping and cleaning. Photovoltaic solar cables, as an important component of photovoltaic modules, will inevitably have inorganic and organic matter such as sand, dust, and mud attached to the surface of photovoltaic cables. However, since solar photovoltaic cables are laid on the back of photovoltaic panels, they cannot be cleaned. On the contrary, the cleaning process of photovoltaic modules will harm the existing photovoltaic solar cables, shorten the life of ordinary photovoltaic solar cables, and create operational risks.

[0003] Summary of the Invention

[0004] In response to the current problem that cleaning of photovoltaic cables may cause harm to them and create operational risks, the present invention provides a self-cleaning photovoltaic cable and a preparation method thereof. By laser etching a three-dimensional structure on the surface of the sheath layer, the cable surface acquires super-hydrophobic properties. Droplets roll on the cable surface, attaching to and carrying away organic and inorganic solid particles, thereby achieving a self-cleaning effect.

[0005] In order to achieve the above object, the present invention provides a method for preparing a self-cleaning photovoltaic cable, wherein the cable comprises a conductor, a halogen-free cross-linked insulation layer and a halogen-free cross-linked sheath layer, and the preparation method comprises the following steps:

[0006] S1. Cover the cable conductor with a halogen-free cross-linked insulation layer and a halogen-free cross-linked sheath layer in sequence, and irradiate the cable;

[0007] S2 laser etches a concentric pattern on the surface of the halogen-free cross-linked jacket layer, wherein the concentric pattern includes a non-etched area and at least two etched areas from the center outward, and the pulse energy of the etched areas gradually increases from the center outward.

[0008] The advantage of the above pattern is that the roughness of different areas gradually increases from the inside to the outside, which is more conducive to water gathering in the central area faster to form water droplets, thereby achieving a better self-cleaning effect.

[0009] The present invention achieves super-hydrophobic properties on the cable surface by laser etching a three-dimensional structure on the surface of the sheath layer. Liquid droplets adhere to and carry away organic and inorganic solid particles on the cable surface through rolling motion, thereby achieving a self-cleaning effect without causing adverse effects of over-crosslinking on the radiation-crosslinked halogen-crosslinked insulation layer and the halogen-free crosslinked sheath layer.

[0010] Specifically, in step S2, the concentric patterns are concentric circles or concentric regular polygons, and the spacing between the patterns is the same. The concentric patterns are conducive to the water gathering into droplets.

[0011] Preferably, the concentric pattern is a square. The square pattern is beneficial for further reducing the contact area between the liquid and the surface, making it easier to form an air film and enhancing the overall hydrophobicity.

[0012] Preferably, in step S2, the concentric pattern includes a non-etching area, a first etching area and a second etching area from the center outward, the focal length of the laser etching is 100 to 300 mm, the scanning speed is 0.6 to 0.8 mm / s, the etching pulse energy of the first etching area is 120 to 125 μJ, and the etching pulse energy of the second etching area is 160 to 165 μJ.

[0013] Specifically, in step S1, the halogen-free cross-linked insulation layer is extruded outside the conductor by a single-screw extruder, the screw temperature is set to 125±10℃, 130±10℃, 135±10℃, 140±10℃, 145±10℃, and its thinnest point thickness is ensured to be ≥0.5mm.

[0014] Specifically, in step S1, the halogen-free cross-linked sheath layer is extruded outside the halogen-free cross-linked insulation layer by a single-screw extruder, and the screw temperature is set to 135±10℃, 140±10℃, 140±10℃, 150±10℃, 150±10℃, 150±10℃, and 150±10℃.

[0015] Specifically, in step S2, the irradiation is: irradiation energy is 1.2-2.4 MeV, operation passes are 24-48, and irradiation dose is 14-15 Mrad.

[0016] A second aspect of the present invention provides a self-cleaning photovoltaic cable produced by the above-mentioned preparation method.

[0017] Through the above technical solution, the present invention achieves the following beneficial effects:

[0018] 1. The present invention laser etches a three-dimensional structure with a gradually increasing roughness from the inside to the outside on the surface of the cross-linked sheath layer, thereby making the cable surface super-hydrophobic. The droplets roll on the cable surface and gather into droplets in the central area, thereby making the cable surface super-hydrophobic. The droplets roll on the cable surface and attach to and carry away organic and inorganic solid particles, achieving a self-cleaning effect and having excellent waterproof properties.

[0019] 2. This photovoltaic cable utilizes physical radiation crosslinking to create crosslinks between the molecular chains. This restricts macromolecular chain slippage and improves resistance to deformation caused by the external environment. Furthermore, the radiation crosslinking process maintains a high degree of crystallinity, resulting in mechanical properties far superior to those achieved with chemical crosslinking. With appropriate irradiation crosslinking, the cable's tensile strength, creep resistance, and modulus are enhanced to varying degrees, with significant improvements in heat resistance and stress cracking resistance. Furthermore, radiation crosslinking, under the action of radiation, initiates the formation of a three-dimensional network structure between the linear polymer bonds via free radicals or ionic bonds, increasing the molecular weight. As the number of crosslinks increases, regional network structures gradually form, ultimately forming an overall network structure. This crosslinked network structure exhibits properties such as solvent insolubility and resistance to melting. The intermolecular gaps in the material are altered to be smaller than those of water molecules. Ultimately, the performance of chemical solvent resistance, certain waterproofness and hydrophobicity is achieved, and the photovoltaic cable can have more complete low-temperature, dynamic penetration ozone resistance, UV (ultraviolet) resistance, acid and alkali test resistance, damp heat test and other characteristics in special outdoor environments, thereby increasing the service life of the cable.

[0020] 3. In a preferred technical solution of the present invention, the concentric pattern is a square. The square pattern is beneficial to further reduce the contact area between the liquid and the surface, making it easier to form an air film and enhance the overall hydrophobicity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a preferred embodiment of the laser etching pattern of the present invention.

[0022] DESCRIPTION OF REFERENCE NUMERALS 1 non-etching region, 2 first etching region, 3 second etching region DETAILED DESCRIPTION

[0023] The following is a detailed description of the specific embodiments of the present invention in conjunction with the examples. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0024] In the following embodiments, the conductor is a TJRX type tinned Category V conductor, the halogen-free cross-linked insulation material includes an XLPO radiation-cross-linked polyolefin insulation material, and the halogen-free cross-linked sheath is an XLPO radiation-cross-linked polyolefin sheath material.

[0025] Example 1

[0026] The specific preparation process of self-cleaning photovoltaic cables is as follows:

[0027] S1. Prepare a stranded conductor;

[0028] S2. Use Φ45+35 single screw extruder to extrude halogen-free cross-linked insulation. Set the screw temperature to 125℃, 130℃, 135℃, 140℃, and 145℃, and ensure that the thickness at the thinnest point is ≥0.5mm;

[0029] S3. Use Φ80 single screw extruder to extrude halogen-free cross-linked sheath, and set the screw temperature to 135℃, 140℃, 140℃, 150℃, 150℃, 150℃, 150℃;

[0030] S4. Irradiate the sheathed cable through a particle accelerator with an irradiation energy of 1.8 MeV, 40 passes, and an irradiation dose of 15 Mrad.

[0031] S5. The irradiated cable sheath surface is laser etched into a pattern as shown in Figure 1, with a focal length of 100 mm and a scanning speed of 0.6 mm / s. The center of the pattern is a non-etched area 1, the pulse energy of the first etched area 2 is 125 μJ, and the pulse energy of the second etched area 3 is 165 μJ.

[0032] Example 2

[0033] The specific preparation process of self-cleaning photovoltaic cables is as follows:

[0034] S1. Prepare a stranded conductor;

[0035] S2. Use Φ45+35 single screw extruder to extrude halogen-free cross-linked insulation. Set the screw temperature to 115℃, 120℃, 125℃, 130℃, and 135℃, and ensure that the thickness at the thinnest point is ≥0.5mm;

[0036] S3 uses a Φ80 single-screw extruder to extrude the halogen-free cross-linked sheath, and the screw temperature is set at 125℃, 130℃, 130℃, 140℃, 140℃, 140℃, 140℃;

[0037] S4. The sheathed cable is irradiated by a particle accelerator with an irradiation energy of 2.4 MeV, 24 passes, and an irradiation dose of 14 Mrad.

[0038] S5. The irradiated cable sheath surface is laser-etched into a pattern as shown in FIG1 . The focal length is 300 mm, the scanning speed is 0.8 mm / s, the center of the pattern is a non-etched area 1, the pulse energy of the first etched area 2 is 120 μJ, and the pulse energy of the second etched area 3 is 160 μJ.

[0039] Example 3

[0040] The specific preparation process of self-cleaning photovoltaic cables is as follows:

[0041] S1. Prepare a stranded conductor;

[0042] S2. Use Φ45+35 single screw extruder to extrude halogen-free cross-linked insulation. Set the screw temperature to 135℃, 140℃, 145℃, 150℃, and 155℃, and ensure that the thickness at the thinnest point is ≥0.5mm;

[0043] S3. Use Φ80 single screw extruder to extrude halogen-free cross-linked sheath, and set the screw temperature to 145℃, 150℃, 150℃, 160℃, 160℃, 160℃, 160℃;

[0044] S4. Irradiate the sheathed cable through a particle accelerator with an irradiation energy of 1.2 MeV, 48 passes, and an irradiation dose of 15 Mrad.

[0045] S5. The irradiated cable sheath surface is laser etched into a pattern as shown in Figure 1, with a focal length of 200 mm and a scanning speed of 0.7 mm / s. The center of the pattern is a non-etched area 1, the pulse energy of the first etched area 2 is 125 μJ, and the pulse energy of the second etched area 3 is 165 μJ.

[0046] Comparative Example 1

[0047] The specific preparation process of self-cleaning photovoltaic cables is as follows:

[0048] S1. Prepare a stranded conductor;

[0049] S2. Evenly mix the XLPE cross-linked polyethylene material and the catalyst, and extrude the cross-linked insulation layer using a Φ45+35 single-screw extruder. Set the screw temperature to 125°C, 130°C, 135°C, 140°C, and 145°C, and ensure that the thickness at the thinnest point is ≥0.5mm;

[0050] S3. Evenly mix the XLPE cross-linked polyethylene material and the catalyst, and extrude the cross-linked sheath layer using a Φ80 single-screw extruder. The screw temperatures are set at 135°C, 140°C, 140°C, 150°C, 150°C, 150°C, and 150°C.

[0051] S4. Irradiate the sheathed cable through a particle accelerator with an irradiation energy of 1.8 MeV, 40 passes, and an irradiation dose of 15 Mrad.

[0052] S5. The cable sheath surface is laser-etched into a pattern as shown in FIG1 , with a focal length of 100 mm and a scanning speed of 0.6 mm / s. The center of the pattern is a non-etched area 1, the pulse energy of the first etched area 2 is 125 μJ, and the pulse energy of the second etched area 3 is 165 μJ.

[0053] Comparative Example 2

[0054] The specific preparation process of self-cleaning photovoltaic cables is as follows:

[0055] S1. Prepare a stranded conductor;

[0056] S2. Use Φ45+35 single screw extruder to extrude halogen-free cross-linked insulation. Set the screw temperature to 125℃, 130℃, 135℃, 140℃, and 145℃, and ensure that the thickness at the thinnest point is ≥0.5mm;

[0057] S3. Use Φ80 single screw extruder to extrude halogen-free cross-linked sheath, and set the screw temperature to 135℃, 140℃, 140℃, 150℃, 150℃, 150℃, 150℃;

[0058] S4. Irradiate the sheathed cable through a particle accelerator with an irradiation energy of 1.8 MeV, 40 passes, and an irradiation dose of 15 Mrad.

[0059] S5. A self-cleaning coating is prepared from the following raw materials in percentage by mass: 40% aqueous polyurethane dispersion, 11.6% acrylic emulsion, 4.4% composite film-forming agent, 0.4% dispersant, 0.3% defoaming agent, 0.1% wetting agent, 2% matting agent, 0.2% leveling agent, 0.2% composite thickener, 4% ethanol, 16.8% pure water, and 20% superhydrophobic additive.

[0060] S6. Spray the above self-cleaning coating evenly on the surface of the cable sheath and dry it with hot air at 60°C.

[0061] Comparative Example 3

[0062] The specific preparation process of photovoltaic cables is as follows:

[0063] S1. Prepare a stranded conductor;

[0064] S2. Use Φ45+35 single screw extruder to extrude halogen-free cross-linked insulation. Set the screw temperature to 125℃, 130℃, 135℃, 140℃, and 145℃, and ensure that the thickness at the thinnest point is ≥0.5mm;

[0065] S3. Use Φ80 single screw extruder to extrude halogen-free cross-linked sheath, and set the screw temperature to 135℃, 140℃, 140℃, 150℃, 150℃, 150℃, 150℃;

[0066] S4. The sheathed cable is irradiated by a particle accelerator with an irradiation energy of 1.8 MeV, 40 passes, and an irradiation dose of 15 Mrad.

[0067] Performance Testing

[0068] The cables prepared in the examples and comparative examples were tested for contact angles, and the results are shown in Table 1.

[0069] Table 1 Contact angle test results

[0070] From the above results, it can be seen that the contact angle of the cable prepared in the embodiment is above 163°, and it has good hydrophobicity, thereby achieving a good self-cleaning effect.

[0071] The contact angle of the cable of Comparative Example 3 without laser etching was 97.0°, indicating no hydrophobicity.

[0072] The contact angle of chemical crosslinking and laser etching (Comparative Example 1) is 156°, and the contact angle of radiation crosslinking and self-cleaning coating is 157.4°. Both have certain hydrophobicity, but the effect is worse than that of the present invention.

[0073] The thermal extension data of the cross-linked sheaths before and after laser etching of Example 1 and Comparative Example 1 were tested, and the results are shown in Table 2.

[0074] Table 2 Thermal extension data of cross-linked sheath before and after laser etching

[0075] By comparing the thermal extension data of the cross-linked sheath before and after laser etching, it can be seen that the variance and standard deviation of the load and permanent deformation data of Example 1 have no obvious changes, while those of Comparative Example 1 have been significantly improved. It can be seen that the data dispersion of Comparative Example 1 has increased, which indicates that optical laser etching causes local over-crosslinking of the chemically cross-linked sheath material, thereby affecting the consistency of the cross-linking degree of the sheath.

[0076] The preferred embodiments of the present invention are described in detail above in conjunction with the embodiments. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0077] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0078] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a self-cleaning photovoltaic cable, characterized in that: The cable comprises a conductor, a halogen-free cross-linked insulation layer and a halogen-free cross-linked sheath layer, and the preparation method comprises the following steps: S1. Cover the cable conductor with a halogen-free cross-linked insulation layer and a halogen-free cross-linked sheath layer in sequence, and irradiate the cable conductor; S2. Laser etching a concentric pattern on the surface of the halogen-free cross-linked sheath layer, wherein the concentric pattern includes a non-etching area and at least two etching areas from the center to the outside, and the pulse energy of the etching area gradually increases from the center to the outside.

2. The preparation method according to claim 1, characterized in that: In step S2, the concentric patterns are concentric circles or concentric regular polygons, and the spacing between each pattern is the same.

3. The preparation method according to claim 2, characterized in that: The concentric pattern is a square.

4. The preparation method according to claim 1, characterized in that: In step S2, the concentric pattern includes a non-etching area, a first etching area and a second etching area from the center to the outside, the focal length of the laser etching is 100-300 mm, the scanning speed is 0.6-0.8 mm / s, the etching pulse energy of the first etching area is 120-125 μJ, and the etching pulse energy of the second etching area is 160-165 μJ.

5. The preparation method according to any one of claims 1 to 4, characterized in that: In step S1, the halogen-free cross-linked insulation layer is extruded outside the conductor by a single-screw extruder, the screw temperature is set to 125±10℃, 130±10℃, 135±10℃, 140±10℃, 145±10℃, and the thickness at the thinnest point is ensured to be ≥0.5mm.

6. The preparation method according to any one of claims 1 to 4, characterized in that: In step S1, the halogen-free cross-linked sheath layer is extruded outside the halogen-free cross-linked insulation layer by a single-screw extruder, and the screw temperature is set to 135±10℃, 140±10℃, 140±10℃, 150±10℃, 150±10℃, 150±10℃, 150±10℃, and 150±10℃.

7. The preparation method according to any one of claims 1 to 4, characterized in that: In step S1, the irradiation is: irradiation energy is 1.2-2.4 MeV, operation passes are 24-48, and irradiation dose is 14-15 Mrad.

8. A self-cleaning photovoltaic cable prepared by the preparation method according to any one of claims 1 to 7.

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