Photovoltaic panel passive cooling system capable of automatically absorbing water, evaporating and cooling based on capillary action

Abstract

The invention discloses a photovoltaic panel passive cooling system capable of automatically absorbing water, evaporating and cooling based on capillary action. The photovoltaic panel passive cooling system comprises a photovoltaic panel, a photovoltaic support, a wicking material, a water supply assembly, a water conveying pipe, a water storage tank and an adjusting and fixing assembly. The photovoltaic panel is fixedly installed through the photovoltaic support, and the installation mode is horizontal, inclined or vertical. The two ends of the water supply assembly are horizontally arranged along the edges of the two sides of the photovoltaic panel. The wicking material is attached to the back surface of the photovoltaic panel, and the lower end of the wicking material extends into the water supply assembly; the water supply assembly is connected with the water storage tank through a water conveying pipe. The adjusting and fixing assembly is connected with the water supply assembly and the photovoltaic panel and used for adjusting the vertical state of the water supply assembly. According to the invention, an energy-saving, water-saving, efficient and reliable photovoltaic panel cooling effect is realized, so that the power generation efficiency of a photovoltaic system is improved and the service life of the photovoltaic system is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic panel cooling, and particularly to a passive cooling system for photovoltaic panels that automatically absorbs water and evaporates for cooling based on capillary action. Background Art

[0002] The power generation efficiency of photovoltaic panels is negatively correlated with the operating temperature. The temperature coefficient of crystalline silicon photovoltaic panels is about -0.25% / °C to -0.5% / °C. In a high-radiation and high-temperature environment, the temperature of photovoltaic panels can reach 60 - 80°C, resulting in a 15% - 25% reduction in power generation efficiency, accelerating the aging of components, causing high-temperature heat loss, and shortening the service life of photovoltaic power generation. Reducing the operating temperature of photovoltaic panels has become an effective way to improve the photoelectric conversion efficiency and extend the service life of photovoltaic power generation. To address the problem of high operating temperature of photovoltaic panels, two types of technologies, active cooling and passive cooling, have been proposed. Active cooling: such as a water circulation system, which has significant effects but requires external energy. Passive cooling: such as natural convection, which has a simple structure but limited effects. Although traditional water film cooling has been widely applied, it still has defects such as high energy consumption, water resource waste, complex maintenance, and unstable cooling. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to propose a passive cooling system for photovoltaic panels that automatically absorbs water and evaporates for cooling based on capillary action. Utilizing the capillary automatic water absorption characteristics of wicking materials, a passive cooling system that automatically absorbs water and evaporates from the lower end of the back of the photovoltaic panel along an inclined plane upward is designed. This system does not require external energy drive, realizes automatic water replenishment on the back of the photovoltaic panel and continuous and stable evaporation cooling, is particularly suitable for power generation and operating temperature management of photovoltaic systems in dry and hot regions, rainy regions, or ice-free regions, effectively solves the technical problems of high input cost, high energy consumption, water resource waste, and inconvenient maintenance management of existing cooling technologies, realizes energy-saving, water-saving, efficient, and reliable cooling effects of photovoltaic panels, and further improves the power generation efficiency and operating life of photovoltaic systems.

[0004] To achieve the above technical objectives, the technical solution adopted by the present invention is as follows: The present invention provides a passive cooling system for photovoltaic panels that automatically absorbs water and evaporates for cooling based on capillary action, including: a photovoltaic panel, a photovoltaic support, a wicking material, a water supply assembly, a water pipe, a water storage tank, and an adjustment and fixing assembly; the photovoltaic panel is fixedly installed through the photovoltaic support, and the installation method is horizontal, inclined, or vertical; both ends of the water supply assembly are horizontally arranged along the two side edges of the photovoltaic panel; the wicking material is attached to the back of the photovoltaic panel, and its lower end extends into the water supply assembly; the water supply assembly is connected to the water storage tank through the water pipe; the adjustment and fixing assembly are respectively connected to the water supply assembly and the photovoltaic panel for adjusting the vertical state of the water supply assembly; The water supply assembly includes a water supply tank, a submerged rod, and a float valve. The water supply tank is of a rectangular parallelepiped structure. The two ends of the water supply tank are horizontally arranged along the two side edges of the photovoltaic panel, and the upper edge of the water supply tank abuts against the side frame of the photovoltaic panel. A long strip-shaped channel is formed on the upper surface of the water supply tank in the horizontal direction and close to the photovoltaic panel for accommodating a wicking material. The submerged rod is installed in the water supply tank. The lower end of the wicking material passes through the channel and enters the water supply tank, and is fixed to the submerged rod. A boss is communicated with the left end of the upper surface of the water supply tank. A flip cover is arranged on the top surface of the boss. The float valve is installed in the boss and is connected to the water storage tank through a water delivery pipe for automatically replenishing water and maintaining a constant water level.

[0005] Further, the wicking material is quick-drying cloth, corduroy cloth or space cotton, and the capillary water absorption height of the wicking material in the vertical direction is not less than 150 mm.

[0006] Further, the wicking material is attached to the back of the photovoltaic panel through thermal conductive silicone grease, and the thermal conductivity of the thermal conductive silicone grease is not less than 1 W / (m·K).

[0007] Further, when the height formed between the photovoltaic panel and the horizontal plane is greater than the capillary water absorption height of the wicking material in the vertical direction, a plurality of water supply assemblies are distributed in a stepped manner along the installation direction of the photovoltaic panel. Each section of wicking material corresponds to a water supply assembly, and the height formed between the effective length from the upper end to the gas-liquid interface in the water supply tank in each section of wicking material and the horizontal plane is less than or equal to the capillary water absorption height of the wicking material in the vertical direction. The water supply assemblies are connected in series through water delivery pipes and share the same water storage tank.

[0008] Further, the adjustment and fixing assembly includes two sticky hooks and two chains. The two sticky hooks are respectively fixed at the two ends of the water supply tank. One end of the chain is fixed to the sticky hook, and the other end is fixed to the edge of the photovoltaic panel for keeping the water supply tank in a vertical state.

[0009] Further, when the installation method is horizontal, the photovoltaic panel is parallel to the ground, and four photovoltaic brackets are respectively installed at the four corners of the photovoltaic panel; When the installation method is inclined, the photovoltaic panel is inclined. The range of the inclination angle a between the photovoltaic panel and the ground is: 0° < a < 90°. Four photovoltaic brackets are respectively installed at the four corners of the photovoltaic panel; When the installation method is vertical, the photovoltaic panel is perpendicular to the ground, and two photovoltaic brackets are respectively installed on both sides of the photovoltaic panel.

[0010] Further, one side of the water storage tank is connected to the water supply tank through a water delivery pipe, and the other side is connected to a water source through a water delivery pipe.

[0011] Further, at least two control valves are further included. The control valves are installed on the water delivery pipe and close to the water storage tank.

[0012] Furthermore, it further includes a support base and a base surface. The support base and the photovoltaic bracket are installed on the base surface, and the water storage tank is installed on the support base; the support base is in an inverted U-shaped structure.

[0013] Adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows: By attaching a wicking material to the back of the photovoltaic panel, the present invention automatically absorbs water from bottom to top by the capillary action of the wicking material, which is different from the conventional water flow cooling that relies on gravity from top to bottom, avoiding excessive consumption of water resources; completely relying on a passive operation mode, the system does not require external energy drive, does not rely on pumps or power devices, and operates autonomously based entirely on physical principles, achieving zero-energy cooling; after the moisture content of the wicking material evaporates and decreases, it can directly absorb water from the water supply tank to replenish water, keeping the material on the back of the photovoltaic panel continuously wet. Through precise water level control and an automatic water replenishment mechanism, the system only consumes the amount of water actually required for evaporation, significantly improving the water resource utilization efficiency, and is especially suitable for photovoltaic system power generation cooling and temperature management in dry and hot areas, rainy areas or ice-free areas; the system has few components, simple connections, no complex mechanical parts, reducing the failure rate and maintenance cost; the water storage tank can collect and utilize non-traditional water resources such as rainwater, reclaimed water, and air-conditioning condensate water; it is applicable to various crystalline silicon photovoltaic systems, and the design parameters can be flexibly adjusted according to different installation scenarios and photovoltaic panel sizes. This system can effectively reduce the operating temperature of the photovoltaic system, improve the power generation efficiency of the photovoltaic panel, has a low input cost, is very convenient for later operation and maintenance management, and has low resource consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0015] Figure 1 It is a schematic diagram of a passive cooling system for inclined (or horizontal) installed photovoltaic panels provided by the present invention.

[0016] Figure 2 It is a schematic diagram of a passive cooling system for vertically installed photovoltaic panels provided by the present invention.

[0017] Figure 3 It is a schematic diagram of the installation of a water supply tank, a float valve and a wicking material provided by the present invention.

[0018] Figure 4 It is an elevation view of the present invention in a state where the wicking material evaporates and dries, the water supply tank is in the process of replenishing water, and the float valve is open.

[0019] Figure 5 It is an elevation schematic diagram provided by the present invention when the wicking material is capillary water-saturated, the water level in the water supply tank is almost constant, and the float valve is closed.

[0020] Figure 6 It is a dimensional schematic diagram of each section of the wicking material when the photovoltaic panel is inclinedly installed provided by the present invention.

[0021] Figure 7 It is a dimensional schematic diagram of each section of the wicking material when the photovoltaic panel is vertically installed provided by the present invention.

[0022] Figure 8 It is a back center temperature test diagram of the photovoltaic panel with the wicking material (flannelette) attached to the back and without the wicking material attached provided by the present invention.

[0023] Figure 9 It is a power generation power test diagram of the photovoltaic panel with the wicking material (flannelette) attached to the back and without the wicking material attached provided by the present invention.

[0024] Description of the reference numerals in the figure: 1 - Photovoltaic panel, 2 - Photovoltaic support, 3 - Wicking material, 4 - Water supply assembly, 41 - Water supply tank, 42 - Submerged rod, 43 - Float valve, 44 - Channel, 45 - Boss, 46 - Flap, 47 - Opening, 5 - Water delivery pipe, 6 - Water storage tank, 7 - Adjusting and fixing assembly, 71 - Hook, 72 - Chain, 8 - Support base, 9 - Base surface, 10 - Control valve. Detailed implementation manners

[0025] The present invention will be further described in detail below in conjunction with the drawings and embodiments. It should be particularly noted that the following embodiments are only used to illustrate the present invention, but do not limit the scope of the present invention. Similarly, the following embodiments are only partial embodiments of the present invention rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0026] Please refer to Figure 1 and Figure 2 A passive cooling system for a photovoltaic panel based on capillary action for automatic water absorption and evaporation cooling, which is used to cool the photovoltaic panel and improve the power generation performance and service life of the photovoltaic panel. It includes: a photovoltaic panel 1, a photovoltaic support 2, a wicking material 3, a water supply assembly 4, a water delivery pipe 5, a water storage tank 6, and an adjusting and fixing assembly 7; The photovoltaic panel 1 is fixedly installed through the photovoltaic support 2, and the installation method can be horizontal, inclined or vertical; both ends of the water supply component 4 are horizontally arranged along the two side edges of the photovoltaic panel 1; among them, the photovoltaic panel 1 is the main structure for cooling, and is made of monocrystalline silicon or polycrystalline silicon. Its size can be customized according to requirements. The photovoltaic panel 1 is fixed by the photovoltaic support 2 and can be connected by screws through triangular components. The photovoltaic support 2 is made of anti-corrosive aluminum alloy or hot-dip galvanized steel material, and the installation angle is optimized and adjusted according to the latitude and lighting conditions of the installation site. As Figure 1 shown, when the photovoltaic panel 1 is installed at a certain angle or horizontally with respect to the horizontal plane, the photovoltaic support 2 is fixed to the installation plane (such as a concrete roof or a ground foundation) through stainless steel expansion bolts (such as M8×80mm). The connection points between the photovoltaic support 2 and the photovoltaic panel 1 are located at the four corners of the photovoltaic panel 1 to ensure no obstruction on the back and provide a flat space for the attachment of the wicking material 3. As Figure 2 shown, when the photovoltaic panel 1 is installed vertically, the photovoltaic supports 2 are placed on both sides of the photovoltaic panel 1, and the photovoltaic supports 2 and the photovoltaic panel 1 are connected by welding and then integrally fixed to the installation plane (such as a wall).

[0027] The wicking material 3 is attached to the back of the photovoltaic panel 1, and its lower end extends into the water supply component 4; the water supply component 4 is connected to the water storage tank 6 through a water delivery pipe 5; the adjustment and fixing component 7 is respectively connected to the water supply component 4 and the photovoltaic panel 1 for adjusting the vertical state of the water supply component 4. The water supply component 4 supplies water to the wicking material 3, and the wicking material 3 automatically absorbs water from bottom to top under capillary action. After the wicking material 3 absorbs water, it absorbs the heat of the photovoltaic panel 1, and the evaporation of water takes away a large amount of heat, thereby evaporatively cooling the photovoltaic panel 1 and reducing the operating temperature of the photovoltaic panel 1. The water evaporated by the wicking material 3 is automatically replenished from the water supply component 4 due to capillary action, forming a continuous passive cooling mechanism.

[0028] The present invention does not require external energy drive to achieve completely automatic water replenishment. When the solar radiation is strong and the temperature is high, more water evaporates and the cooling effect is strong. When the solar radiation is weak and the temperature is low, less water evaporates and the cooling effect becomes weak, thereby realizing real-time climate regulation of the operating temperature of the photovoltaic panel 1. This system is particularly suitable for power generation cooling of photovoltaic panels 1 in dry and hot regions, rainy regions or ice-free regions, and has technical advantages such as water-saving and high efficiency, low input cost, convenient operation and maintenance, and significant improvement in power generation efficiency.

[0029] In this embodiment, as Figure 3As shown, the wicking material 3 is a fabric such as quick-drying cloth, corduroy cloth, or space cotton that has high-efficiency capillary water absorption ability. It can be either an inorganic hydrophilic material or an organic hydrophilic material. The capillary water absorption height of the wicking material 3 in the vertical direction is not less than 150 mm, the thickness is 0.5 mm to 1 mm, the length is greater than the length of the photovoltaic panel 1 (a certain length needs to be reserved to extend into the water supply tank 41 for water absorption), and the width is the same as the width of the photovoltaic panel 1. The wicking material 3 is a functional material with a special microporous structure that can automatically transport liquid from a lower place to a higher place in a directional manner through capillary action without external energy input. Its core characteristics are self-liquid absorption, uniform wetting, and efficient evaporation. The wicking material 3 has the following functional characteristics: (1) It can absorb water from bottom to top through capillary action, and the capillary water absorption height in the vertical direction is at least 150 mm to ensure complete wetting of the back area of the photovoltaic panel 1; (2) The material has good thermal conductivity to ensure efficient heat transfer from the back of the photovoltaic panel 1 to the moisture; (3) It has a long service life, is resistant to ultraviolet radiation, and has good anti-aging performance.

[0030] The wicking material 3 is attached to the back of the photovoltaic panel 1 through thermal conductive silicone grease. The thermal conductivity coefficient of the thermal conductive silicone grease is not less than 1 W / (m·K), and the thickness is 0.5 mm to 1 mm to ensure that the heat generated on the back of the photovoltaic panel 1 can be efficiently conducted to the wicking material 3, improving the cooling efficiency of the system. The wicking material 3 is tightly attached to the back of the photovoltaic panel 1 from top to bottom along the installation direction of the photovoltaic panel 1 through thermal conductive silicone grease, and a certain length extends from the lower end of the wicking material 3. Before attachment, thermal conductive silicone grease with a thickness of about 0.5 mm is evenly coated on the back of the photovoltaic panel 1 to enhance the thermal contact between the wicking material 3 and the back of the photovoltaic panel 1, and the lower end of the wicking material 3 extends beyond the edge to form a hanging part. The water absorption height of the wicking material 3 is determined by the principle of capillary action. According to the capillary phenomenon theory, the rising height of the liquid in the capillary can be expressed as:

[0031] In the formula: is the rising height of the liquid ( ); is the surface tension coefficient of water ( ); is the contact angle between water and the wicking material 3 ( ); is the density of water ( ); is the acceleration due to gravity ( ); is the equivalent capillary radius of the wicking material 3 ( ). In this system, the wicking material 3 optimizes the equivalent capillary radius (Typical value range: 0.1 - 0.5 mm) and hydrophilic property (contact angle 30°), ensuring the capillary water absorption height 150 mm in the vertical direction, so as to wet the back surface of the photovoltaic panel 1 as much as possible. The formula shows that reducing the capillary radius or the contact angle can significantly improve the water absorption capacity, providing a theoretical basis for system design.

[0032] In this embodiment, the water supply component 4 includes a water supply tank 41, a submerged rod 42 and a float valve 43. The water supply tank 41 is of a cuboid structure, and the material is corrosion-resistant PVC or aluminum alloy. The two ends of the water supply tank 41 are horizontally arranged along the two side edges of the photovoltaic panel 1, and the upper edge of the water supply tank 41 abuts against the side frame of the photovoltaic panel 1 to form a closed environment to reduce water evaporation, ensuring that the lower end extension of the wicking material 3 is mostly immersed in water and not exposed, preventing water evaporation loss in the non-functional area; A long strip channel 44 is opened on the upper surface of the water supply tank 41 along the horizontal direction and close to the photovoltaic panel 1, with a width of 1 - 2 cm, for accommodating the wicking material 3. The submerged rod 42 is installed in the water supply tank 41. The lower end of the wicking material 3 passes through the channel 44 and enters the water supply tank 41, and is fixed to the submerged rod 42. The end of the wicking material 3 is weighted or fixed by the submerged rod 42 to ensure that the lower part of the wicking material 3 is immersed in water. When the submerged rod 42 acts as a weight, it can be made of a thin iron rod or iron wire, with a length the same as the width of the wicking material 3, pasted at the end of the downward extension part of the wicking material 3, and its density is greater than that of water, suspended in the water of the water supply tank 41. When the submerged rod 42 acts as a fixing device, it can be made of a plastic rod or a PVC pipe, pasted on the inner wall of the water supply tank 41 to ensure that the wicking material 3 extends downward and is stably immersed in the water of the water supply tank 41. The water supply tank 41 is used to wet the lower end extension part of the wicking material 3, replenish water for the capillary water absorption of the wicking material 3, and further ensure the wetting and evaporation cooling of the back of the photovoltaic panel 1; The left end of the upper surface of the water supply tank 41 is connected to a boss 45. The height of the upper surface of the boss 45 where the float valve 43 is placed is higher than the height of the upper surface of the water supply tank 41. The top surface of the boss 45 is provided with a flip cover 46, and the flip cover 46 is a structure that can be opened and closed. An opening 47 is provided on the side surface of the boss 45 to install the fixed end of the float valve 43. After installation, closing the flip cover 46 on the top surface reduces water evaporation; the float valve 43 is installed in the boss 45 and is connected to the water storage tank 6 through a water delivery pipe 5, which is used for automatic water replenishment and maintaining a constant water level. After calibration, the water level fluctuation range is controlled to be ≤2 mm to ensure that the end of the wicking material 3 is always immersed. The water level in the water supply tank 41 is precisely controlled by the float valve 43, and the water storage tank 6 automatically replenishes water. The float valve 43 is installed at the side wall position of the water supply tank 41 and is connected to the water storage tank 6 through the water delivery pipe 5, which is used for precisely controlling the water level in the water supply tank 41, controlling the liquid level in the water supply tank 41 to maintain a constant state (optimal wetting condition), and ensuring that the extended part of the wicking material 3 is fully wetted; the float valve 43 is made of corrosion-resistant material and has high sensitivity. When the continuous capillary water absorption of the wicking material 3 causes the liquid level in the water supply tank 41 to drop, the float of the float valve 43 sinks, the float valve 43 senses the water level change, and the valve of the float valve 43 automatically opens, introducing water flow from the water storage tank 6 to replenish the water supply tank 41; when the liquid level in the water supply tank 41 returns to the set water level, the valve of the float valve 43 automatically closes, interrupting the water replenishment, forming an automatically balanced water level control system, and maintaining the stable operation of the system.

[0033] In this embodiment, in practical applications, the design of the system needs to specifically determine the number and layout of the water supply tanks 41 according to the installation tilt angle and size of the photovoltaic panel 1. When the height H formed between the photovoltaic panel 1 and the horizontal plane (when the photovoltaic panel 1 is horizontally installed, H = 0; when the photovoltaic panel 1 is inclinedly installed, the height H is related to the length L of the photovoltaic panel 1 and the tilt angle a between the photovoltaic panel 1 and the horizontal plane, that is, H = Lsin a; when the photovoltaic panel 1 is vertically installed, H = L) is not greater than the vertical capillary water absorption height of the wicking material 3 (the maximum height that water can rise from bottom to top), the capillary action of the wicking material 3 can overcome the gravity and distance factors, and realize effective water absorption from a single bottom water supply tank 41 upward to the entire back surface of the photovoltaic panel 1. At this time, a single water supply tank 41 can meet the water supply requirements of the entire system. When the capillary water absorption of a single piece of wicking material 3 can completely cover the back surface of the photovoltaic panel 1, a single water supply component 4 is used to completely wet and evaporate the back of the photovoltaic panel 1.

[0034] When the height H formed between the photovoltaic panel 1 and the horizontal plane is greater than the capillary water absorption height of the wicking material 3 in the vertical direction (since H = 0 when the photovoltaic panel 1 is horizontally installed, so here only the cases of inclined and vertical installation need to be considered), the capillary water supply range of a single water supply tank 41 is limited, making it difficult to ensure that the area of the wicking material 3 far from the water supply tank 41 is fully wetted. After the single wicking material 3 is capillary water-absorbed and infiltrated, it cannot completely cover the back of the photovoltaic panel 1. At this time, multiple water supply components 4 need to be distributed step by step along the installation direction of the photovoltaic panel 1, with each section of the wicking material 3 corresponding to a water supply component 4. Each water supply tank 41 is responsible for wetting the wicking material 3 in its corresponding area, and they work together to ensure that the entire back of the photovoltaic panel 1 obtains complete and uniform wetting and evaporative cooling effects. The height formed between the effective length from the upper end of each section of the wicking material 3 to the gas-liquid interface in the water supply tank 41 and the horizontal plane is less than or equal to the capillary water absorption height of the wicking material 3 in the vertical direction: ① When the photovoltaic panel 1 is installed inclinedly, each section of the wicking material 3 can be divided into two parts. The first is the inclined part of the wicking material 3 that is inclined and attached to the back of the photovoltaic panel 1, and its effective length is l 1, with an inclination angle of a, and this length l 1 forms a height h1 with the horizontal plane = l 1sina; the second is the vertical part of the wicking material 3 whose lower end extends into the water supply tank 41, and its effective length is the length corresponding to the gas-liquid interface in the water supply tank 41 from the bending point of the inclined part and the vertical part l 2, and this length l 2 forms a height h2 with the horizontal plane = l 2, that is, the effective length from the upper end of the wicking material 3 to the gas-liquid interface in the water supply tank 41 ( l 1 + l 2) forms a height (h1 + h2 = l 1sina + l 2) with the horizontal plane. Since the capillary water absorption height of the wicking material 3 in the vertical direction is the maximum height that the water in the water supply tank 41 can rise, it is necessary to ensure that for each section of the wicking material 3, l 1sina + l 2 is less than or equal to the capillary water absorption height of the wicking material 3 in the vertical direction; as Figure 6 shown; ② When the photovoltaic panel 1 is installed vertically, each section of the wicking material 3 can be divided into three parts. The first is the vertical part of the wicking material 3 that is vertically attached to the back of the photovoltaic panel 1, and its effective length is l 3, and this length l 3 forms a height h3 with the horizontal plane = l 3; the second is the inclined part formed by the channel 44 from the vertical part to the upper surface of the water supply tank 41, and its effective length is l 4, with an inclination angle of b in the vertical direction, and this lengthl The height h4 formed by 4 with the horizontal plane = l 4sinb; The third is the vertical part where the wicking material 3 extends from the upper surface of the water supply tank 41 into the water supply tank 41, and its effective length is the length from the bend of the inclined part and the vertical part to the gas-liquid interface in the water supply tank 41 l 5, and this length l The height h5 formed by 5 with the horizontal plane = l 5, that is, the effective length from the upper end of the wicking material 3 to the gas-liquid interface in the water supply tank 41 ( l 3 + l 4 + l 5) The height formed with the horizontal plane (h3 + h4 + h5 = l 3 + l 4sinb + l 5), since the capillary water absorption height of the wicking material 3 in the vertical direction is the maximum height that the water in the water supply tank 41 can rise, therefore, it is necessary to ensure that each section of the wicking material 3 l 3 + l 4sinb + l 5 is less than or equal to the capillary water absorption height of the wicking material 3 in the vertical direction, as Figure 7 shown; Each water supply component 4 is connected in series through a water delivery pipe 5 and shares the same water storage tank 6. Each water supply tank 41 is connected to the water storage tank 6 through the mutually connected water delivery pipe 5, and each is equipped with an independent float valve 43, and the multi-water supply tank 41 system operates efficiently in coordination. Multiple water supply components 4 and wicking materials 3 are used to achieve complete wetting and evaporation on the back of the photovoltaic panel 1.

[0035] In this embodiment, the adjustment and fixing component 7 includes two hooks 71 and two chains 72. The chains 72 can be made of iron chains. The two hooks 71 are respectively fixed at both ends of the water supply tank 41 (upper surface or front surface). One end of the chain 72 is fixed to the hook 71, and the other end is fixed to the edge of the photovoltaic panel 1, which is used to keep the water supply tank 41 in a vertical state, ensuring that when the photovoltaic panel 1 is installed at different inclination angles, the water supply tank 41 can maintain a vertical state. By adjusting the length of the chain 72, it is ensured that the water supply tank 41 is always vertical when the photovoltaic panel 1 is installed at any inclination angle, avoiding the wicking material 3 from detaching from the water surface.

[0036] In this embodiment, when the installation method is horizontal, the photovoltaic panel 1 is parallel to the ground, and the four photovoltaic brackets 2 are respectively installed at the four corners of the photovoltaic panel 1; When the installation method is inclined, the photovoltaic panel 1 is inclined, and the range of the inclination angle a between the photovoltaic panel 1 and the ground is: 0° < a < 90°, and the four photovoltaic brackets 2 are respectively installed at the four corners of the photovoltaic panel 1; When the installation method is vertical, the photovoltaic panel 1 is perpendicular to the ground, and two photovoltaic brackets 2 are respectively installed on both sides of the photovoltaic panel 1.

[0037] In this embodiment, it further includes a support base 8 and a base surface 9. The support base 8 and the photovoltaic bracket 2 are installed on the base surface 9. One end of the photovoltaic bracket 2 is fixed to the photovoltaic panel 1 to support and fix the photovoltaic panel 1, and the other end is fixed to the base surface 9. The base surface 9 can be a flat surface, an inclined surface, or a vertical surface. The water storage tank 6 is installed on the support base 8. The support base 8 is in an inverted U-shaped structure. The support base 8 is used to support the water storage tank 6 and is placed on the base surface 9. The material can be a steel frame or a concrete structure to ensure stable bearing of the weight of the water storage tank 6 and the water in it.

[0038] In this embodiment, one side of the water storage tank 6 is connected to the water supply tank 41 through a water delivery pipe 5, and the other side is connected to a water source through the water delivery pipe 5. It further includes at least two control valves 10, and the control valves 10 are installed on the water delivery pipe 5 and close to the water storage tank 6. When water needs to be added, the control valve 10 can be opened; when the water volume does not need to be increased, the control valve 10 can be closed. The water storage tank 6 can be used to store tap water and reclaimed water, and can also be used to collect and filter non-traditional water resources such as rainwater and air-conditioning condensate water. The water storage tank 6 is a sealed container, and its volume is designed according to actual needs. The recommended volume is 50 - 100L, and the material can be selected from corrosion-resistant HDPE, fiberglass, or polyethylene, and has sun protection performance. The water storage tank 6 is placed on the support base 8 and is connected through two water delivery pipes 5: an upper water delivery pipe 5 (inlet water delivery pipe) is connected to the rainwater collection system or a tap water interface, and a lower water delivery pipe 5 (outlet water delivery pipe) is connected to the float valve 43 and is used to automatically replenish water to the water supply tank 41. A control valve 10 is installed on the water delivery pipe 5 to manually adjust or cut off the water flow.

[0039] As Figure 4 shown, when the temperature of the photovoltaic panel 1 rises, causing the water in the wicking material 3 to evaporate rapidly, the wicking material 3 continuously absorbs water from the water supply tank 41, causing the water level in the water supply tank 41 to drop. At the same time, the float valve 43 senses the water level change and automatically opens, and the water in the water storage tank 6 flows into the water supply tank 41 through the water delivery pipe 5 to timely supplement the water evaporated and lost by the wicking material 3. When the water level in the water supply tank 41 rises to a preset height, the float floats, and the float valve 43 automatically closes to interrupt the water replenishment process ( Figure 5 )

[0040] When the environmental temperature is high and the solar radiation is strong, the evaporation rate of the wicking material 3 increases, the float valve 43 opens more frequently for water replenishment, and the cooling effect of the system is enhanced; when the environmental temperature is low and the solar radiation is weak, the evaporation rate decreases, the float valve 43 opens less frequently for water replenishment, and the cooling effect is appropriately weakened, thereby realizing real-time climate regulation of the operating temperature of the photovoltaic panel 1. This automatic water absorption and replenishment dynamic regulation enables the system to adjust the cooling intensity according to the actual environmental conditions and avoid unnecessary water resource consumption.

[0041] Through the above implementation methods, the system can achieve efficient passive cooling of the photovoltaic panel 1, significantly improve the power generation efficiency and extend the component life, while having the advantages of low maintenance cost, high adaptability and environmental friendliness.

[0042] To test the actual cooling and power increase effects of the present invention, the central temperature and power generation power changes of the backplane of the photovoltaic panel 1 with flannelette attached and without wicking material were actually measured on the roof of a certain building. The selected photovoltaic panel 1 has a rated power generation of 30W, a width of 430mm, is placed on the roof without obstruction at a tilt of 18° towards the due south, and the tilt length is 460mm. The vertical water absorption height of the flannelette of the selected wicking material 3 is 221mm. Therefore, the water absorption length of the photovoltaic panel 1 in the tilt direction is 715.17mm, and setting a single water supply tank 41 can meet the cooling requirements of the photovoltaic panel 1. The central temperature of the backplane and the power generation power are tested with thermocouples and multimeters respectively. The seasons and weather for testing are sunny days in summer. The temperature test period is from 6:00 to 18:00, the power generation power test period is from 9:00 to 16:00, the environmental temperature is between 28 and 35 °C, the relative humidity is in the range of 60 to 75%, and the irradiance on the inclined plane is at most 1050W / m².

[0043] As can be seen from Figure 8 it, the cooling system provided by the present invention can significantly reduce the backplane temperature of the photovoltaic panel 1. The central temperature of the backplane of the photovoltaic panel 1 with flannelette attached can be reduced by up to 18 °C compared with that without the attached material. The cooling effect is good and is better than that of most current cooling methods. At noon, the power generation power of the photovoltaic panel 1 cooled by the system is significantly and continuously higher than that of the photovoltaic panel 1 without cooling, with a maximum power increase of 2.6W and a percentage increase of about 10%, and the power increase effect is obvious ( Figure 9 ).

[0044] As described above, it is only a preferred implementation example of the present invention, and the scope of implementation of the present invention cannot be limited thereby. That is, equivalent changes and modifications made according to the scope of the present invention patent and the content of the specification should still fall within the scope covered by the present invention.

[0045] The above are only some embodiments of the present invention, and thus do not limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present invention.

Claims

1. A passive cooling system for a photovoltaic panel based on capillary action for automatic water absorption and evaporation cooling, characterized in that, Comprising: A photovoltaic panel, a photovoltaic support, a wicking material, a water supply assembly, a water pipe, a water storage tank, and an adjustment and fixing assembly; the photovoltaic panel is fixedly installed through the photovoltaic support, and the installation method is horizontal, inclined or vertical; both ends of the water supply assembly are horizontally arranged along the two side edges of the photovoltaic panel; the wicking material is attached to the back of the photovoltaic panel, and its lower end extends into the water supply assembly; the water supply assembly is connected to the water storage tank through the water pipe; the adjustment and fixing assembly is respectively connected to the water supply assembly and the photovoltaic panel for adjusting the vertical state of the water supply assembly; The water supply assembly includes a water supply trough, a submerged rod, and a float valve. The water supply trough is of a cuboid structure. Both ends of the water supply trough are horizontally arranged along the two side edges of the photovoltaic panel, and the upper edge of the water supply trough abuts against the side frame of the photovoltaic panel; a long strip channel is opened on the upper surface of the water supply trough in the horizontal direction and close to the photovoltaic panel for accommodating the wicking material. The submerged rod is installed in the water supply trough. The lower end of the wicking material passes through the channel and enters the water supply trough and is fixed to the submerged rod; a convex platform is communicated with the left end of the upper surface of the water supply trough. A flip cover is arranged on the top surface of the convex platform. The float valve is installed in the convex platform and is connected to the water storage tank through a water pipe for automatically replenishing water and maintaining a constant water level.

2. The passive cooling system for a photovoltaic panel based on capillary action for automatic water absorption and evaporation cooling as claimed in claim 1, wherein The wicking material is quick-drying cloth, corduroy cloth or space cotton, and the capillary water absorption height of the wicking material in the vertical direction is not less than 150 mm.

3. The passive cooling system for a photovoltaic panel based on capillary action for automatic water absorption and evaporation cooling as claimed in claim 1, wherein The wicking material is attached to the back of the photovoltaic panel through thermal conductive silicone grease, and the thermal conductivity of the thermal conductive silicone grease is not less than 1 W / (m·K).

4. The passive cooling system for a photovoltaic panel based on capillary action for automatic water absorption and evaporation cooling according to claim 2, wherein When the height formed between the photovoltaic panel and the horizontal plane is greater than the capillary water absorption height of the wicking material in the vertical direction, a plurality of water supply assemblies are distributed in a stepped manner along the installation direction of the photovoltaic panel. Each section of wicking material corresponds to one water supply assembly, and the height formed between the effective length from the upper end to the gas-liquid interface in the water supply trough in each section of wicking material and the horizontal plane is less than or equal to the capillary water absorption height of the wicking material in the vertical direction. Each water supply assembly is connected in series through a water pipe and shares the same water storage tank.

5. The passive cooling system for a photovoltaic panel based on capillary action for automatic water absorption and evaporation cooling according to claim 1, characterized in that, The adjustment and fixing assembly includes two hooks and two chains. The two hooks are respectively fixed at both ends of the water supply trough. One end of the chain is fixed to the hook, and the other end is fixed to the edge of the photovoltaic panel for maintaining the vertical state of the water supply trough.

6. The passive cooling system for a photovoltaic panel based on capillary action for automatic water absorption and evaporation cooling as claimed in claim 1, wherein When the installation method is horizontal, the photovoltaic panel is parallel to the ground, and four photovoltaic supports are respectively installed at the four corners of the photovoltaic panel; When the installation method is inclined, the photovoltaic panel is inclined, and the range of the inclination angle a between the photovoltaic panel and the ground is: 0° < a < 90°, and four photovoltaic supports are respectively installed at the four corners of the photovoltaic panel; When the installation method is vertical, the photovoltaic panel is perpendicular to the ground, and two photovoltaic supports are respectively installed on both sides of the photovoltaic panel.

7. The passive cooling system for a photovoltaic panel based on capillary action for automatic water absorption and evaporation cooling according to claim 1, characterized in that, One side of the water storage tank is connected to the water supply trough through a water pipe, and the other side is connected to a water source through a water pipe.

8. The passive cooling system for a photovoltaic panel based on capillary action for automatic water absorption and evaporation cooling as claimed in claim 7, wherein It further includes at least two control valves, and the control valves are installed on the water pipe and close to the water storage tank.

9. The passive cooling system for a photovoltaic panel based on capillary action for automatic water absorption and evaporation cooling according to claim 1, characterized in that It further includes a support base and a base surface. The support base and the photovoltaic support are installed on the base surface, and the water storage tank is installed on the support base; the support base is of an inverted U-shaped structure.

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