Photovoltaic module deashing and cooling system, photovoltaic system and working method

Abstract

The invention relates to a photovoltaic module deashing and cooling system, a photovoltaic system and a working method.The photovoltaic module deashing and cooling system comprises a plurality of nozzles arranged along the edge of the top of a photovoltaic panel, the nozzles are connected with a water supply pipe, the water inlet end of the water supply pipe is connected to a water tank, and a water supply variable frequency pump is installed on the water supply pipe to feed water in the water tank into the nozzles; the system further comprises a water collecting tank arranged on the edge of the bottom of the photovoltaic panel, the water collecting tank is connected with the water tank through a water collecting pipe, and a filtering element is installed on the water collecting pipe. The water supply variable frequency pump and the electric control regulating valve are connected with the control system, the control system can control the frequency of the water supply variable frequency pump and the opening degree of the electric control regulating valve so that the water supply flow and the water supply flow speed of the nozzle can meet the requirement for dust removal or cooling, and the dust removal and cooling system meets the requirements for cooling and dust removal of the photovoltaic panel at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a photovoltaic component dust cleaning and cooling system, a photovoltaic system and a working method. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Photovoltaic power generation uses the photovoltaic effect of semiconductors to directly convert light energy into electrical energy. It mainly consists of three parts: photovoltaic panels, controllers and inverters. According to research, only about 20% of the solar energy absorbed by photovoltaic modules is effectively converted into electrical energy, and the rest is converted into heat energy, which causes the operating temperature of photovoltaic modules to rise, thereby reducing the conversion efficiency of photovoltaic modules; and when the operating temperature reaches the upper limit of the operating temperature of photovoltaic modules, the temperature increase will also accelerate the aging rate of photovoltaic modules, and high temperature will accelerate the thermal degradation of batteries, causing irreversible structural damage to them. On the other hand, when dust particles accumulate on the surface of photovoltaic modules, a layer of dust will be formed. This will not only change the optical properties of the surface of photovoltaic modules and reduce the amount of useful solar radiation reaching the solar cell, but also promote the temperature rise of the module through the shadow effect, causing hot spots. However, all of these will significantly affect the conversion efficiency and service life of photovoltaic modules. Taking crystalline silicon photovoltaic panels as an example, when the temperature exceeds 40°C, the photoelectric conversion efficiency decreases by 0.3%-0.5% for every 1°C increase in surface temperature. After reaching the upper limit of its operating temperature, the aging rate doubles for every 10°C increase. The impact of dust on the power generation efficiency of the components can reach 10%-25%. Therefore, keeping the surface of photovoltaic components clean and controlling the reasonable operating temperature are crucial to improving the power generation efficiency of photovoltaic power stations.

[0004] Patent CN111384894A discloses an automatic spray cleaning system for photovoltaic panels and its working method, which can clean photovoltaic panels with high cleaning efficiency, high degree of automation, convenience and flexibility, and save labor costs. However, the inventor found that in the above patent, only photovoltaic cleaning is considered, and the flow rate and flow rate of the spray cannot be adjusted. If the photovoltaic panel needs to be cooled, the water flow rate and water supply frequency during cleaning are still used. The water flow rate during cleaning is high, the cooling effect is not good, and more water resources are wasted; moreover, continuous spraying is used during cleaning or cooling, and the water loss is large. Continuous spraying will cause water to continue to exist on the surface of the photovoltaic panel. These water flows will affect the amount of solar radiation reaching the photovoltaic panel, thereby affecting the photoelectric conversion efficiency during spraying. Summary of the invention

[0005] In view of the deficiencies in the prior art, an object of the present invention is to provide a photovoltaic module cleaning and cooling system, a photovoltaic system and a working method, which can achieve cleaning and cooling of photovoltaic modules with less water consumption.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a photovoltaic module dust cleaning and cooling system, comprising a plurality of nozzles for being arranged along the top edge of a photovoltaic panel, the nozzles being connected to a water supply pipe, the water inlet end of the water supply pipe being connected to a water tank, a water supply variable frequency pump being installed on the water supply pipe to deliver water in the water tank into the nozzles, an electrically controlled regulating valve being provided downstream of the water supply variable frequency pump, and a water collection tank being arranged at the bottom edge of the photovoltaic panel, the water collection tank being connected to the water tank through a water collection pipe, and a filter element being installed on the water collection pipe;

[0008] The water supply variable frequency pump and the electric control regulating valve are connected to the control system, and the control system can control the frequency of the water supply variable frequency pump and the opening of the electric control regulating valve so that the water supply flow rate and flow rate of the nozzle meet the needs of dust cleaning or cooling.

[0009] Optionally, the nozzle is a flat fan-shaped nozzle.

[0010] Optionally, the bottom groove surface of the water collecting groove is inclined to guide the collected water into the water collecting pipe.

[0011] Optionally, a flow detection element is also installed on the water supply pipe, and the flow detection element is connected to the control system.

[0012] Optionally, the water tank is also connected to a water supply pipe, a water supply pump is installed on the water supply pipe, an electrically controlled regulating valve installed on the water supply pipe is provided downstream of the water supply pump, and both the water supply pump and the electrically controlled regulating valve are connected to a control system.

[0013] Optionally, a liquid level detection element is installed in the water tank, and the liquid level detection element is connected to a control system.

[0014] In the second aspect, an embodiment of the present invention provides a photovoltaic system, including a photovoltaic panel, which is connected to the top end of a plurality of supporting mechanisms. The photovoltaic panel is also provided with a dust accumulation detection element and a temperature detection element connected to a control system. The photovoltaic panel also includes the photovoltaic component cleaning and cooling system described in the first aspect, wherein a plurality of nozzles are arranged at the top edge of the photovoltaic panel, and a water collecting trough is fixed to the bottom edge of the photovoltaic panel.

[0015] Optionally, baffles are provided at the top edge and two side edges of the photovoltaic panel, and the nozzle is located below the baffles at the top edge;

[0016] Optionally, the baffle at the top edge is a flat baffle, and the baffle at the side edge is an arc-shaped baffle convex toward the outside.

[0017] In a third aspect, an embodiment of the present invention provides a working method of the photovoltaic system according to the second aspect:

[0018] When the dust accumulation detection element detects that the dust accumulation degree of the photovoltaic panel exceeds the set dust accumulation safety threshold and the photovoltaic panel temperature detected by the temperature detection element does not exceed the temperature safety threshold, or when the dust accumulation detection element detects that the dust accumulation degree of the photovoltaic panel exceeds the set dust accumulation safety threshold and the photovoltaic panel temperature detected by the temperature detection element exceeds the temperature safety threshold, the control system controls the water supply variable frequency pump to operate at a first frequency, controls the electric control regulating valve on the water supply pipe to reach a first opening, and the nozzle intermittently sprays water to the photovoltaic panel at a first water flow rate and a first water flow rate to clean the dust;

[0019] When the temperature detection element detects that the temperature of the photovoltaic panel exceeds the set temperature safety threshold and the dust accumulation detection element detects that the dust accumulation degree of the photovoltaic panel does not exceed the set dust accumulation safety threshold, the control system controls the water supply variable frequency pump to operate at a second frequency, controls the electric control regulating valve on the water supply pipe to reach a second opening, and the nozzle intermittently sprays water to the photovoltaic panel at a second water flow rate and a second water flow rate to cool it down;

[0020] The first frequency is greater than the second frequency, and the first opening is less than the second opening.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. The photovoltaic module cleaning and cooling system and photovoltaic system of the present invention require a larger water flow rate and a higher water flow rate in the cleaning mode to achieve effective dust removal; in the cooling mode, a smaller water flow rate and a lower water flow rate are required to achieve uniform and efficient cooling. Therefore, a water supply frequency conversion pump and an electronically controlled regulating valve are provided on the water supply pipe. According to the cooling temperature and dust accumulation of the photovoltaic panel, the control system can control the water supply flow rate by adjusting the operating frequency of the water supply frequency conversion pump to meet the flow requirements in different modes; by adjusting the opening of the valve, the water supply flow rate can be controlled to optimize the cleaning and cooling effects. The combination of the frequency conversion water supply pump and the electronically controlled regulating valve meets the needs of cleaning or cooling, and realizes the maximum utilization of water resources and reduces the waste of water resources.

[0023] 2. In the photovoltaic module dust cleaning and cooling system and photovoltaic system of the present invention, the water supply frequency conversion pump can only be roughly adjusted and the adjustment response speed is slow, while the electric control valve can be accurately regulated and the response speed is fast. The combination of the two can realize accurate and rapid adjustment of the spray flow rate and flow rate. This flexible control strategy ensures that under different operating conditions, efficient, energy-saving and water-saving photovoltaic panel maintenance can be achieved. Moreover, the frequency conversion water supply pump can control the flow rate by adjusting the speed, which can reduce the pressure fluctuation caused by the sudden opening or closing of the electric control valve. Moreover, the water supply frequency conversion pump adjusts the operating speed according to actual needs. Compared with traditional pumps, the energy efficiency of the entire system is improved, and the energy saving effect can reach 10%-80%.

[0024] 3. The working method of the photovoltaic module cleaning and cooling system of the present invention adopts intermittent spraying during cleaning and cooling, that is, spray-stop-spraying mode operation, and spraying is performed only when necessary, which significantly reduces the use of water resources. Compared with the traditional continuous spraying system, water resources can be saved, and the water saving effect can reach 30%-80%. At the same time, the mechanical wear of the pipeline, pump and valve caused by the operation of the system is reduced, the service life of the equipment is extended and the maintenance cost is reduced. Through intermittent spraying on the front of the photovoltaic module, the continuous presence of spray water on the surface of the photovoltaic panel is avoided, which can both clean and cool. Compared with the system with only cleaning and no cooling, the photoelectric conversion efficiency can be increased by 0.5%-5%; compared with the system with only cooling and no cleaning, the photoelectric conversion efficiency can be increased by 0.5%-10%.

[0025] 4. The photovoltaic module dust cleaning and cooling system and photovoltaic system of the present invention are provided with a water collecting tank, a filter element and a water collecting pipe, which can collect the water after flushing or cooling and send it into the water tank again, thereby realizing the recycling of water, saving resources and reducing the cost of cleaning and cooling the photovoltaic modules.

[0026] 5. The photovoltaic module dust cleaning and cooling system and photovoltaic system of the present invention adopt a flat fan-shaped nozzle, which ensures uniform water coverage and avoids local overheating. At the same time, the droplets sprayed from the flat fan-shaped nozzle can form a fan-shaped plane, preventing the spray water from splashing out of the surface of the photovoltaic module and dripping to the ground to cause a waste of water resources. The flat nozzle is not easy to be clogged, and the maintenance cost is low in actual application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0028] Figure 1 It is a schematic diagram of the overall structure of Embodiment 1 of the present invention;

[0029] Figure 2 This is a schematic diagram of the nozzle structure of Example 1 of the present invention;

[0030] Figure 3 This is a schematic diagram of the nozzle spraying state of Example 1 of the present invention;

[0031] Figure 4 Schematic diagram of the distribution of nozzles on the edge of a photovoltaic panel in Example 1 of the present invention;

[0032] Figure 5 Schematic diagram of the cooperation between the nozzle and the upper edge baffle of the photovoltaic panel in Embodiment 2 of the present invention;

[0033] Figure 6 This is a schematic diagram of the explosion of the cooperation between the photovoltaic panel and the baffle in Embodiment 2 of the present invention;

[0034] Figure 7 This is a schematic diagram of the water collection tank structure of Embodiment 2 of the present invention;

[0035] Figure 8 This is a front view of the water collecting tank in Embodiment 2 of the present invention;

[0036] Fig. 9 It is a schematic diagram of the end face of the water collecting tank in Embodiment 2 of the present invention, which is away from the water collecting pipe;

[0037] Fig.10 It is a schematic diagram of the end surface of the water collecting tank close to one end of the water collecting pipe in Embodiment 2 of the present invention;

[0038] Fig.11 This is a top view of the water collection tank in Embodiment 2 of the present invention;

[0039] Among them, 1. Flat baffle, 2. Nozzle, 3. Spray water, 4. Arc plate, 5. Temperature and dust accumulation monitoring point, 6. Water baffle, 7. Water collection trough, 8. Concrete foundation, 9. Support column, 10. Water collection pipe, 11. Filter element, 12. Liquid level sensor, 13. Water tank, 14. Second electric control regulating valve, 15. Second water supply frequency conversion pump, 16. Water supply pipe, 17. First water supply frequency conversion pump, 18. First electric control regulating valve, 19. Water supply pipe, 20. Electromagnetic flow meter, 21. Photovoltaic panel. DETAILED DESCRIPTION

[0040] Example 1

[0041] This embodiment provides a photovoltaic module dust cleaning and cooling system, such as Figure 1As shown, it includes a plurality of nozzles 2, and the plurality of nozzles 2 are all connected to a water supply pipe 19. The plurality of nozzles 2 are used to be arranged at the upper edge of a photovoltaic panel 21, and can spray spray water 3 for cooling and cleaning onto the surface of the photovoltaic panel 21. The water inlet end of the water supply pipe 19 is connected to a water tank 13, and the water tank 13 is used to hold water for cooling and cleaning. A first water supply variable frequency pump 17 is installed on the water supply pipe 19, and the first water supply variable frequency pump 17 can drive the water in the water tank 13 to enter the nozzle 2 through the water supply pipe 19, and then be sprayed out by the nozzle 2. The first water supply variable frequency pump 17 is connected to a control system, and the control system can control the working frequency of the first water supply variable frequency pump 17, thereby adjusting the water supply flow rate of the nozzle 2.

[0042] Along the water supply direction of the water supply pipe, a first electrically controlled regulating valve 18 is installed on the water supply pipe downstream of the first water supply variable frequency pump 17. The first electrically controlled regulating valve 18 is connected to the control system. The control system can adjust the opening of the first electrically controlled regulating valve 18, thereby realizing the adjustment of the water supply flow rate of the nozzle 2.

[0043] The first electrically controlled regulating valve 18 can be an existing electrically controlled regulating valve, which will not be described in detail here.

[0044] Furthermore, along the water supply direction in the water supply pipe 19, a flow detection element is installed on the water supply pipe 19 downstream of the first electrically-controlled regulating valve 18. In this embodiment, the flow detection element uses an electromagnetic flowmeter 20, which is used to detect the flow rate of the water supply in the water supply pipe 19. The electromagnetic flowmeter 20 is connected to the control system and can transmit the detected flow information to the control system.

[0045] In this embodiment, Figure 2-Figure 3 As shown, the nozzle 2 adopts the existing flat fan-shaped nozzle, and the spray angle α is 15°-160°. The nozzle 2 can adopt the existing nozzle, and its specific structure is not described in detail here. The nozzle 2 adopts a flat fan-shaped nozzle to ensure the uniformity of water coverage and avoid local overheating. At the same time, the droplets sprayed by the flat fan-shaped nozzle can form a fan-shaped plane to prevent the spray water from splashing out of the surface of the photovoltaic module and dripping to the ground to cause water waste. The flat nozzle is not easy to be blocked, and the maintenance cost is low in actual application.

[0046] The spray angle of a flat fan nozzle is related to the impact force. The smaller the angle, the stronger the impact force; the larger the angle, the wider the spray coverage, but the impact force will be relatively weakened.

[0047] The photovoltaic module dust cleaning and cooling system also includes a water collecting tank 7, the top of which is open and one side of the top is connected to the photovoltaic panel to collect the spray water of the photovoltaic panel; the bottom shape of the water collecting tank 7 can be a V-shaped structure, a U-shaped structure or a square structure.

[0048] The water collecting trough 7 is used to be fixed on the bottom edge of the photovoltaic panel 21 .

[0049] One end of the water collecting trough 7 is connected to one end of the water collecting pipe 10, and the other end of the water collecting pipe 10 is connected to the water tank 13. The water collecting trough 7 is used to collect the water after cleaning and cooling that slides down the surface of the photovoltaic panel, and the water collecting pipe 10 is used to guide the collected water in the water collecting trough 7 into the water tank 13 for reuse.

[0050] A filter element 11 is installed on the water receiving pipe 10. The filter element 11 can be an existing filter and is used to filter the water flowing through the water receiving pipe 10 to remove suspended matter, impurities and dust contained in the water.

[0051] In this embodiment, Figure 7-Figure 11 As shown, the bottom surface of the water collecting trough 7 is inclined, and the height of the end away from one end of the water collecting pipe is higher than the height of the other end. This arrangement makes it convenient to guide the water in the water collecting trough 7 into the water collecting pipe.

[0052] The angle β between the bottom surface of the water collecting tank 7 and the horizontal plane is 1.5°-20°, and those skilled in the art can set it according to actual needs.

[0053] Preferably, the straight-line distances h1 and h2 between the top and bottom surfaces at both ends of the water collecting trough 7 are both 10 cm-50 cm, and those skilled in the art can set them according to actual needs, where h2 is the distance between the top and bottom surfaces of the end of the water collecting trough 7 close to the water collecting pipe 10, and h1 is the distance between the top and bottom surfaces of the other end of the water collecting trough, and h2 is greater than h1.

[0054] The top edge of the water collecting tank 7 away from the photovoltaic panel is provided with a water retaining plate 6 extending toward the inner side of the water collecting tank 7, which can effectively prevent the cooling and cleaning circulating water from splashing due to excessive flow rate when entering the water collecting tank 7.

[0055] The water retaining plate 6 is provided with a certain inclination angle, and the angle between the water retaining plate 6 and the horizontal plane is 10°-170°, and those skilled in the art can set it according to actual needs.

[0056] In this embodiment, the top width b of the water collecting tank 7 is 5 cm-50 cm, and those skilled in the art can set it according to actual needs.

[0057] The water collecting tank 7 is made of durable and corrosion-resistant materials, such as stainless steel, fiberglass or plastic, etc. Those skilled in the art can choose according to actual needs.

[0058] The water tank 13 is also connected to a water replenishment pipe 16, which is used to connect to a water source and replenish the water tank 13. A water replenishment pump is installed on the water replenishment pipe 16. Preferably, the water replenishment pump adopts a second water supply variable frequency pump 15. Along the water replenishment direction of the water replenishment pipe 16, a second electrically controlled regulating valve 14 is installed on the water replenishment pipe downstream of the second water supply variable frequency pump 15. The second water supply variable frequency pump 15 and the second electrically controlled regulating valve 14 are both connected to the control system, and their operations are controlled by the control system.

[0059] Furthermore, a liquid level detection element is installed in the water tank 13 for detecting the water level in the water tank. The liquid level detection element can be an existing liquid level sensor 12. The liquid level sensor 12 is connected to the control system and can transmit the detected water level information of the water tank to the control system.

[0060] The control system includes a controller 22, which has a data acquisition input terminal 23, which is connected to the electromagnetic flowmeter 10 and the liquid level sensor 12 through a signal line. The controller 22 has a control signal output terminal 24, which is connected to the first water supply variable frequency pump 17, the second water supply variable frequency pump 15, the first electronically controlled regulating valve 18 and the second electronically controlled regulating valve 14 through a signal line.

[0061] Example 2

[0062] This embodiment provides a photovoltaic system, such as Figure 1 As shown, it includes a photovoltaic panel 21, and the photovoltaic panel 21 is connected to a plurality of supporting mechanisms. The bottom of the supporting mechanism is used to cooperate with the ground foundation to support the photovoltaic panel. In this embodiment, the supporting mechanism includes a concrete foundation 8, and the concrete foundation 8 cooperates with the ground foundation. The concrete foundation 8 is fixed to the bottom end of the support column 9, and the top end of the support column 9 is fixed to the photovoltaic panel 21 to support the photovoltaic panel 21.

[0063] It also includes the photovoltaic module dust cleaning and cooling system described in Example 1, such as Figure 4 As shown, the multiple nozzles 2 are arranged at the upper edge of the photovoltaic panel 21. Preferably, the spacing between adjacent nozzles is 10cm-140cm. Such a spacing can ensure that the area covered by the nozzles is neither too dense nor too sparse, thereby achieving uniform spraying and cleaning.

[0064] One side edge of the top of the water collecting tank 7 is fixedly connected to the lower edge of the photovoltaic panel 21 .

[0065] Furthermore, the upper edge and two side edges of the photovoltaic panel 21 are provided with baffles, which can effectively prevent the circulating spray water from splashing out of the surface of the photovoltaic module and dripping onto the ground during the spraying and flowing process, causing water waste.

[0066] In this embodiment, Figure 5 As shown, the baffle on the upper edge of the photovoltaic panel is a plane baffle 1, and the nozzle 2 is located below the plane baffle. Along the surface direction of the photovoltaic panel 21, the distance D between the plane baffle 1 and the nozzle 2 is 3cm-20cm.

[0067] like Figure 6 As shown, the baffles at the two side edges of the photovoltaic panel 21 are arc-shaped plates 4 convex toward the outside.

[0068] In some other embodiments, the baffle may also be a corrugated plate.

[0069] The height H of the baffle is 5 cm-20 cm to ensure that it does not affect the photovoltaic panel 21 from receiving solar radiation.

[0070] The baffle can be set to prevent the spray water from splashing out of the surface of the photovoltaic panel 21 and dripping onto the ground, causing a waste of water resources.

[0071] The photovoltaic panel 1 is also provided with a plurality of temperature detection elements on its surface. The temperature detection elements are temperature sensors. The temperature sensors are connected to the data acquisition input terminal 23 of the controller and can transmit the collected temperature information of the photovoltaic panel surface to the controller.

[0072] The photovoltaic panel is also provided with a dust accumulation detection element, which can adopt an existing photovoltaic panel dust accumulation monitoring system, such as the YGF-1 photovoltaic power station component dust monitoring system or the Dust IQ dust monitoring system or the PV dust monitoring system or the ZTDM1X series dust accumulation sensor or the SR photovoltaic power station dust monitoring system. Existing technology can be used and will not be described in detail here. The dust accumulation detection element is connected to the data acquisition input terminal of the controller and can transmit the collected dust accumulation information to the controller.

[0073] A plurality of temperature and dust accumulation monitoring points 5 distributed in an array are formed on the surface of the photovoltaic panel by means of temperature sensors and dust accumulation detection elements.

[0074] Example 3

[0075] This embodiment provides a working method of the photovoltaic system described in Embodiment 2:

[0076] The dust accumulation safety threshold and the temperature safety threshold are set in advance in the controller 22 .

[0077] The temperature sensor and the dust accumulation detection element detect the temperature and the dust accumulation degree on the surface of the photovoltaic panel 21 in real time.

[0078] When the temperature information detected by the temperature sensor is not greater than the set temperature safety threshold, and the dust accumulation detected by the dust accumulation detection element is not greater than the set dust accumulation safety threshold, the dust cleaning and cooling system does not work.

[0079] When the temperature information detected by the temperature sensor is greater than the set temperature safety threshold, and the dust accumulation detected by the dust accumulation detection element is not greater than the set dust accumulation safety threshold, the control system controls the first water supply frequency conversion pump 17 to operate at the second frequency, and controls the first electronically controlled regulating valve 18 to the second opening, so that the nozzle 2 intermittently sprays water to the surface of the photovoltaic panel at the second water supply flow rate and the second water supply flow rate, starts the cooling mode, and cools the photovoltaic panel 21.

[0080] When the dust accumulation detection element detects that the set dust accumulation level is greater than the dust accumulation safety threshold, and the temperature detected by the temperature sensor is not greater than the set temperature safety threshold, the control system controls the first water supply frequency conversion pump 17 to operate at a first operating frequency, and controls the first electronically controlled regulating valve 18 to a first opening, so that the nozzle 2 intermittently sprays water to the surface of the photovoltaic panel at a first water supply flow rate and a first water supply flow rate, starts the dust cleaning mode, and cleans the surface of the photovoltaic panel.

[0081] When the dust accumulation degree detected by the dust accumulation detection element is greater than the set dust accumulation safety threshold, and the temperature detected by the temperature sensor is greater than the set temperature safety threshold, it works in the cleaning mode. The control system controls the first water supply frequency conversion pump 17 to operate at the first operating frequency, and controls the first electronically controlled regulating valve 18 to the first opening, so that the nozzle 2 intermittently sprays water to the surface of the photovoltaic panel at the first water supply flow rate and the first water supply flow rate, starts the cleaning mode, and cleans and cools the surface of the photovoltaic panel.

[0082] In this embodiment, the first frequency is greater than the second frequency, and the first opening is smaller than the second opening, so that in the cooling mode, a smaller water flow rate and a lower water flow rate are obtained to achieve uniform and efficient cooling; and in the cleaning mode, a larger water flow rate and a higher water flow rate are obtained to effectively remove dust and avoid splashing.

[0083] In this embodiment, the first frequency, the second frequency, the first opening, and the second opening can be set according to actual working conditions and will not be described in detail here.

[0084] In this embodiment, intermittent water spraying is adopted, and the water spraying time and the stop spraying time can be the same or different. Preferably, in the cooling mode, the water spraying time and the stop spraying time are 100s-4000s, and those skilled in the art can set it according to actual needs. The stop spraying time in the dust cleaning mode is 1 day-30 days, and those skilled in the art can set it according to actual needs.

[0085] The intermittent spraying, i.e. spray-stop-spraying mode, is used to spray only when necessary, which significantly reduces the use of water resources. Compared with the traditional continuous spraying system, water resources can be saved, and the water saving effect can reach 30%-80%. At the same time, the mechanical wear of pipes, pumps and valves caused by system operation is reduced, the service life of the equipment is extended and the maintenance cost is reduced. Through intermittent spraying on the front of the photovoltaic module, the continuous presence of spray water on the surface of the photovoltaic panel is avoided, which can be used for both cleaning and cooling. Compared with the system with only cleaning and no cooling, the photoelectric conversion efficiency can be increased by 0.5%-5%; compared with the system with only cooling and no cleaning, the photoelectric conversion efficiency can be increased by 0.5%-10%.

[0086] In this embodiment, due to the use of intermittent spraying, during the opening and closing process of the first electrically-controlled regulating valve, the first variable frequency water supply pump is also started or shut down synchronously. The first variable frequency water supply pump can start and stop accordingly with the opening and closing process of the first electrically-controlled regulating valve, thereby adjusting the water flow rate during the opening and closing process of the first electrically-controlled regulating valve, and reducing the pressure fluctuation caused by the sudden opening or closing of the electrically-controlled regulating valve.

[0087] During the entire working process, the water flow rate of the water supply pipe can be collected in real time through the electromagnetic flowmeter 20 to monitor the water supply flow rate of the entire dust cleaning and cooling system.

[0088] The nozzle 2 sprays water evenly onto the surface of the photovoltaic panel, which not only effectively removes the dust accumulated on the surface of the photovoltaic panel 21, but also realizes the cooling of the photovoltaic panel through the evaporation of water and the heat exchange between the water and the surface of the photovoltaic panel 21, optimizes the thermal management of the photovoltaic module, improves the photoelectric conversion efficiency, and prolongs the service life of the photovoltaic module.

[0089] The unevaporated water on the surface of the photovoltaic panel 21 slides down to the water collecting tank 7, flows along the water collecting tank 7 into the water collecting pipe 10, and then passes through the filter to filter the suspended matter and impurities therein. Then the filtered water flows into the water tank 13 for recycling, saving water resources.

[0090] The liquid level sensor 12 detects the water level in the water tank in real time. When the water level in the water tank 13 is lower than the set value, the control system controls the second water supply frequency conversion pump 15 to work, and opens the second electronically controlled regulating valve 14 to replenish water in the water tank 13 until the water level in the water tank 13 reaches a safe water level. Then the control system stops the second water supply frequency conversion pump 15, closes the second electronically controlled regulating valve 14, and replenishes the water lost due to evaporation, sewage discharge or system leakage through the water replenishment pipe 10.

[0091] The cleaning and cooling working method of the photovoltaic system of this embodiment requires a larger water flow rate and a higher water flow rate in the cleaning mode to achieve effective dust removal; in the cooling mode, a smaller water flow rate and a lower water flow rate are required to achieve uniform and efficient cooling. Therefore, a water supply frequency conversion pump and an electronically controlled regulating valve are provided on the water supply pipe. According to the temperature drop and dust accumulation of the photovoltaic panel, the control system can control the water supply flow rate by adjusting the operating frequency of the water supply frequency conversion pump to meet the flow requirements in different modes; by adjusting the opening of the valve, the water supply flow rate can be controlled to optimize the cleaning and cooling effects. The combination of the variable frequency water supply pump and the electronically controlled regulating valve meets the needs of cleaning or cooling, and realizes the maximum utilization of water resources and reduces the waste of water resources.

[0092] In addition, the water supply variable frequency pump can only be roughly adjusted and has a slow response speed, while the electric control valve can be precisely controlled and has a fast response speed. The combination of the two can achieve accurate and rapid adjustment of the spray flow and flow rate. This flexible control strategy ensures that under different operating conditions, efficient, energy-saving and water-saving photovoltaic panel maintenance can be achieved. The water supply variable frequency pump adjusts the operating speed according to actual needs. Compared with traditional pumps, it improves the energy efficiency of the entire system, and the energy saving effect can reach 10%-80%.

[0093] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A photovoltaic module dust cleaning and cooling system, characterized in that: It includes a plurality of nozzles for being arranged along the top edge of the photovoltaic panel, the nozzles are connected to a water supply pipe, the water inlet end of the water supply pipe is connected to a water tank, a water supply variable frequency pump is installed on the water supply pipe to deliver water in the water tank to the nozzles, an electric control regulating valve is provided downstream of the water supply variable frequency pump, and it also includes a water collection tank for being arranged at the bottom edge of the photovoltaic panel, the water collection tank is connected to the water tank through a water collection pipe, and a filter element is installed on the water collection pipe; The water supply variable frequency pump and the electric control regulating valve are connected to the control system, and the control system can control the frequency of the water supply variable frequency pump and the opening of the electric control regulating valve so that the water supply flow rate and flow rate of the nozzle meet the needs of dust cleaning or cooling.

2. A photovoltaic module cleaning and cooling system as claimed in claim 1, characterized in that: The nozzle is a flat fan-shaped nozzle.

3. A photovoltaic module cleaning and cooling system as claimed in claim 1, characterized in that: The bottom groove surface of the water collecting groove is inclined to guide the collected water into the water collecting pipe.

4. A photovoltaic module cleaning and cooling system as claimed in claim 1, characterized in that: A flow detection element is also installed on the water supply pipe, and the flow detection element is connected to the control system.

5. A photovoltaic module cleaning and cooling system as claimed in claim 1, characterized in that: The water tank is also connected to a water supply pipe, on which a water supply pump is installed, and an electrically controlled regulating valve installed on the water supply pipe is provided downstream of the water supply pump, and both the water supply pump and the electrically controlled regulating valve are connected to a control system.

6. A photovoltaic module cleaning and cooling system as claimed in claim 1, characterized in that: A liquid level detection element is installed in the water tank, and the liquid level detection element is connected to the control system.

7. A photovoltaic system, comprising a photovoltaic panel, wherein the photovoltaic panel is connected to the top of a plurality of supporting mechanisms, and the photovoltaic panel is also provided with a plurality of temperature detection elements and dust accumulation detection elements connected to a control system, and further comprising the photovoltaic module cleaning and cooling system as described in any one of claims 1 to 6, wherein a plurality of nozzles are arranged at the top edge of the photovoltaic panel, and a water collecting trough is fixed to the bottom edge of the photovoltaic panel.

8. The photovoltaic system according to claim 7, characterized in that: The top edge and two side edges of the photovoltaic panel are provided with baffles, and the nozzle is located below the top edge baffle.

9. The photovoltaic system according to claim 7, characterized in that: The baffle plate at the top edge is a plane baffle plate, and the baffle plate at the side edge is an arc-shaped baffle plate convex toward the outside.

10. A photovoltaic system operating method according to claim 7, characterized in that: When the dust accumulation detection element detects that the dust accumulation degree of the photovoltaic panel exceeds the set dust accumulation safety threshold and the photovoltaic panel temperature detected by the temperature detection element does not exceed the set temperature safety threshold, or when the dust accumulation detection element detects that the dust accumulation degree of the photovoltaic panel exceeds the set dust accumulation safety threshold and the photovoltaic panel temperature detected by the temperature detection element exceeds the temperature safety threshold, the control system controls the water supply variable frequency pump to operate at a first frequency, controls the electric control regulating valve on the water supply pipe to reach a first opening, and the nozzle intermittently sprays water to the photovoltaic panel at a first water flow rate and a first water flow rate to clean the dust; When the temperature detection element detects that the temperature of the photovoltaic panel exceeds the set temperature safety threshold and the dust accumulation detection element detects that the dust accumulation degree of the photovoltaic panel does not exceed the set dust accumulation safety threshold, the control system controls the water supply variable frequency pump to operate at a second frequency, controls the electric control regulating valve on the water supply pipe to reach a second opening, and the nozzle intermittently sprays water to the photovoltaic panel at a second water flow rate and a second water flow rate to cool it down; The first frequency is greater than the second frequency, and the first opening is less than the second opening.

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