Greenhouse heat storage and preservation system based on photovoltaic photo-thermal and working method thereof

Abstract

A greenhouse heat storage and insulation system based on photovoltaic photo-thermal and its working method belong to the field of comprehensive utilization of solar photoelectric and photo-thermal technology. In the system, the heat generated by photovoltaic power generation is directly used as the heat source of the heat storage water tank, reducing the electric load and investment cost of photovoltaic power generation. The heat storage water tank and the electric heating water tank are adopted, realizing the use of daytime solar photovoltaic photo-thermal for night insulation. According to the structural characteristics of the greenhouse, the phase change heat collecting plate is arranged on the north wall, the reasonable matching between photovoltaic electric energy and photo-thermal heat energy is realized by increasing the photo-thermal heat, the efficient use of the greenhouse space is realized by utilizing the vertical wall space of the north wall; the drip irrigation device is used for crop root insulation, improving the heat transfer efficiency and insulation effect.

Description

TECHNICAL FIELD

[0001] The present application relates to a photovoltaic photothermal-based greenhouse heat storage and insulation system and its working method, belonging to the field of comprehensive utilization of solar photovoltaic and photothermal technology. TECHNICAL BACKGROUND

[0002] With the continuous development of science and technology, the traditional agricultural production mode has been unable to meet the needs of the development of modern civilization. As a new type of agricultural facility, greenhouse has attracted much attention due to its green and low-carbon, low price and wide application. In cold regions in winter or in the night when the temperature is relatively low, the temperature in the greenhouse cannot meet the needs of crop growth relying on solar energy alone, and it is necessary to use biomass heating, coal heating and electric heating to ensure the normal growth of crops in the greenhouse. These heating methods increase the cost of fuel, labor and equipment, and the combustion of biomass and coal also brings safety hazards and environmental pollution. Therefore, it is necessary to develop a low-cost greenhouse heating method.

[0003] Solar energy is a clean and efficient renewable energy. Among its various utilization methods, solar photovoltaic power generation and solar thermal utilization are the main development directions of current solar energy utilization. The efficiency of solar photovoltaic power generation is relatively low, usually less than 15%, which means that most of the sunlight is reflected or converted into heat. The output power of solar silicon cells will decrease with the increase of their own temperature, and the power generation efficiency will decrease by about 0.3% for every 1℃ increase. Solar photovoltaic photothermal technology combines photovoltaic cells with solar heat collection technology, uses cooling medium in the heat collection assembly to take away the heat of solar photovoltaic panels and utilize it, improves the efficiency of photovoltaic power generation, and utilizes the heat energy of sunlight. The collected part of the light and heat has a low quality, lower than 50℃. How to efficiently utilize the light and heat resources for greenhouse insulation has become a problem to be solved.

[0004] CN104025947B discloses a self-circulating greenhouse, which uses rainwater as the heat transfer medium of photovoltaic and photothermal components, and realizes heat circulation and self-provision of electricity in the greenhouse through the heat preservation front wall and the underground heat preservation layer. CN114600678A discloses a photovoltaic and photothermal integrated greenhouse, which receives solar radiation at the top of the greenhouse through multiple vacuum heat collecting pipes, avoids continuous temperature rise in the greenhouse, and stores excess heat in water to dissipate heat at night to maintain the temperature in the greenhouse. CN209359161U discloses an energy-saving greenhouse constant temperature system, which communicates the inside of the greenhouse with the inside of the heat pump unit body to form a circulating air path, can meet the constant temperature demand of refrigeration and heating in the greenhouse, and can ensure the normal operation of the heat pump unit. CN106613531B provides a photovoltaic and photothermal integrated circulating system for a greenhouse, which can realize switching of seasonal operation modes and improve heat utilization efficiency, and uses a heat pump unit to realize self-provision of heat and electricity without additional auxiliary heating equipment.

[0005] The problems of the above photovoltaic and photothermal greenhouses are as follows:

[0006] (1) The starting point of photovoltaic and photothermal design is to reduce the temperature of photovoltaic panels to improve photovoltaic power generation efficiency, which is not designed around the heat storage and heat preservation of the greenhouse. The result is that photovoltaic power generation meets the self-provision of electricity for the greenhouse, but cannot meet the self-provision of heat for the heat preservation of the greenhouse, and new solar heat collecting technology suitable for the structural characteristics of the greenhouse needs to be added.

[0007] (2) The economic efficiency of using heat pump technology to use light and heat for heat preservation in the greenhouse is not high. The heat pump unit consumes high-quality electricity to improve low-quality light and heat for heat preservation in the greenhouse, which deviates from the principle of "using energy according to its quality", resulting in high energy consumption for heat preservation in the greenhouse and significant increase in investment cost of photovoltaic power generation.

[0008] (3) During the day when the sunlight is strong, the greenhouse does not need heat preservation or consumes less electricity and light and heat energy for heat preservation. Photovoltaic and photothermal are mainly used for heat preservation in the greenhouse at night. Photovoltaic power generation is difficult to store for driving the heat pump at night at low cost, and the collected light and heat are difficult to be used for heat preservation in the greenhouse at night. There is a lack of reasonable matching between photovoltaic electricity and light and heat energy to achieve efficient heat storage and heat preservation in the greenhouse.

[0009] (4) Air is mainly used as the medium, and the heat preservation of crops in the greenhouse is carried out by air convection. The result is that hot air flows upwards from the stems of the crops, and the hot air does not act on the roots of the crops which need heat preservation the most. The effect of heat preservation on crop growth is not good, and there is a lack of heat preservation and heat transfer methods suitable for the special characteristics of greenhouse planting. SUMMARY

[0010] The purpose of the present application is to overcome the existing technical defects, provide a photovoltaic light heat integrated heat storage and heat preservation system which improves photovoltaic power generation efficiency and heat utilization efficiency, the system takes the heat preservation of greenhouse as the design starting point, the heat generated by photovoltaic power generation is directly used as the heat source of the heat storage water tank, the electric load and investment cost of photovoltaic power generation are reduced; the heat storage water tank and the electric heating water tank are adopted, the sunlight photovoltaic light heat in the daytime is used for heat preservation at night; the phase change heat collecting plate is arranged on the north wall, the reasonable matching between photovoltaic electric energy and photothermal heat energy is realized by increasing the light heat, the efficient heat storage and heat preservation of the greenhouse are ensured, the efficient utilization of the space of the greenhouse is realized by utilizing the vertical wall space of the north wall, the heat collecting technology suitable for the structural characteristics of the greenhouse is realized; the drip irrigation device is used for crop root heat preservation, and the heat transfer efficiency and heat preservation effect are improved.

[0011] The present application is realized by the following technical solutions:

[0012] A greenhouse heat storage and heat preservation system based on photovoltaic light heat, the system comprises a heat storage device, a phase change heat collecting device, a drip irrigation device, a geothermal device, a photovoltaic light heat component and a roller blind machine;

[0013] The heat storage water tank in the heat storage device is connected to the photovoltaic light heat component in sequence through a photovoltaic regulating valve and a photovoltaic circulating pump, and then connected back to the heat storage water tank through a pipeline;

[0014] The phase change heat collecting plate in the phase change heat collecting device is an endothermic plate, an adhesive, a solid phase change layer, a fluid passage and a heat preservation layer in sequence; the heat storage water tank is connected to the inlet end of the fluid passage in sequence through a heat collecting regulating valve and a heat collecting circulating pump, and the outlet end of the fluid passage is connected back to the heat storage water tank through a pipeline;

[0015] The electric heating water tank in the geothermal device is connected to one end of the geothermal pipe in sequence through a geothermal circulating pump and a geothermal front valve, and the other end of the geothermal pipe is connected back to the electric heating water tank through a pipeline;

[0016] The drip irrigation water tank in the drip irrigation device is connected to the geothermal pipe in sequence through a drip irrigation circulating pump and a drip irrigation regulating valve, the drip irrigation water outlet of the geothermal pipe is connected with the drip irrigation water inlet, the pipeline section connected with the drip irrigation water inlet is provided with an electromagnetic cut-off valve and a drip irrigation port, and the end part of the pipeline is provided with a spray port;

[0017] A heat conducting plate 9 is arranged between the heat storage water tank and the electric heating water tank.

[0018] The photovoltaic light heat component is electrically connected with the electric heating water tank, the photovoltaic circulating pump, the heat collecting circulating pump, the geothermal circulating pump, the drip irrigation circulating pump, the roller blind machine, the illuminating lamp and the storage battery.

[0019] Aerogel heat preservation material is arranged on the outer layer of the heat storage water tank and the electric heating water tank.

[0020] A working method of a greenhouse heat storage and preservation system based on photovoltaic photothermal, comprising the following steps:

[0021] a. The photovoltaic photothermal assembly is connected with the heat storage water tank. The paraffin solution / oxidized graphene phase change fluid flows through the photovoltaic photothermal assembly to exchange heat, and the heat carried away is stored in the heat storage water tank;

[0022] b. The phase change heat collecting plate is connected with the heat storage water tank. The heat absorbing layer in the phase change heat collecting plate absorbs the heat of solar radiation, which is stored by the solid phase change layer;

[0023] When the paraffin solution / oxidized graphene phase change fluid in the heat storage water tank flows through the fluid channel, heat exchange is carried out, and the heat is carried to the heat storage water tank 2 for storage;

[0024] c. The heat storage water tank exchanges heat with the water in the electric heating water tank through the heat conducting plate, and the water in the electric heating water tank is preliminarily heated;

[0025] d. The electric heating water tank is connected with the geothermal pipe. The temperature control system in the electric heating water tank automatically heats the water preheated by the heat storage water tank to the required water temperature according to the temperature requirement in the greenhouse

[0026] e. The water in the electric heating water tank is sent to the geothermal pipe by the water pump, and the heat is transferred to the vegetation layer through the geothermal pipe;

[0027] f. The drip irrigation water tank, the geothermal pipe and the drip irrigation device are connected. The electromagnetic intercepting valve of the drip irrigation device is opened, the opening degree of the drip irrigation port is adjusted, and the water in the drip irrigation water tank is used for drip irrigation of the vegetation through the geothermal pipe and the drip irrigation device;

[0028] g. When the temperature in the greenhouse is too high, the spray port is opened to carry out direct evaporation cooling.

[0029] A working mode of a greenhouse heat storage and preservation system based on photovoltaic photothermal:

[0030] i) Daytime operation mode in fine weather:

[0031] Open the photovoltaic regulating valve and the heat collecting regulating valve, close the geothermal front valve, the geothermal rear valve and the drip irrigation regulating valve, the 20-25℃ phase change fluid in the photovoltaic photothermal assembly and the phase change heat collecting plate is heated to 35-40℃ after being irradiated by sunlight, and the heated phase change fluid is transported to the heat storage water tank for storage by the photovoltaic circulating pump and the heat collecting circulating pump;

[0032] ii) Night operation mode with low temperature requirement:

[0033] Open the heat collecting regulating valve and the heat collecting water pump, close the photovoltaic regulating valve, the geothermal front valve, the geothermal rear valve and the drip irrigation regulating valve, the 30-35℃ low temperature phase change fluid in the heat storage water tank transfers heat to the phase change heat collecting plate, and the phase change heat collecting plate transfers heat to the greenhouse through convective heat exchange;

[0034] iii) Operation mode when the air temperature is low and the light is insufficient:

[0035] The geothermal front valve and the geothermal rear valve are opened, the photovoltaic regulating valve, the heat collection regulating valve and the drip irrigation regulating valve are closed, the water in the electric heating water tank absorbs the heat in the heat storage water tank to become low-temperature hot water of 30℃±5℃, which is further treated to the set temperature by electric heating, and the heated water is transported to the geothermal pipe by the geothermal circulating valve, and the heat is dissipated to the vegetation layer through the geothermal pipe;

[0036] iv) Night operation mode when the air temperature is low and the light is sufficient during the day:

[0037] The heat collection regulating valve, the geothermal front valve and the geothermal rear valve are opened, and the photovoltaic regulating valve and the drip irrigation regulating valve are closed, and the heat in the heat storage water tank and the electric heating water tank is transmitted to the greenhouse through the phase change heat collection plate and the geothermal pipe respectively;

[0038] v) Drip irrigation mode:

[0039] The drip irrigation regulating valve is opened, the geothermal front valve and the geothermal rear valve are closed, the electromagnetic intercepting valve of the drip irrigation device is opened, the opening degree of the drip irrigation port is adjusted, and the water in the drip irrigation water tank is used for drip irrigation of the vegetation through the geothermal pipe and the drip irrigation device; when the temperature in the greenhouse is too high, the spray port of the drip irrigation device is rotated to open, and direct evaporation cooling is performed.

[0040] Further, the geothermal pipe plays the roles of heat transfer and irrigation. When irrigation is performed, the valve connected to the electric heating water tank is closed, the valve connected to the drip irrigation water tank is opened, and the electromagnetic valve of the drip irrigation device is opened, and the water pump sends the water in the drip irrigation water tank to the drip irrigation device for irrigation; when heat transfer is performed, the valve connected to the drip irrigation water tank is closed, the valve connected to the electric heating water tank is opened, and the water pump sends the heated water to the geothermal pipe for heat exchange.

[0041] The phase change heat collection plate is connected to the heat storage water tank through a water pump, collects the heat of solar radiation, heats the fluid medium in the heat storage water tank, and when it is night or the light is insufficient during the day, the phase change heat collection plate can also act as a heat dissipation plate to transfer the heat in the heat storage water tank to the greenhouse through the way of convective heat transfer.

[0042] Further, the photovoltaic light heat assembly is placed at the back of the greenhouse, does not hinder the operation of the greenhouse, does not have shading effect on the vegetation in the greenhouse, and is convenient for disassembly and maintenance; the back of the photovoltaic panel is a grid type fluid channel made of blow molding aluminum plate process, which improves the heat transfer efficiency;

[0043] Further, the photovoltaic light heat assembly, the phase change heat collection plate and the fluid medium in the heat storage water tank are paraffin solution / oxidized graphene composite phase change materials, which have better heat conduction performance and higher heat storage density than water;

[0044] Further, the heat storage water tank and the electric heating water tank are externally provided with aerogel thermal insulation materials, and the electric heating water tank is internally provided with a temperature control system, which can automatically heat to the required water temperature according to the temperature requirement in the shed.

[0045] Further, the drip irrigation device is connected with the geothermal pipe through a rubber head, and an electromagnetic valve for controlling opening and closing is arranged behind the interface, the drip irrigation rod is connected with the water hose, the drip irrigation rod can be placed according to the position of the vegetation, the conical head at the bottom is inserted into the soil to play a fixing role, the drip irrigation rod is provided with adjustable drip irrigation openings, and the top of the drip irrigation rod is provided with a rotating opening and closing spray nozzle, when the temperature in the shed is too high, the temperature is reduced through the direct evaporation cooling mode.

[0046] The beneficial effects of the present application are:

[0047] (1) Without external power supply or fuel consumption, solar photovoltaic power generation and photothermal heat are used to realize the heat preservation of the greenhouse, and the cost of the heat preservation of the greenhouse is greatly reduced.

[0048] (2) According to the requirements of the greenhouse heat preservation, the photovoltaic electric energy and the photothermal heat energy are reasonably matched, the photothermal heat of the photovoltaic power generation and the low-quality photothermal heat of the phase change heat collecting plate are used as the main heat source of the greenhouse heat preservation, the collected photothermal heat does not need to consume high-quality electric energy but is directly stored in the heat storage water tank for the heat preservation of the greenhouse, the photovoltaic power generation is used to heat the electric heating water tank for assisting the heat preservation of the greenhouse, and the photothermal heat and the photovoltaic energy are stored in the heat storage water tank and the electric heating water tank respectively, so that the solar energy in the daytime is used for the heat preservation of the greenhouse at night at low cost.

[0049] (3) According to the structure characteristics of the greenhouse that the vertical wall space of the north wall is large and the drip irrigation device directly contacts the root part of crops, a photothermal heat preservation technology suitable for the greenhouse is developed, the phase change heat collecting plate is arranged on the vertical wall of the north wall, the sunlight can be fully utilized to improve the photothermal heat collection efficiency, and the planting space of crops in the greenhouse is saved, the existing drip irrigation device is used as the geothermal pipe for the heat preservation of the greenhouse, and heat is directly transmitted to the root part of crops to improve the heat preservation effect and the heat transfer rate. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 It is a schematic view of a greenhouse heat storage and heat preservation system based on photovoltaic photothermal.

[0051] Figure 2 It is a structure schematic view of a phase change heat collecting plate.

[0052] Figure 3 It is a structure schematic view of the drip irrigation device.

[0053] The figure mark is: 1, photovoltaic photothermal assembly, 2, heat storage water tank, 201, heat conduction plate, 3, electric heating water tank, 4, drip irrigation water tank, 5, phase change heat collecting plate, 501, heat absorbing plate, 502, adhesive, 503, solid phase change layer, 504, fluid channel, 505, thermal insulation layer, 6, geothermal pipe, 601, drip irrigation outlet, 701, photovoltaic circulating pump, 702, heat collecting circulating pump, 703, geothermal circulating pump, 704, drip irrigation circulating pump, 801, photovoltaic regulating valve, 802, heat collecting regulating valve, 803, geothermal front valve, 804, drip irrigation regulating valve, 805, geothermal rear valve, 901, drip irrigation inlet, 902, electromagnetic cut-off valve, 903, drip irrigation outlet, 904, spray outlet, 10, roller shutter machine. DETAILED DESCRIPTION

[0054] The present application will be further illustrated below in conjunction with the drawings and specific embodiments, and it should be understood that the following specific embodiments are only used to illustrate the present application and not to limit the scope of the present application. The examples described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0055] As Figure 1 shown, the present application proposes a greenhouse heat storage and insulation system based on photovoltaic photothermal, which includes photovoltaic photothermal assembly 1, heat storage water tank 2, electric heating water tank 3, drip irrigation water tank 4, phase change heat collecting plate 5, geothermal pipe 6, circulating water pump 7, regulating valve 8, drip irrigation device 9, and roller shutter machine 10.

[0056] Specifically, the photovoltaic photothermal assembly 1 is connected with the heat storage water tank 2, wherein the paraffin solution / graphene oxide phase change fluid takes away the heat from the back of the photovoltaic panel, reduces the temperature of the photovoltaic panel, improves the power generation efficiency of the photovoltaic panel, and stores the heat in the heat storage water tank 2.

[0057] The phase change heat collecting plate 5 is connected with the heat storage water tank 2, the heat absorbing layer 501 in the phase change heat collecting plate 2 absorbs the heat of solar radiation, which is stored by the solid phase change layer 502, and when the paraffin solution / graphene oxide phase change fluid flows through the fluid channel 504, the heat is taken to the heat storage water tank 2 for storage. The heat storage water tank 2 stores the heat from the photovoltaic photothermal assembly 1 and the phase change heat collecting plate 5, and the fluid medium in it exchanges heat with the water in the electric heating water tank 3 through the heat conduction plate 201, preliminarily heats the water in the electric heating water tank 3, and the heat storage water tank and the electric heating water tank are externally provided with aerogel thermal insulation material.

[0058] The electric heating water tank 3 is connected with the geothermal pipe 6, and the electric heating water tank 3 has a temperature control system. According to the temperature requirement in the shed, the water preheated by the heat storage water tank 2 is automatically heated to the required water temperature, and the required electric energy is from the photovoltaic panel. The treated water is transported to the geothermal pipe 6 by the water pump, and the heat is dissipated to the vegetation layer through the geothermal pipe 6. The geothermal pipe 6 is also connected with the drip irrigation water tank 4 and the drip irrigation device 9 to form a drip irrigation system. At this time, the electromagnetic intercepting valve 902 of the drip irrigation device is opened, the drip irrigation opening 903 is adjusted to the appropriate opening degree, the water from the drip irrigation water tank 4 is dripped to the vegetation through the heat pipe and the drip irrigation device, and when the temperature in the shed is too high, the spray opening 904 of the drip irrigation device is opened to directly evaporate and cool.

[0059] The system has a stable and energy-saving operation mode, which can effectively maintain the constant temperature in the shed according to the change of external temperature. The shed has multiple operation modes.

[0060] i) Daytime operation mode in fine weather:

[0061] The photovoltaic regulation valve 801 and the heat collection regulation valve 802 are opened, and the geothermal front valve 803, the geothermal rear valve 805 and the drip irrigation regulation valve 804 are closed. The 20-25℃ phase change fluid in the photovoltaic light heat assembly 1 and the phase change heat collection plate 5 is heated to 35-40℃ after being irradiated by sunlight, and the heated phase change fluid is transported to the heat storage water tank 2 by the photovoltaic circulating pump 701 and the heat collection circulating pump 702.

[0062] ii) Night operation mode with low temperature requirement:

[0063] The heat collection regulation valve 802 and the heat collection water pump 702 are opened, and the photovoltaic regulation valve 801, the geothermal front valve 803, the geothermal rear valve 805 and the drip irrigation regulation valve 804 are closed. The 30-35℃ low-temperature phase change fluid in the heat storage water tank 2 transfers heat to the phase change heat collection plate 5, and the phase change heat collection plate 5 transfers heat to the shed through convection heat exchange.

[0064] iii) Operation mode in low temperature and insufficient light:

[0065] The geothermal front valve 803 and the geothermal rear valve 805 are opened, and the photovoltaic regulation valve 801, the heat collection regulation valve 802 and the drip irrigation regulation valve 804 are closed. The water in the electric heating water tank 3 absorbs the heat in the heat storage water tank 2 to become 30℃±5℃ low-temperature hot water, which is further heated to the set temperature by electric heating. The heated water is transported to the geothermal pipe 6 by the geothermal circulating valve 703, and the heat is dissipated to the vegetation layer through the geothermal pipe 6.

[0066] iv) Night operation mode in low temperature and sufficient daytime light:

[0067] The heat collecting regulating valve 802, the geothermal front valve 803 and the geothermal rear valve 805 are opened, and the photovoltaic regulating valve 801 and the drip irrigation regulating valve 804 are closed, so that the heat in the heat storage water tank 2 and the electric heating water tank 3 is respectively transmitted into the greenhouse through the phase change heat collecting plate 5 and the geothermal pipe 6;

[0068] v) drip irrigation mode:

[0069] The drip irrigation regulating valve 804 is opened, the geothermal front valve 803 and the geothermal rear valve 805 are closed, the electromagnetic intercepting valve 902 of the drip irrigation device is opened, the opening degree of the drip irrigation port 903 is adjusted, and the water in the drip irrigation water tank 4 is sequentially transmitted into the geothermal pipe 6 and the drip irrigation device to drip irrigate the vegetation; when the temperature in the greenhouse is too high, the spray port 904 of the drip irrigation device is rotated to open, and direct evaporation cooling is performed.

[0070] Under the condition that the temperature outside the greenhouse is low, the roller shutter machine 10 will lower the heat preservation quilt to cover the outside of the greenhouse, so as to reduce the heat loss in the greenhouse.

[0071] The electric energy generated by the photovoltaic panel is used for the electric heating water tank, the water pump, the lighting and the roller shutter machine, and the excess electric energy is stored in the storage battery.

[0072] In the embodiment, the operation and control system of all circulating pumps and all regulating valves, the electric heating water tank 3 and the electromagnetic intercepting valve 902 is a full-automatic control system, which can automatically adjust the system operation according to various monitoring signal feedbacks, and the pipeline is provided with an anti-freezing device which will be automatically started in the cold season or at night when the temperature is low.

[0073] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit the present application. Although the present application is described in detail with reference to the foregoing embodiments, the ordinary skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and the modification or replacement does not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the present application.

[0074] The technical means disclosed in the technical solutions of the present application is not limited to the technical means disclosed in the above technical means, but also includes the technical solutions composed of any combination of the above technical features.

Claims

1. A working method of a greenhouse heat storage and preservation system based on photovoltaic photothermal, characterized in that: the system comprises a heat storage device, a phase change heat collection device, a drip irrigation device, a geothermal device, a photovoltaic photothermal component (1) and a roller shutter machine (10); the heat storage device is connected to the photovoltaic photothermal component (1) through a photovoltaic regulating valve (801) and a photovoltaic circulating pump (701) in sequence, and then connected back to the heat storage water tank (2) through a pipeline; the phase change heat collection device is composed of a heat absorption plate (501), an adhesive (502), a solid phase change layer (503), a fluid channel (504) and an insulation layer (505) in sequence; the heat storage water tank (2) is connected to the inlet end of the fluid channel (504) through a heat collection regulating valve (802) and a heat collection circulating pump (702) in sequence, and the outlet end of the fluid channel (504) is connected back to the heat storage water tank (2) through a pipeline; the geothermal device is connected to one end of the geothermal pipe (6) through a geothermal circulating pump (703) and a geothermal front valve (803), and the other end of the geothermal pipe (6) is connected back to the electric heating water tank (3) through a pipeline; the drip irrigation device is connected to the geothermal pipe (6) through a drip irrigation circulating pump (704) and a drip irrigation regulating valve (804), the drip irrigation outlet (601) of the geothermal pipe (6) is connected to the drip irrigation inlet (901), and the pipeline connected to the drip irrigation inlet (901) is provided with an electromagnetic cut-off valve (902) and a drip irrigation port (903), and the end of the pipeline is provided with a spray port (904); a heat conduction plate (201) is arranged between the heat storage water tank (2) and the electric heating water tank (3); the working method comprises the following steps: a, the photovoltaic photothermal component (1) is connected to the heat storage water tank (2), the paraffin solution / oxidized graphene phase change fluid flows through the photovoltaic photothermal component (1) to exchange heat, and the heat carried away is stored in the heat storage water tank (2); b, the phase change heat collection plate (5) is connected to the heat storage water tank (2), the heat absorption plate (501) in the phase change heat collection plate (5) absorbs the heat of solar radiation, and the heat is stored by the solid phase change layer (503); when the paraffin solution / oxidized graphene phase change fluid in the heat storage water tank (2) flows through the fluid channel (504), heat exchange is performed, and the heat is carried away to be stored in the heat storage water tank (2); c, the heat storage water tank (2) exchanges heat with the water in the electric heating water tank (3) through the heat conduction plate (201), and the water in the electric heating water tank (3) is preliminarily heated; d, the electric heating water tank (3) is connected to the geothermal pipe (6), and the temperature control system in the electric heating water tank (3) automatically heats the water preheated by the heat storage water tank (2) to the required water temperature according to the temperature requirement in the greenhouse; e, the water in the electric heating water tank (3) is delivered to the geothermal pipe (6) through a water pump, and the heat is transmitted to the vegetation layer through the geothermal pipe (6); f, the drip irrigation water tank (4), the geothermal pipe (6) and the drip irrigation device are connected, the electromagnetic cut-off valve (902) of the drip irrigation device is opened, the opening degree of the drip irrigation port (903) is adjusted, and the water in the drip irrigation water tank (4) is used for drip irrigation of the vegetation through the geothermal pipe (6) and the drip irrigation device. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ g. When the temperature inside the greenhouse is too high, rotate and open the spray nozzle (904) to directly evaporate and cool down.

2. The working method of the photovoltaic photo-thermal based greenhouse heat storage and preservation system according to claim 1, characterized in that: The photovoltaic thermal module (1) is electrically connected to the electric heating water tank (3), photovoltaic circulation pump (701), heat collection circulation pump (702), geothermal circulation pump (703), drip irrigation circulation pump (704), roller shutter machine (10), lighting lamp, and storage battery.

3. The working method of the photovoltaic photo-thermal based greenhouse heat storage and preservation system according to claim 2, characterized in that: The outer layer of the hot water storage tank (2) and the electric heating water tank (3) is provided with aerogel insulation material.

4. A working mode of a greenhouse heat storage and insulation system based on photovoltaic thermal energy, characterized in that: The system includes a heat storage device, a phase change heat collection device, a drip irrigation device, a geothermal device, a photovoltaic thermal module (1), and a rolling shutter machine (10). The hot water storage tank (2) in the heat storage device is connected to the photovoltaic thermal module (1) in sequence through the photovoltaic regulating valve (801) and the photovoltaic circulation pump (701), and then connected back to the hot water storage tank (2) through the pipeline. The phase change heat collection device consists of a heat absorption plate (501), an adhesive (502), a solid phase change layer (503), a fluid channel (504), and an insulation layer (505) in sequence. The hot water storage tank (2) is connected to the inlet end of the fluid channel (504) in sequence through a heat collection regulating valve (802) and a heat collection circulation pump (702). The outlet end of the fluid channel (504) is connected back to the hot water storage tank (2) through a pipeline. In the geothermal device, the electric heating water tank (3) is connected to one end of the geothermal pipe (6) via the geothermal circulation pump (703) and the geothermal front valve (803), and the other end of the geothermal pipe (6) is connected back to the electric heating water tank (3) via the geothermal back valve (805). In the drip irrigation device, the drip irrigation tank (4) is connected to the geothermal pipe (6) in sequence via the drip irrigation circulation pump (704) and the drip irrigation regulating valve (804). The drip irrigation outlet (601) of the geothermal pipe (6) is connected to the drip irrigation inlet (901). An electromagnetic shut-off valve (902) and a drip irrigation port (903) are installed on the pipeline connected to the drip irrigation inlet (901). A spray nozzle (904) is installed at the end of the pipeline. A heat-conducting plate (201) is provided between the hot water storage tank (2) and the electric heating water tank (3); i) Daytime operation mode in sunny weather: Open the photovoltaic regulating valve (801) and the heat collector regulating valve (802), and close the geothermal front valve (803), the geothermal back valve (805) and the drip irrigation regulating valve (804). The phase change fluid in the photovoltaic thermal module (1) and the phase change heat collector plate (5) at 20-25°C is heated to 35-40°C after being irradiated by sunlight. The heated phase change fluid is then transported to the hot water storage tank (2) for storage through the photovoltaic circulation pump (701) and the heat collector circulation pump (702). ii) Nighttime operation mode with low temperature requirements: Open the heat collection regulating valve (802) and the heat collection circulation pump (702), and close the photovoltaic regulating valve (801), the geothermal front valve (803), the geothermal back valve (805) and the drip irrigation regulating valve (804). The 30-35℃ low temperature phase change fluid in the hot water storage tank (2) transfers heat to the phase change heat collection plate (5), and the phase change heat collection plate (5) transfers heat to the greenhouse through convection heat exchange. iii) Low temperature and insufficient light operation mode: Open the geothermal front valve (803) and the geothermal rear valve (805), close the photovoltaic regulating valve (801), the heat collection regulating valve (802) and the drip irrigation regulating valve (804), the water in the electric heating water tank (3) absorbs the heat in the heat storage water tank (2) to become low temperature hot water of 30℃±5℃, which is further processed to the set temperature by electric heating, and the heated water is transported to the geothermal pipe (6) by the geothermal circulating valve (703), and the heat is dissipated to the vegetation layer through the geothermal pipe (6); iv) Low temperature and sufficient light during the day and night operation mode: Open the heat collection regulating valve (802), the geothermal front valve (803) and the geothermal rear valve (805), close the photovoltaic regulating valve (801) and the drip irrigation regulating valve (804), and the heat in the heat storage water tank (2) and the electric heating water tank (3) is transmitted to the greenhouse through the phase change heat collection plate (5) and the geothermal pipe (6) respectively; v) Drip irrigation mode: Open the drip irrigation regulating valve (804), close the geothermal front valve (803) and the geothermal rear valve (805), open the electromagnetic shutoff valve (902) of the drip irrigation device, adjust the opening of the drip irrigation port (903), and the water in the drip irrigation water tank (4) is used for drip irrigation of the vegetation through the geothermal pipe (6) and the drip irrigation device; when the temperature in the greenhouse is too high, rotate to open the spray port (904) of the drip irrigation device to perform direct evaporative cooling.

5. The working mode of the photovoltaic photo-thermal based greenhouse heat storage and preservation system according to claim 4, characterized in that: The photovoltaic light heat assembly (1) is electrically connected with the electric heating water tank (3), the photovoltaic circulating pump (701), the heat collection circulating pump (702), the geothermal circulating pump (703), the drip irrigation circulating pump (704), the roller shutter machine (10), the lighting lamp and the storage battery.

6. The working mode of the photovoltaic photo-thermal based greenhouse heat storage and preservation system according to claim 5, characterized in that: The outer layer of the heat storage water tank (2) and the electric heating water tank (3) is provided with aerogel thermal insulation material.

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