Photovoltaic heat recycling system

Abstract

The invention discloses a photovoltaic heat recycling system which is mainly composed of a photovoltaic array, a heat pump unit and a two-stage heat exchange unit. The photovoltaic array comprises a plurality of photovoltaic cell panels and is responsible for generating electric energy. The heat pump unit is driven by electric energy generated by the photovoltaic array, can absorb heat from the environment, and supplies heat to user sides with different temperature requirement levels. The two-stage heat exchange unit is provided with two heat exchangers with different temperature grades, waste heat generated by the photovoltaic cell panel can be absorbed and utilized, meanwhile, the waste heat generated by the user sides with different temperature requirement grades is recycled in a stepped mode, and the waste heat is supplied to the user side with the temperature requirement of the next stage. According to the system, efficient utilization of heat is achieved, waste heat and waste heat are fully recycled while environment heat is obtained to meet the user requirement, the comprehensive utilization rate of energy is increased, and a new solution is provided for efficient utilization of energy.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic heat recovery. More specifically, the present invention relates to a photovoltaic heat recovery and reuse system. Background Art

[0002] In this context, solar energy, as a clean and renewable energy source, has become a key focus in the energy field. Photovoltaic technology converts solar energy into electrical energy through photovoltaic cells and has developed rapidly with the continuous increase in installed capacity. However, the energy conversion efficiency of photovoltaic cells is limited, and the common conversion efficiency is only 15% - 25%. Most of the solar energy is wasted in the form of heat, resulting in an increase in the temperature of the battery, which not only reduces the power generation efficiency but also affects the service life. To improve the comprehensive utilization efficiency of solar energy, photovoltaic heat recovery and reuse systems have emerged. Early systems mostly used air or liquid cooling to recover waste heat. Although air cooling has a simple structure and low cost, due to the small specific heat capacity of air and weak heat transfer ability, the recovered heat is limited and the application range is narrow; liquid cooling has high heat transfer efficiency, but the system is complex, requiring equipment such as circulation pumps, consuming electricity and having the risk of liquid leakage, and the maintenance cost is high.

[0003] Later, advanced systems introduced heat pump technology, using the electrical energy of the photovoltaic array to drive the heat pump to absorb heat from the environment and raise the temperature for different user terminals. However, the existing photovoltaic heat recovery and reuse systems still have key deficiencies.

[0004] In industrial production, construction and other fields, there are various temperature demand scenarios, such as high-temperature industrial processes, medium-temperature building heating and hot water supply, low-temperature ventilation and precooling, etc. However, the existing systems lack an effective mechanism for cascaded recovery and utilization of waste heat. In industrial production, high-temperature waste heat is often not reasonably recovered and is directly discharged, causing both energy loss and environmental heat pollution. For example, the high-temperature waste heat generated in some chemical production processes is discharged into the environment without being fully utilized, wasting a large amount of energy. In the building field, different heat-using links have different temperature requirements, and the existing systems cannot well cascade the utilization of waste heat to meet the requirements of each link, resulting in low energy utilization efficiency. For example, in the invention patent with the publication number CN115307204A, it discloses a solar energy coupling system combined with the waste heat recovery of bathroom wastewater and waste gas, which is mainly designed for the waste heat recovery of bathroom wastewater and waste gas and functions such as heating, power supply, and hot water supply. Through the coupled energy supply of a waste heat recovery unit, a solar photovoltaic system, and an air source heat pump unit, a certain degree of comprehensive energy utilization is achieved. However, the application scenarios and focuses of this system are different from those of the photovoltaic heat recovery and reuse system, and it does not focus on solving the problem of cascaded recovery and utilization of waste heat widely existing in industrial production and the building field.

[0005] Therefore, how to solve the lack of a cascaded recovery and utilization mechanism for waste heat in the existing photovoltaic heat recovery and reuse system to improve the comprehensive utilization efficiency of solar energy has become the biggest technical problem to be solved urgently.

[0006] In addition, there is still room for optimization in the maximum power point tracking technology of the photovoltaic array. Its output power is affected by factors such as light intensity and temperature, and the maximum power point is prone to drift. Existing tracking methods cannot track quickly and accurately in some cases, reducing the power generation efficiency. For example, when the light intensity changes rapidly, traditional methods will have a tracking lag, affecting power generation.

[0007] In terms of heat exchangers, existing devices cannot meet the system requirements in terms of heat transfer efficiency, structural compactness, and reliability. They are prone to fouling and corrosion during long-term operation, resulting in a decrease in heat transfer efficiency and affecting the system performance and lifespan. On the basis of solving the above technical problems, while improving the deficiencies in the maximum power point tracking technology of the photovoltaic array and the poor performance of the heat exchanger, in order to enhance the stability and reliability of the photovoltaic system, it is expected that the photovoltaic heat recovery and reuse system will play a more important role in the energy field. Summary of the Invention

[0008] An object of the present invention is to solve at least the above problems and provide at least the advantages described hereinafter.

[0009] Another object of the present invention is to provide a photovoltaic heat recovery and reuse system, which realizes the effective recovery and cascade utilization of waste heat and surplus heat by reasonably configuring a photovoltaic array, a heat pump unit, and a two-stage heat exchanger unit.

[0010] To achieve these objects and other advantages of the present invention, there is provided a photovoltaic heat recovery and reuse system, comprising: A photovoltaic array, which includes several photovoltaic panels; A heat pump unit, which is driven by the electric energy generated by the photovoltaic array and is used to absorb heat from the environment and supply it to user terminals with different temperature demand levels; A two-stage heat exchanger unit, which includes two heat exchangers with different temperature levels, is used to absorb and utilize the waste heat generated by the photovoltaic panels and perform cascade recovery on the surplus heat generated by user terminals with different temperature demand levels and supply it to user terminals with the next lower temperature demand level; Wherein, the heat pump unit absorbs heat from the environment and transports it to the user terminal with the first-level temperature demand through the first-stage heat exchanger. The first-stage heat exchanger receives the waste heat generated by the photovoltaic panels and the surplus heat of the user terminal with the first-level temperature demand, and transports it to the user terminal with the next lower temperature demand through the secondary heat exchanger. The secondary heat exchanger receives the surplus heat discharged from the first-stage heat exchanger.

[0011] Preferably, a plurality of panels are arranged in a matrix, and a spiral heat conduction channel is provided on the back of each photovoltaic panel. A heat conduction medium flows through the heat conduction channel, and the heat conduction medium absorbs the waste heat generated by the photovoltaic panel and transfers the heat to the first-stage heat exchanger.

[0012] Preferably, the photovoltaic array is composed of n panels connected in series and m groups of series-connected panels connected in parallel; The output terminal of the photovoltaic array is connected to a DC busbar box, which aggregates the DC outputs of m groups of series-connected panels. The DC power output from the DC busbar box is connected to an inverter with a maximum power point tracking function; Among them, the method for realizing the maximum power point tracking function is as follows: S1. Divide the operating voltage range into multiple intervals, including a low voltage area, a medium voltage area, and a high voltage area, according to the open circuit voltage, which is the theoretical upper limit value of the output voltage of the photovoltaic array; S2. Set different perturbation step sizes in each interval, where the perturbation step size in the low voltage area is greater than that in the medium voltage area, and the perturbation step size in the medium voltage area is greater than that in the high voltage area; S3. Monitor the output voltage and current of the photovoltaic array in real time and calculate the current power; S4. Determine the interval to which the current voltage value belongs and select the corresponding perturbation step size; S5. Apply a voltage perturbation to adjust the operating point of the photovoltaic array and compare the power change before and after the perturbation; if the power increases, maintain the perturbation direction; if the power decreases, reverse the perturbation direction; S6. Repeat the above steps until the photovoltaic array operates at the maximum power point.

[0013] Preferably, the multiple intervals into which the operating voltage range is divided according to the open circuit voltage, which is the theoretical upper limit value of the output voltage of the photovoltaic array, are as follows: Low voltage area: 0 to 50% of the open circuit voltage; Medium voltage area: 50% to 80% of the open circuit voltage; and, High voltage area: 80% to 100% of the open circuit voltage.

[0014] Preferably, setting different perturbation step sizes in each interval includes: The step size in the low voltage area is 2.0V; The step size in the medium voltage area is 1.0V; The step size in the high voltage area is 0.5V.

[0015] Preferably, the steps of applying a voltage perturbation in step S5 to adjust the operating point of the photovoltaic array and comparing the power change before and after the perturbation include: S51. Increase or decrease a perturbation step size based on the current voltage to obtain a new voltage value; S52. Adjust the operating point of the photovoltaic array to the new voltage value; S53. Measure the new power value and compare it with the power value before the perturbation.

[0016] Preferably, the diversion channels are bonded to the back of the photovoltaic panel by thermally conductive silica gel with a bonding thickness of 0.5 mm and a coverage rate of ≥95%. A flow channel outlet joint is provided at the end of each thermally conductive flow channel and is connected to the stainless steel corrugated hose by threading; each stainless steel corrugated hose is aggregated into a stainless steel header through a multi-pass header interface, and the header is connected to the inlet of the first-stage heat exchanger through a flange.

[0017] Preferably, both the first-stage heat exchanger and the sub-first-stage heat exchanger are shell-and-tube heat exchangers, each including a shell, two independent tube passes, and a shell pass; The outlet of the thermally conductive flow channel is connected to the inlet of the first group of tube passes of the first-stage heat exchanger. After the thermally conductive medium that has completed heat exchange flows out from the outlet of the first group of tube passes, it enters the first group of independent tube passes of the sub-first-stage heat exchanger, passes through a Y-shaped shunt tube, and is finally redistributed to the inlets of the thermally conductive flow channels of each photovoltaic panel to achieve circulation; The outlet of the condenser of the heat pump is connected to the inlet of the second tube pass of the first-stage heat exchanger. The refrigerant that has completed heat exchange flows out from the outlet of the second tube pass of the first-stage heat exchanger, passes through an electronic expansion valve, and returns to the inlet of the evaporator of the heat pump to achieve circulation; Connect the outlet end of the shell pass of the first-stage heat exchanger to the inlet of the liquid of the first-stage temperature-demand user end. The outlet of the first-stage temperature-demand user end is first connected to the inlet of the second group of tube passes of the sub-first-stage heat exchanger, and then passes through the outlet of the second group of tube passes of the sub-first-stage heat exchanger and is connected to the inlet of the liquid of the shell pass of the sub-first-stage heat exchanger; Connect the outlet end of the shell pass of the sub-first-stage heat exchanger to the inlet of the liquid of the second-stage temperature-demand user end, and connect the outlet of the second-stage temperature-demand user end to the inlet end of the shell pass of the first-stage heat exchanger to achieve circulation.

[0018] Preferably, the photovoltaic heat recovery and reuse system further includes a heat storage and energy storage mechanism, which is used to store the excess heat of the multi-stage heat exchange unit group and provide heat during peak heat demand or when the heat pump unit group has insufficient heat supply. The present invention has at least the following beneficial effects: First, the photovoltaic heat recovery and reuse system of the present invention is provided with a two-stage heat exchange unit group. Through two heat exchangers with different temperature levels, it can effectively absorb and cascade recover the waste heat generated by the photovoltaic panels and the waste heat generated by user ends with different temperature demand levels. First, the first-stage heat exchanger receives the waste heat of the photovoltaic panels and the waste heat of the first-stage temperature-demand user end, and then is transported to the sub-first-stage temperature-demand user end through the sub-first-stage heat exchanger, realizing the hierarchical utilization of waste heat; this method can make full use of thermal energy at different temperature levels to meet the needs of different user ends. Compared with the existing system lacking an effective waste heat cascade recovery and utilization mechanism, it greatly improves the comprehensive utilization efficiency of energy and reduces energy waste; Second, the photovoltaic array of the present invention is composed of individual solar panels connected in series, and groups of series-connected solar panels are then connected in parallel, and are connected through a DC busbar box and an inverter with the maximum power point tracking (MPPT) function; among them, the MPPT function implementation method divides the operating voltage range into low, medium, and high voltage regions according to the theoretical upper limit value, the open-circuit voltage, of the output voltage of the photovoltaic array, and different perturbation step sizes are set in different intervals (the step size in the low voltage region is 2.0V, the step size in the medium voltage region is 1.0V, and the step size in the high voltage region is 0.5V); this optimized MPPT method can track the maximum power point of the photovoltaic array more quickly and accurately, monitor the output voltage and current in real time and adjust the operating point. Compared with the traditional maximum power point tracking method, it can effectively avoid the problem of tracking lag when factors such as light intensity change, significantly improve the power generation efficiency of the photovoltaic array, and increase the electrical energy output of the system; Third, a heat storage and energy storage mechanism is provided in the photovoltaic thermal recovery and reuse system of the present invention, and this mechanism can store the excess heat recovered by the multi-stage heat exchange unit; when there is a peak in heat demand or the heat pump unit fails to supply enough heat, the heat storage and energy storage mechanism can provide heat in a timely manner to ensure that the system stably supplies heat to the user side; this setting enhances the stability and reliability of the system, effectively solves the possible instability problem in heat supply of the existing system, guarantees the heat demand of the user side, and improves the adaptability and practicality of the system; Fourth, both the first-stage heat exchanger and the next-stage heat exchanger in the present invention adopt shell-and-tube heat exchangers, and their internal structures and connection methods are carefully designed; a reasonable circulation connection is formed among the heat conduction flow channel, the heat exchanger, the heat pump unit, and the user side. For example, the outlet of the heat conduction flow channel is connected to the inlet of the first set of tube passes of the first-stage heat exchanger, and after heat exchange, it enters the next-stage heat exchanger in sequence, etc., to realize the circulation of the heat conduction medium; the outlet of the condenser of the heat pump is connected to the inlet of the second tube pass of the first-stage heat exchanger, and the refrigerant also realizes circulation; this design not only improves the heat exchange efficiency, but also the connections between components are tight and the circulation is orderly. Compared with the existing heat exchangers that are prone to fouling, corrosion, etc., resulting in a decrease in heat transfer efficiency, the heat exchanger structure and circulation design of the present invention are more reliable, can effectively ensure the long-term stable operation of the system, extend the service life of the system, and reduce the maintenance cost; Fifth, the spiral heat conduction channel arranged on the back of each photovoltaic panel of the present invention is bonded to the back of the panel by thermal conductive silicone with a bonding thickness of 0.5 mm and a coverage rate of not less than 95%, and a channel outlet joint is arranged at the end of each heat conduction channel, which is threadedly connected to the stainless steel corrugated hose, and each hose is collected to the stainless steel header through a multi-way header interface, and then connected to the inlet of the first-stage heat exchanger through a flange; this precise structural design and connection method ensures that the heat conduction medium can efficiently and stably absorb the waste heat generated by the photovoltaic panel, and accurately transfer the heat to the first-stage heat exchanger, reducing the loss in the heat transmission process, improving the efficiency and stability of waste heat recovery, and further enhancing the ability of the entire system to recycle the waste heat of the photovoltaic panel.

[0019] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of a photovoltaic heat recovery and reuse system in a technical solution of the present invention; Figure 2 This is a structural schematic diagram of another technical solution of the present invention to the photovoltaic heat recovery and reuse system; Among them, 1. Photovoltaic panels; 2. First-level heat exchanger; 3. First-level temperature demand user end; 4. Heat pump unit; 5. Second-level heat exchanger; 6. Second-level temperature demand user end; 7. Thermal energy storage mechanism. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0022] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0023] like Figure 1 , 2 As shown, the present invention provides a photovoltaic heat recovery and reuse system, comprising: A photovoltaic array, comprising a plurality of photovoltaic panels 1; A heat pump unit 4, which is driven by the electric energy generated by the photovoltaic array, is used to absorb heat from the environment and supply it to users with different temperature demand levels; A two-stage heat exchange unit, which includes two heat exchangers of different temperature levels, is used to absorb and utilize the waste heat generated by the photovoltaic panel 1 and to recover the waste heat generated by the user end of different temperature demand levels in a cascade manner and supply it to the user end of the next level of temperature demand for use; Among them, the heat pump unit 4 absorbs heat from the environment and transports it to the first-stage temperature-demand user end 3 through the first-stage heat exchanger 2. The first-stage heat exchanger 2 receives the waste heat generated by the photovoltaic panels 1 and the waste heat of the first-stage temperature-demand user end 3, and transports it to the secondary-stage temperature-demand user end 6 through the secondary-stage heat exchanger 5. The secondary-stage heat exchanger 5 receives the waste heat discharged from the first-stage heat exchanger 2.

[0024] In the above technical solution, the photovoltaic array serves as the energy generation source of the entire system. It is composed of several photovoltaic panels 1. The photovoltaic panels 1 utilize the principle of the photovoltaic effect to convert solar energy into electrical energy. Its advantages lie in being renewable, clean and environmentally friendly, reducing the dependence on traditional fossil energy, and reducing carbon emissions. Multiple photovoltaic panels 1 form an array, and in actual applications, the scale can be flexibly adjusted according to actual needs to meet the electrical energy requirements of the system in different scenarios. Whether it is a small residential house, or a large commercial building or industrial plant, the number and layout of the photovoltaic panels 1 can be reasonably configured to ensure stable power supply of the system. The heat pump unit 4 is driven by the electrical energy generated by the photovoltaic array and is the key equipment for heat conversion and transportation in the entire system. Its working principle is to absorb heat from the environment (air, water or soil) by consuming a small amount of electrical energy and raise its temperature to a higher level, so as to provide heat for user ends with different temperature demand levels. This method has higher energy utilization efficiency compared with the traditional method of directly burning energy to obtain heat. Taking an air-source heat pump as an example, it can absorb heat from low-temperature air, compress and heat it up through a compressor, and then transfer the heat to the user end for heating. Moreover, the heat pump unit 4 can adjust the temperature of the output heat according to the needs of user ends with different temperature demands, meeting the different temperature requirements in domestic hot water supply, space heating, and industrial production processes, improving the pertinence and flexibility of energy utilization.

[0025] In the above technical solution, the two-stage heat exchange unit includes heat exchangers of different temperature levels, which undertake the important task of waste heat recovery and cascade utilization of waste heat. The design of the heat exchanger realizes the efficient transfer of heat, and the setting of different temperature levels meets the requirements of different user terminals for heat quality. Among them, on the one hand, the first-stage heat exchanger 2 receives the heat absorbed and transported by the heat pump unit 4 from the environment and transfers it to the first-stage temperature-demand user terminal 3. On the other hand, it collects the waste heat generated by the photovoltaic panel 1. The first-stage heat exchanger 2 collects this waste heat and also receives the waste heat discharged from the first-stage temperature-demand user terminal 3. It further transports these heats to the next-stage heat exchanger 5 to achieve the preliminary recovery and redistribution of heat. Such a design not only improves the utilization rate of the waste heat of the photovoltaic panel 1 but also makes full use of the waste heat discharged from the user terminal, reducing energy waste. The next-stage heat exchanger 5 receives the waste heat discharged from the first-stage heat exchanger 2 and transports this waste heat to the next-stage temperature-demand user terminal 6. This way of cascading the recovery and utilization of waste heat greatly improves the comprehensive utilization rate of energy. In some industrial production processes, certain links have higher temperature requirements, while other links have relatively lower temperature requirements. Through the two-stage heat exchange unit, the waste heat discharged from the high-temperature user terminal can be processed by the next-stage heat exchanger 5 and supplied to the user terminal with lower temperature requirements for use, realizing the reasonable distribution and efficient utilization of heat between different user terminals.

[0026] In the above technical solution, the user terminals with different temperature requirements vary according to the heat requirements of users for different purposes. The following are several segmentation methods for the first-stage temperature-demand user terminals and the next-stage temperature-demand user terminals. First, segmented according to the temperature range, the first-stage temperature-demand user terminals are users with a temperature demand greater than 100 °C. Such user terminals usually require higher-temperature heat energy to meet specific process or production requirements. For example, in the chemical industry, some chemical reactions need to be carried out in a high-temperature environment; the next-stage temperature-demand user terminals are users with a temperature demand less than or equal to 100 °C. Such user terminals usually have certain temperature requirements but do not require too high a temperature, such as the heating system of buildings and the use of domestic hot water. Second, segmented according to the industry and application scenarios, the first-stage temperature-demand user terminals are high-temperature industrial production user terminals, such as the chemical and metallurgical industries, etc., and the next-stage temperature-demand user terminals are non-high-temperature industrial production user terminals, such as food processing, papermaking, building heating, temperature regulation of greenhouse greenhouses, preheating of irrigation water, etc.

[0027] An application example of the above technical solution is as follows: In a residential community, a photovoltaic heat recovery and reuse system is installed. The photovoltaic array consists of 500 high-efficiency monocrystalline silicon photovoltaic panels 1, which are laid on the roofs of public buildings in the community, with a total installed capacity of 100 kWp. The heat pump unit 4 selects an air-source heat pump with a power of 50 kW, which can operate stably at an ambient temperature of -15°C to 40°C; the two-stage heat exchange unit includes a plate-type primary heat exchanger 2 and a shell-and-tube secondary heat exchanger 5. During the day, when there is sufficient sunlight, the photovoltaic array generates electricity to drive the operation of the heat pump unit 4. The heat pump absorbs heat from the air around the community and heats the hot water to 60°C through the primary heat exchanger 2, and supplies it to users in the community who need hot water at a higher temperature, such as the public bathhouse in the community and some households with higher requirements for water temperature, to meet their daily bathing and domestic hot water needs. In this process, the primary heat exchanger 2 simultaneously collects the waste heat generated by the photovoltaic panels 1, and this waste heat further increases the temperature of the hot water, reducing the energy consumption of the heat pump. At the same time, the hot water after being used by the primary temperature-demand user end 3 drops to about 45°C, and its waste heat is recovered by the primary heat exchanger 2, and then the heat is transferred to users who need hot water at a lower temperature through the secondary heat exchanger 5, such as the heating system in the community, heating the heating water to 35°C - 40°C for indoor heating in winter. The secondary heat exchanger 5 receives the waste heat discharged from the primary heat exchanger 2, further increasing the temperature of the heating water and realizing the cascade utilization of waste heat. Through the operation of this system, the domestic hot water and heating demands in the community are effectively met, reducing the dependence on traditional gas water heaters and boilers and lowering the energy cost. According to statistics, compared with the traditional energy supply method, this community can save about 30,000 cubic meters of natural gas consumption per year, reduce carbon dioxide emissions by about 75 tons, and at the same time reduce the energy cost expenditure by about 40%.

[0028] In the above technical solution, the photovoltaic heat recovery and reuse system forms an efficient energy comprehensive utilization system by integrating the photovoltaic array, the heat pump unit 4 and the two-stage heat exchange unit, and it has at least the following beneficial effects: 1. The photovoltaic heat recovery and reuse system makes full use of the electric energy generated by the photovoltaic panels 1 to drive the heat pump unit 4 to absorb heat from the environment and supply heat to the user end; at the same time, the two-stage heat exchange unit recovers and cascades the waste heat of the photovoltaic panels 1 and the waste heat generated by user ends with different temperature demand levels, enabling the heat to be transferred between user ends with different temperature demands, reducing energy waste, greatly improving the comprehensive energy utilization rate; the waste heat and residual heat that might have been wasted are reused twice or even multiple times, increasing the energy output-input ratio of the entire system and reducing the energy cost; 2. The heat pump unit 4 can supply heat to the user terminals with different temperature demand levels, and the two-stage heat exchange unit further realizes the cascade distribution of heat, meeting the diversified energy consumption demands in different scenarios such as domestic hot water, heating, and industrial production, and improving the applicability and practicality of the system; whether it is an industrial production process with a relatively high temperature requirement or indoor heating and domestic hot water supply with a relatively low temperature requirement, the system can accurately provide thermal energy at an appropriate temperature. 3. The photovoltaic heat recovery and reuse system combines solar energy and environmental thermal energy, and multiple energy sources make the energy supply more stable and reliable; when the solar energy resources are sufficient, the electric energy generated by the photovoltaic array provides power for the heat pump unit 4; when the solar energy is insufficient, the heat pump unit 4 can still absorb heat from the environment to maintain operation, ensuring continuous and stable energy supply under different weather and season conditions. 4. Using solar energy as part of the energy input reduces the dependence on traditional fossil fuels, reduces pollutant emissions caused by burning fossil fuels, conforms to the concept of sustainable development, and plays a positive role in environmental protection; moreover, the efficient energy utilization method reduces the total energy consumption, indirectly reducing the negative impact on the environment during the energy production process; by recovering and reusing waste heat and excess heat, additional energy consumption is reduced, and the operating cost of the system is lowered; for enterprises and users, long-term use of this system can save a large amount of energy costs and improve economic benefits.

[0029] In another specific embodiment of the present invention, multiple solar panels are arranged in a matrix, and a spiral heat conduction channel is provided on the back of each photovoltaic panel 1. A heat conduction medium flows in the heat conduction channel, and the heat conduction medium absorbs the waste heat generated by the photovoltaic panel 1 and transfers the heat to the first-stage heat exchanger 2.

[0030] In the above technical solution, multiple photovoltaic panels 1 are arranged in a matrix. The matrix arrangement can make full use of the installation space and improve the power generation efficiency per unit area of the photovoltaic array. In a limited site, by reasonably planning the number of rows and columns of the matrix, the installation quantity of the photovoltaic panels 1 can be maximally increased, thereby enhancing the power generation capacity of the entire photovoltaic array. A spiral heat conduction channel is provided on the back of each photovoltaic panel 1, and a heat conduction medium flows in the heat conduction channel. The spiral design increases the flow path of the heat conduction medium on the back of the photovoltaic panel 1 and prolongs the contact time between the heat conduction medium and the photovoltaic panel 1. When the photovoltaic panel 1 generates electric energy under the illumination condition, a large amount of waste heat will inevitably be generated, and these waste heats will affect the power generation efficiency and service life of the photovoltaic panel 1. When the heat conduction medium flows in the spiral channel, it can fully absorb these waste heats and then transfer the absorbed heat to the first-stage heat exchanger 2 to realize the recovery and reuse of waste heat.

[0031] In the above technical solution, the spiral heat-conducting flow channel greatly increases the contact area and contact time between the heat-conducting medium and the photovoltaic panel 1. Compared with a simple straight flow channel, the spiral flow channel enables the heat-conducting medium to more fully absorb the waste heat generated by the photovoltaic panel 1, improving the waste heat collection efficiency. By extending the flow path of the heat-conducting medium, it ensures that the waste heat can be more thoroughly absorbed, reducing the accumulation of waste heat on the photovoltaic panel 1 and helping to maintain the good working state of the photovoltaic panel 1. Transferring the waste heat generated by the photovoltaic panel 1 to the first-stage heat exchanger 2 provides more energy for subsequent heat utilization. These waste heats can be mixed with other heat sources (such as the heat absorbed by the heat pump unit 4 from the environment) in the first-stage heat exchanger 2 to jointly provide heat for the first-stage temperature-demand user terminal 3, or through the coordinated operation of the two-stage heat exchange unit, further transfer the heat to the next-stage temperature-demand user terminal 6, thereby improving the energy utilization efficiency of the entire system and reducing energy waste. Timely removing the waste heat generated by the photovoltaic panel 1 helps to reduce the working temperature of the photovoltaic panel 1. Excessive temperature will cause the power generation efficiency of the photovoltaic panel 1 to decline, and long-term exposure to a high-temperature environment will also shorten the service life of the photovoltaic panel 1. Through the action of the heat-conducting flow channel and the heat-conducting medium, the temperature of the photovoltaic panel 1 is effectively reduced, enabling it to work within a more stable temperature range, improving the stability of the power generation efficiency, extending the service life of the photovoltaic panel 1, and reducing the cost of replacing the battery panel and the maintenance workload.

[0032] In another specific embodiment of the present invention, the photovoltaic array is composed of n battery panels connected in series and m groups of serially connected battery panels connected in parallel; The output end of the photovoltaic array is connected to a DC busbar box, and the DC busbar box aggregates the DC outputs of m groups of serially connected battery panels. The direct current output by the DC busbar box is connected to an inverter with a maximum power point tracking function; Among them, the method for realizing the maximum power point tracking function is as follows: S1. According to the open-circuit voltage, which is the theoretical upper limit value of the output voltage of the photovoltaic array, divide the working voltage range into multiple intervals, including a low-voltage area, a medium-voltage area, and a high-voltage area; S2. Set different perturbation step sizes in each interval, where the perturbation step size in the low-voltage area is greater than that in the medium-voltage area, and the perturbation step size in the medium-voltage area is greater than that in the high-voltage area; S3. Real-time monitor the output voltage and current of the photovoltaic array and calculate the current power; S4. Determine the interval to which the current voltage value belongs and select the corresponding perturbation step size; S5. Apply a voltage perturbation to adjust the working point of the photovoltaic array and compare the power change before and after the perturbation; if the power increases, maintain the perturbation direction; if the power decreases, reverse the perturbation direction; S6. Repeat the above steps until the photovoltaic array operates at the maximum power point.

[0033] In the above technical solution, the photovoltaic array is composed of n panels connected in series, and then m groups of such series-connected panels are connected in parallel. The purpose of series connection is to increase the voltage because in a series circuit, the total voltage is equal to the sum of the voltages of each panel; while parallel connection is to increase the current, and in a parallel circuit, the total current is equal to the sum of the currents of each branch. Through this combination of series and parallel connections, the output voltage and current of the photovoltaic array can be flexibly adjusted according to actual needs to adapt to the requirements of subsequent equipment. The output end of the photovoltaic array is connected to a DC busbar box, and the function of the DC busbar box is to aggregate the DC outputs of n groups of series-connected panels. Since the photovoltaic array is usually composed of multiple panels connected in series and parallel, there will be multiple DC output terminals. The DC busbar box centralizes these outputs, facilitating subsequent unified processing and transmission, and reducing the complexity of the circuit. The DC power output from the DC busbar box is connected to an inverter with the maximum power point tracking (MPPT) function. The main function of the inverter is to convert DC power into AC power to meet the needs of most electrical equipment and the power grid. The MPPT function is to keep the photovoltaic array operating near the maximum power point all the time, improving the power generation efficiency of the photovoltaic system.

[0034] In the above technical solution, the present invention further provides a method for implementing the maximum power point tracking function: S1: Division of the operating voltage range According to the open-circuit voltage, which is the theoretical upper limit value of the output voltage of the photovoltaic array, the operating voltage range is divided into multiple intervals, including a low voltage area, a medium voltage area, and a high voltage area. The open-circuit voltage refers to the output voltage of the photovoltaic array under no-load conditions, and it is an important reference value for the output voltage of the photovoltaic array. By dividing different voltage intervals, different control strategies can be adopted for different voltage ranges.

[0035] S2: Setting different perturbation step sizes Different perturbation step sizes are set within each interval. The perturbation step size in the low voltage area is larger than that in the medium voltage area, and the perturbation step size in the medium voltage area is larger than that in the high voltage area. The perturbation step size determines the amplitude of each adjustment of the operating point of the photovoltaic array. In the low voltage area, since it may be far from the maximum power point, a larger perturbation step size can enable the system to approach the maximum power point faster; while in the high voltage area, since it is already close to the maximum power point, a smaller perturbation step size can avoid over-adjustment and enable the system to operate more stably near the maximum power point.

[0036] S3: Real-time monitoring and power calculation Monitor the output voltage and current of the photovoltaic array in real time, and calculate the current power through the power calculation formula P = UI (where P is power, U is voltage, and I is current). This step is the basis for implementing the MPPT function. Only by accurately obtaining the current power in real time can the operating point be adjusted according to the power change.

[0037] S4: Determine the interval and select the perturbation step size Determine the interval to which it belongs according to the current voltage value and select the corresponding perturbation step size. By judging which interval the current voltage is in, the system can automatically select an appropriate perturbation step size to adjust the operating point, achieving adaptive control.

[0038] S5: Apply perturbation and compare powers Apply a voltage perturbation to adjust the operating point of the photovoltaic array and compare the power changes before and after the perturbation. If the power increases, it means that the current perturbation direction is correct, and the perturbation direction is maintained for continuous adjustment; if the power decreases, it means that the perturbation direction is incorrect, and the perturbation direction is reversed. This adjustment method based on power feedback can ensure that the system continuously approaches the maximum power point.

[0039] S6: Repeat the adjustment until the maximum power point is reached Repeat the above steps to continuously adjust the operating point of the photovoltaic array until the photovoltaic array operates at the maximum power point. Since environmental factors such as light intensity and temperature change continuously, the maximum power point will also move accordingly. Therefore, continuous adjustment is required to ensure that the photovoltaic array always operates near the maximum power point.

[0040] The advantages of the above implementation method are at least as follows: Through the MPPT function, the photovoltaic array can always operate near the maximum power point, making full use of solar energy resources and improving the power generation efficiency of the photovoltaic system. Especially when environmental conditions such as light intensity and temperature change, the system can quickly adaptively adjust, reducing power losses caused by environmental changes and enabling the photovoltaic system to output as much electrical energy as possible under various working conditions. By setting different perturbation step sizes according to different voltage ranges, adaptive control is achieved. When the distance from the maximum power point is far, a larger perturbation step size can be used to quickly approach the maximum power point and shorten the adjustment time; when approaching the maximum power point, a smaller perturbation step size can be used to prevent the system from oscillating back and forth near the maximum power point, enabling the system to operate more stably at the maximum power point. This adaptive adjustment ability improves the response speed and stability of the system. The photovoltaic array is composed of a series-parallel combination, then aggregated through a DC busbar box, and finally connected to an inverter with MPPT function. This system structure is clear and reasonable. The series-parallel combination can flexibly adjust the output voltage and current, the DC busbar box reduces the line complexity, and the MPPT inverter ensures the efficient operation of the system. Each part works together to improve the reliability and performance of the entire photovoltaic system. Improving the power generation efficiency means that more electrical energy can be obtained under the same lighting conditions, which is equivalent to reducing the production cost per unit of electrical energy. At the same time, the adaptive adjustment ability and stability of the system reduce the maintenance cost and economic losses caused by power losses, reducing the overall operating cost of the photovoltaic system.

[0041] In another specific embodiment of the present invention, according to the open-circuit voltage, which is the theoretical upper limit value of the output voltage of the photovoltaic array, the working voltage range is divided into multiple intervals as follows: Low voltage region: 0 to 50% of the open-circuit voltage; Medium voltage region: 50% to 80% of the open-circuit voltage; and, High voltage region: 80% to 100% of the open-circuit voltage.

[0042] In the above technical solution, the open-circuit voltage refers to the output voltage of the photovoltaic array under no-load conditions, which represents the maximum voltage value that the photovoltaic array can output under the current lighting and temperature conditions and is an important parameter of the output characteristics of the photovoltaic array. Dividing the working voltage interval based on the open-circuit voltage can intuitively reflect the position of the current working point of the photovoltaic array relative to its maximum output capacity, thus providing a clear reference for subsequent control strategies. The specific ranges of each voltage interval are as follows: Low voltage region (0 to 50% of the open-circuit voltage): When the output voltage of the photovoltaic array is in this interval, it indicates that its working point is far from the maximum power point. This may be due to low light intensity, high temperature, or excessive load. In this interval, the output power of the photovoltaic array is relatively low and there is still a large room for improvement.

[0043] Medium voltage region (50% - 80% of open - circuit voltage): In this region, the operating point of the photovoltaic array gradually approaches the maximum power point. As the voltage increases, the output power also continuously increases, but it still has not reached the maximum value. At this stage, the operating point needs to be adjusted more precisely to further increase the output power.

[0044] High voltage region (80% - 100% of open - circuit voltage): When the output voltage is in this region, the photovoltaic array is already very close to the maximum power point. At this time, the change in output power is very sensitive to the adjustment of the operating point, and a smaller adjustment amplitude needs to be used to avoid crossing the maximum power point and causing the output power to decrease.

[0045] When implementing the MPPT function, determine the voltage region to which the current photovoltaic array belongs according to its output voltage, and then select the corresponding control strategy. For example, in the low - voltage region, use a larger perturbation step size to quickly approach the maximum power point; in the medium - voltage region, appropriately reduce the perturbation step size for more precise adjustment; in the high - voltage region, use an even smaller perturbation step size to ensure that the system operates stably near the maximum power point.

[0046] Such settings for each voltage range are beneficial for quickly approaching the maximum power point and achieving precise adjustment of MPPT. Setting a larger voltage range (0 - 50% open-circuit voltage) and adopting a larger perturbation step size in the low voltage region enables the photovoltaic array to quickly approach the maximum power point when it is far from it. This can reduce the adjustment time of the system in the region far from the maximum power point, improve the overall response speed, and reach a higher output power faster; the division of the medium voltage region (50% - 80% open-circuit voltage) and the high voltage region (80% - 100% open-circuit voltage) allows for the adoption of different smaller perturbation step sizes according to different degrees of proximity when approaching the maximum power point. Appropriately reducing the step size in the medium voltage region for preliminary precise adjustment and further reducing the step size in the high voltage region for fine adjustment avoid crossing the maximum power point due to too large an adjustment amplitude, improving the accuracy of MPPT. At the same time, it can enhance the stability of the system and avoid oscillations. By reasonably dividing the voltage range and adopting different perturbation step sizes, it is possible to prevent the system from experiencing excessive oscillations near the maximum power point. Adopting an extremely small perturbation step size in the high voltage region enables the system to stably operate near the maximum power point, reducing power fluctuations caused by environmental factor changes or control errors and improving the stability of the system output power. Finally, through efficient and precise MPPT control, the photovoltaic array can be made to operate as close as possible to the maximum power point under different illumination and temperature conditions, fully exploiting the power generation potential of the photovoltaic array, improving the conversion efficiency of solar energy, thereby increasing the power generation of the entire photovoltaic system and optimizing the energy utilization efficiency. Improving the energy utilization efficiency means obtaining more electrical energy output under the same investment and light resources, which is equivalent to reducing the production cost per unit of electrical energy. The stable power output also reduces equipment losses and maintenance costs caused by power fluctuations, overall reducing the operating cost of the photovoltaic system.

[0047] In another specific embodiment of the present invention, setting different perturbation step sizes within each interval includes: The step size in the low voltage region is 2.0V; The step size in the medium voltage region is 1.0V; The step size in the high voltage region is 0.5V.

[0048] In the above technical solution, during the maximum power point tracking (MPPT) process of the photovoltaic thermal recovery and reuse system, setting specific perturbation step sizes according to different intervals of the working voltage of the photovoltaic array is a key link to achieve efficient and accurate tracking of the maximum power point. Adopting a larger perturbation step size in the low voltage region can enable the photovoltaic array to quickly move the operating point when it is far from the maximum power point, greatly shortening the time required to approach the maximum power point. As the operating point gradually approaches the maximum power point, gradually reducing the perturbation step size can achieve precise adjustment of the operating point at different stages. In the medium voltage region and the high voltage region, a smaller step size can capture power changes more precisely, avoiding missing the maximum power point due to too large an adjustment amplitude, ensuring that the system can track the maximum power point as accurately as possible and operate stably near this point, thereby improving the overall power generation efficiency. Reasonably setting the perturbation step sizes in different intervals avoids power oscillations caused by too large a step size when approaching the maximum power point. Adopting an extremely small step size in the high voltage region makes the adjustment of the system near the maximum power point smoother, reducing power fluctuations, providing a stable energy input for subsequent heat recovery and utilization, and facilitating the stable operation of the entire photovoltaic thermal recovery and reuse system. Compared with the method of adopting a fixed small step size, this rapid approximation strategy can enable the system to start operating at a higher power level faster. Especially when the light intensity suddenly changes or at the initial stage of system startup, it can quickly improve the power generation efficiency. Changes in environmental factors such as light intensity and temperature will cause the maximum power point of the photovoltaic array to move. This strategy of setting different perturbation step sizes based on intervals can adaptively adjust according to the interval where the current working voltage is located, and can quickly and accurately track the new maximum power point under different environmental conditions, improving the system's adaptability to environmental changes.

[0049] In another specific embodiment of the present invention, the steps of applying a voltage perturbation in step S5 to adjust the operating point of the photovoltaic array and comparing the power changes before and after the perturbation include: S51. Increase or decrease a perturbation step size based on the current voltage to obtain a new voltage value; S52. Adjust the operating point of the photovoltaic array to the new voltage value; S53. Measure the new power value and compare it with the power value before the perturbation.

[0050] In the above technical solution, the steps of applying a voltage perturbation to adjust the operating point of the photovoltaic array and comparing the power changes before and after the perturbation are specifically as follows: S51: Obtain a new voltage value Based on the operating voltage of the current photovoltaic array, the voltage is increased or decreased according to the perturbation step size of the corresponding voltage range set in advance, so as to obtain a new voltage value. For example, if the current operating voltage is in the low-voltage region and the perturbation step size is 2.0V, the system will decide whether to add 2.0V or subtract 2.0V from the current voltage to obtain the new voltage value. This decision is usually made in a certain logical order or randomly, aiming to explore the impact of voltage adjustments in different directions on power; S52: Adjust the operating point to the new voltage value After obtaining the new voltage value, the system will adjust the operating point of the photovoltaic array to this new voltage value by controlling devices such as inverters. This process involves precise control of the output circuit of the photovoltaic array to ensure that it can operate stably at the newly set voltage. By adjusting the operating point, the combination of the output current and voltage of the photovoltaic array is changed, thereby affecting its output power.

[0051] S53: Compare the power change After the operating point of the photovoltaic array is adjusted to the new voltage value and stabilized, the system will measure the output power at this time to obtain a new power value. Then this new power value is compared with the power value before the voltage perturbation. The result of the comparison will determine the subsequent operation direction. If the new power value is greater than the power value before the perturbation, it means that the current voltage adjustment direction is correct and can make the photovoltaic array closer to the maximum power point; on the contrary, if the new power value is less than the power value before the perturbation, it means that the adjustment direction is wrong and the adjustment direction needs to be changed.

[0052] In the above technical solution, by continuously applying voltage perturbations and comparing the power changes, the system can gradually find the maximum power point of the photovoltaic array. Each perturbation is a trial. According to the increase or decrease of power, it is judged whether the adjustment direction is correct, and then the operating point is continuously optimized. When environmental factors such as light intensity and temperature change, this dynamic adjustment mechanism can enable the photovoltaic array to quickly adapt to the changes and always operate near the maximum power point, improving the conversion efficiency of solar energy and increasing the power generation. Moreover, this method does not depend on a specific photovoltaic array model or environmental conditions and has strong adaptability. Whether it is an array composed of different types of photovoltaic panels 1 or under different light and temperature conditions, the maximum power point can be tracked through this perturbation adjustment method based on power comparison. As long as the power change can be measured, correct adjustments can be made according to the comparison results, ensuring the stable operation of the system in various complex environments; by gradually adjusting the voltage in small increments, only changing one perturbation step each time, a large impact on the operating point of the photovoltaic array is avoided, reducing the fluctuations and unstable factors of the system. When approaching the maximum power point, a smaller perturbation step can make the system more stably stay near the maximum power point and will not cause a large power drop due to excessive adjustment, ensuring the stability of the output power of the photovoltaic system.

[0053] In another specific embodiment of the present invention, the diversion channel is bonded to the back of the photovoltaic panel 1 with thermal conductive silicone, the bonding thickness is 0.5 mm, the coverage rate is ≥95%, and a flow channel outlet joint is provided at the end of each thermal conductive flow channel, which is connected to the stainless steel corrugated hose by thread; each stainless steel corrugated hose is aggregated into the stainless steel header through the multi-pass header interface, and the header is connected to the inlet of the first-stage heat exchanger 2 through a flange.

[0054] In the above technical solution, the heat-conducting runner is bonded to the back of the photovoltaic panel 1 by heat-conducting silica gel, with a bonding thickness of 0.5 mm and a coverage rate ≥ 95%. The heat-conducting silica gel has good heat-conducting performance and can effectively transfer the waste heat generated by the photovoltaic panel 1 to the heat-conducting medium in the heat-conducting runner. The 0.5-mm bonding thickness is optimized, which can not only ensure sufficient heat-conducting area but also not increase the thermal resistance due to excessive thickness and affect the heat transfer efficiency. The high coverage rate means that the contact area between the heat-conducting runner and the photovoltaic panel 1 is large, which can collect the waste heat generated by the panel to the greatest extent and ensure the high efficiency of waste heat recovery. A runner outlet joint is provided at the end of each heat-conducting runner, and this joint is threadedly connected to the stainless-steel corrugated hose. The runner outlet joint provides a channel for the heat-conducting medium to flow out of the heat-conducting runner. The threaded connection method has good sealing performance and connection strength, which can prevent the leakage of the heat-conducting medium and ensure the normal operation of the system. The stainless-steel corrugated hose has certain flexibility and corrosion resistance, can adapt to different installation environments and position changes, and is convenient for the layout and connection of the system. Each stainless-steel corrugated hose is aggregated into the stainless-steel header through the multi-pass header interface. The multi-pass header interface can gather the heat-conducting media in multiple stainless-steel corrugated hoses together to achieve the aggregation of multiple paths of heat-conducting media. The stainless-steel header has good strength and corrosion resistance and can withstand a certain pressure to ensure the stable flow of the heat-conducting medium during the aggregation process. The header is connected to the inlet of the first-stage heat exchanger 2 through a flange. Flange connection is a commonly used pipeline connection method, which has the advantages of tight connection, good sealing performance, convenient disassembly and maintenance, etc. Through flange connection, the stainless-steel header can be firmly connected to the first-stage heat exchanger 2 to transport the aggregated heat-conducting medium to the heat exchanger for heat exchange.

[0055] As Figure 1 or Figure 2 In another specific embodiment of the present invention, both the first-stage heat exchanger 2 and the sub-stage heat exchanger 5 are shell-and-tube heat exchangers, each including a shell, two groups of independent tube passes, and a shell pass; The outlet of the heat-conducting runner is connected to the inlet of the first group of tube passes of the first-stage heat exchanger 2. After the heat-conducting medium that has completed heat exchange flows out from the outlet of the first group of tube passes, it enters the first group of independent tube passes of the sub-stage heat exchanger 5, passes through the Y-shaped shunt tube, and is finally redistributed to the inlet of the heat-conducting runner of each photovoltaic panel 1 to achieve circulation; The outlet of the condenser of the heat pump is connected to the inlet of the second tube pass of the first-stage heat exchanger 2. The refrigerant that has completed heat exchange flows out from the outlet of the second tube pass of the first-stage heat exchanger 2, passes through the electronic expansion valve, and returns to the inlet of the evaporator of the heat pump to achieve circulation; Connect the outlet end of the shell side of the first-stage heat exchanger 2 to the inlet of the liquid of the first-stage temperature-demand user end 3. The outlet of the liquid of the first-stage temperature-demand user end 3 is first connected to the inlet of the second set of tube sides of the next-stage heat exchanger 5, and then, after passing through the outlet of the second set of tube sides of the next-stage heat exchanger 5, it is connected to the inlet of the liquid of the shell side of the next-stage heat exchanger 5; Connect the outlet end of the shell side of the next-stage heat exchanger 5 to the inlet of the liquid of the second-stage temperature-demand user end, and connect the outlet of the liquid of the second-stage temperature-demand user end to the inlet end of the shell side of the first-stage heat exchanger 2 to achieve circulation.

[0056] In the above technical solution, both the first-stage heat exchanger 2 and the next-stage heat exchanger 5 adopt shell-and-tube heat exchangers. This structure consists of a shell, two independent tube sides, and a shell side. The tube side refers to the channel through which the fluid flows in the pipeline, while the shell side refers to the channel through which the fluid flows in the space between the shell and the pipeline. The two independent tube sides can allow different fluids to flow in the heat exchanger to achieve various heat exchange processes.

[0057] In the above technical solution, the heat-conducting medium flows out from the heat-conducting channel outlet of the photovoltaic panel 1 and enters the inlet of the first group of tube passes of the first-stage heat exchanger 2. Inside the first group of tube passes, the heat-conducting medium exchanges heat with the fluid in the shell pass, releasing the waste heat absorbed from the photovoltaic panel 1. The heat-conducting medium that has completed heat exchange flows out from the outlet of the first group of tube passes and then enters the first group of independent tube passes of the next-stage heat exchanger 5 for heat exchange again. After passing through the next-stage heat exchanger 5, the heat-conducting medium is redistributed to the heat-conducting channel inlets of each photovoltaic panel 1 through a Y-shaped shunt pipe (which can also be replaced by a multi-head shunt pipe according to the number of photovoltaic panels 1), completing a cycle and continuing to absorb the waste heat generated by the photovoltaic panel 1. The high-temperature and high-pressure refrigerant discharged from the condenser outlet of the heat pump enters the inlet of the second tube pass of the first-stage heat exchanger 2. Inside the second tube pass, the refrigerant exchanges heat with the fluid in the shell pass and its temperature decreases after releasing heat. The refrigerant that has completed heat exchange flows out from the outlet of the second tube pass of the first-stage heat exchanger 2, passes through an electronic expansion valve, and the electronic expansion valve throttles and depressurizes the refrigerant to make it in a low-temperature and low-pressure state. The depressurized refrigerant returns to the inlet of the evaporator of the heat pump, absorbs environmental heat in the evaporator, and becomes a high-temperature and high-pressure refrigerant again, completing a cycle. The hot fluid flowing out from the shell pass outlet end of the first-stage heat exchanger 2 enters the liquid inlet of the first-stage temperature-demand user end 3, providing heat for this user end. The liquid after being used by the first-stage temperature-demand user end 3 flows out from the liquid outlet, first enters the inlet of the second group of tube passes of the next-stage heat exchanger 5, exchanges heat with the fluid in the shell pass inside the tube pass, and further releases the waste heat. After flowing out from the outlet of the second group of tube passes of the next-stage heat exchanger 5, the liquid enters the liquid inlet of the shell pass of the next-stage heat exchanger 5 for heat exchange again. The liquid flowing out from the shell pass outlet end of the next-stage heat exchanger 5 enters the liquid inlet of the second-stage temperature-demand user end, providing heat at a lower temperature for this user end. The liquid after being used by the second-stage temperature-demand user end flows out from the liquid outlet and is connected to the shell pass inlet end of the first-stage heat exchanger 2, completing a cycle.

[0058] In the above technical solution, by combining the heat-conducting medium circulation with the user-side liquid circulation, the waste heat generated by the photovoltaic panel 1 is fully recovered and transferred to the user-side with different temperature requirements, realizing the cascade utilization of heat. This method improves the comprehensive utilization rate of energy and reduces energy waste; the cooperation between the heat pump and the heat exchanger enables the effective utilization of the heat in the environment, further increasing the heat supply of the system and improving the energy efficiency of the entire system. The two sets of independent tube-side and shell-side structures allow different fluids to conduct independent heat exchange in the heat exchanger. This enables the system to flexibly adjust the degree of heat exchange according to the temperature requirements of different user-sides and achieve precise heat supply to user-sides with different temperature requirements. For example, the user-side 3 with the first-level temperature requirement needs heat at a higher temperature, while the user-side with the second-level temperature requirement can utilize the waste heat. By reasonably designing the heat exchange process, the diverse requirements of different user-sides can be met. More importantly, the design of this system has good scalability, and the number of devices such as the photovoltaic panel 1, the heat pump, and the heat exchanger can be increased or decreased according to actual needs to adapt to different scales of energy demand. At the same time, for user-sides with different temperature requirements, their requirements can also be met by adjusting the heat exchange process and parameters, showing strong adaptability.

[0059] Such as Figure 2 , in another specific embodiment of the present invention, the photovoltaic heat recovery and reuse system further includes a heat storage and energy storage mechanism 7, which is used to store the excess heat of the multi-stage heat exchange unit and provide heat during peak heat demand or when the heat supply of the heat pump unit 4 is insufficient. The core function of the heat storage and energy storage mechanism 7 is to store the excess heat generated by the multi-stage heat exchange unit. During the operation of the photovoltaic heat recovery and reuse system, the multi-stage heat exchange unit continuously conducts heat exchange. Sometimes, the heat generation amount may be greater than the immediate demand of the user-side. At this time, the excess heat is collected and stored by the heat storage and energy storage mechanism 7 through the Y-shaped shunt pipe. An electromagnetic valve is set between the heat storage and energy storage mechanism 7 and the multi-stage heat exchange unit. When the heat generated by the multi-stage heat exchange unit exceeds the current heat demand of the user-side, the set electromagnetic valve opens, and the heat storage and energy storage mechanism 7 starts to work to store the excess heat. Conversely, the set electromagnetic valve closes. During certain time periods, such as at night in winter or during the business hours of large commercial premises, the heat demand of the user-side will increase significantly, exceeding the immediate heat supply capacity of the multi-stage heat exchange unit and the heat pump unit 4. At this time, the heat storage and energy storage mechanism 7 will release the stored heat and supplement it to the heating system to meet the heat demand of the user-side; or when the heat supply capacity of the heat pump unit 4 decreases due to low ambient temperature, equipment failure, etc., the heat storage and energy storage mechanism 7 will play a role, release the stored heat, maintain the heating stability of the system, and ensure the normal heat use of the user-side.

[0060] In the above technical solution, the heat storage and energy storage mechanism 7 is provided to enable the system to effectively utilize the excess heat generated by the multi-stage heat exchange unit, avoiding waste of heat. It stores heat when the heat generation is excessive and releases it during peak demand periods, achieving reasonable allocation of heat and improving the energy utilization efficiency of the entire photovoltaic heat recovery and reuse system. In the case of peak heat demand or insufficient heat supply from the heat pump unit 4, the heat storage and energy storage mechanism 7 can promptly provide supplementary heat to ensure that the heat demand at the user end is met. This greatly enhances the stability and reliability of the system and reduces the impact on the normal life or production of users caused by insufficient heat supply. For example, on a cold winter night, even if the heat pump unit 4 has a reduced heating capacity due to low ambient temperature, the heat storage and energy storage mechanism 7 can ensure that the indoor temperature remains within a comfortable range. The operation of the photovoltaic heat recovery and reuse system is affected by various factors such as light intensity and ambient temperature, and the heat demand at the user end also varies with time and season. The presence of the heat storage and energy storage mechanism 7 enables the system to better adapt to these operating conditions and environmental changes, ensuring stable operation of the system in various situations and improving the adaptability and flexibility of the system. By reasonably utilizing the heat storage and energy storage mechanism 7, the system can store heat during periods of low electricity prices (such as at night) and reduce its dependence on grid electricity during periods of high electricity prices (such as during the daytime electricity peak), thereby reducing the operating cost of the system. In addition, the heat storage and energy storage mechanism 7 can also reduce the frequent start and stop of equipment such as the heat pump unit 4, extend the service life of the equipment, and reduce the equipment maintenance cost.

[0061] The number of devices and the processing scale described here are used to simplify the description of the present invention. Applications, modifications, and variations of the photovoltaic heat recovery and reuse system of the present invention will be obvious to those skilled in the art.

[0062] Although the embodiments of the present invention have been disclosed as above, they are not limited to only the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details and the illustrated and described examples here.

Claims

1. Photovoltaic heat recovery and reuse system, characterized in that: include: a photovoltaic array, which includes a plurality of photovoltaic panels; Heat pump units, which are driven by electricity generated by photovoltaic arrays, are used to absorb heat from the environment and supply it to users with different temperature demand levels; A two-stage heat exchange unit, which includes two heat exchangers of different temperature levels, is used to absorb and utilize the waste heat generated by the photovoltaic panels and to recover the waste heat generated by the user ends of different temperature demand levels in a cascade manner and supply it to the user ends of the next level of temperature demand for use; Among them, the heat pump unit absorbs heat from the environment and transmits it to the first-level temperature demand user end through the first-level heat exchanger. The first-level heat exchanger receives the waste heat generated by the photovoltaic panels and the residual heat of the first-level temperature demand user end, and transmits it to the next-level temperature demand user end through the next-level heat exchanger. The next-level heat exchanger receives the residual heat discharged by the first-level heat exchanger.

2. The photovoltaic heat recovery and reuse system according to claim 1, characterized in that: A plurality of photovoltaic panels are arranged in a matrix, and a spiral heat conduction channel is provided on the back of each photovoltaic panel. A heat conduction medium flows in the heat conduction channel. The heat conduction medium absorbs waste heat generated by the photovoltaic panel and transfers the heat to the first-stage heat exchanger.

3. The photovoltaic heat recovery and reuse system according to claim 1, characterized in that: The photovoltaic array is formed by connecting n solar panels in series, and then connecting m groups of solar panels in series in parallel; The output end of the PV array is connected to a DC combiner box, which aggregates the DC outputs of m groups of series-connected solar panels. The DC power output by the DC combiner box is connected to an inverter with a maximum power point tracking function. Among them, the method for realizing the maximum power point tracking function is as follows: S1. According to the theoretical upper limit open circuit voltage of the output voltage of the photovoltaic array, the operating voltage range is divided into multiple intervals, including a low voltage area, a medium voltage area and a high voltage area; S2. Set different perturbation step sizes in each interval, where the perturbation step size in the low voltage area is larger than that in the medium voltage area, and the perturbation step size in the medium voltage area is larger than that in the high voltage area; S3, real-time monitoring of the output voltage and current of the photovoltaic array, and calculation of the current power; S4. Determine the interval according to the current voltage value and select the corresponding disturbance step size; S5, apply voltage disturbance, adjust the working point of the photovoltaic array, and compare the power change before and after the disturbance; if the power increases, maintain the disturbance direction; if the power decreases, reverse the disturbance direction; S6. Repeat the above steps until the photovoltaic array operates at the maximum power point.

4. The photovoltaic heat recovery and reuse system according to claim 3, characterized in that: According to the theoretical upper limit of the output voltage of the photovoltaic array, the open circuit voltage, the operating voltage range is divided into several intervals as follows: Low voltage area: 0~50% of open circuit voltage; Medium voltage region: 50%~80% of the open circuit voltage; and, High voltage area: 80%~100% of open circuit voltage.

5. The photovoltaic heat recovery and reuse system according to claim 3, characterized in that: Setting different perturbation step sizes in each interval includes: The step size in the low voltage region is 2.0V; The step size in the medium voltage region is 1.0V; The step size in the high voltage region is 0.5V.

6. The photovoltaic heat recovery and reuse system according to claim 3, characterized in that: The steps of applying voltage disturbance, adjusting the working point of the photovoltaic array, and comparing the power changes before and after the disturbance in step S5 include: S51, increasing or decreasing a disturbance step size based on the current voltage to obtain a new voltage value; S52, adjusting the working point of the photovoltaic array to a new voltage value; S53, measuring a new power value, and comparing it with the power value before the disturbance.

7. The photovoltaic heat recovery and reuse system according to claim 2, characterized in that: The flow channel is bonded to the back of the photovoltaic panel by thermal conductive silicone, with a bonding thickness of 0.5 mm and a coverage rate of ≥95%. A flow channel outlet joint is provided at the end of each thermal conductive flow channel, which is threadedly connected to a stainless steel corrugated hose; each stainless steel corrugated hose is collected into a stainless steel header through a multi-pass header interface, and the header is connected to the inlet of the first-stage heat exchanger through a flange.

8. The photovoltaic heat recovery and reuse system according to claim 1 or 7, characterized in that: The first-stage heat exchanger and the second-stage heat exchanger are both shell and tube heat exchangers, each comprising a shell, two sets of independent tube passes and a shell pass; The outlet of the heat transfer channel is connected to the inlet of the first group of tubes of the first-stage heat exchanger. After the heat transfer medium has completed the heat exchange, it flows out from the outlet of the first group of tubes and enters the first group of independent tubes of the next-stage heat exchanger. It passes through the Y-shaped flow divider and is finally distributed to the inlet of the heat transfer channel of each photovoltaic panel to realize circulation. The condenser outlet of the heat pump is connected to the second tube side inlet of the first stage heat exchanger. The refrigerant that has completed the heat exchange flows out from the second tube side outlet of the first stage heat exchanger, passes through the electronic expansion valve, and returns to the evaporator inlet of the heat pump to realize the circulation. The outlet end of the shell side of the first-stage heat exchanger is connected to the liquid inlet of the first-stage temperature demand user end. The liquid outlet of the first-stage temperature demand user end is first connected to the second group of tube side inlet of the next-stage heat exchanger, and then connected to the liquid inlet of the shell side of the next-stage heat exchanger through the second group of tube side outlet of the next-stage heat exchanger; The outlet end of the shell side of the next-stage heat exchanger is connected to the liquid inlet of the second-stage temperature demand user end, and the liquid outlet of the second-stage temperature demand user end is connected to the inlet end of the shell side of the first-stage heat exchanger to realize circulation.

9. The photovoltaic heat recovery and reuse system according to claim 1, characterized in that: It also includes a heat storage mechanism, which is used to store excess heat from the multi-stage heat exchange unit to provide heat when the heat demand peaks or the heat pump unit is insufficient.

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