PVT heat pump system and water heater

Abstract

The utility model discloses a PVT heat pump system and a water heater. The system further comprises a second condenser, an electromagnetic valve, a second electronic expansion valve, a third electronic expansion valve, a first three-way valve and a second three-way valve. According to the PVT heat pump system, the structure of the PVT heat pump system is improved, the condenser and other components are additionally arranged, different branches are set up, based on the novel PVT heat pump system structure, high-temperature hot water of 65-70 DEG C can be produced, the requirements for hot water of 65 DEG C or above in the industries of hot spring hotels, metal processing, food, chemical engineering and the like are met, and when the water temperature of the system is 50 DEG C or above, the energy consumption of the system is reduced. And relatively high COP performance is still realized. In addition, the new PVT heat pump system can perform heating while defrosting, extra mains supply is almost not needed to be provided for defrosting, and the electricity utilization cost of a user is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to heat pump system technical field, specifically, relate to a kind of PVT heat pump system, water heater. BACKGROUND

[0002] The highest hot water produced by current conventional air energy heat pump and existing PVT heat pump is 60 ℃, which is difficult to meet the demand of more than 65 ℃ hot water in industries such as hot spring hotel, metal processing, food and chemical industry, and when the water temperature of the unit reaches 50 ℃ or above, the system has problems such as high condensing temperature, large compression ratio and system performance decline.

[0003] In addition, the current conventional air energy heat pump system uses reverse cycle defrosting method to solve the problem of frost formation on the heat exchanger in winter, which will result in the inability to heat during defrosting, affecting user experience, and increasing system energy consumption.

[0004] In view of the problems that the PVT heat pump system in the prior art cannot produce high-temperature hot water and cannot heat during defrosting, no effective solution has been proposed so far. SUMMARY

[0005] The PVT heat pump system and water heater provided in the embodiments of the present utility model solve the problem that the PVT heat pump system in the prior art cannot produce high-temperature hot water and cannot heat during defrosting.

[0006] To solve the above technical problems, the present utility model provides a PVT heat pump system, which comprises a compressor, a first condenser, a fin heat exchanger, a first electronic expansion valve connected in sequence, and a PVT assembly connected in parallel with the fin heat exchanger.

[0007] A second condenser is arranged on a first branch, one end of the first branch is arranged on a pipeline between the compressor and the first condenser, and the other end is arranged on a pipeline between the first condenser and the fin heat exchanger.

[0008] An electromagnetic valve is arranged on the water inlet pipeline of the second condenser.

[0009] A second electronic expansion valve is arranged on the first branch and between the compressor and the second condenser.

[0010] A third electronic expansion valve is arranged on a second branch, one end of the second branch is arranged on a pipeline between the compressor and the first condenser, and the other end is arranged on a pipeline between the fin heat exchanger and the first electronic expansion valve.

[0011] A first three-way valve is connected to the first condenser at a port a, connected to the second condenser at a port b, and connected to tap water at a port c.

[0012] A second three-way valve is arranged on a pipeline between the first condenser and the fin heat exchanger, and the a port of the second three-way valve is connected to the fin heat exchanger, and the b port and the c port of the second three-way valve are connected to the first condenser.

[0013] Further, the system further comprises:

[0014] A pressure sensor is arranged at an exhaust port of the compressor.

[0015] A temperature sensor is arranged at a water outlet of the first condenser.

[0016] An irradiance meter is arranged at the PVT assembly.

[0017] Further, the b port and the c port of the second three-way valve are both one-way valves.

[0018] The utility model further provides a water heater, wherein the water heater comprises the PVT heat pump system.

[0019] The technical scheme of the utility model improves the structure of the PVT heat pump system, adds a second condenser, a solenoid valve, a second electronic expansion valve and a first three-way valve, further adds a third electronic expansion valve and a second three-way valve and other components, builds different branches, and based on the new PVT heat pump system structure, can produce high-temperature hot water of 65-70 DEG C, meets the demand of hot spring hotels, metal processing, food and chemical industry and other industries for hot water above 65 DEG C, and the system still has higher COP performance when the water temperature is 50 DEG C and above. In addition, the new PVT heat pump system can also heat while defrosting, and almost no additional mains electricity is needed for defrosting, reducing the electricity cost of users. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a structure schematic view of the PVT heat pump system according to the utility model embodiment.

[0021] Reference signs:

[0022] Compressor 1, first condenser 2, fin heat exchanger 3, first electronic expansion valve 4, PVT assembly 5, second condenser 6, solenoid valve 7, second electronic expansion valve 8, third electronic expansion valve 9, first three-way valve 10, second three-way valve 11, pressure sensor 12, temperature sensor 13, irradiance meter 14. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0024] The terminology used in the embodiments of this utility model is for the purpose of describing particular embodiments only and is not intended to limit the utility model. The singular forms “a,” “the,” and “the” used in the embodiments of this utility model and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0025] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0026] It should be understood that although the terms first, second, third, etc., may be used to describe the electronic expansion valve in the embodiments of this utility model, these should not be limited to these terms. These terms are only used to distinguish the electronic expansion valves. For example, without departing from the scope of the embodiments of this utility model, the first electronic expansion valve may also be referred to as the second electronic expansion valve, and similarly, the second electronic expansion valve may also be referred to as the first electronic expansion valve.

[0027] Depending on the context, the words “if” or “suppose” as used here can be interpreted as “when” or “in response to determination” or “in response to detection.” Similarly, depending on the context, the phrases “if determination” or “if detection (of the stated condition or event)” can be interpreted as “when determination” or “in response to determination” or “when detection (of the stated condition or event)” or “in response to detection (of the stated condition or event).”

[0028] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0029] The optional embodiments of the utility model will be explained in detail below with reference to the drawings.

[0030] Embodiment 1

[0031] Figure 1 It is a structure schematic view of the PVT heat pump system according to the embodiment of the utility model, Figure 1 The solid line represents the refrigerant path, and the dotted line represents the water path, as shown in Figure 1 The PVT heat pump system comprises a compressor 1, a first condenser, a fin heat exchanger 3, a first electronic expansion valve 4 connected in sequence, and a PVT assembly 5 connected in parallel with the fin heat exchanger 3.

[0032] The PVT heat pump system is a heat pump system based on PVT (photovoltaic-thermal) technology, which can realize heating and refrigeration through the use of solar energy. The PVT assembly is a photovoltaic-thermal assembly, Figure 1 In the embodiment, the PVT assembly 5 comprises PVT1, PVT2, …, PVTn, n represents the number of PVT plates, and the plurality of PVT plates are connected in parallel to form the PVT assembly, and the PVT assembly is connected in parallel with the fin heat exchanger.

[0033] The PVT heat pump system further comprises:

[0034] A second condenser 6 is arranged on the first branch, one end of the first branch is arranged on the pipeline between the compressor 1 and the first condenser, and the other end is arranged on the pipeline between the first condenser and the fin heat exchanger 3.

[0035] An electromagnetic valve 7 is arranged on the water inlet pipeline of the second condenser 6.

[0036] A second electronic expansion valve 8 is arranged on the first branch and arranged between the compressor 1 and the second condenser 6.

[0037] A third electronic expansion valve 9 is arranged on the second branch, one end of the second branch is arranged on the pipeline between the compressor 1 and the first condenser, and the other end is arranged on the pipeline between the fin heat exchanger 3 and the first electronic expansion valve 4.

[0038] A first three-way valve 10, its a port is connected with the first condenser, its b port is connected with the second condenser 6, and its c port is connected with tap water.

[0039] A second three-way valve 11 is arranged on the pipeline between the first condenser and the fin heat exchanger 3, its a port is connected with the fin heat exchanger 3, and its b port and c port are connected with the first condenser.

[0040] In the structure of the existing heat pump system, normal temperature tap water directly accesses the first condenser and exchanges heat through the first condenser. The PVT heat pump system of the embodiment is additionally provided with a second condenser 6, an electromagnetic valve 7, a second electronic expansion valve 8 and a first three-way valve 10. When the electromagnetic valve 7 is open, normal temperature tap water can flow into the second condenser 6 for heat exchange, and then enter the first condenser through the first three-way valve 10. Through double heat exchange, hot water above 65℃ can be produced to meet the demand of hot water above 65℃ in the hot spring hotel, metal processing, food and chemical industry and other industries. The embodiment can solve the problem that the conventional air energy heat pump system and the existing PVT heat pump system cannot produce hot water above 65℃.

[0041] The second electronic expansion valve 8 is arranged on the first branch and can control the refrigerant flow of the compressor 1 to the second condenser 6. When the opening degree of the second electronic expansion valve 8 is small, less refrigerant flows to the second condenser 6, and then the a-c conduction of the first three-way valve 10 can be set to allow part of the normal temperature tap water to directly flow to the first condenser.

[0042] The working process of the PVT heat pump system in heating (specifically, heating water) is as follows:

[0043] 1. The PVT heat pump system starts according to the preset start-up logic. When the system just enters the heating mode, the exhaust pressure P0 of the compressor is detected by a pressure sensor, and the outlet water temperature T1 of the first condenser is detected by a temperature sensor. If the exhaust pressure does not meet the preset pressure condition (P0≥P 预设 , P 预设 may be 3MPa), and the outlet water temperature does not meet the preset temperature condition (T1≥T 预设 , T 预设 may be 50℃), the electromagnetic valve is closed, the first three-way valve (two-in and one-out) is a-c conduction, the second three-way valve (one-in and two-out) is a-c conduction, the first electronic expansion valve is opened, and the second and third electronic expansion valves are fully closed.

[0044] It should be noted that when the system just starts and enters the heating mode, the exhaust pressure≥the preset pressure threshold and the outlet water temperature≥the preset temperature threshold are generally not immediately reached. Therefore, the above control operation can also be directly executed, that is, in the heating mode, the water and refrigerant of the PVT heat pump system are only exchanged through the first condenser, which specifically includes: controlling the electromagnetic valve to be closed, controlling the a port and the c port of the first three-way valve to be conduction, controlling the a port and the c port of the second three-way valve to be conduction, controlling the first electronic expansion valve to be opened, and controlling the second and third electronic expansion valves to be closed.

[0045] Based on the above control operation, water and refrigerant are exchanged by the first condenser, and the water temperature should not reach 50℃. The temperature difference between the refrigerant temperature at the outlet of the compressor and the water temperature is large, and the high-temperature and high-pressure refrigerant flows to the first condenser to achieve rapid heat exchange.

[0046] 2. Detect the exhaust pressure P0 of the compressor and the outlet water temperature T1 of the first condenser. If P0≥P and / or T1≥50℃, control the electromagnetic valve to open, the second electronic expansion valve to open, and the first three-way valve to switch to a-b conduction.

[0047] That is, after the exhaust pressure meets the preset pressure condition and / or the outlet water temperature meets the preset temperature condition, the water and refrigerant of the PVT heat pump system are controlled to exchange heat through the first condenser and the second condenser, specifically including: controlling the electromagnetic valve to open, controlling the second electronic expansion valve to open, and controlling the a port and the b port of the first three-way valve to conduct. Based on the above control operation, the high-temperature and high-pressure gaseous refrigerant at the outlet of the compressor is partially introduced to the second condenser for rapid heat exchange through the opening of the second electronic expansion valve, thereby preventing the outlet pressure of the compressor from further increasing and affecting the stability of the system, so as to further ensure that the water temperature can be heated to above 65℃. At the same time, the refrigerant introduced to the second condenser has higher heat exchange efficiency.

[0048] It should be noted that when the outlet water temperature of the second condenser reaches 50℃, the heat exchange efficiency of the refrigerant and the water will be greatly reduced, and the condensing temperature of the refrigerant coming out of the second condenser is relatively high, which reversely leads to high exhaust pressure of the compressor. When the exhaust pressure of the compressor exceeds the protection value, the system will stop, which is also the reason why the conventional air energy heat pump system can only heat water to 60℃.

[0049] 3. After entering the high-temperature hot water process, the opening degree of the second electronic expansion valve is a preset opening degree (the size of the preset opening degree is related to its model and can be adjusted). In order to ensure that the PVT heat pump system still has high COP performance when the water temperature is 50℃ or above, and to solve the problem of performance decline of the system when the water temperature reaches 50℃ or above, the embodiment proposes an optimal implementation manner, that is, the solar irradiance is monitored in real time by a solar irradiance meter. When the irradiance value exceeds a preset value (800w / m 2 ), the opening degree of the second electronic expansion valve is increased in proportion to the increase of the irradiance.

[0050] That is, after the water and refrigerant of the PVT heat pump system controlled by the first condenser and the second condenser are exchanged, the solar irradiance is detected, and the opening of the second electronic expansion valve is adjusted according to the irradiance. Specifically, after the irradiance exceeds the preset irradiance threshold, the opening of the second electronic expansion valve is increased according to the corresponding opening adjustment ratio of the change value of the irradiance. Thus, the PVT heat pump system can still have high COP performance when the water temperature is 50℃ or above.

[0051] While increasing the opening of the second electronic expansion valve, the safety of the compressor needs to be ensured, so the exhaust temperature of the compressor needs to be detected at the same time, and the exhaust temperature needs to be maintained within a preset safety range. If the exhaust temperature exceeds the preset safety range, the increase of the opening of the second electronic expansion valve is stopped.

[0052] It should be noted that when the exhaust temperature of the compressor is high, the exhaust pressure of the compressor will be high, and if the second electronic expansion valve is not opened, the pressure alarm of the compressor will be caused, so the second electronic expansion valve needs to be opened. When the irradiance is high, the PVT assembly generates a lot of heat, causing the suction temperature of the compressor to be high, which will cause the exhaust pressure to be higher, so the opening of the second electronic expansion valve needs to be further increased. In this way, the temperature of the first condenser can be reduced, and the exhaust pressure of the compressor can be reduced. When the opening of the second electronic expansion valve is small, the water quantity of the second condenser is small, and the a, b and c ports of the first three-way valve are connected; when the opening of the second electronic expansion valve is large, the water quantity of the second condenser is large, and the a and b ports of the first three-way valve are connected.

[0053] In addition, the PVT heat pump system of the embodiment further comprises a third electronic expansion valve 9 and a second three-way valve 11. The b port and the c port of the second three-way valve are both one-way valves. When the PVT heat pump system is defrosting, the system refrigerant undergoes phase change and absorbs heat through the PVT assembly (photovoltaic and photo-thermal assembly), and undergoes work through the compressor to generate high-temperature and high-pressure gaseous refrigerant. After the third electronic expansion valve is opened, part of the high-temperature and high-pressure gaseous refrigerant enters the finned heat exchanger. At this time, the finned heat exchanger functions as a condenser, and the high-temperature and high-pressure gaseous refrigerant releases heat in the finned heat exchanger, thereby achieving the effect of defrosting the finned heat exchanger. Another part of the high-temperature and high-pressure gaseous refrigerant exchanges heat with water through the first condenser to generate hot water. In this way, defrosting and hot water generation can be performed simultaneously in a low-temperature environment.

[0054] The PVT heat pump system further comprises: a pressure sensor 12 arranged at an exhaust port of the compressor 1 and capable of detecting the exhaust pressure of the compressor; a temperature sensor 13 arranged at a water outlet of the first condenser and capable of detecting the water outlet temperature of the first condenser; and an irradiance meter 14 arranged at the PVT assembly 5 and capable of detecting the solar irradiance. The above three parameters are key parameters for the PVT heat pump system to perform control operations in the hot water production process and the defrosting process. The problems that the existing air energy water heater cannot produce hot water during defrosting, affects the user experience, and increases the system energy consumption can be solved.

[0055] The working process of the PVT heat pump system during defrosting is as follows:

[0056] 1. The PVT heat pump system is started according to the preset defrosting mode. At this time, the electromagnetic valve is closed, the first three-way valve is in a-c conduction, the second three-way valve is in a-b conduction, the first electronic expansion valve and the second electronic expansion valve are closed, and the third electronic expansion valve is opened.

[0057] That is, the embodiment defrosts while producing heat, which is realized by the following control operations: controlling the electromagnetic valve to be closed, controlling the a port and the c port of the first three-way valve to be in conduction, controlling the a port and the b port of the second three-way valve to be in conduction, controlling the first electronic expansion valve and the second electronic expansion valve to be closed, and controlling the third electronic expansion valve to be opened.

[0058] Based on the above control operations, the system refrigerant undergoes phase change and absorbs heat through the PVT assembly (photovoltaic-thermal assembly), and undergoes work through the compressor to generate high-temperature and high-pressure gaseous refrigerant. Due to the opening of the third electronic expansion valve, part of the high-temperature and high-pressure gaseous refrigerant enters the finned heat exchanger. At this time, the finned heat exchanger functions as a condenser, and the high-temperature and high-pressure gaseous refrigerant releases heat in the finned heat exchanger, thereby achieving the effect of defrosting the finned heat exchanger. Another part of the high-temperature and high-pressure gaseous refrigerant exchanges heat with water through the first condenser to produce hot water. In this way, defrosting and hot water production can be performed simultaneously in a low-temperature environment.

[0059] 2. Adjusting the opening degree of the third electronic expansion valve according to the defrosting mode (fast defrosting mode, conventional defrosting mode).

[0060] That is, determining to perform the fast defrosting mode or the conventional defrosting mode according to the irradiance, and controlling the opening degree of the third electronic expansion valve in different defrosting modes, including:

[0061] If the irradiance < the preset value, it indicates that the current illumination is not strong enough, and the PVT assembly cannot obtain more heat, so only the conventional defrosting mode can be performed.

[0062] Performing the conventional defrosting mode, including: controlling the opening degree of the third electronic expansion valve to be k1.

[0063] If the irradiance ≥ preset value, it means that the light intensity is strong, and the PVT component can obtain more heat, and the fast defrosting mode can be selected to be executed, or the regular defrosting mode can be executed, that is, if k1 < k3 < k2, the fast defrosting mode or the regular defrosting mode is executed.

[0064] The fast defrosting mode or the regular defrosting mode is executed, including: if the fast defrosting mode is executed, the opening degree of the third electronic expansion valve is controlled to be k2; if the regular defrosting mode is executed, the opening degree of the third electronic expansion valve is controlled to be k3; wherein k1 < k3 < k2.

[0065] It should be noted that the larger the opening degree of the third electronic expansion valve is, the more high-temperature and high-pressure gaseous refrigerant flows to the finned heat exchanger, and the better and faster the defrosting effect is. Therefore, when the fast defrosting mode is executed, the opening degree of the third electronic expansion valve is controlled to be k2, and the value of k2 is set to be relatively high. When the regular defrosting mode is executed under the condition that the light intensity is not strong, the opening degree of the third electronic expansion valve cannot be set to be too large, because it is necessary to ensure that the heating water effect is ensured while defrosting, and it is necessary to ensure that when the light intensity is not strong, more high-temperature and high-pressure gaseous refrigerant passes through the first condenser to exchange heat with water to perform heating water. Therefore, the value of k1 is set to be relatively low.

[0066] The following will be described in detail:

[0067] After entering the defrosting mode, the irradiance E0 is first read, and compared with the preset value E (300 w / m 2 ), if E0 < E, the PVT heat pump system is not allowed to enter the fast defrosting mode. Specifically as follows:

[0068] 21) E0 ≥ E, two modes of regular defrosting and fast defrosting can be selected: the stronger the light intensity is, the more heat the PVT component obtains, and only then can the fast defrosting mode be executed.

[0069] In the regular defrosting mode:

[0070] The overall refrigerant flow rate flowing through the third electronic expansion valve (i.e. the flow rate flowing to the finned heat exchanger) accounts for about 1 / 3 of the total flow rate flowing through the compressor outlet, for example, for a 2.0C electronic expansion valve, the opening degree is about 200 steps.

[0071] In the fast defrosting mode:

[0072] The overall refrigerant flow rate flowing through the third electronic expansion valve accounts for about 1 / 2 of the total flow rate flowing through the compressor outlet, for example, for a 2.0C electronic expansion valve, the opening degree is about 350 steps.

[0073] 22) E0 < E, only the regular defrosting mode can be performed, and the overall refrigerant flow rate flowing through the third electronic expansion valve accounts for about 1 / 4 of the total flow rate flowing through the compressor outlet, for example, for a 2.0C electronic expansion valve, the opening degree is about 150 steps.

[0074] This embodiment proposes a PVT heat pump system for high-temperature high-efficiency heating and low-temperature high-efficiency defrosting, comprising a refrigerant system and a water system. The key components that differentiate this PVT heat pump system from existing systems are: a second electronic expansion valve 8, a third electronic expansion valve 9, a first electronic expansion valve 4, a first three-way valve 10, a second three-way valve 11, and a second condenser 6. Based on this new PVT heat pump system structure, it can produce high-temperature hot water at 65-70℃, meeting the needs of industries such as hot spring hotels, metal processing, food, and chemicals for hot water above 65℃. Furthermore, the system maintains high COP performance even at water temperatures of 50℃ and above. In addition, the new PVT heat pump system can heat while defrosting, requiring almost no additional mains power for defrosting, thus reducing users' electricity costs.

[0075] This embodiment also proposes a water heater that includes the PVT heat pump system described above. This water heater can produce high-temperature hot water at 65-70℃, meeting the needs of industries such as hot spring hotels, metal processing, food, and chemicals for hot water above 65℃.

[0076] In the above embodiments of this utility model, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0077] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0078] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0079] Furthermore, in the various embodiments of this utility model, the functional units can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0080] The device embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed to multiple network units. Part or all of the modules can be selected to achieve the purpose of the embodiment scheme according to actual needs.

[0081] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A PVT heat pump system, characterized by, The system comprises a compressor, a first condenser, a fin heat exchanger, a first electronic expansion valve connected in sequence, and a PVT assembly connected in parallel with the fin heat exchanger; the system further comprises: a second condenser arranged on a first branch, one end of the first branch being arranged on a pipeline between the compressor and the first condenser, and the other end being arranged on a pipeline between the first condenser and the fin heat exchanger; a solenoid valve arranged on a water inlet pipeline of the second condenser; a second electronic expansion valve arranged on the first branch and between the compressor and the second condenser; a third electronic expansion valve arranged on a second branch, one end of the second branch being arranged on a pipeline between the compressor and the first condenser, and the other end being arranged on a pipeline between the fin heat exchanger and the first electronic expansion valve; a first three-way valve, a port a of which is connected to the first condenser, a port b of which is connected to the second condenser, and a port c of which is connected to tap water; a second three-way valve arranged on a pipeline between the first condenser and the fin heat exchanger, a port a of which is connected to the fin heat exchanger, and ports b and c of which are connected to the first condenser.

2. The system of claim 1, wherein, The system further comprises: a pressure sensor arranged at an exhaust port of the compressor; a temperature sensor arranged at a water outlet of the first condenser; an irradiance meter arranged at the PVT assembly.

3. The system of claim 1, wherein, Ports b and c of the second three-way valve are both one-way valves.

4. A water heater, characterized by The water heater comprises the PVT heat pump system according to any one of claims 1 to 3.

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