Photovoltaic electric heat energy conversion and utilization device

Abstract

The invention discloses a photovoltaic electric heat energy conversion and utilization device, and relates to the field of application of a photovoltaic power generation technology to renewable energy heat utilization. Which comprises four control devices and is characterized in that the four control devices are divided into a series A, a series B, a series AB and a series C. The series A comprises an MC4 photovoltaic connector, a direct-current circuit breaker, an anti-reverse-connection diode, a surge protector, a direct-current metering unit, a mainboard, a control panel, a display panel and a wireless transmission unit. The important part of the A series is an integral structure, mainboard structure design, control logic and application of data in a wireless transmission platform. According to the invention, a switch control mode is adopted in a main circuit of the A-series-based control device, a mature power device with high cost performance is used, the circuit structure is simple, the control stability is enhanced, effective power control and good matching of device parameters are realized, the heat loss in electro-thermal conversion is improved, and relatively good electro-thermal conversion efficiency is obtained.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, and more specifically to a photovoltaic electrothermal energy conversion and utilization device. Background Technology

[0002] Currently, solar photovoltaic (PV) power generation technology is very mature, and most applications are mainly grid-connected power generation systems, stand-alone power generation systems, and battery energy storage systems. With the development of the photovoltaic and solar thermal industries, the application of electrothermal conversion systems has become very important. There are several applications and technologies for electrothermal conversion in solar PV power generation: First, for high-power PV arrays connected in series and parallel, inverters are used to convert the direct current (DC) PV power to alternating current (AC), and the electrothermal conversion is achieved through AC control devices and electric heaters. Second, for low-power power generation systems, DC contactors, solid-state relays, or power devices are directly connected to electric heaters to achieve electrothermal conversion. Third, centralized and decentralized PV hot water systems centralize the PV system, with electric heaters installed in decentralized water tanks. Electrothermal conversion is achieved through the linkage between centralized control and the water tank system control. Fourth, PV heat pump systems combine the PV power in series and parallel and connect it to a heat pump device. The device uses AC / DC complementarity to directly drive the heat pump, indirectly converting PV electricity into heat, thus achieving electrothermal conversion in this system. With the development of solar PV power generation electrothermal conversion systems, these four types of technologies and methods are applied in different scenarios. However, the existing technologies have the following problems:

[0003] Although the aforementioned existing equipment and technical methods are already in use, they all have shortcomings:

[0004] 1. In series-parallel high-power photovoltaic (PV) power generation array conversion applications, inverters are used to first convert DC to AC. Conventional heating control devices, such as electric heating or heat pump heating, are then employed to achieve electrothermal conversion. In some cases, batteries are also configured to ensure power stability. Inverters can achieve PV maximum power tracking. However, the DC-to-AC conversion incurs losses in the process of PV power generation and consumption due to conversion efficiency. When the converted AC power is used for heating, the instability of PV power generation leads to low electrothermal conversion efficiency. In addition, this implementation method has a high overall cost.

[0005] 2. In low-power power generation systems, DC contactors, solid-state relays, or power devices are generally used as switches to directly control the connection between photovoltaic power generation and electric heaters, achieving direct drive. However, this method is simple to control, lacks maximum power point tracking, has poor electrothermal conversion efficiency, and places high demands on the switching devices. In particular, if a solid-state relay or MOSFET power device fails and short-circuits, the heating system cannot be shut off, resulting in uncontrollable heating water temperature and creating safety hazards.

[0006] 3. Centralized and decentralized photovoltaic water heating systems are relatively advanced solar photovoltaic electrothermal conversion devices with maximum power point tracking (MPPT) capabilities, enabling efficient electrothermal conversion. However, these devices are suitable for specific scenarios, requiring centralized photovoltaic arrays and decentralized electrothermal conversion components of a certain quantity. Due to the linkage between centralized control and electrothermal conversion control, the overall system control device is also relatively complex.

[0007] 4. Photovoltaic heat pump systems are typical composite systems. Due to the integration of photovoltaic DC power and heat pump control circuits, the integration level is high. The control and power supply circuits of the heat pump system need to be designed separately, and it is not possible to quickly graft and apply standard heat pump products. Summary of the Invention

[0008] This invention provides a photovoltaic electrothermal energy conversion and utilization device to solve the problems mentioned in the background art.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0010] A photovoltaic electrothermal energy conversion and utilization device includes four control devices, which are divided into series A, series B, series AB and series C. The series A includes an MC4 photovoltaic connector, a DC circuit breaker, a reverse connection protection diode, a surge protector, a DC metering unit, a main board, a control board, a display board and a wireless transmission unit. The important parts of the series A are the overall structure, the main board structure design, the control logic and the application of data in the wireless transmission platform.

[0011] The B series uses the Boost or Buck basic circuit method;

[0012] The AB series is an A series control device with a B series conversion part embedded in it;

[0013] The C series is an extension based on the AB series or A series control devices.

[0014] A further improvement to the technical solution of this invention lies in the following: In the A series, the number of photovoltaic panel arrays connected in series is determined based on the voltage parameters of individual panels, and the number of parallel groups is determined based on the power. The positive and negative terminals of the array are connected to the control device, and the interface uses MC4 photovoltaic-specific connectors. When multiple groups are connected, the current needs to pass through anti-reverse connection diodes before being combined, and then enter the air circuit breaker. The air circuit breaker must be selected with parameters and model that meet the maximum power requirements of photovoltaic power generation. The lower end of the air circuit breaker is connected to the main board, which distributes power to the load heating element. This is the entire main circuit, which is DC without any form of power conversion. In the main board, combined with the load power distribution, the maximum voltage of a single circuit can meet DC 450V, and the current can meet 1 For 0A output, 250V / 8A is selected in general configuration parameters. This parameter is a key consideration for the control device motherboard. Furthermore, the single motherboard design is laid out with 6 channels, as shown in the main circuit diagram. The number of groupings (6) is also a key consideration for the control device motherboard. Based on the heat dissipation characteristics of the power devices, the optimal spacing and distribution are given in the motherboard. The motherboard uses MOSFETs, and the drive circuit is a single-phase power supply with isolated drive mode. Heat dissipation devices are configured according to the heat dissipation performance of the MOSFETs. In short, the research and design of the control device motherboard is one of the main aspects of this method. The control board uses a microprocessor as the core unit, which collects the DC parameters of the main input terminal, including voltage, current, and power, and tracks the instantaneous power Q of photovoltaic power generation. pv , and heating element power q i Matching, controlling the number of MOSFETs on and off, n, to satisfy the following formula:

[0015] A further improvement to the technical solution of this invention lies in the following: In the A series, the corresponding quantity n is found according to the quantity matching method, and the optimal values ​​of n and n+1 are determined according to the power change trend. The control board is connected to the display board, which displays the basic parameters and the settings of key parameters in the system, as well as the basic button content. A transmission unit for a remote platform is added to the device. The irradiance data collected on the platform directly reflects the power generation trend of the photovoltaic array. The relative data relationship between power generation and solar irradiance provides a basis for calibration of the control logic, ensuring that the entire control device can achieve the overall efficiency of photoelectric conversion and guarantee the system conversion efficiency R. he W pv U max Ideally, the maximum power tracking curve of the control device can be used to establish a relationship with photovoltaic irradiance data. In scenarios where photovoltaic irradiance data is required, the maximum power value can be equivalently multiplied by a coefficient to represent and adopt the data.

[0016] A further improvement to the technical solution of this invention lies in the following: In the B series, for low-power photovoltaic power generation systems, Boost conversion is used for photovoltaic hot water systems with photovoltaic arrays of 400-1500W. The photovoltaic modules in the photovoltaic array are connected in single or parallel groups. The control device has a single photovoltaic DC input, and the output corresponds to one group of electric heating. The control system collects the current DC parameters, including voltage, current, and power. Based on the maximum power, the output power is matched by adjusting the voltage or current of the conversion circuit to achieve linear power matching. Similarly, Buck conversion is used for systems of 1500-3000W. In this photovoltaic array, 3-6 photovoltaic modules are connected in series. The control device has a single photovoltaic DC input and an output corresponding to a set of electric heating elements. The control system collects current DC parameters, including voltage, current, and power. Based on the maximum power, it adjusts the voltage or current of the conversion circuit to match the output power, achieving linear power matching. The B-series control device needs to consider the series and parallel connection of the photovoltaic modules, generally divided into single-module, parallel double-module, and 3-6-module series connections. In the control device, whether it is a Boost or Buck conversion, it is based on the maximum output voltage U. max and photovoltaic array power W pv Determine the heating element R he The parameters,

[0017] A further improvement to the technical solution of this invention lies in the following: To compensate for the matching error between photovoltaic power generation and matched output power in the A-series control device, the AB series can introduce the core conversion section from the B-series. In the n output paths of the A-series control device, the nth path is selected as the conversion loop, and the power of this path is q. n The other n-1 channels are A-series control loops, each with a power of q. i In actual operation, the matching power is q. z The AB series control device realizes the linear matching relationship in the high-power photothermal conversion system, and the equivalent expression is as follows:

[0018] A further improvement to the technical solution of this invention lies in the following: The C-series extension has two forms. One is to link the total DC power or part of the DC power after the current is combined with the standard photovoltaic conversion equipment of the inverter through a double-break switch. While ensuring that the photovoltaic-thermal conversion system meets the demand, the instantaneous power generation can be used for other standard electrical equipment. The other is to introduce AC power into the control device. Since photovoltaic power generation is affected by solar radiation, there is intermittent power generation. In order to ensure the continuity of the demand for electricity, AC power can be reasonably used as a supplement through control strategies. Commonly used equipment are AC electric heaters and heat pumps. In the photovoltaic + heat pump system, not only can photovoltaic DC and mains AC be used to complement each other, but photovoltaic electric thermal conversion can also be used as a secondary heating booster for the system.

[0019] Due to the adoption of the above technical solution, the technical progress achieved by this invention compared to the prior art is as follows:

[0020] 1. This invention provides a photovoltaic electrothermal energy conversion and utilization device. By adopting a switch control method in the main circuit of the A-series control device, using cost-effective and mature power devices, the circuit structure is simple, enhancing the stability of control, and achieving effective power control and good matching of device parameters. This improves the heat loss in electrothermal conversion and achieves better electrothermal conversion efficiency.

[0021] 2. This invention provides a photovoltaic electrothermal energy conversion and utilization device. Although the B-series conversion circuit has increased the complexity of the conversion circuit compared to the A-series main circuit, it is more complex than inverters and other power conversion equipment. It not only solves the shortcomings of such equipment in electrothermal conversion, but also reduces costs and improves the overall cost performance. In order to better meet the transient linear performance of electrothermal conversion and further improve the conversion efficiency, the design concept of AB-series control device is proposed.

[0022] 3. This invention provides a photovoltaic electrothermal energy conversion and utilization device. The C series not only considers the performance of the control device itself, but also provides complementary control methods and strategies for photovoltaic power generation electrothermal conversion and other heating equipment from the perspective of system application, so as to meet the comprehensive needs of heat and electricity in multiple application scenarios.

[0023] 4. This invention provides a photovoltaic electrothermal energy conversion and utilization device. Each series of control devices is applicable to photovoltaic power generation hot water systems, photovoltaic power generation heating systems, and photovoltaic power generation hot water systems. It also considers other systems based on the high-efficiency electrothermal conversion method of solar photovoltaic power generation. It can be connected to non-electrothermal conversion equipment such as general inverters, grid-connected inverters, and off-grid inverters. Therefore, it can be extended to auxiliary systems containing mains heating, phase change heat storage, heat pumps, and air conditioning. The entire series of control devices is easy to operate and considers linkage with Internet of Things systems to realize basic functions such as remote control, data analysis, and feedback control. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the A-series structure of the present invention;

[0025] Figure 2 This is a schematic diagram of the B-series structure of the present invention;

[0026] Figure 3 This is a schematic diagram of the AB series structure of the present invention;

[0027] Figure 4 This is a schematic diagram of the C-series structure of the present invention;

[0028] Figure 5 This is a schematic diagram of the main circuit of the motherboard of the present invention;

[0029] Figure 6 This is a schematic diagram of the heating element of the present invention;

[0030] Figure 7 This is a simplified diagram of the Boost converter circuit of the present invention;

[0031] Figure 8 This is a simplified diagram of the Buck converter circuit of the present invention. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to embodiments:

[0033] Example 1

[0034] like Figure 1-8 As shown, the present invention provides a photovoltaic electrothermal energy conversion and utilization device, including four control devices, which are divided into series A, series B, series AB and series C. Series A includes an MC4 photovoltaic connector, a DC circuit breaker, a reverse connection protection diode, a surge protector, a DC metering unit, a main board, a control board, a display board and a wireless transmission unit. The important parts of series A are the overall structure, the main board structure design, the control logic and the application of data in the wireless transmission platform.

[0035] The B series uses the Boost or Buck basic circuit design.

[0036] The AB series is an A series control device with the B series conversion part embedded inside;

[0037] The C series is an extension based on the AB series or A series control devices.

[0038] Example 2

[0039] like Figure 1-8As shown, based on Embodiment 1, this invention provides a technical solution: Preferably, in the A series, the number of photovoltaic panel arrays connected in series is determined according to the voltage parameters of individual panels, and the number of parallel groups is determined according to the power. The positive and negative terminals of the array are connected to the control device, and the interface uses MC4 photovoltaic-specific connectors. When multiple groups are connected, they need to pass through anti-reverse connection diodes before being combined, and then enter the air circuit breaker. The air circuit breaker must be selected with parameters and model that meet the maximum power requirements of photovoltaic power generation. The lower end of the air circuit breaker is connected to the main board, which distributes power to the load heating element. This is the entire main circuit, which is DC without any form of power conversion. In the main board, combined with the load power distribution, the maximum voltage of a single circuit is given to be DC450V. The current can meet 10A output. In general configuration parameters, 250V / 8A is selected. This parameter is a key consideration for the control device motherboard. In addition, the single motherboard design is laid out with 6 channels, as shown in the main circuit diagram of the motherboard. The number of groups of 6 is also a key consideration for the control device motherboard. According to the heat dissipation characteristics of power devices, the optimal spacing and distribution are given in the motherboard. MOSFETs are used in the motherboard, and the drive circuit is a single-phase power supply isolated drive method. Heat dissipation devices are configured according to the heat dissipation performance of MOSFETs. In short, the research and design of the control device motherboard is one of the main aspects of this method. The control board uses a microprocessor as the core unit. It collects the DC parameters of the main input terminal, including voltage, current, and power, and tracks the instantaneous power Q of photovoltaic power generation. pv , and heating element power q i Matching, controlling the number of MOSFETs on and off, n, to satisfy the following formula: In Series A, the corresponding quantity n is found using a quantity matching method. Based on the power change trend, the optimal values ​​of n and n+1 are determined. The control board is connected to the display board, which displays basic parameters, settings for key system parameters, and basic button functions. A remote platform transmission unit is added to the device. The irradiance data collected on the platform directly reflects the photovoltaic array's power generation trend. The relative relationship between power generation and solar irradiance provides a basis for calibrating the control logic, ensuring the entire control device can achieve the overall efficiency of photoelectric conversion and guaranteeing the system conversion efficiency R. he W pv U max Ideally, the maximum power tracking curve of the control device can be used to establish a relationship with photovoltaic irradiance data. In scenarios where photovoltaic irradiance data is required, the maximum power value can be equivalently multiplied by a coefficient to represent and adopt the data.

[0040] In this embodiment, the A-series method, in the specific implementation of the control device, needs to consider the specific arrangement of the photovoltaic array in the system, and also the power of the load heating element. Combined with the actual heat load requirements, the structure and corresponding specific power value of the load heating element are designed, generally expressed by the resistance value under the withstand voltage condition. After the total load power value is determined, the system cost-effectiveness must be considered. The rated power of photovoltaic power generation is determined based on being greater than or equal to the load power. Due to the parameters of the photovoltaic power generation components, the rated power and the number of series and parallel connections must be met to determine the actual rated total power of the photovoltaic array. Generally, parallel connections are grouped together and connected to the control device. Considering factors such as cable cost and wiring space, the total number of input groups introduced into the control device is determined. Each input group is connected to the control device through an MC4 DC dedicated connector. The heating element configured in the A-series control device is generally divided into 3 U-type units, with 3 positive terminals and 1 common negative terminal. In the control device, the mainboard standard module can connect two groups of heating elements, corresponding to 6 U-type units. When selecting the electrical parameters of each U-type unit, the DC withstand voltage range of 250V-450V is generally the primary consideration. Power matching is calculated based on the total series voltage of the actual photovoltaic array. Due to the limitation of the output current of the control device, it generally does not exceed 10A. In actual applications, adjustments can be made according to specific circumstances. In specific implementation, the power or resistance value of the heating element and each U of the heating element can be determined based on comprehensive parameters such as the series voltage of the photovoltaic array, the electrical parameters output by the main board, and the total power. The heating element connected to the control device has overload protection control. The control circuit of the control device realizes the power matching between the photovoltaic array power and the load heating element. During operation, the load power changes automatically with the instantaneous power of the photovoltaic array. The control device collects the temperature of the heat storage device corresponding to the heating element, which is generally an insulated water tank or a thermal storage boiler. Through the heat storage temperature, the drive switch in the electrothermal conversion is automatically controlled to achieve the purpose of on-demand conversion. In order to meet the time of electrothermal conversion, control strategies for different temperature conditions are adopted. The operating data is connected to the Internet of Things platform to realize data recording, remote viewing and control, etc. The operating data of the control device includes: total photovoltaic power generation, voltage, current, power, heat storage device temperature, ambient temperature, photovoltaic backsheet temperature, water tank temperature, irradiance, etc.

[0041] Example 3

[0042] like Figure 1-8As shown, based on Embodiment 1, the present invention provides a technical solution: Preferably, in the B series, in a low-power photovoltaic power generation system, for a photovoltaic hot water system with a photovoltaic array of 400-1500W, Boost conversion is used. The photovoltaic modules in the photovoltaic array are connected in single or double parallel groups. The control device has a single photovoltaic DC input, and the output corresponds to one group of electric heating. The control system collects the current DC parameters, including voltage, current, and power. Based on the maximum power, the output power is matched by adjusting the voltage or current of the conversion circuit to achieve linear power matching. Similarly, for a system of 1500-3000W, Boost conversion is used. Using Buck converters, the photovoltaic array uses 3-6 photovoltaic modules in series. The control device has a single photovoltaic DC input and an output corresponding to a set of electric heating elements. The control system collects current DC parameters, including voltage, current, and power. Based on the maximum power, it adjusts the voltage or current of the conversion circuit to match the output power, achieving linear power matching. B-series control devices need to consider the series and parallel connection configuration of the photovoltaic modules, generally categorized as single-module, parallel dual-module, and 3-6 module series connections. In the control device, regardless of whether it's a Boost or Buck conversion, it's based on the maximum output voltage U. max and photovoltaic array power W pv Determine the heating element R he The parameters,

[0043] In this embodiment, the B-series method is implemented in the control device. In single-module and dual-module series systems, the Boost conversion method is used, as shown in the figure. The rated voltage of the module is generally 35-50V DC, and the corresponding boost output is 50-110V. When 3-5 modules are connected in series, the Buck conversion method is used, as shown in the figure. The rated voltage of the module is generally 110V-450V DC. Both conversion methods determine the heating element resistance value based on the photovoltaic module parameters. The control device is equipped with an MC4 connector, using the photovoltaic array as the input of the control device and the heating element as the output of the control device. The device has built-in input and output voltage and current acquisition, and is linked with the control part through the RS485 interface to realize the start or end of the conversion under the control logic conditions.

[0044] Example 4

[0045] like Figure 1-8 As shown, based on Embodiment 1, the present invention provides a technical solution: Preferably, in order to compensate for the matching error between the photovoltaic power generation and the matched output power in the A-series control device, the core conversion part of the B-series can be introduced. In the n output paths of the A-series control device, the nth path is selected as the conversion loop, and the power of this path is q. n The other n-1 channels are A-series control loops, each with a power of q. iIn actual operation, the matching power is q. z The AB series control device realizes the linear matching relationship in the high-power photothermal conversion system, and the equivalent expression is as follows:

[0046]

[0047] In this embodiment, the specific implementation of the AB series control device combines the A series conversion part and is basically the same as the implementation process of the A series. The main difference is that a special U is added. This output is also specially marked in the control device, which is an important manifestation that distinguishes it from other Us. The internal control adopts the B series conversion. The parameters of the special U are also different from the design of other Us. The data acquisition of other sensors is similar to the implementation of the A series control device.

[0048] Example 5

[0049] like Figure 1-8 As shown, based on Embodiment 1, the present invention provides a technical solution: Preferably, there are two extension forms of the C series. One is to link the total DC power or part of the DC power after the combined power supply with the standard photovoltaic conversion equipment of the inverter through a double-break switch. While ensuring that the photovoltaic thermal conversion system meets the requirements, the instantaneous power generation can be used for other standard electrical equipment. The other is to introduce AC power into the control device. Since photovoltaic power generation is affected by solar radiation, there is intermittent power generation. In order to ensure the continuity of the demand for electricity, AC power can be reasonably used as a supplement through control strategies. Commonly used equipment are AC electric heaters and heat pumps. In the photovoltaic + heat pump system, not only can photovoltaic DC and mains AC complement each other, but photovoltaic electric thermal conversion can also be used as a secondary heating booster of the system.

[0050] In this embodiment, the C-series control device is an extension based on the AB-series or A-series control devices. Extension one involves controlling the main photovoltaic DC circuit externally, requiring switching to a built-in or external inverter for direct use to meet external power demands. Internally, it employs a DC relay device of a certain capacity. When the switching power is large, it can control the power supply of each main board in the device in groups, simultaneously controlling the external power supply at the inverter output. This allows the control device to achieve electrothermal conversion under certain control strategies while simultaneously meeting the immediate external power supply needs of photovoltaic power generation. Extension two involves the control device itself being able to connect to AC power according to actual power requirements. Internally, the control device complements the photovoltaic DC power supply. By combining with inverters that have complementary functions, it can power equipment such as heat pumps and air conditioners. Furthermore, in the overall system design, direct photovoltaic heating can be used as the main guarantee for secondary temperature improvement, compensating for the temperature rise of the equipment itself and improving the overall utilization of the system. Data acquisition from other sensors is similar to that of the A-series control device.

[0051] The working principle of this photovoltaic electrothermal energy conversion and utilization device will be explained in detail below.

[0052] like Figure 1-8 As shown, firstly, in high-power systems, following the heating element manufacturing process, one U of the electric heating element is used as a group of heating units, with 3 Us forming one electric heating element. By configuring no less than 2 electric heating elements, i.e., 6 Us, and in low-power systems, one electric heating element, i.e., 3 Us, can be used to dynamically match the equivalent resistance of the photovoltaic array, achieving maximum power electrothermal conversion. In practical applications, it is not limited to 3 or 6 Us, and is suitable for various situations that can meet the maximum conversion efficiency. Furthermore, in low-power high-voltage or low-voltage photovoltaic power generation applications, Boost conversion and Buck conversion circuits are used respectively to achieve matching between the load power and the current power of the photovoltaic array, achieving maximum power electrothermal conversion. Secondly, the combination of the above two methods can be used more precisely in high-power photovoltaic power generation electrothermal conversion applications. In loads of no less than 6 Us, the following methods are employed... A special unit (U) is used, employing either Boost or Buck conversion. Five units (U) are used for switch control. By utilizing the combination of five switches and one linear unit, linear adjustment within the total power range can be achieved, matching the equivalent load with the instantaneous maximum power of the photovoltaic array. This ultimately achieves efficient electrothermal conversion at maximum power. Furthermore, in combination with other auxiliary equipment, it can compensate for shortcomings in applications. In the combination of photovoltaics and heat pumps, the extended application of this method not only solves the problem of photovoltaic power generation achieving electrothermal conversion through heat pumps but also realizes the application of heat storage and high-temperature water through the water tank in the system. Therefore, this invention essentially provides a general method for electrothermal applications based on solar photovoltaic power generation, possessing applicability in many situations. At the same time, it also supports the combination with renewable energy equipment such as heat pumps, promoting the comprehensive development of photovoltaic multi-energy complementary systems.

[0053] The present invention has been described in detail above. However, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, any modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A photovoltaic electrothermal energy conversion and utilization device, comprising four control devices, characterized in that: The four control devices are divided into series A, series B, series AB and series C. Series A includes MC4 photovoltaic connector, DC circuit breaker, reverse connection protection diode, surge protector, DC metering unit, motherboard, control board, display board and wireless transmission unit. The important parts of series A are the overall structure, motherboard structure design, control logic and data application in the wireless transmission platform. The B series uses the Boost or Buck basic circuit method; The AB series is an A series control device with a B series conversion part embedded in it; The C series is an extension based on the AB series or A series control devices.

2. The photovoltaic electrothermal energy conversion and utilization device according to claim 1, characterized in that: In the A-series photovoltaic panel array, the number of panels connected in series is determined based on the voltage parameters of each panel, and the number of parallel groups is determined based on the power output. The positive and negative terminals of the array are connected to the control device, and the interface uses MC4 photovoltaic-specific connectors. When multiple groups are connected, the current must first pass through anti-reverse connection diodes before being combined, and then enter the air circuit breaker. The air circuit breaker must be selected with parameters and model that meet the maximum power requirements of photovoltaic power generation. The lower end of the air circuit breaker is connected to the main board, which distributes power to the load heating element. This is the entire main circuit, which is DC without any form of power conversion. In the main board, combined with the load power distribution, the maximum voltage of a single circuit can meet DC 450V, and the current can meet 10A output. In general configuration parameters, 250V / 8A is selected. This parameter is a key consideration for the control device motherboard. Furthermore, the single motherboard design is laid out in 6-channel configurations, as shown in the main circuit diagram. The number of groupings (6) is also a key consideration for the control device motherboard. Based on the heat dissipation characteristics of the power devices, the optimal spacing and distribution are given in the motherboard. The motherboard uses MOSFETs, and the drive circuit is an independently powered, isolated drive method. Heat dissipation devices are configured according to the heat dissipation performance of the MOSFETs. In short, the research and design of the control device motherboard is one of the main aspects of this method. The control board uses a microprocessor as its core unit, which collects the DC parameters of the main input terminals, including voltage, current, and power, and tracks the instantaneous power of photovoltaic power generation. With heating element power Matching, controlling the number of MOSFETs on and off, n, to satisfy the following formula:

3. The photovoltaic electrothermal energy conversion and utilization device according to claim 2, characterized in that: In the A series, the corresponding quantity n is found according to the quantity matching method. Based on the power change trend, the optimal values ​​of n and n+1 are determined. The control board is connected to the display board, which displays the basic parameters and the settings of key parameters in the system, as well as the basic button content. A remote platform transmission unit is added to the device. The irradiance data collected on the platform directly reflects the power generation trend of the photovoltaic array. The relative data relationship between power generation and solar irradiance provides a basis for calibration of the control logic, ensuring that the entire control device can achieve the overall efficiency of photoelectric conversion and guarantee the optimal system conversion efficiency. In addition, the maximum power tracking curve of the control device can also be used to establish a relationship with the photovoltaic irradiance data. In scenarios where photovoltaic irradiance data is required, the maximum power value is equivalently multiplied by a coefficient to represent and adopt the data.

4. The photovoltaic electrothermal energy conversion and utilization device according to claim 1, characterized in that: The B-series control system employs Boost conversion for photovoltaic hot water systems with a photovoltaic array of less than 1000W. The photovoltaic modules in the array are connected in single or parallel groups. The control device uses a single-channel DC input for the photovoltaic array, with the output corresponding to one set of electric heaters. The control system collects current DC parameters, including voltage, current, and power. Based on the maximum power, it adjusts the voltage or current of the conversion circuit to match the output power, achieving linear power matching. Similarly, for systems of 1000-3000W, Buck conversion is used. The photovoltaic modules in the array are connected in series in groups of 2-5. The control device uses a single-channel DC input for the photovoltaic array, with the output corresponding to one set of electric heaters. The control system collects current DC parameters, including voltage, current, and power. Based on the maximum power, it adjusts the voltage or current of the conversion circuit to match the output power, achieving linear power matching. The B-series control device needs to consider the series and parallel connection of the photovoltaic modules, generally categorized as single module, parallel dual modules, or 2-5 modules in series. In the control device, regardless of whether Boost or Buck conversion is used, the maximum output voltage is used as the basis for the conversion. and photovoltaic array power Determine the heating element The parameters are such that the following formula is satisfied:

5. The photovoltaic electrothermal energy conversion and utilization device according to claim 1, characterized in that: To compensate for the matching error between photovoltaic power generation and matched output power in the A-series control device, the AB series can incorporate the core conversion section from the B-series. From the n output paths of the A-series control device, the nth path is selected as the conversion loop, and the power of this path is... The other n-1 channels are A-series control loops, and the power of each channel is... In actual operation, the matching power is: The AB series control device realizes the linear matching relationship in the high-power photothermal conversion system, and the equivalent expression is as follows:

6. The photovoltaic electrothermal energy conversion and utilization device according to claim 1, characterized in that: The C-series extension has two forms. One is to link the total DC power or part of the DC power after the combined power supply with photovoltaic conversion equipment such as inverters through a double-break switch. While ensuring that the photovoltaic-thermal conversion system meets the demand, the instantaneous power generation can be used for other standard electrical equipment. The other is to introduce AC power into the control device. Since photovoltaic power generation is affected by solar radiation, there is an intermittent power generation. In order to ensure the continuity of the demand for electricity, AC power can be used to supplement it rationally through control strategies. Commonly used equipment are AC electric heaters and heat pumps. In the photovoltaic + heat pump system, not only can photovoltaic DC and mains AC power be used to complement each other, but photovoltaic electrothermal conversion can also be used as a secondary heating booster for the system.

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