Photovoltaic junction box and photovoltaic panel control system

Abstract

The embodiment of the invention discloses a photovoltaic junction box and a photovoltaic panel control system, a positive electrode interface and a negative electrode interface are arranged in the photovoltaic junction box and are respectively connected with the positive electrode and the negative electrode of a photovoltaic panel, the positive electrode and the negative electrode of the photovoltaic panel are both connected with a power line, and a bypass circuit is arranged between the positive electrode interface and the negative electrode interface. And arranging a power line communication circuit between the positive interface and the negative interface to realize data communication according to a power line. Therefore, the communication of the photovoltaic panel is realized under the condition of not arranging an additional device, and the cost of the photovoltaic panel control system is reduced.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation, and more particularly to a photovoltaic junction box and photovoltaic panel control system. Background Technology

[0002] In photovoltaic communication systems, photovoltaic panels are typically controlled via photovoltaic junction boxes. Specifically, photovoltaic panels are the power generation source, used to convert solar energy into direct current (DC) power, while photovoltaic junction boxes are the power management and output interfaces for the photovoltaic panels. They are responsible for safely exporting and optimizing the transmission of the power generated by the photovoltaic panels, and protecting the photovoltaic panels from damage caused by overcurrent, reverse charging, and other risks.

[0003] Existing photovoltaic (PV) junction boxes primarily consist of bypass diodes to bypass PV panels when they malfunction, thus preventing interference with other PV panels. They typically lack communication functionality. While PV shutdown devices and PV optimizers offer communication capabilities, they are relatively expensive. For example, PV optimizers require inductors to store power line carrier communication signals; however, inductors are costly and generate significant heat, hindering cost savings.

[0004] Therefore, there is a need for a solution to control photovoltaic panels that can enable communication with the panels at a lower cost. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a photovoltaic junction box and a photovoltaic panel control system, which can realize the communication of the photovoltaic panel without the need to install an inductor, thereby reducing the cost of the photovoltaic panel control system.

[0006] In a first aspect, embodiments of the present invention provide a photovoltaic junction box, the photovoltaic junction box comprising: A positive terminal interface is used to connect to the positive terminal of a photovoltaic panel, which is connected to a power line. The negative terminal interface is used to connect to the negative terminal of the photovoltaic panel, which is connected to the power line. The bypass circuit is connected between the positive and negative terminals of the photovoltaic junction box. A power line communication circuit, connecting the positive and negative interfaces, is used for data communication via the power line.

[0007] In some embodiments, the power line communication circuit includes: The carrier transceiver circuit includes a positive terminal and a negative terminal. A matching circuit, disposed between the positive and negative interfaces and connected to the carrier transceiver circuit, is used to obtain a carrier signal from the power line and send it to the carrier transceiver circuit, or to obtain a carrier signal from the carrier transceiver circuit and send it to the power line.

[0008] In some embodiments, the bypass circuit includes a switching transistor and a controller; The controller is used to control the switch to turn on when the voltage at the positive terminal is less than that at the negative terminal, and to control the switch to turn off when the voltage at the positive terminal is greater than or equal to that at the negative terminal.

[0009] In some embodiments, the photovoltaic panel is further provided with a first junction box and a second junction box. The first junction box is used to connect to the positive electrode of the photovoltaic panel, and the second junction box is used to connect to the negative electrode of the photovoltaic panel. The photovoltaic junction box is connected between the first junction box and the second junction box.

[0010] In some embodiments, the positive terminal of the photovoltaic junction box is connected to the negative terminal of the first junction box, and the photovoltaic junction box is connected to the positive terminal of the second junction box.

[0011] In some embodiments, the positive terminal of the photovoltaic junction box is connected to the positive terminal of the first junction box, and the negative terminal of the photovoltaic junction box is connected to the negative terminal of the second junction box.

[0012] In some embodiments, the photovoltaic junction box further includes: The detection module is used to detect at least one of the following: voltage, temperature, and light intensity of the photovoltaic panel.

[0013] In some embodiments, the photovoltaic junction box further includes: A voltage acquisition circuit is connected between the first and second interfaces to measure the voltage between the two interfaces.

[0014] In some embodiments, the first interface is the positive terminal interface of the photovoltaic junction box and the second interface is the negative terminal interface of the photovoltaic junction box; or The first interface is the positive terminal of the first junction box, and the second interface is the positive terminal of the photovoltaic junction box; or The first interface is the negative terminal of the photovoltaic junction box, and the second interface is the negative terminal of the second junction box.

[0015] Secondly, embodiments of the present invention provide a photovoltaic panel control system, the system comprising: Photovoltaic panels; At least one photovoltaic junction box as described in the first aspect is disposed on the photovoltaic panel.

[0016] The technical solution of this invention provides a photovoltaic junction box with a positive and a negative interface for connecting the positive and negative terminals of the photovoltaic panel, respectively. Both the positive and negative terminals of the photovoltaic panel are connected to power lines. A bypass circuit is provided between the positive and negative interfaces, and a power line communication circuit is also provided between the positive and negative interfaces to achieve data communication via the power lines. Therefore, communication of the photovoltaic panel is achieved without the need for additional components, reducing the cost of the photovoltaic panel control system. Attached Figure Description

[0017] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which: Figure 1 This is a schematic diagram of a photovoltaic control system in the prior art; Figure 2 This is a schematic diagram of a photovoltaic system according to an embodiment of the present invention; Figure 3 This is a circuit diagram of a photovoltaic junction box according to an embodiment of the present invention; Figure 4 This is a circuit diagram of the bypass circuit according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a photovoltaic control system according to an embodiment of the present invention; Figure 6 This is a schematic diagram of a photovoltaic control system according to another embodiment of the present invention. Detailed Implementation

[0018] The present application is described below based on embodiments, but it is not limited to these embodiments. In the detailed description of the present application below, certain specific details are described in detail. Those skilled in the art can fully understand the present application without these details. To avoid obscuring the substance of the present application, well-known methods, processes, flows, elements, and circuits are not described in detail.

[0019] Furthermore, those skilled in the art should understand that the accompanying drawings provided herein are for illustrative purposes only and are not necessarily drawn to scale.

[0020] Furthermore, it should be understood that in the following description, "circuit" refers to a conductive loop consisting of at least one element or sub-circuit connected by electrical or electromagnetic connections. When an element or circuit is said to be "connected" to another element or "connected" between two nodes, it can be directly coupled or connected to another element, or there may be intermediate elements. The connection between elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected" to another element, it means that there are no intermediate elements between them.

[0021] Unless the context explicitly requires it, words such as "including" or "contains" throughout the application should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to".

[0022] In the description of this application, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0023] Photovoltaic (PV) power generation systems are clean energy systems that directly convert solar radiation into electricity using semiconductors, achieving efficient conversion from solar energy to usable electricity. They are widely used in centralized power plants, distributed rooftop power generation, and other scenarios. A PV system comprises multiple photovoltaic strings, each containing multiple photovoltaic panels connected in series for power generation. These panels are made of monocrystalline silicon, polycrystalline silicon, or other types of solar cells encapsulated in series, absorbing sunlight and generating direct current (DC). Generally, each photovoltaic panel includes a matching junction box, which discharges electricity through internal conductive terminals while using bypass diodes to prevent hot spot effects and protect the panel. Due to their clean and pollution-free operation, low maintenance costs, modularity, and scalability, PV systems can provide large-scale power to large power plants as well as power distributed applications in homes and businesses, making them a crucial force in driving energy structure transformation.

[0024] In photovoltaic (PV) power generation systems, PV panels and PV junction boxes are functionally deeply integrated and physically tightly coupled collaborative units. As the power source, the PV panel consists of multiple PV cells connected in series or parallel via solder ribbons to form a circuit, converging into internal positive and negative electrodes within the module's backsheet. Therefore, it cannot directly connect to external cables and must rely on the PV junction box for an interface. Specifically, the junction box directly solders or crimps its internal conductive terminals to the positive and negative electrodes of the PV module, and then uses its own positive and negative taps to lead out the DC power generated by the module, thus transmitting the electrical energy to downstream equipment. Furthermore, the safe operation of the PV module highly depends on the protective functions of the PV junction box. Specifically, when the PV panel is operating, problems such as partial shading or cell aging can easily trigger hot spot effects. The bypass circuit built into the junction box is connected in series and parallel with the cells inside the module. When a string of cells generates power abnormally, the bypass circuit activates the bypass loop, allowing the current to bypass the faulty area. Furthermore, at night or when the module is not generating electricity, the current from the external circuit may flow into the module in reverse. In this case, the bypass circuit can block the reverse current, thereby preventing the battery cells from being damaged by reverse charging.

[0025] Current photovoltaic (PV) junction boxes generally lack communication capabilities, making it impossible to detect and control the status of PV panels. To achieve communication functionality, PV shutdown devices and PV optimizers are typically used. PV shutdown devices can quickly cut off the DC power output of PV modules or strings in specific scenarios. Specifically, in maintenance scenarios, maintenance personnel can activate the PV shutdown device via remote commands, local buttons, or infrared triggers to reduce the output voltage of the modules in the maintenance area to a safe range, thus preventing electric shock accidents. Furthermore, when the system detects faults or dangerous situations such as module short circuits, cable damage, or fires, the PV shutdown device can automatically respond to protection signals and quickly cut off the power transmission link, preventing the fault from spreading to other modules or downstream equipment. PV optimizers can solve the problem of power generation loss in PV arrays caused by changes in the external environment. Specifically, when there is uneven light intensity or inconsistent parameters among PV panels, the PV optimizer connects to the PV panels to adjust the operating voltage and current of the modules in real time, ensuring that each module operates at its maximum power operating point. In addition, the photovoltaic optimizer also has data acquisition and fault diagnosis functions, which collect the power generation data, voltage and current parameters of the modules in real time and upload them to the testing platform to help maintenance personnel accurately identify the causes of module inefficiency such as shading, aging, and faults, so as to facilitate targeted maintenance.

[0026] However, photovoltaic (PV) shut-off devices and PV optimizers are relatively expensive. When a PV power generation system includes a large number of PV panels, installing a PV shut-off device or PV optimizer for each PV panel would significantly increase the cost of the PV power generation system.

[0027] Figure 1 This is a schematic diagram of a photovoltaic control system in the prior art, such as... Figure 1 As shown, the photovoltaic panel control system realizes power line carrier communication through a photovoltaic optimizer, wherein the photovoltaic optimizer includes a step-up / step-down and shutdown circuit, a PLC transceiver circuit, and an energy storage inductor L.

[0028] The buck-boost circuit is used by the photovoltaic optimizer to dynamically adjust the output voltage and current of the photovoltaic modules, ensuring that the modules always operate within the voltage range with the highest power generation efficiency. Simultaneously, it converts the electrical energy output by the modules into a voltage value suitable for power line communication. The buck-boost circuit, through the use of switching transistors, inductors, capacitors, and other components, operates in boost mode when the module output voltage is lower than the system requirement, using inductor energy storage and capacitor filtering to raise the low voltage to the target voltage. When the module output voltage is higher than the system requirement, it operates in buck mode, stabilizing the high voltage to the appropriate voltage. This ensures that the photovoltaic modules always output maximum power and achieves voltage matching for power line communication. The shutdown circuit ensures system safety by cutting off the power transmission between the photovoltaic panels and the inverter in the photovoltaic string under specific scenarios, thus providing protection. Specifically, when the system experiences faults such as short circuits, overcurrent, or overvoltage, the shutdown circuit quickly disconnects the circuit path by receiving commands from the controller in the photovoltaic string.

[0029] A PLC (Power Line Communication) transceiver circuit is a module used to enable communication between photovoltaic panels and between photovoltaic panels and external devices. It integrates functions such as encoding / decoding, modulation / demodulation, signal amplification, and filtering. It can convert digital signals to high-frequency carrier signals that can be transmitted over power lines. Simultaneously, through a matching circuit adapted to the characteristics of power lines, it achieves reliable signal transmission and interaction over power lines, enabling communication between devices without additional wiring. Specifically, the PLC transceiver circuit connects the positive terminal PLC+ and the negative terminal PLC- of the transmitting end to the two ends of the energy storage inductor L, thereby storing the power line carrier communication signal on the energy storage inductor L. Because the energy storage inductor L needs to be installed, and the current drawn by the photovoltaic panels when energized is relatively large, a significant amount of heat is generated on the energy storage inductor L, resulting in resource waste. Furthermore, the energy storage inductor L with a low equivalent resistance is relatively expensive.

[0030] Therefore, embodiments of the present invention provide a photovoltaic junction box that enables communication of photovoltaic panels while reducing costs.

[0031] Figure 2 This is a schematic diagram of a photovoltaic system according to an embodiment of the present invention. Figure 2 As shown, the photovoltaic system includes multiple photovoltaic panels. This embodiment of the invention uses three as examples, namely F1, F2, and F3. The photovoltaic panels are connected in series or parallel (this embodiment of the invention uses series connection as an example) to achieve the required voltage and power, thereby supplying power to external devices (such as inverters).

[0032] Each photovoltaic panel includes multiple photovoltaic cells and connecting components. The current generated by the multiple photovoltaic cells connected in series or parallel is collected at the positive and negative terminals of the photovoltaic panel. In this embodiment of the invention, a three-part junction box is used as an example for illustration. The connecting components include a first junction box 1a, a second junction box 1c, and a photovoltaic junction box 1b.

[0033] The first junction box is the positive terminal box, used to connect to the positive terminal of the photovoltaic panel; the second junction box is the negative terminal box, used to connect to the negative terminal of the photovoltaic panel. The photovoltaic junction box is installed between the first and second junction boxes, and contains a bypass circuit and a power line communication circuit. The bypass circuit is used to implement bypass protection, and the power line communication circuit is used to implement power line communication.

[0034] The first and second junction boxes include external connection wires and taps. The tap in the first junction box is used to connect to the positive terminal of the photovoltaic panel, and the tap in the second junction box is used to connect to the negative terminal of the photovoltaic panel. The external connection wires of both junction boxes are used to connect to other photovoltaic panels or power lines.

[0035] A photovoltaic (PV) junction box includes taps and functional components (such as bypass circuits and power line communication circuits). The taps are used to connect to the PV panel. During the PV panel manufacturing process, pre-fabricated metal connecting strips are laid on the PV panel. One metal connecting strip extends from the first junction box to the PV junction box, and another metal connecting strip extends from the second junction box to the PV junction box, thus achieving electrical connection. Therefore, the first junction box, the second junction box, and the PV junction box are connected in series through the same continuous busbar.

[0036] Figure 3 This is a circuit diagram of a photovoltaic junction box according to an embodiment of the present invention, as shown below. Figure 3 As shown, the photovoltaic junction box includes a positive terminal interface PV+, a negative terminal interface PV-, a bypass circuit 11, and a power line communication circuit 12.

[0037] The positive terminal interface PV+ is connected to the positive terminal of the photovoltaic panel directly or indirectly. The negative terminal interface PV- is connected to the negative terminal of the photovoltaic panel directly or indirectly. Specifically, a positive terminal junction box and a negative terminal junction box are provided on the photovoltaic panel. The positive terminal junction box is connected to the positive terminal of the photovoltaic panel, and the negative terminal junction box is connected to the negative terminal of the photovoltaic panel. The positive terminal interface PV+ is connected to the positive terminal junction box, thereby achieving a connection with the positive terminal of the photovoltaic panel, and the negative terminal interface PV- is connected to the negative terminal junction box, thereby achieving a connection with the negative terminal of the photovoltaic panel. Regarding the connection method of the positive terminal interface PV+ and the negative terminal interface PV- to the positive and negative terminal junction boxes, prefabricated metal connecting strips can be laid on the photovoltaic panel during the photovoltaic panel production process. One metal connecting strip extends from the positive terminal junction box to the positive terminal interface PV+ of the photovoltaic terminal junction box, and another metal connecting strip extends from the negative terminal junction box to the negative terminal interface PV- of the photovoltaic terminal junction box.

[0038] Furthermore, the positive and negative terminals of the photovoltaic panel are connected to the power line, providing a channel for power line carrier communication.

[0039] The bypass circuit 11 is connected between the positive terminal PV+ and the negative terminal PV- of the photovoltaic junction box, and is used to bypass the photovoltaic panel from the photovoltaic string circuit in which it is located.

[0040] In one optional implementation, the bypass circuit 11 can be implemented using diodes, wherein the anode of the diode is connected to the negative terminal PV-, and the cathode of the diode is connected to the positive terminal PV+. The photovoltaic panel includes one or more battery strings, and the number of diodes corresponds to the number of battery strings, with each battery string connected in parallel with its corresponding diode. Based on the unidirectional conduction characteristic of diodes, when the battery string is operating normally, its positive terminal voltage is greater than its negative terminal voltage, the diode is turned off, and the battery string is connected in the circuit for normal power generation. When the battery string is shaded, covered with dirt, or damaged, a reverse voltage is generated. At this time, the corresponding diode conducts, providing a bypass for the current, bypassing the shaded or faulty battery string, thereby protecting the battery string from burnout and minimizing power generation loss.

[0041] In another alternative implementation, the bypass circuit 11 can be implemented using a switching transistor and a controller. Figure 4 This is a circuit diagram of the bypass circuit according to an embodiment of the present invention, such as... Figure 4As shown, the bypass circuit includes a switch 111 and a controller 112. In some embodiments, the switch 111 is implemented using an NMOS (Negative channel-Metal-Oxide-Semiconductor) transistor. Specifically, the switch 111 and the controller 112 constitute an ideal diode. The photovoltaic panel includes one or more battery strings, and the number of switches corresponds to the number of battery strings. Each battery string is connected in parallel with a corresponding switch. The controller 112 detects the voltage across each battery string in real time. When the positive voltage of the battery string is less than or equal to the negative voltage, it controls the corresponding switch to turn on. When the positive voltage of the battery string is greater than the negative voltage, it controls the corresponding switch to turn off. This eliminates the forward voltage drop of the diode. At this time, the forward resistance is zero when conducting, and the current can pass through without loss, avoiding the power loss caused by the forward voltage drop of a conventional diode.

[0042] The power line communication circuit 12 is used for data communication via power lines. Specifically, the power line communication circuit 12 is connected to the positive interface PV+ and the negative interface PV-. The positive interface PV+ and the negative interface PV- are connected to the positive and negative terminals of the photovoltaic panel, thereby connecting the power line communication circuit 12 to the positive and negative terminals of the photovoltaic panel. This utilizes the positive and negative conductors of the photovoltaic panel itself as the communication medium to achieve data transmission and status detection of the photovoltaic panel.

[0043] In some embodiments, the power line communication circuit 12 includes a carrier transceiver circuit 121 and a matching circuit 122. In this embodiment, the carrier transceiver circuit 121 is a PLC (Power Line Communication) transceiver circuit. In a power line carrier communication system, the core function of the PLC transceiver circuit is to achieve reliable signal transmission and accurate reception, adapt to the complex transmission environment of power lines, and ensure stable communication.

[0044] The matching circuit 122 is disposed between the positive interface PV+ and the negative interface PV- and connected to the carrier transceiver circuit 121. It is used to acquire a carrier signal from the power line and transmit it to the carrier transceiver circuit 121, or to acquire a carrier signal from the carrier transceiver circuit 121 and transmit it to the power line. The positive interface PV+ and the negative interface PV- are connected to the positive and negative terminals of the photovoltaic panel, thereby connecting the carrier transceiver circuit 121 to the positive and negative terminals of the photovoltaic panel. The matching circuit 122 couples the high-frequency carrier signals output from the positive and negative terminals of the carrier transceiver circuit to the DC power line between the positive and negative terminals of the photovoltaic panel, preventing interference or damage to the carrier transceiver circuit from high DC voltage. Specifically, when the matching circuit 122 receives the carrier signal transmitted in the power line, it achieves impedance matching to make the circuit impedance consistent with the characteristic impedance of the power line, reducing signal reflection loss at the transmission interface and improving the transmission efficiency and stability of the carrier signal on the positive and negative conductors of the photovoltaic panel. Among them, the characteristic impedance of the power line is the core parameter describing the line's own characteristics of signal obstruction and energy transmission when transmitting high-frequency carrier signals. Specifically, it is the equivalent impedance per unit length of the line when the high-frequency signal propagates on the power line.

[0045] The carrier transceiver circuit 121 includes a positive transmitting terminal PLC+ and a negative transmitting terminal PLC-. The main function of the positive transmitting terminal PLC+ is to output a positive voltage signal of the differential signal. When transmitting data, the signal processing unit inside the PLC converts the digital signal into a differential voltage signal. The positive transmitting terminal outputs a positive voltage signal of a specific amplitude, serving as the positive half of the differential signal and providing a positive potential reference for data transmission. The negative transmitting terminal PLC- outputs a negative voltage signal of the differential signal, which, together with the positive voltage signal output from the positive terminal, forms a complete signal transmission loop. Specifically, the negative transmitting terminal outputs a negative voltage with the same amplitude but opposite polarity as the positive voltage, thus forming a differential voltage difference between the positive and negative terminals. By using differential transmission for voltage signal transmission, external interference can be effectively canceled. Since interference signals act on both the positive and negative voltage signals simultaneously, the differential calculation achieves the cancellation of the interference signals, improving the stability of the voltage signal during transmission.

[0046] In some embodiments, the photovoltaic junction box further includes a detection module for measuring at least one of the voltage, temperature, and luminance of the photovoltaic panel. The detection module can be located either outside or inside the photovoltaic junction box. Specifically, the detection module may include at least one of a voltage sensing unit, a temperature sensing unit, and a luminance sensing unit. The voltage sensing unit, coupled to conductive terminals inside the photovoltaic junction box, acquires the DC voltage signal output by the photovoltaic panel in real time. It can detect abnormal data during voltage signal detection and issue an alarm when the voltage exceeds a threshold range, thereby preventing damage to the photovoltaic junction box or photovoltaic panel due to excessive voltage. The temperature sensing unit includes a thermistor module, positioned close to the backsheet of the photovoltaic panel to detect the temperature of the backsheet. Specifically, it issues an alarm when the temperature exceeds a preset range and determines whether to shut down the photovoltaic panel based on instructions sent by maintenance personnel on a terminal device. The luminance sensing unit includes a photoresistor, installed on the side of the junction box facing the light-receiving surface of the photovoltaic panel, to detect the actual light intensity on the surface of the detection component and send the data to the maintenance personnel's terminal device. Maintenance personnel can determine whether a photovoltaic panel is obstructed by detecting the light intensity, and shut down the photovoltaic panel when it is obstructed to avoid affecting the operation of other photovoltaic panels in the photovoltaic string.

[0047] This invention provides a photovoltaic (PV) junction box with positive and negative interfaces for connecting the positive and negative terminals of a PV panel, respectively. Both the positive and negative terminals of the PV panel are connected to power lines. A bypass circuit is provided between the positive and negative interfaces, and a power line communication circuit is also provided between them to enable data communication via the power lines. This achieves PV panel communication without requiring additional components, reducing the cost of the PV panel control system.

[0048] Figure 5 This is a schematic diagram of a photovoltaic control system according to an embodiment of the present invention, as shown below. Figure 5 As shown, this embodiment of the invention specifically illustrates the control of one photovoltaic panel by three junction boxes. It should be understood that when the number of junction boxes corresponding to the photovoltaic panel is different, the principle of controlling the photovoltaic panel based on the junction boxes is similar, and will not be elaborated upon here. In this embodiment, the photovoltaic junction box 1 is located between the first junction box 2 and the second junction box 3. The first junction box 2 and the second junction box 3 are photovoltaic junction boxes without power line communication circuits. The internal connection method of the photovoltaic junction box with a power line communication circuit is as follows: Figure 3The connection method is shown. Specifically, in these three junction boxes, the first junction box 2 and the second junction box 3 are used to connect photovoltaic cables to connect the photovoltaic panel to other photovoltaic panels. The photovoltaic junction box 1 enables communication between the photovoltaic panels by setting up a power line communication circuit 12.

[0049] Specifically, the carrier transceiver circuit 121 in the power line communication circuit 12 is connected to the positive interface PV+ and the negative interface PV- through a matching circuit, thereby connecting to the positive and negative terminals of the photovoltaic panel. This enables communication with the photovoltaic panel. Specifically, when the carrier transceiver circuit 121 receives signals, it extracts high-frequency carrier signals from the power lines of the positive and negative terminals of the photovoltaic panel and converts them into processable digital signals for subsequent analysis. Specifically, the carrier transceiver circuit 121, connected to the matching circuit 122, receives the carrier signal filtered and coupled by the matching circuit 122, and sends the carrier signal to the amplification module in the carrier transceiver circuit 121. This amplifies the carrier signal, which has weakened due to line transmission attenuation, to a suitable amplitude. Then, the demodulation module demodulates the amplified high-frequency carrier signal, thereby restoring the original data carried in the signal. This completes the reception and analysis of the power line carrier communication signal. When the carrier transceiver circuit 121 transmits a signal, it converts the received operation command into a high-frequency carrier signal that can be transmitted on the power line, and couples it to the power line between the positive and negative terminals of the photovoltaic panel through a matching circuit. Specifically, the carrier transceiver circuit 121 receives digital signals sent by the microcontroller of the photovoltaic panel, encodes the data to form frame structure data that conforms to the transmission specification, and then modulates the encoded digital signal onto a high-frequency carrier to convert the low-frequency digital signal into a high-frequency signal suitable for power line transmission. The modulated high-frequency carrier signal is then amplified to increase the signal strength, and the amplified high-frequency carrier signal is transmitted to the matching circuit. After impedance matching is performed by the matching circuit 122, the high-frequency carrier signal is coupled to the power line between the positive and negative terminals of the photovoltaic panel, thereby realizing the transmission of data on the power line.

[0050] This invention provides a photovoltaic (PV) junction box with positive and negative interfaces for connecting the positive and negative terminals of a PV panel, respectively. Both the positive and negative terminals of the PV panel are connected to power lines. A bypass circuit is provided between the positive and negative interfaces, and a power line communication circuit is also provided between them to enable data communication via the power lines. This achieves PV panel communication without requiring additional components, reducing the cost of the PV panel control system.

[0051] In some embodiments, besides connecting the power line communication circuit 12 to the photovoltaic junction box 1 with communication function, it can also be connected to the positive and negative interfaces of other photovoltaic junction boxes to connect to the positive and negative terminals of the photovoltaic panel, thereby achieving the same effect and increasing the equivalent load, thus allowing for a larger voltage signal to be received when receiving PLC control signals. Specifically, as follows... Figure 6 As shown, Figure 6 This is a schematic diagram of a photovoltaic control system according to another embodiment of the present invention, wherein the first junction box 2 and the second junction box 3 are conventional photovoltaic junction boxes without carrier transceiver circuits, and the photovoltaic junction box 1 is disposed between the first junction box 2 and the second junction box 3. The internal connection structure of the photovoltaic junction box 1 is as follows. Figure 3 As shown. With Figure 5 The photovoltaic control system shown differs in structure in that the positive interface of photovoltaic junction box 1 is connected to the positive interface of first junction box 2, and the negative interface of photovoltaic junction box 1 is connected to the negative interface of second junction box 3. Specifically, first junction box 2 and second junction box 3 also include a positive interface PV+ and a negative interface PV-. The positive terminal PLC+ of the power line communication circuit is led out from point C and connected to point A, and the negative terminal PLC- of the power line communication circuit is led out from point D and connected to point B. Points C and D are the positive and negative interfaces of photovoltaic junction box 1, respectively; point A is the positive interface of first junction box 2; and point B is the negative interface of second junction box 3. This connection method alters the internal design of the photovoltaic panel. However, the connection points of the positive and negative terminals of the power line communication circuit are now farther apart, allowing the power line communication circuit to receive a larger signal, thereby improving the quality of photovoltaic communication.

[0052] On the other hand, in some embodiments, the photovoltaic junction box further includes a voltage acquisition circuit. This voltage acquisition circuit can be connected between the positive and negative terminals, or between the first contact and the positive terminal, or between the second contact and the negative terminal, to measure the voltage value between the two points, thereby obtaining the voltage situation between various points on the photovoltaic panel. Specifically, it can be connected between points A and C, or between points C and D, or between points D and B in the diagram, to measure the voltage between the two points. Specifically, the voltage acquisition circuit can be implemented using a resistor divider circuit, a voltage transformer circuit, a linear optocoupler isolation circuit, or other circuits. By setting voltage acquisition circuits in different locations, the voltage situation between various points throughout the entire photovoltaic panel can be measured, thereby better enabling the detection of the photovoltaic panel.

[0053] This invention provides a photovoltaic (PV) junction box with positive and negative interfaces for connecting the positive and negative terminals of a PV panel, respectively. Both the positive and negative terminals of the PV panel are connected to power lines. A bypass circuit is provided between the positive and negative interfaces, and a power line communication circuit is also provided between them to enable data communication via the power lines. This achieves PV panel communication without requiring additional components, reducing the cost of the PV panel control system.

[0054] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A photovoltaic junction box, characterized in that, The photovoltaic junction box includes: A positive terminal interface is used to connect to the positive terminal of a photovoltaic panel, which is connected to a power line. The negative terminal interface is used to connect to the negative terminal of the photovoltaic panel, which is connected to the power line. The bypass circuit is connected between the positive and negative terminals of the photovoltaic junction box. A power line communication circuit, connecting the positive and negative interfaces, is used for data communication via the power line.

2. The photovoltaic junction box according to claim 1, characterized in that, The power line communication circuit includes: The carrier transceiver circuit includes a positive terminal and a negative terminal. A matching circuit, disposed between the positive and negative interfaces and connected to the carrier transceiver circuit, is used to obtain a carrier signal from the power line and send it to the carrier transceiver circuit, or to obtain a carrier signal from the carrier transceiver circuit and send it to the power line.

3. The photovoltaic junction box according to claim 1, characterized in that, The bypass circuit includes a switching transistor and a controller; The controller is used to control the switch to turn on when the voltage at the positive terminal is less than that at the negative terminal, and to control the switch to turn off when the voltage at the positive terminal is greater than or equal to that at the negative terminal.

4. The photovoltaic junction box according to claim 1, characterized in that, The photovoltaic panel is also provided with a first junction box and a second junction box. The first junction box is used to connect to the positive terminal of the photovoltaic panel, and the second junction box is used to connect to the negative terminal of the photovoltaic panel. The photovoltaic junction box is connected between the first junction box and the second junction box.

5. The photovoltaic junction box according to claim 4, characterized in that, The positive terminal of the photovoltaic junction box is connected to the negative terminal of the first junction box, and the photovoltaic junction box is connected to the positive terminal of the second junction box.

6. The photovoltaic junction box according to claim 4, characterized in that, The positive terminal of the photovoltaic junction box is connected to the positive terminal of the first junction box, and the negative terminal of the photovoltaic junction box is connected to the negative terminal of the second junction box.

7. The photovoltaic junction box according to claim 1, characterized in that, The photovoltaic junction box also includes: The detection module is used to detect at least one of the following: voltage, temperature, and light intensity of the photovoltaic panel.

8. The photovoltaic junction box according to claim 6, characterized in that, The photovoltaic junction box also includes: A voltage acquisition circuit is connected between the first and second interfaces to measure the voltage between the two interfaces.

9. The photovoltaic junction box according to claim 8, characterized in that, The first interface is the positive terminal of the photovoltaic junction box, and the second interface is the negative terminal of the photovoltaic junction box; or The first interface is the positive terminal of the first junction box, and the second interface is the positive terminal of the photovoltaic junction box; or The first interface is the negative terminal of the photovoltaic junction box, and the second interface is the negative terminal of the second junction box.

10. A photovoltaic panel control system, characterized in that, The system includes: Photovoltaic panels; At least one photovoltaic junction box as described in any one of claims 1-9 is disposed on the photovoltaic panel.

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