Photovoltaic junction boxes and photovoltaic modules

Abstract

The present application relates to a photovoltaic junction box, which is connected to a photovoltaic cell string, comprising a box body, which is installed on a photovoltaic module and connected to the corresponding photovoltaic cell string in the photovoltaic module; an output cable, one end of which is connected to the output end of the box body; a connector, which is installed at the other end of the output cable; a linkage switch group, which is arranged in the box body; the linkage switch group comprises a normally closed switch and a normally open switch, the normally closed switch is connected in series to the photovoltaic cell string to form a photovoltaic branch, and the normally open switch is connected in parallel with the photovoltaic branch; the normally closed switch and the normally open switch are of a linkage structure, when one of the normally closed switch and the normally open switch is turned on, the other is turned off; the change of the on-off state of the normally closed switch and the normally open switch is triggered by the temperature in the photovoltaic junction box, when the temperature in the box body reaches a preset high temperature threshold, the normally closed switch becomes a disconnected state, and the normally open switch becomes a conducting state; when the temperature in the box body reaches a preset low temperature threshold, the normally closed switch returns to a conducting state, and the normally open switch returns to a disconnected state.

Description

Technical Field

[0001] The utility model relates to a photovoltaic junction box and a photovoltaic component, belonging to the technical field of solar cells. Background Art

[0002] In the design of photovoltaic modules, the junction box is the only component that connects the photovoltaic cell string in the module for electrical output. Through the output cable of the junction box on the photovoltaic module, several photovoltaic modules are electrically connected in series to form a certain voltage, drive the inverter to work, and realize the conversion of DC to AC.

[0003] A bypass protection diode is usually installed in the junction box. It is the only protection device when the photovoltaic cell is blocked and produces a hot spot. When the bypass protection diode is turned on, it will generate high temperature. As the size of the photovoltaic cell increases, the current passing through the bypass protection diode also increases, which will cause the bypass protection diode to generate higher temperature when it is working. Alternatively, when the metal conductor is not connected during welding or installation inside the junction box, the contact resistance between the metal parts will increase, causing DC arcing, and the high heat generated by the DC arc can reach more than 1000 degrees Celsius. The above situations will cause the temperature inside the junction box to be too high, causing the junction box to burn, or even cause a fire.

[0004] In order to solve the above problems, in the prior art, large-size diode chips are usually used to reduce the current density on the unit chip to achieve diode cooling. However, as the size efficiency of photovoltaic cells increases, the current becomes higher and higher. After the diode is turned on, it is close to the theoretical junction temperature of the diode, and there is no more room for temperature rise. Or, as in patent 201620041691.4, a temperature fuse is connected in series with the photovoltaic cell string in the junction box to limit the high temperature in the junction box. When the temperature of the junction box reaches a dangerous high temperature, the fuse blows to automatically shut down the output of the photovoltaic modules in series, making the current of the photovoltaic modules zero. However, in the photovoltaic system, each photovoltaic module is connected in series. Cutting off the connection of one photovoltaic module cuts off the electrical connection of the entire photovoltaic system, which will stop all photovoltaic modules from generating electricity and affect the normal use of the photovoltaic system. Utility Model Content

[0005] The purpose of the utility model is to provide a photovoltaic junction box which can automatically cut off the output of a photovoltaic module or a photovoltaic cell string under high temperature conditions to prevent the temperature of the corresponding photovoltaic module from continuing to rise, and automatically bypass the photovoltaic junction box of only the dangerous high-temperature photovoltaic module in the photovoltaic module, so that the corresponding photovoltaic module will not affect the use of other photovoltaic modules in the photovoltaic system after being shut down at high temperature, thereby ensuring the safety of the use of the photovoltaic module and improving the use efficiency of the photovoltaic system.

[0006] In order to achieve the above object, the utility model provides the following technical solutions:

[0007] A photovoltaic junction box is installed on a photovoltaic module and connected to a photovoltaic cell string in the photovoltaic module, comprising:

[0008] A box body is mounted on the photovoltaic module and connected to a corresponding photovoltaic cell string in the photovoltaic module;

[0009] An output cable, one end of which is connected to the output end of the box body;

[0010] A connector mounted at the other end of the output cable; and

[0011] A linkage switch group is arranged in the box body;

[0012] The linkage switch group includes a normally closed switch and a normally open switch, the normally closed switch is connected in series to the photovoltaic cell string to form a photovoltaic branch, and the normally open switch is connected in parallel to the photovoltaic branch; the normally closed switch and the normally open switch are in a linkage structure, when one of the normally closed switch and the normally open switch is turned on, the other is turned off;

[0013] The change of the on / off state of the normally closed switch and the normally open switch is triggered by the temperature inside the photovoltaic junction box. When the temperature inside the box reaches a preset high temperature threshold, the normally closed switch becomes an off state, and the normally open switch becomes an on state; when the temperature inside the box reaches a preset low temperature threshold, the normally closed switch returns to an on state, and the normally open switch returns to an off state.

[0014] Furthermore, the change of the states of the normally closed switch and the normally open switch is achieved by the deformation of the metal in the linkage switch group as the temperature changes, and the disconnection and conduction are achieved in a jump form;

[0015] The linkage switch group has a normally closed contact, a normally open contact and a common contact. The normally closed contact and the common contact form the normally closed switch, and the normally open contact and the common contact form the normally open switch.

[0016] Further, the photovoltaic junction box includes a controller and a temperature sensor connected to the controller signal, the temperature sensor is used to monitor the temperature inside the box body, and the normally closed switch and the normally open switch are both electrically connected to the controller;

[0017] The controller controls the normally closed switch to be disconnected and the normally open switch to be turned on, or controls the normally closed switch to be turned on and the normally open switch to be disconnected according to the temperature in the box body monitored by the temperature sensor.

[0018] Furthermore, a bypass protection diode is also arranged in the box body of the photovoltaic junction box.

[0019] Furthermore, a linkage switch group and a bypass protection diode are arranged in the box body of the photovoltaic junction box, and the bypass protection diode is connected in parallel to the photovoltaic branch, and the number of photovoltaic cell strings on the photovoltaic branch is one string.

[0020] Furthermore, the photovoltaic assembly is provided with a plurality of photovoltaic cell strings, and each photovoltaic cell string is correspondingly provided with one photovoltaic junction box.

[0021] Furthermore, at least two bypass protection diodes and a linkage switch group are arranged in the box body of the photovoltaic junction box, the bypass protection diodes are connected in parallel on the photovoltaic branch, the number of photovoltaic cell strings on the photovoltaic branch is one string, and each bypass protection diode is arranged corresponding to one string of the photovoltaic cell strings.

[0022] Furthermore, it also includes a thermochromic component, which is arranged on the outer wall of the box body and the outer wall of the connector. The thermochromic component has a preset thermochromic threshold. When the temperature of the box body and / or the connector reaches the preset thermochromic threshold, the corresponding thermochromic component undergoes an irreversible color change.

[0023] Furthermore, the preset temperature-sensitive color-changing threshold of the temperature-sensitive color-changing element includes a high temperature color-changing threshold and a low temperature color-changing threshold, and the temperature-sensitive color-changing element is correspondingly provided with two variable colors;

[0024] When the temperature of the box body and / or the connector reaches the high-temperature color change threshold or the low-temperature color change threshold, the temperature-sensitive color-changing component undergoes an irreversible color change of a different color accordingly.

[0025] The utility model also provides a photovoltaic assembly, comprising:

[0026] Photovoltaic cell strings; and

[0027] The photovoltaic junction box as described in any one of the above items is connected to the photovoltaic cell string.

[0028] The beneficial effects of the utility model are:

[0029] When the temperature inside the photovoltaic junction box provided by the present application is higher than a preset high temperature threshold, the normally closed switch is disconnected to autonomously shut down the photovoltaic junction box and the connected photovoltaic cell string circuit, so as to prevent the photovoltaic junction box from being burned by high temperature or the corresponding photovoltaic module from catching fire, thereby ensuring the long-term safety of the photovoltaic module. At the same time, the normally open switch is turned on, so that the connection line of the photovoltaic junction box is automatically bypassed to the branch where the normally open switch is located, so that when the output of the problematic photovoltaic module is turned off, the connection between other normally operating photovoltaic modules can be maintained, so as to avoid the entire photovoltaic module string being broken due to the high temperature shutdown of some photovoltaic modules in the photovoltaic module string, thereby affecting the output of other normally operating photovoltaic modules. In addition, when the temperature inside the photovoltaic junction box drops to the preset low temperature threshold, the disconnected photovoltaic module will automatically resume the normal connection state. Compared with the prior art, there is no need to manually replace the fuse, which is more convenient to use. While ensuring the safety of the use of photovoltaic modules, the utilization efficiency of the photovoltaic system can be improved.

[0030] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the utility model in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the circuit structure in which the linkage switch group in the photovoltaic junction box of the utility model is connected to the input end of the photovoltaic junction box;

[0032] Figure 2 It is a schematic diagram of the circuit structure in which the linkage switch group in the photovoltaic junction box of the utility model is connected to the output end of the photovoltaic junction box;

[0033] Figure 3 It is a schematic diagram of the circuit structure after the linkage switch group, photovoltaic cell string and bypass protection diode in the photovoltaic junction box of the utility model are connected;

[0034] Figure 4 It is a structural schematic diagram of the connection between a photovoltaic cell string and a bypass protection diode, a busbar jack and a linkage switch group in a photovoltaic junction box in an optional implementation scheme of the utility model;

[0035] Figure 5 It is a schematic diagram of the circuit structure of a split photovoltaic junction box connected to a photovoltaic module;

[0036] Figure 6 This is a schematic diagram of the circuit structure of a centralized photovoltaic junction box connected to a photovoltaic module.

[0037] Description of reference numerals:

[0038] 2-photovoltaic cell string; 3-normally closed switch; 4-normally closed contact; 5-common contact; 6-normally open switch; 7-normally open contact; 8-bypass protection diode; 10-photovoltaic junction box. DETAILED DESCRIPTION

[0039] The technical solution of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0040] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0041] In the present application, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity directions; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above-mentioned directional words are not used to limit the present application.

[0042] The photovoltaic module of the present application includes a photovoltaic cell string and a photovoltaic junction box, which is installed on the photovoltaic module and connected to the photovoltaic cell string in the photovoltaic module. The photovoltaic junction box is a connecting device between the photovoltaic cell string array formed by the photovoltaic module and the photovoltaic charging control device. Its main function is to connect multiple photovoltaic modules in series to form a photovoltaic module string, and connect the power generated by the photovoltaic cell string corresponding to each photovoltaic module to the external line to conduct the current generated by the photovoltaic cell string.

[0043] In one embodiment, the photovoltaic junction box includes a box body, an output cable connected to the output end of the box body at one end, a connector installed at the other end of the output cable, and a linkage switch group arranged in the box body. The box body is installed on the photovoltaic module and connected to the corresponding photovoltaic cell string in the photovoltaic module. The connector is also commonly known as a wiring terminal or a quick connector. It is a key part for interconnecting various components such as photovoltaic modules, junction boxes, controllers and inverters in a photovoltaic power generation system. It is a conventional setting and will not be described here. Among them, the linkage switch group is used to automatically shut down and bypass the photovoltaic junction box of the photovoltaic module that has a dangerously high temperature.

[0044] For details, see Figure 1 and Figure 2The linkage switch group includes a normally closed switch 3 and a normally open switch 6. The normally closed switch 3 is connected in series to the photovoltaic cell string 2 to form a photovoltaic branch, and the normally open switch 6 is connected in parallel to the photovoltaic branch. The normally closed switch 3 and the normally open switch 6 are a linkage structure. When one of the normally closed switch 3 and the normally open switch 6 is turned on, the other is turned off. Among them, the normally closed switch 3 can be connected to the positive electrode of the photovoltaic cell string 2, and can also be connected to the negative electrode of the photovoltaic cell string 2. This application does not limit this and can be adjusted in combination with design requirements.

[0045] The change of the on / off state of the normally closed switch 3 and the normally open switch 6 is triggered by the temperature inside the photovoltaic junction box 10. When the temperature inside the box body (not shown) reaches a preset high temperature threshold, the normally closed switch 3 becomes an off state, and the normally open switch 6 becomes an on state. When the temperature inside the box body reaches a preset low temperature threshold, the normally closed switch 3 returns to an on state, and the normally open switch 6 returns to an off state.

[0046] It should be noted that the above-mentioned preset high temperature threshold and preset low temperature threshold can be adjusted according to actual design requirements, that is, the trigger temperature of the on and off states of the normally closed switch 3 and the normally open switch 6 can be adjusted to make the photovoltaic junction box 10 of the present application more applicable.

[0047] Through the above structure, when the temperature inside the photovoltaic junction box 10 is higher than the preset high temperature threshold, the normally closed switch 3 is disconnected to automatically shut down the photovoltaic junction box 10 and the connected photovoltaic cell string 2 circuit, so as to prevent the photovoltaic junction box 10 from being burned by high temperature or the corresponding photovoltaic module from catching fire, thereby ensuring the long-term safety of the photovoltaic module. At the same time, the normally open switch 6 is turned on, so that the connection line of the photovoltaic junction box 10 is automatically bypassed to the branch where the normally open switch 6 is located, so that when the output of the problematic photovoltaic module is turned off, the connection between other normally operating photovoltaic modules can be maintained, so as to avoid the entire photovoltaic module string being broken due to the high temperature shutdown of some photovoltaic modules in the photovoltaic module string, thereby affecting the output of other normally operating photovoltaic modules. In addition, when the temperature inside the photovoltaic junction box 10 drops to the preset low temperature threshold, the disconnected photovoltaic module will automatically restore to the normal connection state. Compared with the prior art, there is no need to manually replace the fuse, which is more convenient to use. While ensuring the safety of the use of photovoltaic modules, the use efficiency of the photovoltaic system can be improved.

[0048] As is known, photovoltaic modules have hot spot effect, which refers to the phenomenon that the blocked or defective areas in the photovoltaic module string in the power generation state are treated as loads, consuming the energy generated by other areas, resulting in local overheating. The hot spot effect will reduce the output power of photovoltaic modules to a certain extent. If the heating temperature exceeds a certain limit, it will cause permanent damage such as local burning of photovoltaic modules to form dark spots, melting of solder joints, aging of packaging materials, etc. It is an important factor affecting the output power and service life of photovoltaic modules, and may even cause safety hazards.

[0049] See above. Figure 3 In order to avoid the reduction of conversion efficiency of the photovoltaic module due to the hot spot effect, a bypass protection diode 8 is also provided in the box body of the photovoltaic junction box 10. Specifically, the bypass protection diode 8 is connected in parallel to the photovoltaic branch.

[0050] By connecting a bypass protection diode 8 in parallel to the photovoltaic branch connected to the photovoltaic cell string 2, the influence of the hot spot effect on the power generation of the photovoltaic module can be reduced. Under normal circumstances, the bypass protection diode 8 is in reverse bias, and the bypass protection diode 8 does not conduct and does not affect the normal operation of the module. When there is a shielding, due to the series circuit, the other photovoltaic cell strings 2 promote their reverse bias to become a large resistance. At this time, the bypass protection diode 8 is turned on, and the shielded photovoltaic cell string 2 is short-circuited and removed from the circuit, and the circuit is connected by the bypass protection diode 8.

[0051] It should be noted that, since a linkage switch group is provided in the box body of the junction box of the present application, and the normally closed switch 3 is connected in series with the photovoltaic cell string 2 and then in parallel with the normally open switch 6, and at the same time, the bypass protection diode 8 is connected in parallel to the photovoltaic cell string 2, so that after the originally large current photovoltaic cell string 2 is blocked, the bypass protection diode 8 can use a diode with a smaller chip area to achieve the bypass protection function requirements when the photovoltaic module or the photovoltaic cell string 2 is in an open circuit state, without increasing the diode chip area to bear the heat dissipation function under the safety factor requirements, thereby saving the diode cost and achieving a safer effect.

[0052] See also Figure 4 In this embodiment, the change of the state of the normally closed switch 3 and the normally open switch 6 is realized by the deformation of the metal in the linkage switch group with the temperature change, and the disconnection and conduction are realized in the form of jump. The linkage switch group has a normally closed contact 4, a normally open contact 7 and a common contact 5. The normally closed contact 4 and the common contact 5 form the normally closed switch 3, and the normally open contact 7 and the common contact 5 form the normally open switch 6. Among them, the common contact 5 is connected to the output end or the input end of the photovoltaic junction box 10.

[0053] Specifically, the above-mentioned linkage switch group can be a bipolar temperature control switch, which is a component that uses two groups of bimetallic strips after being set at a constant temperature as a heat-sensitive reaction. When the temperature in the photovoltaic junction box 10 rises, the heat generated is simultaneously transferred to the bimetallic strips forming the normally closed contact 4 and the bimetallic strips forming the normally open contact 7. When the preset high temperature threshold is reached, it quickly acts, and the normally closed contact 4 is disconnected and the normally open contact 7 is closed through the mechanism; when the temperature drops to the preset low temperature threshold, the bimetallic strips corresponding to the normally closed contact 4 and the normally open contact 7 quickly return to their original state, so that the normally closed contact 4 is closed and the normally open contact 7 is disconnected, thereby achieving the purpose of connecting or disconnecting the circuit of the corresponding photovoltaic component or photovoltaic cell string 2, thereby controlling the circuit.

[0054] In another optional embodiment, the photovoltaic junction box 10 includes a controller (not shown) and a temperature sensor (not shown) connected to the controller signal, the temperature sensor is used to monitor the temperature in the box body, and the normally closed switch 3 and the normally open switch 6 are both electrically connected to the controller. The controller controls the normally closed switch 3 to be disconnected and the normally open switch 6 to be turned on according to the temperature in the box body monitored by the temperature sensor, or controls the normally closed switch 3 to be turned on and the normally open switch 6 to be disconnected. Among them, the controller can be a single-chip microcomputer or a control circuit, and the temperature sensor refers to a sensor that can sense temperature and convert it into a usable output signal. They are all conventional settings and are not described in detail here.

[0055] As described above, in order to improve the compactness of the photovoltaic junction box 10, the controller and the temperature sensor are arranged in the box body. The controller is arranged in the box body of the junction box to protect the controller, and the temperature sensor is arranged in the junction box to make its monitoring result more accurate.

[0056] It should be noted that the photovoltaic junction box 10 may be a centralized photovoltaic junction box 10 or a split photovoltaic junction box 10. The specific configuration may be adjusted in accordance with design requirements, and this application does not make any specific limitation thereto.

[0057] Take this embodiment as an example, see Figure 5 Combined with Figure 4 When the photovoltaic junction box 10 is a split photovoltaic junction box 10, multiple photovoltaic cell strings 2 are arranged on each photovoltaic module, and each photovoltaic cell string 2 is correspondingly provided with a photovoltaic junction box 10. A linkage switch group and a bypass protection diode 8 are arranged in the box body of each photovoltaic junction box 10. The bypass protection diode 8 is connected in parallel on the photovoltaic branch, and the number of photovoltaic cell strings 2 on the photovoltaic branch is one string.

[0058] Specifically, the photovoltaic cell string 2 and the photovoltaic junction box 10 are arranged in a one-to-one arrangement. The photovoltaic units formed by connecting the three photovoltaic junction boxes 10 to the corresponding photovoltaic cell string 2 are named the first photovoltaic unit A, the second photovoltaic unit B and the third photovoltaic unit C in sequence. The three photovoltaic units are connected in series in sequence. The photovoltaic junction box 10 on each photovoltaic unit is provided with a first busbar jack (not shown), a second busbar jack (not shown) and a third busbar jack (not shown). The first busbar jack is connected to the normally open contact 7, the second busbar jack is connected to the normally closed contact 4, and the third busbar jack is connected to the common contact 5. The first busbar jack and the second busbar jack are connected to the corresponding photovoltaic cell string 2, and the two ends of the bypass protection diode 8 are connected to the first busbar jack and the third busbar jack. The third busbar serves as the output terminal PV-.

[0059] See also Figure 6When the photovoltaic junction box 10 is a centralized photovoltaic junction box 10, a photovoltaic junction box 10 is arranged on the photovoltaic assembly, and at least two bypass protection diodes 8 and a linkage switch group are arranged in the box body of the photovoltaic junction box 10. The bypass protection diodes 8 are connected in parallel on the photovoltaic branch. The number of photovoltaic cell strings 2 on the photovoltaic branch is one string, and each bypass protection diode 8 is arranged corresponding to one photovoltaic cell string 2.

[0060] Specifically, the photovoltaic cell strings 2 and the bypass protection diodes 8 are arranged in a one-to-one arrangement, and the three photovoltaic cell strings 2 are connected in series. The three photovoltaic cell strings are named as the first to third photovoltaic cell strings 2, and the three bypass protection diodes 8 are named as the first to third bypass protection diodes 8. The box body is provided with a first busbar jack (not shown), a second busbar jack (not shown), a third busbar jack (not shown), and a fourth busbar jack (not shown). The first busbar jack is connected to the normally open contact 7, the fourth busbar jack is connected to the normally closed contact 4, and the common contact 5 is connected to the output terminal PV- of the photovoltaic junction box 10.

[0061] The first photovoltaic cell string 2 is connected to the first busbar socket and the second busbar socket, the second photovoltaic cell string 2 is connected to the second busbar socket and the third busbar socket, and the third photovoltaic cell string 2 is connected to the third busbar socket and the fourth busbar socket.

[0062] The first bypass protection diode 8 is connected to the first busbar jack and the second busbar jack, the second bypass protection diode 8 is connected to the second busbar and the third busbar jack, and the third bypass protection diode 8 is connected to the third busbar jack and the output terminal PV- of the photovoltaic junction box 10.

[0063] In order to facilitate maintenance personnel to repair or replace the photovoltaic components that are shut down by high temperature, the photovoltaic junction box 10 also includes a thermochromic component (not shown), which is arranged on the outer wall of the box body and the outer wall of the connector (not shown), and the thermochromic component has a preset thermochromic threshold. When the temperature of the box body and / or the connector reaches the preset thermochromic threshold, the corresponding thermochromic component undergoes an irreversible color change. When the photovoltaic component generates high temperature, the thermochromic component at the corresponding position undergoes an irreversible color change, so that maintenance personnel can directly find the location where the high temperature occurs during maintenance, thereby improving maintenance efficiency and improving the safety of the photovoltaic system.

[0064] As described above, in order to improve the display accuracy of the thermochromic element, the preset thermochromic threshold of the thermochromic element includes a high temperature discoloration threshold and a low temperature discoloration threshold, and the thermochromic element is correspondingly provided with two variable colors. When the temperature of the box body and / or the connector reaches the high temperature discoloration threshold or the low temperature discoloration threshold, the thermochromic element correspondingly undergoes an irreversible color change of different colors.

[0065] In this embodiment, the thermochromic element can be a temperature indicating paper pasted on the photovoltaic junction box 10 and the outer wall of the connector, or a thermochromic paint applied on the photovoltaic junction box 10 and the outer wall of the connector. This application does not limit the type and color of the thermochromic element, which can be selected according to design requirements.

[0066] Obviously, the embodiments described above are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, ordinary technicians in this field can make other different forms of changes or modifications without making creative work, which should all fall within the scope of protection of the present application.

Claims

1. A photovoltaic junction box, mounted on a photovoltaic module and connected to a photovoltaic cell string in the photovoltaic module, characterized in that: include: A box body is mounted on the photovoltaic module and connected to a corresponding photovoltaic cell string in the photovoltaic module; An output cable, one end of which is connected to the output end of the box body; A connector installed at the other end of the output cable; and A linkage switch group is arranged in the box body; The linkage switch group includes a normally closed switch and a normally open switch, the normally closed switch is connected in series to the photovoltaic cell string to form a photovoltaic branch, and the normally open switch is connected in parallel to the photovoltaic branch; the normally closed switch and the normally open switch are in a linkage structure, when one of the normally closed switch and the normally open switch is turned on, the other is turned off; The change of the on / off state of the normally closed switch and the normally open switch is triggered by the temperature inside the photovoltaic junction box. When the temperature inside the box reaches a preset high temperature threshold, the normally closed switch becomes an off state, and the normally open switch becomes an on state; when the temperature inside the box reaches a preset low temperature threshold, the normally closed switch returns to an on state, and the normally open switch returns to an off state.

2. The photovoltaic junction box according to claim 1, characterized in that: The change of the states of the normally closed switch and the normally open switch is achieved by the deformation of the metal in the linkage switch group as the temperature changes, and the disconnection and conduction are achieved in a jump form; The linkage switch group has a normally closed contact, a normally open contact and a common contact. The normally closed contact and the common contact form the normally closed switch, and the normally open contact and the common contact form the normally open switch.

3. The photovoltaic junction box according to claim 1, characterized in that: The photovoltaic junction box includes a controller and a temperature sensor connected to the controller signal, the temperature sensor is used to monitor the temperature inside the box body, and the normally closed switch and the normally open switch are both electrically connected to the controller; The controller controls the normally closed switch to be disconnected and the normally open switch to be turned on, or controls the normally closed switch to be turned on and the normally open switch to be disconnected according to the temperature in the box body monitored by the temperature sensor.

4. The photovoltaic junction box according to any one of claims 1 to 3, characterized in that: A bypass protection diode is also arranged in the box body of the photovoltaic junction box.

5. The photovoltaic junction box according to claim 4, characterized in that: A linkage switch group and a bypass protection diode are arranged in the box body of the photovoltaic junction box. The bypass protection diode is connected in parallel to the photovoltaic branch. The number of photovoltaic cell strings on the photovoltaic branch is one string.

6. The photovoltaic junction box according to claim 5, characterized in that: The photovoltaic assembly is provided with a plurality of photovoltaic cell strings, and each photovoltaic cell string is correspondingly provided with one photovoltaic junction box.

7. The photovoltaic junction box according to claim 4, characterized in that: At least two bypass protection diodes and a linkage switch group are arranged in the box body of the photovoltaic junction box. The bypass protection diodes are connected in parallel on the photovoltaic branch. The number of photovoltaic cell strings on the photovoltaic branch is one string, and each bypass protection diode is arranged corresponding to one string of the photovoltaic cell strings.

8. The photovoltaic junction box according to claim 1, characterized in that: It also includes a thermochromic component, which is arranged on the outer wall of the box body and the outer wall of the connector. The thermochromic component has a preset thermochromic threshold. When the temperature of the box body and / or the connector reaches the preset thermochromic threshold, the corresponding thermochromic component undergoes an irreversible color change.

9. The photovoltaic junction box according to claim 8, characterized in that: The preset temperature-sensitive color-changing threshold of the temperature-sensitive color-changing element includes a high temperature color-changing threshold and a low temperature color-changing threshold, and the temperature-sensitive color-changing element is correspondingly provided with two variable colors; When the temperature of the box body and / or the connector reaches the high-temperature color change threshold or the low-temperature color change threshold, the temperature-sensitive color-changing component correspondingly undergoes an irreversible color change of a different color.

10. A photovoltaic module, characterized in that: include: Photovoltaic cell strings; and The photovoltaic junction box according to any one of claims 1 to 9, connected to the photovoltaic cell string.

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