Photovoltaic module junction box and photovoltaic system

Abstract

The utility model relates to a photovoltaic module junction box and a photovoltaic system, the photovoltaic module junction box comprises a positive junction box, a middle junction box and a negative junction box, each junction box comprises a first diode and a second diode, and the anode of the first diode is connected with the cathode of the second diode; the anodes of the first diodes in the junction boxes are connected with jumper wire nodes in the first battery pack and the second battery pack in the battery units in a one-to-one correspondence manner through jumper wires; the jumper node is a series connection node of the first battery string and the second battery string. According to the photovoltaic module junction box, the reverse bias voltage borne by each diode in the working process is 1 / 6 open-circuit voltage, and compared with 1 / 3 open-circuit voltage borne by each diode in the prior art, the reverse bias voltage can be reduced by half, so that the thermal escape capacity of each diode in the junction box can be greatly improved, and the reliability and safety of the photovoltaic module junction box are improved.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic module junction boxes, and particularly to photovoltaic module junction boxes and photovoltaic systems. Background Art

[0002] As a clean energy source that is inexhaustible, solar energy has increasingly attracted the attention of people from all walks of life. However, with the increasing demand for the coverage rate of solar cells per unit area and the need to reduce costs, the size of solar cell wafers has been continuously increasing, and the short-circuit current and open-circuit voltage of the corresponding modules have also become larger. Accordingly, the performance requirements for bypass diodes have become higher and higher. Currently, the mainstream bypass diode solution is that one diode corresponds to a string of cells. When a hot spot occurs in a photovoltaic module, the shading of one cell wafer will cause a 1 / 6 power loss; and during normal operation, the voltage borne by one diode is 1 / 3 Voc, which poses a great test to the reverse ability of the diode at high temperatures. At the same time, if the diode is broken down and damaged, the corresponding string of cells will be open-circuited, resulting in a large power loss. Summary of the Utility Model

[0003] Based on this, it is necessary to provide a photovoltaic module junction box and a photovoltaic system for the above technical problems.

[0004] In a first aspect, the present application provides a photovoltaic module junction box. The photovoltaic module includes a plurality of battery units, and the battery units are connected in parallel with each other. Each battery unit includes a first battery group and a second battery group, and the first battery group and the second battery group are connected in parallel. Each battery group includes a first battery string and a second battery string connected in series; the junction box includes a positive junction box, an intermediate junction box, and a negative junction box. Each junction box includes a first diode and a second diode, and the anode of the first diode is connected to the cathode of the second diode;

[0005] Among them, the anode of the first diode in each junction box is connected to the jumper node in the first battery group and the second battery group in each battery unit through a jumper wire one by one; the jumper node is the series connection node of the first battery string and the second battery string.

[0006] In one embodiment, each junction box further includes a conductive sheet, and the conductive sheet is connected to each diode in the same junction box for electrically connecting each diode and the bus bar of the photovoltaic module.

[0007] In one embodiment, the conductive sheet is further provided with through holes to enable the bus bar of the photovoltaic module to be electrically connected to each diode through the through holes.

[0008] In one embodiment, the number of the conductive sheets is one, and the number of the through holes is three.

[0009] In one embodiment, the diode chips in each of the diodes include one of a Schottky planar diode chip, a Schottky trench diode chip, and a MOSFET diode chip.

[0010] In one embodiment, the package structure of each of the diodes includes one of a module diode, a surface mount diode, and an axial diode.

[0011] In one embodiment, each of the junction boxes further includes a box body for providing an accommodation space for the first diode and the second diode.

[0012] In one embodiment, the box body includes a polyphenylene ether box body or a polycarbonate box body.

[0013] Second, the present application provides a photovoltaic system, including:

[0014] A photovoltaic module;

[0015] The photovoltaic module junction box as described above, and the photovoltaic module junction box is connected to the photovoltaic module.

[0016] In one embodiment, the photovoltaic module includes a first battery unit, a second battery unit, and a third battery unit; the positive junction box of the photovoltaic module junction box is connected to the first battery unit, the middle junction box of the photovoltaic module junction box is connected to the second battery unit, and the negative junction box of the photovoltaic module junction box is connected to the third battery unit.

[0017] For the above photovoltaic module junction box and photovoltaic system, the photovoltaic module junction box includes a positive junction box, a middle junction box, and a negative junction box. Each junction box includes a first diode and a second diode, and the anode of the first diode is connected to the cathode of the second diode; wherein, the anodes of the first diodes in each junction box are connected to the jumper nodes in the first battery group and the second battery group in each battery unit through jumpers in a one-to-one correspondence; the jumper node is the series connection node of the first battery string and the second battery string. Each battery unit includes a first battery group and a second battery group, that is, the reverse bias voltage borne by each diode during operation is 1 / 6 of the open-circuit voltage. Compared with the prior art where each diode bears 1 / 3 of the open-circuit voltage, the present application can reduce it by half. Therefore, the thermal runaway ability of each diode in the junction box can be greatly improved, and the reliability and safety of the photovoltaic junction box can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the following will briefly introduce the drawings required for use in the description of the embodiments of the present application or the related art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0019] Figure 1 Schematic diagram of the connection between a photovoltaic module junction box and a photovoltaic module in an embodiment of the present application;

[0020] Figure 2 Schematic diagram of the structure of a photovoltaic module junction box in an embodiment of the present application.

[0021] Explanation of the reference numerals in the drawings:

[0022] Positive junction box: 110; Intermediate junction box: 120; Negative junction box: 130; First diode: 111; Second diode: 112; Jumper wire: 113; Conductive sheet: 114; Box body: 115; Through hole: 1141; Battery unit: 210; First battery group: 211; First battery string: 2111; Second battery string: 2112; Second battery group: 212. Specific embodiments

[0023] To make the above objects, features, and advantages of the present application more obvious and understandable, the following will provide a detailed description of the specific embodiments of the present application in conjunction with the drawings. Many specific details are set forth in the following description to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein. Those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0024] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0026] In this application, unless otherwise clearly defined and limited, terms such as "installed", "connected", "linked", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal connection of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0027] In this application, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature is at a higher level than the second feature in terms of horizontal height. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature is at a lower level than the second feature in terms of horizontal height.

[0028] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it may be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation.

[0029] The photovoltaic module junction box in this application is used to connect photovoltaic modules to ensure that the photovoltaic modules safely output electricity to the outside. The photovoltaic modules in this embodiment include a plurality of battery units, which are connected in parallel among the battery units, and each battery unit includes a first battery group and a second battery group, the first battery group and the second battery group are connected in parallel, and each battery group includes a first battery string and a second battery string connected in series.

[0030] In one embodiment, refer to the attached Figure 1 , attached Figure 1The figure shows a schematic diagram of the connection between the photovoltaic module junction box and the photovoltaic module in this embodiment. The photovoltaic module junction box in this embodiment includes a positive junction box 110, an intermediate junction box 120, and a negative junction box 130. Each junction box includes a first diode 111 and a second diode 112, and the anode of the first diode 111 is connected to the cathode of the second diode 112. Among them, the anodes of the first diodes 111 in each junction box are respectively connected to the jumper nodes P in the first battery group 211 and the second battery group 212 in each battery unit 210 through jumpers 113; the jumper node P is the series connection node of the first battery string 2111 and the second battery string 2112.

[0031] Exemplarily, taking the positive junction box 110 as an example, the connection contact point of the first diode 111 and the second diode 112 in the positive junction box 110 is connected to the series connection node between the first battery string 2111 and the second battery string 2112 in the first battery group 211 through a jumper 113.

[0032] It can be understood that thermal runaway (thermal escape) is one of the most dangerous failure modes for diodes working outdoors for a long time. The most critical factor affecting it is the reverse cut-off ability of the diode at high temperatures. The test scheme for this mode is to apply 1.25Isc for 50 minutes at 75°C. After the diode temperature stabilizes, switch the reverse voltage within 10 ms, and observe the temperature and reverse leakage of the diode. If both show a downward trend, the test passes. The reverse ability of the diode will decrease significantly at high temperatures. The voltage that the diode withstands in reverse in this scheme is only 1 / 2 of the conventional scheme, which will greatly improve the thermal escape ability of the diode and enhance the reliability and safety.

[0033] When there is shading in the first battery string 2111 of the first battery pack 211 in the target battery cell 210, the conduction line of the junction box connecting the photovoltaic module to the target battery pack is the connection line formed by the second battery string 2112 in the first battery pack 211, the diode connected to the second battery string 2112 in the first battery pack 211, and the jumper 113; the target battery cell 210 is any one of a plurality of battery cells 210. Exemplarily, taking a case where a certain battery in the first battery string 2111 of the first battery pack 211 in the battery cell 210 connected to the positive junction box 110 is shaded as an example, the current direction in the first battery pack 211 at this time is: the second battery string 2112 - the jumper 113 - the first diode 111 in the positive junction box 110. At this time, the power loss is 1 / 12, while the power loss of the prior art solution reaches 1 / 6; when a certain battery in the second battery string 2112 of the first battery pack 211 is shaded, the current direction in the first battery pack 211 at this time is: the second diode 112 in the positive junction box 110 - the jumper 113 - the first battery string 2111. At this time, the power loss is 1 / 12, while the power loss of the prior art solution is 1 / 6.

[0034] When there is shading in both the first battery string 2111 and the second battery string 2112 of the first battery pack 211 in the target battery cell 210, the conduction line of the junction box connecting the photovoltaic module to the target battery pack is the connection line formed by the first diode 111 and the second diode 112 connected to the first battery string 2111 and the second battery string 2112 of the first battery pack 211 in the target battery cell 210.

[0035] It can be seen that when a certain diode fails and is damaged, the corresponding battery string in the conventional solution will no longer be protected by the bypass diode, and the shaded battery cells will have a hot spot phenomenon, generating a large amount of heat, resulting in power loss, and there is a risk of burning the entire module; while this situation will not occur when one diode is damaged in this solution, and it will only occur when two diodes between two strings of batteries are damaged simultaneously. Because in this actual example, the reverse bias voltage borne by each diode during operation is 1 / 6 of the open-circuit voltage, compared with 1 / 3 of the open-circuit voltage borne by each diode in the prior art, the present application can reduce it by half. Therefore, it can greatly improve the thermal escape ability of each diode in the junction box and improve the reliability and safety of the photovoltaic junction box.

[0036] In one embodiment, each junction box further includes a conductive sheet, and the conductive sheet is connected to each diode in the same junction box for electrically connecting each diode and the bus bar of the photovoltaic module.

[0037] In this embodiment, the diodes in the same junction box of the conductive sheet are connected, and each diode is electrically connected to the bus bar of the photovoltaic module, so that the current generated by the photovoltaic module can be effectively transmitted to the outside world, and the normal operation of the entire photovoltaic system can be protected in the case of cell failure or shading. It can be understood that during the process of connecting the diode and the bus bar, methods such as resistance welding are required to ensure a firm connection, so as to avoid the reduction of current transmission efficiency or even equipment damage caused by poor connection. At the same time, a good connection can also reduce the contact resistance and further reduce the energy loss. In this embodiment, the electrical connection between each diode and the photovoltaic module is realized through the conductive sheet, which not only ensures the effective transmission of current, but also provides guarantee for the stability and reliability of the photovoltaic system.

[0038] In one embodiment, the conductive sheet is further provided with through holes, so that the bus bar of the photovoltaic module is electrically connected to each diode through the through holes. In this embodiment, the electrical connection between the bus bar and each diode is realized by arranging through holes in the conductive sheet, which can shorten the current transmission path and reduce the high impedance caused by too long transmission path. It helps to reduce electromagnetic interference, makes the distribution of current in the bus bar more uniform, and improves the integrity of signal transmission.

[0039] In one embodiment, the number of conductive sheets is one, and the number of through holes is three. In this embodiment, one conductive sheet is arranged in one junction box, and three through holes are arranged. That is, one through hole is respectively arranged near both ends of the first diode and the second diode connected in series, and one through hole is arranged near the connection node of the first diode and the second diode, which can reduce the cost and make reasonable use of the space of the junction box.

[0040] In one embodiment, the diode chip in each diode includes one of a Schottky planar diode chip, a Schottky trench diode chip, and a MOSFET (metal oxide semiconductor field effect transistor) diode chip.

[0041] Among them, the Schottky planar diode chip is formed by the contact of a metal and a semiconductor material (such as silicon). The planar diode chip form means that this contact is flat on the surface of the diode chip. It has a low forward voltage drop and a fast switching speed. Therefore, the Schottky planar diode chip is suitable for applications with fast response and high efficiency. The Schottky trench diode chip has a trench pattern etched on the semiconductor surface, which increases the effective contact area of the device and can provide a wider safe operating range. Therefore, the Schottky trench diode chip can operate stably at higher ambient temperatures. The MOSFET diode chip is a device used to amplify or switch electronic signals. By constructing a gate on a silicon wafer to control the flow of current, it has a high input impedance and a low on-resistance, and is suitable for applications such as high-speed switching and high-efficiency management. In this embodiment, any one of the Schottky planar diode chip, the Schottky trench diode chip, and the MOSFET diode chip can be selected for packaging according to actual needs.

[0042] In one embodiment, the packaging structure of each diode includes one of a module diode, a surface mount diode, and an axial diode.

[0043] It can be understood that the specific packaging method of the diode packaging structure needs to comprehensively consider the structure of the photovoltaic module connected thereto. For example, electrical performance requirements, thermal management requirements, mechanical stability requirements, etc. need to be considered. For example, the surface mount packaged diode, due to its small size, is suitable for applications with low to medium current and voltage. The larger volume of the axial packaged diode helps with heat dissipation and can be suitable for applications with higher heat dissipation requirements. The module diode is designed for high current and high voltage applications and can provide strong electrical performance. Therefore, in actual applications, multiple packaging methods can be flexibly selected in combination to improve the performance of the photovoltaic module junction box.

[0044] In one embodiment, each junction box further includes a box body for providing a receiving space for the first diode and the second diode to further prevent each diode from being damaged by external forces.

[0045] In one embodiment, the box body includes a polyphenylene ether box body or a polycarbonate box body.

[0046] The polyphenylene ether box body refers to a box body prepared from polyphenylene ether, and the polycarbonate shell refers to a box body prepared from polycarbonate. In this embodiment, the box body in the photovoltaic module junction box can be a box body with high stability such as a polyphenylene ether box body or a polycarbonate box body, which is used to ensure the heat resistance, water resistance, and dimensional stability of each junction box body.

[0047] In one embodiment, refer to the appendix Figure 2 , appendix Figure 2The structural schematic diagram of the photovoltaic module junction box in this embodiment is shown. The photovoltaic module junction box in this embodiment includes a positive junction box 110, an intermediate junction box 120, and a negative junction box 130. Each junction box includes a conductive sheet 114, a box body 115, a first diode 111, and a second diode 112. The conductive sheet 114 covers the first diode 111 and the second diode 112 and is disposed on the surfaces of the first diode 111 and the second diode 112. Three through holes 1141 are provided in the conductive sheet 114. Two of the through holes 1141 are arranged close to the anode and cathode of the first diode 111, and the third through hole 1141 is arranged close to the anode of the second diode 112.

[0048] In one embodiment, the present application further provides a photovoltaic system. The photovoltaic system in this embodiment includes a photovoltaic module and the photovoltaic module junction box in any of the above embodiments, and the photovoltaic module junction box is connected to the photovoltaic module.

[0049] In one embodiment, the photovoltaic module includes a first battery unit, a second battery unit, and a third battery unit; the positive junction box of the photovoltaic module junction box is connected to the first battery unit, the intermediate junction box of the photovoltaic module junction box is connected to the second battery unit, and the negative junction box of the photovoltaic module junction box is connected to the third battery unit.

[0050] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0051] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A photovoltaic module junction box, characterized in that: The photovoltaic module includes a plurality of battery units, each of which is connected in parallel, and each of the battery units includes a first battery group and a second battery group, the first battery group and the second battery group are connected in parallel, and each battery group includes a first battery string and a second battery string connected in series; the photovoltaic module junction box includes a positive junction box, an intermediate junction box and a negative junction box, each junction box includes a first diode and a second diode, and the anode of the first diode is connected to the cathode of the second diode; Among them, the anode of the first diode in each junction box is connected to the jumper node in the first battery group and the second battery group in each battery unit through a jumper one by one; the jumper node is the series connection node of the first battery string and the second battery string.

2. The photovoltaic module junction box according to claim 1, characterized in that: Each of the junction boxes further comprises a conductive sheet, which is connected to each diode in the same junction box and is used to electrically connect each of the diodes and a bus bar of the photovoltaic module.

3. The photovoltaic module junction box according to claim 2, characterized in that: The conductive sheet is also provided with through holes, so that the bus bar of the photovoltaic module is electrically connected to each of the diodes through the through holes.

4. The photovoltaic module junction box according to claim 3, characterized in that: The number of the conductive sheet is one, and the number of the through holes is three.

5. The photovoltaic module junction box according to any one of claims 1 to 4, characterized in that: The diode chip in each of the diodes includes one of a Schottky planar diode chip, a Schottky trench diode chip and a MOSFET diode chip.

6. The photovoltaic module junction box according to any one of claims 1 to 4, characterized in that: The packaging structure of each diode includes one of a module diode, a surface mount diode and an axial diode.

7. The photovoltaic module junction box according to claim 1, characterized in that: Each of the junction boxes further comprises a box body, which is used to provide a housing space for the first diode and the second diode.

8. The photovoltaic module junction box according to claim 7, characterized in that: The box body includes a polyphenylene ether box body or a polycarbonate box body.

9. A photovoltaic system, characterized in that: include: Photovoltaic panels; The photovoltaic module junction box according to any one of claims 1 to 8, wherein the photovoltaic module junction box is connected to the photovoltaic module.

10. The photovoltaic system according to claim 9, characterized in that: The photovoltaic assembly includes a first battery unit, a second battery unit and a third battery unit; the positive junction box of the photovoltaic assembly junction box is connected to the first battery unit, the middle junction box of the photovoltaic assembly junction box is connected to the second battery unit, and the negative junction box of the photovoltaic assembly junction box is connected to the third battery unit.

Images