Photovoltaic junction box

Abstract

The invention belongs to the technical field of solar photovoltaics, and particularly discloses a photovoltaic junction box. According to the photovoltaic junction box provided by the invention, the pins of the diodes are welded with the welding parts of the heat dissipation pieces, and heat generated when the diodes work can be dissipated through the heat dissipation pieces; the pins of the diodes are welded with the heat dissipation piece, so that the bus bar welding surfaces are formed on the surfaces of the pins of the diodes, and the bus bars are welded with the bus bar welding surfaces, so that direct conductive connection between the bus bars and the pins of the diodes is realized; the current flows through the first bus bar, the first pin of the diode, the diode, the second pin of the diode and the second bus bar in sequence, the intermediate medium through which the current flows is reduced, the loss of electric energy is further reduced, in addition, the bus bars are directly connected with the pins of the diode, heat generated by the diode can be dissipated through the bus bars, and the service life of the diode is prolonged. Therefore, the overall heat dissipation efficiency of the photovoltaic junction box is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar photovoltaics, and particularly to a photovoltaic junction box. Background Art

[0002] A photovoltaic junction box is a connector between a photovoltaic cell array composed of photovoltaic cell modules and a photovoltaic cell charging and control device. Its main function is to connect and protect solar photovoltaic modules, connect the electricity generated by photovoltaic cells to external circuits, and export the electrical energy generated by photovoltaic cell modules through cables.

[0003] Traditional photovoltaic junction boxes usually include parts such as a base, terminals, diodes, and a box cover. The terminals are welded to the pins of the diodes, then the diodes with welded terminals are placed into the base, then the bus bars are welded to the terminals, and finally glue is poured into the base, and the box cover is buckled onto the base. In the photovoltaic junction box of the prior art, a terminal is required as an intermediate conductive medium between the diode and the bus bar. The current needs to flow through the first bus bar, the first terminal, the first pin of the diode, the second terminal, and the second bus bar in sequence. There are many intermediate media through which the current flows, resulting in more power loss. Moreover, there are many welding positions, and the risk of false welding is high. The internal heat dissipation efficiency of the photovoltaic junction box is poor. Summary of the Invention

[0004] The purpose of the present invention is to provide a photovoltaic junction box, which reduces the power loss of the photovoltaic junction box and improves the internal heat dissipation efficiency of the photovoltaic junction box.

[0005] To achieve this purpose, the present invention adopts the following technical solutions:

[0006] A photovoltaic junction box, comprising:

[0007] A diode;

[0008] A heat dissipation member, the heat dissipation member includes a welding portion, the pins of the diode are welded to the welding portion, and a bus bar welding surface for welding with a bus bar 4 is formed on the surface of the pins of the diode.

[0009] As an optional technical solution of the above photovoltaic junction box, the welding portion includes a welding plate, and the pins of the diode are welded to the surface of the welding plate.

[0010] As an optional technical solution of the above photovoltaic junction box, a plurality of grooves are provided at intervals on one surface of the welding plate for welding with the pins of the diode.

[0011] As an optional technical solution of the above photovoltaic junction box, first heat dissipation plates are provided on both opposite sides of the welding portion, and the first heat dissipation plates extend toward the side away from the welding surface of the welding portion and the pins of the diode.

[0012] As an alternative technical solution of the above photovoltaic junction box, the heat dissipation member further includes a connecting portion, one end of the connecting portion is connected to one end of the welding portion, second heat dissipation plates are provided on both opposite sides of the connecting portion, the second heat dissipation plates are arranged at an angle with the connecting portion, and the second heat dissipation plates extend in a direction away from the connecting portion.

[0013] As an alternative technical solution of the above photovoltaic junction box, the photovoltaic junction box further includes a base, the heat dissipation member is arranged in the base, and the connecting portion is attached to the bottom wall of the base;

[0014] And / or, the projected area of the connecting portion on the bottom wall of the base is larger than the projected area of the welding portion on the bottom wall of the base.

[0015] As an alternative technical solution of the above photovoltaic junction box, a third heat dissipation plate is provided at the other end of the connecting portion, the third heat dissipation plate is arranged at an angle with the connecting portion, and the third heat dissipation plate extends in a direction away from the connecting portion.

[0016] As an alternative technical solution of the above photovoltaic junction box, the photovoltaic junction box further includes a cable connector, one end of the cable connector is placed between the welding portion and the pin of the diode, the cable connector is welded to the welding portion and the pin of the diode respectively, and the other end of the cable connector is electrically connected to a cable.

[0017] As an alternative technical solution of the above photovoltaic junction box, one end of the cable connector is a plurality of connecting plates arranged at intervals, and the connecting plates are placed between the welding portion and the pin of the diode.

[0018] As an alternative technical solution of the above photovoltaic junction box, the cable connector includes a first plate portion, a second plate portion and a third plate portion connected in sequence, the first plate portion is the plurality of connecting plates, the first plate portion is arranged between the welding portion and the pin of the diode, the second plate portion is arranged higher than the first plate portion, the third plate portion is arranged higher than the second plate portion, and the third plate portion is electrically connected to the cable.

[0019] As an alternative technical solution of the above photovoltaic junction box, the photovoltaic junction box further includes a base, the diode and the heat dissipation member are arranged in the base, a through hole is provided at the bottom of the base, the through hole is used for the bus bar to pass through and is welded to the welding surface of the bus bar, and insulating glue is poured into the base.

[0020] Advantages of the present invention:

[0021] For the photovoltaic junction box provided by the present invention, the pin of the diode is welded to the welding part of the heat sink. When the diode is working, the heat generated can be transferred to the heat sink through the pin of the diode and dissipated through the heat sink. The pin of the diode is welded to the heat sink to form a bus bar welding surface on the surface of the pin of the diode. The bus bar is welded to the bus bar welding surface to achieve direct electrical connection between the bus bar and the pin of the diode, so that the current flows through the first bus bar, the first pin of the diode, the diode, the second pin of the diode, and the second bus bar in sequence. The intermediate medium through which the current flows is reduced, thereby reducing the power loss. In addition, the bus bar is directly connected to the pin of the diode, and the heat generated by the diode can also be dissipated from the photovoltaic junction box through the bus bar, playing a role in efficient heat dissipation, thereby improving the overall heat dissipation efficiency of the photovoltaic junction box. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is an exploded view of a positive-type photovoltaic junction box provided by an embodiment of the present invention;

[0023] Figure 2 is an axonometric view of the internal structure of the base provided by an embodiment of the present invention;

[0024] Figure 3 is a schematic diagram of the connection structure of the heat sink, diode and cable connector provided by an embodiment of the present invention;

[0025] Figure 4 is a schematic diagram of the connection structure of the heat sink, diode and cable connector when the bus bar welding surface is not formed provided by an embodiment of the present invention;

[0026] Figure 5 is a cross-sectional view of the internal structure of the base provided by an embodiment of the present invention;

[0027] Figure 6 is a schematic diagram of the structure in which the base is filled with insulating glue provided by an embodiment of the present invention;

[0028] Figure 7 is a schematic diagram of the structure in which the base is fastened with a lid provided by an embodiment of the present invention;

[0029] Figure 8 is a schematic diagram of a structure of the heat sink provided by an embodiment of the present invention;

[0030] Figure 9 is another schematic diagram of a structure of the heat sink provided by an embodiment of the present invention;

[0031] Figure 10 is a schematic diagram of the connection structure of the welding part, cable connector and diode provided by an embodiment of the present invention;

[0032] Figure 11It is a schematic structural diagram of a cable connector provided by an embodiment of the present invention;

[0033] Figure 12 It is an exploded view of an intermediate - type photovoltaic junction box provided by an embodiment of the present invention;

[0034] Figure 13 It is an exploded view of a negative - type photovoltaic junction box provided by an embodiment of the present invention.

[0035] In the figure:

[0036] 1. Diode; 2. Heat sink; 3. Busbar welding surface; 4. Busbar; 5. Cable connector; 6. Cable; 7. Base; 8. Lid; 9. Pressing buckle; 10. Insulating glue;

[0037] 21. Welding part; 211. Groove; 22. First heat - dissipation plate; 23. Connecting part; 24. Second heat - dissipation plate; 25. Third heat - dissipation plate;

[0038] 51. First plate part; 511. Connecting plate; 52. Second plate part; 53. Third plate part. Detailed implementation manners

[0039] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only for explaining the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only parts related to the present invention are shown in the drawings, rather than all structures.

[0040] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above - mentioned terms in the present invention can be understood according to specific situations.

[0041] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "over", and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "under", and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the horizontal height of the first feature is lower than that of the second feature.

[0042] In the description of this embodiment, the orientation or positional relationships such as "upper", "lower", "right", etc. are based on the orientation or positional relationships shown in the drawings. They are only for the convenience of description and simplifying the operations, 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. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0043] As Figures 1 to 4 shown, this embodiment provides a photovoltaic junction box, which includes a diode 1 and a heat sink 2. The heat sink 2 includes a welding portion 21. The pins of the diode 1 are welded to the welding portion 21, and a bus bar welding surface 3 for welding with a bus bar 4 is formed on the surface of the pins of the diode 1. The pins of the diode 1 are welded to the welding portion 21 of the heat sink 2. When the diode 1 works, the heat generated can be transferred to the heat sink 2 through the pins of the diode 1 and dissipated through the heat sink 2. The pins of the diode 1 are welded to the heat sink 2 to form a bus bar welding surface 3 on the surface of the pins of the diode 1. The bus bar 4 is welded to the bus bar welding surface 3, realizing the direct conductive connection between the bus bar 4 and the pins of the diode 1, so that the current flows through the first bus bar 4, the first pin of the diode 1, the diode 1, the second pin of the diode 1, and the second bus bar 4 in sequence. The intermediate medium through which the current flows is reduced, thereby reducing the power loss. In addition, the bus bar 4 is directly connected to the pins of the diode 1, and the heat generated by the diode 1 can also be dissipated from the photovoltaic junction box through the bus bar 4, playing a role in efficient heat dissipation, thus improving the overall heat dissipation efficiency of the photovoltaic junction box.

[0044] Optionally, the pins of the diode 1 are welded to the welding portion 21 by resistance welding to form the bus bar welding surface 3, or the pins of the diode 1 can also be welded to the welding portion 21 by soldering to form the bus bar welding surface 3, or the pins of the diode 1 can also be connected to the welding portion 21 by riveting. Solder is added to the bus bar welding surface 3, and the bus bar 4 can be welded to the bus bar welding surface 3 by soldering or by laser welding.

[0045] The diode 1 has two pins. One heat sink 2 and one bus bar 4 are respectively arranged corresponding to each pin of the diode 1, so that the current flows through the first bus bar 4, the first pin of the diode 1, the diode 1, the second pin of the diode 1, and the second bus bar 4 in sequence.

[0046] As Figure 2 and Figure 5As shown, the photovoltaic junction box further includes a base 7. The diode 1 and the heat dissipation component 2 are arranged inside the base 7. A through hole is provided at the bottom of the base 7. One end of the bus bar 4 passes through the through hole and is connected to the bus bar welding surface 3. Specifically, one end of the bus bar 4 is bent into a U-shaped structure. The bus bar 4 is placed on the upper surface of the bus bar welding surface 3 and is welded to the bus bar welding surface 3 by soldering, realizing the electrical connection between the bus bar 4 and the pin of the diode 1, and further realizing the electrical connection between the photovoltaic junction box and the photovoltaic cell.

[0047] As Figure 6 shown, insulating glue 10 is poured into the base 7. The heat generated when the diode 1 works can be dissipated to the outside of the photovoltaic junction box through the heat dissipation component 2, the insulating glue 10, and the side wall of the base 7 in sequence. Moreover, the insulating glue 10 also plays a role in fixing the diode 1, the heat dissipation component 2, and the bus bar 4.

[0048] As Figure 7 shown, the photovoltaic junction box further includes a box cover 8. After the insulating glue 10 is poured into the base 7, the box cover 8 is buckled onto the base 7, playing a role in protecting the insulating glue 10 inside the base 7.

[0049] In order to improve the connection strength between the pin of the diode 1 and the welding part 21, in some embodiments, the welding part 21 includes a welding plate, and the pin of the diode 1 is welded to the surface of the welding plate. During resistance welding, the molten metal liquid flows into the groove 211 and fills the groove 211. After the metal liquid in the groove 211 solidifies, it is connected to the pin of the diode 1, improving the connection reliability between the pin of the diode 1 and the welding part 21. Or during soldering, the molten solder flows into the groove 211 and fills the groove 211. After the solder in the groove 211 solidifies, it is connected to the pin of the diode 1, improving the connection reliability between the pin of the diode 1 and the welding part 21.

[0050] Further optionally, a plurality of grooves 211 are arranged at intervals on the surface of the welding plate for welding with the pin of the diode 1. During resistance welding, the molten metal liquid flows into the groove 211, or during soldering, the molten solder flows into the groove 211, further improving the connection strength between the pin of the diode 1 and the welding part 21.

[0051] As Figure 8 and Figure 9As shown in the figure, first heat dissipation plates 22 are provided on both sides opposite to the welding part 21. The first heat dissipation plates 22 extend towards the side away from the welding surface of the welding part 21 and the pin of the diode 1. When the diode 1 works, the heat generated is transferred to the first heat dissipation plates 22 through the pins of the diode 1 and the bus bar welding surface 3, and then dissipated to the outside through the insulating glue 10 and the side wall of the base 7, further improving the heat dissipation performance of the photovoltaic junction box. Optionally, the first heat dissipation plates 22 are connected to the edges of the welding plates of the welding part 21, and the first heat dissipation plates 22 are perpendicular to the welding plates, so as to facilitate the installation of the heat dissipation part 2 into the base 7 without affecting the connection between the pins of the diode 1 and the welding plates. In addition, the first heat dissipation plates 22 also play a role in shielding. During the resistance welding process, the first heat dissipation plates 22 can block the molten metal liquid from flowing to both sides, reducing the loss of the metal liquid and ensuring the effective area of the bus bar welding surface 3. Or during the soldering process, the first heat dissipation plates 22 can block the molten solder from flowing to both sides, reducing the loss of the solder and ensuring the effective welding between the pins of the diode 1 and the welding part 21, or the effective welding between the bus bar welding surface 3 and the bus bar 4.

[0052] The heat dissipation part 2 further includes a connecting part 23. One end of the connecting part 23 is connected to one end of the welding part 21. Second heat dissipation plates 24 are provided on both sides opposite to the connecting part 23. The second heat dissipation plates 24 are arranged at an angle with the connecting part 23 and extend towards the direction away from the connecting part 23. When the diode 1 works, the heat generated can also be dissipated through the connecting part 23 and the two second heat dissipation plates 24. The heat can be dissipated to the outside through the connecting part 23, the insulating glue 10 and the bottom wall of the base 7. The heat can also be dissipated to the outside through the connecting part 23, the two second heat dissipation plates 24, the insulating glue 10 and the side wall of the base 7, further improving the heat dissipation performance of the photovoltaic junction box. The connecting part 23 can be a plate-like structure. One end of the connecting part 23 is connected to one end of the welding plate, and the area of the connecting part 23 is larger than that of the welding plate to maximize the heat dissipation area as much as possible. The second heat dissipation plates 24 are connected to the edges of the connecting part 23, and the second heat dissipation plates 24 are perpendicular to the connecting part 23, so as to facilitate the installation of the heat dissipation part 2 into the base 7.

[0053] The heat dissipation part 2 is arranged in the base 7, and the connecting part 23 is attached to the bottom wall of the base 7. The connecting part 23 serves as the main heat dissipation part of the heat dissipation part 2. The connecting part 23 is arranged close to the bottom wall of the base 7 to improve the heat dissipation efficiency.

[0054] Optionally, the projected area of the connecting part 23 on the bottom wall of the base 7 is larger than the projected area of the welding part 21 on the bottom wall of the base 7, and the connecting part 23 undertakes the main heat dissipation function.

[0055] Further optionally, a third heat dissipation plate 25 is provided at the other end of the connecting portion 23. The third heat dissipation plate 25 is disposed at an angle with the connecting portion 23 and extends in a direction away from the connecting portion 23. The heat generated when the diode 1 operates can be dissipated to the outside through the connecting portion 23, the third heat dissipation plate 25, the insulating glue 10, and the side wall of the base 7, further improving the heat dissipation performance of the photovoltaic junction box. The third heat dissipation plate 25 can be connected to the edge of the connecting portion 23, and the third heat dissipation plate 25 is perpendicular to the connecting portion 23 to facilitate the installation of the heat dissipation member 2 into the base 7.

[0056] As Figure 2 , Figure 3 , Figure 5 and Figure 10 shown, the photovoltaic junction box further includes a cable connector 5. One end of the cable connector 5 is placed between the welding portion 21 and the pin of the diode 1. The cable connector 5 is welded to the welding portion 21 and the pin of the diode 1 respectively, and the other end of the cable connector 5 is electrically connected to a cable 6. The cable 6 is used to connect to a circuit outside the photovoltaic junction box, thereby realizing the connection between the photovoltaic junction box and the external circuit. The cable 6 can be welded to the other end of the cable connector 5 by resistance welding or soldering.

[0057] One end of the cable connector 5 is a plurality of connecting plates 511 arranged at intervals. The connecting plates 511 are placed between the welding portion 21 and the pin of the diode 1. After the solder melts, it can fill the groove 211 and the space between the connecting plates 511 and the pin of the diode 1, improving the connection reliability between the welding portion 21, the connecting plates 511, and the pin of the diode 1. Optionally, the connecting plates 511 are inserted into the groove 211 of the welding portion 21.

[0058] Continuing to refer to Figure 10 shown, the groove 211 can be divided into two types. The inner diameter of one type of groove 211 is larger than that of the other type of groove 211, and the groove 211 with a larger inner diameter matches the size of the connecting plates 511.

[0059] As Figure 11As shown in the figure, the cable connector 5 includes a first plate portion 51, a second plate portion 52, and a third plate portion 53 that are connected in sequence. The first plate portion 51 is a plurality of connecting plates 511. The first plate portion 51 is disposed between the welding portion 21 and the pin of the diode 1. The second plate portion 52 is disposed higher than the first plate portion 51, and the third plate portion 53 is disposed higher than the second plate portion 52. The third plate portion 53 is electrically connected to the cable 6. The first plate portion 51 and the third plate portion 53 are set at different heights to facilitate the connection of the cable connector 5 to the welding plate and the cable 6. A convex rib is provided on one side of the third plate portion 53 connected to the cable 6 to improve the connection stability between the cable 6 and the third plate portion 53. The first plate portion 51, the second plate portion 52, and the third plate portion 53 are integrally connected structures, and the first plate portion 51, the second plate portion 52, and the third plate portion 53 with different heights are formed by a stamping process.

[0060] See Figure 1 As shown in the figure, the cable 6 passes through the side wall of the base 7. One end of the cable 6 is placed inside the base 7 and connected to the cable connector 5, and the other end of the cable 6 is placed outside the base 7 for connection to an external circuit. An opening is provided on the side wall of the base 7 for the cable 6 to pass through. A wire pressing buckle 9 is also connected to the base 7. The wire pressing buckle 9 is connected to the outer side wall of the base 7 to cooperate with the base 7 to fix the cable 6 on the base 7, preventing the cable 6 from being dragged and becoming desoldered from the cable connector 5.

[0061] There are three types of photovoltaic junction boxes, namely the positive junction box, the intermediate junction box, and the negative junction box.

[0062] As Figure 12 As shown in the figure, for the intermediate junction box, the junction box does not need to be provided with a cable 6. In order to improve the heat dissipation performance of the junction box, the two heat dissipation members 2 in the junction box both include a first heat dissipation plate 22, a second heat dissipation plate 24, and a third heat dissipation plate 25.

[0063] Figure 1 is an exploded view of the positive junction box, Figure 13 is an exploded view of the negative junction box. As Figure 1 and Figure 13 As shown in the figure, for the positive junction box and the negative junction box, the junction box needs to be provided with a cable 6. One of the heat dissipation members 2 in the junction box includes a first heat dissipation plate 22, a second heat dissipation plate 24, and a third heat dissipation plate 25 to improve the heat dissipation performance of the junction box. The other heat dissipation member 2 includes a first heat dissipation plate 22 and a second heat dissipation plate 24. The third heat dissipation plate 25 is not provided at one end of the connecting portion 23 opposite to the welding portion 21. One end of the cable connector 5 passes through the connecting portion 23 and is inserted between the welding portion 21 and the pin of the diode 1, playing a role of avoiding for the setting of the cable connector 5.

[0064] The material of the above-mentioned heat dissipation component 2 is a heat-conducting material to improve the heat dissipation efficiency. In the present invention, the heat dissipation component 2 only plays the roles of heat dissipation and supporting the pins of the diode 1, and does not play the role of conducting electricity. Therefore, the heat dissipation component 2 can not only be made of copper material, but also be made of other materials with good heat dissipation effects such as steel material and aluminum material. Compared with the copper material, the material cost is lower, thereby reducing the production cost of the photovoltaic junction box. The cable connector 5 realizes the electrical connection between the cable 6 and the pins of the diode 1. Therefore, the material of the cable connector 5 is copper.

[0065] The heat dissipation component 2 is an integrally formed structure, and usually adopts a stamping process to form a welded part 21, a connecting part 23, a first heat dissipation plate 22 and a second heat dissipation plate 24 that are integrally connected, or forms a welded part 21, a connecting part 23, a first heat dissipation plate 22, a second heat dissipation plate 24 and a third heat dissipation plate 25 that are integrally connected.

[0066] Obviously, the above-mentioned embodiments of the present invention are only examples for clearly explaining the present invention, and are not limitations on the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A photovoltaic junction box, characterized in that: include: Diode (1); A heat sink (2), the heat sink (2) comprising a welding portion (21), the pins of the diode (1) being welded to the welding portion (21), and a busbar welding surface (3) for welding to a busbar (4) is formed on the surface of the pins of the diode (1).

2. The photovoltaic junction box according to claim 1, characterized in that: The welding portion (21) comprises a welding plate, and the pins of the diode (1) are welded to the surface of the welding plate.

3. The photovoltaic junction box according to claim 2, characterized in that: A plurality of grooves (211) are arranged at intervals on a surface of one side of the welding plate for welding with the pins of the diode (1).

4. The photovoltaic junction box according to claim 1, characterized in that: First heat sinks (22) are provided on opposite sides of the welding portion (21), and the first heat sinks (22) extend toward a side away from the welding portion (21) and the pin welding surface of the diode (1).

5. The photovoltaic junction box according to claim 4, characterized in that: The heat sink (2) further comprises a connecting portion (23), one end of the connecting portion (23) being connected to one end of the welding portion (21), and second heat sinks (24) being provided on opposite sides of the connecting portion (23), the second heat sink (24) being arranged at an angle to the connecting portion (23), and the second heat sink (24) extending in a direction away from the connecting portion (23).

6. The photovoltaic junction box according to claim 5, characterized in that: The photovoltaic junction box further comprises a base (7), the heat sink (2) is arranged in the base (7), and the connecting portion (23) is in contact with the bottom wall of the base (7); And / or, a projection area of ​​the connecting portion (23) on the bottom wall of the base (7) is greater than a projection area of ​​the welding portion (21) on the bottom wall of the base (7).

7. The photovoltaic junction box according to claim 5, characterized in that: A third heat dissipation plate (25) is provided at the other end of the connecting portion (23); the third heat dissipation plate (25) is arranged at an angle with the connecting portion (23), and the third heat dissipation plate (25) extends in a direction away from the connecting portion (23).

8. The photovoltaic junction box according to claim 1, characterized in that: The photovoltaic junction box further comprises a cable connector (5), one end of the cable connector (5) being disposed between the welding portion (21) and the pin of the diode (1), the cable connector (5) being respectively welded to the welding portion (21) and the pin of the diode (1); and the other end of the cable connector (5) being conductively connected to a cable (6).

9. The photovoltaic junction box according to claim 8, characterized in that: One end of the cable connector (5) is a plurality of spaced connection plates (511), and the connection plates (511) are placed between the welding portion (21) and the pins of the diode (1).

10. The photovoltaic junction box according to claim 9, characterized in that: The cable connector (5) comprises a first plate portion (51), a second plate portion (52) and a third plate portion (53) which are connected in sequence, wherein the first plate portion (51) is a plurality of connecting plates (511), the first plate portion (51) is arranged between the welding portion (21) and the pin of the diode (1), the second plate portion (52) is arranged higher than the first plate portion (51), the third plate portion (53) is arranged higher than the second plate portion (52), and the third plate portion (53) is conductively connected to the cable (6).

11. The photovoltaic junction box according to any one of claims 1 to 10, characterized in that: The photovoltaic junction box further comprises a base (7), the diode (1) and the heat sink (2) being arranged in the base (7), a through hole being provided at the bottom of the base (7), the through hole being used for the busbar (4) to be passed through and welded to the busbar welding surface (3), and the base (7) is filled with insulating glue (10).

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