JP2013171860A - Terminal box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce heat dissipation on a solar cell module side by forming an air layer between a terminal box and a solar cell module.SOLUTION: A terminal box 100 according to the present invention is mounted to a solar cell module as an output part of the solar cell module. The terminal box 100 comprises: plural terminal plates 2a, 2b, 2c; bypass diodes 4a, 4b; a housing 1; and a filling material. The housing 1 connecting the bypass diodes 4a, 4b and the terminal plates 2a, 2b, 2c houses a circuit configuration part 20 having the terminal plates 2a, 2b, 2c and the bypass diodes 4a, 4b inside. The circuit configuration part 20 is filled with the filling material, and the filling material has higher heat conductivity than that of the housing 1. A heat radiation hole is provided on a mounting face of the housing 1 in a region opposed to the bypass diodes 4a, 4b. The filling material is filled between the bypass diodes 4a, 4b and the solar cell module.

Description

  The present invention relates to a terminal box for electrically connecting solar battery panels to each other. In particular, the present invention relates to a terminal box that efficiently exhausts heat generated by a diode incorporated in the terminal box while ensuring flame retardancy and weather resistance required for the terminal box.

  A large number of solar cell modules are arranged on the roof of a house. A terminal box is attached to the back surface of the solar cell module. The solar cell module is composed of a plurality of panel modules. The terminal box is connected to each panel module constituting the solar cell module via a lead frame. The output of each panel module is put together in the terminal box and output from the output cable as the output of the solar cell module.

  A bypass diode is provided inside the terminal box. The bypass diode is for short-circuiting the current due to application of the reverse voltage from the lead frame to the output cable when the electromotive force of the solar cell panel decreases. In a solar cell panel, the electromotive force of the panel may decrease due to various reasons.

  For example, the electromotive force in a solar cell panel will fall because a part of cell which comprises a solar cell panel is damaged. In addition, when sunlight is blocked from a part of the cells constituting the solar cell panel by the shadow of the building, the electromotive force at the solar cell panel is reduced. In this case, the voltage generated in another solar cell panel that is normally generating power is applied in the form of a reverse voltage to the solar cell panel having a reduced electromotive force. This reduces the power generation amount of the entire solar cell panel. In addition, an abnormal heat generation phenomenon occurs in the solar cell panel in which the electromotive force is reduced.

  The bypass diode is provided to prevent such a decrease in the amount of power generation and the occurrence of abnormal heat generation. The bypass diode plays a role of bypassing the solar cell panel in which the electromotive force is reduced by short-circuiting the current when the reverse voltage is applied from one connection cable to the other connection cable.

  A large current flows through the bypass diode in the forward direction of the diode. As a result, the bypass diode generates heat violently and may exceed the proper operating temperature of the diode. In this case, problems such as deterioration of the function of the diode, destruction of the diode, and shortening of the life of the diode can be considered. For this reason, it is necessary to efficiently dissipate the generated heat so that the heat generated during the operation of the bypass diode does not exceed the proper operating temperature of the bypass diode.

  A technique for suppressing thermal deformation of a potting material when heat generated by a bypass diode or the like is radiated through the potting material is disclosed (for example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 2005-19833

  However, the heat generated in the terminal box itself is not efficiently discharged to the outside, and it does not solve problems such as a decrease in electromotive force and a shortened life of the diode.

  An object of the present invention is to provide a terminal box capable of efficiently discharging heat inside the terminal box to a solar cell module while ensuring flame retardancy and weather resistance required for the terminal box.

  A terminal box according to the present invention is a terminal box attached to a solar cell module as an output part of the solar cell module, and includes a plurality of terminal plates, a bypass diode connecting between the terminal plates, the terminal plate and the bypass diode. A housing that houses the circuit component having the above and a filler that is filled in the circuit component and has a higher thermal conductivity than the housing, and the mounting surface of the housing includes the bypass diode and A heat radiation hole is provided in the facing region, and the filler is filled between the bypass diode and the solar cell module.

  According to the terminal box according to the present invention, the heat inside the terminal box can be efficiently radiated to the panel solar cell module.

It is a disassembled perspective view which shows the structure of a terminal box. It is a block diagram which shows the inside of a terminal box. It is the perspective view seen from the attachment surface side of the terminal box. It is an enlarged view of the peripheral part of a thermal radiation hole seen from the attachment surface side of the terminal box. It is a figure which shows the example of adhesive application of a terminal box. It is a figure which shows the cross section of a terminal box.

Embodiment 1
FIG. 1 is an exploded perspective view of the terminal box 100 of the first embodiment. FIG. 2 is a configuration diagram of the terminal box 100 viewed from the opening 14 side. 1 and 2 show a state before the circuit component is filled with the filler 11 so that the circuit component can be seen. The terminal box 100 constitutes an output part of the solar cell module 8.

  As shown in FIGS. 1 and 2, the terminal box 100 includes a circuit configuration unit 20 and a housing 1. The circuit configuration unit 20 is housed in the housing 1 through the opening 14 of the housing 1. The circuit configuration unit 20 includes a terminal plate 2 and a bypass diode 4. The terminal box 100 shown in Embodiment 1 has two bypass diodes 4a and 4b. The terminal box 100 has three terminal plates 2a, 2b, and 2c.

  The bypass diode 4a has two terminals 41a and 42a. The bypass diode 4b has two terminals 41b and 42b. The terminal 41a is electrically connected to the terminal plate 2a. The terminal 42a is electrically connected to the terminal plate 2b. The terminal 41b is electrically connected to the terminal plate 2b. The terminal 42b is electrically connected to the terminal plate 2c. That is, the terminal plate 2a, the bypass diode 4a, the terminal plate 2b, the bypass diode 4b, and the terminal plate 2c are connected in series.

  The metal plate provided in the package portion 43a of the bypass diode 4a is attached so as to be in contact with the terminal plate 2a on the surface. The metal plate provided in the package part 43a has a function of a heat radiating surface. Thereby, the heat of the package part 43a is efficiently transmitted to the terminal board 2a. The metal plate provided in the package portion 43b of the bypass diode 4b is attached so as to be in contact with the terminal plate 2b on the surface. The metal plate provided in the package part 43b has a function of a heat radiating surface. Thereby, the heat of the package part 43b is efficiently transmitted to the terminal board 2b.

  The bypass diode 4 generates heat during operation. The terminals 41 and 42 of the bypass diode 4 are formed of a metal member having good thermal conductivity. However, since the terminals 41 and 42 have a small cross-sectional area, the thermal resistance is relatively large. For this reason, the heat generated by the bypass diode 4 is mainly transmitted from the heat radiation surface to the terminal plate 2. The ratio transmitted to the terminal plate 2 through the terminals 41 and 42 is small. Similarly, the heat generated by the bypass diode 4b is mainly transmitted to the terminal plate 2 via the heat radiating surface, and the ratio of heat transfer to the terminal plate 2 via the lead wire is small.

  One end of the output cable 5 is electrically connected to the terminal plate 2a. The output cable 5 is an output cable for the terminal box 100. The output cable 5 passes through a hole provided in the side surface of the housing 1 and is drawn out of the housing 1. The output cable 5 collectively outputs electricity generated by each panel module as an output of the solar cell module 8. The panel module is a module constituting the solar cell module 8. That is, a plurality of panel modules are assembled to constitute the solar electronic module 8.

  The lead frame 3 is a component that inputs the output of the panel module to the terminal box 100. That is, the terminal box 100 outputs the output of the plurality of panel modules from the output cable 5 together. At that time, the panel module to be connected is selected by the bypass diode 4. The lead frame 3a is connected to the terminal plate 2a. The lead frame 3b is connected to the terminal plate 2b. The lead frame 3c is connected to the terminal board 2c. Terminal plates 2a, 2b, and 2c have different potentials during operation. For this reason, at least the distance required between the terminal plates 2a, 2b, and 2c is required for the withstand voltage. In the first embodiment, the terminal plates 2a, 2b, and 2c are arranged in a line in the housing 1.

  Wiring holes 6a, 6b and 6c are provided on the surface of the housing 1 attached to the solar cell module 8 in the vicinity of the position where the lead frames 3a, 3b and 3c are connected to the terminal plates 2a, 2b and 2c. . One ends of the lead frames 3a, 3b, 3c are connected to the panel module. The lead frames 3a, 3b, 3c are drawn into the terminal box 100 from the wiring holes 6a, 6b, 6c and connected to the terminal plates 2a, 2b, 2c, respectively.

  The case of the terminal box 100 is composed of a housing 1 and a lid 9. The housing 1 is made of a material excellent in weather resistance and flame retardancy. The material of the housing 1 is, for example, ABS resin or modified PPO resin. The housing 1 has an opening 14 on the side facing the mounting surface of the solar cell module 8. The circuit configuration unit 20 is received from the opening 14 inside. The housing 1 is attached in close contact with the back surface of the solar cell module 8 with an adhesive 7 or the like.

  The lid 9 is made of a material excellent in weather resistance and flame retardancy, like the housing 1. The material of the lid 9 is, for example, ABS resin or modified PPO resin. The lid 9 is attached to the opening 14 of the housing 1. The lid 9 has a function of closing the opening 14. Although not shown, it is possible to further improve the flame retardancy by interposing an internal cover made of metal, for example, between the circuit component 20 and the lid 9.

  FIG. 3 is a perspective view seen from the attachment surface side in a state before the housing 1 is attached to the solar cell module 8. The housing 1 is provided with heat radiation holes 10a and 10b in addition to the wiring holes 6a, 6b and 6c.

  From the wiring holes 6a, 6b, and 6c, connection portions between the terminal plates 2a, 2b, and 2c and the lead frames 3a, 3b, and 3c can be seen. That is, the opening portions of the wiring holes 6a, 6b, 6c are provided up to the position of the connection portion between the terminal plates 2a, 2b, 2c and the lead frames 3a, 3b, 3c.

  Further, the rear surfaces of the terminal plates 2a and 2b can be seen from the heat radiation holes 10a and 10b. The back surfaces of the terminal plates 2a and 2b are surfaces opposite to the surfaces on which the bypass diodes 4a and 4b are attached. The back surfaces of the terminal plates 2a and 2b visible from the heat radiation holes 10a and 10b correspond to positions where the bypass diodes 4a and 4b are attached. That is, there are openings of the heat radiation holes 10a and 10b at positions corresponding to the portions where the package portions 43a and 43b of the terminal plates 2a and 2b are attached. The package part 43 is a heat generating part of the bypass diode 4.

  The heat source in the terminal box 100 is usually only the bypass diode 4. Of the heat radiation from the bypass diode 4, the ratio transmitted to the terminal plate 2 via the terminals 41 and 42 is small. The highest temperature portion of the terminal board 2 is a portion where the package portion 43 of the bypass diode 4 is attached. The heat radiation holes 10a and 10b are provided in portions where the package part 43 is attached to the terminal plates 2a and 2b. That is, it is provided at the highest temperature portion of the terminal plates 2a and 2b.

  The filler 11 that fills the circuit component 20 of the housing 1 is selected in consideration of flame retardancy, heat dissipation, and fillability. In consideration of these points, the filling material 11 is suitably a UL94-standard V0 grade two-component mixed type silicon potting material. The thermal conductivity is about 0.3 [W / m · K]. When the molding material used for the housing 1 is, for example, a modified PPO resin, the thermal conductivity is about 0.15 [W / m · K]. The thermal conductivity of the filler 11 is twice that of the housing 1. That is, the filler 11 has higher thermal conductivity than the housing 1.

  The heat radiation holes 10a and 10b are opened in the highest temperature portions of the terminal plates 2a and 2b. Then, the filler 11 having higher thermal conductivity than that of the housing 1 is filled between the terminal plates 2 a and 2 b and the solar cell module 8. Thereby, heat of the bypass diodes 4a and 4b can be efficiently transferred to the solar cell module 8. The temperature of the bypass diodes 4a and 4b can be kept low.

  FIG. 4 is an enlarged view of the periphery of the heat dissipation hole of FIG. Terminal plates 2a, 2b, and 2c have different potentials during operation. For this reason, a potential difference generating region 13a is generated between the terminal plate 2a and the terminal plate 2b. Further, a potential difference generation region 13b is generated between the terminal plate 2b and the terminal plate 2c. The heat radiation holes 10a and 10b are not provided at positions corresponding to the potential difference generation regions 13a and 13b.

  Terminal plates 2a, 2b, and 2c have different potentials. For this reason, if an insulation failure occurs between the terminal boards 2, abnormal heat generation may occur in the portion of the insulation failure. Since the heat radiating holes 10a and 10b are not located at positions corresponding to the potential difference generating regions 13a and 13b, respectively, the casing 1 surrounds the portion where abnormal heat is generated. Since the housing 1 is a material excellent in flame retardancy, there is a high possibility that ignition or the like can be avoided.

  The terminal plates 2a and 2b have a function of diffusing heat from the bypass diodes 4a and 4b. In order to efficiently transmit the heat generated by the bypass diodes 4a and 4b to the solar cell module 8, it is preferable that the distance between the terminal plates 2a and 2b and the bottom surface of the housing 1 is narrow. The bottom surface of the housing 1 is a surface attached to the solar cell module 8. However, when the viscosity of the filler 11 is high, the filler 11 may not be sufficiently filled around the heat radiation hole 10.

  Therefore, the terminal plates 2a and 2b are provided with holes 12 at positions corresponding to the heat radiation holes 10a and 10b. Further, since the terminal plate 2c has a narrow gap with the housing 1, a hole 12 may be provided. By providing the holes 12 in the terminal plate 2, the filler 11 can be easily filled in the heat radiation holes 10 a and 10 b even if the distance between the terminal plate 2 and the bottom surface of the housing 1 is narrow. Further, the filler 11 can be easily filled between the terminal plate 2 and the bottom surface of the housing 1 in the gap between the terminal plate 2 and the bottom surface of the housing 1.

  FIG. 5 is a view showing a position where the adhesive 7 on the back surface of the housing 1 is applied. The housing 1 is attached to the solar cell module 8 with an adhesive 7.

  As the filler 11, a two-component mixed type silicon potting material is employed. The two-component mixed type silicon potting material requires a certain amount of time to be cured. The filler 11 is filled after the housing 1 is attached to the solar cell module 8. The adhesive 7 is applied so that the filler 11 does not leak out from the gap between the casing 1 and the solar cell module 8 when the inside of the casing 1 is filled with the filler 11. The adhesive 7 is applied so as to surround the wiring holes 6a, 6b, 6c and the heat radiation holes 10a, 10b.

  For example, the thermal conductivity of the adhesive 7 is about 0.1 [W / m · K]. Compared to the thermal conductivity of the two-component mixed silicon potting material, it is about 1/3. Therefore, in order to efficiently transmit the heat generated by the bypass diode 4 to the solar cell module 8, the use of the adhesive 7 is minimized. The adhesive 7 is applied so as not to protrude into the heat radiation holes 10a, 10b and the wiring holes 6a, 6b, 6c. The heat radiation holes 10a and 10b and the wiring holes 6a, 6b and 6c are main heat radiation paths for heat generated by the bypass diode 4.

  That is, the adhesive 7 is not applied in the vicinity of the heat radiation holes 10a, 10b and the wiring holes 6a, 6b, 6c. A filler 11 is applied in the vicinity of the heat radiation holes 10a, 10b and the wiring holes 6a, 6b, 6c. Thereby, the heat generated by the bypass diode 4 can be efficiently transmitted to the solar cell module 8.

  FIG. 5 shows an example in which the adhesive is applied in an 8-shaped form. However, as long as the following two requirements are satisfied, the shape is not limited to this. The first requirement is that the filler 11 does not leak from the gap between the housing 1 and the solar cell module 8. The second requirement is that sufficient adhesive strength can be obtained.

  FIG. 6 is a configuration diagram showing a cross-sectional configuration of the terminal box 100. After the terminal box 100 is attached to the solar cell module 8, the circuit component 20 is filled with the filler 11. The filler 11 is filled up to the position of the upper surface 11a of the filler. Specifically, the upper surface 11a of the filler is closer to the lid 9 than the component that protrudes most toward the lid 9 among the components constituting the circuit. All components in the circuit configuration unit 20 are surrounded by the filler 11.

  The temperature of the bypass diode 4 is determined by the amount of heat generated by the bypass diode 4, the outside air temperature, the wind speed, the thermal resistance between the bypass diode and the outside air, and the like. There are two methods for reducing the thermal resistance between the bypass diode 4 and the outside air. The first method is a method of increasing the surface area of the terminal box 100. The second method is a method of reducing the thermal resistance of the heat radiation path from the bypass diode 4 to the outside air. However, the first method for increasing the surface area of the terminal box is not preferable in terms of cost.

  The heat dissipation path of the bypass diode 4 is mainly the following two paths. The first path is a heat dissipation path that is released from the surface of the terminal box 100 to the outside air. A 2nd path | route is a thermal radiation path | route discharged | emitted from the solar cell module 8 to external air, after being transmitted to the solar cell module 8 by heat conduction.

  The side part of the terminal box 100 often employs double walls from the viewpoint of flame retardancy. In this case, there is an air layer between the two walls. Further, the lid 9 is attached to the housing 1 after the filler 11 is cured. For this reason, an air layer also exists between the upper surface 11 a of the filler and the lid 9. This air layer is about several mm.

  The housing 1 and the lid 9 are made of a material such as ABS resin or modified synthetic PPO resin. For this reason, the housing | casing 1 and the lid | cover 9 are excellent in terms of a weather resistance or a flame retardance. However, the thermal conductivity of the housing 1 and the thermal conductivity of the lid 9 are not high. Furthermore, the thermal conductivity of air is an order of magnitude smaller than that of the resin material. That is, the heat dissipation path that is released from the bypass diode 4 to the outside air through the surface of the terminal box 100 has a very large thermal resistance. The contribution ratio to the heat radiation of the first path is small.

  A heat radiation hole 10 is opened on the bottom surface of the housing 1, and a filler 11 is filled between the terminal plate 2 and the solar cell module 8. Thereby, the contact thermal resistance between the terminal board 2 and the solar cell module 8 can be lowered. Further, since the first route using the first method is not selected, the terminal box 100 can be downsized.

  For example, even if the gap between the terminal plate 2 and the housing 1 is only about 1 mm, if the hole 12 of the terminal plate 2 is opened at a position corresponding to the heat radiating hole 10, the filler 11 can be used as the heat radiating hole 10. This part also extends sufficiently to the peripheral part of the heat radiation hole 10. And heat dissipation is not reduced.

  In addition, although the terminal board 2 was demonstrated here as three sheets, the number of the terminal boards 2 is not restricted to three sheets. Moreover, although the bypass diode 4 is described as two, it is not limited to two. Radiation holes 10 are provided according to the number of bypass diodes 4. Furthermore, a hole 12 is provided at the position of the terminal board corresponding to the heat radiating hole 10. Thus, the heat generated by the bypass diode 4 can be efficiently transmitted to the solar cell module 8 and radiated to the outside. As a result, the ambient temperature when the bypass diode 4 operates can be lowered.

  Since the present invention is configured as described above, the heat generated by the bypass diode 4 can be efficiently transmitted to the solar cell module 8. Further, even when the housing 1 and the lid 9 of the terminal box 100 have high thermal conductivity, the heat generated by the bypass diode 4 can be efficiently transmitted to the solar cell module 8.

  DESCRIPTION OF SYMBOLS 1 Case, 10, 10a, 10b Heat radiation hole, 11 Filler, 11a Upper surface of filler, 12 Hole, 13 Potential difference generation area, 14 Opening part, 2, 2a, 2b, 2c Terminal board, 3, 3a, 3b, 3c lead frame, 4, 4a, 4b bypass diode, 41a, 42a, 41b, 42b terminal, 43a, 43b package part, 5 output cable, 6, 6a, 6b, 6c wiring hole, 7 adhesive, 8 solar cell module, 9 lid, 20 circuit components, 100 terminal box.

Claims (4)

A terminal box attached to the solar cell module as an output part of the solar cell module,
A plurality of terminal boards;
A bypass diode connecting between the terminal plates;
A housing that houses a circuit component having the terminal plate and the bypass diode,
The circuit component is filled with a filler having a higher thermal conductivity than the housing,
The mounting surface of the housing is provided with a heat dissipation hole in a region facing the bypass diode,
A terminal box in which the filler is filled between the bypass diode and the solar cell module.   The terminal box according to claim 1, wherein the terminal plate has a hole for injecting a filler on a surface facing the heat radiating hole.   The terminal box according to claim 1, wherein the heat radiating hole does not include a region facing a region having a different potential between adjacent terminal plates. The housing has a region for applying an adhesive for fixing to the solar cell module,
The terminal box according to any one of claims 1 to 4, wherein a region to which the adhesive is applied does not include the heat dissipation hole.

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