JP2015023254A - Joint box for photovoltaic power generation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joint box for photovoltaic power generation which allows for reductio of the number of switches to one for two solar cell strings, without changing a heat dissipation structure significantly.SOLUTION: A heat dissipation plate 4 wide enough to cover the apparatus attachment region entirely is placed tightly on the back plate 5a of a joint box body 5, and a switch 1 and a diode module 2 are installed on the heat dissipation plate 4. Each individual switch 1 is connected in parallel with two solar cell strings, the diode module 2 is bonded to the heat dissipation plate 4, the switch 1 is installed on the heat dissipation plate 4 via a switch mount 11, a heat dissipation space is formed by the switch mount 11, and an opening 11c for housing the diode module 2 is provided in the switch mount 11.

Description

  The present invention relates to a photovoltaic power generation connection box for collecting power generated by individual solar cells in a photovoltaic power generation system including a plurality of solar cell strings.

  In the solar power generation system, power is generated by a plurality of solar battery panels, and the generated DC power is collected into one system output in a connection box and sent to a power conditioner for conversion to AC power. Therefore, the junction box incorporates a switch for disconnecting the solar cell from a circuit such as a power conditioner, a backflow prevention diode for preventing current from flowing into the solar cell, and a surge absorber.

  Since such a junction box is installed outdoors together with the solar cell panel, it is formed so as to be airtight so that rainwater or the like does not enter, but since the built-in backflow prevention diode generates heat, this heat dissipation measure is It was necessary. For example, in Patent Document 1, a part of a heat radiating plate to which a backflow prevention diode is attached is arranged so as to be in close contact with the top plate of the connection box, and a main part is arranged in parallel to face the back of the connection box, Efficient heat dissipation was carried out by sticking a heat dissipation sheet on both sides.

Special table 2013-512263 gazette

As the scale of power generation increases, the number of solar cell panels that collect current, that is, the number of solar cell strings increases, so the number of switches and backflow prevention diodes increase proportionally, and the junction box increases in size. Furthermore, as the number of solar cell panels increases, the installation area itself increases, so the distance to the junction box also increases and the amount of wiring cords used also increases.
And, as the scale of power generation increases, the amount of heat generated by the backflow prevention diode also increases, so a more effective structure for heat dissipation measures is required.
In view of such a situation, it has become necessary to efficiently dissipate heat and downsize the junction box. For example, if one switch is used for two solar cell strings, the number of switches and the number of backflow prevention diodes can be halved compared to the conventional configuration. However, the amount of heat generated per backflow prevention diode doubles on the contrary, and a sufficient heat dissipation measure was still necessary.

  Therefore, in view of such problems, the present invention is a junction box for photovoltaic power generation that can reduce the number of switches to one for two solar cell strings without greatly changing the heat dissipation structure. The purpose is to provide.

In order to solve the above-mentioned problem, the invention of claim 1 is connected to a plurality of switches to which output lines of a solar cell string in which a plurality of solar cell panels are connected in series are connected, and to an output side of the switch. A junction box for photovoltaic power generation in which a backflow prevention diode is housed, wherein a heat sink having a width covering at least a mounting area of the switch is disposed on the inner back plate of the junction box, and the switch And the backflow prevention diode is disposed on the heat sink, and each of the switches is connected to the two solar cell strings connected in parallel, and the backflow prevention diode is fixed to the heat sink. It is characterized by that.
According to this configuration, a heat sink having a width covering at least the switch mounting area of the junction box is arranged, and the heat can be radiated satisfactorily because it is in close contact with the back plate, and the backflow prevention diode can be radiated without forced air cooling or the like. Can be implemented. Therefore, it is possible to correspond to two solar cell strings with one switch and a backflow prevention diode, and the number of switches and the number of backflow prevention diodes are half of the number of solar cell strings. The cost can be reduced and the junction box can be made smaller.
Also, if two solar cell strings connected to the same switch are connected in parallel at the solar cell panel installation location, only one system of wiring is required up to the connection box, so that the amount of wiring used can be reduced.

According to a second aspect of the present invention, in the configuration according to the first aspect, a terminal block for collecting the outputs of the plurality of solar cell strings in one system and sending it to the outside is provided on the heat radiating plate, and the open / close The switch is disposed on the heat sink via a switch mount, and the backflow prevention diode is disposed in the vicinity of the output terminal of the switch, and the switch mount has a heat dissipation space extending vertically. And a conductor for connecting the backflow prevention diode to the terminal block.
According to this configuration, since the heat radiating space and the conductor are provided on the switch mounting base, even if the switch is installed on the heat radiating plate, the heat radiating action does not decrease and wiring is not necessary. Therefore, the device can be assembled in a minimum space, and the connection box can be reduced in size. Further, the switch and the backflow prevention diode can be brought close to each other and can be connected by a short conductor or the like.

According to a third aspect of the present invention, in the configuration of the first or second aspect, mounting pieces for fixing the connection box to a mounting target are provided on the left and right sides, and the mounting pieces are provided on a back plate of the connection box. On the other hand, it has a mounting surface protruding rearward and parallel to the back plate.
According to this configuration, since the attachment piece protrudes rearward from the connection box back plate, even if the attachment object is a flat wall surface, a gap is formed between the attached connection box and the attachment object. Therefore, even if the back plate is heated to a high temperature due to the heat generated by the backflow prevention diode, air convection can be generated in the gap to dissipate heat, and heat can be prevented from being accumulated.

According to a fourth aspect of the present invention, in the configuration according to any one of the first to third aspects, the switch mounting base is provided with a housing portion for the backflow prevention diode, and the housing portion is formed of the backflow prevention diode. At least a part is formed so as to enter the back of the switch, and the input terminal of the backflow prevention diode can be arranged close to the output terminal of the switch.
According to this configuration, since the backflow prevention diode can be disposed so as to be embedded in the switch mounting base that is the back of the switch, the output terminal of the switch and the input terminal of the backflow prevention diode can be smoothly and closely disposed, and the short Both can be connected by wiring. In addition, since at least a part of the backflow prevention diode and the switch are stored in an overlapping manner, it can be stored in a small space and contributes to downsizing of the junction box.

According to the present invention, a heat sink is disposed over the entire device mounting region of the junction box, and since it is closely attached to the back plate, heat can be radiated satisfactorily, and the backflow prevention diode can be radiated without forced air cooling. Therefore, it is possible to correspond to two solar cell strings with one switch and a backflow prevention diode, and the number of switches and the number of backflow prevention diodes are half of the number of solar cell strings. The cost can be reduced and the junction box can be made smaller.
Also, if two solar cell strings connected to the same switch are connected in parallel at the solar cell panel installation location, only one system of wiring is required up to the connection box, so that the amount of wiring used can be reduced.

It is explanatory drawing which shows an example of the connection box for solar power generation concerning this invention, and has shown the front view which removed the cover plate. It is the sectional view on the AA line of FIG. It is an enlarged view of the C section. It is the BB sectional view taken on the line of FIG. It is a schematic diagram which shows the relationship between the junction box of FIG. 1, and a crystalline solar cell string. It is a schematic diagram which shows the relationship between the junction box of FIG. 1, and a thin film type solar cell string. It is a front view of a switch mounting base. It is a bottom view of a switch mounting base. It is DD sectional view taken on the line. It is the figure which showed typically the cross section of the switch mounting base.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an example of a connection box for photovoltaic power generation according to the present invention, and shows a front view of a connection box with a cover plate removed. In FIG. 1, 1 is a switch to which wiring arranged from a solar cell string is connected, 2 is a diode module incorporating a pair of diodes (backflow prevention diodes), and 3 is a system that outputs collected power in one system 4 is a heat sink for radiating heat generated in the diode module 2, 5 is a connection box body, and 6 is an attachment piece for fixing the connection box body 5 to an attachment object such as a wall surface. .
Moreover, the wiring 7 shown in FIG. 1 shows the wiring which connects the output of the diode module 2 which is an output of a solar cell string to the terminal block 3, and omits one system output line etc. sent from the terminal block 3. is there.

  Since the connection between the output terminal of the switch 1 and the diode module 2 is connected by an insert-molded conductor, it does not appear on the surface. Moreover, the wiring from the solar cell string connected to the switch 1 is introduced from an opening provided on the side surface or the bottom surface of the connection box body 5. The diode module 2 is applied with, for example, 500V, 20A specifications.

The heat radiating plate 4 is formed of a flat metal plate having a size over the entire device mounting area in the junction box. Note that the upper and lower sides are bent in a band shape so that they do not deform and can be used as handles when attaching / removing.
And as shown in the AA sectional view of FIG. 2, it is screwed to the back plate 5a of the connection box main body 5 with a bolt 8 and is in close contact with the back plate 5a.

The switch 1 and the terminal block 3 are attached to the heat sink 4 with a space. In particular, the switch 1 is attached to the heat sink 4 via a switch mounting base 11 made of synthetic resin. In the switch mounting base 11, a heat radiating space that promotes heat dissipation is formed between the switch 1 and the heat radiating plate 4, and a conductor for connecting the output terminal of the diode module 2 to the terminal block 3 is insert-molded. , Buried. And the terminal block 3 is attached to the heat sink 4 via the base 12 which bent and formed the steel plate.
FIG. 10 is a diagram schematically showing a cross section of the switch mounting base 11, and shows a state in which the output terminal of the diode module 2 and the output terminal 16 of the switch mounting base 11 are connected by a conductor 18. ing. The output terminals 16 are connected to the outputs of the two diode modules 2, respectively. In addition, 18a has shown the conductor arrangement | positioning part which insert-molded the conductor.

  FIG. 3 is an enlarged view of the C portion, and shows the relationship between the diode module 2 and the heat sink 4. A heat radiating plate 2a is integrally formed on the bottom of the diode module 2 (the surface facing the terminal arrangement surface), and is in close contact with the heat radiating plate 4 for good heat dissipation.

  FIG. 4 shows a cross section taken along line B-B. As shown in FIG. 4, the mounting piece 6 is fixed to the back portion of the back plate 5a of the junction box body 5 so as to protrude sideways. A hole 6a (shown in FIG. 1) for bolting the object is provided. The mounting piece 6 is formed of a flat plate and is disposed so as to protrude slightly rearward from the back plate 5a. However, a leg portion extending rearward may be provided to further protrude rearward.

  5 and 6 are schematic diagrams showing the relationship between the junction box and the solar cell string, and FIG. 5 is a configuration in which the solar cell string 13 formed by the solar cell 13a composed of the crystalline solar cell elements is connected. Is shown. When the solar cell is a crystal system, as shown in FIG. 5, each solar cell string 13 can be connected in parallel by incorporating a backflow prevention diode 14, and two of them are connected in parallel and then introduced into the connection box 10 to be opened and closed. Connected to. Reference numeral 20 denotes a backflow prevention diode incorporated in the diode module 2.

  On the other hand, FIG. 6 shows a configuration in which solar cell strings 15 formed by solar cells 15a composed of thin film solar cell elements are connected. When the solar cell is a thin film system, it can be directly connected in parallel as shown in FIG. 6 and connected in parallel to the switch 1 after being connected in parallel two by two.

  FIG. 7 is a front view of the switch mounting base 11 in which the switch 1 and the diode module 2 are assembled, FIG. 8 is a bottom view thereof, and FIG. 9 is a sectional view taken along the line DD. The switch mounting base 11 has fixing leg portions 11a having screw insertion holes at four corners, and leg portions 11b are provided at predetermined intervals between the fixing leg portions 11a. A heat dissipating space that promotes heat dissipating the installed diode module 2 is formed vertically. The switch mounting base 11 is fixed to the heat radiating plate 4 with screws 17 inserted through the fixing legs 11a.

  Further, the switch mounting base 11 is provided with an opening 11 c for accommodating the diode module 2. As shown in FIG. 9, the opening 11 c is formed on the output terminal side of the switch 1 so that a part of the accommodated diode module 2 is embedded in the back of the switch 1 and the connection terminal is arranged. It is formed so that the upper surface of the module 2 is exposed.

As shown in FIG. 7, the diode module 2 has three terminals (two input terminals 20a and one output terminal 20b) arranged on the upper surface, and is screwed to the heat radiating plate 4 (not shown). .
Reference numeral 1a denotes an input terminal of the switch 1, and an output terminal (not shown) is connected to the diode module 2 through a conductor 18 shown in FIG. 10 provided by insert molding.

In this way, the heat sink 4 is arranged over the entire device mounting area of the junction box 10 and can be radiated well because it is in close contact with the back plate 5a. Heat dissipation can be performed. Therefore, it is possible to correspond to the two solar cell strings 13 (15) with one switch 1 and the backflow prevention diode 20, and the number of the switch 1 to the number of the solar cell strings 13 (15). And the number of backflow prevention diodes 20 can be halved, the cost can be reduced, and the junction box can be made smaller.
Further, if two solar cell strings 13 (15) connected to the same switch 1 are connected in parallel at the solar cell panel installation location, only one system of wiring is required up to the connection box 10, so that the amount of wiring used can be reduced.

Furthermore, since the heat radiating space and the conductor 18 are provided on the switch mounting base 11, even if the switch 1 is installed on the heat radiating plate 4, the heat radiating action does not decrease, and no separate wiring is required. Therefore, a device can be assembled in a minimum space, and the connection box 10 can be reduced in size. Further, the switch 1 and the backflow prevention diode 20 can be brought close to each other and can be connected by a short conductor or the like.
Further, since the attachment piece 6 protrudes rearward from the connection box back plate 5a, even if the attachment object is a flat wall surface, a gap is formed between the attached connection box 10 and the attachment object, thereby preventing backflow. Even if the back plate 5a becomes high temperature due to the heat generated by the diode 20, air convection can be generated in the gap to dissipate heat, and heat can be prevented from being accumulated.
In addition, since the backflow prevention diode 20 can be disposed so as to be embedded in the switch mounting base 11 which is the back of the switch 1, the output terminal of the switch 1 and the input terminal 20a of the backflow prevention diode 20 are smoothly and closely arranged. Can be connected with a short wiring. Further, since at least a part of the backflow prevention diode 20 and the switch 1 are stored in an overlapping manner, they can be stored in a space-saving manner and contribute to the downsizing of the junction box.

In the above embodiment, the diode module 2 having a pair of backflow prevention diodes 20 is used, but a diode that is not modularized may be used as the backflow prevention diode 20. Further, although a part of the diode module 2 is arranged so as to overlap with the switch 1, the entire diode module 2 may be arranged on the back of the switch 1, which can further contribute to downsizing of the junction box 10.
Moreover, although the conductor is arrange | positioned by the insert molding to the switch mounting base 11, you may perform the wiring of the output of the diode module 2 by arrange | positioning an electric wire using heat dissipation space.
Furthermore, although the size of the heat radiating plate 4 is wide enough to cover the entire device mounting area, good heat dissipation is possible to the outside as long as it covers at least the mounting area of the switch 1.

  1 .... Switch, 1a ... Output terminal 2 .... Diode module 3 .... Terminal block 4 .... Heat sink 5 .... Connection box body 10 .... Connection box 11, ... Switch mounting base 11c ... Opening (diode module housing) 13, 15 ... Solar cell string, 18 ... Conductor, 18a ... Conductor arrangement, 20 ... Backflow prevention diode, 20a ... Input terminal.

Claims (4)

A junction box for photovoltaic power generation in which a plurality of switches connected to output lines of a solar cell string in which a plurality of solar cell panels are connected in series, and a backflow prevention diode connected to the output side of the switch are housed. There,
A heat sink having a width that covers at least the mounting area of the switch is closely arranged on the inner back plate of the junction box, and the switch and the backflow prevention diode are arranged on the heat sink,
Each of the switches is connected with two solar cell strings connected in parallel,
The junction box for photovoltaic power generation, wherein the backflow prevention diode is fixed to the heat radiating plate. A terminal block for concentrating the output of the plurality of solar cell strings in one system and sending it to the outside is provided on the heat sink,
The switch is disposed on the heat sink via a switch mount, and the backflow prevention diode is disposed in the vicinity of the output terminal of the switch,
2. The switch mounting base is provided with a heat radiation space extending vertically, and a conductor for connecting the backflow prevention diode to the terminal block is provided. Connection box for photovoltaic power generation. Mounting pieces for fixing the connection box to the mounting object are provided on the left and right sides, and the mounting pieces protrude rearward with respect to the back plate of the connection box and have a mounting surface parallel to the back plate. The junction box for photovoltaic power generation according to claim 1 or 2, wherein The switch mounting base is provided with a receiving portion for the backflow prevention diode,
The accommodating portion is formed such that at least a part of the backflow prevention diode enters the back portion of the switch,
4. The connection box for photovoltaic power generation according to claim 1, wherein an input terminal of the backflow prevention diode can be disposed close to an output terminal of the switch. 5.

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