Solar power generation junction boxes and solar power generation equipment

Abstract

To provide a junction box and solar power generation equipment with improved productivity. [Solution] The present invention is a connection box for solar power generation, comprising an iron housing and an aluminum heat sink provided inside the housing, wherein the housing and the heat sink are joined by plastic deformation of the housing and the heat sink through crimping, and the heat sink has a plurality of protrusions that are convex toward the inside of the housing and have a flat surface with screw holes, and at least one of the plurality of protrusions is a grounding terminal.

Description

TECHNICAL FIELD

[0001] The present invention relates to a junction box for photovoltaic power generation and a photovoltaic power generation apparatus.

BACKGROUND ART

[0002] In a photovoltaic power generation apparatus, a junction box for photovoltaic power generation that connects a solar cell module and a power conditioner is provided. The junction box for photovoltaic power generation is provided with a switch that disconnects the solar cell module from the circuit during maintenance and inspection of the solar cell module, a diode that prevents reverse flow of current, a terminal block, and the like. These components are usually arranged on a heat dissipation plate, particularly to suppress performance degradation due to heat generation from diodes and the like. The heat dissipation plate on which the diodes, switches, terminal blocks and the like are arranged is attached to the inner surface of a metal housing by screws, pop rivets or the like, and is configured to dissipate heat from the housing (see Patent Document 1).

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0003]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] In the conventional junction box for photovoltaic power generation, the heat dissipation plate is attached by screws, pop rivets or the like, which makes the processing steps complicated. In addition, since the junction box for photovoltaic power generation is usually further provided with a ground terminal, a step of attaching a pop nut or the like to serve as the ground terminal is also required. For these reasons, the junction box for photovoltaic power generation is desired to be improved to a structure that can be produced efficiently.

[0005] An object of the present invention is to provide a junction box for photovoltaic power generation and a photovoltaic power generation apparatus with improved productivity.

MEANS FOR SOLVING THE PROBLEMS

[0006] The embodiments of the present invention made to solve the above problems are as follows. [1] A junction box for solar power generation, comprising an iron casing and an aluminum heat sink provided inside the casing, wherein the casing and the heat sink are joined by plastic deformation of the casing and the heat sink by crimping, and the heat sink has a plurality of protrusions that are convex toward the inside of the casing and have a flat surface with screw holes, and at least one of the plurality of protrusions is a grounding terminal. [2] The photovoltaic connection box according to [1], wherein at least one switch and terminal block are arranged on at least one of the multiple protrusions other than the grounding terminal. [3] A solar power generation junction box according to [1] or [2], wherein the thickness of the iron plate material constituting the enclosure is 0.3 mm or more and 1.5 mm or less, and the thickness of the heat sink is 2 mm or more and 5 mm or less. A solar power generation device equipped with a solar power generation junction box as described in any of [4][1] to [3]. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a junction box for solar power generation and solar power generation equipment with improved productivity. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic plan view showing the housing and heat sink of a junction box for solar power generation according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic plan view showing a solar power generation junction box with the lid removed, according to one embodiment of the present invention. [Figure 3] Figure 3 is a circuit diagram of a junction box for solar power generation according to one embodiment of the present invention. [Figure 4] Figure 4 is a schematic cross-sectional view showing the crimped portion between the housing and the heat sink. [Figure 5] Figure 5 is an AA line end view of the housing and heat sink shown in Figure 1. [Figure 6]Figure 6 is an end view of the BB line portion of the housing and heat sink shown in Figure 1. [Figure 7] Figure 7 is a schematic plan view showing a heat sink of a different form than the heat sink in Figure 1. [Figure 8] Figure 8 is an end view of the CC line portion of the heat sink shown in Figure 7. [Modes for carrying out the invention]

[0009] The following describes in detail a junction box for solar power generation and solar power generation equipment according to one embodiment of the present invention, with reference to the drawings as appropriate.

[0010] The solar power generation junction box 1 shown in Figure 1 comprises an iron casing 2 and an aluminum heat sink 3 installed inside the casing 2. The solar power generation junction box 1 in Figure 1 shows the casing 2 without its lid (top cover), and without the switches, diodes, terminal blocks, and their wiring that are placed on the heat sink 3. In other words, the solar power generation junction box 1 in Figure 1 shows only the casing 2 and the heat sink 3. The heat sink 3 may be installed on the inner surface of the casing 2. In this embodiment, the heat sink 3 is installed on the bottom surface, which is one of the inner surfaces of the casing 2. Note that in Figure 1 and Figure 2, which will be described later, the solar power generation junction box 1 is shown as a plan view with the bottom surface of the casing 2 facing downwards. However, when actually used, the solar power generation junction box 1 is installed with the bottom surface of the casing 2 parallel to the wall of a house or the like (perpendicular to the ground).

[0011] In actual use, as shown in Figure 2, switches 4 (4a-4c), diodes 5 (5a-5c), and terminal block 6 are arranged on the heat sink 3 of the solar power generation junction box 1. Other components may also be arranged on the heat sink 3. The housing 2 is used with the lid attached. Switches 4 (DC switches) open and close the current path between the solar cell modules and the power conditioner. Diodes 5 (reverse current prevention diodes) prevent reverse current flow. Terminal block 6 collects the current generated by each solar cell module and outputs it to the power conditioner. Heat sink 3 dissipates the heat generated by diodes 5, etc. Housing 2 is a box that houses these components. The iron housing 2, which is joined to the heat sink 3, also contributes to heat dissipation. Note that the arrangement of switches 4, diodes 5, and terminal block 6 shown in Figure 2 is an example and is not limited to this. Furthermore, although each of the photovoltaic power generation junction boxes 1 shown in Figure 2 has three switches 4 and three diodes 5, this corresponds to the number of solar cell modules, and the number of switches 4 and diodes 5 is not limited. Although the wiring is not shown, it is wired in the same way as conventional photovoltaic power generation junction boxes, so that the power generated by the solar cell modules is output in the order of switches 4, diodes 5, terminal block 6, and power conditioner.

[0012] First, the operation of the solar power generation junction box 1 will be explained with reference to Figure 3. The wiring diagram in Figure 3 shows a wiring diagram in which three rows of solar cell modules are connected. The outputs of the three solar cell modules 7a to 7c are combined into a single output and connected to terminal block 6 after passing through switches 4a to 4c and diodes 5a to 5c. Each switch 4 is for connecting and disconnecting the output of each solar cell module 7. The DC output of the solar cell modules, combined into a single output at terminal block 6, is sent to the power conditioner 8, where it is converted into AC power. The positive (+) output terminal and the negative (-) output terminal of each switch 4 are connected by surge absorbers such as varistors to protect each solar cell module 7 from surge voltages such as lightning. The solar power generation junction box 1 is also provided with a grounding terminal 13, to which an earth wire is connected for grounding.

[0013] Each diode 5 is provided for protection in case of incorrect wiring by the contractor. For example, if the positive and negative sides of the solar cell module are connected in reverse, a reverse voltage may be applied to the input of the power conditioner, potentially damaging the power conditioner. Each diode 5 prevents the application of such a reverse voltage. It also prevents current from flowing back from the power conditioner to the solar cell module when the output of the solar cell module decreases. Furthermore, if the output of one of the multiple strings decreases for any reason, it prevents current from flowing back from the high-output string to the low-output string. Normally, forward current from the solar cell module flows through each diode 5. The loss (power consumption) in each diode 5 is large, generating considerable heat. Therefore, each diode 5 is placed on a heat sink 3 to allow for heat dissipation.

[0014] The following describes in detail the features of the photovoltaic power generation junction box 1 according to one embodiment of the present invention.

[0015] The housing 2 is a substantially rectangular parallelepiped or substantially cubic iron box, and is preferably formed of a plated steel sheet from the viewpoint of corrosion resistance and the like. In particular, a plated steel sheet having a plated layer containing at least one selected from the group consisting of zinc, aluminum and magnesium is preferred. The housing 2 is usually provided with an openable and closable lid. By using an iron housing as the housing 2, it is possible to secure sufficient heat dissipation while suppressing production costs, for example, as compared with the case where an aluminum housing is used.

[0016] The thickness of the iron plate material constituting the housing 2 is preferably 0.3 mm or more and 1.5 mm or less, and more preferably 0.5 mm or more and 1.0 mm or less. When the thickness of the plate material constituting the housing 2 is within the above range, strength, heat dissipation, weight reduction and the like can be optimized in a well-balanced manner.

[0017] The heat dissipation plate 3 is a substantially square plate material made of aluminum in a front view. The heat dissipation plate 3 is arranged inside the housing 2 such that one surface thereof is in contact with the inner surface of the housing 2 (in the present embodiment, the bottom surface which is the inner bottom surface of the housing 2). By using an aluminum heat dissipation plate as the heat dissipation plate 3, good heat dissipation performance can be exhibited.

[0018] The thickness of the heat dissipation plate 3 is set in consideration of the balance of the amount of heat to be dissipated, weight, cost, and the like. For example, from the viewpoint of weight reduction and cost reduction, a thinner heat dissipation plate is desirable, but if it is too thin, the function as a heat dissipation plate may deteriorate. The thickness of the heat dissipation plate 3 is preferably 2 mm or more and 5 mm or less, and more preferably 2.5 mm or more and 4 mm or less. When the thickness of the heat dissipation plate 3 is within the above range, heat dissipation, weight reduction, cost reduction and the like can be optimized in a well-balanced manner.

[0019] The housing 2 and the heat dissipation plate 3 are joined by plastic deformation of the housing 2 and the heat dissipation plate 3 by caulking. That is, the housing 2 and the heat dissipation plate 3 are joined only by plastic deformation of the housing 2 and the heat dissipation plate 3, without using, for example, screws, pop rivets or the like, and without relying on welding. For this reason, the connection box 1 for photovoltaic power generation has a reduced number of components, and the processing steps can also be shortened.

[0020] The crimping of the housing 2 and the heat sink 3 can be performed, for example, at the four corners or near the corners of the heat sink 3, which is rectangular in plan view. Figures 1 and 2 show four crimping points 9, but the position and number of crimping points 9 are not limited to these. The crimping of the housing 2 and the heat sink 3 can be performed, for example, as follows: First, a hole 14 is made in the housing 2, and the housing 2 and the heat sink 3 are placed on top of each other. As a specific example, a hole 14 is made in the bottom surface of the housing 2, and the heat sink 3 is placed on the bottom surface of the housing 2. In this state, the heat sink 3 located in the hole of the housing 2 is pressed against the hole of the housing 2 using a jig or the like. As a result, as shown in Figure 4, the heat sink 3 is plastically deformed and inserted into the hole 14 of the housing 2, and the housing 2 and the heat sink 3 can be joined together. Alternatively, a projection may be made on one of the housing 2 and the heat sink 3, and a hole may be made on the other, the projection may be inserted into the hole, and the crimping may be performed by crushing the tip of the projection protruding from the hole. In addition, known crimping technologies such as TOX® crimping joint from Toxpresso Technique, Crimping King® and Crimping Queen® from Sanyo Kiko, and Drawlock crimping from Enami Seiki can also be employed. The crimped portion 9 may have a recessed shape on the heat sink 3 side. Conversely, the crimped portion 9 may have a recessed shape on the housing 2 side. At least one of the housing 2 side and the heat sink 3 side of the crimped portion 9 may be substantially flat or may protrude.

[0021] The heat sink 3 has a plurality of protrusions 10 (10a to 10h). The plurality of protrusions 10 may be embossed. The protrusions may also be called embossed parts, stepped parts, island-shaped parts, etc. Each protrusion 10 has a shape that is convex toward the inside of the housing 2. In other words, each protrusion 10 is convex toward the opposite side of the inner surface (bottom surface in this embodiment) of the housing 2. That is, each protrusion 10 is concave on the side facing the inner surface of the housing 2 and protrudes toward the opposite side on which the switch 4, etc., is placed. One side of each protrusion 10 is convex, and the other side is concave, following the shape of the other side. Also, as shown in Figures 5 and 6, each protrusion 10 has a flat surface 12 on which screw holes 11 are provided. That is, as shown in Figures 5 and 6, each protrusion 10 has a substantially trapezoidal shape in cross-sectional view. The height H of each protrusion 10 (see Figure 5) may be, for example, 2 mm or more and 5 mm or less, or 2.5 mm or more and 4 mm or less.

[0022] The heat sink 3 can be formed, for example, by pressing an aluminum plate. In the heat sink 3, the thickness of the protrusions 10 and the thickness of the parts other than the protrusions 10 may be substantially the same.

[0023] Of the multiple (eight in Figure 1) protrusions 10 shown in Figure 1, the protrusion 10h located in the lower right is used as a grounding terminal. The protrusion 10h differs in shape from the other protrusions 10a to 10g, having a substantially elliptical shape in plan view and having two screw holes 11. Of the two screw holes 11 provided in the protrusion 10h, one screw hole 11 is used for connecting the ground wire from the solar cell module, and the other screw hole 11 is used for connecting the ground wire to a reference potential point (generally earth). In another embodiment, a protrusion with only one screw hole provided as the grounding terminal may be used.

[0024] Furthermore, among the multiple protrusions 10 shown in Figure 1, switches and terminal blocks can be placed on protrusions 10a to 10g other than the grounding terminal protrusion 10h described above. Protrusions 10a to 10g have a circular shape in plan view. As shown in Figure 2, in the photovoltaic power generation junction box 1 of this embodiment, the first switch 4a is placed on protrusions 10a and 10b, the second switch 4b is placed on protrusions 10c and 10d, the third switch 4c is placed on protrusions 10e and 10f, and the terminal block 6 is placed on protrusion 10g.

[0025] In the solar power generation junction box 1, a protrusion 10h is used as the grounding terminal. The ground wire can be connected, for example, by inserting a screw member through the crimp terminal of the ground wire and screwing it into the screw hole 11. As mentioned above, considering cost, weight, etc., it is preferable for the heat sink 3 to be as thin as possible, but if the heat sink 3 is thin, it becomes difficult to securely fasten it with screws. In contrast, in the solar power generation junction box 1, a protrusion 10h that is convex toward the inside of the housing 2 and has a screw hole 11 is used as the grounding terminal, and a space is formed between the protrusion 10h and the inner surface of the housing 2. Therefore, even if the heat sink 3 is thin, this stepped structure ensures sufficient depth for screwing in the screw member, enabling secure screw fastening.

[0026] Furthermore, in the solar power generation junction box 1, the switch 4 and terminal block 6 are arranged on the protrusion 10, and these can also be fixed by inserting screw members through the screw insertion holes provided in the switch 4 and terminal block 6 and screwing them into the screw holes 11. In this case as well, the screw holes 11 are provided in the protrusion 10 which protrudes toward the inside of the housing 2, and a space is formed between the protrusion 10 and the inner surface of the housing 2. Therefore, even if the heat sink 3 is thin, sufficient depth is secured for screw members to be screwed in, enabling stable screw fastening, and thus stable mounting of the switch 4 and terminal block 6.

[0027] Each diode 5 may be fixed to the heat sink 3 by screwing it into a screw hole (not shown), or it may be fixed by other means. Here, the electrical circuit including the diodes 5 and the protrusion 10h which is the grounding terminal must be electrically insulated. For this reason, an insulating sheet (not shown) is usually placed between the heat sink 3 and the diodes 5. Furthermore, an insulating sheet may also be placed between the heat sink 3 and the switch 4 or terminal block 6. There may be only one insulating sheet or multiple sheets. The insulating sheets should be placed so that the electrical circuit including the diodes 5 and the protrusion 10h which is the grounding terminal is electrically insulated. On the other hand, the protrusion 10h which is the grounding terminal and the housing 2 are electrically conductive, for example, because the heat sink 3 with the protrusion 10h and the housing 2 are joined by crimping.

[0028] In other embodiments, some of the multiple protrusions 10 may not have switches, terminal blocks, etc., on them. For example, the photovoltaic connection box 1 shown in Figure 1 can also be used to connect two solar cell modules to a power conditioner, with two switches 4 and two diodes 5 corresponding to them.

[0029] The photovoltaic power generation junction box 1 can be manufactured by combining conventionally known methods. For example, it can be manufactured by the following process: A heat sink 3 is made by embossing, drawing, tapping, etc., on an aluminum sheet metal. A housing 2 is made by pressing, etc., on an iron sheet metal. The housing 2 and the heat sink 3 are joined by crimping. The pressing, etc., to obtain the housing 2 and the joining of the housing 2 and the heat sink 3 by crimping may be performed simultaneously or sequentially. After joining the housing 2 and the heat sink 3, they may be painted or otherwise painted. When painting is performed, it is preferable not to paint the housing 2, etc., before joining the housing 2 and the heat sink 3 in order to ensure electrical conductivity between the housing 2 and the heat sink 3 (the protrusion 10h which is the grounding terminal). In other words, it is preferable that the iron housing 2 and the aluminum heat sink 3 are in direct contact without an insulating material such as paint. Furthermore, the mounting of the switch 4, diode 5, terminal block 6, etc. to the heat sink 3 is as described above and can be done by known methods.

[0030] In this solar power generation junction box 1, the housing 2 and the heat sink 3 are joined by plastic deformation of the housing 2 and the heat sink 3 through crimping, eliminating the need for screws, pop rivets, and other materials for joining. Furthermore, the manufacturing process is shortened by performing the press processing of the housing 2 and the crimping of the housing 2 and the heat sink 3 simultaneously or continuously. In addition, by using one of the protrusions 10h on the heat sink 3 as a grounding terminal, pop nuts and the like for attaching grounding terminals are also unnecessary. The processing to attach protrusion 10h as a grounding terminal can be performed simultaneously with the processing to attach the other protrusions 10a to 10g, thus reducing the manufacturing process by eliminating the need for steps such as attaching pop nuts as grounding terminals. In this way, the productivity of this solar power generation junction box 1 is improved, allowing for efficient manufacturing.

[0031] Furthermore, in the photovoltaic power generation junction box 1, the switch 4 and terminal block 6 are positioned on the protrusions 10a to 10g, excluding the protrusion 10h used as the grounding terminal. As a result, the contact area between the surface of the heat sink 3 and the switch 4 and terminal block 6 is reduced, and the protrusions 10 allow air to flow more easily over the surface of the heat sink 3, thereby improving the heat dissipation performance of the heat sink 3.

[0032] The present invention is not limited to the embodiments described above, and its configuration can be modified without altering the gist of the invention. For example, the shape of the housing, heat sink, etc., is not limited to the shapes described above, and the number and shape of the multiple protrusions provided on the heat sink are also not limited. The number of protrusions may be two or more, for example, four to twenty, or six to fifteen.

[0033] The multiple protrusions may be formed in an island-like (embossed) shape on the heat sink 3 as shown in Figure 1, or they may be formed as steps at the corners of the heat sink. As an example of such a heat sink, the heat sink 31 shown in Figures 7 and 8 has multiple protrusions 10a to 10g and 10i. The multiple protrusions 10a to 10g on the heat sink 31 are the same as the multiple protrusions 10a to 10g on the heat sink 3 shown in Figure 1. The protrusion 10i on the heat sink 31 is formed in a stepped shape at the corner of the heat sink 31 and is approximately rectangular in plan view. Like the other protrusions 10a to 10g, the protrusion 10i is convex toward the inside of the housing 2 and has a flat surface with screw holes 11. A protrusion 10i of this shape can be formed by press working such as drawing or bending. The protrusion 10i may also be called a stepped drawing portion. In the heat sink 31, the protrusion 10i of this shape can be used as a grounding terminal.

[0034] Furthermore, the solar power generation junction box of the present invention may be integrated with other devices such as a power conditioner. In other words, the present invention can also be applied to power conditioners and the like that have the function of a junction box.

[0035] A photovoltaic power generation device according to one embodiment of the present invention includes a photovoltaic power generation junction box according to one embodiment of the present invention. The photovoltaic power generation device is the same as conventionally known photovoltaic power generation devices except that it includes a photovoltaic power generation junction box according to one embodiment of the present invention as a junction box. The photovoltaic power generation device further includes, for example, a solar cell module and a power conditioner, and the solar cell module and the power conditioner are connected by a photovoltaic power generation junction box. [Industrial applicability]

[0036] The solar cell junction box and photovoltaic power generation equipment of the present invention can be widely used in photovoltaic power generation equipment for homes, factories, and the like. [Explanation of Symbols]

[0037] 1. Solar cell junction box 2 cabinets 3, 31 Heat sink 4(4a~4c) Switch 5 (5a~5c) diode 6 Terminal block 7 (7a~7c) Solar cell modules 8 Power Conditioner 9. Crimping area 10 (10a~10i) Convex part 11 screw holes 12 flat surface 13 Ground terminal 14 holes

Claims

1. Iron casing, An aluminum heat sink provided inside the above enclosure and Equipped with, The above-mentioned housing and the above-mentioned heat sink are joined by plastic deformation of the housing and the heat sink through crimping. The heat sink described above comprises a plurality of protrusions that are convex toward the inside of the housing and have a flat surface with screw holes, A junction box for solar power generation, wherein at least one of the multiple protrusions described above is a grounding terminal.

2. The photovoltaic connection box according to claim 1, wherein at least one switch and terminal block are arranged on at least one of the multiple protrusions other than the grounding terminal.

3. The thickness of the iron plate material constituting the above enclosure is 0.3 mm or more and 1.5 mm or less. The photovoltaic connection box according to claim 1 or claim 2, wherein the thickness of the heat sink is 2 mm or more and 5 mm or less.

4. A solar power generation device comprising a junction box for solar power generation according to claim 1 or claim 2.

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