JP2015012129A - Joint box of photovoltaic power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joint box capable of disconnecting individual solar cell strings completely from other solar cell strings, in a photovoltaic power generation system of negative ground specification.SOLUTION: The joint box for photovoltaic power generation system includes a plurality of branch switches for switching each solar cell string. Each branch switch 15 includes a positive electrode switch for switching the positive electrode of a solar cell string by connecting a plurality of poles in series, and a negative electrode switch for switching the negative electrode of a solar cell string by a single pole. A housing that includes the negative electrode switch, and a housing that houses only the positive electrode switch are individual housings separable from each other, and the branch switch is constituted by arranging them adjacently.

Description

  The present invention relates to a solar power generation system connection box used in a portion of a solar power generation system where a solar cell string is connected to a power conditioner.

  In a solar power generation system, a plurality of solar cell modules are connected to form a solar cell string and connected to the system. FIG. 1 is a diagram showing an outline thereof. 1 is a solar cell string in which a plurality of solar cell modules are connected, 2 is a connection box, 3 is a DC current collection box, 4 is a power conditioner, 5 is a built-in transformer, etc. The boosting equipment 6 is a system. As shown in Patent Document 1, a branch switch 7 is provided in the inside of the connection box 2 so that the circuit can be turned on and off for each solar cell string in inspection and other cases.

  Such a solar power generation system includes a negative grounding specification for grounding a negative-side electric circuit and a non-grounding specification for not grounding a negative-side electric circuit. As shown in FIG. 1, the grounding is usually performed by the power conditioner 4.

  In the negative electrode grounding specification, a bypass circuit is formed due to a ground fault on the negative electrode side of the solar cell string 1, and the positive circuit may be a high voltage of about 750 to 1000 V, for example. For this reason, it is difficult to open and close the positive electrode circuit with a single contact, and the positive electrode circuit is simultaneously opened and closed with a plurality of contacts. In this case, as shown in FIG. 2, using a two-pole branch switch, the positive circuit can be folded back and opened at the same time with two contacts, and the negative circuit does not pass through the switch. A structure connected to a common negative electrode bar is common.

  However, in such a conventional structure, since each solar cell string is connected to a common negative electrode bar, even if the branch switch is operated, the negative electrode side of the solar cell string is electrically connected from the negative electrode side of another solar cell string. Can not be separated. Therefore, it is difficult to perform an insulation resistance test of the solar cell string during periodic inspections. Further, when repairing a solar cell string in which an accident occurred, there was a problem that it was necessary to make a complete power failure including a healthy solar cell string.

JP 2013-48180 A

  Therefore, the object of the present invention is to solve the above-mentioned conventional problems, and in a photovoltaic power generation system with a negative electrode grounding specification, a connection for a photovoltaic power generation system that can completely separate individual solar cell strings from other solar cell strings. Is to provide a box.

  The present invention made to solve the above problems is a connection box for a photovoltaic power generation system, and includes a plurality of branch switches that open and close the electric path of each solar cell string, and each branch switch includes a plurality of branch switches. A positive electrode opening / closing part that opens and closes the positive electrode of the solar cell string by connecting the poles in series, and a negative electrode opening / closing part that opens and closes the negative electrode of the solar cell string. Each of the separated casings is separable, and these are arranged adjacent to each other to form a branch switch.

  As in claim 2, the positive electrode switching part can be a switch having two or more poles. Further, as in claim 3, the negative electrode switching part can be a single pole switch, or as in claim 4, the negative electrode switching part is a two or more pole switch, and the negative electrode is connected to one of the poles. In addition, a positive electrode circuit can be connected to the other electrode. Further, according to the fifth aspect of the present invention, a switch having two or more poles can be provided with the adjacent terminal portions being different. Further, as in claim 6, the positive electrode opening / closing part can be formed by combining a plurality of single electrode switches.

  As in claim 7, the switch having two or more poles has a structure in which adjacent terminal portions are provided in steps, and a groove portion is provided for securing an insulating distance in a base portion of a partition wall between adjacent terminal portions. can do. Furthermore, it is preferable that the positive electrode opening / closing part and the negative electrode opening / closing part are operated by a common operation part as in claim 8.

  The branch switch of the junction box for a photovoltaic power generation system of the present invention includes a positive electrode switching unit that connects a plurality of poles in series to open and close the positive electrode of the solar cell string. Even when the voltage is about ˜1000 V, the positive electrode circuit can be simultaneously opened and closed by a plurality of contacts. Moreover, since the negative electrode opening / closing part which opens and closes the negative electrode of the solar cell string is provided, the solar cell string can be completely separated from the other solar cell strings by turning off both the positive electrode and the negative electrode.

  In addition, since the casing including the negative electrode opening / closing portion and the casing containing only the positive electrode opening / closing portion are separated from each other and are arranged adjacent to each other to form a branch switch, an existing switch The connection box for a photovoltaic power generation system can be configured using

It is a circuit block diagram which shows the outline | summary of a solar energy power generation system. It is explanatory drawing of a prior art. It is explanatory drawing of the connection box for photovoltaic power generation systems. It is a connection diagram to the switch in 1st Embodiment. It is a connection diagram which shows a modification. It is a connection diagram in the second embodiment. It is a connection diagram in a 3rd embodiment. It is a perspective view of a 2 pole switch. It is a perspective view which shows the state which arrange | positioned the switch of 2 poles adjacently.

Preferred embodiments of the present invention are shown below.
FIG. 3 is an explanatory diagram of a junction box for a solar power generation system, 10 is a DC circuit breaker having an overcurrent cutoff function, 11 is a positive bar, 12 is a negative bar, 13 is a backflow prevention diode, 14 is a lightning protection element, Reference numeral 15 denotes a plurality of branch switches that open and close each solar cell string. A solar cell string is formed by combining a plurality of solar cell modules, and is input to the junction box in units of solar cell strings.

  The branch switch 15 is used for separating the solar cell string from other solar cell strings at the time of maintenance and inspection. The positive electrode that has passed through the branch switch 15 is connected to the positive electrode bar 11 via a backflow prevention diode and further connected to the DC circuit breaker 10. The negative electrode passes through the branch switch 15, is connected to the negative electrode bar 12, and is further connected to the DC circuit breaker 10. The DC breaker 10 collectively outputs the outputs from the solar cell strings to the power conditioner. The backflow prevention diode 13 prevents a current from flowing from a high voltage solar cell string to another solar cell string when a voltage difference occurs between the solar cell strings due to an accident or failure. As described above, the negative electrode is grounded inside the power conditioner.

  In this embodiment, as shown in FIG. 4, a switch having two two-pole switches 21 and 22 arranged as a branch switch 15 is used to open and close the positive and negative electrodes of one solar cell string. ing. The negative electrode of the solar cell string is connected to the left input terminal 23 of one switch 21, drawn from the left output terminal 24, and connected to the negative electrode bar 12. The positive terminal of the solar cell string is connected to the input terminal 25 on the right side of the switch 21. The right output terminal 26 of the switch 21 is connected to the left output terminal 27 of another adjacent switch 22 by a conductor 28, and the left input terminal 29 of the switch 22 is connected by a right input terminal 30 and a conductor 31. It is connected. Then, it is pulled out from the right output terminal 32 and connected to the positive electrode bar 11.

  Thus, the negative switch part (left pole) and the positive switch part (right pole) are housed inside the casing of the switch 21, and two positive switch terminals are placed inside the casing of the switch 22. The part is stored. With this structure, even if a fault such as a ground fault occurs on the negative electrode side of the solar cell string and the positive electrode side becomes a high voltage of about 750 to 1000 V, for example, at the moment of the opening operation, the positive electrode switching unit is only the switch 22. In addition, since the pole on the right side of the switch 21 is also used as the positive electrode switching part, the voltage applied to the positive electrode side can be dispersed. These housings are arranged adjacent to each other as shown in FIG. 4 and can be opened and closed simultaneously by connecting the handles with a handle lever 33 which is a common operation unit. The housing including the negative electrode opening / closing portion and the housing containing only the positive electrode opening / closing portion can be separated, and these are arranged adjacent to each other to constitute a branch switch.

  In the embodiment configured as described above, by operating the handle lever 33, the negative electrode is opened and closed by a single pole of the switch 21, and the positive electrode is simultaneously opened and closed by a total of three poles of the switch 21 and the switch 22. Is done. For this reason, even if the electric circuit of a positive electrode becomes a high voltage, it can be opened and closed by a some contact without trouble. Further, since the negative electrode opening / closing section is provided, the solar cell string can be completely separated from the other solar cell strings by turning off both the positive electrode and the negative electrode.

  The connection method to the branch switch 15 is not limited to the embodiment shown in FIG. 4, and the negative electrode of the solar cell string is connected to the input terminal 23 on the left side of the two-pole switch 21 as shown in FIG. The positive electrode of the solar cell string can also be connected to the input terminal 30 on the right side of the switch 22. In this case, the positive electrode is connected in the order of the input terminal 30, the output terminal 32, the output terminal 27, the input terminal 29, the input terminal 25, and the output terminal 26. In any case, it is preferable that wiring is performed so that the direction of the current is reversed in the casing of the same switch 22.

  In the second embodiment shown in FIG. 6, three single-pole switches 40 are arranged in parallel, one of which is used for the negative electrode and the other two are used for the positive electrode. In this case, the positive electrode is opened and closed by two contact points.

  In the third embodiment shown in FIG. 7, one single-pole switch 40 and two-pole switch 41 are arranged in parallel so that the positive electrode can be opened and closed by two contacts.

  As described above, the negative electrode switching part is a switch of two or more poles, the negative electrode is connected to one pole and the positive circuit is connected to the other pole, or only a single pole switch is used in combination. can do.

  FIG. 8 is a perspective view of the two-pole switch 21 used in the above embodiment. As shown in the figure, the input terminal 23 and the adjacent input terminal 25 are formed in a step difference, and the upper input terminal 25 is extended so as to cover the lower input terminal 23. With such a configuration, the lateral width of the switch 21 can be reduced.

  However, on the other hand, since the distance between the input terminal 23 and the adjacent input terminal 25 is close, dielectric breakdown may occur when a high voltage is applied. Therefore, in FIG. 8, the switch 21 has an L-shaped groove portion 42 formed in the base portion 43 of the central partition wall 44 between these terminals to increase the creeping insulation distance. This structure is the same for the output terminals 24 and 26.

  FIG. 9 is a perspective view showing a state in which two-pole switches 21 and 22 are arranged adjacent to each other. By connecting the handles of the switches 21 and 22 with the handle lever 33 in this way, a plurality of switches can be opened and closed simultaneously.

  As described above, by using the solar power generation system connection box of the present invention, individual solar cell strings can be completely separated from other solar cell strings in a negative electrode grounded solar power generation system. The connection box for a photovoltaic power generation system of the present invention can also be used as a connection box for non-grounding specifications. However, in that case, the number of connectable solar cell strings is halved, but the manufacturer does not need to have two types of inventory.

DESCRIPTION OF SYMBOLS 1 Solar cell panel 2 Connection box 3 DC current collection box 4 Power conditioner 5 Booster equipment 6 System 10 DC circuit breaker 11 Positive electrode bar 12 Negative electrode bar 13 Backflow prevention diode 14 Lightning protection element 15 Branch switch 21 Bipolar switch 22 Two-pole switch 23 Input terminal 24 Output terminal 25 Input terminal 26 Output terminal 27 Output terminal 28 Conductor 29 Input terminal 30 Input terminal 31 Conductor 32 Output terminal 33 Handle lever 40 Single-pole switch 41 Two-pole switch 42 L Shaped groove part 43 Base part 44 Bulkhead

Claims (8)

A junction box for a photovoltaic power generation system, comprising a plurality of branch switches for opening and closing the electric path of each solar cell string,
Each branch switch includes a positive electrode switching unit that opens and closes the positive electrode of the solar cell string by connecting a plurality of poles in series, and a negative electrode switching unit that opens and closes the negative electrode of the solar cell string,
A photovoltaic power generation system characterized in that a casing including a negative electrode opening / closing part and a casing containing only the positive electrode opening / closing part are separated from each other, and are arranged adjacent to each other to form a branch switch. Connection box.   The junction box for a photovoltaic power generation system according to claim 1, wherein the positive electrode switching part is a switch having two or more poles.   The connection box for a photovoltaic power generation system according to claim 1, wherein the negative electrode switching part is a single pole switch.   The connection box for a photovoltaic power generation system according to claim 1 or 2, wherein the negative electrode switching part is a switch having two or more poles, the negative electrode is connected to one pole, and the positive circuit is connected to the other pole. .   The junction box for a photovoltaic power generation system according to claim 2 or 4, wherein the switch having two or more poles is provided with adjacent terminal portions at different levels.   4. The junction box for a photovoltaic power generation system according to claim 3, wherein the positive electrode switching part is formed by combining a plurality of single-pole switches.   The switch having two or more poles is characterized in that adjacent terminal portions are provided in steps, and a groove portion for securing an insulation distance is provided in a base portion of a partition wall between adjacent terminal portions. 4. Connection box for solar power generation system according to 4.   The connection box for a photovoltaic power generation system according to claim 1, wherein the positive electrode opening / closing part and the negative electrode opening / closing part are operated by a common operation part.

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