JP6271306B2 - Solar power system - Google Patents

Description

  The present invention relates to a photovoltaic power generation system.

  In recent years, power generation systems that use natural energy, such as solar power generation systems that use solar energy, have attracted attention. Such a solar power generation system is disclosed in Patent Document 1.

  The conventional photovoltaic power generation system described in Patent Document 1 includes a solar cell array including a plurality of solar cell modules, a current collection box that collects power from the solar cell array, and solar power obtained via the current collection box. And an inverter that converts DC power from the battery array into AC power. Each component is electrically connected by a cable such as a DC cable. And it becomes a structure which can replace an inverter with an alternative inverter, and the improvement of maintainability is aimed at.

JP 2011-222820 A

  However, the conventional photovoltaic power generation system described in Patent Document 1 has a problem that no special consideration is given to the cables connecting the components. That is, as the cables are merged from a large number of solar cell modules to the current collection box, the inverter, and the grid connection point, there is a concern that the current flowing through the cables becomes very large. An allowable current corresponding to the cross-sectional area of the cable is determined. If a current exceeding the allowable current is passed, the insulator covering the cable may be melted by Joule heat generated from the cable.

  On the other hand, if a cable with a large allowable current is used in anticipation of a sufficient margin, the cross-sectional area of the cable increases as the allowable current increases, that is, the wire diameter becomes relatively thick and the weight increases. This leads to a situation in which it becomes difficult to handle the cables. Therefore, the work load related to the installation of the cable may be very high.

  In addition, it is important how to arrange the components including the solar cell module so that the power generation efficiency of the solar power generation system is as high as possible in a certain occupied area.

  In particular, a large-scale photovoltaic power generation system may require a cable with a length of 50 m or more depending on the arrangement of solar cell modules. If a cable with a large cross-sectional area is used, the installation load increases and the wiring design is free. There is a risk of lowering the degree.

  Therefore, it is necessary for the photovoltaic power generation system to take care not to increase the cross-sectional area of the cable more than necessary, and to devise it so that it can be easily routed during wiring and the arrangement space can be reduced.

  The present invention has been made in view of the above points, and provides a photovoltaic power generation system that can easily handle cables during wiring, improve work efficiency, and save space. For the purpose.

  In order to solve the above problems, a photovoltaic power generation system according to the present invention includes a plurality of solar cell modules, a plurality of connection boxes electrically connected to the plurality of solar cell modules, and a plurality of the connection boxes. A current collector box connected to the inverter, an inverter electrically connected to the plurality of current collector boxes, an input terminal electrically connected to the inverter side, and an output terminal electrically connected to the grid connection point side A first step-up transformer, and a cable that is wired between each of the solar cell module, the junction box, the current collection box, and the inverter to electrically connect each of the cables to satisfy a voltage drop of 3% or less Among these cables, the cable having a longer length than the other cable has a conductor diameter smaller than that of the other cable, and the cable having a shorter length than the other cable has a conductor diameter of the other cable. It is characterized in that thicker than Bull.

  In the photovoltaic power generation system having the above-described configuration, the inverter and the current collection box are integrated. Note that the fact that the inverter and the current collection box are integrated means that they are integrated in an electric circuit, and does not simply mean that they are put together in the same box.

  Further, in the photovoltaic power generation system having the above configuration, a first cable wired between the inverter and the first step-up transformer, and a second cable wired between the first step-up transformer and the grid connection point. The second cable is characterized in that the diameter of the conductor is equal to or smaller than that of the first cable, and the thickness of the insulating coating is thicker than that of the first cable.

  In the photovoltaic power generation system having the above-described configuration, the second step-up transformer electrically connected between the first step-up transformer and the grid connection point, and between the first step-up transformer and the second step-up transformer. A fourth cable wired between a third cable to be wired and a second step-up transformer and the grid connection point, and the fourth cable has a conductor diameter equal to or smaller than the third cable, In addition, the thickness of the insulation coating is thicker than that of the third cable.

  According to the configuration of the present invention, it is possible to provide a solar power generation system that can be easily routed during cable wiring and that can improve work efficiency and save space.

It is a block diagram which shows the structure of the solar energy power generation system of 1st Embodiment of this invention. It is explanatory drawing which shows the structure of each cable of the solar energy power generation system of 1st Embodiment of this invention. It is sectional drawing of the CV cable of the solar energy power generation system of 1st Embodiment of this invention. It is sectional drawing of the CVD cable of the solar energy power generation system of 1st Embodiment of this invention. It is sectional drawing of the CVT cable of the solar energy power generation system of 1st Embodiment of this invention. It is a block diagram which shows the structure of the solar energy power generation system of 2nd Embodiment of this invention. It is explanatory drawing which shows the structure of each cable of the solar energy power generation system of 2nd Embodiment of this invention. It is a block diagram which shows the structure of the solar energy power generation system of 3rd Embodiment of this invention. It is explanatory drawing which shows the structure of each cable of the solar energy power generation system of 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

<First Embodiment>
First, the structure of the photovoltaic power generation system according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the configuration of the solar power generation system, and FIG. 2 is an explanatory diagram showing the configuration of each cable of the solar power generation system. 3, 4 and 5 are sectional views of a CV cable, a CVD cable and a CVT cable, respectively.

  As shown in FIGS. 1 and 2, the photovoltaic power generation system 1 includes a solar cell module 2, a connection box 3, a current collection box 4, an inverter 5, a feeder panel 6, an interconnection transformer 7, and a VCT (instrument transformer) 8. As a component and connected to the grid connection point CP. In FIG. 2, the description of VCT8 is omitted.

  The solar cell module 2 is configured by connecting a plurality of solar cells, which are photoelectric conversion devices that generate power using solar energy. The solar cell module 2 is installed outdoors so that it can receive direct sunlight, for example. A cable 21 is wired between the solar cell module 2 and the connection box 3 to electrically connect each of them.

  The connection box 3 is electrically connected to the plurality of solar cell modules 2 via the cable 21. The connection box 3 has a function of collecting the power generated by the solar cell module 2 and outputting it to the current collection box 4. A cable 22 is wired between the connection box 3 and the current collection box 4 to electrically connect each of them.

  The current collection box 4 is electrically connected to the plurality of connection boxes 3 through the cable 22. The current collection box 4 has a function of collecting the power output from the connection box 3 and outputting it to the inverter 5. A cable 23 is wired between the current collection box 4 and the inverter 5 to electrically connect each of them.

  The inverter 5 is electrically connected to the plurality of current collection boxes 4 via the cable 23. The inverter 5 includes a DC / AC converter (not shown) called an inverter that converts DC power to AC power. The inverter 5 has a function of collecting the DC power output from the current collection box 4, converting it to AC power, and outputting it to the feeder panel 6. A cable 24 is wired between the inverter 5 and the feeder board 6 to electrically connect each of them.

  The feeder panel 6 is electrically connected to the plurality of inverters 5 through the cable 24. The feeder panel 6 has a function of collecting the power output from the inverter 5 and outputting it to the interconnection transformer 7. A cable 25 (first cable) is wired between the feeder panel 6 and the interconnection transformer 7 to electrically connect each of them.

  The interconnection transformer 7 (first step-up transformer) has an input end electrically connected to the feeder panel 6 on the inverter 5 side, and an output end electrically connected to the grid interconnection point CP. The interconnection transformer 7 has a function of boosting the power output from the feeder panel 6 to a voltage of 6.6 kV that matches the system voltage and outputting the voltage to the system connection point CP via the VCT 8. A cable 26 (second cable) is wired between the interconnection transformer 7 and the system interconnection point CP, and is electrically connected through the VCT 8.

  Each cable described above is buried in the ground, for example, or is wired in the air by an overhead line using a steel tower.

  Moreover, the solar power generation system 1 includes a control unit (not shown). A control part controls operation | movement of each component, such as the inverter 5, based on the program and data memorize | stored previously, and implement | achieves a series of electric power supply driving | operations.

  Next, the detailed configuration of the cables 21 to 26 will be described with reference to FIGS.

  As shown in FIG. 2, the cable 21 is used at a position farthest from the grid connection point CP between the solar cell module 2 and the connection box 3, and a direct current with an operating voltage of 200 to 950 V flows. As the cable 21, for example, a DC cable such as a CV cable shown in FIG. 3 or a CVD cable shown in FIG. 4 is used.

  A CV cable (cross-linked polyethylene insulated vinyl sheath cable, FIG. 3) is a copper conductor 51 covered with a cross-linked polyethylene insulator 52 having a thickness of 3.0 to 6.0 mm, and the outside thereof is further coated with a thickness of 1.5 to A sheath 53 made of heat-resistant polyethylene of 5.0 mm is covered. In the CVD cable (FIG. 4), each of the two conductors 51 is individually covered with an insulator 52 and a sheath 53.

The cable 21 has a length of 2 to 100 m, and the conductor 51 has a diameter (cross-sectional area) of 1.5 to 3.5 mm ² .

The cable 22 is used between the connection box 3 and the current collection box 4 at a location closer to the grid connection point CP than the cable 21, and a direct current with an operating voltage of 200 to 950 V flows. As the cable 22, for example, a DC cable such as a CV cable or a CVD cable is used. The cable 22 has a length of 5 to 100 m, and the conductor 51 has a diameter (cross-sectional area) of 3.5 to 38 mm ² .

The cable 23 is used between the current collection box 4 and the inverter 5 at a location closer to the grid connection point CP than the cable 22, and a direct current with an operating voltage of 200 to 950 V flows. As the cable 23, for example, a DC cable such as a CV cable or a CVD cable is used. The cable 23 has a length of 5 to 100 m, and the conductor 51 has a diameter (cross-sectional area) of 3.5 to 150 mm ² .

  The cable 24 is used between the inverter 5 and the feeder panel 6 at a location closer to the system interconnection point CP than the cable 23, and an alternating current with an operating voltage of 200 to 600 V flows. As the cable 24, for example, an AC cable such as a CVT cable shown in FIG. 5 is used.

  In the CVT cable (FIG. 5), the three conductors 51 are individually coated in the order of the semiconductive layer 54, the insulator 52, the semiconductive layer 55, and the shielding layer 56. Then, these three are adjacent to each other and the outside is covered with the tape 57 and the sheath 53, and the inclusion 58 is filled in the gap inside the sheath 53 so as to have a circular cross section.

The cable 24 has a length of 5 to 500 m, and the conductor 51 has a diameter (cross-sectional area) of 22 to 325 mm ² .

The cable 25 (first cable) is used between the feeder board 6 and the interconnection transformer 7 at a location closer to the system interconnection point CP than the cable 24, and an alternating current with an operating voltage of 200 to 600 V flows. As the cable 25, for example, an AC cable such as a CVT cable is used. The cable 25 has a length of 0.1 to 15 km, and the conductor 51 has a diameter (cross-sectional area) of 22 to 325 mm ² .

The cable 26 (second cable) is used at a location closer to the system interconnection point CP than the cable 25 between the interconnection transformer 7 and the system interconnection point CP, and an AC current having an operating voltage of 6.6 kV flows. As the cable 26, for example, an AC cable such as a CVT cable is used. The cable 26 has a length of 0.1 to 15 km, and the conductor 51 has a diameter (cross-sectional area) of 22 to 325 mm ² . In the cable 26, the diameter of the conductor 51 is not more than the cable 25, and the thickness of the insulating coating (insulator 52) is thicker than that of the cable 25.

  The above cables are selected so that the voltage drop from the start point to the end point satisfies 3% (more strictly within 2%). The voltage drop e due to the cable can be calculated by equation (1).

e = K × I × (r × cos θr + X × sin θr) × L (1)
e: Voltage drop [V]
K: Coefficient according to wiring system I: Energizing current [A]
r: AC conductor resistance per 1 km of cable [Ω / km]
X: Reactance per 1 km of cable [Ω / km]
cos θr: Load end power factor L: Length of line [km]

  The voltage drop e for each of the DC side and AC side is calculated by the formula (1), and the conductor of the cable used so that these voltage drops e satisfy within 3% (or within 2%) of each of the DC side and AC side. Select the diameter. In addition, when the specification relating to the voltage drop e is satisfied, if a cable having a thicker conductor is used, the electrical resistance is further lowered. Therefore, it is possible to improve the power transmission efficiency and the power generation efficiency of the photovoltaic power generation system. it can.

In addition, the solar power generation system 1 of 1st Embodiment corresponds to the system scale of the DC2000kW solar power generation system shown below, for example. The system scale is
Site area: 26,400-30,000 m ²
Number of installed modules: 6,800-15,700
Number of connection boxes: 60 to 100 units
Number of current collection boxes: 7-20
Number of inverters: 1 to 20 units.

  This configuration is an example, and in recent years, there are many inverters having a function of a current collection box, and the present invention is not limited to this configuration.

  Here, the plurality of cables 21 to 23 in FIG. 2 have greatly different path lengths depending on the arrangement of the constituent elements of the solar power generation system 1. For example, the cable 21 connecting the solar cell module 2 and the junction box 3 has a path length that is significantly different from 2 to 100 m.

  The solar power generation system 1 suitably arranges each component in order to increase the amount of power generation within a predetermined site, and performs routing accordingly when wiring cables. As mentioned above, the cable wiring will be buried underground or overhead. Thereby, as the diameter of the cable increases and the volume and weight increase, the load applied to the installation increases and the cost also increases. Moreover, since it becomes difficult to bend a cable with a thicker diameter, the freedom degree of the wiring at the time of wiring will also fall. This effect becomes more prominent as the wiring length is longer.

  Therefore, in the photovoltaic power generation system 1 of the present invention, a cable having a longer distance satisfies the above voltage drop of 3% and uses a cable having a diameter as small as possible, and conversely, a cable having a shorter distance has a larger diameter. It is characterized in that power generation efficiency is improved by using cables.

For example, in the cable 22 of FIGS. 1 and 2, when the path length is 100 m and the maximum voltage is 950 V, a cable with a diameter of 3.5 mm ² is used as much as possible while satisfying a voltage drop of 3% or less, and the path length is 5 m. When the load is low, a cable as thick as possible with a diameter of 3.5 mm ² or more, for example, a cable with a diameter of 22 mm ² is used.

Second Embodiment
Next, the solar power generation system of 2nd Embodiment of this invention is demonstrated using FIG.6 and FIG.7. FIG. 6 is a block diagram showing the configuration of the solar power generation system, and FIG. 7 is an explanatory diagram showing the configuration of each cable of the solar power generation system. Since the basic configuration of this embodiment is the same as that of the first embodiment described with reference to FIGS. 1 to 5, the same reference numerals are assigned to the same components as those of the first embodiment. The description of the drawings and the description thereof will be omitted.

  As shown in FIGS. 6 and 7, the photovoltaic power generation system 1 of the second embodiment includes a first step-up transformer 9 (first step-up transformer) and a second step between the feeder panel 6 and the interconnection transformer 11. An up transformer 10 (second step-up transformer) is provided as a component.

  The first step-up transformer 9 has its input end connected to the output end of a single feeder panel 6, and the second step-up transformer 10 has its input end connected to the output ends of a plurality of first step-up transformers 9. Collect power. The first step-up transformer 9 and the second step-up transformer 10 increase the power stepwise to increase the power output from the feeder panel 6 to a voltage that matches the system voltage. It has the function to output to.

  A cable 35 is wired between the feeder panel 6 and the first step-up transformer 9 to electrically connect them. A cable 36 (third cable) is wired between the first step-up transformer 9 and the second step-up transformer 10 to electrically connect each of them. A cable 37 (fourth cable) is wired between the second step-up transformer 10 and the interconnection transformer 11 to electrically connect each of them.

  Next, the detailed configuration of the cables 31 to 38 will be described with reference to FIG.

As shown in FIG. 7, the cable 31 is used at a position farthest from the grid connection point CP between the solar cell module 2 and the connection box 3, and a direct current with an operating voltage of 200 to 950 V flows. As the cable 31, for example, a DC cable such as a CV cable shown in FIG. 3 or a CVD cable shown in FIG. 4 is used. The cable 31 has a length of 2 to 100 m, and the conductor 51 has a diameter (cross-sectional area) of 1.5 to 3.5 mm ² .

The cable 32 is used between the connection box 3 and the current collection box 4 at a location closer to the grid connection point CP than the cable 31, and a direct current with an operating voltage of 200 to 950 V flows. As the cable 32, for example, a DC cable such as a CV cable or a CVD cable is used. The cable 32 has a length of 5 to 100 m, and the conductor 51 has a diameter (cross-sectional area) of 3.5 to 38 mm ² .

The cable 33 is used at a location closer to the grid connection point CP than the cable 32 between the current collection box 4 and the inverter 5, and a direct current with an operating voltage of 200 to 950 V flows. As the cable 33, for example, a DC cable such as a CV cable or a CVD cable is used. The cable 33 has a length of 5 to 100 m, and the conductor 51 has a diameter (cross-sectional area) of 3.5 to 38 mm ² .

The cable 34 is used between the inverter 5 and the feeder panel 6 at a location closer to the system interconnection point CP than the cable 33, and an alternating current with an operating voltage of 200 to 600 V flows. As the cable 34, for example, an AC cable such as a CVT cable shown in FIG. 5 is used. The cable 34 has a length of 5 to 500 m, and the conductor 51 has a diameter (cross-sectional area) of 22 to 325 mm ² .

The cable 35 is used at a location closer to the grid connection point CP than the cable 34 between the feeder panel 6 and the first step-up transformer 9, and an alternating current with an operating voltage of 200 to 600 V flows. As the cable 35, for example, an AC cable such as a CVT cable is used. The cable 35 has a length of 5 to 500 m, and the conductor 51 has a diameter (cross-sectional area) of 22 to 325 mm ² .

The cable 36 (third cable) is used between the first step-up transformer 9 and the second step-up transformer 10 at a location closer to the grid connection point CP than the cable 35, and has an operating voltage of 6.1 to 6.8 kV. AC current flows. As the cable 36, for example, an AC cable such as a CVT cable is used. The cable 36 has a length of 0.3 to 15 km, and the conductor 51 has a diameter (cross-sectional area) of 22 to 325 mm ² .

The cable 37 (fourth cable) is used at a location closer to the system interconnection point CP than the cable 36 between the second step-up transformer 10 and the interconnection transformer 11, and an alternating current having an operating voltage of 21 to 78 kV flows. As the cable 37, for example, an AC cable such as a CVT cable is used. The cable 37 has a length of 0.3 to 15 km, and the conductor 51 has a diameter (cross-sectional area) of 22 to 250 mm ² . In the cable 37, the diameter of the conductor 51 is equal to or smaller than the cable 36, and the thickness of the insulating coating (insulator 52) is thicker than that of the cable 36.

The cable 38 is used between the interconnection transformer 11 and the grid connection point CP at a location closer to the grid connection point CP than the cable 37, and an alternating current with an operating voltage of 21 to 78 kV flows. As the cable 38, for example, an AC cable such as a CVT cable is used. The cable 38 has a length of 0.3 to 15 km, and the conductor 51 has a diameter (cross-sectional area) of 22 to 250 mm ² .

<Third Embodiment>
Next, the solar power generation system of 3rd Embodiment of this invention is demonstrated using FIG.8 and FIG.9. FIG. 8 is a block diagram showing the configuration of the solar power generation system, and FIG. 9 is an explanatory diagram showing the configuration of each cable of the solar power generation system. Since the basic configuration of this embodiment is the same as that of the first embodiment described with reference to FIGS. 1 to 5, the same reference numerals are assigned to the same components as those of the first embodiment. The description of the drawings and the description thereof will be omitted.

  As shown in FIGS. 8 and 9, the photovoltaic power generation system 1 of the third embodiment includes a connection box 3 as a component between the solar cell module 2 and the inverter 5, and the inverter 5 and the interconnection transformer 13 A step-up transformer 12 (first step-up transformer) is provided as a component in between. The interconnection transformer 13 is connected to the output side of the plurality of step-up transformers 12 and collects power.

  The inverter 5 is configured by integrating an electric circuit having an original function of the inverter and an electric circuit having a current collecting function. That is, the inverter 5 is integral with the current collection box.

  A cable 43 (first cable) is wired between the inverter 5 and the step-up transformer 12 to electrically connect each of them. A cable 44 (second cable) is wired between the step-up transformer 12 and the interconnection transformer 13 to electrically connect each of them.

  Next, the detailed configuration of the cables 41 to 45 will be described with reference to FIG.

As shown in FIG. 9, the cable 41 is used at a position farthest from the grid connection point CP between the solar cell module 2 and the connection box 3, and a direct current with an operating voltage of 200 to 950 V flows. As the cable 41, for example, a DC cable such as a CV cable shown in FIG. 3 or a CVD cable shown in FIG. 4 is used. The cable 41 has a length of 2 to 100 m, and the conductor 51 has a diameter (cross-sectional area) of 1.5 to 3.5 mm ² .

The cable 42 is used between the connection box 3 and the inverter 5 at a location closer to the grid connection point CP than the cable 41, and a direct current with an operating voltage of 200 to 950 V flows. As the cable 42, for example, a DC cable such as a CV cable or a CVD cable is used. The cable 42 has a length of 5 to 100 m, and the conductor 51 has a diameter (cross-sectional area) of 3.5 to 38 mm ² .

The cable 43 (first cable) is used between the inverter 5 and the step-up transformer 12 at a location closer to the grid connection point CP than the cable 42, and an AC current having an operating voltage of 200 to 600 V flows. As the cable 43, for example, an AC cable such as a CVT cable shown in FIG. 5 is used. The cable 43 has a length of 5 to 500 m, and the conductor 51 has a diameter (cross-sectional area) of 22 to 325 mm ² .

The cable 44 (second cable) is used at a location closer to the system interconnection point CP than the cable 43 between the step-up transformer 12 and the interconnection transformer 13, and an alternating current with an operating voltage of 21 to 78 kV flows. As the cable 44, for example, an AC cable such as a CVT cable is used. The cable 44 has a length of 0.1 to 15 km, and the conductor 51 has a diameter (cross-sectional area) of 22 to 250 mm ² . In the cable 44, the diameter of the conductor 51 is equal to or smaller than the cable 43, and the thickness of the insulating coating (insulator 52) is thicker than that of the cable 43.

The cable 45 is used between the interconnection transformer 13 and the grid connection point CP at a location closer to the grid connection point CP than the cable 44, and an alternating current with an operating voltage of 21 to 78 kV flows. As the cable 45, for example, an AC cable such as a CVT cable is used. The cable 45 has a length of 0.1 to 15 km, and the conductor 51 has a diameter (cross-sectional area) of 22 to 250 mm ² .

  As described above, the photovoltaic power generation system 1 includes a plurality of solar cell modules 2, a plurality of connection boxes 3 that are electrically connected to the plurality of solar cell modules 2, and a collection that is electrically connected to the plurality of connection boxes 3. The electrical box 4, the inverter 5 electrically connected to the plurality of current collection boxes 4, the input end electrically connected to the inverter 5 side, and the output end electrically connected to the grid connection point CP side 1 step-up transformer (interconnection transformer 7, first step-up transformer 9 or step-up transformer 12). The cables that are wired between the solar cell module 2, the connection box 3, the current collection box 4 and the inverter 5 to electrically connect each of them are cables that satisfy a voltage drop of 3% or less. Among these cables, A cable having a longer length than other cables has a conductor 51 having a smaller diameter than the other cables, and a cable having a shorter length than other cables has a conductor 51 having a larger diameter than the other cables.

  According to this configuration, the cables 21, 31, 41 connected to the solar cell module 2 have a relatively small cross-sectional area when there is a possibility that the installation load becomes large at a long distance between the components, that is, the conductor 51 The diameter can be made relatively thin. Therefore, it becomes easy to handle the cable when wiring the solar cell module 2 and the space occupied by the cable can be reduced. Further, when the cables are easily routed between the constituent elements at a short distance, a cable having a diameter of the conductor 51 that is as large as possible within the allowable range of cost and installation load can be used without being limited by the voltage drop within 3%. Thereby, it is possible to improve the transmission efficiency of electricity.

  Moreover, in 3rd Embodiment, the solar power generation system 1 has the inverter 5 and the current collection box integrated.

  According to this configuration, it is not necessary to wire a cable between the inverter 5 and the current collection box, and it is not necessary to consider the handling when the cable is wired. Therefore, the working efficiency related to the installation of the cable is improved, and space saving can be achieved. Moreover, since there is no voltage drop between the inverter 5 and the current collection box, it is possible to suppress a reduction in power transmission efficiency.

  In the first and third embodiments, the photovoltaic power generation system 1 includes a first cable (the cable 25 or the cable) wired between the inverter 5 and the first step-up transformer (the interconnection transformer 7 or the step-up transformer 12). 43) and a second cable (cable 26 or cable 44) wired between the first step-up transformer and the grid connection point CP. In the second cable, the diameter of the conductor 51 is equal to or smaller than that of the first cable, and the thickness of the insulator 52 is thicker than that of the first cable.

  According to this configuration, since electricity is increased in voltage by the first step-up transformer, the diameter of the conductor 51 in the second cable can be made smaller than that in the first cable. Therefore, it is possible to easily handle the cables when wiring them, and it is possible to improve work efficiency and save space. In addition, although there is a concern about the insulation of the second cable due to the increase in voltage of electricity, it is possible to ensure the insulation of the second cable by making the insulating coating thicker than the first cable.

  In the second embodiment, the photovoltaic power generation system 1 includes a second step-up transformer (second step) electrically connected between the first step-up transformer (first step-up transformer 9) and the grid connection point CP. Up transformer 10), a third cable (cable 36) wired between the first boost transformer and the second boost transformer, and a fourth cable wired between the second boost transformer and the grid connection point. A cable (cable 37). In the fourth cable, the diameter of the conductor 51 is equal to or smaller than the third cable, and the thickness of the insulator 52 is thicker than that of the third cable.

  According to this configuration, since electricity is increased in voltage by the second step-up transformer, the diameter of the conductor 51 in the fourth cable can be made smaller than that in the third cable. Therefore, it is possible to easily handle the cables when wiring them, and it is possible to improve work efficiency and save space. Although there is a concern about the insulation of the fourth cable due to the increase in the voltage of electricity, it is possible to ensure the insulation of the fourth cable by making the insulating coating thicker than the third cable.

  Thus, according to the configuration of the above-described embodiment of the present invention, the solar power generation system 1 can be easily routed at the time of cable wiring, and the working efficiency is improved and the space is saved. Can be provided.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention can be used in a photovoltaic power generation system.

DESCRIPTION OF SYMBOLS 1 Photovoltaic power generation system 2 Solar cell module 3 Connection box 4 Current collection box 5 Inverter 6 Feeder board 7 Interconnection transformer (1st step-up transformer)
8 VCT
9 First step-up transformer (first step-up transformer)
10 Second step-up transformer (second step-up transformer)
11 Interconnection transformer 12 Step-up transformer (first step-up transformer)
13 interconnection transformer 21-24, 31-35, 38, 41, 42, 45 Cable 25, 43 1st cable 26, 44 2nd cable 36 3rd cable 37 4th cable 51 Conductor 52 Insulator (insulation film)

Claims (4)

A plurality of solar cell modules;
A plurality of junction boxes electrically connected to the plurality of solar cell modules;
A current collection box electrically connected to the plurality of junction boxes;
An inverter electrically connected to the plurality of current collection boxes;
A first step-up transformer whose input terminal is electrically connected to the inverter side and whose output terminal is electrically connected to the grid connection point side;
With
Cables that are wired between each of the solar cell module, the junction box, the current collection box, and the inverter to electrically connect each of them are cables that satisfy a voltage drop of 3% or less, and among these cables, A solar cable characterized in that a cable having a longer length than other cables has a conductor diameter smaller than that of the other cables, and a cable having a shorter length than other cables has a conductor diameter larger than that of the other cables. Power generation system.   The solar power generation system according to claim 1, wherein the inverter and the current collection box are integrated. A first cable to be wired between the first step-up transformer and the inverter,
A second cable wired between the first step-up transformer and the grid connection point;
With
The second cable is a diameter of the conductor is less than the first cable, and solar power generation system according to claim 1 or 2 the thickness of the insulating coating, characterized in that thicker than said first cable . A second step-up transformer electrically connected between the first step-up transformer and the grid connection point;
A third cable is wired between the second step-up transformer and the first step-up transformer,
A fourth cable wired between the second step-up transformer and the grid connection point;
With
It said fourth cable is a diameter of the conductor is less than the third cable, and solar power generation system according to claim 1 or 2 the thickness of the insulating coating is characterized thicker than the third cable .

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