JPWO2019021449A1 - Photovoltaic power generation system and grounding method thereof - Google Patents

Abstract

The photovoltaic power generation system converts DC power supplied from the first solar cell array, the second solar cell array, and the first solar cell array and the second solar cell array into AC power, and a ground electrode. A power conditioner connected to the first solar cell array and the ground electrode, a first ground line connecting the first solar cell array and the ground electrode, and one end connected to the second solar cell array and the other end connected to the ground electrode or the first A second ground line connected to the ground line. The ground line group connects each of the plurality of solar cell arrays directly to one ground pole with a plurality of ground lines without intervening another solar cell array.

Description

  The present invention relates to a photovoltaic power generation system and a grounding method thereof.

  Conventionally, it is known to ground a solar cell as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-297976. This publication considers electromagnetic noise associated with switching of the inverter circuit as a problem. This publication discloses a technique for forming the side plate with a metal material so that the side plate of the solar cell module can absorb electromagnetic waves.

Japanese Unexamined Patent Publication No. 2-297976

  The inventor of the present application has been diligently researching EMC countermeasures in a photovoltaic power generation system. Among them, measures against high-frequency noise generated from the power conditioner are necessary. When high frequency noise is applied to the input side wiring and the output side wiring of the inverter, the noise follows various noise transmission paths. When a part of the noise reaches the power transmission line via various noise transmission paths, there is a problem that various radio interferences are caused. As a countermeasure, it may be possible to insert a filter circuit in the input side wiring and the output side wiring. However, there is a problem in that there is a great disadvantage in terms of cost increase.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a photovoltaic power generation system and a grounding method thereof that can suppress radio wave interference due to high-frequency current noise.

The photovoltaic power generation system according to the first invention of the present application is
A first solar cell array;
A second solar cell array;
A power conditioner that converts DC power supplied from the first solar cell array and the second solar cell array into AC power and is connected to a ground electrode;
A first ground line connecting the first solar cell array and the ground electrode;
A second ground wire having one end connected to the second solar cell array and the other end connected to the ground electrode or the first ground wire;
Is provided.

The photovoltaic power generation system according to the second invention of the present application is
A plurality of solar cell arrays;
A power conditioner that converts DC power supplied from the plurality of solar cell arrays into AC power and is connected to a ground electrode;
Each of the plurality of solar cell arrays, without interposing another solar cell array, a ground wire group that is directly connected to one ground electrode with a plurality of ground wires,
Is provided.

The grounding method of the photovoltaic power generation system according to the third invention of the present application is as follows:
DC power supplied from a first solar cell array having a plurality of first solar cells, a second solar cell array having a plurality of second solar cells, and the first solar cells and the second solar cells is exchanged. Preparing a solar power generation system comprising a power conditioner for converting to electric power,
Connect the grounding electrode and the inverter.
Connecting the grounding electrode and the first solar cell array with a first grounding wire;
One end of the second ground line is connected to the second solar cell array, and the other end of the second ground line is connected to the ground electrode or the first ground line.

  According to the present invention, each of the plurality of solar cell arrays is connected to the ground electrode via the ground line without interposing another solar cell array therebetween. As a result, the impedance between each solar cell array and the ground electrode can be lowered, so that high-frequency current noise can be made to flow as easily as possible to the ground electrode. As a result, it is possible to suppress radio wave interference by suppressing stray radio frequency current noise.

It is a figure which shows the outline of the photovoltaic power generation system concerning embodiment of this invention, and its grounding method. It is a figure which shows the outline of the other photovoltaic power generation system concerning embodiment of this invention, and its grounding method. It is a figure which shows the detailed structure of the solar energy power generation system concerning embodiment of this invention, and its grounding method. It is a figure which shows the outline of the photovoltaic power generation system concerning embodiment of this invention, and its grounding method. It is a figure which shows the modification of the solar energy power generation system concerning embodiment of this invention, and its grounding method. It is a figure which shows the modification of the solar energy power generation system concerning embodiment of this invention, and its grounding method. It is a figure which shows the modification of the solar energy power generation system concerning embodiment of this invention, and its grounding method. It is a figure which shows the modification of the solar energy power generation system concerning embodiment of this invention, and its grounding method. It is a figure which shows the outline of the photovoltaic power generation system concerning the comparative example with respect to embodiment, and its grounding method. It is a figure for demonstrating the problem of the high frequency current noise which generate | occur | produces in a power conditioner. It is a figure for demonstrating the problem of the high frequency current noise which generate | occur | produces in a power conditioner.

  10 and 11 are diagrams for explaining the problem of high-frequency current noise that occurs in the power conditioner. FIG. 10 shows a photovoltaic power generation system 100 as a comparative example with respect to the embodiment. The photovoltaic power generation system 100 includes a plurality of solar cell arrays 1a and 1b, a current collection box 30, a power conditioner 32, a plurality of PV system grounding electrodes 20, a high voltage panel 34, a high voltage panel grounding electrode 24, The contact prevention grounding electrode 22, a plurality of grounding wires 9, and a PAS (Pole Air Switch) 36 are provided.

  Each of the solar cell arrays 1 a and 1 b includes a gantry 3 and a solar cell panel 2 attached to the gantry 3. Electric cables extending from each of the solar cell arrays 1 a and 1 b are collected in a current collection box 30. The current collection box 30, the power conditioner 32, the high voltage board 34, and the PAS 36 are connected in series in this order.

  In each solar cell array 1a, 1b, the solar cell panel 2 is grounded to the mount 3. The gantry 3 of the solar cell array 1 a and the gantry 3 of the solar cell array 1 b are connected via a ground wire 9. The mount 3 of the solar cell array 1a is grounded to one of the plurality of PV system grounding electrodes 20. The current collection box 30 and the power conditioner 32 are grounded to the plurality of PV system grounding electrodes 20 via the plurality of grounding wires 9, respectively. The high voltage board 34 includes a transformer 33. The high-voltage board 34 is grounded by the high-voltage board grounding electrode 24 and the mixed contact prevention grounding electrode 22 through a plurality of grounding wires 9. The PAS 36 is connected to the power transmission line 39 via the lead-in pillar 38.

  FIG. 11 illustrates the airborne capacitance Cf associated with the device of the photovoltaic power generation system 100 illustrated in FIG. In FIG. 11, a plurality of noise transmission paths are also shown by broken-line arrows. The power conditioner 32 generates high-frequency current noise due to the switching operation of the built-in inverter circuit. The high-frequency current noise is transmitted to the input side of the power conditioner 32, that is, the system DC side, and is also transmitted to the output side of the power conditioner 32, that is, the system AC side. The high-frequency current noise tends to return to the power conditioner 32 that is a generation source. However, as shown in FIG. 11, each device of the photovoltaic power generation system 100 has an airborne capacitance Cf between itself and the ground. High-frequency current noise is transmitted through various noise transmission paths via the air floating capacitance Cf.

  As an example of the noise transmission path, there is a path where high-frequency current noise generated via the air floating capacitance Cf on the system DC side returns to the power conditioner 32 via the ground. As another example of the noise transmission path, a path in which high-frequency current noise generated via the air floating capacitance Cf on the system DC side returns to the power conditioner 32 via the ground and the transformer 33 in the high voltage board 34. There is. As still another example of the noise transmission path, there is a path in which high-frequency current noise generated via the air floating capacitance Cf on the system DC side exits to the transmission line 39 via the ground, the PAS 36, and the lead-in pillar 38. As still another example of the noise transmission path, there is a path in which high-frequency current noise reaching the power transmission line 39 returns to the power conditioner 32 via the lead-in column 38, the PAS 36, and the high-voltage board 34.

  Various noise transmission paths include a “correct noise feedback path” in which no noise radio waves are generated. An example of a correct noise feedback path is a path that reciprocates a main circuit conductor that connects the power conditioner 32 and the solar cell arrays 1a and 1b. Another example of a correct noise feedback path is a path that reciprocates the main circuit conductor connecting the power conditioner 32 and the high voltage board 34. Still another example of the correct noise feedback path is that the base 3, the current collecting box 30, and the high voltage board 34 reach the ground via the ground wire 9 and further return from the ground to the power conditioner 32 via the ground wire 9. It is a route to do. Noise flowing through these paths is normal mode noise.

  On the other hand, the noise transmission path includes a path for generating noise radio waves. This is a path through which high-frequency current noise is not correctly fed back due to stray high-frequency current noise. Specifically, noise radio waves are generated due to a leakage current flowing from the main circuit conductor via the airborne capacitance Cf. This is common mode noise. Let us pay attention to, for example, the noise transmission path Ix in FIG. 11 among various noise transmission paths. The noise transmission path Ix is a path that follows the airborne capacitance Cf of the solar cell array 1a, the ground, the high-voltage board grounding electrode 24, the high-voltage board 34, the PAS 36, the pull-in column 38, the transmission line 39, and the floating capacitance Cf of the transmission line 39. is there. In the noise transmission path Ix, high-frequency current noise reaching the power transmission line 39 further flows via the airborne capacitance Cf between the power transmission line 39 and the ground. At this time, electromagnetic waves may be generated, which may cause radio interference in neighboring houses or cars. This electromagnetic wave is a factor that greatly affects radio interference.

  FIG. 1 is a diagram schematically illustrating a photovoltaic power generation system 10 and a grounding method thereof according to an embodiment of the present invention. The photovoltaic power generation system 10 according to the embodiment includes a plurality of solar cell arrays 1 a to 1 d, a power conditioner 32, a PV system ground electrode 20, and a plurality of ground wires 9. The power conditioner 32 converts the DC power supplied from the plurality of solar cell arrays 1a and 1b into AC power. The power conditioner 32 is connected to the PV system ground electrode 20 via the ground wire 9.

  Here, for convenience, the solar cell array 1a is also referred to as “first solar cell array 1a”, and the solar cell array 1b is also referred to as “second solar cell array 1b”. For convenience, the ground line 9 connected to the first solar cell array 1a is also referred to as "first ground line 9a", and the ground line 9 connected to the second solar cell array 1b is also referred to as "second ground line 9b". In the photovoltaic power generation system 10 shown in FIG. 1, one end of the second ground line 9 b is connected to the second solar cell array 1 b, and the other end of the second ground line 9 b is connected to the PV system ground electrode 20. Similarly to the second solar cell array 1b, the solar cell arrays 1c and 1d are also directly connected to the PV system ground electrode 20 via the ground wire 9.

  FIG. 2 is a diagram showing an outline of another photovoltaic power generation system 10 and its grounding method according to the embodiment of the present invention. In the photovoltaic power generation system 10 shown in FIG. 2, one end of the second ground line 9b is connected to the second solar cell array 1b, and the other end of the second ground line 9b is connected to the first ground line 9a. That is, the second ground line 9b branches off from the middle of the first ground line 9a. Similarly to the second solar cell array 1b, the solar cell arrays 1c and 1d are also connected to the PV system ground electrode 20 via a network of branched ground wires 9.

  In the embodiment shown in FIGS. 1 and 2, each of the plurality of solar cell arrays 1a and 1b is connected to the PV system ground electrode 20 via the plurality of ground wires 9 without interposing another solar cell array therebetween. Is done. As a result, the electrical path between each of the solar cell arrays 1a, 1b and the PV system ground electrode 20 can be shortened, and high-frequency current noise can be made to flow as easily as possible in the PV system ground electrode 20. As a result, it is possible to suppress radio wave interference by suppressing stray radio frequency current noise.

  FIG. 9 is a diagram illustrating an outline of a photovoltaic power generation system 100 and a grounding method according to a comparative example with respect to the embodiment. In the grounding method in the conventional photovoltaic power generation system, a plurality of solar cell arrays 1 a to 1 d are connected in series via a plurality of ground lines 9. FIG. 9 illustrates such a grounding method by serial connection. The solar cell array 1 a at the end of the plurality of solar cell arrays 1 a to 1 d connected in series is connected to the current collection box 30. The grounding operation is completed by connecting the current collecting box 30 and the PV system grounding electrode 20. The function required for the grounding wire 9 is sufficient to pass a direct current to prevent electric shock. Conventionally, only solar cell arrays 1a and 1d are connected in series with each other via a grounding wire 9. This is because workability is high because the adjacent solar cell arrays 1a to 1d need only be connected by the ground line 9, and series connection is sufficient from the viewpoint of preventing electric shock.

  However, when the ground wire 9 is connected in series as shown in FIG. 9, the solar cell array 1 d located at the end of the plurality of solar cell arrays 1 a to 1 d is closer to the PV system ground electrode 20. The electric path becomes long. As a result, the high impedance makes it difficult for the high frequency current noise to flow to the PV system ground electrode 20, but rather the high frequency current noise tends to leak to the ground via the air floating capacitance Cf. In this regard, in the embodiment shown in FIGS. 1 and 2, the electrical path between each of the solar cell arrays 1a to 1d and the PV system ground electrode 20 can be shortened, and the impedance between them can be made sufficiently low. . Therefore, the ability to collect high-frequency current noise to the PV system ground electrode 20 can be dramatically increased.

In the embodiment, it is preferable to make the wire cross-sectional area of the ground wire 9 thicker than 2 mm ² . The thickness of the grounding cable is determined to be a jump value by the standard. Specifically, the standard value of the wire cross-sectional area that determines the thickness of the grounding cable is 2 mm ² , 3.8 mm ² , 5.5 mm ² , 8 mm ² , 14 mm ² , 22 mm ² , 38 mm ² , 60 mm ² , and It is determined to be 100 mm ² . When the prior art strand cross-sectional area considering only prevent an electric shock is given that has been used for grounding cable 2 mm ^2, thick 3.8 mm ² or more ground one step more than 2 mm ² in the embodiment More preferably, a cable is used for the ground wire 9. More preferably, wire cross-sectional area may be used to ground line 9 as possible thick cable of the cable 3.8 mm ² 100 mm ^2. A cable having a cross-sectional area thicker than 100 mm ² can also be used for the grounding wire 9.

Here, the thickness of the grounding cable will be described. The role of the grounding wire 9 in the prior art described with reference to FIGS. 9 to 11 is to flow a DC voltage to the ground to prevent electric shock. Therefore, in the prior art described with reference to FIGS. 9 to 11, the grounding wire 9 is basically sufficient even with a thickness of 2 mm ² or less. If an unnecessarily thick cable is used, it becomes difficult to handle due to an increase in cost, weight, and the like. Therefore, if considering only prevention of electric shock, such a thin cable may be used. On the other hand, since the high-frequency current is affected by the skin effect, the high-frequency current flows only on the surface of the conductor. Therefore, there is a problem that high-frequency current noise hardly flows when the conventional simple electric shock prevention grounding wire is used. In consideration of such points, in the embodiment, the grounding wire 9 is preferably a cable having a strand cross-sectional area of 3.8 mm ² or more. All of the grounding wires 9 connected to one PV system grounding electrode 20 may be cables each having a strand cross-sectional area of 3.8 mm ² or more.

  FIG. 3 is a diagram showing a detailed structure of the photovoltaic power generation system 10 and its grounding method according to the embodiment of the present invention. The solar power generation system 10 includes a plurality of solar cell arrays 1a to 1h, a plurality of connection boxes 4, a current collection box 30, a power conditioner 32, a PV system ground electrode 20, and a plurality of ground lines 9, 40. , 42, a high voltage board 34, a high voltage board ground electrode 24, a mixed contact prevention ground electrode 22, and a PAS 36.

  Each of the solar cell arrays 1 a to 1 h includes a gantry 3 and a plurality of solar cell panels 2 attached to the gantry 3. Each of the solar battery panels 2 incorporates a plurality of solar battery cells. The power conditioner 32 includes an inverter circuit that converts input DC power into AC power. The inverter circuit includes a plurality of semiconductor switching elements. When the semiconductor switching element performs a switching operation by the high frequency signal, the power conditioner 32 becomes a source of high frequency current noise. Although not shown, the high voltage board 34 incorporates a transformer 33 as shown in FIG. The PAS 36 is an air load switch.

  As shown by a solid line in FIG. 3, each device included in the solar power generation system 10 is electrically connected by a plurality of electric cables. The plurality of solar cell panels 2 included in each of the solar cell arrays 1a to 1h are connected in series by electric cables. Each of the solar cell arrays 1a to 1h and the plurality of connection boxes 4 are connected via electric cables. A plurality of connection boxes 4 are connected to one current collection box 30 via electric cables. The current collection box 30 and the power conditioner 32 are connected via an electric cable. The power conditioner 32, the high voltage board 34, and the PAS 36 are connected in series via an electric cable. The PAS 36 is connected to a drawing column 38 via an electric cable, and a power transmission line 39 extends from the drawing column 38.

  The types of conventional grounding work include A type, B type, C type, and D type. In the embodiment, each grounding structure is used as follows. The PV system grounding electrode 20 is preferably A-type or C-type grounding. The high-voltage board grounding electrode 24 is preferably A-type grounding. The mixed contact prevention ground electrode 22 is preferably a B-type ground. The distance X1 between the PV system ground electrode 20 and the high-voltage panel ground electrode 24 is preferably 20 m or more. It is preferable that the distance X2 between the PV system grounding electrode 20 and the incompatibility preventing grounding electrode 22 is 20 m or more.

  Types A to D in the above-described grounding system are defined in “Article 17 Interpretation of Technical Standards for Electrical Equipment” in Japan. The following table shows the grounding method.

  Next, the connection structure of the ground wires 9, 40, and 42 in the solar power generation system 10 will be described. First, “Definition of terms in the embodiment” will be described. In the embodiment, the plurality of ground lines 9, 40, and 42 for grounding the photovoltaic power generation system 10 can be classified into a “ground trunk line” and a “ground branch line”. The “ground trunk line” according to the embodiment is a ground line that is a main route among the plurality of ground lines 9, 40, and 42. Further, the “ground branch line” according to the embodiment is a ground line that branches from the ground trunk line and is connected to any one of the solar cell arrays 1a to 1h. In the following description, the ground lines 40 and 42 are also referred to as “ground trunk lines 40 and 42”, and the ground line 9 branched from the ground trunk lines 40 and 42 is also referred to as “ground branch line 9”.

  In the embodiment shown in FIG. 3, the solar cell arrays 1 a to 1 h, the connection box 4, and the current collection box 30 are connected to one of the two ground trunk lines 40 and 42 via the plurality of ground branch lines 9. ing. Each of the ground trunk lines 40 and 42 is grounded by connecting to the PV system ground electrode 20. The power conditioner 32 is connected to the PV system ground electrode 20 through the ground wire 9. As described above, the photovoltaic power generation system 10 according to the embodiment performs grounding by the “trunk system” using the ground trunk line and the ground branch line. The high-voltage board 34 is grounded to the high-voltage board grounding electrode 24 and the mixed contact prevention grounding electrode 22.

  As shown in FIG. 3, in the embodiment, a ground line network including the PV system ground electrode 20, the ground trunk lines 40 and 42, and the ground branch line 9 is provided. First, a plurality of ground trunks 40 and 42 are branched from one PV system ground electrode 20. Further, a plurality of ground branch lines 9 are branched from the ground trunk lines 40 and 42, respectively. Further, the ends of the plurality of ground branch lines 9 are connected to the plurality of solar cell arrays 1a to 1h, respectively.

The thickness of the ground wire 9 will be described. The ground trunk lines 40 and 42 are preferably thicker than the ground branch line 9. The ground trunk line may be a cable having a cross-sectional area of 100 mm ² or more. The ground branch line 9 may be a cable having a cross-sectional area of 60 mm ² or more.

In addition, although not shown in figure, the grounding method of the solar cell panel 2 is as follows. A panel ground wire (not shown) is connected to the solar cell panel 2, and this panel ground wire is connected to the frame 3 or the frame of the adjacent solar cell panel 2. In some cases, grounding between the gantry 3 and the solar cell panel 2 is performed by a mounting bracket instead of the panel ground wire. Panel ground line of the solar cell panel 2 may be a cable wire cross-sectional area of about 2 mm ^2, strand cross-sectional area may be larger cable than 2 mm ^2.

  FIG. 4 is a diagram showing an outline of the photovoltaic power generation system 10 and its grounding method according to the embodiment of the present invention. FIG. 4 shows a simplified grounding structure in the detailed structure of FIG. 3 for convenience of explanation. In FIG. 4, the solar cell arrays 1e to 1h are omitted for simplification of description. Similarly to the description in FIGS. 1 and 2, for convenience, the solar cell array 1a is also referred to as “first solar cell array 1a”, and the solar cell array 1b is also referred to as “second solar cell array 1b”. For convenience, the ground line connected to the first solar cell array 1a is also referred to as "first ground line", and the ground line connected to the second solar cell array 1b is also referred to as "second ground line".

  In light of the above-described “definition of terms in the embodiment”, in the photovoltaic power generation system 10 illustrated in FIG. 4, the ground trunk 40 connected to the PV system ground electrode 20 and the first ground branch 9 a are “first”. It corresponds to “one ground wire”. Further, the second ground branch line 9b corresponds to a “second ground line”. The “first ground branch line” is a ground branch line 9 that connects the first solar cell array 1 a and the ground trunk line 40 among the plurality of ground branch lines 9. The “second ground branch line” is a ground branch line 9 that connects the second solar cell array 1b and the ground trunk line 40 among the plurality of ground branch lines.

  One end of the second ground branch 9b is connected to the second solar cell array 1b, and the other end of the second ground branch 9b is connected to the ground trunk 40. That is, the second ground branch line 9 b is branched from the middle of the ground trunk 40. The solar cell arrays 1e and 1f in FIG. 3 are also connected to the PV system ground electrode 20 via the ground branch line 9 branched from the ground trunk line 40, similarly to the second solar cell array 1b. Similarly, the ground trunk line 42 is connected to the solar cell arrays 1c, 1d, 1g, and 1h via a plurality of ground branch lines 9. This is a so-called tree-type trunk line system. The grounding structure of FIG. 4 is similar to the grounding structure described with reference to FIG. 2 in that the grounding wires 9, 40 and 42 have a branch structure.

  Next, a modification of the embodiment will be described. 5-8 is a figure which shows the modification of the solar power generation system 10 concerning Embodiment of this invention, and its grounding method. 5 to 8 show various modifications of the grounding wire structure in the above-described photovoltaic power generation system 10.

  As shown in FIG. 5, the ground trunk line 44 may be connected to the PV system ground electrode 20, and the end of the ground trunk line 44 may be terminated in a state where the solar cell arrays 1 a to 1 h are not connected. The structure of FIG. 5 is the same type trunk system as FIG. 4 described above. However, in FIG. 4, the PV system ground electrode 20 and the plurality of ground trunk lines 40 and 42 are directly connected to each other. On the other hand, in FIG. 5, the PV system ground electrode 20 and one ground trunk line 44 are connected via the ground wire 9.

  In light of the above-mentioned “definition of terms in the embodiment”, in the photovoltaic power generation system 10 of FIG. 5, two first ground branch lines interposed between the PV system ground electrode 20 and the first solar cell array 1 a. The 9a and the ground trunk line 44 correspond to the “first ground line”. Further, the second ground branch line 9 b branched from the middle of the ground trunk line 44 and connected to the second solar cell array 1 b corresponds to a “second ground line”. In the case of FIG. 5, the second ground line is connected in the middle of the first ground line.

  As shown in FIG. 6, the PV system ground electrode 20 may be connected to one end of one ground trunk 46 and the first solar cell array 1 a may be connected to the other end of the ground trunk 46. Solar cell arrays 1 b and 1 c are connected to the ground trunk line 46 via a plurality of ground branch lines 9. This is a so-called bus type trunk line system. In light of the above-described “definition of terms in the embodiment”, in the photovoltaic power generation system 10 of FIG. 6, the ground main line 46 that connects the PV system ground electrode 20 and the first solar cell array 1 a is “first It corresponds to “Grounding wire”. Further, the second ground branch line 9b branched from the middle of the ground trunk line 46 and connected to the second solar cell array 1b corresponds to a “second ground line”. In the case of FIG. 6, the second ground line is connected in the middle of the first ground line.

  As shown in FIG. 7, the ground trunk line 48 may have an annular shape in which one end and the other end are connected to the PV system ground electrode 20. Either an annular shape or a polygonal shape may be used. Further, as shown in FIG. 8, the ground trunk line 48 is an annular shape in which one end and the other end are connected to each other, and the ground trunk line 48 and the PV system ground electrode 20 may be connected via the ground line 9. One or more ground branch lines 9 are branched from the annular ground trunk line 48, and solar cell arrays 1 a to 1 f are connected to the ends of the ground branch lines 9. This is a ring type trunk line system.

  In light of the above-mentioned “definition of terms in the embodiment”, in the photovoltaic power generation system 10 of FIGS. 7 and 8, at least one interposed between the PV system ground electrode 20 and the first solar cell array 1a. The first ground branch line 9a and the ground trunk line 48 correspond to the “first ground line”. Furthermore, the second ground branch line 9b branched from the middle of the ground trunk line 48 and connected to the second solar cell array 1b corresponds to a “second ground line”. In the case of FIG. 7 and FIG. 8, the second ground line is connected in the middle of the first ground line.

In the embodiment shown in FIGS. 3 to 8 and the modification thereof, the ground trunk lines 40 to 48 are preferably thicker than the ground branch line 9. Specifically, the ground trunk lines 40 to 48 may be cables having a wire cross-sectional area of 100 mm ² or more in thickness. Further, the ground branch line 9 may be a cable having a wire cross-sectional area of 60 mm ² or more in thickness. However, as another modification, the ground trunk lines 40 to 48 and the ground branch line 9 may be cables having the same thickness, or the ground trunk lines 40 to 48 may be narrower than the ground branch line 9.

Moreover, you may select the thickness of the grounding wires 9, 40, and 42 concerning the photovoltaic power generation system 10 of FIGS. 3-8 similarly to having demonstrated with reference to FIG. 1 and FIG. That is, any of the ground wires 9, 40, 42 may be a cable having a strand cross-sectional area thicker than 2 mm ^{2, and} each of the ground wires 9, 40, 42 may be a thick wire having a strand cross-sectional area of 2 mm ² or more. A cable having a length may be used. Strand cross-sectional area as the ground line 9,40,42 may also be used for cable 3.8 mm ² 100 mm ^2.

  In addition, embodiment mentioned above and its modification may be provided as "the grounding method of a solar power generation system." The ground wire of the conventional solar power generation system prepared in advance may be removed, and the ground wires 9, 40, and 42 may be attached as in the connection forms shown in FIGS. By doing in this way, the grounding method concerning an embodiment can be used also to an existing photovoltaic power generation system.

DESCRIPTION OF SYMBOLS 1a Solar cell array (1st solar cell array), 1b Solar cell array (2nd solar cell array), 1c-1h Solar cell array, 2 Solar cell panel, 3 mounts, 4 Connection box, 9 Ground line (ground branch line) , 9a First ground line (first ground branch line), 9b Second ground line (second ground branch line), 10, 100 Photovoltaic power generation system, 20 PV system ground electrode, 22 Incompatibility ground electrode, 24 High voltage panel ground electrode , 30 Current collection box, 32 Power conditioner, 33 Transformer, 34 High voltage board, 38 Pull-in pole, 39 Power transmission line, 40, 42, 44, 46, 48 Ground line (grounded main line), Cf Air floating capacity, Ix noise transmission Route

The photovoltaic power generation system according to the first invention of the present application is
A first solar cell array that outputs DC power ;
A first junction box for receiving DC power from the first solar cell array;
A second solar cell array that outputs DC power ;
A second junction box for receiving DC power from the second solar cell array;
A current collection box for collecting the DC power supplied from the first solar cell array through the first connection box and the DC power supplied from the second solar cell array through the second connection box ;
The DC power collector with collector boxes are inputted, comprising a DC-AC converting inverter circuit for converting DC power inputted into AC power, a power conversion device and connected to the earth electrode,
A first ground line connecting the first solar cell array and the ground electrode;
A second ground wire having one end connected to the second solar cell array and the other end connected to the ground electrode or the first ground wire;
Is provided.

The photovoltaic power generation system according to the second invention of the present application is
A plurality of solar cell arrays each outputting DC power ;
A plurality of junction boxes provided in each of the plurality of solar cell arrays;
A current collection box for collecting DC power supplied through the plurality of connection boxes;
The DC power collector with collector boxes are inputted, comprising a DC-AC converting inverter circuit for converting DC power inputted into AC power, a power conversion device and connected to the earth electrode,
Each of the plurality of solar cell arrays, without interposing another solar cell array, a ground wire group that is directly connected to one ground electrode with a plurality of ground wires,
Is provided.

The grounding method of the photovoltaic power generation system according to the third invention of the present application is as follows:
A first solar cell array having a plurality of first solar cells, a second solar cell array having a plurality of second solar cells, and DC power supplied from the first solar cell and the second solar cell are collected. A photovoltaic power generation comprising: a current collection box for power collection; and a power conversion device including a DC AC conversion inverter circuit that receives DC power collected by the current collection box and converts the input DC power to AC power Prepare the system,
Connect the grounding electrode and the power converter ,
Connecting the grounding electrode and the first solar cell array with a first grounding wire;
One end of the second ground line is connected to the second solar cell array, and the other end of the second ground line is connected to the ground electrode or the first ground line.

Claims (7)

A first solar cell array;
A second solar cell array;
A power conditioner that converts DC power supplied from the first solar cell array and the second solar cell array into AC power and is connected to a ground electrode;
A first ground line connecting the first solar cell array and the ground electrode;
A second ground wire having one end connected to the second solar cell array and the other end connected to the ground electrode or the first ground wire;
A solar power generation system comprising: The first ground wire is
A ground trunk connected to the ground electrode;
A first ground branch line connecting the first solar cell array and the ground trunk line;
Including
The photovoltaic power generation system according to claim 1, wherein the second ground line is a second ground branch line connected to the ground trunk line.   The photovoltaic power generation system according to claim 2, wherein the ground trunk line is thicker than the first ground branch line and the second ground branch line. The ground trunk is a cable having a cross-sectional area of 100 mm ² or more,
The photovoltaic power generation system according to claim 3, wherein the first ground branch line and the second ground branch line are cables having a wire cross-sectional area of 60 mm ² or more in thickness. ^2. The photovoltaic power generation system according to claim 1, wherein each of the first ground wire and the second ground wire is a cable having a wire cross-sectional area of 3.8 mm ² or more. A plurality of solar cell arrays;
A power conditioner that converts DC power supplied from the plurality of solar cell arrays into AC power and is connected to a ground electrode;
Each of the plurality of solar cell arrays, without interposing another solar cell array, a ground wire group that is directly connected to one ground electrode with a plurality of ground wires,
A solar power generation system comprising: DC power supplied from a first solar cell array having a plurality of first solar cells, a second solar cell array having a plurality of second solar cells, and the first solar cell and the second solar cell is exchanged. Preparing a solar power generation system comprising a power conditioner for converting to electric power,
Connect the grounding electrode and the inverter.
Connecting the grounding electrode and the first solar cell array with a first grounding wire;
A grounding method for a photovoltaic power generation system, wherein one end of a second ground line is connected to the second solar cell array, and the other end of the second ground line is connected to the ground electrode or the first ground line.

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