Junction box and solar panel

Abstract

The objective is to provide a junction box and solar cell device that can facilitate the dissipation of heat generated by bypass diodes. [Solution] The junction box and solar cell device of the embodiment form a first wiring space for arranging a first wiring extending from a first solar cell and a second wiring space for arranging a second wiring extending from a second solar cell, as a pair of adjacent spaces separated by a partition wall within the box body of the junction box. The second wiring space has a diode for connecting the second wiring. The diode is provided in a state in contact with the partition wall.

Description

Technical Field

[0001] The present invention relates to a junction box and a solar cell device.

Background Art

[0002] In recent years, tandem solar cells in which Cu2O cells are arranged on silicon cells have been developed. The tandem solar cells extract electric power from each cell and output it to the outside through a junction box. The Cu2O cell has a relatively large voltage, and a plurality of Cu2O cells can be connected in parallel. On the other hand, the silicon cell has a relatively small voltage, and generally a plurality of silicon cells are connected in series. A solar cell in which a plurality of cells are connected in series has a bypass line as a current bypass circuit. Since the bypass diode provided in the bypass line generates heat due to current, a structure that is easy to dissipate heat is desired.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a junction box and a solar cell device that can easily dissipate the heat generated by the bypass diode.

Means for Solving the Problems

[0005] The junction box and solar cell apparatus of the embodiment include, within the box body of the junction box, a first wiring space for arranging the first wiring extending from the first solar cell and a second wiring space for arranging the second wiring extending from the second solar cell, which are adjacent spaces separated by a partition wall. The second wiring space has a diode for connecting the second wiring. The diode is provided in a state in contact with the partition wall. [Effects of the Invention]

[0006] According to the junction box and solar cell device of this embodiment, the heat generated by the bypass diode can be easily dissipated. [Brief explanation of the drawing]

[0007] [Figure 1] An explanatory diagram showing the main parts of a solar cell device in an embodiment of the present invention. [Figure 2] This diagram illustrates the wiring of the top module of the tandem-type solar cell in the above-mentioned solar cell system. [Figure 3] This diagram illustrates the wiring of the bottom module of the tandem solar cell in the above-mentioned solar cell system. [Figure 4] A cross-sectional view showing a first example of a junction box for the above-mentioned solar cell system. [Figure 5] A cross-sectional view showing a second example of a junction box for the above-mentioned solar cell system. [Figure 6] A perspective view showing a third example of a junction box for the above-mentioned solar cell system. [Figure 7] A perspective view showing a first example of the relative arrangement between the junction box and the solar panel. [Figure 8] A perspective view showing a second example of the relative arrangement between the junction box and the solar panel. [Modes for carrying out the invention]

[0008] The solar cell of the embodiment will be described below with reference to the drawings. In the following description, components having the same or similar functions will be denoted by the same reference numerals. Duplication of these components may be omitted.

[0009] Figure 1 is an explanatory diagram including a partial cross-section showing the main parts of the solar cell apparatus 1A of the embodiment. Figure 1 includes a portion of the cross-section of the tandem solar cell 1 of the solar cell apparatus 1A. As shown in Figure 1, the solar cell device 1A includes a tandem solar cell 1 and a junction box (terminal box) 50 for connecting the wiring 21 and 22 extending from the tandem solar cell 1. The tandem solar cell 1 is formed, for example, in the shape of a rectangular flat plate. Hereinafter, the thickness direction of the tandem solar cell 1 may be referred to as the "thickness direction Z" or "Z direction".

[0010] Here, referring to Figures 2 and 3 together, we define the X and Y directions perpendicular to the thickness direction Z. The X direction is the direction along one side of the plan view shape of the tandem solar cell 1 (the top and bottom sides in Figures 2 and 3) (the left and right directions in Figures 2 and 3), and the Y direction is the direction along the other side of the plan view shape of the tandem solar cell 1 that is perpendicular to the aforementioned side (the left and right sides in Figures 2 and 3) (the up and down directions in Figures 2 and 3). The +X side and -X side of the X direction indicate opposite sides to each other; for example, the +X side indicates the right side in Figures 2 and 3, and the -X side indicates the left side in Figures 2 and 3. The +Y side and -Y side of the Y direction indicate opposite sides to each other; for example, the +Y side indicates the top side in Figures 2 and 3, and the -Y side indicates the bottom side in Figures 2 and 3. The +Z side and -Z side of the Z direction indicate opposite sides to each other; the +Z side indicates the "front side," and the -Z side indicates the "back side."

[0011] Referring to Figure 1, the tandem solar cell 1 comprises a bottom module 10 equipped with a solar cell (second solar cell) 12 constituting a back cell, a top module 40 equipped with a solar cell (first solar cell) 42 positioned on the front side of the bottom module 10 and constituting a front cell, and a package 8 housing the bottom module 10 and the top module 40. In the figure, reference numerals 8a and 8b indicate the surface layer and back layer, made of glass or film, that form the front and back surfaces, respectively, in the thickness direction of the package 8. The bottom module 10 and the top module 40 are sandwiched between the surface layer 8a and the back layer 8b via sealing layers 9a and 9b on the front and back sides, respectively. The bottom module 10 and the top module 40 are joined to each other via an intermediate layer 9c. The sealing layers 9a and 9b and the intermediate layer 9c are integrally formed from the same material as the outer peripheral layer 9d that covers the outer periphery of the tandem solar cell 1. The intermediate layer 9c may be an adhesive layer made of an adhesive material independent of the outer peripheral layer 9d.

[0012] The first wiring 21 extending from the top module 40 connects multiple first solar cells 42 that make up the top module 40 in parallel (see Figure 2). The second wiring 22 extending from the bottom module 10 connects multiple second solar cells 12 constituting the bottom module 10 in series (see Figure 3). The second wiring 22 is provided with a bypass path 24 and a bypass diode 25, which will be described later.

[0013] Figure 2 is a plan view showing the wiring of the top module 40 in the embodiment. As shown in Figure 2, the top module 40 comprises multiple top solar panels 41. Each top solar panel 41 is arranged along a common XY plane. Each top solar panel 41 comprises multiple first solar cells 42. In each top solar panel 41, the multiple first solar cells 42 are connected in parallel by first wiring 21.

[0014] Referring also to FIG. 1, for example, each first solar cell 42 of the top module 40 is a transmissive solar cell. For example, each first solar cell 42 has a light absorption layer with a larger bandgap than the light absorption layer of the second solar cell 12 of the bottom module 10. For example, the light absorption layer of each first solar cell 42 contains Cu2O. For example, on the front side of the glass substrate of each first solar cell 42, a p electrode, a chemical layer, and an n electrode are laminated, and each top solar cell panel 41 is arranged with the light receiving surface facing the front side. That is, the normal direction of the light receiving surface of each top solar cell panel 41 is along the thickness direction Z. Each top solar cell panel 41 is formed in a rectangular shape where a pair of sides extends in the X direction and the remaining pair of sides extends in the Y direction in plan view. In the present embodiment, each top solar cell panel 41 forms a rectangular shape along the outer peripheral sides in the X direction and the Y direction in plan view.

[0015] Referring to FIG. 2, the top module 40 forms a plurality of top panel rows 41R extending in the X direction. Each top panel row 41R is formed by connecting a plurality of first solar cells 42 arranged in parallel in the X direction. The plurality of top panel rows 41R are arranged side by side in the Y direction with an interval. In the top module 40, the plurality of first solar cells 42 are arranged in a grid pattern aligned in the X direction and the Y direction. The overall outer shape of the plurality of first solar cells 42 arranged in a grid pattern is formed in a rectangular shape along the outer peripheral sides in the X direction and the Y direction.

[0016] The plurality of first solar cells 42 of the top module 40 are arranged so as to overlap the plurality of second solar cells 12 of the bottom module 10 in plan view. The tandem solar cell 1 is provided with the plurality of first solar cells 42 of the top module 40 and the plurality of second solar cells 12 of the bottom module 10.

[0017] The top module 40 includes a bus bar 31, a branch bus bar 31a, and a connector 18. The bus bar 31, the branch bus bar 31a, and the connector 18 are included in the first wiring 21. The bus bar 31 is provided at the center in the X direction of the top module 40 and extends in the Y direction. The branch bus bar 31a is located, for example, on the +Y side of each top panel row 41R and extends in the X direction. These plurality of branch bus bars 31a extend from the bus bar 31 at the center in the X direction to both sides in the X direction respectively. Each branch bus bar 31a is connected to each first solar cell 42 of the top panel row 41R located on its -Y side via the connector 18.

[0018] FIG. 3 is a plan view showing the wiring of the bottom module 10 of the embodiment. As shown in FIG. 3, the bottom module 10 includes a plurality of bottom solar cell panels 11. Each bottom solar cell panel 11 is arranged along a common XY plane. Each bottom solar cell panel 11 includes at least one solar cell group 12A. In each bottom solar cell panel 11, a specified number of second solar cells 12 constituting the solar cell group 12A are connected in series by the second wiring 22.

[0019] Referring also to FIG. 1, for example, each second solar cell 12 of the bottom module 10 is a silicon-based solar cell using Si for the light absorption layer. For example, each second solar cell 12 is a back contact type solar cell having an n-type electrode and a p-type electrode on the back side of the light absorption layer. Each bottom solar cell panel 11 is arranged with the light receiving surface facing the front side. That is, the normal direction of the light receiving surface of each bottom solar cell panel 11 is along the thickness direction Z. Each bottom solar cell panel 11 is formed in a rectangular shape in plan view with a pair of sides extending in the X direction and the remaining pair of sides extending in the Y direction. In the present embodiment, each bottom solar cell panel 11 is formed in a rectangular shape along the outer peripheral sides in the X direction and the Y direction in plan view.

[0020] Referring to Figure 3, the bottom module 10 forms multiple bottom panel rows 11R extending in the X direction. Each bottom panel row 11R is formed by connecting multiple second solar cells 12 aligned in the X direction in series. The multiple bottom panel rows 11R are spaced apart and aligned in the Y direction. In the bottom module 10, the multiple second solar cells 12 are arranged in a grid pattern aligned in the X and Y directions. The overall shape of each solar cell group 12A is formed in a rectangular shape with its outer periphery aligned in the X and Y directions.

[0021] The bottom panel row 11R includes a negative terminal electrically connected to the n-type electrode and a positive terminal electrically connected to the p-type electrode (neither of which are shown). For example, the negative terminals are provided in order from the +Y side to the -Y side, at the +X side end of each second solar cell 12 in odd-numbered bottom panel rows 11R, and at the -X side end of each second solar cell 12 in even-numbered bottom panel rows 11R.

[0022] The bottom module 10 includes an interconnector 16, a panel row end connector 17, a busbar 35, and a bypass diode 25. The interconnector 16, the panel row end connector 17, the busbar 35, and the bypass diode 25 are included in the second wiring 22. The interconnector 16 connects two adjacent pairs of second solar cells 12 in series within the bottom panel row 11R. The interconnector 16 connects the negative terminal of one of the adjacent pairs of second solar cells 12 to the positive terminal of the other second solar cell 12. The panel row end connector 17 connects the negative terminal and the positive terminal at the X-direction ends of a pair of top and bottom panel rows 11R that are arranged vertically.

[0023] The busbar 35 is located in the center of the bottom module 10 in the X direction and extends in the Y direction. The busbar 35 is positioned between the solar cell groups 12A arranged on both sides in the X direction. The busbar 35 is connected to the negative or positive terminal, which is the electrical end of each solar cell group 12A. The busbar 35 includes a first connection path that connects multiple solar cell groups 12A in series and a second connection path that connects multiple solar cell groups 12A in parallel (neither of which are shown). The second connection path includes a bypass path 24 that bypasses one or more solar cell groups 12A. A bypass diode 25 is provided in the bypass path 24. The bypass diode 25 is located inside the junction box 50.

[0024] Figure 4 is an explanatory diagram including a partial cross-section showing a first example of a junction box 50 of an embodiment. As shown in Figure 4, the junction box 50 comprises an outer casing 51 having a rectangular parallelepiped shape, and a partition wall 52 that divides the internal space of the outer casing 51 in a first direction (up and down direction in the figure, arrow H direction). Each component of the junction box 50 is formed of insulating resin, at least on its outer surface. Inside the junction box 50, adjacent first wiring space K1 and second wiring space K2 are formed via the partition wall 52.

[0025] In the junction box 50, the first wiring space K1, located on one side in the first direction (+H side), holds the intermediate portion of the first wiring 21 extending from the top module 40 to the outside (for example, the battery side). The intermediate portion of the first wiring 21 is divided to form terminals on the top module 40 side and the outside side. These pair of terminals are fixed to a terminal block (not shown) within the first wiring space K1.

[0026] In the junction box 50, the intermediate portion of the second wiring 22, which extends from the bottom module 10 to the outside (e.g., the battery side), is inserted into and held in the second wiring space K2 located on the other side (-H side) of the first direction. The intermediate portion of the second wiring 22 is divided to form terminals on the bottom module 10 side and the outside side. These pair of terminals are fixed to a terminal block (not shown) including a bypass diode 25 within the second wiring space K2.

[0027] The bypass diode 25 generates heat due to the current. Therefore, even inside the enclosed junction box 50, a configuration is required to improve the heat dissipation of the bypass diode 25. In this embodiment, the bypass diode 25 is provided in a state where it is constantly in contact with the partition wall 52. The junction box 50 of the embodiment has a contact structure 55 for bringing the bypass diode 25 into contact with the partition wall 52. For example, the contact structure 55 may be a structure in which a screw member is attached to the -H side wall (lower wall) of the outer casing, this screw member is extended toward the partition wall 52, and the bypass diode 25 is sandwiched and fixed between the screw member and the partition wall 52. For example, the contact structure 55 may be a structure in which an elastic member such as a coil spring is provided between the lower wall and the partition wall 52, and the biasing force of this elastic member biases the bypass diode 25 toward the partition wall 52, pressing the bypass diode 25 against the partition wall 52 and holding it. For example, the contact structure 55 may be a combination of the screw member and the elastic member. The lower wall side of the junction box 50 may be detachable.

[0028] Since the bypass diode 25 remains in contact with the partition wall 52, the heat generated by the bypass diode 25 is transferred to the first wiring 21 in the first wiring space K1 via the partition wall 52. This improves the heat dissipation of the bypass diode 25. The junction box 50 of this embodiment includes a holding structure 57 that holds the first wiring 21, which is placed in the first wiring space K1, in contact with the partition wall 52. The holding structure 57 is, for example, a cable tie or tape, and holds the first wiring 21 in contact with the partition wall 52. This makes it easier for the heat generated by the bypass diode 25 to be transferred to the first wiring 21, thereby improving the heat dissipation of the bypass diode 25. The holding structure 57 may be a mechanism such as the contact structure 55.

[0029] Figure 5 is an explanatory diagram including a partial cross-section showing a second example of the junction box 50 of the embodiment. As shown in Figure 5, the partition wall 52 of the junction box 50 may be configured to be separated from the outer casing 51. In the second example, the partition wall 52 is displaceable toward the +H side wall (upper wall) together with the bypass diode 25. The bypass diode 25 maintains contact with the partition wall 52. The first wiring 21 in the first wiring space K1 is sandwiched between the upper wall and the partition wall 52 and is in close contact with the partition wall 52. Since the bypass diode 25 and the first wiring 21 maintain contact with the partition wall 52, the heat generated by the bypass diode 25 is more easily transferred to the first wiring 21, and the heat dissipation of the bypass diode 25 can be further improved.

[0030] Figure 6 is an explanatory diagram including a partial cross-section showing a third example of the junction box 50 of the embodiment. In Figure 6, the outer casing 51 of the junction box 50 is omitted from the illustration. As shown in Figure 6, a highly heat-conductive metal plate (heat-conducting member) 59 may be attached to the surface (upper surface) of the partition wall 52 on the first wiring space K1 side in the area where the first wiring 21 is in contact. The metal plate 59 has a size equivalent to that of the bypass diode 25 in a plan view, for example, when viewed from the H direction. This allows the metal plate 59 itself to act as a heat-receiving member, making it easier to dissipate the heat from the bypass diode 25 to the first wiring space K1 side. Furthermore, by bringing the first wiring 21 into contact with the metal plate 59, the heat from the bypass diode 25 is more easily transferred to the first wiring 21, thereby improving the heat dissipation performance of the bypass diode 25. Furthermore, a metal plate 59 may also be attached between the bypass diode 25 and the partition wall 52. In this case, the metal plate 59 in contact with the bypass diode 25 has a larger surface area than the contact surface with the bypass diode 25, and the metal plate 59 in contact with the first wiring 21 has an area of ​​about the same size as the metal plate 59 in contact with the bypass diode 25, thereby enabling more efficient heat transfer.

[0031] Figure 7 is a perspective view showing a first example of the relative arrangement of the metal plate 59, bypass diode 25, partition wall 52, etc. inside the junction box 50 and the solar panel (tandem solar cell 1). In Figure 7, the outer casing 51 of the junction box 50 is omitted from the illustration. As shown in Figure 7, the junction box 50 may be positioned with its thickness direction H aligned with the thickness direction Z of the tandem solar cell 1.

[0032] Figure 8 is a perspective view showing a first example of the relative arrangement of the metal plate 59, bypass diode 25, partition wall 52, etc. inside the junction box 50 and the solar panel (tandem solar cell 1). In Figure 8, the outer casing 51 of the junction box 50 is omitted from the illustration. As shown in Figure 8, the junction box 50 may be positioned with its thickness direction H aligned with the plane direction (X direction or Y direction) of the tandem solar cell 1. As shown in these examples, the arrangement of the bypass diode 25, partition wall 52, first wiring 21, and second wiring 22 is not limited. They can be arranged appropriately depending on the required surface size, thickness, etc., for the solar cell device 1A.

[0033] As described above, the junction box 50 in the above embodiment has a box body (outer casing 51) with a first wiring space K1 for arranging the first wiring 21 extending from the first solar cell (top module 40) and a second wiring space K2 for arranging the second wiring 22 extending from the second solar cell (bottom module 10) as a pair of adjacent spaces separated by a partition wall 52. The second wiring space K2 is provided with a bypass diode 25 for connecting the second wiring 22, and the bypass diode 25 is provided in contact with the partition wall 52.

[0034] Furthermore, the solar cell device 1A of the above embodiment includes a tandem solar cell 1 and a junction box 50 for connecting wiring extending from the tandem solar cell 1. The junction box 50 has a box body (outer casing 51) that forms a pair of adjacent spaces separated by a partition wall 52: a first wiring space K1 for arranging a first wiring 21 extending from a first solar cell (top module 40), and a second wiring space K2 for arranging a second wiring 22 extending from a second solar cell (bottom module 10). The second wiring space K2 is provided with a bypass diode 25 for connecting the second wiring 22, and the bypass diode 25 is provided in contact with the partition wall 52.

[0035] In this configuration, a first wiring space K1 and a second wiring space K2 are formed adjacent to each other within the junction box 50 via a partition wall 52, and a bypass diode 25 connecting the second wiring 22 is provided in the second wiring space K2 in contact with the partition wall 52. As a result, the heat generated by the current in the second wiring 22 in the bypass diode 25 is easily transferred to the first wiring 21 in the first wiring space K1 via the partition wall 52. Therefore, the heat dissipation of the bypass diode 25 can be improved.

[0036] Furthermore, the junction box 50 is equipped with a contact structure 55 that brings the bypass diode 25 into contact with the partition wall 52. This configuration includes a contact structure 55 that brings the bypass diode 25 into contact with the partition wall 52, thereby ensuring that the bypass diode 25 is reliably in contact with the partition wall 52. This reliably improves the heat dissipation of the bypass diode 25.

[0037] Furthermore, the junction box 50 includes a holding structure 57 that holds the first wiring 21, which is placed in the first wiring space K1, in contact with the partition wall 52. With this configuration, by providing a holding structure 57 that brings the first wiring 21 in the first wiring space K1 into contact with the partition wall 52, the heat generated by the bypass diode 25 is more easily transferred from the partition wall 52 to the first wiring 21. Therefore, the heat dissipation performance of the bypass diode 25 can be further improved.

[0038] Furthermore, in the solar cell device 1A described above, the first wiring 21 is connected to a plurality of first solar cells 42 in the first solar cell (top module 40), and the second wiring 22 connects a plurality of second solar cells 12 in the second solar cell (bottom module 10) in series, and is connected to the series-connected solar cell group 12A via the bypass diode 25. In this configuration, the first wiring 21 and second wiring 22 extending from the solar cells 12 and 42 of each solar cell are placed in the first wiring space K1 and the second wiring space K2, respectively, which are partitioned by a partition wall 52 in the junction box 50. The bypass diode 25 placed in the second wiring space K2 is installed in contact with the partition wall 52. This makes it easier for the heat generated by the bypass diode 25 to be transferred to the first wiring 21 in the first wiring space K1 via the partition wall 52. As a result, the heat dissipation of the bypass diode 25 can be improved.

[0039] Furthermore, in the solar cell device 1A described above, the first wiring 21 connects a plurality of the first solar cells 42 in parallel. In this configuration, the length of the first wiring 21, which is placed in the first wiring space K1, is ensured by connecting multiple first solar cells 42 in parallel. This makes it easier for the heat generated by the bypass diode 25 to be transferred to the first wiring 21, thereby improving the heat dissipation of the bypass diode 25.

[0040] According to at least one embodiment described above, the junction box 50 has a first wiring space K1 and a second wiring space K2 adjacent to each other within the box body, separated by a partition wall 52. The second wiring space K2 is provided with a bypass diode 25 that connects to the second wiring 22. The bypass diode 25 is installed in contact with the partition wall 52. With this configuration, the heat generated in the bypass diode 25 by the current in the second wiring 22 is easily transferred to the first wiring 21 in the first wiring space K1 via the partition wall 52. This improves the heat dissipation of the bypass diode 25.

[0041] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0042] 1...Tandem-type solar cell (solar cell), 1A...Solar cell device, 10...Bottom module (first solar cell), 12...Second solar cell, 12A...Solar cell group, 21...First wiring, 22...Second wiring, 25...Bypass diode (diode), 40...Top module (second solar cell), 42...First solar cell, 50...Junction box, 51...Outer casing (box body), 52...Partition wall, 55...Contact structure, 57...Holding structure, 59...Metal plate (thermal transfer member), K1...First wiring space, K2...Second wiring space

Claims

1. Within the box body, a first wiring space is formed, separated by a partition wall, for arranging the first wiring extending from the first solar cell, and a second wiring space is formed for arranging the second wiring extending from the second solar cell. The second wiring space is provided with a bypass diode for connecting the second wiring, The bypass diode is installed in a junction box in contact with the partition wall.

2. The junction box according to claim 1, further comprising a contact structure for bringing the bypass diode into contact with the partition wall.

3. The junction box according to claim 1, further comprising a holding structure for holding the first wiring arranged in the first wiring space in contact with the partition wall.

4. The junction box according to any one of claims 1 to 3, wherein at least one of the bypass diode and the first wiring is provided in contact with the partition wall via a heat conductive member.

5. The system comprises a solar cell and a junction box for connecting wiring extending from the solar cell, The junction box has, within its box body, a pair of adjacent spaces separated by a partition wall: a first wiring space for arranging the first wiring extending from the first solar cell, and a second wiring space for arranging the second wiring extending from the second solar cell. The second wiring space is provided with a bypass diode for connecting the second wiring, The aforementioned bypass diode is provided in contact with the partition wall in a solar cell device.

6. The first wiring is connected to a plurality of first solar cells in the first solar cell, The solar cell apparatus according to claim 5, wherein the second wiring connects a plurality of second solar cells in the second solar cell in series and is connected to the group of solar cells connected in series via the bypass diode.

7. The solar cell apparatus according to claim 6, wherein the first wiring connects a plurality of the first solar cells in parallel.

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