Solar battery cell string, solar battery cell string unit, solar battery module, and method for manufacturing solar battery module

Abstract

In this solar battery cell string, a plurality of solar battery cells (20) arranged along a first direction (D1) are electrically connected by inter-cell wiring (32). The inter-cell wiring (32) comprises a first wiring part (31) extending in the first direction (D1), and a second wiring part (32) connected to the first wiring part (31) and extending in a second direction (D2), and is disposed at least between the solar battery cells (20) adjacent to each other in the first direction (D1). The first wiring part (31) is connected to an electrode of the solar battery cell (20). The second wiring part (32) is provided so as to be longer than the length of the solar battery cell (20) in the second direction (D2) and shorter than 1.5 times the length of the solar battery cell (20) in the second direction (D2), and at least one end (321, 322) of the second wiring part in the second direction (D2) extends more than the solar battery cell (20).

Description

Solar cell string, solar cell string unit, solar cell module, and method for manufacturing solar cell module

[0001] The present disclosure relates to a solar cell string, a solar cell string unit including the solar cell string, a solar cell module, and a method for manufacturing the solar cell module.

[0002] Solar cells are used to convert sunlight into electricity using the photovoltaic effect. For example, as shown in FIG. 16 , a solar cell module 90a using approximately rectangular crystalline silicon solar cells (solar cell 91) is widely used. Furthermore, the solar cell module 90a typically has six solar cell strings 93 connected in series. Each solar cell string 93 includes multiple solar cells 91, which are electrically connected in series with wiring. In this type of solar cell module 90a, output wiring 94 extends through a slit (not shown) on the back side, and a terminal box 95 is provided to cover the opening and extract the output of the solar cell module 90a. FIG. 17 shows a schematic configuration example of the terminal box 95.

[0003] In certain usage situations, if a solar cell module is partially shaded, the current value will decrease depending on the shade conditions, but even if just one solar cell is shaded, the solar cell module may completely stop generating power because the solar cells are connected in series. To prevent this, a solar cell module is generally used in which one bypass diode 97 is connected to, for example, two solar cell strings, as shown in Fig. 17 (see, for example, Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2020-098931

[0005] In the conventional solar cell module, if some of the multiple solar cells are shaded by a building or have foreign matter attached to them, they will not receive sunlight and will no longer generate electricity. When this happens, a bypass diode will function, but even if just one solar cell stops generating electricity, two solar cell strings will no longer contribute to power generation. This is fine for solar cell modules installed on rooftops where there is little shadowing. However, solar cell modules installed on mobile objects such as vehicles are frequently shaded. Therefore, if partial shading causes a power loss equivalent to two solar cell strings each time, this will have a significant impact on the overall power generation. Installing a bypass diode for each solar cell to prevent this would result in a complex structure and a significant cost impact.

[0006] The present disclosure has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a solar cell string, a solar cell string unit, a solar cell module, and a method for manufacturing a solar cell module that can reduce the effect of reduced power generation due to partial shading and increase the actual power generation amount.

[0007] The present disclosure provides a solar cell string comprising a plurality of solar cells arranged along a first direction and electrically connected by inter-cell wiring, the inter-cell wiring comprising a first wiring portion extending in the first direction and a second wiring portion connected to the first wiring portion and extending in a second direction intersecting the first direction, the inter-cell wiring being arranged at least between adjacent solar cells in the first direction, the first wiring portion being connected to electrodes of the solar cells, the second wiring portion being longer than the length of the solar cell in the second direction and shorter than 1.5 times the length of the solar cell in the second direction, and at least one end in the second direction extending further in the second direction than the solar cell.

[0008] The present disclosure also provides a solar cell string unit including a plurality of solar cell strings, each of which has a plurality of solar cells arranged along a first direction electrically connected by inter-cell wiring, the inter-cell wiring including a first wiring portion extending in the first direction and a second wiring portion connected to the first wiring portion and extending in a second direction intersecting the first direction, the plurality of solar cell strings being arranged side by side in the second direction, at least one of the plurality of solar cell strings arranged in the second direction being the solar cell string A described in claim 1, and the second wiring portion extending from the solar cell string A being connected to the second wiring portion of another adjacent solar cell string.

[0009] In a solar cell string unit having the above configuration, the solar cell string unit is characterized in that a plurality of the solar cell cells adjacent to each other in the first direction are connected by the inter-cell wiring and electrically connected in series, and a plurality of the solar cell cells adjacent to each other in the second direction are connected by the inter-cell wiring and electrically connected in parallel.

[0010] Furthermore, a solar cell module including the solar cell string unit also falls within the scope of the technical idea of ​​the present disclosure.

[0011] In the solar cell module, the solar cell is a back electrode type solar cell having the electrode on one surface of a semiconductor substrate.

[0012] In the solar cell module, it is preferable that the solar cell includes a first conductivity type cell electrode and a second conductivity type cell electrode as the electrodes, a first collector electrode connected to the first conductivity type cell electrode is provided on one side of the first direction of the semiconductor substrate, and a second collector electrode connected to the second conductivity type cell electrode is provided on the other side of the first direction, and the first wiring portion of the inter-cell wiring is connected to the first collector electrode of one of two solar cell cells adjacent to each other in the first direction and the second collector electrode of the other solar cell.

[0013] In the solar cell module, the inter-cell wiring preferably has an opening at an intersection of the first wiring portion and the second wiring portion.

[0014] In the solar cell module, the solar cells may be double-sided electrode solar cells having, as the electrodes, a front electrode on a light-receiving surface side and a back electrode on a surface opposite to the light-receiving surface. Preferably, the first wiring portion of the inter-cell wiring extending in one direction in the first direction is connected to the front electrode of one of two solar cells adjacent to each other in the first direction, and the first wiring portion extending in the other direction in the first direction is connected to the back electrode of the other solar cell.

[0015] The present disclosure relates to a method for manufacturing a solar cell module having a solar cell string unit including a plurality of solar cell strings, the method including a string fabrication process of arranging a plurality of solar cells having electrodes on a semiconductor substrate along a first direction, and electrically connecting the solar cells adjacent to each other in the first direction in series with inter-cell wiring to fabricate the solar cell string, the inter-cell wiring comprising a first wiring portion extending in the first direction, and a second wiring portion connected to a plurality of the first wiring portions and extending in a second direction intersecting the first direction, the second wiring portion being longer than the length of the solar cell in the second direction, the string fabrication process connecting the first wiring portion to the electrodes of the solar cell, and after the string fabrication process, connecting the second wiring portion extending from the solar cell string to the inter-cell wiring of another solar cell string adjacent to each other in the second direction, to fabricate the solar cell string unit.

[0016] According to the present disclosure, it is possible to stabilize the amount of power generated by a solar cell module.

[0017] 12( a ) is a plan view showing a solar cell string according to embodiment 1 as viewed from the back surface side; FIG. 12( b ) is a plan view showing an electrode structure of solar cells provided in the solar cell string; FIG. 12( c ) is a plan view showing inter-cell wiring in the solar cell string; FIG. 12( a ) is a plan view showing a solar cell module according to embodiment 1 as viewed from the back surface side; FIG. 12( b ) is a plan view showing another example of the solar cell module according to embodiment 4; and FIG. 12( c ) is a plan view showing an example of a conventional solar cell module. 1 is an explanatory diagram showing an example of the configuration of a terminal box of a conventional solar cell module, and FIG. 2 is an explanatory diagram showing a conventional solar cell module constituted by back electrode type solar cells as viewed from the back side.

[0018] Embodiments of the present disclosure will be described with reference to the drawings.

[0019] (Embodiment 1) Fig. 1 is a plan view showing a solar cell string 11 according to embodiment 1. Fig. 2 is a plan view schematically showing an electrode structure on the back surface side of a solar cell 20 provided in the solar cell string 11, and Fig. 3 is a plan view showing inter-cell wiring 30 of the solar cell string 11. Note that Fig. 1 shows the solar cell string 11 as viewed from the back surface side, which is the surface opposite to the light-receiving surface.

[0020] 1 , the solar cell string 11 includes a plurality of solar cells 20, and the plurality of solar cells 20 are electrically connected by inter-cell wiring (interconnectors) 30. The plurality of solar cells 20 are arranged along a predetermined first direction D1.

[0021] The solar cell 20 is a back electrode type (back contact type) solar cell in which an electrode is provided on the back surface opposite to the light receiving surface, which is one surface of the semiconductor substrate 21. For example, as shown in Fig. 2, the solar cell 20 is provided with a first conductivity type (e.g., n-type) cell electrode 231 and a second conductivity type (e.g., p-type) cell electrode 232 as electrodes on the back surface side of the semiconductor substrate 21. Note that in Fig. 2, the first conductivity type cell electrode 231 is shown by a dashed line and the second conductivity type cell electrode 232 is shown by a solid line to make it easy to distinguish between the two electrodes.

[0022] The first conductivity type cell electrodes 231 and the second conductivity type cell electrodes 232 are provided as a number of linear electrodes extending in the same direction (first direction D1, which is the up-and-down direction in FIG. 2 ) on the rear surface of the semiconductor substrate 21. The first conductivity type cell electrodes 231 and the second conductivity type cell electrodes 232 are provided alternately and parallel to each other, and are arranged at a predetermined interval from each other.

[0023] A first collector electrode 241 connected to a plurality of first conductivity type cell electrodes 231 is provided near one edge portion 211 in the first direction D1 of the semiconductor substrate 21 of the solar cell 20. The first collector electrodes 241 are provided at a plurality of locations spaced apart from one another in a direction (second direction D2) along the edge portion 211 of the semiconductor substrate 21. In the illustrated embodiment, three first collector electrodes 241 are provided in the edge portion 211 that is on the upper side of the solar cell 20 in the drawing.

[0024] Three second collector electrodes 242 connected to the plurality of second conductivity type cell electrodes 232 are provided at intervals from one another near the other edge portion 212 in the first direction D1 of the semiconductor substrate 21. The solar cell 20 is connected to the outside via these first collector electrodes 241 and second collector electrodes 242.

[0025] A silicon substrate made of polycrystalline silicon or single-crystalline silicon having n-type or p-type conductivity can be used as the semiconductor substrate 21. The first conductivity type cell electrode 231 and the second conductivity type cell electrode 232 can each be an electrode made of a metal such as silver or copper.

[0026] It is preferable that an anti-reflection structure (not shown) for suppressing light reflection, such as a textured structure, is provided on the light-receiving surface side of the solar cell 20. It is preferable that an anti-reflection film (not shown) having physical properties for suppressing light reflection is provided on the anti-reflection structure on the light-receiving surface side.

[0027] In this case, the anti-reflection film may be, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, an aluminum oxide film, or a laminated film combining these films. A passivation film (interfacial passivation film, not shown) is preferably provided on the back surface of the semiconductor substrate 21. The passivation film may be, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, an aluminum oxide film, or a laminated film combining these films.

[0028] 3 , the inter-cell wiring 30 includes a first wiring portion 31 extending in a first direction D1 and a second wiring portion 32 extending in a second direction D2 so as to intersect with the first wiring portion 31. In the illustrated embodiment, a plurality of first wiring portions 31 are provided in the inter-cell wiring 30. The plurality of first wiring portions 31 are arranged to correspond to the shape of the cell electrodes, and in the illustrated embodiment, are arranged symmetrically with respect to the strip-shaped second wiring portion 32 that is long in the second direction D2.

[0029] In the inter-cell wiring 30 according to the exemplary embodiment, three first wiring portions 31 a extend in one direction in the first direction D1, and three first wiring portions 31 b extend in the other direction in the first direction D1. These first wiring portions 31 a, 31 b are all provided with the same shape. One first wiring portion 31 a and the other first wiring portion 31 b are arranged on the same straight line with the second wiring portion 32 in between, and are arranged to intersect the second wiring portion 32 in a substantially crisscross shape.

[0030] An end portion of the second wiring portion 32 in the second direction D2 is provided in a shape that extends further in the second direction D2 than the first wiring portion 31. An end portion 321 of the second wiring portion 32 extends to one side of the inter-cell wiring 30 in the second direction D2, and an end portion 322 of the second wiring portion 32 extends to the other side of the second direction D2.

[0031] The inter-cell wiring 30 preferably has openings 33 at intersections between the first wiring portions 31a, 31b and the second wiring portion 32. In the illustrated embodiment, the openings 33 are formed at three intersections between the first wiring portion 31 and the second wiring portion 32. Each opening 33 is elongated in the second direction D2 more than the first direction D1 and has a slit-like, rectangular, or rounded, approximately rectangular shape. Note that the shape of the openings 33 is not limited to that shown in FIG. 3 and may be, for example, an elliptical shape elongated in the second direction D2, or any other shape. The openings 33 are arranged at equal intervals along the second wiring portion 32. The inter-cell wiring 30 is preferably made of a conductive metal foil (e.g., copper foil), and the surface of the metal foil is preferably covered with solder or tin plating.

[0032] As shown in Figure 1, in one solar cell string 11, multiple solar cells 20 (for example, five solar cells 20 in Figure 1) are arranged opposite each other so that the second collector electrode 242 of one solar cell 20 adjacent to the first direction D1 and the first collector electrode 241 of the other solar cell 20 are butted against each other.

[0033] The inter-cell wiring 30 is arranged along the peripheral portions extending in the second direction D2 of the plurality of solar cell 20. In the illustrated embodiment, the inter-cell wiring 30 is arranged between the solar cell 20 adjacent to each other in the first direction D1 and on the peripheral portions of the solar cell 20 at both ends in the first direction D1. The plurality of first wiring portions 31 extending from the inter-cell wiring 30 in the first direction D1 are connected to the electrodes (collecting electrodes) of the solar cell 20, and the solar cell 20 adjacent to each other in the first direction D1 are connected in series. In this way, even if thermal stress due to temperature change acts on the inter-cell wiring 30 between adjacent solar cell 20, the openings 33 can prevent stress concentration, thereby making it possible to suppress damage to the inter-cell wiring 30.

[0034] 1 , the first wiring portions 31 a of the inter-cell wiring 30 are connected to the second collector electrodes 242, and the first wiring portions 31 b are connected to the first collector electrodes 241. To connect the inter-cell wiring 30 to the electrodes of the solar cell 20, a conductive adhesive such as solder, a conductive solder resin, or a conductive paste can be used.

[0035] As a result, the solar cell string 11 is configured to include a plurality of solar cell 20 connected in series, with the upper end portion in Fig. 1 being the positive pole and the lower end portion in the figure being the negative pole. Note that the solar cell cells 20 that make up the solar cell string 11 are not limited to those illustrated in the example, and may be solar cell cells having the same shape and the same area.

[0036] In the solar cell string 11, the second wiring portion 32 of the inter-cell wiring 30 is in a strip shape that is longer than the length in the second direction D2 of the solar cell 20. In the embodiment shown in Fig. 1 , the length L22 of the second wiring portion 32 in the second direction D2 is longer than the length L21 of the solar cell 20 in the second direction D2. Ends 321, 322 of the second wiring portion 32 are provided to extend outward beyond the peripheral portion of the solar cell 20 in the second direction D2.

[0037] As described above, the length L22 of the second wiring portion 32 in the second direction D2 is set to a length such that both ends (321, 322) of the second wiring portion 32 protrude outward in the second direction D2 beyond the peripheral portions of the solar cell 20. In order for both ends of adjacent second wiring portions 32 to be in continuous contact with each other, the length L22 of the second wiring portion 32 in the second direction D2 is preferably longer than 1.05 times the length L21 of the solar cell 20 in the second direction D2, and is preferably at least longer than the length L21 of the solar cell 20 in the second direction D2. Furthermore, the length L22 of the second wiring portion 32 in the second direction D2 is preferably shorter than 1.5 times the length L21 of the solar cell 20 in the second direction D2, and is more preferably shorter than 1.3 times. If the length L22 of the second wiring portion 32 in the second direction D2 is too long, handling and wiring work will be difficult in the string fabrication process and the process of fabricating the solar cell string unit 100 described below, and the cost of the wiring material will also increase.

[0038] FIG. 4 is a plan view showing the solar cell module 1 according to the first embodiment of the present disclosure as viewed from the back surface side, and FIG. 5 is an explanatory diagram showing one step of a manufacturing method for the solar cell module 1 according to the present disclosure, which includes a plurality of solar cell strings 11.

[0039] 4 does not show resin layers, protective members, etc. that are provided on the solar cell module 1. In addition, in FIG. 5, detailed configurations such as electrodes of the solar cell 20 are not shown, and the solar cell 20 is shown in light grey.

[0040] The solar cell module 1 is configured using the solar cell strings 11 configured as described above. As shown in Fig. 4, the solar cell module 1 includes a solar cell string unit 100 configured by arranging a plurality of solar cell strings 11, each of which is provided long in a first direction D1, in a second direction D2.

[0041] The solar cell string 11 shown in FIG. 1 is fabricated by arranging a plurality of solar cells 20 along a first direction D1 and electrically connecting adjacent solar cells 20 in the first direction D1 in series with inter-cell wiring 30 (string fabrication process). The first wiring portions 31a of the inter-cell wiring 30 are connected to the second collector electrodes 242, and the first wiring portions 31b are connected to the first collector electrodes 241. In the string fabrication process, a plurality of such solar cell strings 11 are prepared in advance. The number of solar cells 20 included in one solar cell string 11 is five, but is not limited to five and can be any predetermined number. The number of solar cell strings 11 is six, but is not limited to six and can be any predetermined number.

[0042] 4 , the solar cell string unit 100 includes a plurality of solar cell strings 11, and the plurality of solar cell strings 11 are electrically connected by inter-cell wiring (interconnectors) 30. The plurality of solar cell strings 11 are arranged along a predetermined second direction D2.

[0043] 5 , the solar cell string 11 fabricated in the string fabrication step has second wiring portions 32 extending in the second direction D2. The solar cell string unit 100 is configured by connecting the second wiring portions 32 extending from the solar cell string 11 to second wiring portions 32 extending from another adjacent solar cell string 11. For example, when fabricating the solar cell string unit 100 using the solar cell string 11, one end 321 of the second wiring portion 32 extending from the solar cell string 11 is connected to the other end 322 of the second wiring portion 32 extending from the other adjacent solar cell string 11 in the second direction D2 so as to overlap with it. Alternatively, the other end 322 may be connected to the one end 321 so as to overlap with it.

[0044] The second wiring portions 32 of both inter-cell wirings 30 can be connected using a conductive adhesive such as solder, a conductive solder resin, or a conductive paste, similar to the connection of the electrodes. As shown in Fig. 4 , in the solar cell string unit 100, a plurality of solar cell strings 11 are arranged side by side in the second direction D2 and connected to each other. As shown in Fig. 5 , adjacent solar cell strings 11 are arranged with the same polarity, so that one side in the first direction D1 is a positive pole and the other side is a negative pole. As shown in Fig. 4 , the solar cell strings 11 are arranged in the second direction D2 so that the peripheral portions of the solar cells 20 that are not provided with the first collector electrode 241 or the second collector electrode 242 abut each other.

[0045] As shown in Fig. 5 , the solar cell string unit 100 can be produced by connecting the ends 321 and 322 of the second wiring portions 32 of a predetermined number of solar cell strings 11. For example, in the example shown in Fig. 4 , a solar cell string unit 100 including 30 solar cell cells 20 arranged adjacently in 6 columns and 5 rows is produced. The solar cell cells 20 arranged adjacently in the first direction D1 are connected in series via the inter-cell wiring 30. Furthermore, the solar cell cells 20 arranged adjacently in the second direction D2 are connected in parallel via the inter-cell wiring 30.

[0046] The solar cell module 1 can be obtained by laminating a sealing resin such as an EVA sheet and a transparent substrate on the light-receiving surface side of the solar cell 20 in the solar cell string unit 100 produced in this manner, and laminating a sealing resin such as an EVA sheet and a back sheet on the back surface side, and then laminating them using thermocompression bonding or the like.

[0047] The solar cell module 1 configured in this manner has a connection structure of both solar cell cells 20 connected in series and solar cell cells 20 connected in parallel. If a solar cell 20 is in a reverse bias state due to the influence of partial shading, the solar cell 20 with a reduced current value is thought to become an electrical resistor. However, because of the series-parallel connection structure, current flows through a parallel connection circuit that bypasses that solar cell 20.

[0048] As a result, if the power generation amount of one cell decreases due to the influence of partial shading, in a solar cell module with a conventional structure, the bypass diode will function and the two solar cell strings including that solar cell will no longer contribute to power generation, but with this structure, the power decrease will be limited to the solar cell that is partially shaded, making it possible to suppress the decrease in power generation amount of the solar cell module 1 and stabilize the power generation amount. Moreover, to manufacture such a solar cell module 1, the same manufacturing process as in the conventional method can be used, in which solar cell strings 11 are first manufactured and then the solar cell strings are connected to each other.

[0049] FIG. 18 is an explanatory diagram showing a back surface side of a conventional back electrode type solar cell module composed of back electrode type solar cells 20. Here, the solar cell string 80 included in the solar cell module 90b has inter-cell wiring 81 whose length in the second direction D2 is shorter than the length in the second direction D2 of the solar cell 20. In a conventional manufacturing process, the inter-cell wiring 81 is first formed by connecting the solar cells 20 in series to form the solar cell string 80, and then the solar cell strings 80 are connected in series with wiring members 98. Therefore, the polarities of adjacent solar cell strings 80 (series connection directions) are opposite to each other. Furthermore, the wiring members 98 and output wiring 99 are insulated by an insulating film. The output wiring 99 is wiring for extracting the output of the solar cell module 90b.

[0050] In contrast, the solar cell module 1 according to this embodiment differs from conventional solar cell modules in that it is only necessary to connect the second wiring portions 32 of adjacent inter-cell wirings 30 together while aligning the polarity direction (series connection direction) of the solar cell strings 11, which makes it easy to work with and align the positions, and allows for simple and accurate manufacturing.

[0051] In the solar cell string 11, the second wiring portion 32 of the inter-cell wiring 30 is strip-shaped and longer than the length in the second direction D2 of the solar cell 20, but is provided with a length shorter than 1.5 times the length in the second direction D2 of the solar cell 20. The length of the second wiring portion 32 in the second direction D2 is preferably a length that allows connection to the inter-cell wiring of another adjacent solar cell string. The length of the second wiring portion 32 in the second direction D2 is preferably a length that does not reach, for example, the first wiring portion of the inter-cell wiring of another adjacent solar cell string. The second wiring portion 32 is preferably longer than the length in the second direction D2 of the solar cell 20, but shorter than the combined length in the second direction D2 of two adjacent solar cell cells 20 aligned in the second direction D2.

[0052] As shown in the inter-cell wiring 30 of the solar cell string 11 according to this embodiment, when a plurality of first wiring portions 31 are provided on one side and the other side of the first direction D1, it is preferable that one end of the second wiring portion 32 of the inter-cell wiring 30 protrudes in the second direction D2 beyond the edge portion of the solar cell 20, and that the protruding length is shorter than the spacing between the plurality of first wiring portions 31. It is also preferable that the protruding length of the second wiring portion 32 in the second direction D2 is shorter than the spacing between the plurality of solar cell 20 arranged in the first direction D1.

[0053] Second Embodiment Fig. 6 is a plan view showing a solar cell string 11a according to a second embodiment of the present disclosure as viewed from the back surface side. Fig. 7 is a plan view showing inter-cell wiring 30a that constitutes the solar cell string 11a.

[0054] The solar cell string provided in the solar cell module 1 is not limited to that shown in the first embodiment, and can be configured in various forms. Furthermore, the solar cell 20 may be the same as that shown in Fig. 2, or may have a different configuration.

[0055] For example, a solar cell string 11a according to the embodiment shown in Fig. 6 is characterized by the configuration of inter-cell wiring 30a that connects solar cells 20 to each other, and other basic configurations can be common to those of embodiment 1. In the following description, redundant description of the configuration common to embodiment 1 will be omitted.

[0056] In the solar cell string 11a, only one end 324 of the second wiring portion 32 of the inter-cell wiring 30a extends long in the second direction D2 of the solar cell 20. As shown in Fig. 7 , the second wiring portion 32 of the inter-cell wiring 30a is provided such that one end 324 in the second direction D2 extends long, and the other end 323 is provided shorter than the end 324. As shown in Fig. 6 , the other end 323 has a length such that it does not protrude outward in the second direction D2 beyond the edge of the solar cell 20. A length L23 of the inter-cell wiring 30a (second wiring portion 32) in the second direction D2 is longer than a length L21 of the solar cell 20. In this way, the length L23 in the second direction D2 of the inter-cell wiring 30a (second wiring portion 32) is set to a length such that one end 324 in the second direction D2 protrudes outside the edge of the solar cell 20 in the second direction D2, and the other end 323 does not protrude outside the edge of the solar cell 20 in the second direction D2.

[0057] The inter-cell wiring 30a including the short end 323 is not limited to being shorter at the right end in the drawing as shown in FIG. 7, but may also be shorter at the opposite left end in the drawing.

[0058] Fig. 8 is a plan view showing the solar cell module 1 according to embodiment 2 as seen from the back surface side. In the solar cell module 1, the solar cell strings constituting the solar cell string unit may be the solar cell string 11a shown in Fig. 6. The solar cell string unit 101 shown in Fig. 8 is configured such that an end 324 of the second wiring portion 32 extending from the solar cell string 11a is connected to an end 323 of the second wiring portion 32 extending from another adjacent solar cell string 11a.

[0059] In this case, the solar cell string 11a including the short end 323 of the inter-cell wiring 30a may be disposed at the end of the solar cell string unit 101 in the second direction D2, and may form a boundary between adjacent solar cell string units 101. The end 323 of the second wiring portion 32 of the inter-cell wiring 30a may be disposed apart from the end 323 of the second wiring portion 32 of the other adjacent solar cell string unit 101 without overlapping. When the inter-cell wirings 30a connected to adjacent solar cell strings 11a are disposed with their ends 323 facing each other in the second direction D2, the inter-cell wirings 30a do not overlap each other. Furthermore, when the ends 324 are disposed with their ends 324 facing each other in the second direction D2 or when the ends 323 and 324 are disposed with their ends 324 facing each other, the inter-cell wirings 30a overlap each other.

[0060] Therefore, the inter-cell wiring 30a can separate adjacent solar cell strings 11a by arranging the ends 323 thereof facing each other in the second direction D2. Furthermore, the inter-cell wiring 30a can also connect adjacent solar cell strings 11a by arranging the ends 324 thereof facing each other in the second direction D2 or by arranging the ends 323 and 324 thereof facing each other.

[0061] The solar cell module 1 is configured by electrically connecting two solar cell string units 101, 101 having a series-parallel connection structure via a transition wire 34. The transition wire 34 connects one solar cell string unit 101 to the other solar cell string unit 101 in series. The transition wire 34 connects the negative pole of one solar cell string unit 101 to the positive pole of the other solar cell string unit 101. More specifically, the transition wire 34 connects the first wiring portion 31 of the inter-cell wiring 30a at the negative pole side end of the solar cell string 11a constituting one solar cell string unit 101 to the first wiring portion 31 of the inter-cell wiring 30a at the positive pole side end of the solar cell string 11a constituting the other solar cell string unit 101.

[0062] In the solar cell module 1 according to this embodiment, the solar cell string unit 101 also has a connection structure for both series-connected solar cells 20 and parallel-connected solar cells 20. This eliminates the problem of a solar cell 20 being in a reverse bias state due to partial shading, whereby current flows through a parallel-connected circuit that bypasses that solar cell 20, resulting in a significant drop in power generation throughout the solar cell module. Furthermore, the solar cell module 1 according to this embodiment has two solar cell string units 101 connected in series. Therefore, the voltage is higher than that of the solar cell module of embodiment 1. In this way, by forming multiple solar cell string units 101 in one module and connecting them in series, desired solar cell module characteristics can be obtained.

[0063] To fabricate such a solar cell module 1, a conventional manufacturing process can be used in which solar cell strings 11a are first fabricated and then connected to each other. As in the first embodiment, the solar cell string unit 101 is fabricated by arranging multiple solar cell strings in the second direction D2 while aligning the polarity direction (series connection direction) of each solar cell string and connecting the second wiring portions 32 of adjacent inter-cell wirings 30a. This allows for high workability, easy alignment, and simple, accurate fabrication. The difference from the first embodiment is that the second embodiment includes a process of connecting the solar cell string units 101 in series. Because of the series connection, the polarity directions (series connection directions) of adjacent solar cell string units 101 are opposite to each other. Since the orientation only needs to be set for each solar cell string unit, this allows for high workability, easy alignment, and simple, accurate fabrication.

[0064] In addition, by arranging solar cell strings 11a using inter-cell wiring 30a in the second direction D2 with all the polarities aligned and connecting the long end 324 and short end 323 of opposing inter-cell wiring 30a, it is also possible to produce a solar cell module with the same connection structure as that shown in Figure 4 of embodiment 1.

[0065] Third Embodiment FIG. 9 is a plan view showing a solar cell module 1 according to a third embodiment as viewed from the back side, and FIG. 10 is an explanatory diagram showing a manufacturing method thereof.

[0066] The solar cell module 1 including the solar cell string 11a may be configured by combining a conventional solar cell string 80 with the solar cell string 11a shown in FIG.

[0067] 10 , in the conventional solar cell string 80, the length of the inter-cell wiring 81 in the second direction D2 is shorter than the length of the solar cell 20 in the second direction D2. In contrast, in the solar cell string 11a according to the embodiment of the present disclosure, as described above, the length of the inter-cell wiring 30a in the second direction D2 is longer than the length of the solar cell 20 in the second direction D2, and a short end 323 and a long end 324 are provided. Therefore, for example, it is also possible to configure the solar cell string unit 101 by connecting the long end 324 of the second wiring portion 32 to the inter-cell wiring 81 of the solar cell string 80.

[0068] 9 , three solar cell string units 101, each including these solar cell strings 11a, are electrically connected to one another by a connecting wire 34, thereby forming a solar cell module 1. The connecting wire 34 connects one solar cell string unit 101 in series with the other solar cell string unit 101. The connecting wire 34 connects the negative pole of one solar cell string unit 101 with the positive pole of the other solar cell string unit 101.

[0069] In the solar cell module 1 according to this embodiment, the solar cell string unit 101 can also be configured to have a connection structure for both series-connected solar cells 20 and parallel-connected solar cells 20, thereby eliminating the problem of reduced power generation due to partial shading. Furthermore, the solar cell module 1 according to this embodiment has three solar cell string units 101 connected in series, resulting in an even higher voltage than the solar cell module of embodiment 2. In this way, multiple solar cell string units 101 can be formed in one module and connected in series, and desired solar cell module characteristics can be obtained by setting any number of parallel and series connections.

[0070] Furthermore, to fabricate such a solar cell module 1, a conventional manufacturing process can be used in which solar cell strings 11a, 80 are first fabricated and then connected to each other. As in the second embodiment, the solar cell string unit 101 is fabricated by arranging multiple solar cell strings in the second direction D2 while aligning the polarity direction (series connection direction) of each solar cell string, and then connecting the second wiring portion 32 of the inter-cell wiring 30a to adjacent inter-cell wiring. This allows for high workability, easy alignment, and simple, accurate fabrication. Then, as in the second embodiment, the solar cell string units 101 are connected in series. Although the polarity directions (series connection direction) of adjacent solar cell string units 101 are opposite to each other, the orientation can be set for each solar cell string unit. This allows for high workability, easy alignment, and simple, accurate fabrication.

[0071] Note that the solar cell string unit and solar cell module according to the present disclosure are not limited to the above configurations and may be configured in various other ways. For example, the solar cell string constituting the solar cell string unit may be a combination of the solar cell string 11 shown in FIG. 1 and the solar cell string 11a shown in FIG. 6, or a combination of the solar cell string 11 shown in FIG. 1 and the conventional solar cell string 80 shown in FIG. 10. Furthermore, the solar cell string 11 shown in FIG. 1, the solar cell string 11a shown in FIG. 6, and the conventional solar cell string 80 shown in FIG. 10 may be combined. However, in either case, it is necessary to ensure that the ends 321 and 322 of the inter-cell wiring 30 and the long end 324 of the inter-cell wiring 30a, which are provided longer than the length of the solar cell 20 in the second direction D2, are not positioned so as to face the solar cell string units 101 adjacent in the D2 direction in the D2 direction.

[0072] (Embodiment 4) Fig. 11 is a plan view showing a solar cell string 12 according to embodiment 4 of the present disclosure. Fig. 12(a) and Fig. 12(b) show solar cells 40 constituting the solar cell string 12, Fig. 12(a) is a plan view showing the light-receiving surface side of the solar cell 40, and Fig. 12(b) is a plan view showing the back surface side of the solar cell 40. Fig. 13 is a plan view schematically showing an example of inter-cell wiring 50 of the solar cell string 12.

[0073] The solar cells 40 constituting the solar cell string 12 are flat photovoltaic elements that generate power when irradiated with light, and are double-sided electrode solar cells that include a front surface electrode 41 and a back surface electrode 42. As an example, as shown in FIG. 12( a), a front surface electrode 41 is provided on the light-receiving surface side of the solar cell 40, and includes, for example, a bus bar electrode and a finger electrode (not shown). The bus bar electrode of the front surface electrode 41 is provided linearly in a first direction D1 on the light-receiving surface of the solar cell 40. The finger electrodes are formed linearly from the bus bar electrode in a second direction D2.

[0074] 12(b), the back surface electrode 42 is provided opposite the front surface electrode 41, and includes, for example, bus bar electrodes and finger electrodes (not shown). The bus bar electrodes of the back surface electrode 42 are provided linearly in the first direction D1 on the back surface of the solar cell 40. The finger electrodes are formed linearly from the bus bar electrodes in the second direction D2.

[0075] A plurality of pads 43 are provided on the busbar electrodes (collecting electrodes) to improve adhesion with wiring materials such as wires and to reduce contact resistance for connection, and end pads 44 are also provided on the ends of the solar cell 40 in the first direction D1. These pads 43 and end pads 44 have a relatively wide width and can serve as regions for attaching and fixing the first wiring portions 51 of the inter-cell wiring 50 and the like.

[0076] 13 , the inter-cell wiring 50 includes a plurality of first wiring portions 51 (51 a, 51 b) extending in a first direction D1 and a second wiring portion 52 extending in a second direction D2 so as to intersect with the first wiring portions 51. The plurality of first wiring portions 51 are arranged in accordance with the shape of the cell electrodes, and in the illustrated embodiment, are arranged symmetrically with respect to the strip-shaped second wiring portion 52 that is long in the second direction D2.

[0077] The first wiring portion 51 is a wire-shaped (or linear) conductive member. Specifically, the first wiring portion 51 is a wire-shaped wiring material (interconnector wire) having a configuration in which the outer surface of a wire having a substantially circular cross section is coated with a conductive adhesive or solder. The material of the wire is not particularly limited, but may be a metal such as copper.

[0078] As shown in FIG. 11 , the second wiring portion 52 of the inter-cell wiring 50 has a length L25 in the second direction D2 that is longer than the length L24 of the solar cell 40 in the second direction D2. An end 521 of the second wiring portion 52 extends to one side of the inter-cell wiring 50 in the second direction D2, and an end 522 of the second wiring portion 52 extends to the other side of the second direction D2. The second wiring portion 52 may be a wire-shaped, linear, or strip-shaped conductive member, and its outer surface may be coated with a conductive adhesive or solder. The length L25 of the second wiring portion 52 of the inter-cell wiring 50 in the second direction D2 is such that both ends (521, 522) of the second wiring portion 52 protrude outward in the second direction D2 beyond the edge of the solar cell 40. Furthermore, the length L25 of the second wiring portion 52 in the second direction D2 is shorter than 1.5 times the length L24 of the solar cell 40 in the second direction D2.

[0079] Furthermore, the length L26 ( FIG. 13 ) in the first direction D1 of the inter-cell wiring 50 including the first wiring portions 51 a, 51 b is shorter than the length L27 ( FIG. 11 ) in the first direction D1 of two solar cell cells 40, 40 adjacent to each other in the first direction D1. The inter-cell wiring 50 may have an opening in the second wiring portion 52. The inter-cell wiring 50 may have an opening at an intersection between the first wiring portion 51 and the second wiring portion 52. The opening may be formed at each intersection between the first wiring portion 51 and the second wiring portion 52. The opening may have a shape that is longer in the second direction D2 than in the first direction D1, and may be an ellipse, a slit, a rectangle, or a rounded, approximately rectangular shape. The openings may be arranged at equal intervals along the second wiring portion 52.

[0080] In the solar cell string 12, the first wiring portion 51a extending in one direction in the first direction D1 of the inter-cell wiring 50 is connected to the front surface electrode 41 of one of two solar cell cells 40, 40 adjacent to each other in the first direction D1, and the first wiring portion 51b extending in the other direction in the second direction D2 is connected to the back surface electrode 42 of the other solar cell 40. The first wiring portion 51 is connected to the front surface electrode 41 and the back surface electrode 42 of the solar cell 40 by a conductive adhesive such as solder or conductive paste. The multiple solar cell cells 40 arranged adjacent to each other in the first direction D1 are electrically connected in series by the first wiring portions 51a, 51b extending in the first direction D1.

[0081] Even in such a configuration, the solar cell string 12 shown in Fig. 11 can be fabricated by arranging a plurality of solar cells 40 along the first direction D1 and electrically connecting the solar cells 40 adjacent to each other in the first direction D1 in series with the inter-cell wiring 50 (string fabrication process). The number of solar cells 40 constituting the solar cell string 12 is not limited to the illustrated number.

[0082] 14 is a plan view showing a solar cell module 1 according to embodiment 4. The solar cell strings 12 fabricated in the string fabrication step have second wiring portions 52 extending in the second direction D2, so when fabricating the solar cell module 1, for example, one end 521 of the second wiring portion 52 can be connected to, by overlapping with, the other end 522 of the second wiring portion extending from another solar cell string 12 adjacent in the second direction D2. The solar cell string unit 100 can be fabricated by connecting the second wiring portions 52 of a predetermined number of solar cell strings 12 together.

[0083] The solar cell module 1 including the solar cell string 12 and solar cell string unit 100 configured in this manner also has a connection structure for both series-connected solar cells 40 and parallel-connected solar cells 40. Therefore, even if a solar cell 40 becomes reverse-biased due to partial shading, current flows through a parallel-connected circuit that bypasses that solar cell 40, eliminating the problem of a significant drop in power generation across the entire solar cell module, and making it possible to stabilize the power generation. Moreover, to fabricate such a solar cell module 1, the same manufacturing process as in the past can be used, in which solar cell strings 12 are first fabricated and then the solar cell strings 12 are connected together.

[0084] 16 , solar cell module 90a having a conventional structure is configured such that solar cell strings 93 are first formed by connecting solar cell cells 91 in series, and then the solar cell strings 93 are connected in series. Therefore, the polarities of adjacent solar cell strings 93 (series connection directions) are opposite to each other.

[0085] In contrast, the solar cell module 1 according to this embodiment differs from conventional solar cell modules in that adjacent inter-cell wirings 50 can be connected to each other while aligning the polarity directions (series connection direction) of the solar cell strings 12, which makes it easy to work with and align the positions, and allows for simple and accurate fabrication.

[0086] 13 , the length L25 of the second wiring portion 52 in the second direction D2 is longer than the length L24 of the solar cell 40 in the second direction D2, and the second wiring portion 52 extends on both sides in the second direction D2. However, the second wiring portion 52 may extend on only one side in the second direction D2. The length L25 of the second wiring portion 52 of such an inter-cell wiring member 50 in the second direction D2 is set to a length such that only one end in the second direction D2 protrudes outward in the second direction D2 beyond the edge of the solar cell 40, and the other end does not protrude outward in the second direction D2 beyond the edge of the solar cell 40. Furthermore, a solar cell string unit may be formed by appropriately combining inter-cell wirings 50 in which the second wiring portion 52 extends on both sides in the second direction D2, in which the second wiring portion 52 extends on only one side, and in which the second wiring portion 52 does not extend on either side in the second direction D2.

[0087] FIG. 15 is a plan view showing another example of the solar cell module 1 according to the fourth embodiment. For example, as shown in FIG. 15 , the solar cell string unit 101 includes at least one solar cell string 12 using inter-cell wiring 50 in which the second wiring portion 52 extends only in one direction in the second direction D2 and does not extend in the other direction. In this case, the solar cell string unit 101 can also be fabricated by connecting adjacent inter-cell wiring 50 while aligning the polarity of the solar cell strings 12. In one solar cell module 1, multiple solar cell string units 101 can be configured to be connected in series with appropriate wiring material 53. The number of solar cell strings 12 constituting one solar cell string unit 101 is not limited to the example shown and can be set as desired.

[0088] In this way, multiple solar cell string units 100, 101 can be formed in one solar cell module 1 and connected in series, and by setting any number of parallel and series connections, desired solar cell module characteristics can be obtained.

[0089] Furthermore, to fabricate such a solar cell module 1, a conventional manufacturing process can be used in which solar cell strings are first fabricated and then connected to each other. The solar cell string unit 100 including at least one solar cell string 12 using inter-cell wiring members 50 protruding on both sides, and the solar cell string unit 101 including at least one solar cell string 12 using inter-cell wiring members 50 protruding on only one side, can both be fabricated simply by connecting the second wiring portions 52 of the inter-cell wiring 50 while aligning the polarity directions (series connection directions) of the solar cell strings 12, thereby enabling high workability, easy alignment, and simple, accurate fabrication. To fabricate the solar cell module 1 shown in FIG. 15 , solar cell string units 101 are connected in series, and the polarity directions (series connection directions) of adjacent solar cell string units 101 are opposite to each other. However, since the orientation only needs to be set for each solar cell string unit, high workability, easy alignment, and simple, accurate fabrication are possible.

[0090] By providing a solar cell module having the structure of the present disclosure, it is possible to provide a solar cell module that can suppress the effect of a decrease in power generation due to partial shading and increase the effective power generation amount. Furthermore, by appropriately using strings such as solar cell strings 11, 11a, and 12 in a solar cell module, it is possible to arbitrarily select the number of solar cells connected in series and in parallel, thereby providing a solar cell module with desired electrical characteristics.

[0091] According to the embodiments of the present disclosure relating to each of these configurations, it is possible to configure a solar cell module that can reduce the effect of reduced power generation due to partial shading and increase the actual amount of power generation.

[0092] The solar cell string, solar cell string unit, and solar cell module according to the present disclosure are not limited to the above-described configurations, and may be configured in various other forms. For example, the solar cell module may be suitably implemented as a solar cell module having a curved surface.

[0093] The types of solar cells included in the solar cell module are not limited to those illustrated, and can be made of various semiconductor materials, such as polycrystalline semiconductors and compound semiconductors. Furthermore, the solar cell is not limited to the standard-sized cell illustrated (a cell equivalent to one solar cell wafer, also called a full cell), but may also be a cell obtained by dividing a standard-sized cell in half (half cell), or a divided cell, such as a cell divided into one-third or one-quarter. The solar cell module can be configured with multiple solar cell cells arranged in various ways in the first direction D1 and the second direction D2. The light-receiving surface protective member included in the solar cell module can be selected from transparent glass or a resin material, and the back surface protective member can be selected from a back sheet, transparent glass, or a resin material.

[0094] The present invention can be embodied in various other forms without departing from its spirit or essential features. Therefore, the above-described embodiments are merely illustrative in all respects and should not be interpreted as limiting. The scope of the present invention is defined by the claims and is not limited to the text of the specification. Furthermore, all modifications and variations within the equivalent range of the claims are within the scope of the present invention.

[0095] This application claims priority based on Japanese Patent Application No. 2023-215205, filed in Japan on December 20, 2023, the entire contents of which are incorporated herein by reference.

[0096] REFERENCE SIGNS LIST 1 Solar cell module 11, 11a, 12 Solar cell string 100, 101 Solar cell string unit 20, 40 Solar cell 21 Semiconductor substrate 231 First conductivity type cell electrode 232 Second conductivity type cell electrode 241 First collector electrode 242 Second collector electrode 30, 30a, 50 Inter-cell wiring 31, 51 First wiring section 32, 52 Second wiring section 33 Opening 34 Jumper wiring 41 Surface electrode 42 Back electrode D1 First direction D2 Second direction

Claims

1. A solar cell string comprising a plurality of solar cells arranged along a first direction and electrically connected by inter-cell wiring, wherein the inter-cell wiring comprises a first wiring portion extending in the first direction and a second wiring portion connected to the first wiring portion and extending in a second direction intersecting the first direction, and is arranged at least between adjacent solar cells in the first direction, the first wiring portion is connected to an electrode of the solar cell, and the second wiring portion is longer than the length of the solar cell in the second direction and shorter than 1.5 times the length of the solar cell in the second direction, and at least one end in the second direction extends further in the second direction than the solar cell.

2. A solar cell string unit including a plurality of solar cell strings, each solar cell string having a plurality of solar cells arranged along a first direction electrically connected by inter-cell wiring, the inter-cell wiring comprising a first wiring portion extending in the first direction and a second wiring portion connected to the first wiring portion and extending in a second direction intersecting the first direction, the plurality of solar cell strings being arranged side by side in the second direction, at least one of the plurality of solar cell strings arranged in the second direction being the solar cell string A described in claim 1, and the second wiring portion extending from the solar cell string A being connected to the second wiring portion of another adjacent solar cell string.

3. A solar cell string unit as described in claim 2, characterized in that a plurality of the solar cell cells adjacent to each other in the first direction are connected by the inter-cell wiring and electrically connected in series, and a plurality of the solar cell cells adjacent to each other in the second direction are connected by the inter-cell wiring and electrically connected in parallel.

4. A solar cell module comprising at least one solar cell string unit according to claim 3.

5. A solar cell module according to claim 4, wherein the solar cell is a back electrode type solar cell having the electrode on one side of a semiconductor substrate.

6. A solar cell module as described in claim 5, characterized in that the solar cell includes a first conductivity type cell electrode and a second conductivity type cell electrode as the electrodes, a first collector electrode connected to the first conductivity type cell electrode is provided on one side of the first direction of the semiconductor substrate, and a second collector electrode connected to the second conductivity type cell electrode is provided on the other side of the first direction, and the first wiring portion of the inter-cell wiring is connected to the first collector electrode of one of the two solar cell adjacent to each other in the first direction and the second collector electrode of the other solar cell.

7. A solar cell module according to claim 4, characterized in that the inter-cell wiring has an opening at the intersection of the first wiring portion and the second wiring portion.

8. A solar cell module as described in claim 4, wherein the solar cell is a double-sided electrode type solar cell having as the electrodes a surface electrode on the light-receiving surface side and a back electrode on the surface opposite the light-receiving surface, and the first wiring portion extending in one direction in the first direction of the inter-cell wiring is connected to the surface electrode of one of two solar cell adjacent in the first direction, and the first wiring portion extending in the other direction in the first direction is connected to the back electrode of the other solar cell.

9. A method for manufacturing a solar cell module having a solar cell string unit including a plurality of solar cell strings, comprising: a string fabrication process for arranging a plurality of solar cells having electrodes on a semiconductor substrate along a first direction, and electrically connecting the solar cells adjacent to each other in the first direction in series with inter-cell wiring to fabricate the solar cell string, the inter-cell wiring comprising a first wiring portion extending in the first direction and a second wiring portion connected to a plurality of the first wiring portions and extending in a second direction intersecting the first direction, the second wiring portion being longer than a length of the solar cell in the second direction, the string fabrication process connecting the first wiring portion to electrodes of the solar cell, and after the string fabrication process, connecting the second wiring portion extending from the solar cell string to the inter-cell wiring of another solar cell string adjacent to each other in the second direction to fabricate the solar cell string unit.

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