Solar Panels

Abstract

To make it possible to take out power generation current of cells even when one of the cells is covered with a partial shadow in a solar panel having a group of cells where a plurality of cells are disposed in a shingling structure.SOLUTION: A solar panel includes a group 1 of cells where a plurality of solar battery cells 2 are aligned in one direction so that an edge part on one surface of the adjacent solar battery cells overlaps an edge part on the other reverse surface, and connecting elements 3a, 3b electrically connecting the plurality of solar battery cells are disposed between the overlapping edge parts 2c and on a reverse side surface 2b of the solar battery cells. In the group of cells, a plurality of parallel connection regions R where at least two solar battery cells are mutually electrically connected in parallel are formed and the plurality of parallel connection regions are electrically serially connected.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a solar panel, and more particularly to a solar panel configured so that as many solar cells as possible can be arranged without gaps within a certain limited area. [Background technology]

[0002] In order to achieve carbon neutrality, attempts are being made to mount solar panels on the roofs of vehicles such as automobiles or other mobile bodies and use the solar energy obtained thereby to drive the vehicle. When installing solar panels on the roofs of such mobile bodies, the area in which the solar panels can be arranged is limited, so various configurations have been proposed to arrange as many solar cells as possible on the panel without gaps so that as much solar energy as possible can be collected and power generated within a certain limited area. For example, Patent Documents 1 and 2 propose using a "shingling structure" or "shingling method" in which, when arranging multiple solar cells in one direction on a panel, the back surface (back side surface) of a certain solar cell is arranged so as to partially overlap the edge of the front surface (front side surface) of an adjacent solar cell, and adjacent solar cells are electrically connected to each other via a conductive member at the overlapping portion (see FIG. 4(A)). In particular, Patent Document 1 proposes an arrangement configuration that can suppress a decrease in output when arranging multiple solar cells with different power generation areas in a configuration in which multiple cells arranged in a shingling structure are connected in series. Furthermore, Patent Document 2 describes that by arranging multiple solar cells in series connected in a shingling manner (strings) in a direction intersecting the arrangement direction of the solar cells and using common components to electrically connect adjacent solar cells in each string (each cell is connected in series with other cells in one string and in parallel with corresponding cells in other strings), it is expected that output reduction due to current mismatches between multiple strings can be suppressed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-082722 [Patent Document 2] International Publication 2020 / 031574 Summary of the Invention [Problem to be solved by the invention]

[0004] In a solar panel, for example, if the entire area where sunlight reaches (sunlight reaching area) is covered with a single solar cell (hereinafter referred to as a "cell"), the generated voltage will be low, the generated current will be large, and the amount of heat (Joule heat) will be large. In order to avoid this, a configuration is adopted in which multiple cells are arranged in the sunlight reaching area and connected in series to increase the generated voltage in the panel and reduce the generated current, as described above. In addition, rather than forming a single cell that covers the sunlight reaching area, it is advantageous to arrange multiple small-area cells in parallel as appropriate to match the shape of the sunlight reaching area, which makes it easier to manufacture, install, and operate the solar panel. In this case, if the above-mentioned shingling structure is adopted, multiple cells can be arranged almost without gaps in the sunlight reaching area, so that almost the entire area of ​​the sunlight reaching area is covered with the light receiving surface of the cell, and it is possible to obtain as much solar energy as possible from the panel as electrical energy.

[0005] In a solar panel adopting the above-mentioned shingling structure, typically, a group of cells called a "string" is formed by arranging a plurality of cells in one direction and electrically connecting them in series, and one or more cell groups are arranged in the solar light reaching area of ​​the panel so as to cover the entire area. In this case, since all the cells in each cell group are connected in series, the magnitude of the generated current obtained in each cell group is limited to the magnitude of the generated current of the cell with the smallest generated current among the cells in the cell group. Therefore, when a partial shadow is formed in the solar light reaching area of ​​the panel and the amount of light received by some cells is reduced, the generated current of the cell with the reduced amount of light received is reduced (the generated current of each cell increases or decreases in response to the increase or decrease in the amount of light received by each cell), and the generated current obtained from the cell group to which the cell belongs is also reduced. For example, when the entire surface of a cell is in the partial shadow, no current flows through that cell, and no current flows through the cell group to which the cell belongs. In addition, in a solar panel with a shingled structure as shown in FIG. 5(A), the solar light reaching area is covered by multiple cells, so the area of ​​the light receiving surface of each cell is smaller than the solar light reaching area of ​​the panel. When a partial shadow of a certain size occurs on one cell, the smaller the light receiving area of ​​the cell, the greater the current drop rate. Therefore, in a cell group with a shingled structure in which all cells are connected in series, the drop rate of the generated current when a certain partial shadow occurs is greater than the drop rate of the generated current when a cell with the same area as the cell group experiences the same partial shadow. Furthermore, in a solar panel with a string of multiple shingled cell groups arranged side by side as shown in FIG. 5(B), if a long and narrow shadow (such as a shadow caused by a tree or utility pole) that covers one cell in each cell group occurs, when all the cells in each cell group are connected in series, no current is obtained in all the cell groups, and no power can be extracted. Therefore, in a solar panel, in which the area reaching the sunlight is configured with multiple cells arranged in a so-called "shingling structure," it is advantageous if, even if a partial shadow is created that covers one cell, the generated current of the other cells can be extracted from the cell group to which the cell belongs.

[0006] Thus, one object of the present invention is to provide a solar panel configured in a cell group consisting of multiple cells arranged in a shingling structure, which allows the generation current of the other cells to be extracted even if one cell is partially shaded. [Means for solving the problem]

[0007] According to one aspect of the present invention, the above object is achieved by providing a solar panel, comprising: a cell group in which a plurality of solar cells are arranged in one direction, the edge portion of a front side surface of one of the solar cells adjacent to each other is arranged to overlap an edge portion of a rear side surface of the other solar cell, and connection elements are arranged between the overlapping edge portions and on the rear sides of the solar cells to electrically connect the plurality of solar cells to each other; In the cell group, a plurality of parallel connection regions are formed in which at least two solar cells are electrically connected in parallel, and the parallel connection regions are electrically connected in series to form a solar panel. This is achieved by:

[0008] In the above-mentioned configuration of the present invention, the "solar cell" may be any type of solar cell that is normally used in this field. As described above, a "cell group" in which a plurality of such "solar cells" are arranged in one direction is arranged so that the edge portion of one of the front surfaces of adjacent solar cells overlaps the edge portion of the back surface of the other solar cell, forming a so-called "shingling structure". In addition, on the front surface (front side surface) of each solar cell, substantially the entire area may be a light receiving surface, except for the edge portion that overlaps with the edge portion of the back surface (back side surface) of the adjacent solar cell (the edge portion that overlaps with the edge portion of the back side surface of the adjacent solar cell may also be formed in the same manner as the light receiving surface), and thus it is possible to form the front side surface, which is the solar light reaching area of ​​the cell group, so that substantially the entire area is a light receiving surface. In addition, a bypass diode may be connected in parallel between both ends of the cell group in a normal manner.

[0009] In the cell group of the solar panel of the present invention, the multiple cells arranged in one direction are not all connected in series, but multiple parallel connection areas are formed in which at least two solar cells are electrically connected in parallel, and the multiple parallel connection areas are electrically connected in series. That is, between the multiple cells arranged in one direction, there are formed a portion in which adjacent cells are electrically connected in parallel and a portion in which adjacent cells are electrically connected in series. Note that adjacent cells being electrically connected in parallel means that the anodes and cathodes of the cells are electrically connected to each other, and adjacent cells being electrically connected in series means that one cathode of adjacent cells is electrically connected to the other anode.

[0010] According to the above-mentioned configuration of the present invention, first, in the cell group, the multiple cells are arranged in a shingled structure, and the connection elements that electrically connect the multiple solar cells to each other are arranged between the overlapping edge parts of the adjacent cells and on the back surface of the solar cell, so that it is possible to arrange the light receiving surface on the front side of the cell group in substantially the entire area of ​​the solar light reaching area, and it is possible for the cells to receive as much solar light as possible within the area occupied by the cell group. In addition, in the configuration of the present invention, since each cell in the cell group is connected in parallel with at least one other cell, even if the cell is covered in partial shade and cannot generate power, as long as the cell connected in parallel with the cell is in a state where it can generate power, the generated current generated by the other cells in the cell group can flow, and it is possible to extract the generated current from the cell group. In other words, according to the above-mentioned present invention, even if one cell in the cell group is covered in partial shade, the generated current flows through the cell group, and it is possible to extract the electric energy converted from the solar energy.

[0011] In the above-mentioned configuration of the present invention, the cell group may be configured so that the light receiving areas on the front side surface of each of the plurality of solar cells are equal to each other, and in this case, the number of solar cells connected in each of the plurality of parallel connection regions is equal to each other. As a result, when partial shading does not occur in the cell group, the generated current flowing out from each parallel connection region is equal, so that the generated current in any cell is not limited, and it is possible to efficiently extract solar energy as electrical energy. In addition, the solar panel of the present invention may include a plurality of cell groups, and the plurality of cell groups may be electrically connected to each other in series or parallel. However, when the light receiving areas on the front side surface of each of the plurality of solar cells are equal to each other, and the number of solar cells connected in each of the plurality of parallel connection regions is equal to each other, as described above, the number of solar cells included in each of the plurality of cell groups may be equal to each other and the number of solar cells connected in the parallel connection regions may be equal to each other. With such a configuration, the generated voltage and generated current obtained in each cell group are equal to each other, so even if multiple cell groups are connected in series or parallel, the generated voltage and generated current of any of the cell groups are not limited. Furthermore, the generated voltage and generated current of each cell are not limited by the generated voltage and generated current of the other cells, so it is possible to more efficiently extract solar energy as electrical energy.

[0012] In the embodiment of the configuration of the present invention described above, in order to achieve a configuration in which some adjacent cells are electrically connected in parallel and other adjacent cells are electrically connected in series in a cell group, as for the connection elements electrically connecting the cells, in the portion where adjacent parallel connection regions are electrically connected in series, the connection elements electrically connecting two adjacent solar cells are arranged between the overlapping edge portions of the two solar cells, and in the parallel connection region, an insulating material layer is arranged on the back side of each solar cell where an anode connection element connecting the anodes of the solar cells connected in parallel to each other is arranged, and such anode connection element may be arranged on the surface of the insulating material layer (a cathode connection element connecting the cathodes of the solar cells connected in parallel to each other may be directly attached to the back side of the cell), and the overlapping edge portions of the solar cells connected in parallel to each other may be insulated. With such a configuration, it is possible to mix a portion where cells are connected in series and a portion where cells are connected in parallel with a simple configuration in the cell group without arranging a connection element (for electrically connecting the cells) on the sunlight receiving surface (front side). [The finger electrodes for current collection on the front side of the cells may be disposed on the front side, instead of the connection elements for electrically connecting the cells.] Effect of the Invention

[0013] Thus, in the solar panel device of the present invention, since a plurality of parallel connection regions, each of which has at least two cells connected in parallel, are connected in series, the generated voltage obtained from the cell group can be higher than that obtained when the same area is covered by a single cell. Even if a certain cell in the cell group is partially shaded and the generated current does not flow, if the cell connected in parallel to the certain cell is in a state where the generated current flows, the generated current can flow from the other cells, so that the generated current can be taken out from the cell group, thereby making it possible to obtain electric power. In this regard, the configuration of the present invention is advantageously used in a solar panel device mounted on a moving body such as a vehicle. That is, in the case of a solar panel device mounted on a moving body, a partial shadow that changes from moment to moment may enter the light receiving surface of the panel while the moving body is moving around. Also, for example, while a mobile body equipped with a solar panel in which multiple cell groups are arranged in parallel is traveling, a long and narrow partial shadow from a roadside tree, utility pole, billboard, etc. may enter the light receiving surface of the panel, and each cell in the multiple cell groups may be partially shaded as shown in Fig. 5(B). In such a situation in which partial shadows enter the light receiving surface in various ways from moment to moment, if all cells are connected in series in a single-cell group with a shingling structure as in the past, every time one of the cells is partially shaded, it becomes impossible to extract power from that cell group. In particular, in a mobile body equipped with a solar panel in which multiple cell groups are arranged in parallel, when each cell in the multiple cell groups is partially shaded as shown in Fig. 5(B), it becomes impossible to obtain power generation energy from the entire panel just by a single long and narrow partial shadow entering the light receiving surface, and it may become impossible to generate power stably and continuously. However, in the configuration of the present invention described above, each cell in the cell group is connected in parallel with at least one other cell, so that even if one cell in one cell group or in all cell groups is partially shaded, the generated current flows to another cell, making it possible to generate power more uninterruptedly and stably, which is advantageous.

[0014] Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the invention. [Brief description of the drawings]

[0015] [Figure 1] Fig. 1(A) is a schematic side view of a solar panel according to the present embodiment, and Fig. 1(B) is a bottom view of the solar panel according to the present embodiment. Fig. 1(C) is a wiring circuit diagram of one aspect of the solar panel according to the present embodiment. Fig. 1(D) is a wiring circuit diagram of another aspect of the solar panel according to the present embodiment. [Diagram 2] Figure 2 shows the voltage-output characteristics between both ends of a cell group in which 10 cells are arranged in a shingled structure, when the cells are connected according to this embodiment (this example) and when all cells are connected in series (series), when there is no shadow (no shadow), when half of a cell is covered in shadow (0.5 cell shadow), and when a cell is entirely covered (1 cell shadow). [Diagram 3] FIG. 3 is a schematic plan view of a state in which a plurality of cell groups according to this embodiment are connected together. [Figure 4] Fig. 4(A) is a schematic perspective view of a cell group in which cells are arranged in a shingled structure. The top is a diagram in which the cells are separated so that the relationship between the stacked cells can be seen, and the bottom is a diagram of the cells stacked on top of each other. Fig. 4(B) is a schematic side view of a configuration in which all cells are connected in series in a cell group in which cells are arranged in a shingled structure. Fig. 4(C) is a wiring circuit diagram of a configuration in which all cells are connected in series. [Diagram 5] Fig. 5(A) is a schematic plan view of a cell showing a state where partial shadows of the same size are cast on cells of different areas, and Fig. 5(B) is a schematic plan view of multiple cell groups arranged side by side, showing a state where elongated partial shadows are cast over all of the cell groups. [Explanation of symbols]

[0016] 1...Cell group 2…Cell 2a…Front side of the cell 2b…Back side of the cell 2c…Cell overlapping edge 3. Connection elements 3a...Cell cathode terminal or cathode connector 3b...Cell anode terminal or anode connector 4…Insulating material layer S: Series connection point P: Parallel connection point Sh…partial shadow R: Parallel connection area BPD: Bypass diode BEST MODE FOR CARRYING OUT THEINVENTION

[0017] Configuration of shingled cell group As already described with reference to FIG. 4(A), in a cell group consisting of a plurality of solar cells of a so-called "shingled structure", when the plurality of cells are arranged in one direction, the edge portion of each cell is overlapped with the edge portion of the adjacent cell, that is, in the figure, the back side of the edge portion of the right end side of each cell is placed on the front side of the edge portion of the left end side of the adjacent cell. In the case of the shingled structure, generally, a connection element (connection terminal, conductive wire, connector, etc.) for electrical connection between the cells is provided between the overlapping edge portions of each adjacent cell, so that it is possible to receive the sunlight by arranging the light receiving surface in substantially the entire area of ​​the exposed front side (sunlight reaching area) of the cell group where the sunlight reaches, and it is possible to receive substantially the maximum amount of sunlight in the area occupied by the cell group. As a result, the cell group of the shingled structure is advantageous when it is desired to recover as much solar energy as possible as electrical energy in a limited area, such as the roof of a mobile body.

[0018] In the case of the conventional configuration of the cell group having the above-mentioned shingled structure, typically, in a row of the cell group, all the cells are electrically connected in series as shown in FIG. 4(B). In this case, in the overlapping edge portion 2c between two adjacent cells 2, the cathode terminal 3a of the cell arranged in the edge portion of the back side surface 2b of the cell placed on the top is matched and connected to the anode terminal 3b of the cell arranged in the edge portion of the front side surface 2a of the cell placed on the bottom, and this configuration is repeated in order along the cell group, thereby achieving the series connection of all the cells without the connection elements between the cells occupying the sunlight-reaching area on the top surface of the cell group. However, in the case of the cell group in which all the cells are connected in series as described above, as can be understood from the circuit diagram of FIG. 4(C), the current flowing through the cell group is limited to the magnitude of the current flowing through the cell with the smallest power generation current among the cells connected in series. Therefore, when sunlight is evenly irradiated onto all cells, the current of any cell is not limited, but when the amount of light received by one cell in a cell group is reduced due to partial shading, not only does the generated current of that cell decrease, but the overall current flowing through the cell group also decreases, resulting in a decrease in the electrical energy that can be extracted from the cell group. Furthermore, when a partial shadow is cast completely over a cell, it is not possible to extract current from the cell group to which that cell belongs, and therefore electrical energy cannot be obtained.

[0019] In addition, in a group of cells with a shingled structure, the light receiving area of ​​each cell is generally relatively small, and when cells with different areas are partially shaded with the same area, the smaller the area of ​​the cell, the larger the current drop rate becomes. For example, as shown in FIG. 5(A), when a partial shadow Sh with an area of ​​α / k is cast on a cell with an area of ​​α (left) and a cell with an area of ​​α / n (right) (n is a positive number greater than 1), the current is (k-1) / k times larger in the cell with an area of ​​α, and (k / n-1)k times larger in the cell with an area of ​​α / n, so the drop rate of the current is larger in the latter. That is, when the area of ​​each cell is small, as in a group of cells with a shingled structure, the drop rate of the current due to a partial shadow of a certain area becomes relatively large, so that the current flowing through the group of cells is more likely to drop. [As shown in FIG. 4(C), when bypass diodes BPD are connected in parallel to both ends of cell group 1, if the current that can flow through cell group 1 decreases, current will flow to the bypass diode BPD, and cell group 1 will not output any power at all.]

[0020] Furthermore, for example, in a solar panel in which multiple cell groups 1 are arranged side by side as shown in Fig. 5(B), when multiple cells in each cell group are all connected in series, when a long and narrow partial shadow Sh is cast across the multiple cell groups as shown in the figure, power cannot be extracted from all of the multiple cell groups even though only one cell in each cell group is in the partial shadow. Such long and narrow partial shadows Sh are often cast on the roof of a moving body such as a vehicle due to the shadow of roadside trees or utility poles while the moving body is moving, and in a configuration in which a solar panel as shown in Fig. 5(B) is mounted on the roof of a moving body, a state in which no power can be obtained at all may occur frequently every time such a long and narrow partial shadow Sh is cast on the moving body while the moving body is moving.

[0021] Configuration of a cell group having a shingling structure according to this embodiment As described above, when all the cells in a cell group are connected in series, if even one cell in the cell group is partially shaded, no current flows through the cell group, and power cannot be collected. Therefore, in this embodiment, in a cell group in which a plurality of cells are arranged to form a shingling structure, each cell is connected in parallel with at least one other cell, and the cells are electrically connected to each other so that a set of cells connected in parallel to each other (parallel connection area) is connected in series. With this configuration, even if a certain cell in the cell group is partially shaded and no generated current flows, if other cells connected in parallel to that cell are not partially shaded, the generated current flows through the cell group through the other cells, and the state in which power can be extracted from the cell group is maintained.

[0022] Specifically, when viewed from the front side, the cell group in the solar panel device of this embodiment has multiple cells 2 arranged in one direction, as in Figure 4(A), so that the edge portion of each cell overlaps the edge portion of an adjacent cell, i.e., in the figure, the back side of the edge portion of the right end side of each cell is placed on the front side of the edge portion of the left end side of the adjacent cell, and the light receiving surface is arranged over substantially the entire sunlight reaching area of ​​the cell group 1, thereby enabling substantially the maximum amount of sunlight to be received in the area occupied by the cell group. 1(A) and 1(B), however, in the case of this embodiment, in the portion between cells marked with P (parallel connection portion), adjacent cells 2 are electrically connected in parallel to each other, and in the portion between cells marked with S (series connection portion), adjacent cells 2 are electrically connected in series to each other, so that cathode connectors 3a and anode connectors 3b connecting the cells are disposed between overlapping edge portions 2c of adjacent cells 2 and on the back side surface 2b of each cell 2. In this embodiment, in the cell group 1 arranged in a shingling structure, a plurality of regions (parallel connection regions) R in which adjacent cells 2 are connected in parallel are formed, and wiring is performed between the cells so that these parallel connection regions R are connected in series.

[0023] 1(A) and (B), the configuration in which the parallel connection regions R in which adjacent cells 2 are connected in parallel as described above are connected in series can be achieved, for example, by configuring and arranging the cathode connector 3a and the anode connector 3b as follows: First, in each of the series connection parts S in which the cells are connected in series, a cathode connector 3a extending over the entire length in the extension direction of the cell group 1 is arranged on the back side surface 2b of the cell 2 stacked on the upper side (located on the left in the figure), and at the series connection part S, an end of the cathode connector 3a faces and matches with an end of the anode connector 3b arranged on the edge portion of the front side surface 2a of the cell 2 stacked on the lower side (located on the right in the figure), thereby achieving a series connection between the two adjacent cells 2 at the overlapping edge portion 2c. Next, in the cell 2 stacked below each series connection site S, the anode connector 3b is configured and arranged to extend from the end of the front side surface 2a of the overlapping edge portion 2c of the series connection site S, down along the side edge of the cell 2, and along the back side surface 2b of the cell 2 to the other edge portion where the parallel connection site P is formed, over the entire length in the extension direction of the cell group 1 (to the right in the figure). Note that in the cell 2 stacked below the series connection site S, an insulating material layer 4 is laminated on the back side surface 2b as shown in the figure, and the anode connector 3b is arranged on the surface of the insulating material layer 4, thereby providing electrical insulation between the back side surface 2b and the anode connector 3b.

[0024] Meanwhile, at each parallel connection portion P, the end of the anode connector 3b, which is disposed via an insulating material layer 4 so as not to come into contact with the back side 2b of the cell 2 stacked above (located on the left in the figure), comes into contact with the edge portion of the front side 2a of the cell 2 stacked below (located on the right in the figure). The anode connector 3b comes into contact with the front side 2a of the cell 2 stacked above at the overlapping edge portion 2c of the other end (at the series connection portion S in the figure) of the cell 2 stacked above, thereby connecting the front sides 2a, which are the anodes, of the cell 2 stacked above and the cell 2 stacked below at the parallel connection portion P. Furthermore, at each parallel connection site P, the cathode connector 3a in contact with the back surface 2b of the cell 2 stacked below moves up the side wall from the back surface 2b of that cell 2 to contact the back surface 2b of the cell 2 stacked above so as not to contact the anode connector 3b, thereby connecting the back surfaces 2b, which are the cathodes, of the cell 2 stacked above and the cell 2 stacked below at the parallel connection site P, and thus achieving a parallel connection between two adjacent cells 2 at the parallel connection site P.

[0025] As described above, in the cell group 1 in the present embodiment, as shown in the circuit diagram in Fig. 1(C), a plurality of parallel connection regions R are formed in which adjacent cells 2 are connected in parallel, and the parallel connection regions R are connected in series. According to the above configuration, the cathode connector 3a and the anode connector 3b that electrically connect the cells are disposed between the overlapping edge portions 2c of the cells and on the back side surface 2b of each cell 2, and nothing can be disposed except for finger electrodes (not shown) in the exposed area of ​​the front side surface 2a of each cell 2 where sunlight can reach, so that the light receiving surface of the cell can be disposed so as to receive the maximum amount of sunlight within the area occupied by the cell group. The configuration of the cathode connector 3a and the anode connector 3b may be a shape other than that shown in the example, and such a case also falls within the scope of the present embodiment.

[0026] The solar cell that can be used in this embodiment may be of any type, and may be a silicon-based solar cell such as a crystalline silicon solar cell that is commonly used in this field, a compound solar cell such as a GaAs cell, an organic solar cell, a multi-junction solar cell, a quantum dot solar cell, etc. As shown in Fig. 1(C), a bypass diode BPD may be connected in parallel to both ends of the cell group.

[0027] In addition, in the examples of Figures 1(A) to (C), two cells are connected in parallel in one parallel connection region, but the number of cells connected in one parallel connection region may be arbitrary. For example, as shown in Figure 1(D), three or more cells may be connected in parallel in one parallel connection region.

[0028] Each cell used in the cell group 1 according to the present embodiment does not necessarily have to be manufactured by dividing one large cell.

[0029] 1C and 1D, in the cell group 1 according to this embodiment, since a plurality of parallel connection regions R are connected in series, it is preferable that the light receiving area of ​​each parallel connection region R is adjusted so that the generated current of each parallel connection region R is equal and the generated current is not limited in any parallel connection region R when the light receiving surface is not shaded. When cells having the same light receiving area are used in the cell group, it is preferable that the number of cells connected in parallel to each parallel connection region R is equal.

[0030] Voltage-output characteristics of cell group 2 is a diagram showing the voltage-output characteristics obtained in a cell group consisting of 10 cells with the same light-receiving area arranged in a shingled structure (the voltage and output in the diagram were calculated by simulation). The diagram shows the output versus the generated voltage in each of the cases when there is no partial shadow (no shadow), when half of one cell is partially shaded, and when the entire area of ​​one cell is partially shaded, for the case where all cells in the shingled structure are connected in series (series-dotted line) as in the past, and the case where five pairs of regions in which two cells are connected in parallel are connected in series in the shingled structure according to the teaching of this embodiment (present example-solid line). Referring to the figure, when there is no partial shadow, the output obtained is the same in the case of connecting all the cells in series and in the case of this embodiment. However, when one cell is partially or entirely covered by partial shadow, when all the cells are connected in series, the generated current of the entire cell group is limited to the current of the cell with the smallest current, so the amount of decrease in the obtained output is large. When the entire area of ​​one cell is covered by partial shadow, no current flows through the entire cell group, and no power can be obtained from the cell group. On the other hand, in the case of this embodiment, even if one cell is partially or entirely covered by partial shadow, current flows through the cells connected in parallel to that cell, so the amount of decrease in output is relatively small. Even if the entire area of ​​one cell is covered by partial shadow, current flows through the entire cell group, so the state in which power can be obtained from the cell group is maintained. Thus, the cell group of this embodiment is advantageous in that it is expected to significantly reduce the chances of not being able to obtain any power when a solar panel device is mounted on the roof of a mobile body where partial shadows may change in various ways.

[0031] Connecting multiple cell groups The cell groups 1 of the present embodiment described above may be connected in parallel or in series (not shown) as illustrated in Fig. 3. When multiple cell groups 1 are connected in series, it is preferable to make the generated currents of each cell group 1 substantially equal to each other so that the current is not limited by the other cell groups 1, and when multiple cell groups 1 are connected in parallel, it is preferable to make the generated voltages of each cell group 1 substantially equal to each other so that each cell group 1 operates at a high-efficiency operating point. Therefore, when the cell groups are composed of cells having the same light-receiving area, it is preferable to make the number of cells the same in all cell groups, the number of cells connected in each parallel connection region the same, and the number of parallel connection regions connected in series the same.

[0032] As already mentioned, the cell group of the present embodiment is advantageously used in a solar panel mounted on a mobile object, but may also be used in other applications. This embodiment is also advantageously used in cases where the solar panel is placed in a location where the occupyable space is limited and where partial shading occurs depending on the time of day, or in the case of a portable panel.

[0033] The above description has been given in relation to the embodiment of the present invention, but it will be apparent to those skilled in the art that many modifications and changes can be easily made thereto, and that the present invention is not limited to the embodiment exemplified above, but can be applied to various devices without departing from the concept of the present invention.

Claims

1. A solar panel, a cell group in which a plurality of solar cells are arranged in one direction, the solar cells being arranged such that an edge portion of one front surface of adjacent solar cells overlaps an edge portion of a back surface of the other solar cell, and connection elements are arranged between the overlapping edge portions and on the back surfaces of the solar cells to electrically connect the plurality of solar cells to each other, In the cell group, a plurality of parallel connection regions are formed in which at least two solar cells are electrically connected in parallel, and the parallel connection regions are electrically connected in series, thereby forming a solar panel in which, among the plurality of cells arranged in one direction, there are portions in which adjacent cells are electrically connected in parallel and portions in which adjacent cells are electrically connected in series.

2. 2. The solar panel of claim 1, wherein in the portion of the cell group where adjacent parallel connection regions are electrically connected in series, a connection element electrically connecting two adjacent solar cells is disposed between the overlapping edge portions, and an insulating material layer is disposed on the back surface of each of the solar cells in the parallel connection region where an anode connection element connecting the anodes of the solar cells connected in parallel to each other is disposed, the anode connection element being disposed on the surface of the insulating material layer, and the overlapping edge portions of the solar cells connected in parallel to each other are insulated.

3. 3. A solar panel according to claim 1 or 2, wherein the light receiving area on the surface of each of the plurality of solar cells is equal to each other, and the number of solar cells connected in each of the plurality of parallel connection regions is equal to each other.

4. 4. A solar panel according to claim 3, comprising a plurality of said cell groups, the plurality of cell groups being electrically connected to each other in series or parallel, the number of solar cells included in each of the plurality of cell groups being equal to each other, and the number of solar cells connected to the parallel connection region being equal to each other.

Images