JP6541174B2 - Dye-sensitized solar cell and method of connecting dye-sensitized solar cell - Google Patents

Description

  The present invention is a dye-sensitized solar cell in which at least two or more cells are connected in series, and two or more of the cells are different from each other or different dyes, or the same dye and different shades. And a method of connecting a dye-sensitized solar cell.

  In recent years, the use of dye-sensitized solar cells has been promoted from the viewpoint of design. Examples of dye-sensitized solar cells are disclosed in Patent Document 1 and Patent Document 2.

JP 2014-093246 JP 2009-110796

  However, when using a plurality of cells of the same size but different dyes connected in series, the operating current (operating current Ipm at the maximum power point) generated varies depending on the dye, and a large power (or output) is obtained in the series connection. There was a problem that a loss would occur. Also, even if the cells are the same dye, if the density is different, the generated operating current (operating current Ipm at the maximum power point) varies among cells, and the same problem occurs.

  Therefore, an object of the present invention is to solve the above-mentioned problems, and to reduce the variation of the operating current at the maximum power point generated due to the difference of the dye or the density, thereby reducing the power (or output) loss. It is an object of the present invention to provide a dye-sensitized solar cell and a method for connecting a dye-sensitized solar cell.

  In order to achieve the above object, the present invention is configured as follows.

According to one aspect of the present invention, a dye-sensitized type in which at least two or more cells are connected in series, and two or more of the cells have different dyes or the same dyes and different shades of each other In the solar cell connection method,
Of the operating current of all cells (operating current Ipm at the maximum power point), the ratio of each cell is determined based on the cell with the lowest operating current,
Select a cell having a ratio that is equal to or greater than a threshold value;
The selected cell is divided into a plurality of divided cells, and the divided cells are connected in series.
Provided is a method of connecting a dye-sensitized solar cell.

  According to another aspect of the present invention, there is provided a dye-sensitized solar cell comprising the cell and the divided cell connected in series with each other by the method for connecting a dye-sensitized solar cell according to the above aspect. Do.

  According to the above aspect of the present invention, when the value of the ratio of the operating current of the cell determined based on the cell of the lowest operating current (the operating current Ipm at the maximum power point) is equal to or more than the threshold, the cell is selected The divided cells are divided into a plurality of divided cells, and the divided cells are connected in series. Such a configuration makes it possible to reduce variations in operating current caused by differences in dye or light and shade, and to reduce power (or output) loss.

FIG. 1 is a schematic cross-sectional side view of a dye-sensitized solar cell according to a first embodiment of the present invention. It is a schematic cross-section top view in the state which removed one part component in the dye-sensitized solar cell of FIG. It is a detailed cross-section side view before division | segmentation of one cell of the dye-sensitized solar cell concerning the said 1st Embodiment. It is a detailed cross-section top view before division | segmentation of one cell of the dye-sensitized solar cell concerning the said 1st Embodiment. It is a flowchart for demonstrating the process of division | segmentation of one cell of the dye-sensitized solar cell concerning the said 1st Embodiment. FIG. 2 is a schematic cross-sectional plan view of a layer lower than titanium oxide and a dye layer of one cell before division of the dye-sensitized solar cell according to the first embodiment. FIG. 7 is a schematic cross-sectional side view of the lower layer than the titanium oxide and dye layer of one cell of FIG. 6 before division. FIG. 5 is a schematic cross-sectional plan view of the upper layer above the catalyst electrode layer of one cell before division. FIG. 9 is a schematic cross-sectional side view of the upper layer above the catalyst electrode layer of one cell of FIG. 8 before division. It is a schematic cross-sectional top view of the lower layer than the catalyst electrode layer of one cell before division | segmentation. It is a schematic sectional side view of one cell before the division of FIG. It is a schematic cross-sectional top view of the titanium oxide of two division cells after division | segmentation of the dye-sensitized solar cell concerning 1st Embodiment, and a layer lower than a pigment layer of a pigment | dye layer. FIG. 13 is a schematic cross-sectional side view of the titanium oxide and dye layers of the two split cells of FIG. 12 after the split. It is a schematic cross-section top view over a catalyst electrode layer of two division cells after division. FIG. 15 is a schematic cross-sectional side view of the upper layer above the catalyst electrode layers of the two divided cells after the division of FIG. 14. It is a schematic cross-sectional top view of the lower layer than the catalyst electrode layer of two division cells after division. FIG. 17 is a schematic cross-sectional side view of the two split cells of FIG. 16 after the split. The example of the dye-sensitized solar cell concerning 2nd Embodiment WHEREIN: It is a schematic explanatory drawing which shows the state before division | segmentation. In the example of the dye-sensitized solar cell concerning the said 2nd Embodiment, it is a schematic explanatory drawing which shows the state after division | segmentation. It is a flowchart for demonstrating the process of another division | segmentation of one cell of the dye-sensitized solar cell concerning 3rd Embodiment. It is a graph for demonstrating the effect in the back and front of a division | segmentation of the dye-sensitized solar cell concerning the said 1st Embodiment etc.

  In the present specification and claims, the operating current means the operating current Ipm at the maximum power point.

(Findings of the Invention)
For example, it is generally known that the operating current at the maximum power point is different between the first cell and the second cell of the same area but different dyes. In such a case, when the first cell and the second cell are connected in series, the current of the first cell having a large operating current is limited to the current of the second cell due to the second cell having a small operating current. And there is a problem that power (or output) loss increases.

  Therefore, as a method of solving such a problem, focusing on the cell on the small operating current side, the area of the second cell of the small operating current is made larger than the area of the first cell, and the first cell It is conceivable to reduce the power (or output) loss by reducing the difference between the operating currents of the second cell and the second cell.

  However, in such a method, the area of a cell having a dye with a small operating current must always be large, while the area of a cell having a dye with a large operating current must always be small. Then, the size of the area of the cell is limited by the dye, and the degree of freedom in design is greatly limited.

  Therefore, the present inventors have found that, in two or more cells connected in series, operating current (operating current Ipm at the maximum power point) between a plurality of different dyes or a plurality of cells having the same dye and different shades. The operation of the divided cells divided into a plurality of divided cells by focusing on the cell having the larger operating current instead of focusing on the smaller cell of the cell. The value of the current is made close to the value of the operating current of the smaller one of the operating currents, and then connected in series. By configuring in this manner, the difference between the two is reduced, and power (or output) loss is reduced. That is, instead of devising the above-mentioned "cell with smaller operating current", by devising the "cell with larger operating current", the "pigment or the subject of the present invention" is produced. It is intended to achieve “a reduction in power (or output) loss” by reducing variations in operating current generated due to differences in density. By this solution, the size of the area is not limited by the dye or the shade, and the degree of freedom of design is not greatly restricted.

(Embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First Embodiment
(Constitution)
The dye-sensitized solar cell according to the first embodiment of the present invention is composed of at least one module having at least two or more cells. FIG. 1 shows a schematic cross-sectional side view of one module, and FIG. 2 shows a schematic cross-sectional plan view with some components of one module removed. FIG. 3 and FIG. 4 show a schematic cross-sectional side view of a dye-sensitized solar cell in which a plurality of modules are connected in series and a schematic cross-sectional plan view with some components removed. FIG. 5 is a flowchart for explaining the process of dividing one cell of the dye-sensitized solar cell according to the first embodiment. 6 and 7 show a cross-sectional plan view and a detailed cross-sectional side view of the titanium oxide and dye layer 12 of one cell before division. 8 and 9 show a cross-sectional plan view and a detailed cross-sectional side view of the upper layer above the catalyst electrode layer 14 of one cell before division. FIGS. 10 and 11 show a cross-sectional plan view of the lower layer of the catalyst electrode layer 14 of one cell before division and a detailed cross-sectional side view of one cell before division.

  The module 11 of the dye-sensitized solar cell is composed of at least two cells 1 and 2. More specific examples of the module 11 are shown in FIGS. 3 and 4. In FIG. 3 and FIG. 4, one module 11A is composed of four cells 1 and 2, and a plurality of modules 11A are shown connected to each other by a connection line 20. The dye-sensitized solar cell 21 is shown.

  Each module 11 is configured by connecting in series at least two or more cells 1 and 2 having different dyes or the same dyes and different shades of light.

  The module configuration of each of the cells 1 and 2 is a Z-type integrated structure. That is, at least one solar cell element 4 is produced on the first transparent substrate 3 of one sheet of insulating glass or the like, and each of the cells 1 and 2 is another sheet of insulating glass or the like The second transparent substrate 5 is further disposed on the solar cell element 4. Therefore, the cells 1 and 2 are respectively configured by the first transparent substrate 3, the solar cell elements 4 and the second transparent substrate 5.

  A conductive internal connection portion (interconnect) 6 is disposed between the adjacent cells 1 and 2, and a first electrode 7 on the first transparent substrate side of one cell 1 and a second transparent of the other cell 2. By electrically connecting the second electrode 8 on the substrate side, adjacent cells 1 and 2 are connected in series.

  Here, in the present specification, a cell is an energy converter that absorbs solar light energy and converts it directly into electricity, and means a single unit.

  Each solar cell element 4 has, as an example, a first transparent conductive layer 7 functioning as an example of the first electrode 7, a titanium oxide and dye layer 12, an electrolytic solution 13, and a catalyst in this order from the bottom to the top. An electrode layer 14 and a second transparent conductive layer 8 functioning as an example of a second electrode 8 are stacked. Of these layers, all around the sides of the three layers from the titanium oxide and dye layer 12 to the catalyst electrode layer 14 are sealed with an insulating sealing portion 15. In the sealing portion 15, current collectors 16a and 16b are disposed.

  The first transparent conductive layer 7 and the second transparent conductive layer 8 respectively extend in a lateral direction (cell direction relative to three layers from the titanium oxide and dye layer 12 to the catalyst electrode layer 14 sealed by the sealing portion 15 The connection terminals 7a and 8a are configured to project in a direction in which they are connected in series with each other and in the opposite direction. For example, in FIG. 1, the first transparent conductive layer 7 protrudes leftward to form the connection terminal portion 7a, and the second transparent conductive layer 8 protrudes rightward to form the connection terminal portion 8a. Then, the connection terminal portion 8 a of the second transparent conductive layer 8 of the first cell 1 and the connection terminal portion 7 a of the first transparent conductive layer 7 of the second cell 2 form the conductive internal connection portion (interconnect) 6. It is electrically connected via

Examples of the respective transparent conductive layers of the first transparent conductive layer 7 and the second transparent conductive layer 8 are formed of ITO, FTO, ATO, SnO ₂ , ZnO, or indium-zinc complex oxide (IZO), etc. can do.

Examples of titanium oxide (TiO ₂ ) and dye layer 12 include metal oxide semiconductors such as MgO, ZnO, WO ₃ , Nb ₂ O ₅ , TiSrO ₃ , or SnO ₂ as semiconductors other than TiO ₂ to be the photoelectrode. Be Further, examples of titanium oxide (TiO ₂ ) and the dye of the dye layer 12 include ruthenium metal complex dyes, metal complex dyes such as platinum, zinc and palladium, methine dyes, xanthene dyes, porphyrin dyes, azo dyes, Organic dyes such as coumarin dyes or polyene dyes can be mentioned. In addition, you may use these dyes in mixture of 2 or more types.

The electrolytic solution 13 is, for example, an electrolyte in which at least one reversibly substance system (oxidation-reduction system) causing an oxidation / reduction state change is dissolved. Examples of the redox system include, for example, halogens such as I ⁻ / I ₃ ⁻ and Br ⁻ / Br ₂ , quinones / hydroquinones, pseudo halogens such as SCN ⁻ / (SCN) ₂ , iron (II) ions / Although iron (III) ion or copper (I) ion / copper (II) ion is mentioned, it is not restricted to these. The electrolyte may be a liquid electrolyte, or a polymer electrolyte (gel electrolyte) containing this in a polymer substance, or a polymer solid electrolyte or an inorganic solid electrolyte. Specifically, as the electrolyte, a combination of iodine (I ₂ ) and metal iodide or organic iodide, a combination of bromine (Br ₂ ) and metal bromide or organic bromide, ferrocyanate / ferricyanate Or sulfur compounds such as ferrocene / ferricinium ions, viologen dyes, or hydroquinones / quinones. The cation of the metal compound is preferably Li, Na, K, Mg, Ca, Cs or the like, and the cation of the organic compound is tetraalkyl ammoniums, pyridiniums, or quaternary such as imidazoliums. Ammonium compounds are preferable, but not limited thereto, and two or more of them may be mixed and used. Among them, I ₂ and LiI, NaI, imidazolium iodide, or, preferably electrolytes that combines the ionic liquid such as quaternary ammonium iodide. In order to improve the open circuit voltage, various additives such as 4-tert-butylpyridine or carboxylic acid may be added to the electrolyte.

  The sealing portion 15 is made of, for example, a thermoplastic resin HIMIRAN (registered trademark) (Mitsui-Dupont Polychemicals Co., Ltd.), an epoxy thermosetting resin, an epoxy ultraviolet curing resin, or silicone rubber. It can be formed.

  The collecting wires 16a and 16b can be formed, for example, by selecting from metals including at least one of silver, copper, aluminum, tungsten, nickel, and chromium having low resistivity. As a method of forming the collecting wires 16a and 16b, a sputtering method, a vapor deposition method, a plating method, a screen printing method, or the like is used.

  The catalyst electrode layer 14 can use, for example, platinum, a carbon electrode, or a conductive polymer.

  Reference numeral 18 denotes a lead wire for electrically connecting the connection terminal 7a of the first transparent conductive layer 7 or the connection terminal 8a of the second transparent conductive layer 8 to an external terminal or element.

  In the first embodiment, at least two or more cells, for example, the first cell 1 and the second cell 2 have, as an example, the same structure but different dyes only, and have the same area and the same shape in plan view But it is not limited to this. For example, the first cell 1 and the second cell 2 may be configured to have the same structure but different shades only, and have the same area and the same shape in plan view. The shapes of the first cell 1 and the second cell 2 are, for example, square as an example, but the shape is not limited to this, and it is not limited thereto, and it may be rectangular, triangular, pentagonal, hexagonal, circular or elliptical. For example, any shape may be used. Of course, the shapes or areas of the first cell 1 and the second cell 2 may be different from each other.

(Split processing)
In the module 11 configured as described above, since the pigment is different between the first cell 1 and the second cell 2, variations occur in the power generation output capability, for example, the operating currents Ipm1 and Ipm2 at the maximum power point. Therefore, in the design stage of the dye-sensitized solar cell, the connection method of the dye-sensitized solar cell according to the first embodiment is as follows, in order to suppress the variation in the operating currents Ipm1 and Ipm2. The module 11 is reconfigured by dividing the cell with the larger operating current Ipm (or the power generation capacity) by an integer of 2 or more to form a divided cell. The following division processing will be described based on the flowchart of FIG.

  First, in step S1, the capability (or the value (Ipm) of the operating current) of the power generation output of each of all the cells 1 and 2 in the module 11 is obtained by measurement or the like. As an example of the method of acquiring the capacity of the power generation output of each of the cells 1 and 2, a solar simulator (for example, JIS C8912: solar simulator for crystalline solar cell measurement or JIS C 8933: amorphous solar cell measurement) for irradiating pseudo sunlight It can be measured using a solar simulator. Specific examples of measurement using a solar simulator will be described later.

  Next, in step S2, a cell having the lowest generated output (or operating current value Ipm) in the module 11 is selected as a reference cell, and the generating capacity (or operating current value Ipm) of the reference cell is, for example, 1 Suppose there is. Then, the ratio of how many times the power generation output (or the operating current value Ipm) of the other remaining cells is larger than the reference cell of which the power generation capacity (or the operating current value Ipm) of the reference cell is 1 ( Calculate the ratio of operating current). Here, as a reference for calculating the ratio of the operating current, the value of the lowest operating current among the operating currents of all the cells is used as an example, but the present invention is not limited thereto, and will be described in detail later. For example, the second lowest operating current value may be used as a reference.

  Next, in step S3, a cell in which a difference of 2 times or more occurs as a threshold is selected in the module 11 in the cell capacity of the power generation output. Here, the reason why the threshold value is set to be twice or more is because if it is at least two times or more, the effect associated with the division can be exhibited, and if it is at least two times or more, it can be divided by an integer of two or more is there. In the first embodiment, when there is no cell in which a difference of twice or more occurs in the module 11, it is determined that the reconfiguration of the module 11 is unnecessary, and the reconfiguration processing is ended. The threshold value is not limited to twice, and the fact that it may be twice or less will be described later.

  Next, in step S4, the selected cell is divided into a plurality of areas (divided cells), and the divided cells are redesigned to be connected in series. Here, for example, since the cell with the higher power generation capacity shown in FIGS. 3 and 4 is approximately twice as high, the area of the cell with the higher power generation capacity is divided into two, and FIGS. As shown in FIG. 5, the two divided cells 1-1 and 1-2 are redesigned to be connected in series at the connection portion 24.

  Note that if the cell with higher power generation capacity is about three times higher than the lower cell, it is divided into three, and if it is about four times higher, it is divided into four.

  Next, as a specific method of dividing the cell, for example, a method of dividing into two will be described below.

  12 and 13 show the titanium oxide and dye layers 12-1 and 12-2 of the two divided cells 1-1 and 1-2 after the division with respect to one cell before the division of FIGS. FIG. 5 shows a cross-sectional plan view and a detailed cross-sectional side view of a lower layer. FIG.14 and FIG.15 has shown the cross-sectional top view and detailed cross-sectional side view of the upper layer more than catalyst electrode layer 14 -1,14-2 of two division cell 1-1,1-2 after a division | segmentation. In FIG. 12 and FIG. 14, in order to clearly show the laser processing part 25, it is illustrated by a thick line. FIGS. 16 and 17 are cross-sectional plan views of lower layers of the catalyst electrode layers 14-1 and 14-2 of the two divided cells 1-1 and 1-2 after division and two divided cells 1-1 and 1-2 after division, respectively. Fig. 2 shows a detailed cross-sectional side view of 1-2.

  As shown in FIGS. 12 to 17, one cell 1 is divided into two in area to be divided into two divided cells 1-1 and 1-2, for example, divided into two at the center of FIG. More specifically, as shown by laser processing points 25 in FIG. 12 and FIG. 14, catalyst electrode layers 14-1 and 14-2 and titanium oxide and dye layers 12-1 and 12-2 are formed by laser processing. Divide each into two. The entire circumferences of the catalyst electrode layers 14-1 and 14-2 and the titanium oxide and dye layers 12-1 and 12-2 which are divided respectively are mutually sealed by sealing portions 15-1 and 15-2 and sealed. At the same time, rectangular current collectors 16a-1, 16a-2, 16b-1, 16b-2 are formed in the sealing portions 15-1, 15-2 in each of the divided cells 1-1, 1-2. Let's do it. In particular, in the central portion, sealing portions 15-1 and 15-2 are integrally formed between current collecting wires 16a-1 and 16a-2 adjacent to upper and lower and right and left and current collecting wires 16b-1 and 16b-2 adjacent to each other. It arrange | positions and the current collection conductors are mutually insulated. A connecting portion 24 is formed at one end, for example, the upper end of FIGS. 12, 14 and 16 which are plan views. The connection portion 24 is formed of a rectangular current collector 16b-1 disposed on the lower surface of the second transparent substrate 5 (current collector 16b-1 disposed on the upper right side of the central portion of the cross-sectional view of FIG. 17); The rectangular collector wire 16a-2 (collector wire 16a-2 disposed on the lower left side of the central portion in FIG. 17) disposed on the upper surface of the transparent substrate 3 is connected in series. The connection unit 24 is configured as follows. An overhanging portion 16b-3 is formed on the lower surface of the second transparent substrate 5 so as to protrude outward from the rectangular current collector wire 16b-1, and a second transparent member is formed at the tip of the overhanging portion 16b-3. A bent portion 16 b-4 which is bent and attached to the side surface of the substrate 5 is formed. In the vicinity of the bent portion 16b-4, an overhang portion 16a-3 projecting outward from the rectangular current collecting wire 16a-2 disposed on the upper surface of the first transparent substrate 3 is formed. In the connection portion 24, the end portion of the first transparent substrate 3 is arranged to be shifted from the second transparent substrate 5 so as to protrude. Although the bent portion 16b-4 and the overhang portion 16b-3 are different in phase by 90 degrees, since they are close to each other, if the solder portion 16e is formed so as to electrically contact both of them, electrical connection is made. It can be performed. As a result, the current collecting wire 16b-1 on the upper side of the divided cell 1-1 is a current collecting wire on the lower side of the divided cell 1-2 via the overhang portion 16b-3, the bent portion 16b-4, and the solder portion 16e. The divided cell 1-1 and the divided cell 1-2 can be connected in series by being connected to the extension 16a-3 of 16a-2.

  As a result, as shown in FIG. 16 and FIG. 17, one cell 1 is configured by two divided cells 1-1 and 1-2 connected in series. Each of the divided cells 1-1 and 1-2 is, in order from the lower first transparent substrate 3 side to the upper second transparent substrate 5 side, first transparent conductive layers 7-1 and 7-2, and Titanium oxide and pigment layers 12-1 and 12-2, electrolytic solutions 13-1 and 13-2, catalyst electrode layers 14-1 and 14-2, and second transparent conductive layers 8-1 and 8-2 It consists of These correspond to the first transparent conductive layer 7 before division, the titanium oxide and dye layer 12, the electrolytic solution 13, the catalyst electrode layer 14, and the second transparent conductive layer 8, respectively.

  According to the first embodiment, with reference to the lowest operating current of at least two or more cells, for example, the operating current (Ipm1) of the first cell 1 and the operating current (Ipm2) of the second cell 2, The ratio of the operating current of the cell is determined, and when the ratio is equal to or more than the threshold, the cell is divided into a plurality of divided cells, and the divided cells are connected in series. Such a configuration makes it possible to reduce variations in operating current caused by differences in dye or light and shade, and to reduce power (or output) loss.

  Therefore, in the first embodiment, as an example, divided cells 1 in which the cells 1 before division have the same area, the size and shape (outside) of each cell are constant, and the inside of each cell is divided. The size and shape (outer shape) of each cell as a whole are not changed before and after division only by the constitution 1-1 and 1-2. Therefore, it is not necessary to forcibly change the size or shape (outer shape) of the cell according to the power generation capacity, ignoring the designability, without any loss of the designability, and the design freedom is greatly limited. I have nothing to do.

Second Embodiment
As a connection method of the dye-sensitized solar cell according to the second embodiment of the present invention, an example applied to a case where three or more cells are connected in series will be described. Here, according to the cell, non-division, division into two, division into three, and division into four are performed.

  As a specific example of the module to be divided, the state before division is shown in FIG. 18 and the state after division is shown in FIG. Here, twelve cells 31 a to 31 l are connected in series by the lead wire 18. The numerical values in the rectangular frames of the cells 31a to 31l indicate the power generation capacity, and the higher the numerical value, the higher the power generation capacity.

As an example, if these are expressed as concentration,
1st cell 31a: second rich [power generation capacity = 3],
Second cell 31b: thinnest [power generation capacity = 1],
Third cell 31c: thinnest [power generation capacity = 1],
Fourth cell 31d: second rich [power generation capacity = 3],
Fifth cell 31e: third rich [power generation capacity = 2],
Sixth cell 31f: thinnest [power generation capacity = 1],
Seventh cell 31g: thinnest [power generation capacity = 1],
Eighth cell 31h: most dense [power generation capacity = 4.4],
9th cell 31i: third rich [power generation capacity = 2],
10th cell 31j: thinnest [power generation capacity = 1],
11th cell 31k: fourth rich [power generation capacity = 1.5],
12th cell 31 l: thinnest [power generation capacity = 1],
It becomes.

  In order to obtain the ratio, assuming that the power generation capacity as the reference is 1 as the lowest, the ratio of each cell is sequentially obtained based on the power generation capacity 1 below. Therefore, while the power generation capacity of the first cell 31a is 3, the power generation capacity of the second cell 31b is 1, and the ratio of the power generation capacities of the adjacent cells 31a and 31b is 3/1 = 3 and a difference of twice or more occurs in adjacent cells. Therefore, the first cell 31a having the higher power generation capacity of the adjacent cells 31a and 31b is the cell to be divided, and the number of divisions of the first cell 31a is, for example, 3/1 = 3 More specifically, it is divided into three divided cells 23 as shown in FIG.

  Similarly, while the power generation capacity of the third cell 31c is 1, the power generation capacity of the fourth cell 31d is 3, and the ratio of the power generation capacities of the adjacent cells 31c and 31d is 3/1. = 3, and a difference of twice or more occurs in the adjacent cells. Therefore, the fourth cell 31d having the higher power generation capacity among the adjacent cells 31c and 31d is the cell to be divided, and the number of divisions of the fourth cell 31d is, for example, 3/1 = 3 More specifically, it is divided into three divided cells 23 as shown in FIG. The power generation capacity of the fourth cell 31d is 3, and this is divided into three, so the power generation capacity of each divided cell 23 after division is 1.

  Also, while the power generation capacity of the fifth cell 31e is 2, the power generation capacity of the sixth cell 31f (or the division cell 23 of the fourth cell 31d) is 1, and adjacent to each other. The ratio of the power generation capacity of the cells 31e and 31f (or the divided cells 23 of the fourth cell 31d) is 2/1 = 2, and a difference of twice or more occurs in the adjacent cells. Therefore, the fifth cell 31e having the higher power generation capacity among the adjacent cells 31e and 31f (or the division cell 23 of the fourth cell 31d) is a cell to be divided, and as an example, the fifth cell 31e is a fifth cell. The division number of the third cell 31 e is divided into two divided cells 23 as shown in FIG. 19 according to 2/1 = 2. The power generation capacity of the fifth cell 31 e is two, and since this is divided into two, the power generation capacity of each divided cell 23 after division is one.

  The power generation capacity of the seventh cell 31g is 1, while the power generation capacity of the eighth cell 31h is 4.4, and the ratio of the power generation capacities of the adjacent cells 31g and 31h is 4. 4/1 = 4.4, and a difference of twice or more occurs in adjacent cells. Therefore, the eighth cell 31h having the higher power generation capacity of the adjacent cells 31g and 31h is the cell to be divided, and the number of divisions of the eighth cell 31h is, for example, 4.4 / 1. From = 4.4, as shown in FIG. 19, four divided cells 23 are to be divided. The power generation capacity of the eighth cell 31h is 4.4, and this is divided into four, so the power generation capacity of each divided cell 23 after division is 1.1.

  Further, while the power generation capacity of the ninth cell 31i is 2, the power generation capacity of the tenth cell 31j is 1, and the ratio of the power generation capacities of the adjacent cells 31i and 31j is 2/1 = 2 and a difference of twice or more occurs in adjacent cells. Therefore, the ninth cell 31i having the higher power generation capacity of the adjacent cells 31i and 31j is the cell to be divided, and the number of divisions of the ninth cell 31i is, for example, 2/1 = 2 More specifically, as shown in FIG. 19, it is divided into two divided cells 23. The power generation capacity of the ninth cell 31i is 2, and this is divided into two, so the power generation capacity of each divided cell 23 after division is 1.

  On the other hand, in combinations of adjacent cells other than those described above, since the ratio of power generation capacity is less than 2, it is not a division target. For example, while the power generation capacity of the second cell 31b is 1, the power generation capacity of the third cell 31c is also 1, and the ratio of the power generation capacities of the adjacent cells 31b and 31c is 1/1 = 1 1, and a difference of 2 times or more does not occur between adjacent cells, and is not a division target. Also, while the power generation capacity of the divided cell 23 of the fourth cell 31 d is 1, the power generation capacity of the divided cell 23 of the fifth cell 31 e is also 1, and the power generation capacity of the adjacent divided cell 23 is The ratio of {fraction (1/1)} is 1 = 1, and a difference of twice or more does not occur between adjacent divided cells 23 and is not a division target. Further, while the power generation capacity of the divided cell 23 of the eighth cell 31 h is 1.1, the power generation capacity of the divided cell 23 of the ninth cell 31 i is 1, and the power generation capacity of the adjacent divided cell 23 is The ratio of the power generation capacity is 1.1 / 1 = 1.1, and a difference of twice or more does not occur between the adjacent divided cells 23 and is not a division target. Further, the power generation capacity of the eleventh cell 31k is 1.5, whereas the power generation capacity of the tenth or twelfth cell 31j or 31l is 1, and the ratio of the power generation capacities of the adjacent cells Is 1.5 / 1 = 1.5, and a difference of 2 times or more does not occur between adjacent cells, and is not a division target.

  Therefore, as shown in FIG. 19, in the module after division processing, the ratio of the power generation capacity between adjacent cells or adjacent division cells 23 is less than twice, and the operating current Ipm1,1 generated due to the difference in dye or concentration ..., Ipm12 variation can be reduced to reduce power (or output) loss.

  The ratio is determined in order of serial connection, but it is not necessary to determine in order. For example, after determining the power generation capacity as a reference, the ratios of all cells are calculated simultaneously and determined It goes without saying that it is possible to do so.

Third Embodiment
Next, in the connection method of the dye-sensitized solar cell according to the third embodiment of the present invention, it will be described that a case where the threshold value is less than 2 can be considered.

The above-mentioned step S3 is the ratio of the operating current I ₁ (for example, operating current Ipm1) of the first cell to the operating current I ₂ (for example, operating current Ipm2) of the second cell among the two cells in one module. When the value is equal to or greater than the threshold, it means that the cell is divided. The threshold is doubled in step S3 of the previous embodiment, but is not limited to this, and may be, for example, 1.33. This will be described below.

As described in step S3, determination of whether or not divided into a plurality of divided cells 1-1 and 1-2, the operation current I ₂ of the operating current I ₁ and the second cell of the first cell It is judged whether the value of the ratio is equal to or more than a threshold. Instead of determining whether or not to divide using such a threshold, it may be determined whether to divide in accordance with the following procedure as shown in FIG.

That is, the operating current I ₁ of the first cell of the operating current I ₂ of the second cell, when the operating current I ₁ of the first cell is lower than the operating current I ₂ of the second cell, the entire operating current , And the operating current I ₁ of the first cell. Here, assuming that both voltages are V, the total output P of the first cell and the second cell in the undivided state is P = {2 · I ₁ · V} (see FIG. 20). See step S11).

Next, the operating current (I ₂ / n) of one divided cell when dividing the second cell with higher operating current into n divided cells is compared with the operating current I ₁ of the first cell. The lower operating current is I _d . At this time, the total output P ′ of the first cell and all the divided cells of the second cell is P ′ = {(n + 1) · _Id · V} (see step S12 in FIG. 20).

At this time, if the total output P ′ = {(n + 1) · I _d · V} after division is larger than the total output P = {2 · I ₁ · V} before division (P <P ′), This is the case where the division becomes effective (see step S13 and step S14 in FIG. 20). Conversely, if the total output before division P = {2 · I ₁ · V} is greater than or equal to the total output after division P ′ = {(n + 1) · I _d · V} (P ≧ P ′), , Division is not effective (see step S12 and step S15 in FIG. 20).

Specifically, for example, if the ratio of the operating current I ₁ of the first cell to the operating current I ₂ of the second cell is I ₂ / I ₁ = 1.8 and the second cell is divided into two by n = 2 _assuming, when the _{(I 2/2) <I} 1,
The total output P before division is
P = I ₁ · V + I ₁ · V
= 2 · I ₁ · V
It is.

The total output P 'after division is
_{P '= 2 · (I 2} /2 · V) + I 2/2 · V
_{= 3 · (I 2/2} ) V
_{= 3 · (1.8 · I 1} /2) V
= 2.7 · I ₁ · V
It is.

Therefore, P <P ′, and even if the ratio I ₂ / I ₁ is 2 or less, the total output may be higher if divided, and it is understood that the division is effective.

  This will be described below as a general expression.

First, if I ₂ > I ₁ and the ratio is I ₂ / I ₁ = m and the number of divisions is n, then
The total output P before division is
P = 2 · I ₁ · V
It is.

The total output P 'after division is
P '= (n + 1) (I ₂ / n · V)
= (N + 1) (m / n · I ₁ · V)
It is. Therefore, in order to improve the total output by division, it is necessary to satisfy P <P ′.
{2 · I ₁ · V} <{(n + 1) (m / n · I ₁ · V)}
∴ m> {2 n / (n + 1)}
When the number of divisions n satisfying this equation is determined, the total output is higher in the case of division than in the case of no division. For this reason, this equation serves as a criterion (threshold) for determining whether or not to divide. In other words, a cell having a ratio larger than the threshold value 2n / (n + 1) may be selected, the selected cell may be divided into n divided cells, and the divided cells may be connected in series.

  Hereinafter, when the division number n and the threshold value {2n / (n + 1)} are illustrated based on this equation, Table 1 below is obtained.

  Therefore, in the description of step S3, although the threshold value is set to 2 or more, it is understood from Table 1 that the threshold value may be set to 1.33 or more instead of 2 or more. In other words, the method of connecting the dye-sensitized solar cells according to the third embodiment is the same as the method of connecting the dye-sensitized solar cells according to the previous embodiment with the threshold value set to 1.33 times. It is meant to be the result. Therefore, also in the third embodiment, the same function and effect as those of the previous embodiment can be obtained.

  In addition, although the ratio is calculated | required by adjacent cells, it is not restricted to this. That is, instead of determining the ratio between two adjacent cells, the ratio may be determined between any two cells among a plurality of cells in one module. The ratio of the reference cell to the other cells may be determined in order, with one of the two cells as the reference cell.

  In addition, although the power generation capacity of the cell, which is the basis for determining the ratio, is the lowest power generation capacity, it is not limited to this. For example, in the case where at least two or more cells are configured by three cells of a first cell, a second cell, and a third cell, any one of the three cells excluding the cell with the highest operating current The operating current of the cell (eg, the cell with the second largest operating current or the cell with the lowest operating current) may be used as the reference operating current. Then, the ratio between the reference operating current and the operating current of the cells other than the cells applied to the reference operating current is determined, and when the value of the determined ratio is equal to or greater than the threshold, the other than the cells applied to the reference operating current The cell may be divided into a plurality of divided cells, and the divided cells may be connected in series.

  Hereinafter, an example in which the ratio is determined as well as adjacent cells and an example in which the ratio is determined on the basis of cells other than the cell with the lowest power generation capacity will be described.

  Here, consider, as an example, a dye-sensitized solar cell in which eight cells are connected in series.

  The output (generation capacity) of each cell is as shown in Table 2. For the sake of simplicity, it is not an actual numerical value but represented by the output ratio of each cell to the output of the first cell.

  In such a case, when the ratios between adjacent cells are calculated, they all become 1.3 times, and become less than the above-described threshold value of 1.33 times. When this threshold value is used, division is It is considered unnecessary.

  However, the ratio of the power generation capacity 1.0 of the first cell to the power generation capacity 6.3 of the eighth cell is 6.3 times, which is 1.33 times or more which is the above-mentioned threshold, and division is more I understand that it is good. Thus, instead of comparing adjacent cells with each other to determine the ratio, among all the cells of the dye-sensitized solar cell, for example, the ratio of the other cells is determined based on the cell with the lowest power generation capacity. In some cases, it may be desirable to consider the possibility of division. As an example thereof, a column of “ratio to first cell” is provided in Table 2 to obtain each ratio. Then, it is understood that it is better to divide all of the third to eighth cells.

  In addition, although the ratio is determined based on the cell with the lowest power generation capacity (the first cell in this example), the following description will be made of the fact that it is not limited to this. For example, on the basis of the third cell, the ratio of the other cells is determined, and the possibility of division is examined. As an example, in Table 2, a column of “ratio to third cell” is provided to calculate each ratio. Then, it is understood that it is better to divide all of the fifth to eighth cells.

Fourth Embodiment
Next, as a method of connecting the dye-sensitized solar cells according to the fourth embodiment of the present invention, a method of determining an optimal number of divisions will be described. The previous embodiment exemplifies a case where it is better to divide rather than not divide. However, in this case, the number of divisions may be two or more, and the optimal number of divisions is not pursued. In the fourth embodiment, by explaining a method of obtaining the optimum number of divisions, it is possible to obtain an optimum method of connecting dye-sensitized solar cells.

  The above-mentioned threshold equation is a criterion for determining whether the total output can be increased by dividing rather than not dividing, and is different from the determination of the optimal number of divisions.

As an example, the optimal number of divisions can be considered as follows. However, the condition branches depending on the magnitude relationship between the operating current I ₂ / n of the _second cell and the operating current I ₁ of the first cell.

(1) When the operating current I ₂ / n of the second cell after division is greater than or equal to the operating current I ₁ of the first cell (I ₂ / n I I ₁ ), the entire operating current is the operating current of the first cell I is limited to ₁

In this case, the output difference ΔP between the total output P ′ after division and the total output P before division is
ΔP = P'-P
= {(N + 1) · I ₁ · V}-{2 · I ₁ · V}
= {(N-1) · I ₁ · V}
It is.

(2) When the operating current I ₂ / n of the second cell after division is lower than the operating current I ₁ of the first cell (I ₂ / n <I ₁ ), the entire operating current is the second after division It is limited by the operating current I ₂ / n of the cell.

In this case, the output difference ΔP between the total output P ′ after division and the total output P before division is
ΔP = P'-P
= {(N + 1) (I ₂ / n) V}-{2 · I ₁ · V}
= {(N + 1) m / n-2} I ₁ V
It is.

  If the ratio m is known, the value (integer) of the division number n when the output difference ΔP takes the maximum is the optimum division number. In the following, as an example, when the value of the ratio m is 2, 2.2, 2.4, etc., the number of divisions is substituted in the order of n = 2, 3, 4,. If the value (integer) of the division number n when the output difference ΔP takes the maximum is determined, the following Table 3 is obtained.

  Of course, this is a method of determining the optimal number of divisions as an example. For example, when the ratio m = 2.6, the number of divisions n = 3 is optimum, but when the number of divisions n = 2, the effect of division is It does not mean that there is no. In other words, even if the division number n = 2, the total output is expected to increase compared to the case where the division is not performed, which is effective as the present invention.

According to the fourth embodiment, the optimum number of divisions can be determined according to the ratio of (the operation current I ₂ of the target cell for division determination judgment / the operation current I ₁ of the reference cell) Can reduce the variation in operating current caused by the difference in power, and can reduce power (or output) loss. As a result, the method of connecting the dye-sensitized solar cells can be implemented more efficiently. When the division is performed with the optimum number of divisions in this manner, the power (or output) loss can be minimized.

  As described in the first to fourth embodiments, the number of cells to be divided among a plurality of cells constituting one module, depending on which cell is used to obtain a ratio and to compare with a threshold value. Will change. Finally, it is preferable to select and connect the number of divisions that is considered optimal for the product in terms of the cost or labor of product design or manufacture.

(Test to demonstrate the effect of split processing)
A test was conducted to explain the effect of the division process of the above-described embodiment.

  In the test, 5 cells were used for each condition, and a solar simulator for measuring a crystal solar cell defined in JIS C 8912: 2011 was used. Each of the five cells used in the test was a square of the same size, and a total of five cells of a green cell, a red cell, a green cell, a red cell, and a green cell were connected in series. . Let each of these cells be a pre-division module including cells before division. A total of five cells of the same configuration as the cells before division are prepared, and among them, two red cells are divided vertically into two and connected in series, green cells, red divided cells , A red divided cell, a green cell, a red divided cell, a red divided cell, and a green cell, for a total of seven cells in series. Let these cells be post-division modules including the post-division cells. The maximum output was measured seven times for each of the modules before and after this division.

  Specifically, using the solar simulator for crystal-based solar cell measurement defined in JIS C 8912: 2011, the power generation capacity of each cell was measured and evaluated for the module before division and the module after division. . This simulator is a solar simulator using a xenon lamp, and the air mass (Air Mass) as a certain common measurement condition (Standard Test Condition (STC)) when representing the nominal maximum output of the solar panel ) (Amount of air until sunlight reaches the ground) Irradiate each cell for 2 to 3 minutes under the conditions of 1.5, 25 ° C, 1 kW / square meter, and change the voltage within the predetermined range The change in current was measured. Then, based on the measurement result, a curve graph of voltage and current is determined, and further, the maximum output power is obtained at the point where the largest square can be obtained in the region surrounded by the vertical axis, horizontal axis and curve graph of the curve graph. It calculated | required as point Pmax. This maximum output point Pmax is determined for each measurement, and is shown by a bar graph in FIG. The vertical axis of FIG. 21 is the maximum output Pmax, and the horizontal axis is the cell before division and the cell after division.

  From FIG. 21, the maximum output Pmax is improved by about 30% overall in the cells after division with respect to the cells before division. This is because the power (or output) loss due to power generation is reduced by dividing the cells in such a way as to match the power generation amount of the adjacent cells, and the cells after division are more efficient power generation as solar cells. Know that you are

  The present invention is not limited to the above embodiment, and can be implemented in various other aspects.

  In addition, the effect which each has can be show | played by combining suitably the arbitrary embodiment or modification of said various embodiment or modification. Further, a combination of the embodiments or a combination of the embodiments or a combination of the embodiments and the embodiments is possible, and a combination of the features in different embodiments or the embodiments is also possible.

  The connection method of the dye-sensitized solar cell and the dye-sensitized solar cell according to the present invention can reduce the variation of the operating current generated due to the difference of the dye and can reduce the power (or output) loss. It is useful, for example, when designing the configuration of a dye-sensitized solar cell.

  DESCRIPTION OF SYMBOLS 1 ... 1st cell, 1-1, 1-2 ... division | segmentation cell, 2 ... 2nd cell, 3 ... 1st transparent substrate, 4 ... solar cell element, 5 ... 2nd transparent substrate, 6 ... internal connection part (interconnect (interconnect) 7) first electrode (first transparent conductive layer) 7a connection terminal portion 7-1, 7-2 split first electrode (split first transparent conductive layer) 8 second electrode (second Transparent conductive layer), 8a: connection terminal portion, 8-1, 8-2: split second electrode (split second transparent conductive layer), 11: module, 12, 12a: titanium oxide and dye layer, 12-1, 12-2 ... divided titanium oxide and pigment layer, 13, 13a ... electrolyte, 13 -1, 13-2 ... divided electrolyte, 14, 14 ... ... catalyst electrode layer, 14-1, 14-2 ... divided catalyst electrode layer , 15: Sealed portion, 15-1, 15-2: Divided sealed portion, 16a, 16b: Collected wire, 16a-1, 16a-2, 16b- , 16b-2 ... divided collecting wire, 16a-3, 16b-3 ... overhanging portion, 16b-4 ... bent portion, 16e ... solder portion, 18 ... lead wire, 20 ... connection wire, 21 ... dye-sensitized type Solar cell, 23: division cell, 24: connection portion, 25: laser processing point, 31a to 31l: cell.

Claims (7)

In a method of connecting dye-sensitized solar cells, at least two or more cells are connected in series, and two or more of the cells have different dyes or the same dye and different shades of light,
Of the operating currents of all the cells, the ratio of each cell is determined based on the cell with the lowest operating current (S2),
Select a cell having a ratio that is equal to or greater than a threshold (S3);
The selected cell is divided into a plurality of divided cells having the same area, and the divided cells are connected in series (S4).
Method of connecting dye-sensitized solar cells. When selecting a cell having a ratio equal to or greater than the threshold, the threshold is 2.
The connection method of the dye-sensitized solar cell according to claim 1. When selecting a cell having a ratio equal to or higher than the threshold (S3), select a cell having a ratio larger than the threshold 2n / (n + 1);
When the divided cells are connected in series (S4), the selected cell is divided into n divided cells, and the divided cells are connected in series.
The connection method of the dye-sensitized solar cell according to claim 1. When the divided cells are connected in series (S4), the selected cell is divided into n divided cells, and the divided cells are connected in series:
When the total output P 'of the n divided cells after division is larger than the output P of the cell before division for the selected cell, the integer n is the integer when the output difference ΔP between the cells before and after the division is maximum Split as
The connection method of the dye-sensitized solar cell according to claim 3. When the ratio to each cell is determined based on the cell with the lowest operating current (S2), the cell with the lowest second operating current from the lowest operating current is used as the reference, instead of the cell with the lowest operating current. Find the ratio to each cell,
The connection method of the dye-sensitized solar cell according to claim 1. When the divided cells are connected in series (S4), the cells have the same area,
The connection method of the dye-sensitized solar cell according to any one of claims 1 to 5. Wherein when a division between cells connected in series (S4), a same shape,
The connection method of the dye-sensitized solar cell according to any one of claims 1 to 6.

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