JP2016171175A - Dye-sensitization solar cell and connection method of dye-sensitization solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dye-sensitization solar cell in which power (or output) loss can be reduced, by reducing variations in the working current occurring at the maximum power point due to difference of dye or concentration, and to provide a connection method of the dye-sensitization solar cells.SOLUTION: In a connection method of dye-sensitization solar cells where more than one cells are connected in series, and two or more cells 1, 2 thereof have dyes different from each other, or the same dye of different shade, the ratio of each cell is obtained with reference to a cell of the lowest working current, out of the working currents of all cells. Such cells 1 that the ratio thus obtained is equal to or larger than a threshold are selected, and divided into division cells 1-1, 1-2 of a plurality of cells, before being connected in series.SELECTED DRAWING: Figure 5

Description

  The present invention relates to 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 composed of different dyes or the same dye and different shades. And a method for connecting a dye-sensitized solar cell.

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

JP 2014-093246 A JP 2009-110696 A

  However, when a plurality of cells of the same size and different dyes are connected in series, the operating current generated (operating current Ipm at the maximum power point) varies depending on the dye, and a large amount of power (or output when connected in series) ) There was a problem of loss. In addition, even when a plurality of cells are the same pigment, when the shades are different, the generated operating current (the operating current Ipm at the maximum power point) varies among the cells, and the same problem occurs.

  Accordingly, an object of the present invention is to solve the above-mentioned problem, and to reduce power (or output) loss by reducing the variation of the operating current at the maximum power point caused by the difference in pigment or shading. Another object of the present invention is 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, 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. In the method of connecting solar cells,
Of the operating currents of all the cells (the operating current Ipm at the maximum power point), the ratio of each cell is obtained based on the cell having the lowest operating current,
Select cells having a ratio where the determined ratio is greater than or equal to a threshold;
Dividing the selected cell into a plurality of divided cells and connecting the divided cells in series;
A method for connecting a dye-sensitized solar cell is provided.

  According to another aspect of the present invention, there is provided a dye-sensitized solar cell configured by connecting the cells and the divided cells to each other in series by the method for connecting the dye-sensitized solar cells described in the above aspect. To do.

  According to the above aspect of the present invention, when the value of the cell operating current ratio obtained with reference to the cell having the lowest operating current (operating current Ipm at the maximum power point) is equal to or greater 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. With such a configuration, variation in operating current caused by a difference in pigment or light and shade can be reduced, and power (or output) loss can be reduced.

1 is a schematic cross-sectional side view of a dye-sensitized solar cell according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional plan view of the dye-sensitized solar cell of FIG. 1 with some components removed. It is a detailed cross-sectional side view before the division | segmentation of one cell of the dye-sensitized solar cell concerning the said 1st Embodiment. It is a detailed cross-sectional top view before the 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 the division | segmentation of one cell of the dye-sensitized solar cell concerning the said 1st Embodiment. FIG. 3 is a schematic cross-sectional plan view of a lower layer 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 layer below the titanium oxide and dye layer of one cell before division in FIG. 6. It is a schematic sectional plan view of a layer above the catalyst electrode layer of one cell before division. FIG. 9 is a schematic cross-sectional side view of the layer above the catalyst electrode layer of one cell before division in FIG. 8. It is a schematic sectional plan view of a layer lower than the catalyst electrode layer of one cell before division. It is a schematic sectional side view of one cell before the division | segmentation of FIG. FIG. 3 is a schematic cross-sectional plan view below the titanium oxide and the dye layer of two divided cells after the division of the dye-sensitized solar cell according to the first embodiment. FIG. 13 is a schematic cross-sectional side view of the layer below the titanium oxide and the dye layer in the two divided cells after the division in FIG. 12. It is a schematic sectional plan view of a layer above the catalyst electrode layer of two divided cells after division. FIG. 15 is a schematic cross-sectional side view of the layer above the catalyst electrode layer of the two divided cells after the division in FIG. 14. It is a general | schematic cross-sectional top view of the lower layer from the catalyst electrode layer of two division cells after a division | segmentation. FIG. 17 is a schematic sectional side view of two divided cells after the division of FIG. 16. In the example of the dye-sensitized solar cell concerning 2nd Embodiment, it is a schematic explanatory drawing which shows the state before division | segmentation. It is a schematic explanatory drawing which shows the state after a division | segmentation in the example of the dye-sensitized solar cell concerning the said 2nd Embodiment. 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 before and behind the division | segmentation of the dye-sensitized solar cell concerning the said 1st Embodiment.

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

(Knowledge of the present 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 different dyes having the same area. 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 rate-limited to the current of the second cell due to the second cell having a small operating current. As a result, power (or output) loss increases.

  Therefore, as one method for solving such a problem, paying attention to a cell on the small operating current side, the area of the second cell having a small operating current is made larger than the area of the first cell, so that the first cell It is conceivable to reduce the power (or output) loss by reducing the difference in operating current between the first cell and the second cell.

  However, in such a method, it is necessary to always increase the area of a cell having a dye having a small operating current, while it is necessary to always reduce the area of a cell having a dye having a large operating current. Then, the size of the cell area is limited by the pigment, and the degree of freedom in design is greatly limited.

  Therefore, the inventors of the present invention have an operation current (operation current Ipm at the maximum power point) between a plurality of cells having two or more cells connected in series and having different dyes or the same dye and different shades. Instead of focusing on the smaller cell, focus on the cell with the larger operating current, and divide the cell with the larger operating current into a plurality of divided cells. The current values are made closer to the operating current value of the cell with the smaller operating current, and then connected in series. By configuring in this way, the difference between the two is reduced, and the power (or output) loss is reduced. That is, instead of devising the above-mentioned “cell having a smaller operating current”, devising the “cell having a larger operating current”, the problem of the present invention is “dye or dye”. This is achieved by reducing the variation in the operating current generated due to the difference in density and reducing the power (or output) loss. According to this solution, the size of the area is not limited by the pigment or light and shade, and the degree of freedom of design is not greatly limited.

(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 includes at least one module having at least two cells. FIG. 1 shows a schematic cross-sectional side view of one module, and FIG. 2 shows a schematic cross-sectional plan view in a state where some components of one module are removed. 3 and 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 a 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 below 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 layer above the catalyst electrode layer 14 of one cell before division. 10 and 11 show a sectional plan view below the catalyst electrode layer 14 of one cell before division and a detailed 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, one module 11 </ b> A includes four cells 1 and 2, and a dye-sensitized solar cell 21 in which a plurality of modules 11 </ b> A are connected to each other via a connection line 20 is illustrated.

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

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

  Between the adjacent cells 1 and 2, a conductive internal connection (interconnect) 6 is arranged, and the first electrode 7 on the first transparent substrate side of one cell 1 and the 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 this specification, a cell is an energy converter that absorbs solar light energy and converts it directly into electricity, and means a single constituent unit.

  As an example, each solar cell element 4 includes, from bottom to top, in order, a first transparent conductive layer 7 that functions as an example of the first electrode 7, a titanium oxide and dye layer 12, an electric field solution 13, and a catalyst. The electrode layer 14 and the second transparent conductive layer 8 that functions as an example of the second electrode 8 are laminated. Among these layers, the periphery of all of the side portions of the three layers from the titanium oxide and dye layer 12 to the catalyst electrode layer 14 is sealed with an insulating sealing portion 15. In the sealing part 15, current collecting wires 16 a and 16 b are arranged.

  The first transparent conductive layer 7 and the second transparent conductive layer 8 are respectively in the lateral direction (cells) with respect to the three layers from the titanium oxide and dye layer 12 to the catalyst electrode layer 14 sealed by the sealing portion 15. The connecting terminal portions 7a and 8a are configured so as to protrude in the opposite direction). For example, in FIG. 1, the 1st transparent conductive layer 7 protrudes leftward, and comprises the connection terminal part 7a, and the 2nd transparent conductive layer 8 protrudes rightward, and comprises the connection terminal part 8a. 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 a conductive internal connection portion (interconnect) 6. Is electrically connected.

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

Examples of the titanium oxide (TiO ₂ ) and the dye layer 12 include a metal oxide semiconductor such as MgO, ZnO, WO ₃ , Nb ₂ O ₅ , TiSrO ₃ , or SnO ₂ as a semiconductor other than TiO _{2 serving} as a photoelectrode. It is done. Examples of the 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, Examples thereof include organic dyes such as coumarin dyes and polyene dyes. In addition, you may use these pigments in mixture of 2 or more types.

The electrolysis solution 13 is, for example, one in which at least one substance system (oxidation reduction system) that reversibly changes the state of oxidation / reduction is dissolved in an electrolyte. Examples of the redox system include, for example, halogens such as I ⁻ / I ₃ ⁻ and Br ⁻ / Br ₂ , pseudohalogens such as quinone / hydroquinone and SCN ⁻ / (SCN) ₂ , iron (II) ions / Examples include, but are not limited to, iron (III) ions or copper (I) ions / copper (II) ions. The electrolyte may be a liquid electrolyte, a polymer electrolyte (gel electrolyte) containing this in a polymer substance, a polymer solid electrolyte, or an inorganic solid electrolyte. Specifically, examples of the electrolyte include 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 a sulfur compound such as ferrocene / ferricinium ion, a viologen dye, or hydroquinone / quinone. As the cation of the metal compound, Li, Na, K, Mg, Ca, Cs, or the like is preferable. Ammonium compounds are preferred, but are not limited to these, and two or more of these may be used in combination. Among them, an electrolyte in which I ₂ and an ionic liquid such as LiI, NaI, imidazolium iodide, or quaternary ammonium iodide are combined is preferable. For the purpose of improving the open circuit voltage, various additives such as 4-tert-butylpyridine or carboxylic acid may be added to the electrolyte.

  Each of the sealing portions 15 is made of, for example, Himiran (registered trademark) (manufactured by Mitsui DuPont Polychemical Co., Ltd.), an epoxy thermosetting resin, an epoxy UV curable resin, or silicon rubber, which is a thermoplastic resin. Can be formed.

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

  For example, platinum, a carbon electrode, or a conductive polymer can be used for the catalyst electrode layer 14.

  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 and 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, for example, the same structure, only different dyes, and the same area and the same shape in plan view. However, it is not limited to this. For example, the first cell 1 and the second cell 2 may have the same structure, differ only in shading, and may have the same area and the same shape when viewed in plan. In addition, the shapes of the first cell 1 and the second cell 2 are, for example, squares, but are not limited thereto, but are not limited thereto, but are rectangular, triangular, pentagonal, hexagonal, circular, or elliptical. Any shape can be used. Of course, the shape or area of the first cell 1 and the second cell 2 may be different from each other.

(Division processing)
In the module 11 configured as described above, since the pigments are different between the first cell 1 and the second cell 2, the power generation output capability, for example, the operating currents Ipm1 and Ipm2 at the maximum power point varies. Therefore, in order to suppress variations in the operating currents Ipm1 and Ipm2 at the design stage of the dye-sensitized solar cell, as a connecting method of the dye-sensitized solar cell according to the first embodiment, The reconfiguration process of the module 11 is performed by dividing the cell having the larger operating current Ipm (or the power generation output capability) by an integer of 2 or more into divided cells. The following division processing will be described based on the flowchart of FIG.

  First, in step S1, the capacity (or operating current value (Ipm)) of each of the power generation outputs of all the cells 1 and 2 in the module 11 is acquired by measurement or the like. As an example of a method for acquiring the power generation output capability of each of the cells 1 and 2, a solar simulator for irradiating pseudo-sunlight (for example, JIS C8912: solar simulator for measuring a crystalline solar cell or JIS C8933: for measuring an amorphous solar cell) 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 power generation output (or operating current value Ipm) in the module 11 is selected as a reference cell, and the power generation capacity (or operating current value Ipm) of the reference cell is set to 1, for example. Assume that there is. The ratio of how many times the power generation output (or operation current value Ipm) of the remaining cells is larger than the reference cell whose power generation capacity (or operation current value Ipm) is 1. The value of the ratio of the operating current is calculated. 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. For example, the second lowest operating current value may be used as a reference.

  Next, in step S3, a cell having a difference of two times or more as a threshold value is selected in the module 11 in the power generation output cell capability. Here, the threshold is set to 2 times or more because if it is at least 2 times or more, the effect of the division can be exhibited, and if it is at least 2 times or more, it can be divided by an integer of 2 or more. is there. In the first embodiment, if there is no cell in the module 11 that has a difference of twice or more, it is determined that the reconfiguration of the module 11 is unnecessary, and the reconfiguration process is terminated. Note that the threshold value is not limited to twice, and may be equal to or less than twice.

  Next, in step S4, the selected cell is divided into a plurality of regions (divided cells) and redesigned so that the divided cells are connected in series. Here, for example, the cell with the higher power generation output capability in FIGS. 3 and 4 is about twice as high, so the area of the cell with the higher power generation output capability is divided into two, and FIGS. As shown in FIG. 2, the two divided cells 1-1 and 1-2 are redesigned so as to be connected in series at the connection unit 24.

  If the cell having the higher power generation output capacity is about three times higher than the lower cell, the cell is divided into three, and if it is about four times higher, the cell is divided into four.

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

  6 and FIG. 11, FIGS. 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. A cross-sectional plan view and a detailed cross-sectional side view of a lower layer are shown. 14 and 15 show a cross-sectional plan view and a detailed cross-sectional side view of the layers above the catalyst electrode layers 14-1 and 14-2 of the two divided cells 1-1 and 1-2 after the division. In FIG. 12 and FIG. 14, the laser processing location 25 is shown by a thick line in order to clearly show it. 16 and 17 are a cross-sectional plan view below the catalyst electrode layers 14-1 and 14-2 of the two divided cells 1-1 and 1-2 after the division, and the two divided cells 1-1 and 1-2 after the division. 1-2 shows a detailed cross-sectional side view.

  As shown in FIGS. 12 to 17, one cell 1 is divided into two areas to be divided into two divided cells 1-1 and 1-2, for example, at the center of FIG. 16. More specifically, in FIGS. 12 and 14, as shown by a laser processing location 25, the catalyst electrode layers 14-1 and 14-2 and the titanium oxide and dye layers 12-1 and 12-2 are formed by laser processing. Each is divided into two. The entire peripheries of the divided catalyst electrode layers 14-1 and 14-2 and the titanium oxide and dye layers 12-1 and 12-2 are insulated and sealed by the sealing portions 15-1 and 15-2. At the same time, in each of the divided cells 1-1 and 1-2, rectangular collector wires 16a-1, 16a-2, 16b-1, and 16b-2 are formed in the sealing portions 15-1 and 15-2. Like that. In particular, in the central portion, the sealing portions 15-1 and 15-2 are integrally formed between the adjacent collector wires 16a-1 and 16a-2 and the adjacent collector wires 16b-1 and 16b-2. It arrange | positions and the collector wires are mutually insulated. A connecting portion 24 is formed at one end portion, for example, at the upper end portion of FIGS. 12, 14 and 16, which are plan views. The connecting portion 24 includes a rectangular current collector 16b-1 disposed on the lower surface of the second transparent substrate 5 (a current collector 16b-1 disposed on the upper right side of the central portion of the cross-sectional view of FIG. 17), A rectangular current collector 16 a-2 disposed on the upper surface of one transparent substrate 3 (current collector 16 a-2 disposed on the lower left side of the center of FIG. 17) is connected in series. The connection unit 24 has the following configuration. A projecting portion 16b-3 projecting outward from the rectangular current collecting wire 16b-1 disposed on the lower surface of the second transparent substrate 5 is formed, and the second transparent is formed at the tip of the projecting portion 16b-3. A bent portion 16b-4 that is bent and attached to the side surface of the substrate 5 is formed. In the vicinity of the bent portion 16 b-4, an overhang portion 16 a-3 that protrudes outward from the rectangular current collecting wire 16 a-2 disposed on the upper surface of the first transparent substrate 3 is formed. In the connection part 24, the position is shifted so that the end part of the first transparent substrate 3 protrudes from the second transparent substrate 5. The bent portion 16b-4 and the overhang portion 16b-3 are 90 degrees out of phase, but are close to each other, so if the solder portion 16e is formed so as to be in electrical contact with both, the electrical connection It can be performed. As a result, the current collecting line 16b-1 on the upper side of the divided cell 1-1 is connected to the lower current collecting line on the lower side of the divided cell 1-2 via the overhanging part 16b-3, the bent part 16b-4, and the solder part 16e. The split cell 1-1 and the split cell 1-2 can be connected in series by being connected to the overhanging portion 16a-3 of 16a-2.

  As a result, as shown in FIGS. 16 and 17, one cell 1 is composed of 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, in order, the first transparent conductive layers 7-1 and 7-2, Titanium oxide and dye layers 12-1 and 12-2, field 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, the titanium oxide and dye layer 12, the electrolysis solution 13, the catalyst electrode layer 14, and the second transparent conductive layer 8 before division.

  According to the first embodiment, at least two or more cells, for example, other than the operation current (Ipm1) of the first cell 1 and the operation current (Ipm2) of the second cell 2 are used as a reference. The ratio of the operating currents of the cells is obtained, and when the ratio is equal to or greater than the threshold value, the cell is divided into a plurality of divided cells, and the divided cells are connected in series. With such a configuration, variation in operating current caused by a difference in pigment or light and shade can be reduced, and power (or output) loss can be reduced.

  Therefore, in the first embodiment, as an example, the cells 1 before division have the same area, the size and shape (outer shape) of each cell itself are constant, and the divided cell in which the inside of each cell is divided The size and shape (outer shape) of each cell does not change before and after the division only by being constituted by 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 design, so that the design is not impaired and the freedom of design is greatly limited. There is nothing.

(Second Embodiment)
As a method for connecting dye-sensitized solar cells according to the second embodiment of the present invention, an example applied when three or more cells are connected in series will be described. Here, non-division, 2-division, 3-division, and 4-division are performed according to the cell.

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

As an example, when these are expressed by concentration,
1st cell 31a: 2nd rich [power generation capacity = 3],
Second cell 31b: the thinnest [power generation capacity = 1],
Third cell 31c: thinnest [power generation capacity = 1],
4th cell 31d: 2nd richest [power generation capacity = 3],
5th cell 31e: 3rd rich [power generation capacity = 2],
Sixth cell 31f: thinnest [power generation capacity = 1],
7th cell 31g: thinnest [power generation capacity = 1],
Eighth cell 31h: darkest [power generation capacity = 4.4],
9th cell 31i: 3rd richest [power generation capacity = 2],
10th cell 31j: thinnest [power generation capacity = 1],
11th cell 31k: 4th rich [power generation capacity = 1.5],
12th cell 31l: thinnest [power generation capacity = 1],
It becomes.

  In determining the ratio, it is assumed that the power generation capacity serving as a reference is a minimum of 1, and the ratio of each cell will be sequentially determined with the power generation capacity 1 as a reference. 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 capacity of the adjacent cells 31a and 31b is 3/1 = 3 and there is a difference of twice or more between adjacent cells. Therefore, the first cell 31a having the higher power generation capacity among the adjacent cells 31a and 31b is a cell to be divided, and as an example, the division number of the first cell 31a is 3/1 = 3. Accordingly, as shown in FIG. 19, it is divided into three divided cells 23.

  Similarly, the power generation capacity of the third cell 31c is 1, whereas the power generation capacity of the fourth cell 31d is 3, and the ratio of the power generation capacity of the adjacent cells 31c and 31d is 3/1. = 3, and there is a difference of twice or more between adjacent cells. Therefore, the fourth cell 31d having the higher power generation capacity among the adjacent cells 31c and 31d is a cell to be divided. As an example, the division number of the fourth cell 31d is 3/1 = 3. Accordingly, as shown in FIG. 19, it is divided into three divided cells 23. The power generation capacity of the fourth cell 31d is 3, which is divided into three, so that the power generation capacity of each divided cell 23 after the division is 1.

  Further, while the power generation capacity of the fifth cell 31e is 2, the power generation capacity of the sixth cell 31f (or the divided cell 23 of the fourth cell 31d) is 1, which is adjacent. The ratio of the power generation capacities of the cells 31e and 31f (or the divided cell 23 of the fourth cell 31d) is 2/1 = 2, and a difference more than twice occurs between adjacent cells. Therefore, the fifth cell 31e having the higher power generation capacity among the adjacent cells 31e and 31f (or the divided cell 23 of the fourth cell 31d) is the cell to be divided, and as an example, The division number of the first cell 31e is 2/1 = 2, so that it is divided into two divided cells 23 as shown in FIG. The power generation capacity of the fifth cell 31e is 2, which is divided into two, so that the power generation capacity of each divided cell 23 after the division is 1.

  The power generation capacity of the seventh cell 31g is 1, whereas the power generation capacity of the eighth cell 31h is 4.4, and the ratio of the power generation capacity of the adjacent cells 31g and 31h is 4. 4/1 = 4.4, and a difference more than twice occurs between adjacent cells. Therefore, the eighth cell 31h having the higher power generation capacity among the adjacent cells 31g and 31h is a cell to be divided, and as an example, the division number of the eighth cell 31h is 4.4 / 1. = 4.4, it is divided into four divided cells 23 as shown in FIG. 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 the division is 1.1.

  In addition, the power generation capacity of the ninth cell 31i is 2, whereas the power generation capacity of the tenth cell 31j is 1, and the ratio of the power generation capacity of the adjacent cells 31i and 31j is 2/1 = 2 and there is a difference of 2 times or more between adjacent cells. Therefore, the ninth cell 31i having the higher power generation capacity among the adjacent cells 31i and 31j is a cell to be divided, and as an example, the division number of the ninth cell 31i is 2/1 = 2. Accordingly, as shown in FIG. 19, it is divided into two divided cells 23. The power generation capacity of the ninth cell 31i is 2, which is divided into two, so that the power generation capacity of each divided cell 23 after the division is 1.

  On the other hand, in the combination of adjacent cells other than those described above, since the ratio of the power generation capacity is less than 2, it is not a division target. For example, the power generation capacity of the second cell 31b is 1, while the power generation capacity of the third cell 31c is 1, and the ratio of the power generation capacity of the adjacent cells 31b and 31c is 1/1 = 1 and there is no difference of 2 times or more between adjacent cells, and it is not a division target. In addition, the power generation capacity of the split cell 23 of the fourth cell 31d is 1, whereas the power generation capacity of the split cell 23 of the fifth cell 31e is 1, and the power generation capacity of the adjacent split cell 23 is also 1. The ratio is 1/1 = 1, and a difference of more than twice does not occur between the adjacent divided cells 23, so that it is not a division target. In addition, the power generation capacity of the split cell 23 of the eighth cell 31h is 1.1, whereas the power generation capacity of the split cell 23 of the ninth cell 31i is 1, and the power of the adjacent split cell 23 is The ratio of the power generation capacity is 1.1 / 1 = 1.1, and there is no difference of 2 times or more between the adjacent divided cells 23, so that the power generation capacity is not divided. The eleventh cell 31k has a power generation capacity of 1.5, whereas the tenth or twelfth cell 31j or 31l has a power generation capacity of 1, and the ratio of the power generation capacity of adjacent cells is 1. Is 1.5 / 1 = 1.5, and a difference of 2 times or more does not occur between adjacent cells, and is not subject to division.

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

  In addition, although the method of calculating | requiring a ratio was calculated | required in order in series connection, it does not necessarily need to obtain | require in order. For example, after determining the reference | standard power generation capability, it calculates | requires by calculating the ratio of all the cells simultaneously. Needless to say, this may be done.

(Third embodiment)
Next, it will be described that in the method of connecting dye-sensitized solar cells according to the third embodiment of the present invention, the threshold value may be less than 2.

In step S3 described above, 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 value, it means that the cell is divided. This threshold is set to double 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 Judgment is made based on whether the ratio value is equal to or greater than a threshold value. Instead of determining whether to divide using such a threshold value, it may be determined whether to divide in 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 It is limited by the operating current I ₁ of the first cell. Here, if both voltages are V, the total output P of the first cell and the second cell in a state where they are not divided is P = {2 · I ₁ · V} (in FIG. 20). (See step S11).

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

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

Specifically, for example, when 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 at 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 the 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 in some cases, and it is understood that the division is more effective.

  This will be described below by rewriting a general expression.

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

The total output P ′ after the 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 dividing, it is necessary to satisfy P <P ′.
{2 · I ₁ · V} <{(n + 1) (m / n · I ₁ · V)}
∴m> {2n / (n + 1)}
When the number n of divisions satisfying this equation is obtained, the total output is higher in the case of division than in the case of no division. For this reason, this expression is 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, based on this equation, the division number n and the threshold value {2n / (n + 1)} are exemplified as shown in Table 1 below.

  Therefore, in the description of step S3, the threshold value is set to 2 times or more. However, from Table 1, it can be seen that the threshold value may be set to 1.33 times or more instead of 2 times or more. In other words, the method of connecting the dye-sensitized solar cells according to the third embodiment is the same as the case of performing the method of connecting the dye-sensitized solar cells according to the previous embodiment by setting the threshold value to 1.33 times. It means to be a result. Therefore, also in this third embodiment, the same operational effects as in the previous embodiment can be achieved.

  In addition, although the ratio is calculated | required between adjacent cells, it is not restricted to this. That is, instead of obtaining the ratio between two adjacent cells, the ratio may be obtained between any two cells of a plurality of cells in one module. One of the two cells may be used as a reference cell, and a ratio between the reference cell and another cell may be obtained in order.

  In addition, the power generation capacity of the cell that serves as a reference for obtaining the ratio is the minimum power generation capacity, but is not limited thereto. For example, if at least two or more cells are composed of three cells, the first cell, the second cell, and the third cell, any of the three cells except the cell with the highest operating current The operating current of the cell (for example, the cell with the second highest 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 a cell other than the cell related to the reference operating current is obtained. This cell may be divided into a plurality of divided cells, and the divided cells may be connected in series.

  Hereinafter, not only the adjacent cells but also an example for obtaining the ratio and an example for obtaining the ratio based on a cell other than the cell with the lowest power generation capacity will be described.

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

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

  In such a case, the ratios between adjacent cells are all 1.3 times, which is less than the above threshold value of 1.33 times. When this threshold value is used, the division is It is considered unnecessary.

  However, when the ratio between the power generation capacity 1.0 of the first cell and the power generation capacity 6.3 of the eighth cell is obtained, it is 6.3 times, which is more than 1.33 times the threshold value described above. I know it ’s good. In this way, the ratio of other cells is calculated based on, for example, the cell having the lowest power generation capacity among all the cells of the dye-sensitized solar cell, instead of calculating the ratio by comparing adjacent cells. In some cases, it may be desirable to consider whether or not to divide. As an example, a column of “ratio to the first cell” is provided in Table 2, and each ratio is obtained. Then, it is understood that it is better to divide all of the third cell to the eighth cell.

  Moreover, although the ratio is calculated | required on the basis of the cell (1st cell in this example) of the lowest electric power generation capability, it demonstrates below that it is not restricted to this. For example, using the third cell as a reference, the ratio of other cells is obtained and the possibility of division is examined. As an example, a column of “Ratio to third cell” is provided in Table 2, and each ratio is obtained. Then, it is understood that it is better to divide all of the fifth cell to the eighth cell.

(Fourth embodiment)
Next, a method for obtaining the optimum number of divisions will be described as a method for connecting the dye-sensitized solar cells according to the fourth embodiment of the present invention. In the previous embodiment, the case where the division is better than the case where the division is not performed is illustrated. However, in that case, the number of divisions may be two or more, and the optimum number of divisions is not pursued. As this 4th Embodiment, the optimal connection method of a dye-sensitized solar cell can be acquired by demonstrating the method of calculating | requiring the optimal division | segmentation number.

  The previous threshold expression is a criterion for determining whether or not the total output can be increased in the case of dividing rather than not dividing, and is different from the determination of the optimum number of divisions.

As an example, the optimal division number 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 the division is equal to or higher than the operating current I ₁ of the first cell (I ₂ / n ≧ 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 the division and the total output P before the 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 the 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 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 the division and the total output P before the 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. Hereinafter, as an example, when the value of the ratio m is 2, 2.2, 2.4, etc., the number of divisions is substituted in order as n = 2, 3, 4,. When 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 an example of how to determine the optimum number of divisions. For example, when the ratio m = 2.6, the number of divisions n = 3 is optimal, but when the number of divisions n = 2, the effect of division is effective. It does not mean that there is nothing. In other words, even if the number of divisions n = 2, if the division is performed, the total output is expected to increase as compared with the case where the division is not performed. Therefore, the present invention is effective.

According to the fourth embodiment, the optimum number of divisions can be obtained according to the ratio of (the operation current I ₂ of the cell to be determined whether to be divided / the operation current I ₁ of the reference cell), and the dye or the light and shade The variation in the operating current caused by the difference can be reduced, and the power (or output) loss can be reduced. As a result, the method for connecting the dye-sensitized solar cells can be carried out more efficiently. Thus, when it divides | segments by the optimal division | segmentation number, an electric power (or output) loss can be minimized.

  As described in the first to fourth embodiments, the number of cells to be divided depends on which cell is used as a reference and the ratio is compared with a threshold value among a plurality of cells constituting one module. Will change. Finally, it is preferable to select and connect the number of divisions that seems to be optimal for the product from the viewpoint of product design or manufacturing costs or labor.

(Test to verify the effect of split processing)
In the following, a test was performed to explain the effect of the division processing of the above-described embodiment.

  In the test, five cells were used for each condition, and a solar simulator for measuring a crystalline solar cell specified 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, a green cell, a red cell, a green cell, a red cell, and a green cell, were connected in series. . Each of these cells is assumed to be a pre-division module including the pre-division cell. Prepare another set of 5 cells with the same configuration as the cell before splitting, of which 2 red cells are split vertically and connected in series, green cells, red split cells A total of seven cells, a red divided cell, a green cell, a red divided cell, a red divided cell, and a green cell, were connected in series. These cells are assumed to be a module after division including the cells after division. The maximum output of the module before division and the module after division was measured seven times for each module.

  Specifically, by using a solar simulator for measuring a crystalline solar cell defined in JIS C 8912: 2011, the power generation capacity of each cell was evaluated by measuring the power generation capacity of each cell before the division and after the division. . This simulator is a solar simulator that uses a xenon lamp, and it represents the air mass (Standard Test Condition: STC) that represents the nominal maximum output of the solar panel. ) (Amount of air until sunlight reaches the ground) Irradiate each cell for about 2 to 3 minutes under the conditions of 1.5, 25 ° C, 1 kW / square meter, and vary the voltage within the specified range. The change in current when measured was measured. Then, based on the measurement results, a curve graph of voltage and current is obtained, and the maximum output is obtained at the point where the maximum square can be taken within the area surrounded by the vertical and horizontal axes of the curve graph and the curve graph. Obtained as the point Pmax. This maximum output point Pmax is obtained for each measurement and is shown in a bar graph in FIG. In FIG. 21, the vertical axis represents the maximum output Pmax, and the horizontal axis represents the cell before division and the cell after division.

  From FIG. 21, the maximum output Pmax is improved by about 30% in the cell after division compared to the cell before division. This is because by dividing the cell in a way that matches the power generation amount of the adjacent cells, power (or output) loss due to power generation is reduced, and the divided cell is more efficient as a solar cell. You can see that

  In addition, this invention is not limited to the said embodiment, It can implement in another various aspect.

  In addition, it can be made to show the effect which each has by combining arbitrary embodiment or modification of the said various embodiment or modification suitably. In addition, combinations of the embodiments, combinations of the examples, or combinations of the embodiments and examples are possible, and combinations of features in different embodiments or examples are also possible.

  The method for connecting the dye-sensitized solar cell and the dye-sensitized solar cell according to the present invention can reduce power (or output) loss by reducing variation in operating current caused by the difference in dye. This is useful when designing the structure of a dye-sensitized solar cell.

  DESCRIPTION OF SYMBOLS 1 ... 1st cell, 1-1, 1-2 ... Divided cell, 2 ... 2nd cell, 3 ... 1st transparent substrate, 4 ... Solar cell element, 5 ... 2nd transparent substrate, 6 ... Internal connection part (interconnect) ), 7... First electrode (first transparent conductive layer), 7 a... Connection terminal, 7-1, 7-2 .. Divided first electrode (divided first transparent conductive layer), 8. Transparent conductive layer), 8a... Connection terminal portion, 8-1 and 8-2... Divided second electrode (divided second transparent conductive layer), 11... Module, 12, 12a. 12-2 ... divided titanium oxide and dye layer, 13, 13a ... electric field solution, 13-1, 13-2 ... divided electric field solution, 14, 14a ... catalytic electrode layer, 14-1, 14-2 ... divided catalytic electrode layer , 15 ... sealing part, 15-1, 15-2 ... split sealing part, 16a, 16b ... current collector, 16a-1, 16a-2, 16b- , 16b-2 ... split current collector, 16a-3, 16b-3 ... overhang, 16b-4 ... bent part, 16e ... solder part, 18 ... lead wire, 20 ... connection line, 21 ... dye sensitized type Solar cell, 23 ... split cell, 24 ... connection part, 25 ... laser processing location, 31a-31l ... cell.

Claims (8)

In the method of connecting dye-sensitized solar cells, wherein 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 the operating currents of all cells, the ratio of each cell is determined based on the cell with the lowest operating current (S2),
Select a cell having a ratio in which the calculated ratio is equal to or greater than a threshold (S3),
Dividing the selected cell into a plurality of divided cells and connecting the divided cells in series (S4);
Method for connecting dye-sensitized solar cells. When selecting cells having a ratio that is greater than or equal to the threshold, the threshold is 2.
The method for connecting the dye-sensitized solar cell according to claim 1. When selecting a cell having a ratio that is greater than or equal to the threshold (S3), select a cell having a ratio that is greater than 2n / (n + 1) that is the threshold;
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 method for connecting the dye-sensitized solar cell according to claim 1. In order to connect the divided cells in series (S4), when dividing the selected cell into n divided cells and connecting the divided cells in series,
For the selected cell, when the total output P ′ of the n divided cells after the division is larger than the output P of the cell before the division, the integer when the output difference ΔP between the cells before and after the division becomes the maximum is the value of n Split as
The connection method of the dye-sensitized solar cell of Claim 3. When obtaining the ratio of each cell based on the cell having the lowest operating current (S2), instead of the cell having the lowest operating current, the cell having the second lowest operating current is used as the reference. Find the ratio with each cell,
The method for connecting the dye-sensitized solar cell according to claim 1. When the divided cells are connected in series (S4), each cell has the same area.
The method for connecting a dye-sensitized solar cell according to any one of claims 1 to 5. When the divided cells are connected in series (S4), each cell has the same area and the same shape,
The connection method of the dye-sensitized solar cell as described in any one of Claims 1-6.   The dye-sensitized solar cell comprised by the said cell and the said division | segmentation cell mutually connecting in series by the connection method of the dye-sensitized solar cell as described in any one of Claims 1-7.

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