JP2004327901A - Light-transmissive thin-film solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily provide a light-transmissive thin-film solar cell module which has desired light transmissivity at a low cost. <P>SOLUTION: The light-transmissive thin-film solar cell module (20) has one or more light-transmissive thin-film solar cell submodules (22) having specified light transmissivity and one or more opaque thin-film solar cell submodules (21) arranged on the same transparent insulating panel, and the ratio of the number of the light-transmissive submodules to the number of the opaque submodules is so set as to obtain desired mean light transmissivity on the whole light-transmissivity module. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light-transmitting thin-film solar cell module, and more particularly to a light-transmitting thin-film solar cell module that can easily achieve a desired light transmittance at low cost when used for a building.
[0002]
[Prior art]
In recent years, from the viewpoint of preventing global warming due to carbon dioxide emission, the use of semiconductor solar cells as a clean energy source is expected to expand. Among semiconductor solar cells, a thin-film solar cell using a semiconductor thin film formed by vapor deposition can be manufactured in a large area at a low cost as compared with a crystalline solar cell using a semiconductor crystal wafer. Is expected.
[0003]
8 to 11, the structure of a typical conventional thin-film solar cell is schematically illustrated. 8 is a plan view showing the back surface of the thin-film solar cell, FIG. 9 is a cross-sectional view along line A in FIG. 8, and FIG. 10 is a cross-sectional view along line B in FIG. FIG. 11 is a schematic perspective view of a portion cut along a dotted line C in FIG. In the drawings of the present application, the same reference numerals represent the same or corresponding parts.
[0004]
In the thin-film solar cell 1 illustrated in FIGS. 8 to 11, the transparent electrode layer 3, the semiconductor photoelectric conversion layer 4, and the back metal electrode layer 5 are formed on a transparent insulating substrate 2 such as glass by sputtering or CVD (chemical vapor deposition). The layers are sequentially stacked using vapor deposition. In recent years, glass substrates 2 having a size of about 1 m square have been used. As the transparent electrode layer 3, ZnO, SnO ₂ , ITO (indium tin oxide) or the like is used, and as the metal electrode layer 5, Ag, Al, or the like is mainly used. A plurality of strip-shaped photoelectric conversion cells 16 are formed by repeating the deposition of each layer 3, 4, 5 and patterning by etching or laser scribing, and these strip-shaped cells 16 are electrically connected in series in the short axis direction. Integrated structure.
[0005]
That is, the back electrode layer 5 is separated between the adjacent cells 16 by the inter-cell separation groove 6, but the transparent electrode 3 of one cell 16 is connected to the back electrode 5 of the adjacent cell 16. Each of the layers 3, 4, 5 is separated into a power generation region 13 and a non-power generation region 14 by a peripheral separation groove 11. Such a peripheral separation groove 11 is provided for separating a short-circuit defect between the transparent electrode 3 and the back electrode 5 at the peripheral end of each of the layers 3, 4, and 5. In such a case, a light transmittance of less than 1% exists in the power generation region due to the inter-cell separation groove 6.
[0006]
Bus bar (bus) electrodes 12 are provided on cells at both ends of the plurality of cells connected in series, and output currents from all cells are taken out of these bus bar electrodes 12. As shown in FIG. 9, one of the bus bar electrodes 12 is connected to the transparent electrode 3 by the solder layer 17 via the connection groove 7. Then, the other bus bar electrode 12 may be connected to the back surface electrode 5 by a solder layer.
[0007]
Conventionally, large thin-film solar cells for buildings are generally installed on the roof of a building or the roof of a house. However, recently, from the viewpoint of improving the use efficiency of the sunshine space, thin-film solar cells are installed not only on the roof of a building or the roof of a house, but also on the wall of a building. Also, attempts have been made to use thin-film solar cells for windows of buildings, roofs for lighting, and roofs of arcades in shopping streets. When thin-film solar cells are used for the building roof itself, windows, or arcade roofs, the thin-film solar cells partially transmit sunlight as illumination light inside the building or in the arcade. There is a need to.
[0008]
An example of a thin-film solar cell that can transmit part of sunlight is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-251723 of Patent Document 1.
[0009]
12 and 13, an example of a translucent thin-film solar cell is schematically illustrated. FIG. 12 is a plan view showing the back surface of the translucent thin-film solar cell, and FIG. 13 is a schematic perspective view of a portion cut along a dotted line D in FIG. The sectional structures along the line segments A and B in FIG. 12 correspond to FIGS. 2 and 3, respectively. In the light-transmitting thin-film solar cell 1 a of FIG. 12, sunlight can partially pass through the power generation region 15.
[0010]
The reason why the power generation area 15 can partially transmit sunlight is because a plurality of light transmission grooves 8 are formed as shown in FIG. That is, the semiconductor layer 4 and the metal electrode layer 5 are removed by the light transmitting groove 8. However, the light transmission groove 8 is formed so as to intersect the inter-cell separation groove 6, and the cells on both sides of the inter-cell separation groove 6 maintain an electrical series connection with each other. Needless to say, a light transmitting hole may be formed instead of the light transmitting groove.
[0011]
[Patent Document 1]
JP-A-5-251723
[Problems to be solved by the invention]
When a translucent thin-film solar cell is installed on a building window itself, a lighting roof itself, or an arcade roof itself and a part of sunlight is used as illumination light, the translucent thin-film solar cell is required. Light transmittance is not constant. This is because the required brightness of the illumination light is not always constant depending on the use of the room in the building.
[0013]
On the other hand, in a light-transmitting thin-film solar cell as illustrated in FIG. 13, the light transmittance is determined depending on the width and density (the number of light-transmitting grooves 8) of the light-transmitting grooves 8. That is, the light transmittance of the completed translucent thin-film solar cell cannot be changed. Therefore, in order to produce a light-transmitting thin-film solar cell having the required light transmittance, the design must be changed for each light transmittance, and the manufacturing process must be changed accordingly.
[0014]
For example, when a half transmittance is required as compared with the translucent thin-film solar cell of FIG. 13, the density (number) of the light transmission grooves 8 is reduced to half as shown in FIG. As shown in FIG. 15, the design must be changed so that the width of each of the light transmitting grooves 8 is reduced to half. Of course, if it is necessary to increase the light transmittance, the density of the light transmitting grooves 8 must be increased and / or the width of each light transmitting groove 8 must be increased. By adjusting the width and the density of the light transmitting groove in this manner, for example, a light transmittance within a range of 3% to 50% can be realized.
[0015]
When a light transmitting hole is formed instead of the light transmitting groove, the relationship of the groove width corresponds to the relationship of the hole diameter, and the relationship of the number of grooves corresponds to the size of the hole. Respond to relationships. In a light-transmitting thin-film solar cell, it goes without saying that the output power decreases as the light transmittance increases. Therefore, the light transmittance of the translucent thin-film solar cell is determined in consideration of both the desired brightness of the transmitted light and the desired output power.
[0016]
Further, in order to manufacture a light-transmitting thin-film solar cell having a changed light transmittance, for example, in a laser scribe for forming the light transmission groove 8, a change in the number of scribe scans and / or a change in laser power. And so on. Such design changes and process changes not only increase the cost of the translucent thin-film solar cell, but also complicate the process.
[0017]
In view of the state of the prior art as described above, an object of the present invention is to provide a light-transmitting thin-film solar cell having a desired light transmittance at a low cost and easily.
[0018]
[Means for Solving the Problems]
In the light-transmitting thin-film solar cell module according to the present invention, one or more light-transmitting thin-film solar cell submodules having a predetermined light transmittance and one or more non-light-transmitting thin-film solar cell submodules have the same transparent insulation. The light-transmitting sub-modules are arranged on the panel, and the ratio of the number of the light-transmitting sub-modules to the non-light-transmitting sub-modules is set so that a desired average light transmittance is obtained as a whole of the light-transmitting module. I have.
[0019]
The translucent sub-module and the non-translucent sub-module can be electrically connected to each other so that their output currents are combined and taken out as one output current from the entire translucent module. In this case, it is preferable that a plurality of predetermined sub-modules include a plurality of parallel sub-module groups electrically connected in parallel, and the plurality of parallel sub-module groups are electrically connected in series. Preferably, the plurality of parallel sub-module groups include the same number of translucent sub-modules.
[0020]
Both the light-transmitting sub-module and the non-light-transmitting sub-module can be manufactured to include a transparent electrode layer, a semiconductor photoelectric conversion layer, and a back electrode layer which are sequentially stacked on a transparent insulating substrate. The sub-module may include a plurality of light-transmitting grooves or holes penetrating the semiconductor photoelectric conversion layer and the back electrode layer. Each of the sub-modules has busbar electrodes on the back electrode layer along both sides to extract its output current, and electrical connection between the submodules is performed by joining connection leads between the busbar electrodes. Can be.
[0021]
The back side of the back electrode layer can be sealed by a transparent insulating panel via a transparent sealing resin layer. Further, it is preferable that a weather-resistant and insulating filling resin is provided in a gap between the transparent insulating substrates of the plurality of sub-modules disposed on the transparent insulating panel. Further, it is preferable that an insulating film is inserted between a position where the connection lead directly faces the back electrode layer and a position where the connection lead faces an adjacent region between the submodules.
[0022]
The translucent sub-modules and the non-translucent sub-modules are preferably arranged in a predetermined periodic pattern on the panel so that the illumination effect of the entire translucent module by the transmitted light is uniform.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
As an example of a general manufacturing process of a light-transmitting thin-film solar cell, after processing a light-transmitting groove or hole by a laser processing device,
(1) Perform cleaning,
(2) Annealing is performed in addition to cleaning.
(3) A high output performance of the solar cell can be obtained by performing any one of annealing in addition to brush cleaning as a cleaning step. In order to secure such high output characteristics, an annealing process (for example, at 150 ° C. for 20 minutes or more) is an essential step. It is most preferable to use both the brush cleaning step and the annealing treatment for the production of the light-transmitting thin-film solar cell.
[0024]
Further, in the light-transmitting thin-film solar cell, since a large number of light-transmitting grooves or holes are provided in the power generation region, the cells tend to be defective and current leakage tends to occur. Therefore, when the amorphous semiconductor photoelectric conversion layer is about 330 nm thicker than a normal film thickness, the output characteristics after light degradation due to the so-called Stepler-Lonski effect are maximized. That is, in the case of a light-transmitting thin-film solar cell, the amorphous semiconductor photoelectric conversion layer preferably has a thickness in the range of 300 to 350 nm.
[0025]
1 to 3, a light-transmitting thin-film solar cell module according to an embodiment of the present invention is schematically illustrated. FIG. 1 is a schematic plan view showing the back surface of the translucent thin-film solar cell module, and FIGS. 2 and 3 show cross sections orthogonal to each other in a region E indicated by a broken line in FIG. .
[0026]
The light-transmitting thin-film solar cell module 20 includes two non-light-transmitting thin-film solar cell sub-modules 21 arranged diagonally and two light-transmitting thin-film solar cell sub-modules arranged opposite diagonally. 22 (see FIG. 1). The back surfaces of these submodules 21 and 22 are sealed by a transparent insulating panel 32 made of a glass plate or the like via a sealing resin layer 31 made of, for example, EVA (ethylene vinyl acetate) (see FIG. 2 and FIG. 2). (See FIG. 3). For example, four 500 cm square sub-modules 21 and 22 can be arranged on an approximately 1 m square transparent insulating panel 32.
[0027]
As shown in FIG. 1, in a light-transmitting thin-film solar cell module including four sub-modules, the non-light-transmitting and light-transmitting sub-modules to be attached to the transparent insulating panel 32 are selected. Light transmittance can be easily realized at low cost. That is, among the sub-modules to be attached on the transparent insulating panel 32, the number of the translucent sub-modules 22 can be selected from 1 to 4, and as the number increases, the number of the translucent thin-film solar cell modules increases. The average light transmittance as a whole increases.
[0028]
As can be seen from FIG. 1, in the submodules adjacent to each other on the left and right, the bus bar electrodes 12 are electrically connected in parallel to each other by a ribbon-shaped connection lead 18 made of, for example, solder-plated copper foil (perpendicular to each other). (See also FIG. 2 and FIG. 3 which are cross-sectional views.) That is, the non-light-transmitting sub-module 21 and the light-transmitting sub-module 22 adjacent to each other form a parallel sub-module group, whereby an output current averaged between the modules is obtained. The vertically adjacent parallel sub-module groups are electrically connected to each other in series by the connection lead 18, whereby a desired output voltage can be obtained. Then, output power from all the sub-modules included in the translucent thin-film solar cell module is taken out from the two output terminals 19.
[0029]
The translucent thin-film solar cell module illustrated in FIGS. 1 to 3 can be manufactured, for example, by the following procedure. First, in order to stabilize the arrangement of the submodules 21 and 22 before being fixed to the transparent insulating panel 32 and to facilitate handling, the back electrode was placed on a sheet of, for example, a glass nonwoven fabric coated with a fluororesin. Place those submodules in a state.
[0030]
The bus bar electrodes 12 of the left and right sub-modules 21 and 22 are electrically connected in parallel by the connection leads 18 made of solder-plated copper foil to form a parallel sub-module group. Further, the connection leads 18 electrically connect the bus bar electrodes 12 of the vertically adjacent parallel sub-module groups in series. An output terminal 19 similar to the connection lead 18 is also connected to the bus bar electrode 12.
[0031]
Thereafter, a first EVA sheet having the same area as the transparent insulating panel 32 and having a thickness of, for example, 0.4 mm is covered as a part of the sealing resin layer on all the sub-modules for which electrical connection has been completed. At this time, a cut is provided at the position of the connection lead 18 in the first EVA sheet. Then, the cut portion of the first EVA sheet is inserted between the connection lead 18 and the sub-modules 21 and 22. Thereafter, a second EVA sheet having the same area and a thickness of 0.4 mm is covered so as to cover the entire first EVA sheet.
[0032]
A glass plate as the transparent insulating panel 32 is placed on the second EVA sheet. Then, in this state, vacuum lamination is performed. In vacuum lamination, for example, a vacuum process is performed at 160 ° C. for 2 minutes, and then a press process is performed, for example, for 6 minutes. Thereafter, in order to increase the strength of the EVA layer, a hardening (curing) treatment is performed by heating at 150 ° C. for 1 hour under normal pressure in an oven. Thus, the first and second EVA sheets become an integral sealing resin layer 31.
[0033]
FIG. 4 similar to FIG. 3 is a schematic cross-sectional view showing another embodiment in which a part of the above-described embodiment is changed. That is, when a sub-module is pasted on the transparent insulating panel 32, a filling resin 34 is applied to the gap 33 (see FIG. 3) between the glass substrates 2 of adjacent sub-modules as shown in FIG. Is preferred. This is because the EVA sheet used for forming the sealing resin layer 31 is extremely thin as described above, and the gap 33 between the adjacent glass substrates 2 cannot be filled with the EVA resin.
[0034]
That is, moisture or the like in the air may enter between the glass substrate 2 and the sealing resin layer 31 from the gap 33 to cause a current leak between the wirings and a deterioration of the power generation region. This is because long-term reliability of the battery module can be a problem. In addition, as such a filling resin 34, it is preferable to use a weather-resistant and insulating silicone resin or butyl resin.
[0035]
FIG. 5 similar to FIG. 4 is a schematic cross-sectional view showing still another embodiment in which a part of the embodiment of FIG. 4 is modified. That is, as shown in FIG. 5, in a region where the connection lead 18 for connecting the bus bar electrodes 12 faces the back metal electrode layer, it is preferable to insert the insulating film 35 therebetween. This makes it possible to more reliably prevent a current leak between the connection lead 18 and the back metal electrode layer, which is preferable from the viewpoint of the reliability of the translucent thin-film solar cell module.
[0036]
FIG. 6 is a schematic plan view showing the back side of a translucent thin-film solar cell module according to still another embodiment of the present invention. The translucent thin-film solar cell modules 20 are arranged in a checkered pattern. It includes two non-light-transmitting sub-modules 21 and eight light-transmitting sub-modules. For example, 16 submodules 21 and 22 each having a square of about 250 cm can be arranged on a transparent insulating panel having a square of about 1 m.
[0037]
As shown in FIG. 6, in the light-transmitting thin-film solar cell module including 16 sub-modules, by selecting non-light-transmitting and light-transmitting sub-modules to be attached to the transparent insulating panel, there are 16 ways. Can be easily realized at low cost. In other words, the number of translucent sub-modules 22 can be selected from 1 to 16 among the sub-modules to be attached on the transparent insulating panel, and as the number increases, the number of translucent thin-film solar cell modules 20 increases. The average light transmittance as a whole increases.
[0038]
FIG. 7 shows an equivalent circuit diagram of the translucent thin-film solar cell module of FIG. That is, the four submodules adjacent to each other on the left and right are electrically connected in parallel to each other, forming a parallel submodule group. As a result, an output current averaged between the modules is obtained. The four parallel sub-module groups vertically arranged are electrically connected to each other in series. Thereby, a desired output voltage is obtained. Then, output power from all the sub-modules included in the translucent thin-film solar cell module is taken out from the two output terminals 19.
[0039]
By the way, as compared with the non-light-transmitting sub-module 21, the output current of the light-transmitting sub-module 22 is relatively low, and the output current is reduced in inverse proportion to the light transmittance. Generally, when a submodule having a large output current and a submodule having a small output current are connected in series, the output current of the module as a whole is limited by the submodule having the smaller output current. Therefore, it is preferable that each of the plurality of parallel sub-module groups includes the same number of translucent sub-modules.
[0040]
Further, in order to generate a uniform illumination effect in the whole thin-film solar cell module, it is preferable that the non-light-transmitting sub-modules and the light-transmitting sub-modules are arranged in a periodic pattern. When arranged in such a periodic pattern, a plurality of parallel sub-module groups may inevitably include the same number of translucent sub-modules.
[0041]
【The invention's effect】
As described above, according to the present invention, a light-transmitting thin-film solar cell module having a desired light transmittance can be easily provided at low cost.
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing the back side of a translucent thin-film solar cell module according to one embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view in a broken line area E in FIG.
FIG. 3 is a schematic cross-sectional view in a direction orthogonal to FIG. 2 in a dashed area E in FIG. 1;
FIG. 4 is a sectional view showing an embodiment in which a part of FIG. 3 is modified.
FIG. 5 is a sectional view showing an embodiment in which a part of FIG. 4 is modified.
FIG. 6 is a schematic plan view showing the back side of a translucent thin-film solar cell module according to a further embodiment of the present invention.
FIG. 7 is an equivalent circuit diagram corresponding to the translucent thin-film solar cell module of FIG.
FIG. 8 is a schematic plan view showing the back side of a conventional non-translucent thin-film solar cell.
FIG. 9 is a schematic sectional view taken along line A in FIG.
FIG. 10 is a schematic sectional view taken along line B in FIG. 8;
11 is a schematic perspective view of a portion cut along a dotted line C in FIG.
FIG. 12 is a schematic plan view showing the back side of a conventional translucent thin-film solar cell.
13 is a schematic perspective view of an example of a portion cut out along a dotted line D in FIG.
FIG. 14 is a schematic perspective view of another example of a portion cut out along a dotted line D in FIG.
FIG. 15 is a schematic perspective view of still another example of a portion cut out along a dotted line D in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Conventional non-transparent thin film solar cell, 1a Conventional translucent thin film solar cell, 2 Transparent insulating substrate, 3 Transparent electrode layer, 4 Semiconductor photoelectric conversion layer, 5 Backside metal electrode layer, 6 Separation groove between cells, 7 Connection groove, 8 light transmission groove, 11 peripheral separation groove, 12 bus bar electrode, 13 power generation area, 14 non-power generation area, 15 light-transmitting power generation area, 16 photoelectric conversion cell, 17 solder layer, 18 connection lead, 19 output terminal , 20 translucent thin-film solar cell module, 21 non-translucent thin-film solar cell submodule, 22 translucent thin-film solar cell submodule, 31 sealing resin layer, 32 transparent insulating panel, 33 gap, 34 filling resin, 35 Insulating film.

Claims (10)

One or more translucent thin-film solar cell submodules having a predetermined transmissivity and one or more non-translucent thin-film solar cell submodules are arranged on the same transparent insulating panel. A module, wherein a ratio of the number of the light-transmitting sub-modules to the non-light-transmitting sub-module is set such that a desired average light transmittance is obtained as a whole of the light-transmitting module. Translucent thin-film solar cell module. The translucent sub-module and the non-translucent sub-module are electrically connected to each other such that their output currents are combined and taken out as one output current from the entire translucent module. The translucent thin-film solar cell module according to claim 1, wherein: The predetermined plurality of sub-modules includes a plurality of parallel sub-module groups electrically connected in parallel, and the plurality of parallel sub-module groups are electrically connected in series. 3. The translucent thin-film solar cell module according to item 1. The translucent thin-film solar cell module according to claim 3, wherein the plurality of parallel sub-module groups include the same number of translucent sub-modules. Both the light-transmitting sub-module and the non-light-transmitting sub-module include a transparent electrode layer, a semiconductor photoelectric conversion layer, and a back electrode layer which are sequentially stacked on a transparent insulating substrate. 5. The light-transmitting thin-film solar cell module according to claim 1, comprising a plurality of light-transmitting grooves or holes penetrating the semiconductor photoelectric conversion layer and the back electrode layer. 6. Each of the sub-modules has a bus bar electrode on the back electrode layer along both sides to extract its output current, and the electrical connection between the sub-modules joins connection leads between the bus bar electrodes. The translucent thin-film solar cell module according to claim 5, wherein the light-transmitting thin-film solar cell module is performed. The translucent thin-film solar cell module according to claim 5, wherein a back side of the back electrode layer is sealed by the transparent insulating panel via a transparent sealing resin layer. The translucent resin according to claim 7, wherein a weather-resistant and insulating filling resin is provided in a gap between the transparent insulating substrates of the plurality of sub-modules disposed on the transparent insulating panel. Thin film solar cell module. 7. The transparent film according to claim 6, wherein an insulating film is inserted between a position where the connection lead directly faces the back electrode layer and a position where it faces an adjacent region between the sub-modules. Optical thin-film solar cell module. The translucent sub-modules and the non-translucent sub-modules are arranged in a predetermined periodic pattern on the panel so that the illumination effect of the entire transmissive module by the transmitted light is uniform. The translucent thin-film solar cell module according to claim 1, wherein:

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