JP4358549B2 - Translucent thin film solar cell module - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a translucent thin film solar cell module, and more particularly to a translucent thin film solar cell module that can easily achieve a desired translucency at low cost when used for building applications.
[0002]
[Prior art]
In recent years, from the viewpoint of preventing global warming due to carbon dioxide emission, the use of semiconductor solar cells is expected to be expanded as a clean energy source. Among semiconductor solar cells, thin-film solar cells that use semiconductor thin films by vapor deposition can be fabricated at a low cost and in large areas compared to crystalline solar cells that use semiconductor crystal wafers. Is expected.
[0003]
8 to 11, the structure of a conventional typical 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 taken along line A in FIG. 8, and FIG. 10 is a cross-sectional view taken along line B in FIG. FIG. 11 is a schematic perspective view of a portion cut out along a dotted line C in FIG. In the drawings of the present application, the same reference numerals denote the same or corresponding parts.
[0004]
In these thin film solar cells 1 illustrated in FIGS. 8 to 11, the transparent electrode layer 3, the semiconductor photoelectric conversion layer 4, and the back surface metal electrode layer 5 are formed on a transparent insulating substrate 2 such as glass by sputtering or CVD (chemical The layers are sequentially stacked using vapor deposition. In recent years, glass substrates 2 having a size of about 1 m 2 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 minor axis direction. Integrated structure.
[0005]
That is, the back electrode layer 5 is separated between 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 layer 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 in order to separate a short-circuit defect between the transparent electrode 3 and the back electrode 5 at the peripheral edge of each layer 3, 4, 5. In such a case, a translucency of less than 1% exists due to the inter-cell separation groove 6 in the power generation region.
[0006]
Bus bar (bus) electrodes 12 are provided on the cells at both ends of the plurality of cells connected in series, and output current from all the cells is taken out from 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 through the connection groove 7. And the other bus-bar electrode 12 should just be connected to the back surface electrode 5 by the solder layer.
[0007]
Conventionally, large-sized thin-film solar cells for buildings are generally installed on the roof of a building or the roof of a house. Recently, however, thin-film solar cells have been installed not only on the roofs of buildings and roofs of houses, but also on the walls of buildings, from the viewpoint of improving the utilization efficiency of sunshine spaces. Attempts have also been made to use thin-film solar cells for building windows themselves, daylighting roofs themselves, and arcade roofs of shopping streets themselves. Here, when using thin-film solar cells for daylighting roofs of buildings, windows themselves, or arcade roofs themselves, the thin-film solar cells partially transmit sunlight as illumination light inside the building or arcades. 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.
[0009]
In FIG. 12 and FIG. 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 out along a dotted line D in FIG. The cross-sectional structures along line segments A and B in FIG. 12 correspond to FIGS. 2 and 3, respectively. In the translucent thin film solar cell 1 a of FIG. 12, sunlight can be partially transmitted in the power generation region 15.
[0010]
The reason why the power generation region 15 can partially transmit sunlight is that, as shown in FIG. 13, a plurality of light transmission grooves 8 are formed. 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 are maintained in 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 daylighting 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. The 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 the translucent thin film solar cell as illustrated in FIG. 13, the light transmittance is determined depending on the width and density (slight number) of the light transmitting grooves 8. That is, in the translucent thin film solar cell after completion, the light transmittance cannot be changed. Therefore, in order to produce a translucent 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 half the transmissivity is required as compared with the translucent thin film solar cell of FIG. 13, the density (number) of the light transmitting grooves 8 is halved as shown in FIG. As shown in FIG. 15, the design must be changed so that the width of each light transmitting groove 8 is halved. Of course, if it is required 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. Thus, by adjusting the width and density of the light transmitting groove, it is possible to realize a light transmittance within a range of 3% to 50%, for example.
[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. Corresponds to the relationship. Needless to say, in the light-transmitting thin-film solar cell, 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 produce a light-transmitting thin film solar cell with a changed light transmittance, for example, in laser scribing for forming the light transmitting groove 8, a change in the number of scribe scans and / or a change in laser power is performed. Etc. must be done. Such a design change or process change increases the cost of the translucent thin film solar cell, but also complicates the process.
[0017]
In view of the state of the prior art as described above, an object of the present invention is to easily provide a translucent thin film solar cell having a desired light transmittance at a low cost.
[0018]
[Means for Solving the Problems]
In the translucent thin film solar cell module according to the present invention, the one or more translucent thin film solar cell submodules having a predetermined translucency and the one or more non-translucent thin film solar cell submodules are the same transparent insulation. The ratio of the number of translucent sub-modules to the non-translucent sub-modules arranged on the panel is set so as to obtain a desired average transmissivity for the entire translucent module. Yes.
[0019]
The translucent submodule and the non-translucent submodule 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. At this time, it is preferable that a plurality of parallel submodule groups each including a predetermined plurality of submodules electrically connected in parallel are included, and the plurality of parallel submodule groups are electrically connected in series. The plurality of parallel submodule groups preferably include the same number of light transmitting submodules.
[0020]
Transparent electrode layer both are laminated in this order on a transparent insulating substrate of the translucent submodule and non-translucent submodule, the semiconductor photoelectric conversion layer, and made include backside electrode layer, the light transmitting submodule including a plurality of magnetic light groove or hole through the semiconductor photoelectric conversion layer and the back electrode layer. Each of the submodules has a bus bar electrode on the back electrode layer along both sides to take out its output current, and the electrical connection between the sub modules is performed by joining connection leads between the bus bar electrodes. Can be broken.
[0021]
The back side of the back electrode layer can be sealed with a transparent insulating panel via a transparent sealing resin layer. Moreover, it is preferable that the weatherproof and insulating filling resin is provided to the gap between the transparent insulating substrates of the plurality of submodules arranged on the transparent insulating panel. Further, it is preferable that an insulating film is inserted between the connection lead directly facing the back electrode layer and the position facing the adjacent region between the submodules.
[0022]
It is preferable that the translucent submodule and the non-translucent submodule are arranged in a predetermined periodic pattern on the panel so that the illumination effect by the transmitted light of the entire translucent module becomes uniform.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
As an example of a general manufacturing process of a translucent thin film solar cell, after processing a translucent groove or hole by a laser processing apparatus,
(1) Perform cleaning.
(2) In addition to cleaning, anneal
(3) High output performance of the solar cell can be obtained by performing any of annealing in addition to brush cleaning as a cleaning step. In order to ensure such high output characteristics, an annealing process (for example, at 150 ° C. for 20 minutes or more) is an essential process. And it is most preferable to use a brush washing process and an annealing process together for manufacture of a translucent thin film solar cell.
[0024]
Moreover, in a translucent thin film solar cell, since many translucent grooves or holes are provided in the power generation region, defects tend to occur in the cell and current leakage tends to occur. Therefore, when the amorphous semiconductor photoelectric conversion layer is about 330 nm thicker than the normal film thickness, the output characteristics after photodegradation due to the so-called Stebleronsky effect are maximized. That is, in the case of a translucent thin film solar cell, the amorphous semiconductor photoelectric conversion layer is preferably in the thickness range of 300 to 350 nm.
[0025]
1 to 3 schematically illustrate a translucent thin film solar cell module according to an embodiment of the present invention. FIG. 1 is a schematic plan view showing the back surface of a translucent thin film solar cell module, and FIGS. 2 and 3 show cross sections orthogonal to each other within a region E indicated by a broken line in FIG. .
[0026]
The translucent thin film solar cell module 20 includes two non-translucent thin film solar cell submodules 21 arranged in a diagonal direction and two translucent thin film solar cell submodules arranged in the opposite diagonal direction. 22 (see FIG. 1). The back surfaces of these submodules 21 and 22 are sealed with 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) (FIG. 2 and FIG. 2). (See FIG. 3). For example, four sub-modules 21 and 22 of about 500 cm square can be arranged on the transparent insulating panel 32 of about 1 m square.
[0027]
In the translucent thin film solar cell module including four submodules as shown in FIG. 1, by selecting the non-translucency and translucency of the submodule attached to the transparent insulating panel 32, 4 The light transmittance can be easily realized at low cost. That is, among the submodules attached on the transparent insulating panel 32, the number of translucent submodules 22 can be selected from 1 to 4, and the translucent thin film solar cell module increases as the number increases. The average light transmittance as a whole increases.
[0028]
As can be seen from FIG. 1, in the left and right submodules, the bus bar electrodes 12 are electrically connected in parallel to each other by a ribbon-shaped connection lead 18 made of, for example, a solder-plated copper foil (orthogonal to each other). (See also FIGS. 2 and 3 which are cross-sectional views). That is, the non-translucent submodule 21 and the translucent submodule 22 adjacent to the left and right constitute a parallel submodule group, thereby obtaining an output current averaged between the modules. Further, the parallel submodule groups adjacent to each other in the vertical direction are electrically connected to each other in series by the connection leads 18, thereby obtaining a desired output voltage. Then, output power from all submodules 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 facilitate handling, for example, a back electrode was placed on a sheet of glass nonwoven fabric coated with a fluororesin. Place those submodules in a state.
[0030]
The bus bar electrodes 12 of the submodules 21 and 22 adjacent to the left and right are electrically connected in parallel by connection leads 18 made of solder-plated copper foil to form a parallel submodule group. Further, the busbar electrodes 12 of the parallel submodule groups adjacent in the vertical direction are electrically connected in series with the connection leads 18. 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 that of the transparent insulating panel 32 and having a thickness of 0.4 mm, for example, is placed as a part of the sealing resin layer on all the submodules that have been electrically connected. At this time, in the first EVA sheet, a cut is provided at the position of the connection lead 18. 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. In this state, vacuum lamination is performed. In vacuum lamination, for example, after evacuating for 2 minutes at 160 ° C., for example, pressing is performed for 6 minutes. Thereafter, in order to increase the strength of the EVA layer, curing (curing) treatment is performed by heating at 150 ° C. for 1 hour in an oven under normal pressure. 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 the submodule is attached on the transparent insulating panel 32, the filling resin 34 is applied to the gap 33 (see FIG. 3) between the glass substrates 2 of the adjacent submodules as shown in FIG. It is preferable. This is because the EVA sheet used for forming the sealing resin layer 31 is very 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 in the air may enter between the glass substrate 2 and the sealing resin layer 31 from the gap 33, which may cause current leakage between the wirings or deterioration of the power generation region. This is because the long-term reliability of the battery module can be a problem. As such a filling resin 34, it is preferable to use a weather-resistant and insulating silicone-based resin or butyl-based 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 changed. That is, as shown in FIG. 5, in a region where the connection leads 18 that connect the bus bar electrodes 12 face the back metal electrode layer, it is preferable to insert the insulating film 35 therebetween. Thus, current leakage between the connection lead 18 and the back metal electrode layer can be prevented more reliably, 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 module 20 is arranged in a checkered pattern. One non-translucent submodule 21 and eight translucent submodules are included. For example, 16 sub-modules 21 and 22 of about 250 cm square can be arranged on a transparent insulating panel of about 1 m square.
[0037]
In the translucent thin film solar cell module including 16 submodules as shown in FIG. 6, 16 types are selected by selecting the non-translucency and translucency of the submodule attached to the transparent insulating panel. The light transmittance can be easily realized at low cost. That is, among the submodules attached on the transparent insulating panel, the number of translucent submodules 22 can be selected from 1 to 16, and the translucent thin film solar cell module 20 is increased as the number 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 sub modules adjacent to the left and right are electrically connected to each other in parallel to form a parallel sub module group. This provides an averaged output current between modules. The four parallel submodule groups arranged in the vertical direction are electrically connected in series with each other. As a result, a desired output voltage can be obtained. Then, output power from all submodules 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-translucent submodule 21, the output current of the translucent submodule 22 is naturally relatively low, and the output current decreases in inverse proportion to the light transmittance. In general, 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 the plurality of parallel submodule groups each include the same number of translucent submodules.
[0040]
Moreover, in order to produce the uniform illumination effect as the whole thin film solar cell module, it is preferable that the non-translucent submodule and the translucent submodule are arranged in a periodic pattern. If arranged in such a periodic pattern, a plurality of parallel submodule groups inevitably include the same number of translucent submodules.
[0041]
【The invention's effect】
As described above, according to the present invention, it is possible to easily provide a translucent thin film solar cell module having a desired light transmittance at a low cost.
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing a back side of a translucent thin film solar cell module according to an embodiment of the present invention.
2 is a schematic cross-sectional view in a broken line area E in FIG.
3 is a schematic cross-sectional view in a direction orthogonal to FIG. 2 within a broken line area E in FIG. 1;
4 is a cross-sectional view showing an embodiment in which a part of FIG. 3 is modified.
FIG. 5 is a cross-sectional view showing an embodiment in which a part of FIG. 4 is modified.
FIG. 6 is a schematic plan view showing a back side of a translucent thin film solar cell module according to a further embodiment of the present invention.
7 is an equivalent circuit diagram corresponding to the translucent thin film solar cell module of FIG. 6. 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 cross-sectional view taken along line A in FIG.
10 is a schematic cross-sectional view taken along a line segment B in FIG. 8. FIG.
11 is a schematic perspective view of a portion cut out 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.
14 is a schematic perspective view of another example of a portion cut out along a dotted line D in FIG. 12. 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-light-transmissive thin film solar cell, 1a Conventional light-transmissive thin film solar cell, 2 Transparent insulating substrate, 3 Transparent electrode layer, 4 Semiconductor photoelectric conversion layer, 5 Back surface metal electrode layer, 6 Inter-cell isolation groove, 7 Connection groove, 8 Light transmission groove, 11 Perimeter separation groove, 12 Busbar electrode, 13 Power generation area, 14 Non-power generation area, 15 Light transmission 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-transparent 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 (8)

One or more translucent thin-film solar cell submodules having a predetermined translucency and one or more non-transparent thin-film solar cell submodules are disposed on the same transparent insulating panel. A module,
Each of the translucent submodule and the non-translucent submodule includes a transparent electrode layer, a semiconductor photoelectric conversion layer, and a back electrode layer that are sequentially laminated on a transparent insulating substrate,
The translucent submodule further includes a plurality of translucent grooves or holes penetrating the semiconductor photoelectric conversion layer and the back electrode layer,
The ratio of the number of the translucent submodules to the non-translucent submodule is set so that a desired average translucency can be obtained as the entire translucent module ,
The back side of the back electrode layer is sealed by the transparent insulating panel via a transparent sealing resin layer,
A translucent thin film solar cell module, characterized in that a weather-resistant and insulating filling resin is applied to gaps between the transparent insulating substrates of the plurality of submodules arranged on the transparent insulating panel . Each of the submodules has a bus bar electrode on the back electrode layer along both sides to take out its output current, and an electrical connection between the sub modules is to connect a connecting lead between the bus bar electrodes. The translucent thin film solar cell module according to claim 1 , wherein the translucent thin film solar cell module is performed. One or more translucent thin-film solar cell submodules having a predetermined translucency and one or more non-transparent thin-film solar cell submodules are disposed on the same transparent insulating panel. A module,
Each of the translucent submodule and the non-translucent submodule includes a transparent electrode layer, a semiconductor photoelectric conversion layer, and a back electrode layer that are sequentially laminated on a transparent insulating substrate,
The translucent submodule further includes a plurality of translucent grooves or holes penetrating the semiconductor photoelectric conversion layer and the back electrode layer,
The ratio of the number of the translucent submodules to the non-translucent submodule is set so that a desired average translucency can be obtained as the entire translucent module ,
Each of the sub-modules has a bus bar electrode on the back electrode layer along both sides to take out its output current,
The electrical connection between these submodules is made by joining connection leads between the bus bar electrodes,
A translucent thin film solar cell module , wherein an insulating film is inserted between a position where the connection lead directly faces the back electrode layer and a position facing an adjacent region between the submodules . 4. The translucent thin film solar cell module according to claim 3 , wherein a back side of the back electrode layer is sealed by the transparent insulating panel through a transparent sealing resin layer. The translucent submodule and the non-translucent submodule are electrically connected to each other so 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: Predetermined plurality of said sub-modules comprises a plurality of electrically parallel-connected parallel submodule groups, claim 1, the plurality of parallel sub-module group is characterized by being electrically connected in series 5 The translucent thin film solar cell module according to any one of the above. The translucent thin film solar cell module according to claim 6 , wherein the plurality of parallel submodule groups include the same number of translucent submodules. The translucent submodule and the non-translucent submodule are arranged in a predetermined periodic pattern on the panel so that the illumination effect by the transmitted light of the entire translucent module is uniform. thin film solar module according to any one of claims 1 to 7, characterized in that.

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