JP3972233B2 - Solar cell module - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solar cell module having a thin-film solar cell using a flexible substrate, and more particularly to the configuration of wiring for extracting power.
[0002]
[Prior art]
Currently, clean energy research and development is underway from the standpoint of environmental protection. Among them, solar cells are attracting attention because their resources (sunlight) are infinite and pollution-free.
[0003]
Thin-film solar cells are expected to become the mainstream of solar cells in the future because they are thin and lightweight, inexpensive to manufacture, and easy to increase in area, and are attached to roofs and windows of buildings in addition to power supply. Demand is also expanding for commercial and general residential use.
[0004]
Conventional thin-film solar cells have used glass substrates, but research and development of flexible solar cells using plastic films and metal films has been promoted in terms of weight reduction, workability, and mass productivity. Taking advantage of this flexibility, mass production became possible by a roll-to-roll method or a stepping roll method.
[0005]
In the above thin film solar cell, a first electrode (hereinafter also referred to as a lower electrode), a photoelectric conversion layer comprising a thin film semiconductor layer, and a second electrode (hereinafter also referred to as a transparent electrode) are laminated on a flexible electrically insulating film substrate. A plurality of photoelectric conversion elements (or cells) thus formed are formed. By repeating electrically connecting the first electrode of a certain photoelectric conversion element and the second electrode of the adjacent photoelectric conversion element, the first electrode of the first photoelectric conversion element and the second electrode of the last photoelectric conversion element Can output the voltage required for For example, in order to obtain an alternating current of 100 V as a commercial power source by alternating current with an inverter, the output voltage of the thin-film solar cell is desirably 100 V or higher, and actually several tens or more elements are connected in series.
[0006]
Such a photoelectric conversion element and its series connection are formed by forming an electrode layer and a photoelectric conversion layer, patterning each layer, and a combination procedure thereof. As the patterning, laser patterning or lift-off patterning is used. The structure of a thin-film solar cell in which a small number of photoelectric conversion elements are connected in series and the outline of the manufacturing method will be described below (see JP-A-10-233517).
[0007]
FIG. 9 shows an example of a thin film solar cell described in the above-mentioned patent application specification, (a) is a plan view, (b) is a cross-sectional view taken along lines ABCD and BQC in (a), c) shows an EE cross-sectional view in (a).
[0008]
A first electrode layer, a photoelectric conversion layer, and a second electrode layer are sequentially laminated on a long film substrate made of an electrically insulating and flexible resin, and a third electrode layer is formed on the opposite side (back surface) of the film substrate. The fourth electrode layer is laminated to form a back electrode. The photoelectric conversion layer is, for example, an amorphous silicon pin junction. As the film substrate material, for example, a polyimide film is used.
[0009]
Next, the outline of the manufacturing process will be described below.
[0010]
First, using a punch in the film substrate, a connection hole h1 is opened, and a silver film is formed by sputtering as a first electrode layer on one side (front side) of the substrate, and on the opposite side (back side). Similarly forms a silver electrode as the third electrode layer. The first electrode layer and the third electrode layer overlap with each other on the inner wall of the connection hole h1, and are electrically connected.
[0011]
After the film formation, on the front side, the first electrode layer is laser processed into a predetermined shape, and the lower electrodes 11 to 16 are patterned. Adjacent portions of the lower electrodes l1 to l6 form one separation line g2, and two separation lines g2 are formed for separation between the two series-connected photoelectric conversion elements and the peripheral conductive portion f. The electrodes l1 to l6 are surrounded by a separation line. After using the punch again to open the current collecting hole h2, an a-Si layer as a photoelectric conversion layer p is formed on the front side by plasma CVD. A film having a width W2 is formed using a mask, and the same separation line as that of the first electrode layer is formed only between the two-row elements by laser processing.
[0012]
Further, a transparent electrode layer (ITO layer) is formed on the front side as the second electrode layer. However, a mask is applied between the two element rows and on both side edges of the substrate parallel to the element row so as not to form the film in the connection hole h1, and the film is formed only on the element part. Next, a silver electrode is formed as a fourth electrode layer on the entire back surface. By forming the fourth electrode, the second electrode and the fourth electrode overlap with each other on the inner wall of the current collecting hole h2, and are brought into conduction. On the front side, separation lines having the same pattern as the lower electrode are formed by laser processing to form individual second electrodes u1 to u6, and on the back side, the third electrode and the fourth electrode are simultaneously laser processed to provide connection electrodes e12 to e56. In addition, the power extraction electrodes o1 and o2 are individualized, the separation line g2 is formed so as to overlap the front-side separation line g3 at the periphery of the substrate, and a single separation line is formed between the adjacent electrodes.
[0013]
There is a separation line g3 at the periphery that encloses all the thin-film solar cell elements in a lump and the adjacent boundary between the two rows of series-connected solar cell elements (inside the peripheral conductive part f). There are no layers in the separation line g3. On the back side, there is a separation line g2 (inside the peripheral conductive portion f) at the peripheral edge that encloses all the electrodes together and at the adjacent boundary of the two rows of series connection electrodes. There are no layers in the separation line g2.
[0014]
In this way, power extraction electrode o1-collection hole h2-upper electrode u1, photoelectric conversion layer, lower electrode l1-connection hole h1-connection electrode e12-upper electrode u2, photoelectric conversion layer, lower electrode l2-connection electrode e23- -The series connection of the photoelectric conversion elements in the order of the upper electrode u6, the photoelectric conversion layer, the lower electrode l6-the connection hole h1-the power extraction electrode o2 is completed.
[0015]
Since the third electrode layer and the fourth electrode layer are electrically at the same potential, in the following description, for convenience of explanation, they may be treated as a single connection electrode layer.
[0016]
FIG. 10 is a perspective view showing a simplified configuration of the flexible thin film solar cell. The unit photoelectric conversion element 62 formed on the front surface of the substrate 61 and the connection electrode layer 63 formed on the back surface of the substrate 61 are each completely separated into a plurality of unit units, and are formed by shifting the separation positions. For this reason, the current generated in the photoelectric conversion layer 65 which is an amorphous semiconductor portion of the element 62 is first collected in the transparent electrode layer 66 and then through the current collecting hole 67 (h2) formed in the transparent electrode layer region. And transparent to the element adjacent to the element through a connection hole 68 (h1) for series connection formed in the connection electrode layer 63 and outside the transparent electrode layer area of the element. The lower electrode layer 64 extending to the outside of the electrode layer region is reached, and both elements are connected in series.
[0017]
The solar cell as described above is configured as a solar cell module including a wiring for power extraction. However, since this module is installed outdoors, it is integrated with the wiring for power extraction with ethylene vinyl acetate (EVA). Further, it is sealed with a protective sheet such as a moisture-proof film such as ethylene / tetrafluoroethylene copolymer (ETFE) or cycloolefin polymer (CPE). The power extraction wiring is composed of a main wiring for connecting to the outside of the module and a sub wiring for connecting the main wiring and one or a plurality of solar cells. Since the solar battery cell is configured to extract power from the back electrode on the side opposite to the light receiving surface, the sub wiring is connected to the back electrode.
[0018]
FIG. 7 is a plan view showing a configuration of an example of a conventional flexible solar cell module, and FIG. 8 is a cross-sectional view taken along line Y1-Y1 of FIG. FIG. 6 is a simplified view of the essential parts of FIGS. 7 and 8 for convenience of explanation of the present invention.
[0019]
In the solar cell module 40 shown in FIGS. 7 and 8, a plurality of solar cell elements 41 are arranged in one direction. The number and arrangement of solar cell elements vary depending on the required specifications of the solar cell module. On both sides of each solar cell element 41, main wirings 42 and 43 are arranged so as to be parallel to each other. Both electrodes of each solar cell element 41 are connected to main wirings 42 and 43 via conductive adhesive tapes 41a and 41b as sub wirings, respectively.
[0020]
The solar cell element 41, the conductive adhesive tapes 41a and 41b, and the electrode wirings 42 and 43 are sealed with a filler 44 that is a heat-fusible plastic material such as EVA. Specifically, the solar cell element 41, the conductive adhesive tapes 41a and 41b as the secondary wirings, and the main wirings 42 and 43 are arranged on the lower filler sheet 441, and the upper filler sheet from above is arranged. 442 is mounted and integrally formed by heat-sealing. Further, on the upper surface and the lower surface of the filler 44, surface protective materials 45 and 46 using a fluorine-based film material such as ETFE are provided as a weather resistant film.
[0021]
Further, the solar cell module 41 is provided with terminal portions 47 and 48 for taking out electric power connected to the respective one end portions of the main wirings 42 and 43. These terminal portions 47 and 48 are connected to a power cable (not shown), take out the electric power generated by each solar cell element 41, and send it out to a power converter installed indoors.
[0022]
In the simplified FIG. 6, a solar cell 31 including a plurality of solar cell elements, a main wiring 42 disposed in a non-power generation area outside the power generation area (hatched portion) 30, and subwirings 41 a and 41 b Only the protective layer 33 provided on both the light-receiving surface side and the non-light-receiving surface side of the solar cell is conceptually shown.
[0023]
[Problems to be solved by the invention]
By the way, in the conventional solar cell module, as described above, a conductive tape to be a sub-wiring is pasted on the back electrode corresponding to the electrode of the solar cell element, and the other side of the tape is pasted on the main wiring. The extraction wiring is configured. When the connection between the back electrode and the sub-wiring is performed by soldering, the reliability of the connecting portion is better than when the conductive tape is used. Since the thin film photoelectric conversion layer on the back side of the connection surface is damaged due to mechanical stress, a method of applying a conductive tape as described above is employed.
[0024]
However, the method using a conductive tape has the following problems. Since this method has a limited contact area, there is a problem that reliability as an electrical contact portion is low as compared with soldering. Further, it is necessary to use a thin conductive tape for flexibility, but there is a problem that the tape itself is vulnerable to thermal and mechanical stress. Further, there is a problem that automation is difficult because handling in manufacturing is difficult. Furthermore, as an external problem, there are some problems such as that wiring is visible through EVA or ETFE, so that a process / step for hiding the wiring is necessary.
[0025]
The present invention has been made to solve the above-described problems, and an object of the present invention is to simplify the structure of the wiring so that the reliability as an electrical connection portion is electrically and mechanically. An object of the present invention is to provide a solar cell module that is high and easy to handle in manufacture.
[0026]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a photoelectric conversion unit in which a lower electrode layer, a photoelectric conversion layer, and a transparent electrode layer, which are metal electrodes, are sequentially stacked on the surface of an electrically insulating flexible substrate, and the substrate A connecting electrode layer formed on the back surface of the substrate, wherein the photoelectric conversion portion and the connecting electrode layer are separated from each other in unit parts by shifting their positions, and for electrical series connection formed outside the transparent electrode layer forming region. A thin-film solar cell in which adjacent unit photoelectric conversion portions separated from each other on the surface are electrically connected in series via a connection hole and a current collecting hole formed in the transparent electrode layer forming region; In order to seal this solar cell with an electrically insulating protective material, a protective layer is provided on both the light-receiving surface side and the non-light-receiving surface side of the solar cell, and this protective layer extends to the side of the solar cell. A non-power generation area is formed and allocated to this non-power generation area. And extended positive and negative two poles of the main wiring and the said connection electrode layer electrically connected configured to draw power to the outside, the front SL connection electrode layer formed on the back surface of the substrate to the non-power generation region In the solar cell module formed and electrically connected to the extension portion of the connection electrode layer and the main wiring ,
The extension portion of the connection electrode layer and the main wiring are connected by filling and welding with conductive paste or solder to through holes formed in the extension portion of the connection electrode layer at a plurality of locations on the main wiring. (Claim 1).
[0027]
In the extended portion of the connection electrode layer (back electrode), the electrode metal is laminated on the entire film substrate surface, and if necessary, by conducting laser patterning or lift-off patterning in the same manner as patterning of the solar cell element, Forming a non-conductive portion. A part of the back electrode is opposed to the solar cell element via the film substrate, but most of the other back surface is a free surface that does not face the solar cell element. Even if thermal or mechanical stress such as soldering or pressure bonding is applied to this surface, the solar cell element is not damaged. Therefore, connection for wiring is easy and reliability is improved. In addition, by connecting with conductive paste or solder filling and welding to the through hole formed in the extended part of the connection electrode layer, the electrical connection part is highly reliable both electrically and mechanically and manufactured The above handling becomes easy .
[0028]
In the above, the protective layer includes at least a protective layer made of an organic material adhesive such as ethylene vinyl acetate (EVA), an ethylene / tetrafluoroethylene copolymer (ETFE), and a cycloolefin polymer (CPE). A protective layer made of a moisture-proof film such as the above is provided (claim 2). Thereby, the electrical connection part is protected mechanically and electrically, and the solar cell module excellent in weather resistance can be comprised.
[0029]
Further, the main wiring, and shall use copper tape, tinned copper tape, any of a solder-plated copper tape (claim 3).
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Based on the drawings, embodiments of the present invention will be described below.
[0031]
FIG. 1 relates to an embodiment of the present invention, and similarly to FIG. 6, a solar cell 31 including a plurality of solar cell elements 60 a and a main wiring 42 disposed in a non-power generation region outside the power generation region (hatched portion). Only the extended portion 50 of the connection electrode layer and the protective layer 33 provided on both the light receiving surface side and the non-light receiving surface side of the solar cell are shown. In this embodiment, the plurality of solar cell elements 60a are arranged in parallel with the main wiring 42, and are connected in series, for example, with the right side in the figure as the positive electrode and the left side as the negative electrode.
[0032]
FIG. 3 shows an example of an embodiment of electrical connection between the main wiring 42 and the extended portion 50 of the connection electrode layer in FIG. 1, both of which are conductive adhesives interposed in the longitudinal direction of the main wiring 42. It is connected through the agent 49. The conductive adhesive 49 may be interposed over the entire longitudinal direction of the main wiring 42, but workability is better when it is partially interposed. Copper tape, tin-plated copper tape, or solder-plated copper tape is used for the main wiring. Instead of the conductive adhesive, a conductive paste or a conductive double-sided pressure-sensitive adhesive tape can be used.
[0033]
FIG. 2 shows an embodiment of a solar cell module different from FIG. The difference from FIG. 1 is that a plurality of solar cell elements 60b are arranged at right angles to the main wiring 42 and that the non-conductive portion 50c is patterned on the extended portion 50a of the connection electrode layer. . The series connection of the solar cells starts from the lower right portion 51a in the extended portion 50a of the connection electrode layer, is connected in series from the lower right solar cell element to the upper right solar cell element, and then immediately on the left upper solar cell element. And is connected in series to the lower element, and is sequentially connected up and down, and finally connected to the lower left portion 51b in the extension portion of the left connection electrode layer via the lower left solar cell element. .
[0034]
FIG. 4 shows an enlarged view of the extension portion 50a of the connection electrode layer in FIG. In the embodiment of FIG. 2, as shown in FIG. 4, conductive paste is formed as shown in FIG. 5 with respect to the through holes 52 formed in the extended portions of the connection electrode layer at a plurality of locations on the main wiring. Alternatively, by filling and welding the solder 53, the extension portion 50a of the connection electrode layer and the main wiring are connected. As a result, a highly reliable connection can be obtained both electrically and mechanically.
[0035]
【The invention's effect】
According to the present invention, as described above, the photoelectric conversion portion formed by sequentially laminating the lower electrode layer, the photoelectric conversion layer, and the transparent electrode layer, which are metal electrodes, on the surface of the electrically insulating flexible substrate, and the back surface of the substrate A connecting hole for electrical series connection formed outside the transparent electrode layer formation region, wherein the photoelectric conversion part and the connecting electrode layer are separated from each other and separated into unit parts. And a thin-film solar cell in which adjacent unit photoelectric conversion portions separated from each other on the surface are electrically connected in series via current collecting holes formed in the transparent electrode layer forming region. In order to seal the solar cell with an electrically insulating protective material, a protective layer is provided on both the light-receiving surface side and the non-light-receiving surface side of the solar cell, and this protective layer extends to the side of the solar cell to prevent non-power generation. A positive region disposed in this non-power generation region. 2-pole main wiring and the said connection electrode layer electrically connected configured to take out the power to the external, the connection electrode layer formed on the back surface of the front Stories substrate formed extended to the non-power generation region In the solar cell module in which the extension portion of the connection electrode layer and the main wiring are electrically connected, the extension portion of the connection electrode layer and the main wiring are a plurality of locations on the main wiring, and the connection electrode layer By connecting with conductive paste or solder filling and welding to the through hole formed in the extended part of the wiring, the structure of the wiring is simplified, and the reliability as an electrical connection part is also electrically It is possible to provide a solar cell module that is mechanically high and easy to manufacture.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a main part of a solar cell module according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a main part of a solar cell module according to another embodiment of the present invention. FIG. 4 is a connection configuration diagram using a through hole. FIG. 5 is an enlarged view of a through hole portion. FIG. 6 is a schematic configuration diagram of a main part of a conventional solar cell module. 8 is a cross-sectional view taken along line Y1-Y1 of FIG. 7. FIG. 9 is a diagram showing an example of the configuration of the thin film solar cell. FIG. 10 is a perspective view of the thin film solar cell.
30: Power generation region, 31: Solar cell, 33: Protective layer, 42: Main wiring, 49: Conductive adhesive, 50, 50a: Extension part of connection electrode layer, 50c: Non-conductive part, 52: Through hole, 53 : Conductive paste or solder, 60a, 60b: solar cell element.

Claims (3)

A photoelectric conversion part formed by sequentially laminating a lower electrode layer, a photoelectric conversion layer, and a transparent electrode layer, which are metal electrodes, on the surface of an electrically insulating flexible substrate, and a connection electrode layer formed on the back surface of the substrate, The photoelectric conversion part and the connection electrode layer are shifted from each other and separated into unit parts, and formed in the connection hole for electrical series connection formed outside the transparent electrode layer formation region and in the transparent electrode layer formation region A thin-film solar cell in which adjacent unit photoelectric conversion portions separated from each other on the surface are electrically connected in series via the current collecting holes, and the solar cell is electrically insulated by a protective material. In order to seal, a protective layer is provided on both the light-receiving surface side and the non-light-receiving surface side of the solar cell, and this protective layer extends to the side of the solar cell to form a non-power generation region. Main wiring of positive and negative polarity arranged in the region and the connection electrode layer The electrically connected configured to draw power to the outside, the front SL connection electrode layer formed on the back surface of the substrate and formed to extend to the non-power generation region, and the main wiring extending portion of the connection electrode layer In a solar cell module formed by electrically connecting
The extension portion of the connection electrode layer and the main wiring are connected by filling and welding with conductive paste or solder to through holes formed in the extension portion of the connection electrode layer at a plurality of locations on the main wiring. A solar cell module.   2. The protective layer according to claim 1, wherein the protective layer comprises at least a protective layer made of an organic material adhesive such as ethylene vinyl acetate (EVA), an ethylene-tetrafluoroethylene copolymer (ETFE), a cycloolefin polymer (CPE). A solar cell module comprising a protective layer made of a moisture-proof film.   3. The solar cell module according to claim 1, wherein the main wiring is any one of a copper tape, a tin-plated copper tape, and a solder-plated copper tape.

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