JPH07302923A - Photovoltaic device - Google Patents

Abstract

PURPOSE:To obtain a photovoltaic crevice which is enhanced in durability and reliability in outdoor use by a method wherein the lead wire of a bypass diode as a flat diode is formed of metal foil, and the bypass diode and tire metal foil are connected together through the intermediary of a connecting material. CONSTITUTION:A bypass diode 113 installed on a photovoltaic device is a flat diode, and the lead wire 112 of the bypass diode 113 is formed of two pieces of metal foil. The bypass diode 113 and the lead wire 112 are connected together through a connecting material 111. By this setup, when a photovoltaic device is sealed in with filler such as EVE, a phenomenon that only the filter covering the bypass diode 113 protrudes from the surface is eliminated, and the photovoltaic device is improved in flatness when it is turned into a module. Even if stress is applied to a joint due to bending when a photovoltaic device module is deflected, it can be relaxed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic element used in a solar cell module or the like.

[0002]

In recent years, and global warming due to the increase in the greenhouse effect that is CO ₂ becomes a problem, demand for clean sources of energy development that do not emit CO _2, has been increasingly.

Nuclear power generation, which is one of such energy sources, has not solved the problem of radioactive waste.
A safer and cleaner energy source is desired.

Among the clean energy sources that are expected in the future, solar cells have received a great deal of attention because of their cleanliness, safety and ease of handling.

Among various solar cells, the amorphous silicon solar cell has a conversion efficiency which is lower than that of a crystalline solar cell, but it is easy to make a large area and has a large light absorption coefficient so that it can operate as a thin film. This is one of the promising solar cells for the future because it has excellent features not found in crystalline solar cells.

[0006] Normally, a solar cell for a battery is used by connecting a plurality of solar cells in series because the output voltage is insufficient with only one solar cell.

However, the above-mentioned configuration in which a plurality of cells are connected in series to operate has the following problems. When a part of the cell is blocked from sunlight due to the shadow of a building or snow and it stops generating electricity, the total generated voltage from other elements that are generating electricity normally becomes reverse voltage to each element. It is applied directly. When the reverse voltage exceeds the breakdown voltage of the element, the element is more likely to be destroyed. In order to avoid this, a method is known in which, for each element connected in series, a diode is connected in parallel with the element in the opposite direction.

FIG. 6 (a) is a schematic view of a connection form in a conventional solar cell module. This is an example in which three solar cell elements are connected in series and then a bypass diode is connected. Further, FIG. 6B is a cross-sectional view of a portion XX ′ in FIG.

In the solar cell element 600 shown in FIG. 6, a lower electrode layer 602 is formed on a substrate 601, a semiconductor layer 603 is formed on the lower electrode layer 602, and an upper electrode layer 604 is formed on the semiconductor layer 603. It was made by stacking.

Further, a collecting electrode 606 which is a collecting electrode of the upper electrode 604 is formed on the surface of the upper electrode 604, and then a bus bar electrode 607 which is a further collecting electrode of the collecting electrode 606 is attached to the collecting electrode 606. It's on top. Further, the collector electrode 606 and the bus bar electrode 607 are electrically connected with a conductive adhesive 608, so that an extraction electrode from the upper electrode layer 604 is manufactured.

On the other hand, the extraction electrode from the lower electrode layer 602 is formed by spot welding a metal body 611 such as copper to a portion 610 where a part of the conductive substrate in the solar cell element 600 is exposed by a mechanical method. It is manufactured by connecting by a method such as soldering.

Next, the bus bar electrode 607 of one solar cell element 600 and the metal body 611 which is an extraction electrode from the substrate of the solar cell element adjacent thereto are connected using a copper foil (connection member). As a result, each solar cell element is electrically serialized. Further, in each solar cell element 600, the bypass diode 630 is provided between the bus bar electrode 607 and the metal body 611 drawn out from the conductive substrate.
It is connected by soldering or the like. The solar cell module is completed by the above respective connections.

However, the above-described solar cell module has the following two problems.

(1) The method of individually connecting the connecting member and the bypass diode is complicated in work and difficult to mass-produce.

(2) Generally available bypass diodes have a relatively large shape because they have a cover resin and a cylindrical lead wire around them. For this reason, when the solar cell element is encapsulated with a filler such as EVA (ethylene vinyl acetate) in a later step, only the bypass diode portion rises from the surface, and the flatness of the solar cell module deteriorates.

A method for solving the above problems is disclosed in a publicly known material (Japanese Patent Laid-Open No. 5-291602), the contents of which are as follows.

(1) A flat diode (chip diode) having a relatively small thickness is used as the bypass diode.

(2) A member in which a wiring material for connecting each solar cell element in series and the bypass diode described above are alternately connected is prepared in advance. (3) The solar cell module is manufactured by connecting the solar cell elements using the member of (2).

FIG. 7 is a schematic view for explaining a connection form of the above solar cell module.

FIG. 7A is a plan view in which three solar cell elements are arranged, and FIG. 7B is a plan view of a member in which a wiring material for series connection and a bypass diode are connected in advance. FIG. 7C is a plan view when the respective solar cell elements of FIG. 7A and the members of FIG. 7B are connected.

The solar cell element 300 shown in FIG. 7 is formed by sequentially stacking a lower electrode layer, a semiconductor layer and an upper electrode layer on a conductive substrate. In these solar cell elements, in order to completely electrically separate the upper electrode layer and the lower electrode layer, a part 706 of the upper electrode layer is removed, and then the upper electrode surface is covered with a collecting electrode of the upper electrode. Certain collector electrode 7
01 is produced.

Next, a bus bar electrode 702 which is a further collecting electrode of the collecting electrode 701 is placed on the collecting electrode 701, and then the collecting electrode 701 and the bus bar electrode 702 are electrically connected by a conductive adhesive 707. By doing so, an extraction electrode is obtained from the upper electrode layer.

Further, in order to ensure the electrical separation between the bus bar electrode 702 and the conductive substrate, the solar cell element 700.
The insulating tape 7 is provided between the end of the
09 is provided.

On the other hand, for electrical extraction from the lower electrode, a metal body 703 such as copper is spot-welded on the exposed portion 708 of the conductive substrate of the solar cell element 700. It is done by connecting with.

Further, the bypass diode 710 and the metal body 711 for series connection are connected in advance as shown in FIG. 7B, placed as shown in FIG. 7C, and electrically connected by soldering or welding. Connected.

When the above method is used, since the serial connection member and the bypass diode have an integral structure, they can be manufactured in separate steps in advance, and the work steps can be simplified. Therefore, a mass production line can be constructed. It became easier to peel.

[0027]

Since the solar cell module connected as described above is usually used outdoors such as on the roof of a building, it is exposed to wind and rain every day and constantly receives external stress. . That is, the solar cell module is bent each time a stress is applied, and as a whole, it receives repeated bending stress for many years. Further, the amount of deflection is more remarkable in a solar cell module using a flexible substrate such as stainless steel, which has flexibility against external stress.

When subjected to repeated bending stress for a long period of time, the stress concentrates on the series connection member and the bypass diode portion in the solar cell module. The problems that occur at this time are shown below.

(1) Due to the deformation of the series connection member, cracks, breaks, etc. occur and the solar cell characteristics deteriorate.

(2) The bypass diode is cracked and the diode characteristics are destroyed.

(3) The connection part (mainly solder) between the bypass diode and the series connection member is disengaged, resulting in a contact failure state.

An object of the present invention is to solve the above problems by providing a solar cell module that is inexpensive, easy to manufacture, and highly reliable.

[0033]

The photovoltaic element of the present invention is a photovoltaic element in which at least one bypass diode is installed for each photovoltaic element, and the bypass diode is a flat diode. The lead wire of the bypass diode is made of two metal foil materials, and the bypass diode and the metal foil material are connected via a connecting material.

In the photovoltaic element of the present invention, at least one of the metal foil members has a protrusion, and a plurality of photovoltaic elements are connected using the protrusion. Characterize.

Further, in the photovoltaic element of the present invention, at least one of the metal foil materials has both a cut and a protrusion, and a plurality of photovoltaics are formed by using the protrusion. It is characterized in that the elements are connected.

Further, the photovoltaic element of the present invention is characterized in that the protrusions of the all-purpose foil material are used for connection.

The photovoltaic element of the present invention is characterized in that the metal foil material has a Vickers hardness of 70 or less.

[0038]

In the present invention, since the bypass diode is a flat diode (chip diode) having a relatively small thickness, the photovoltaic element is encapsulated by using a filling material such as EVA (ethylene vinyl acetate) in the subsequent process. In this case, the phenomenon that only the part of the bypass diode rises from the surface disappears, and the planarity when the photovoltaic element is modularized is improved.

At the same time, according to the present invention, the lead wire of the bypass diode is made of two metal foil materials, and the bypass diode and the metal foil material are connected to each other through the connecting material. Even when the module is bent and the connecting portion is stressed by bending, the stress can be relaxed.

Furthermore, in the present invention, at least one of the metal foil members has a protrusion, and a plurality of photovoltaic elements are connected using this protrusion, so that the metal foil material is directly connected. Since the stress is dispersed in the protruding portion, the stress applied to the bypass diode portion can be reduced, and breakage such as cracking does not occur. Furthermore, since the width of the metal foil material part becomes thicker,
The strength of the foil material itself against pulling and bending increases, and the metal foil material is less likely to crack or break.

Further, in the present invention, at least one of the metal foil materials has both a notch and a protrusion, and a plurality of photovoltaic elements are connected using the protrusion. As a result, the cut portion serves as a stress loop to absorb the stress, so that the stress applied to the bypass diode portion can be reduced.

Further, according to the present invention, in both of the above-described modes, the effect is further recognized because the mechanical strength is increased by fixing the protruding portion for connection.

Finally, in the present invention, by using a very soft material having a Vickers hardness of 70 or less as the metal foil material, the tenacity of the metal foil material itself against repeated bending increases, so that the strength of the metal foil against breaking is increased. Increase.

[0044]

Embodiments Embodiments of the present invention will be described below with reference to FIG.

FIG. 1 is a schematic view for explaining the connection form of the solar cell module of the present invention.

FIG. 1A is a plan view in which three solar cell elements are arranged, and FIG. 1B is a plan view of a member in which a wiring material for series connection and a bypass diode are connected in advance. FIG. 1C is a plan view when the respective solar cell elements of FIG. 1A and the members of FIG. 1B are connected. In addition, FIG. 1D is a cross-sectional view of a portion XX ′ in FIG.

The solar cell element 100 shown in FIG. 1 comprises a lower electrode layer 102, a semiconductor layer 103, and an upper electrode layer 104, which are sequentially laminated on a conductive substrate. In these solar cell elements, in order to completely electrically separate the upper electrode layer and the lower electrode layer, after removing a part 105 of the upper electrode layer, a collector electrode of the upper electrode is formed on the surface of the upper electrode. A collector electrode 106 is produced.

Next, a bus bar electrode 107, which is a further collecting electrode of the collecting electrode 106, is placed on the collecting electrode 106, and then the collecting electrode 106 and the bus bar electrode 107 are electrically connected by a conductive adhesive 108. By doing so, an extraction electrode is obtained from the upper electrode layer.

Further, in order to ensure the electrical separation between the bus bar electrode 107 and the conductive substrate, the solar cell element 100
The insulating tape 1 is provided between the end of the
09 is provided.

On the other hand, electrical extraction from the lower electrode is carried out by a method such as spot welding with a metal body 111 such as copper on the exposed portion 110 of the conductive substrate of the solar cell element 100. It is done by connecting with.

Further, the bypass diode 113 and the metal body 111 for serial connection are connected in advance as shown in FIG. 1 (b).

Next, the solar cell element of FIG.
The bypass diode member of (b) is placed as shown in FIG. 1 (c) and electrically connected by a method such as soldering or welding.

(Bypass Diode) The type, performance, size and shape of the bypass diode used in the present invention are as follows.
The size varies depending on the size of the solar cell element, the current used, the connection form, etc., but is not particularly limited. However, considering the planarity of the solar cell, it is preferable that the shape is as small as possible and the thickness is thin. That is, a chip diode or a flat diode is more preferable.

(Metal Foil Material) When selecting a metal foil material used also for the lead wire of the bypass diode used in the present invention, it is necessary to consider the following three points.

(1) This is the current path portion.

(2) I want to solder.

(3) A die is desired to be manufactured by the punching method.

Therefore, it is possible to use a metal such as silver, copper, tin, lead or nickel which has good conductivity, can be soldered and is easy to process, but is not limited to this.
A plated metal such as silver-plated copper or solder-plated copper may be used. Further, the shape is not particularly limited, and the protrusion may be located anywhere, and there is no problem if the protrusion is provided on both of the two metal foil materials.

(Solar Cell Element) The solar cell element used in the present invention can be suitably applied to an amorphous silicon solar cell which is desired to have flexibility.
However, the same configuration can be applied to a solar cell using a single crystal silicon type, a polycrystalline silicon type, or a semiconductor other than silicon other than an amorphous type, and a Schottky junction type solar cell.

(Substrate) The substrate 101 is a member that mechanically supports the semiconductor layer and is also used as an electrode in the case of a thin film solar cell such as amorphous silicon. Therefore, the base 101 is required to have heat resistance to withstand the heating temperature when the semiconductor layer 103 is formed, but may be conductive or electrically insulating.

As the conductive material, for example, Fe, N
i, Cr, Al, Mo, Au, Nb, Ta, V, Ti,
Metals such as Pt and Pb or alloys thereof, such as brass
, Stainless steel and other thin plates and their composites and carbon sheets
Sheet, galvanized steel sheet. In addition, electrically insulating material
As the material, polyester, polyethylene, polycarbonate
Nate, cellulose acetate, polypropylene, poly
Vinyl chloride, polyvinylidene chloride, polystyrene, poly
Heat resistant synthetic resin such as amide, polyimide, epoxy, etc.
Film or sheet or these and glass fiber,
With carbon fiber, boron fiber, metal fiber, etc.
Table of composites, thin plates of these metals, resin sheets, etc.
Metallic thin film and / or SiO of different materials on the surface₂, Si₃N
_Four, Al₂O ₃, Insulating thin film such as AlN is sputtered
The surface coating treatment was performed by the coating method, the plating method, etc.
And glass, ceramics, and the like.

(Lower Electrode) The lower electrode 102 is one electrode for taking out electric power generated in the semiconductor layer, and is required to have a work function that makes an ohmic contact with the semiconductor layer. Examples of the material include Al, Ag, Pt, Au, Ni, Ti, Mo, Fe,
V, Cr, Cu, stainless steel, brass, nichrome, S
So-called simple metals or alloys such as nO ₂ , In ₂ O ₃ , ZnO and ITO, and transparent conductive oxides (TCO) are used. The surface of the lower electrode 102 is preferably smooth, but in the case of causing diffuse reflection of light, the surface may be textured. Further, when the substrate 101 is conductive, the lower electrode 102 need not be provided.

As a method of manufacturing the lower electrode, for example, a method such as plating, vapor deposition, sputtering or the like is used.

(Semiconductor Layer) As the semiconductor layer 103, known semiconductor materials generally used for thin film solar cells can be used. Examples of the semiconductor layer of the solar cell element used in the present invention include a pin junction amorphous silicon layer, a pn junction polycrystalline silicon layer, and CuInSe ₂ / C.
A compound semiconductor layer such as dS may be used. As a method for manufacturing the semiconductor layer, when the semiconductor layer is an amorphous silicon layer, it can be manufactured by introducing a raw material gas such as silane gas that forms a thin film into plasma CVD or the like for generating plasma discharge. . When the semiconductor layer is a pn junction polycrystalline silicon layer, for example, there is a method of forming a thin film from molten silicon. In addition, the semiconductor layer is CuIn
In the case of Se ₂ / CdS, it is formed by a method such as an electron beam vapor deposition method, a sputtering method, and an electrodeposition method.

(Upper Electrode) The upper electrode 104 is an electrode for taking out the electromotive force generated in the semiconductor layer and is paired with the lower electrode 102. Upper electrode 104
Is necessary in the case of a semiconductor having a high sheet resistance such as amorphous silicon, and is not particularly necessary in a crystalline solar cell since the sheet resistance is low. Also, the upper electrode 1
Since 04 is located on the light incident side, it needs to be transparent and is sometimes called a transparent electrode. Upper electrode 104
Has a light transmittance of 85% or more in order to efficiently absorb light from the sun or a white fluorescent lamp into the semiconductor layer. Furthermore, electrically, a current generated by light is applied to the semiconductor layer. On the other hand, it is desirable that the sheet resistance value is 100Ω / □ or less so that the sheet flows in the lateral direction. Examples of materials having such characteristics include SnO ₂ and In ₂
O ₃ , ZnO, CdO, CdSnO ₄ , ITO (In ₂ O ₃
+ SnO ₂ ) and other metal oxides.

(Collecting Electrode) The collecting electrode 106 is generally formed in a comb shape, and a suitable width and pitch are determined from the sheet resistance values of the semiconductor layer and the upper electrode. The collector electrode is required to have a low specific resistance so as not to be a series resistance of the solar cell, and a preferable specific resistance is 10 ^-2 Ωcm to 10 ^-6 Ωc.
m. Examples of the material of the collector electrode include Ti and C
Metals such as r, Mo, W, Al, Ag, Ni, Cu, Sn and Pt, or alloys or solders thereof are used. Generally, a metal paste in which a metal powder and a polymer resin binder are in a paste form is used, but it is not limited to this.

(Bus Bar Electrode) The bus bar electrode 107 is
This is an electrode for further collecting the current flowing through the collector electrode 106 at one end. As the electrode material, for example, Ag, Pt, C
A metal such as u or an alloy thereof can be used, and a wire-shaped or foil-shaped one is attached as a form. As the foil, for example, a copper foil, or a copper foil tin-plated, and in some cases, an adhesive is used.

[0068]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

Example 1 In this example, a case of an amorphous silicon solar cell using a stainless steel substrate as a base will be specifically described.

As the stainless steel substrate, a 0.1 mm-thick stainless steel foil having a cleaned surface was used. On this stainless steel foil, as a lower electrode, 500
The ZnO film of 0 Å has a substrate temperature of 350 by the sputtering method.
Made at ° C.

Next, on the surface of the ZnO film, a pin-junction semiconductor layer composed of the three layers shown in Table 1 was formed as a photoelectric conversion layer. The substrate temperature at this time is 250 for all three layers.
The temperature was maintained at 0 ° C, and three layers were continuously produced.

[0072]

[Table 1] Further, on the semiconductor layer, as the upper electrode layer 104, 70
The ITO transparent electrode film of 0 Å has a base temperature of 2 under oxygen atmosphere.
It was produced by resistance heating vapor deposition of In and Sn at 00 ° C.

The rolled stainless steel substrate on which the multilayer film was formed by the above process was divided into solar cell elements by cutting. Thus, the three solar cell elements 100 shown in FIG. 1A were obtained.

Next, an ITO etching material (for example, Fe
The Cl) -containing paste was screen-printed on the surface of the solar cell element 100 in the pattern 105. Then, by washing with pure water, a part of the ITO layer was removed to ensure electrical separation between the upper electrode and the lower electrode.

Further, the ITO layer, the a-Si layer and the lower electrode layer are removed by a grinder in a part of the non-effective power generation region of each solar cell element, and the stainless substrate surface 110
By exposing, the extraction electrode from the lower electrode layer was produced. Further, a copper foil 111 having a thickness of 100 μm was connected to that place by spot welding.

On the ITO layer, a collector electrode 106 having a width of 0.3 mm was prepared by screen-printing a silver paste and baking it in an oven.

Next, in order to ensure the insulation between the bus bar electrode 107 and the lower electrode, which will be described later, a polyimide insulating tape 109 was attached to a portion adjacent to the exposed surface of the substrate.

Thereafter, the solar cell elements 100 were arranged so as not to come into contact with each other (FIG. 1).
(A)).

On the other hand, a diode ribbon (FIG. 1 (b))
Was manufactured by using two lead wire members 112 and soldering the chip diode 113 so as to sandwich it. As the chip diode, for example, a mesa type silicon chip diode (manufactured by GI) having a side of 2.5 mm and a thickness of 250 μm is preferable. The members of the two lead wires are manufactured by punching from a copper foil having a thickness of 100 μm, and one of the copper foils is provided with a T-shaped protrusion. The width of the copper foil was 5 mm, and the protrusion was 3 mm. The diode ribbon produced by the above method has a thickness of 500.
was μm. Further, the width of the copper foil at the portion soldered to the diode was set to 1.8 mm.

Next, the bus bar electrode 1 made of tin-plated copper 1
07 was placed so as to be orthogonal to the silver electrode, which is the collector electrode 106. After that, the adhesive silver ink 108 was dropped on the intersection with the silver electrode, and the silver electrode, that is, the collector electrode 106 and the bus bar electrode 107 were electrically connected.

Finally, the diode ribbon (FIG. 1B) prepared above is placed on the solar cell element (FIG. 1A) as shown in FIG. The intersection of the foil 111 and the bus bar electrode 107 was connected by soldering. In this way, the series connection and the diode connection of the solar cell elements are completed.

With the above structure, the diode ribbon can be manufactured in advance, and the lead wire portion can also serve as the connecting member. As a result, the workability of the series connection of the solar cell elements and the diode connection between the solar cell elements and the diode ribbon becomes very simple, and the number of times of soldering can be reduced.

Furthermore, EVA (ethylene vinyl acetate) was used as an adhesive layer and ETFE (copolymer of ethylene tetrafluoride and ethylene) was used as a surface protective layer for the solar cell element group that had been connected in series, and a vacuum laminator was used. The solar cell module is completed by thermocompression-bonding the resin film to form a module.

When the module was repeatedly subjected to a bending test, no change was observed in the copper foil and the diode at the connecting portion after 10,000 cycles of SERI. Also,
The characteristics of the solar cell such as efficiency and Rs did not change before and after the test. Furthermore, when a test was conducted until the copper foil became abnormal, cracks occurred in about 35,000 cycles, but it was well over the specified cycle, and it is sufficient to provide a TU-shaped protrusion. It was observed.

(Comparative Example 1) For comparison, the solar cell element group of the conventional example shown in FIG. 7 (type in which the metal foil material which is the lead portion of the bypass diode does not have a T-shaped protrusion) is also The same modularization as in Example 1 was performed, and the same repeated bending test was performed.

As a result, there was no change in the characteristics of the solar cell such as efficiency and Rs after about 10,000 cycles. However, a crack occurred in the bypass diode connected to the central solar cell element of the three series solar cell element groups.

Example 2 In this example, FIG. 2A was used in place of the diode ribbon of FIG. 1B of Example 1. The difference is that a notch is provided on the opposite side of the protrusion on the copper foil. The other points were the same as in Example 1.

First, using the same copper foil and chip diode (manufactured by GI) 204 as in Example 1, a diode ribbon as shown in FIG. 2A was produced.

The width of the copper foils 201 and 202 is basically 5 m.
m and 100 μm in thickness, which is the same as that of the first embodiment,
For the copper foil 202, a T-shaped protrusion 205 having a width of 3 mm
A cut 204 having a depth of 3 mm was provided on the opposite side of the protrusion. These copper foils can be easily made by punching, no matter how complicated the shape. The thickness of the finished diode ribbon was 500 μm.

After mounting the above-mentioned diode ribbon on the solar cell element as shown in FIG. 2 (b), the copper foil and the intersection with the bus bar electrode were connected by soldering.

Further, these were modularized in the same manner as in Example 1.

In this example, when the solar cell module manufactured as described above was repeatedly subjected to a bending test, S
It was found that, after 10,000 cycles defined by the ERI, there was no change in both the copper foil and the diode in the connection portion, and there was no deterioration in the characteristics of the solar cell, Rs, etc. after the test. Furthermore, when the test was conducted until the copper foil became abnormal, about 5
Cracking occurred after 22,000 cycles. As in Example 1, the specified cycle was cleared, but the notch was superior in durability to the case of using the copper foil having only the protrusion without the notch. Cage,
It became clear that the notch is effective for stress relaxation.

Here, an example of the shape of the copper foil 202 of FIG. 2A is shown, but there is no limitation on the shape of the cut, the depth of the cut, etc., and the positional relationship thereof is not limited. There are no restrictions.

Example 3 In this example, the diode ribbon forms used in Example 1, Comparative Example 1 and Example 2 were
A metal foil material was prepared in place of solder-plated copper having a thickness of 120 μm.

Other points were the same as in Example 1.

The solar cell module thus produced was repeatedly subjected to a bending test in the same manner as in Example 1.

When the repeated bending test was conducted for 10,000 cycles, respectively, only the sample prepared in the same manner as in Comparative Example 1 (when there was no protruding portion or notch) caused cracks in the solder-plated copper foil, and Rs was several%. Rose. Regarding the other two samples, that is, the samples produced in the same manner as in Example 1 and Example 2, the solder-plated copper foil did not change at all, and the characteristics as a solar cell did not deteriorate.

(Embodiment 4) In this embodiment, instead of connecting the copper foil to the lead-out portion from the lower electrode in Embodiment 1, no copper foil is used, and the lead-out portion 308 from the lower electrode is provided. The difference is that the protruding part of the diode ribbon was connected in the state where it was ground with a grinder.

Other points were the same as in Example 1.

FIG. 3B shows a diode ribbon used in this embodiment. The metal foil members 311 and 312 have the same width 5 mm and thickness 100 as those used in the first embodiment.
The same chip diode was used as the bypass diode 313 using a copper foil of μm.

For the copper foil 312, 1 cm at the right end of the foil
It has a long T-shaped protrusion 315 and a notch having a depth of 3 mm on the opposite side.

After mounting the prepared diode ribbon as shown in FIG. 3 (c), the protruding portion 315 of the metal foil material and the solar cell element 308 were connected by spot welding. Also,
The 315 portion of the diode ribbon and the 311 portion of the adjacent diode ribbon were soldered.

In this example, since the projecting portion is connected to the lead-out portion of the lower electrode as described above, the number of parts can be reduced, the working process can be shortened, and the cost can be reduced.

Furthermore, these solar cell element groups were used in Example 1.
When a module was made by the same method as above and repeated bending tests were performed, no abnormality was found after 10,000 cycles. Moreover, no abnormality appeared even after 100,000 cycles.

Therefore, by connecting a part of the metal foil material, which is the lead part of the diode, to a part of the solar cell element group, the bending stress can be received by the entire element, so that the stress applied to the diode part Has been reduced, and has further improved properties in terms of durability.

Example 5 This example is different from the diode ribbon form used in Example 1 in that copper foils having different annealing times were used.

Other points were the same as in Example 1.

Five types of copper foils having different hardness shown in Table 2 were prepared by changing the annealing time of the copper foil. Hv is Vickers hardness

[0109]

[Table 2] A solar cell module was manufactured in the same manner as in Example 1 except for the above five copper foils, and repeated bending tests were performed.

The results are shown in Table 1 and FIG. Figure 4
In the graph, the horizontal axis represents the Vickers hardness of copper, and the vertical axis represents the number of repeated bendings until an abnormality such as cracking occurs.

Due to the effect of providing the T-shaped protrusions, all samples exceeded the SERI standard of 10,000 times.

In this example, when the Vickers hardness of the copper foil is 70 or more, cracking occurs in 50,000 cycles or less, whereas when the Vickers hardness is 70 or less, the durability is rapidly improved and the Vickers hardness of 50 is obtained. In the sample of
The result was that cracking did not occur even after 100,000 times.

From the above, it is possible to extend the durability against repeated bending by using a soft material having a Vickers hardness of 70 or less for the metal foil material.

(Example 6) The present example is different in that a hard copper foil, which will be described later, is further provided in a region where the ITO layer produced in Example 1 is etched.

Other points were the same as in Example 1.

The sixth embodiment of the present invention will be described below with reference to FIG.

Two solar cell elements 500 were manufactured in exactly the same manner as in Example 1.

First, an ITO etching material (FeC
The l ₃ ) -containing paste was screen-printed in a pattern 501 and then washed with pure water to etch a part of the ITO layer to ensure electrical separation between the upper electrode and the lower electrode. Next, a polyimide insulating tape was attached to the outer side of the etching region (not shown), and a hard copper foil 502 having a thickness of 100 μm was attached to the tape with a double-sided tape (FIG. 5A). At this stage, the copper foil 502 is
It is electrically floating.

Further, a hard copper foil 503 having a thickness of 100 μm was connected by ultrasonic welding to a position just outside and parallel to the hard copper foil 502 as shown in FIG. 5 (a), and was taken out from the lower electrode. .

The right ends of the two copper foils 503 are shown in FIG.
As shown in (a), it was covered with a polyimide insulating tape 504.

Here, a silver-coated wire was prepared in which a copper wire having a diameter of 100 μm was coated with a silver paste to a thickness of 20 μm and dried. The wire was arranged as shown in FIG. 5 (a), and pressed at 150 ° C. for 20 seconds while applying a pressure of 1 atm to bond the wire to the effective area of the solar cell element to form a collecting electrode 505.

Further, the hard copper foil 502 and the collector electrode 505
In order to electrically connect and, the silver paste was doted on the collector electrode 505 on the copper foil 506, and was open and cured. As a result, the copper foil 502 can serve as an extraction electrode from the upper electrode.

Next, a planar type silicon chip diode 510 having a side of 3.5 mm and a thickness of 250 μm was prepared. Further, lead wire members 511 and 512 are prepared by punching from a copper foil having a thickness of 100 μm.
12 was provided with a T-shaped protrusion 513 and a notch 514 with an R at the tip. The width of the copper foil is 5 mm, the T-shaped protrusion 513 is 3 mm, and the cut portion 514 is 3 mm deep.
mm. By using these copper lead members, the chip diode 510 is soldered so as to be sandwiched,
A diode ribbon as shown in (b) was prepared. The thickness of the finished diode ribbon was 500 μm.

Here, the prepared diode ribbon is shown in FIG.
After mounting on the polyimide insulating tape 504 as shown in (b), the X, Y, and Z parts were soldered. As a result, the X-Y connection is connected to the bypass diode of each solar cell element, and the Y-Z connection is connected in series with the adjacent element. Further, in this configuration, two bypass diodes are installed for one solar cell element.

In the present example, as described above, even in the case of the electrode configuration shown in FIG. 5A, the diode ribbon as shown in FIG. 5B simplifies the connection and shortens the working process. Therefore, the cost can be reduced.

Further, when a module was repeatedly subjected to a bending test as in Example 1, there was no problem even after 100,000 cycles.

[0127]

As described above, according to the first aspect of the present invention, it is possible to obtain a photovoltaic element which is resistant to bending stress, can be easily manufactured, and is low in cost. Therefore, according to the present invention, it is possible to improve the durability when used outdoors and to provide a highly reliable solar cell module.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating an embodiment example and a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a second embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating a fourth embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating Example 5 of the present invention, and is a graph showing the relationship between the Vickers hardness of copper and the number of times of repeated bending.

FIG. 5 is a schematic diagram illustrating a sixth embodiment of the present invention.

FIG. 6 is a schematic view of a connection form of a conventional solar cell module.

FIG. 7 is a schematic diagram illustrating another connection form of a conventional solar cell module.

[Explanation of symbols]

100, 300, 500, 600, 700 Solar cell element, 101, 601 Substrate, 102, 602 Lower electrode layer, 103, 603 Semiconductor layer, 104, 604 Upper electrode layer, 105, 306, 605, 706 One of upper electrode layer Part, 106, 301, 606, 701 Current collecting electrode, 107, 302, 607, 702 Bus bar electrode, 108, 307, 608, 707 Conductive adhesive, 109, 309, 504, 709 Insulating tape, 110, 308, 708 Exposed part of substrate, 111, 611, 703 metal body, 112, 201, 202, 311, 312, 711 metal foil body, 113, 203, 313, 510, 630, 710 bypass diode, 204, 315, 513 T-shape Projection, 205, 314, 514 notch.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuo Fujisaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (9)

[Claims] 1. A photovoltaic element in which at least one bypass diode is installed for each photovoltaic element,
The bypass diode is a flat diode, the lead wire of the bypass diode is made of two metal foil materials, and the bypass diode and the metal foil material are connected via a connecting material. Electromotive element 2. The photovoltaic element according to claim 1, wherein the metal foil material contains at least one component of gold, silver, copper, lead or tin. 3. The metal foil material has a thickness of 50 μm to 200 μm.
The photovoltaic element according to claim 1 or 2, wherein m is m. 4. The photovoltaic element according to claim 1, wherein the metal foil material has a Vickers hardness of 70 or less. 5. The photovoltaic element according to any one of claims 1 to 4, wherein the connecting material is one in which fine metal particles are dispersed in solder. 6. The metal foil material and the bypass diode,
The photovoltaic element according to any one of claims 1 to 5, wherein a contact area of a portion to which the connecting material connects is 50% or more and 90% or less of the flat diode area. 7. At least one of the metal foil members has a protrusion, and a plurality of photovoltaic elements are connected using the protrusion. 6. The photovoltaic element according to any one of 6 8. At least one of the metal foil materials has both a notch and a protrusion, and a plurality of photovoltaic elements are connected using the protrusion. The photovoltaic element according to any one of claims 1 to 6. 9. The photovoltaic element according to claim 7, wherein the protrusions of the all-genuine foil material are used for connection.