JPH04116986A - Integrated solar cell and manufacture of the same - Google Patents

Abstract

PURPOSE:To prevent an accident such as breakage of a lead wire, and improve reliability at lower cost by integrating solar cells in series on an integrated substrate. CONSTITUTION:A plurality of solar cells on a substrate in which an insulating layer 102 is formed are connected in series to make an integrated solar cell. Lower electrodes 103, semiconductor layers 104, and upper electrodes 105 are formed. The edges or whole surfaces of the solar cells except part 109 of the lower electrodes and part 110 of the upper electrodes are coated with an insulating material 106. The part 109, which is not coated, of the lower electrode of one of adjacent solar cells and the upper electrode 110 are connected with a conductive material 107 across the insulating material 106. Because the solar cells are connected in series on the integrated substrate, reliable solar cells free from breakage of a lead wire are made at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solar cell and a method for connecting the same. In particular, the present invention relates to integrated thin film solar cells connected in series on a single substrate and a method for manufacturing the same.

[Prior art and problems to be solved by the invention] Regardless of the type of solar cell, the output voltage is generally low;
When used as a power source for general equipment, it must be connected in series to increase the voltage.

At this time, in solar cells using crystalline silicon or polycrystalline silicon as a semiconductor layer, semiconductor wafers on which solar cells are formed are connected in series by lead wires.

However, when connecting the devices in series using lead wires, there is a risk of wire breakage, and there are also problems in that the assembly process is complicated and the manufacturing cost is high.

On the other hand, in solar cells using amorphous silicon as a semiconductor layer, a method is used in which they are connected in series on an integrated substrate without using lead wires. As an example of this method, as shown in Japanese Patent Publication No. 58-21827, a solar cell divided into several parts is formed on an integrated substrate, and as shown in the plan view of FIG. There is a method of connecting the upper electrode 1604 and lower electrode 1602 of matched solar cells at a location where the semiconductor layer 1603 is not formed.

According to this method, a practical output voltage can be obtained from a single substrate, the assembly process of the solar cell module is simplified, manufacturing costs are reduced, and there is no fear of wire breakage (and the manufacturing yield is improved). has also improved.

However, when the area of the solar cell is increased, the resistance value of the transparent electrode (upper electrode) becomes thicker, which causes a problem that the photoelectric conversion efficiency of the solar cell decreases.

Further, Japanese Patent Publication No. 62-5353 discloses a method of connecting solar cells divided on an integrated substrate at adjacent boundary portions, as shown in the cross-sectional view of FIG. According to this method, by optimizing the width of the solar cell between the connection parts, the resistance value of the transparent electrode (upper electrode) is lowered, and even in large-area solar cells, there is little decrease in photoelectric conversion efficiency ( became.

However, in this method, the lower electrode 1702, the amorphous silicon layer 1703, and the upper electrode 1704 must be patterned separately.
Patterning is required before the deposition of No. 4, which lengthens the process in which the semiconductor layer is exposed to the atmosphere, which may adversely affect the characteristics of the solar cell.

Further, the lower electrodes 1702 of adjacent solar cells are insulated by an amorphous silicon layer 17o3, but the amorphous silicon layer 1703 is a semiconductor layer, and
Since it includes a low-resistance semiconductor layer such as a type amorphous silicon layer or an n-type amorphous silicon layer, there are problems in that leakage current occurs and dielectric strength voltage decreases.

Furthermore, when a transparent electrode is used for the upper electrode 1704, there is a problem in that when the thickness of the transparent electrode is made thin in order to ensure light transmittance, disconnection occurs due to a step at the connecting portion.

[Objective of the Invention] The object of the present invention is to solve the problems of the conventional technology described above, and to provide a large-area, serialized, highly reliable, simple manufacturing process, low-cost, and The purpose is to provide integrated solar cells.

[Means for Solving the Problems] The present inventor has completed extensive research to achieve the above-mentioned object, and the integrated solar cell of the present invention and its manufacturing method are an integrated solar cell in which a plurality of solar cells each having a semiconductor layer and an upper electrode are connected and integrated; A conductive material layer connecting one of the upper electrodes and the other lower electrode of the solar cell,
It is characterized by being formed across the insulating material between individual solar cells.

[Function] In the present invention, when directly connecting divided solar cells on an integrated substrate, the lower electrodes of adjacent solar cells are not insulated with a semiconductor layer as in the conventional example, but with an insulating material. By insulating, leakage current can be eliminated and dielectric strength can be improved.

Further, by creating a structure in which the semiconductor layer and the upper electrode can be patterned simultaneously, the step of patterning only the semiconductor layer can be omitted, and the surface of the semiconductor layer can be prevented from being exposed to the atmosphere for a long time.

In addition, by providing a conductive material that connects the upper and lower electrodes of adjacent solar cells independently of the upper electrode, it is possible to eliminate disconnections due to differences in connection level even when the upper electrode is thin. .

Based on the above-mentioned knowledge, the present inventor achieved the above-mentioned object with an integrated solar cell having the following configuration.

[Example J Hereinafter, preferred embodiments of the present invention will be described in explanatory diagrams Figures 1 to 3.
This will be explained based on the diagram.

FIG. 3 is an overview diagram of an example of an integrated solar cell of the present invention, in which 301 is a plurality of solar cells formed on an integrated substrate;
Reference numeral 02 indicates a connection portion for connecting a plurality of solar cells 301 in series, and reference numerals 303 and 304 indicate extraction electrodes.

FIG. 1 is an example of an enlarged cross-sectional view of a connecting portion A in FIG. 3 in order to explain the present invention in detail.

Further, FIG. 2 is a diagram showing another example of a cross section of the connecting portion A in FIG. 3.

As shown in FIGS. 1 to 3, this is an integrated solar cell in which a plurality of solar cells 301 formed on an insulating substrate 201 or a substrate in which an insulating layer 102 is formed on a conductive substrate 101 are connected in series. It has lower electrodes 103 and 202, semiconductor layers 104 and 203, and upper electrodes 105 and 204. Then, the ends or the entire surface of the solar cell 301 are covered with parts 109 and 209 of the lower electrode and part 110 of the upper electrode.
, 210 are covered with an insulating material 106, 205. A portion 109, 209 of one lower electrode not covered with an insulating material and an upper electrode 110, 210 of the other adjacent solar cell are connected across the insulating material 106, 205 by a conductive material 107.2-06. ing.

With the configuration of the present invention, by connecting solar cells in series on an integrated substrate, it is possible to create highly reliable solar cells at a lower cost and without breakage of lead wires than when connecting in series using lead wires. can be provided.

In addition, because the ends or all of the adjacent solar cells on the integrated substrate are coated with an insulating material except for part of the lower electrode and upper electrode, leakage current between solar cells connected in series is prevented. (As a result, the dielectric strength can be greatly improved.

Furthermore, since the semiconductor layer and the upper electrode can be patterned at the same time, the manufacturing process is simplified and the semiconductor layer does not need to be exposed to the atmosphere for a long time after it is formed.

Furthermore, even when a transparent electrode is used as the upper electrode, the material for connecting the lower electrodes of adjacent solar cells is not the upper electrode itself (but a conductive material is used, so disconnections due to differences in the connection part can be eliminated). .

Moreover, by optimizing the width d of the solar cell between the connecting parts shown in FIG. 3, it is possible to increase the area without lowering the photoelectric conversion efficiency.

The configuration of each part of the integrated solar cell of the present invention will be explained in detail below.

In the present invention, the substrate used is an insulating substrate or a conductive substrate on which an insulating layer is formed. As the insulating substrate, a glass substrate or a polymer film such as polyimide or polyethylene terephthalate can be used.

Further, as the conductive substrate, a metal substrate such as stainless steel can be used.

In addition, as an insulating layer formed on a conductive substrate, SiO
□, 5isN4. A thin film of an inorganic material such as AltOs may be used, or a synthetic resin may be applied.

In the present invention, the upper electrode and the lower electrode are Aβ.

Ag, Cr, Ni, Au, Pb, Sn, Z
Metals such as n, Mg, Cu, Fe, and W, or transparent conductive films such as ITO, Snow, and ZnO are preferably used.

In the present invention, as the semiconductor layer, amorphous silicon, polycrystalline silicon, Cds, CdTe, CuIn
A semiconductor thin film such as 5ea is preferably used.

In the present invention, the insulating material that covers the electrodes and the ends of the semiconductor layer of the solar cell may be configured to cover only the ends as shown in FIG. 1, or may be applied to the entire surface as shown in FIG. It may be possible to have a structure in which only the connecting portion between the lower electrode and the upper electrode is removed.

Insulating materials include SiO2, 5iJ4. The material is selected from inorganic materials such as Al□01, and synthetic resins such as polyethylene epoxy resin, polyamide resin, polyimide, polyester resin, polycarbonate resin, and fluororesin.

Furthermore, in a solar cell in which light enters from the upper electrode side, when the entire surface of the solar cell is coated with the insulating material, a material with a small visible light absorption coefficient is selected from among the insulating materials and used.

If the thickness of the layer of insulating material is too thin, the dielectric strength will decrease,
If it is too thick, there is a risk of disconnection of the conductive material connecting the upper and lower electrodes of adjacent solar cells. Therefore, the preferred thickness of the insulating material layer varies depending on the material used, but is preferably 0.2 μm to 3 mm.
, more preferably 1 μtrr to 1 am, optimally 5 μI! The thickness is preferably 1 to 500 μm.

The conductive materials that connect the upper and lower electrodes of adjacent solar cells include Aj2, Ag, Cr, and Ni.
, Au.

Pb, Sn, Zn, Mg, Cu, Fe, W
It is possible to use conductive resins using metals such as, alloys such as solder, or powdered metals such as Ag paste, or a combination of two or more of the above substances as shown in FIG.

Further, by combining metal and conductive resin to form a two-layer structure as the conductive substance, contact with the electrode can be ensured, and the resistance value of the conductive substance as a whole can be lowered.

Further, in the integrated solar cell of the present invention, a surface protection material and a filling material are appropriately used depending on the configuration of the solar cell.

Examples of surface protection materials and filler materials that can be used include glass, acrylic resin, polyethylene terephthalate, silicone resin, polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), and the like.

Furthermore, the integrated solar cell of the present invention may have a configuration in which a current collecting electrode made of metal or conductive resin is provided above or below the transparent electrode.

Next, a method for manufacturing an integrated solar cell according to the present invention will be described.

In the integrated solar cell of the present invention, a lower electrode, a semiconductor layer, and an upper electrode are formed on an insulating substrate or a conductive substrate with an insulating layer formed thereon, and the lower electrode is patterned and divided into a plurality of parts. The semiconductor layer and the upper electrode are patterned so that a part of the solar cell is exposed, and an insulating layer is formed to cover the ends or the entire surface of the patterned solar cell.
It is manufactured by removing part of the lower electrode of one adjacent solar cell and part of the upper electrode of the other insulating layer, connecting the removed parts with a conductive material, and forming a protective film over the entire surface. Ru.

Here, as a method for patterning each layer, a method such as mask vapor deposition, mask deposition, photolithography, or laser scribing can be used.

In addition, manufacturing can be performed by patterning the lower electrode and patterning the semiconductor layer and the upper electrode, whichever is performed first.

Furthermore, when two types of conductive substances are used in combination as in the example shown in FIG. 2, the second conductive layer 207 is formed successively after the first conductive layer 206 is formed. At this time, for example, by using Ag paste as a conductive resin as the first conductive layer, good contact with the electrode can be achieved, and by using metal as the second conductive layer, the entire conductive layer can be resistance can be lowered.

Hereinafter, the integrated solar cell of the present invention and its manufacturing method will be explained in detail with reference to Examples.

(Example 1) The integrated solar cell having the configuration shown in FIG.
It was manufactured using the steps shown in the figure.

The conductive substrate 101 has a thickness of 0.15 mm and a width of 30 cm.
Using a strip-shaped substrate with a length of 300 m and a length of 300 m, each layer was continuously formed by a roll to roll method using a continuous film forming apparatus.

First, as shown in FIG.
SiO* was deposited to a thickness of 3 .mu.m as an insulating layer 102 by a method, and on top of this, 5,000 layers of A2 and 500 layers of Cr were deposited as a lower electrode 103, and 5,000 layers of ZnO were deposited by a sputtering method.

Next, n-type amorphous silicon, intrinsic amorphous silicon germane, p-type mechanically crystalline silicon, n-type amorphous silicon, intrinsic amorphous silicon, and p-type mechanically crystalline silicon were deposited in this order by a plasma CVD method, and a tandem structure was formed. forming a semiconductor layer 104;
ITO was deposited by 700 people to form the upper electrode 105.
A solar cell having the configuration shown in FIG. 5 was formed.

Next, as shown in FIG. 6, the upper electrode 10 at the portion 601
5, the semiconductor layer 104, and the lower electrode 103 at a wavelength of 1.06μ.
YAG laser with Q-switch pulse of m, output o, g
w, a laser beam with a diameter of 50 μm was irradiated with a frequency of 4KH2, and the particles were removed by scanning at a speed of 100 mm/sec.

Next, as shown in FIG. 7, the semiconductor layer 10 in a portion 701 is
4 and the upper electrode 105 using a Q-switched pulsed YAG laser with a second harmonic wave with a wavelength of 0.53 μm and an output of 0.
．． A laser beam with a diameter of 100 μm was irradiated at 3 W and a frequency of 4 KHz and removed by scanning at a speed of 100 mm/see, resulting in a structure in which a part of the lower electrode 103 was exposed.

Next, as the insulating material 106, epoxy resin is applied by screen printing to a thickness of about 30 μm and a width of about 150 μm.
The grooves formed in the steps shown in FIGS. 6 and 7 were filled to form the structure shown in FIG. 8.

Next, a YAG laser with a Q-switched pulse with a wavelength of 1.06 μm was used, the output was 0.3 W, the frequency was 4 KH, and the diameter was 50 μm.
100II100II
1, the epoxy resin at a portion 901 was removed to expose 7 portions of the lower electrode 103, as shown in FIG. At this time, colored epoxy resin was used to absorb laser light.

Next, a part of the exposed lower electrode 103 and a part of the upper electrode 105 of the adjacent solar cell were connected with a conductive material 107. As the conductive substance 107, Ag paste is used, and the thickness is about 30 μm and the width is about 150 μm by screen printing.
was applied as shown in FIG.

Next, we applied EVA and polyvinyl fluoride (P) to the front and back sides.
A protective film 108 was formed using VF) to form an integrated solar cell having the connection portion configuration shown in FIG.

By cutting the strip-shaped SUS substrate produced in this way into a desired size, it was possible to form a solar cell with a desired output voltage and output current.

For example, if you create an integrated solar cell with 25 stages integrated in series on a 30 cm x 30 cm substrate, the AMl, 5.100 a
When the current and voltage characteristics were measured with a solar simulator of ``+w/cm'', the maximum output was 10 when the output voltage was 30V.
J (Comparative Example 1) A solar cell having the same lower electrode 103, semiconductor layer 104, and upper electrode 105 as in Example 1 was manufactured using
When the structure as shown in FIG. 17 was connected in series using the method disclosed in
Because it was thin and thin, wires broke at the step and could not be integrated.

(Example 2) An integrated solar cell was manufactured using the same manufacturing process as Example 1 with the following differences.

The insulating layer 102 was deposited to a thickness of 5 isN and 3.5 μm by the LPCVD method. Furthermore, Ag and C electrodes are laminated as the lower electrode 103, and p-type CdTe is used as the semiconductor layer 104.
and n-type CdS were laminated, the n-type CdS also served as the upper electrode 105, and an AgO current collecting electrode was formed on the upper electrode 105. Furthermore, silicone resin was screen printed as the insulating material 106.

Further, as the conductive substance 107, Aρ was deposited to a thickness of 1 μm by mask vapor deposition. In this way, 30cm x 20
When we manufactured integrated solar cells connected in series in 25 stages with a size of crrr, AMl, 5.100 a+W/
A maximum output of 3.5 W was obtained with "ca+".

(Example 3) The integrated solar cell of the present invention shown in FIG. 2 was manufactured by the following steps.

11 to 15 are explanatory diagrams of the manufacturing process of the integrated solar cell of the present invention shown in FIG. 2.

First, a glass substrate was used as the insulating substrate 201, 2000 5nu2 transparent electrodes were formed as the lower electrode 202 by sputtering, and patterned by photolithography as shown in FIG. 11.

Next, as the semiconductor layer 203, a p-type amorphous SiC layer, an intrinsic amorphous silicon layer, and an n-type amorphous silicon layer were sequentially deposited using a plasma CVD method using a total of 5000 people, and as an upper electrode 204, 500 Cr and 1500 Cr were deposited in sequence.
The structure shown in Fig. 12 was obtained by vapor deposition.

Next, the semiconductor layer 203 and the upper electrode 204 were patterned by photolithography centering around the patterned portion of the transparent electrode, so that a structure was obtained in which a part of the lower electrode 202 was exposed as shown in FIG.

Next, as an insulating material 205, amorphous SiN is deposited to a thickness of 1 μm over the entire surface by plasma CVD, and by photolithography, as shown in No. 141i1, a part of the lower electrode of one of the adjacent solar cells and a part of the upper electrode of the other one are deposited. The amorphous SiN on top was removed.

Next, Ag paste was applied as a conductive substance 206 by screen printing, and cream solder was applied as a conductive substance 207 by screen printing, so that adjacent solar cells were connected in series as shown in FIG.

Next, EVA and PVF were formed as the protective film 208, and an integrated solar cell as shown in FIG. 3, which featured the connection portion shown in FIG. 2, was manufactured.

Using this, 30. With a size of cm x 40 cm,
When we measured the integrated solar cells connected in 20 stages in series, we found that the AMl was 5.100 m17 cm'' and the maximum output was 6 W.

(Example 4) An integrated solar cell was manufactured using an insulating substrate as a substrate with the configuration of the connection part shown in FIG.

Polyethylene terephthalate (PET) is used as an insulating substrate.
), 4000 layers of Ag and 1000 layers of Cr were deposited as the lower electrode 103, and the lower electrode was patterned by photolithography as shown in FIG.

Next, as the semiconductor layer 104, n
A total of 6,000 layers of type amorphous silicon layer, intrinsic amorphous silicon layer, p-type mechanical crystal silicon, n-type amorphous silicon layer, intrinsic amorphous silicon layer, and p-type mechanical crystal wrinkles were deposited, and 700 layers of ITO, which is a transparent electrode, was deposited as the upper electrode. After manual evaporation, Ag paste was applied as a current collecting electrode onto the transparent electrode by screen printing, resulting in a structure using a current collecting electrode as shown in FIG.

Next, an etching paste containing HCI and FeCl5 was screen printed to remove ITO around the separated part of the lower electrode.
Using the patterned ITO as a mask, the amorphous silicon layer serving as the semiconductor layer was etched to expose a portion of the lower electrode as shown in FIG.

Next, a polyimide photoresist was applied as an insulating material 106 to the groove portion shown in FIG. 13 using a dispenser, resulting in the structure shown in FIG. 8.

Next, a light-shielding material was partially applied onto the resist using a dispenser, and ultraviolet rays were irradiated to ash the resist so as to expose a portion of the lower electrode as shown in FIG.

Next, Ag paste is applied as a conductive substance 107 using a dispenser as shown in FIG.
As No. 8, an integrated solar cell having the connection portion configuration shown in FIG. 1 was manufactured by coating with EVA and PVF.

Using this, we manufactured integrated solar cells with a size of 30 cm x 40 cm and connected in series in 10 stages.
, 5.100 mW/am' with a maximum output of 9w.

[Effects of the Invention] As explained above, by integrating solar cells in series on a single substrate using the integrated solar cell of the present invention, accidents such as breakage of lead wires for serialization can be prevented ( As a result, we were able to provide a low-cost, highly reliable integrated solar cell.

In addition, the ends or all of the solar cells connected in series on the integrated substrate are covered with an insulating material, except for the part where the lower electrode of one of the adjacent solar cells and the upper electrode of the other are connected. This eliminates leakage current between solar cells connected in series, improving characteristics and greatly increasing dielectric strength.

In addition, by having a structure that allows patterning of the semiconductor layer and the upper electrode at the same time, there is no negative effect on the device due to the semiconductor layer being exposed to the atmosphere for a long time after the semiconductor layer is formed, and the process is also simplified. We were able to reduce costs.

In addition, as a material for connecting adjacent solar cells in series,
By using a conductive material independent of the upper electrode,
Even when the upper electrode is thin, there is no longer a disconnection due to a step difference.

In addition, by using a synthetic resin as an insulating material and a conductive resin such as Ag paste as a conductive material, the manufacturing process is simplified, and it is possible to provide a low-cost and highly reliable integrated solar cell. was completed.

In addition, by combining metal and conductive resin as conductive substances to form a two-layer structure, it is possible to improve contact with the electrodes, and the resistance of the conductive layer as a whole can be lowered. is obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a connecting portion of an integrated solar cell according to the present invention. FIG. 2 is a sectional view showing another example of the connection portion of the integrated solar cell of the present invention. FIG. 3 is a schematic diagram of an example of the connection part of the integrated solar cell of the present invention. 4 to 10 are cross-sectional views of the manufacturing process of the integrated solar cell shown in FIG. 1. 11 to 15 are cross-sectional views of the manufacturing process of the integrated solar cell of FIG. 2. FIG. 16 is a plan view of an example of a conventional integrated solar cell. FIG. 17 is a sectional view of another example of a conventional integrated solar cell. 101... Conductive substrate, 102... Insulating layer, 103
... lower electrode, 104 ... semiconductor layer, 105 ...
Upper electrode, 106... Insulating material, 107... Conductive material, 108... Protective film, 109... Lower electrode connecting portion, 110... Upper electrode connecting portion, 201...
- Insulating substrate, 202... lower electrode, 203... semiconductor layer, 204... upper electrode, 205... insulating material,
206... First electrically conductive material, 207... Second electrically conductive material, 208... Protective film, 209... Lower electrode connection portion, 210... Upper electrode connection portion, 301
... (divided) solar cell, 302 ... connection part, 303, 304 ... extraction electrode, 601 ... part from which lower electrode, semiconductor layer and upper electrode are removed, 701.
... Part where the semiconductor layer and upper electrode are removed, 901...
Portion from which insulating material is removed, 1601...Insulating substrate, 1
602... Lower electrode, 1603... Amorphous silicon layer, 1604... Upper electrode, 1605... Leading electrode, 1701... Insulating substrate, 1702...
Lower electrode, 1703...Amorphous silicon layer, 1
704... Upper electrode, 1705... Insulating film. Agent Patent Attorney Sanno Yearly Kudzu py 1/j Figure 16 Figure 4 4 θl

Claims (8)

[Claims] (1) In an integrated solar cell in which a plurality of solar cells having a lower electrode, a semiconductor layer, and an upper electrode are connected and integrated, an insulating material insulating the ends or the entire surface of the plurality of solar cells. and a conductive material layer connecting the upper electrode of one of the adjacent solar cells and the lower electrode of the other adjacent solar cell,
An integrated solar cell characterized by being formed across an insulating material between individual solar cells. (2) The integrated solar cell according to claim 1, wherein a protective layer is formed on the entire surface of the solar cell so as to cover the insulating material and the conductive material. (3) The integrated solar cell according to claim 1, wherein the insulating material is a synthetic resin. (4) The integrated solar cell according to claim 1, wherein the insulating material is an inorganic material. (5) The integrated solar cell according to claim 1, wherein the conductive substance is a metal or a conductive resin. (6) The integrated solar cell according to claim 1, wherein the conductive material has a two-layer structure combining metal and conductive resin. (7) The integrated solar cell according to claim 1, wherein the semiconductor layer is made of amorphous silicon or an amorphous silicon alloy. (8) A method for manufacturing an integrated solar cell in which a plurality of solar cells each having a lower electrode, a semiconductor layer, and an upper electrode are connected and integrated, wherein the lower electrode is partially exposed. The semiconductor layer and the upper electrode are patterned to form an insulating layer so as to cover the ends or the entire surface of the solar cell, and a part of the lower electrode of one of the adjacent solar cells and a part of the upper electrode of the other solar cell are formed. A method of manufacturing an integrated solar cell, comprising: removing the insulating layer from a portion thereof, and forming a conductive layer so as to connect the removed portion across the insulating layer.