JP2002280591A - Solar cell module - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a solar cell module which can be broken by solar cell elements due to thermal stress applied at the time of soldering and long-term temperature cycle stress. SOLUTION: A plurality of solar cell elements 1a, 1b having back electrodes 2a, 2b on the back and front electrodes 3a, 3b and current collecting electrodes 4a, 4b on the front are arranged in parallel, and one solar cell element 1a is provided. And a back electrode 2b of another solar cell element 1b adjacent to the current collecting electrode 4a of one solar cell element 1a.
Is a solar cell module having a strip-shaped connection tab 10 for connecting the solder tabs. The connection tab 10 has a solderable area 10c where soldering is possible and a non-soldering area 10b where solder is not attached in the longitudinal direction. A plurality of them are provided alternately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solar cell module in which a plurality of solar cell elements are connected in series and in parallel, and more particularly to a solar cell module having a high temperature cycle performance.

[0002]

2. Description of the Related Art Among various types of solar cells, amorphous silicon solar cells and polycrystalline silicon solar cells have been studied intensively because they can be manufactured in a large area and the manufacturing cost is low. Since these solar cells require a voltage of several tens of volts or more in practical use, adjacent solar cells are used in series for a plurality of solar cell elements.

[0003] For example, FIG.
It is a top view which shows the connection state of the general conventional solar cell module disclosed by Unexamined-Japanese-Patent Publication. FIG. 5 is a side view of the solar cell module. 4 and 5, 1
Reference numerals a and 1b denote a plurality of flat-plate solar cell elements arranged side by side;
a and 2b are back electrodes provided on the entire back surface of the solar cell elements 1a and 1b, 3a and 3b are front electrodes provided on the surface of the solar cell elements 1a and 1b at predetermined intervals,
Reference numerals 4a and 4b denote front electrode current collecting electrodes for connecting the respective 3a and 3b, and 5 denotes a connection tab for connecting the current collecting electrode 4a of one solar cell element 1a and the back electrode 3b of another adjacent solar cell element 1b. is there.

FIG. 6 is a view similar to that of JP-A-11-3128.
FIG. 2 is a sectional structural view of a general conventional solar cell module disclosed in Japanese Patent Publication No. 20; In FIG. 6, 6 is a solar cell module resin, 7 is a front member, and 8 is a back member.

As the solar cell element 1a, a P-type silicon substrate having a thickness of about 300 μm is used. An N-type layer is formed on this substrate, and thereafter, the conversion efficiency is improved.
A surface treatment such as an anti-reflection film is applied.

[0006] In this solar cell element 1a, more sunlight is applied to the surface-treated surface of the solar cell element 1a.
A plurality of conductive pastes having a width of about 100 μm are applied linearly to the surface of the solar cell element 1a at intervals of about 2 mm on the surface of the solar cell element 1a in order to take out the converted electric energy without waste. 3a and 3b are formed.

Further, in order to collect electric energy from the surface electrodes 3a and 3b, a conductive paste is applied linearly with a width of about 2 mm in a direction perpendicular to the surface electrodes 3a and 3b, and then baked to collect. Electrodes 4a and 4b are formed.

Also, a conductive paste is applied to the back surfaces of the solar cell elements 1a and 1b and baked to form back electrodes 2a and 2b.
b is formed.

Front electrode 3a, current collecting electrode 4a, back electrode 2
The solar cell element 1a in which a is formed is connected to the adjacent solar cell element 1b by a tab wire 5 to obtain a predetermined voltage.

The tab wire 5 has a thickness of 100 μm such as copper foil.
A thin metal plate having solder attached thereto is used. The width is slightly smaller than the current collecting electrode 4a.

One end of the tab wire 5 is superimposed on the current collecting electrode 4a of the solar cell element 1a, and the melting temperature of the solder is 200.
Heating by hot air or lamp heating to ℃ or more and soldering.

Similarly, on the back electrode 2b of the adjacent solar cell element 1b, the other end of the tab wire 5 is superposed and soldered on the back electrode 2b, and a plurality of solar cell elements are connected in series. Of the manufactured solar cell module.

Thereafter, the solar cell module thus manufactured is generally laminated with a back member 8, a highly transparent resin 6, and a surface member 7 such as glass, and then heated and compressed to form a solar cell module. Will be sealed.

In the solar cell module constructed as shown in FIGS. 4 to 6, the solar cell elements 1a and 1b are
There is a problem that the solar cell elements 1a and 1b are easily damaged when the connection is made. That is, since the tab wire 5 is made of a metal such as a copper foil, its thermal expansion coefficient is
It is larger than the silicon substrate on which a and 1b are based. Therefore, in the conventional method in which the tab wire 5 is connected by heating to the solder melting temperature, when the temperature returns to the normal temperature, the difference in the coefficient of thermal expansion between the tab wire and the solar cell elements 1a, 1b causes the solar cell elements 1a, 1b to change. 1b is stressed. For this reason, there was a tendency that the thinner the silicon substrate, the more likely it was to be damaged.

Further, since the tab wire 5 also has some thickness, a pressing force is locally applied to the tab wire 5 by heating and compression when sealing with the resin 6, but this is also a problem with the sun. This causes the battery elements 1a and 1b to be damaged.

Further, since the solar cell module is usually installed outdoors and used for a long period of time, it is always subjected to a large amount of environmental stress. In particular, the temperature is higher than the ambient temperature during power generation during the day, while it is exposed to temperature stress every day, such as when it is not generating power at night, it becomes the same minimum temperature as the surroundings. Cycle performance is required.

However, in the solar cell module constructed as described above, the tab wire 5 and the solar cell elements 1a, 1
Since a stress is applied due to a difference in the coefficient of thermal expansion from b, similar damage occurs to the solar cell elements 1a and 1b, and the damage is enlarged by aging.

As a method for solving such a problem, for example, a solar cell module shown in FIGS. 7 to 11 shown in Japanese Patent Application Laid-Open No. H11-31820 has been proposed. FIG. 7 is a top view showing a connection state of a conventional solar cell element. FIG. 8 is a side view of the solar cell module. FIG. 9 is a sectional structural view of the solar cell module. Further, FIG. 10 is an exploded sectional view when the solar cell element is sealed with a resin, and FIG. 11 is a sectional view taken along the line AA ′ in FIG. In the figure, 6a is a resin sheet, 9 is a connection member, 9a is a connection part, 9b is a connection part, and the same parts as those shown in FIGS. 4 to 6 are denoted by the same reference numerals.

A connecting member 9 for connecting adjacent solar cell elements 1a and 1b in this solar cell module.
Is not plate-like like the tab wire 5 shown in FIGS. 4 to 6 but is separated from each other, and the connection surface between the solar cell elements 1a and 1b is formed on the current collecting electrode 4a and the back surface electrode 2b. It has a structure having a plurality of connecting portions 9a intermittently having a flat surface to be formed.

The plurality of connection portions 9a are raised from the connection surfaces with the solar cell elements 1a and 1b, thereby forming connection portions 9b separated from the connection surfaces with the solar cell elements 1a and 1b.
Are connected to each other.

Then, one end of the connecting member 9 is placed on the current collecting electrode 4a of one solar cell element 1a, and the other end is placed on the back electrode 2b of the adjacent solar cell element 1b, and the connecting portion 7a of the connecting member 7 is soldered. Each of the solar cell elements 1a, 1b
To the current collecting electrode 4a and the back surface electrode 2b to form a solar cell module.

When sealing with a resin, the resin sheets 6a are arranged in parallel so as not to come on the connecting members 9 of the solar cell module, and are heated and compressed to perform resin sealing.

According to this configuration, the connecting portion 9 of the connecting member 9
By a, the solar cell elements 1a and 1b are connected on a plurality of connection surfaces separated from each other. Therefore,
The connection between the connection member 9 and the solar cell elements 1a, 1b is performed on a plurality of connection surfaces whose area is greatly reduced, and the stress accompanying thermal expansion to the solar cell elements 1a, 1b can be suppressed. .

However, in the configuration of this solar cell module, if the connecting member 9 is made of the same material, the connecting portion 9b needs to be bent. Also, the connecting portion 9a
If the connecting portion 9b is made of a different member, a joining process such as welding is required.

When such a connecting member 9 is used, the connecting portion 9b that is not connected to the solar cell elements 1a and 1b needs a physical distance that is not joined to the solar cell elements 1a and 1b even by the inflow of solder. In addition, processing of the connecting portion requires high precision so that the connecting portion is not exposed from the resin 6 after resin sealing.

In addition, the connecting member 9 is connected to the solar cell elements 1a, 1
In the assembling work before joining to the part b, it is necessary to perform the assembling work so that the connecting portion 9a and the connecting portion 9b are not deformed so as to cause the above problem.

In addition, the connection member 9 and the solar cell element 1 are protected against long-term temperature stress when used as a product.
Although there is a problem related to the connection with the connection members a and 1b, disconnection at the connection member 9 due to a difference in the coefficient of thermal expansion between the resin and the connection member 9 also poses a serious problem. In particular, in the connection member 9 shown in the conventional example, the strength of such a processed portion is increased by performing the above-described processing of the connecting portion 9b in order to separate from the connection surface of the solar cell elements 1a and 1b and the connection surface. Because of the decrease, the possibility of disconnection in this processed part becomes extremely high.

Although breakage of the solar cell elements 1a and 1b caused by long-term temperature stress during use of the product can reduce the conversion efficiency, disconnection of the connecting member 9 causes a fatal failure that stops output. Will be.

[0029]

In such a conventional solar cell module, if the tab wire 5 is used to connect the plurality of solar cell elements 1a and 1b in series, the connection between the tab line and the solar cell element is not possible. There is a problem that the solar electronic element is likely to be damaged by thermal stress generated at the time of solder connection or the like.

Further, in the connecting member 9 used for connection instead of the tab wire 5 proposed to solve the problem, high dimensional accuracy is required for processing the connecting portion 9b not connected to the solar cell element. Therefore, not only does the cost rise significantly, but attention must also be paid to handling in the manufacturing process.

In addition, when a temperature cycle stress is applied over a long period of time when the product is used, there is a problem in that the possibility of occurrence of disconnection in the joined or bent portion of the connecting portion 9b increases.

The present invention has been made in order to solve such a problem, and a thin metal plate similar to a tab wire is subjected to a surface treatment so that a plurality of solar cell elements can be connected at the time of soldering. It is an object of the present invention to obtain a solar cell module which can be damaged by damage of a solar cell element due to applied thermal stress and a long-term temperature cycle stress.

[0033]

SUMMARY OF THE INVENTION A solar cell module according to the present invention has a back electrode on the back surface, a plurality of solar cell elements having a front electrode and a collecting electrode on the front surface, and one solar cell element. And a solar cell module provided with a strip-shaped connection tab for connecting a current collecting electrode of one solar cell element and a back electrode of another adjacent solar cell element, which is provided for connecting the adjacent solar cell elements in series. The connection tab is provided with a plurality of solderable areas that can be soldered and non-soldering areas that cannot be soldered alternately in the longitudinal direction.

The non-soldering area of the connection tab is covered with a non-soldering metal.

Further, the non-soldering area of the connection tab is coated with a heat-resistant resin.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 A solar cell module according to an embodiment of the present invention will be described with reference to FIGS. FIGS. 1 to 3 show a solar cell module according to an embodiment of the present invention. FIG. 1 is a top view of a tab wire for connecting adjacent solar cell elements.
FIG. 2 is a sectional view taken along the line BB ′ in FIG. 1. FIG. 3 is a side view of the solar cell module using the tab wires shown in FIGS. 1 and 2.

In FIG. 3, reference numerals 1a and 1b denote a plurality of flat-plate-shaped solar cell elements, and 2a and 2b denote solar cell elements 1
Back electrodes 3a, 3b provided on the entire back surfaces of a, 1b
Are surface electrodes provided side by side at predetermined intervals on the surfaces of the solar cell elements 1a and 1b, and 4a and 4b are 3a and 4b, respectively.
The front electrode current collecting electrode 10 for connecting 3b is a connection tab for connecting the current collecting electrode 4a of one solar cell element 1a to the back electrode 3b of another adjacent solar cell element 1b. Also,
In the connection tab 10, 10 is a tab wire, 10a is a copper foil,
10b is a surface treatment, and 10c is a solder.

The present embodiment is different from the conventional structure in that the surface of the tab wire 10 for connecting the adjacent solar cell elements 1a, 1b, which is connected to the solar cell elements 1a, 1b, is entirely formed of solder. It does not have a structure to adhere, and is configured to partially adhere at a plurality of places. That is, the connection tab 10 is provided with a plurality of solderable areas 10c where soldering is possible and non-soldering areas where soldering is not performed, at predetermined intervals in the longitudinal direction. The point that the tab wire 10 is not mechanically bent or joined on the connection surface with the solar cell elements 1a and 1b.

In producing the tab wire 10 having such a configuration, specifically, a thin copper foil 10a serving as a base is used.
Then, after masking the places where the solder adheres partially at a plurality of places, apply a surface treatment 10b with a heat-resistant resin or chrome plating to which the solder does not adhere, then remove the masking and apply a preliminary solder 10c I do.

By using the tab wires 10 for connection of a plurality of solar cell elements 1a and 1b arranged in parallel, the connection area is reduced only to the area where the preliminary solder 10c is applied, so that the connection area can be easily reduced. And a tab line 10
Has a flat structure, which facilitates handling. In addition, since the tab wire 10 is not mechanically processed in the initial stage, there is no place where the mechanical strength is reduced.

That is, by connecting the tab wires 10 intermittently to the solar cell elements 1a and 1b, the thermal stress generated at the time of soldering is reduced by the parts not connected to the solar cell elements (the solder does not adhere). By reducing, the damage of the solar cell elements 1a and 1b can be suppressed. In addition, the possibility of causing damage to the solar cell elements 1a and 1b can be reduced even with long-term temperature stress in the final product form sealed with resin, and mechanical processing is performed on the tab wires. By doing so, it is possible to suppress the occurrence of problems such as disconnection due to stress caused by the temperature difference between the resin and the tab wire.

In this embodiment, chrome plating is used as a surface treatment of the tab wire 10. However, the same effect can be obtained by coating a resin such as urethane.

[0043]

According to the solar cell module of the present invention, a plurality of solar cell elements having a back surface electrode on the back surface, a front surface electrode and a current collecting electrode on the front surface are arranged side by side, A solar cell module having a band-shaped connection tab for connecting a current collecting electrode of one solar cell element and a back electrode of another adjacent solar cell element, provided for connecting the solar cell elements in series, The tab is provided with a plurality of solderable areas that can be soldered and non-soldering areas that cannot be soldered alternately in the longitudinal direction. Therefore, the connection surface between the solar cell element and the connection tab becomes intermittent, and the life can be improved with respect to the temperature cycle. Furthermore, since unnecessary mechanical processing is not performed on the connection tab, the life can be further improved with respect to a temperature cycle.

The unsoldering area of the connection tab is covered with a non-soldering metal. for that reason,
A non-soldering area can be reliably formed, and reliability is improved.

Further, the non-soldering area of the connection tab is coated with a heat-resistant resin. for that reason,
A non-soldering area can be reliably formed, and reliability is improved.

[Brief description of the drawings]

FIG. 1 is a top view of a tab line for connecting adjacent solar cell elements of a solar cell module of the present invention.

FIG. 2 is a sectional view taken along the line B-B 'of FIG.

FIG. 3 is a side view of the solar cell module using the tab wires shown in FIGS. 1 and 2.

FIG. 4 is a top view showing a connection state of a conventional solar cell module.

FIG. 5 is a side view of the solar cell module of FIG.

FIG. 6 is a sectional structural view of a conventional solar cell module.

FIG. 7 is a top view showing another connection state of a conventional solar cell element.

8 is a side view of the solar cell module of FIG.

FIG. 9 is a sectional structural view of a conventional solar cell module.

FIG. 10 is an exploded cross-sectional view when the solar cell element is sealed with a resin.

FIG. 11 is a sectional view taken along the line AA ′ in FIG. 10;

[Explanation of symbols]

1a, 1b solar cell element, 2a, 2b back electrode, 3
a, 3b front electrode, 4a, 4b current collecting electrode, 6 resin, 6a resin sheet, 7 front member, 8 back member,
9 connection member, 9a connection part, 9b connection part, 10 tab wire, 10a copper foil, 10b surface treatment (non-soldering area), 10c preliminary solder (soldering area).

Claims (3)

[Claims] A plurality of solar cell elements having a back surface electrode on a back surface and a front surface electrode and a current collecting electrode on a front surface are arranged in parallel.
A strip-shaped connection tab provided for connecting one solar cell element and another adjacent solar cell element in series, and connecting the current collecting electrode of one solar cell element and the back electrode of another adjacent solar cell element. Wherein the connection tab is provided with a plurality of solderable areas that can be soldered and non-soldering areas that cannot be soldered alternately in the longitudinal direction. A solar cell module characterized by the above-mentioned. 2. The solar cell module according to claim 1, wherein the non-soldering area of the connection tab is covered with a non-soldering metal. 3. The solar cell module according to claim 1, wherein a non-soldering area of the connection tab is coated with a heat-resistant resin.