JP3754208B2 - Solar cell module and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for improving the yield of a solar cell module.
[0002]
[Prior art]
Solar cells are expected as new energy sources because they can directly convert light from the sun, which is a clean and inexhaustible energy source, into electricity.
[0003]
When such a solar cell is used as a power source for a house or a building, since the output per solar cell is as small as about several watts, a plurality of solar cells are usually electrically connected in series or in parallel. It is used as a solar cell module whose output is increased to several hundred W.
[0004]
FIG. 3 is a structural sectional view of such a conventional solar cell module. For example, a plurality of solar cells 1 made of single crystal silicon having a pn junction inside are electrically connected to each other by connection tabs 2 made of a conductive material such as copper foil. Between the surface member 3 having light transmissivity such as glass and light transmissible plastic and the back member 4 made of an aluminum foil sandwich-type vinyl fluoride film. It is sealed with a sealing material 5.
[0005]
By the way, such a solar cell module is usually manufactured through the following steps.
[0006]
4A and 4B are diagrams showing an example of a solar cell used in a normal solar cell module, where FIG. 4A is a cross-sectional structure diagram, and FIG. 4B is a plan view.
[0007]
In the figure, reference numeral 11 denotes a single crystal silicon substrate having p-type conductivity. An n layer 12 is formed on the surface of the substrate 11 to a depth of about 5 μm by thermally diffusing n-type impurities, and a comb-shaped collector electrode 13 is formed on the n layer 12. Has been. A back electrode 14 that forms a pair with the collector electrode 13 is formed on the back surface of the substrate 11.
[0008]
Referring to FIG. 5B, the collector electrode 13 includes a finger portion 13A for collecting photogenerated carriers of electrons and holes generated in the substrate 11 by the incidence of light, and a finger portion 13A. It comprises a bus bar portion 13B for collecting the collected carriers.
[0009]
Here, the collector electrode 13 blocks light incident on the solar cell and contributes to a reduction in the effective area of the solar cell. Therefore, it is desirable to make the area as small as possible. For this reason, normally, the width of the finger portions 13A is about 100 μm, and the interval between the finger portions 13A is about 2 mm. Further, since the bus bar portion 13B collects the carriers collected by the finger portions 13A, it is necessary to reduce the resistance component to some extent. For this reason, the width is about 1.5 mm, which is wider than the finger portions 13A. Is set. The collector electrode 13 having the finger portions 13A and the bus bar portions 13B is formed to a thickness of about 40 μm by screen printing.
[0010]
Next, FIG. 5 is a diagram showing a state in which solar cells having such a structure are connected to each other by the connection tab 2, wherein FIG. 5A is a cross-sectional view and FIG. 5B is a plan view. In the figure, parts having the same configuration as in FIGS. 3 and 4 are given the same reference numerals, and as shown in FIG. The bus bar portion 13 </ b> B in the electrode 13 and the back electrode 14 of the other solar cell 1 are electrically connected to each other by being connected by the connection tab 2.
[0011]
As the connection tab 2, there is usually used a thin plate-like metal having a thickness of about 100 μm, such as copper foil, with solder attached to both surfaces. In addition, the width is slightly narrower than the width of the bus bar portion 13B. When the width of the bus bar portion 13B is about 1.5 mm as described above, the width of the connection tab 2 is about 1 mm. The Then, in a state where this connection tab 2 is superimposed on the bus bar portion 13B of one solar cell 1, it is heated by hot air or lamp heating to a temperature equal to or higher than the melting temperature of the solder, for example, about 190 ° C. The tab 2 and the bus bar portion 13B are connected.
[0012]
Similarly, the solder is heated and melted in a state where the connection tab 2 is superposed on the back electrode 14 to connect the both to the back electrode 14.
[0013]
And the several solar cell manufactured by the above process and mutually electrically connected by the connection tab 2 is made into a solar cell module by a thermocompression bonding method using the laminating apparatus shown in FIG.
[0014]
In FIG. 6, reference numeral 21 denotes a lower housing, 22 denotes a heat plate built in the lower housing 21, and a heater is incorporated in the lower housing 21 via an O-ring 24. A casing 25 is a diaphragm provided in the upper casing 23, and partitions a space formed between the lower casing 21 and the upper casing 23 into a lower chamber 26 and an upper chamber 27.
[0015]
In addition, 28 is a vacuum pump for evacuation, 29 is connected to the vacuum pump 28, a lower chamber pipe communicating with the lower chamber 26, 30 is connected to the vacuum pump 28 via a vacuum valve 31, and communicates with the upper chamber 27 The upper chamber pipe 32 is an atmospheric pipe having one end open to the atmosphere and the other end communicating with the upper chamber 27 via the atmospheric valve 33.
[0016]
And the laminated body by which the back surface member, the sealing material sheet | seat consisting of EVA, the several solar cell connected by the connection tab, the sealing material sheet | seat consisting of EVA, and the surface member are laminated | stacked on the hot plate 22 one by one. 20 is mounted, the upper housing 23 is airtightly attached to the lower housing 21 via the O-ring 24, and the atmospheric valve 33 of the atmospheric pipe 32 is closed.
[0017]
Next, the vacuum valve 31 of the upper chamber pipe 30 is opened, the vacuum pump 28 is operated, and the upper chamber 27 and the lower chamber 26 are exhausted to a vacuum state via the upper chamber pipe 30 and the lower chamber pipe 29.
[0018]
Then, the heater of the hot plate 22 is energized to heat the laminate 20 to a temperature of about 150 ° C. In this state, the vacuum valve 31 of the upper chamber pipe 30 is closed and the atmospheric valve 33 of the atmospheric pressure pipe 32 is opened. The inside of the upper chamber 27 is brought to atmospheric pressure. Then, the diaphragm 25 bends due to the pressure difference between the upper chamber 27 and the lower chamber 26, presses the laminated body 20 in a heated state, and the two sealing material sheets in the laminated body 20 are in a softened state and become a plurality of A solar cell module having the configuration shown in FIG. 3 is manufactured by sealing the solar cell between the front surface member and the back surface member.
[0019]
[Problems to be solved by the invention]
By the way, in the solar cell using the above conventional crystalline silicon substrate, a silicon substrate having a thickness of about 400 μm to 500 μm was usually used. However, in recent years, the thickness of the silicon substrate has been reduced due to a demand for cost reduction, It has been studied to use a silicon substrate having a thickness of about 150 to 300 μm or less.
[0020]
However, in the case of using such a thin silicon substrate, there is a problem that the substrate is easily damaged when the solar cells are connected to each other by the connection tab. That is, since the connection tab is made of a metal such as copper foil, the coefficient of thermal expansion is larger than that of the silicon substrate. For this reason, in the conventional method of connecting the connection tab by heating to about 190 ° C., stress is applied to the substrate due to the difference in thermal expansion coefficient between the connection tab and the substrate when the temperature returns to room temperature. And since the tolerance of this board | substrate with respect to this stress falls, so that the thickness of a board | substrate becomes thin, when the silicon substrate thinner than before was used, it was easy to be damaged.
[0021]
Furthermore, when the thickness of the substrate is about 150 to 300 μm, the thickness of the connection tab is substantially equal to the thickness of the substrate. For this reason, when manufacturing a solar cell module by heat compression, a pressing force is locally applied to the connection tab. However, since the thickness of the substrate is thin, there is a problem that the substrate is more easily damaged than before.
[0022]
Accordingly, an object of the present invention is to solve such problems and to provide a solar cell module with good yield even when a crystalline silicon substrate having a thickness smaller than usual is used.
[0023]
[Means for Solving the Problems]
In order to solve such a problem, the solar cell module of the present invention seals a plurality of solar cells electrically connected to each other by a connection tab between a translucent surface member and a back surface member. The connection tab includes a plurality of connection portions that are separated from each other and form a connection surface with the solar cell, and a connection portion that connects the plurality of connection portions to each other. The connection tab is connected to the collector electrode in one solar cell of the adjacent solar cells among the plurality of solar cells and the back electrode in the other solar cell at the plurality of connection portions. And
[0024]
Also, the production method of the present invention the solar cell module, the rear surface member, the encapsulant sheet, a plurality of solar cells electrically connected to each other by a connecting tab, the encapsulant sheet, and the surface member is formed by stacking laminated A method of manufacturing a solar cell module, wherein a plurality of solar cells are sealed between the front and back members by heating and compressing a body, wherein the connection tabs are separated from each other and a connection surface with the solar cell is provided. A plurality of connecting portions to be formed; and a connecting portion that connects the plurality of connecting portions to each other; and the connection tabs are collector electrodes in one solar cell of adjacent solar cells among the plurality of solar cells; to the back electrode in the other solar cell, as well as connecting a plurality of the connecting portions, as the sealing material sheet, characterized by using a sheet portion corresponding to said connection tab is removed
[0025]
Alternatively, the plurality of solar cells can be formed by heating and compressing a laminate in which a back member, a sealing material sheet, a plurality of solar cells electrically connected to each other by a connection tab, a sealing material sheet, and a surface member are stacked. A method of manufacturing a solar cell module for sealing a battery between the front surface and the back surface member, wherein the connection tabs are separated from each other and form a connection surface with the solar cell, and the plurality of connection tabs A connecting portion that connects the connecting portions to each other, and a plurality of the connecting tabs are provided on a collecting electrode in one solar cell of adjacent solar cells among the plurality of solar cells and a back electrode in the other solar cell. In addition, a sheet having a thickness corresponding to the connection tab that is thinner than other portions is used as the sealing material sheet.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
A solar cell module according to a first embodiment of the present invention will be described with reference to FIG.
[0028]
FIG. 1 is a cross-sectional view showing a state where adjacent solar cells 1 and 1 are connected by a connection tab 2. In the figure, the same parts as those shown in FIG.
[0029]
5 is different from the conventional structure shown in FIG. 5 in that the connection tabs 2 are not plate-shaped as in the prior art, but are separated from each other, and on the bus bar portion 13B and the back electrode 14, the connection surface with the solar cell 1 It is in the point provided with the structure provided with several connection part 2A which has a flat surface for forming. The plurality of connecting portions 2A are connected to each other by connecting portions 2B that are separated from the connecting surface with the solar cell by rising from the connecting surface with the solar cell.
[0030]
That is, according to the present embodiment, the solar cell 1 is connected to a plurality of connection surfaces separated from each other, which are formed by the connection portion 2A of the connection tab 2. Therefore, according to such a configuration, the connection tab and the solar cell are connected to each other on a plurality of connection surfaces whose areas are greatly reduced as compared with the conventional case. Damage to the substrate 1 can be suppressed.
[0031]
That is, when the solar cell 1 and the connection tab 2 are connected, since they are heated to about 190 ° C. as described above, both of them thermally expand. At this time, the connection tab 2 having a large coefficient of thermal expansion. The degree of expansion is greater. And even when the solar cell 1 and the connection tab 2 connected in an expanded state return to room temperature, the connection tab 2 having a larger coefficient of thermal expansion has a larger contraction amount. For this reason, stress is applied to the solar cell 1, but according to the present invention, only the connecting portion 2A forms a connection surface between the connection tab 2 and the solar cell 1, and a plurality of connection surfaces are connected. The parts 2B are separated from each other. Therefore, since the connection between each connection tab 2 and the solar cell 1 is performed on a plurality of connection surfaces having an area of about a fraction of the conventional size, the stress applied to the solar cell 1 is reduced as compared with the conventional case. The solar cell 1 can be prevented from being damaged.
Example 1
Next, examples of the present invention will be described.
[0032]
In this example, p-type single crystal silicon having a size of 10 cm × 10 cm and a thickness of about 150 μm was used as the substrate 11 of the solar cell 1. The substrate 1 was heated to about 700 ° C. in a POCl ₃ atmosphere, and P (phosphorus), which is an n-type impurity, was thermally diffused to a depth of about 5 μm on the surface of the substrate 1 to form an n layer 12.
[0033]
Next, a collector electrode 13 was formed on the n layer 12 by screen printing using Ag paste, and a back electrode 14 was formed on the entire back surface of the substrate 1 using Al paste. An antireflection film made of TiO ₂ , SiN or the like may be formed on the collector electrode 13.
[0034]
Then, one end of the connection tab 2 is superimposed on the bus bar portion 13B of the collector electrode 13 of the solar cell 1 formed in this way over a length of about 8 cm.
[0035]
As the connection tab 2, as described above, a plate-like copper foil having a thickness of about 100 μm and having solder attached to both sides is used, and the shape of the connection tab 2 </ b> A is about 5 mm long, and the length is about 1 mm and the height is about 1 mm. It was set as the shape provided with the connection part 2B which rose to about 100 micrometers. The connection tab 2 having such a shape can be easily formed by passing a plate-like conventional connection tab between a pair of rollers provided with projections having a shape corresponding to the connecting portion 2B.
[0036]
Then, the solder attached to the connection tab 2 was melted while heating the connection tab 2 to a temperature of about 190 ° C. on the bus bar portion 13B, and the connection tab 2 was connected to the bus bar portion 13B.
[0037]
Therefore, according to the present embodiment, the connection between the solar cell 1 and the connection tab 2 is performed on a plurality of connection surfaces having a length of about 5 mm with an interval of about 1 mm in length. .
[0038]
Next, the other end of the connection tab 2 having the same configuration is superimposed on the back electrode 14 of the other solar cell 1 over a length of about 8 cm, and the solder attached to the connection tab 2 is melted to connect the connection tab 2. Was connected to the back electrode 14.
[0039]
And 20 sets of solar cells electrically connected by the connection tab 2 as described above were manufactured, and when the state was visually confirmed, there was no damage.
[0040]
On the other hand, 20 sets of solar cells electrically connected by conventional plate-like connection tabs using the same process were manufactured, and when the state was visually confirmed, 4 sets were damaged. there were.
[0041]
As described above, according to the invention according to the present embodiment, it is possible to provide a solar cell module with improved yield.
[0042]
In this embodiment, a connection tab having a connection portion length of about 5 mm and a connection portion length of about 1 mm that forms a connection surface with the solar cell is used. This is not limited to this. At least the length of the connecting portion may be about half the length of the overlapping of the connecting tab and the solar cell. In addition, the length of the connecting portion is such that the influence of thermal stress generated between the solar cell and the connection tab on one connection surface among the connection surfaces formed at adjacent connection portions is affected by the other connection surface. For this purpose, it is sufficient that the length is about 0.5 mm or more.
(Second Embodiment)
Next, the manufacturing method of the solar cell module which concerns on the 2nd Embodiment of this invention is demonstrated.
[0043]
Although it is as above-mentioned that the damage of the solar cell at the time of connection of a connection tab can be suppressed by making the shape of a connection tab into the shape described in 1st Embodiment, when using the board | substrate with reduced thickness, it is a laminate. It is also necessary to take into account damage at times.
[0044]
In the present embodiment, the purpose is to suppress such damage during lamination, and the present embodiment will be described with reference to the exploded sectional view shown in FIG. In addition, the same figure (B) is sectional drawing of the AA in (A).
[0045]
As described above, at the time of laminating, the back member 4, the sealing material sheet 5 ′ made of EVA, the plurality of solar cells 1 connected by the connection tab 2, the sealing material sheet 5 ′ made of EVA, and the surface member 3 In the present embodiment, a sheet from which a portion corresponding to the connection tab 2 is removed is used as the sealing material sheet 5 ′. ing.
[0046]
And the laminated body laminated | stacked in this way is pressed in the state heated to about 150 degreeC, and it is set as a solar cell module, but according to this embodiment, it seals in the part corresponding to the connection tab 2 at this time There is no material sheet. Therefore, the pressing force is not directly applied to the connection tab 2 at the initial stage of heating and compression, and the sealing material leaches out on the connection tab 2 as the sealing material sheet is softened, and the entire solar cell Is sealed with the sealing material 5, and a solar cell module is manufactured.
[0047]
Therefore, according to this Embodiment, since it can suppress that a pressing force is directly applied to the connection tab 2 part, it becomes possible to reduce the damage of the solar cell at the time of lamination.
(Example 2)
Next, examples of the present embodiment will be described.
[0048]
First, a sealing material sheet 5 ′ made of EVA having a thickness of about 0.6 mm is laminated on the back member 4 made of an aluminum foil sandwich-type vinyl fluoride film. This encapsulant sheet 5 ′ corresponds to the back side of the solar cell 1, but in this example, as described above, a connection tab having a width of about 1 mm was used. 'Has been removed over a width of about 1.2 mm in the region corresponding to the connecting tab 2.
[0049]
And on this sealing material sheet 5 ′, a plurality of solar cells 1 electrically connected to each other by the connection tab 2, the sealing material sheet 5 ′ from which the region corresponding to the connection tab 2 has been removed, and the glass The surface member 3 to be formed is laminated. Here, as the connection tab 2, the connection tab according to the first embodiment is used.
[0050]
Further, in this embodiment, glass is used as the front member 3 and an aluminum foil sandwich type vinyl fluoride film is used as the back member 4, but the present invention is not limited to this, and the front member is a translucent material such as PET, acrylic, polycarbonate or the like. Resin may be used, and a weather resistant material such as glass or resin may be used as the back member.
[0051]
Furthermore, the laminate formed by laminating the back surface member 4, the sealing material sheet 5 ′, the plurality of solar cells 1, the sealing material sheet 5 ′, and the surface member 3 in this way is shown in FIG. Was heated and compressed to produce a solar cell module.
[0052]
Thus, when 20 solar cell modules were manufactured and the damage of the solar cell 1 was confirmed visually, there was no thing damaged.
[0053]
On the other hand, in the solar cell module that uses the connection tab according to Embodiment 1 as the connection tab and is manufactured by a conventional method, the substrate 11 of the solar cell 1 is thin and is damaged during the laminating process. It was easy, and there was one sheet that was confirmed to be damaged by visual observation after 20 sheets were manufactured.
[0054]
Furthermore, in the solar cell module manufactured using the conventional plate-like connection tab as the connection tab and manufactured by the conventional method, damage to the solar cell was confirmed in 7 of the 20 solar cell modules manufactured. It was.
[0055]
Therefore, according to the present embodiment, it is possible to reduce the pressing force applied to the connection tab 2 on the solar cell 1 during heating and compression, and it is possible to suppress damage to the solar cell 1 during lamination.
[0056]
In this embodiment, the sheet from which the portion corresponding to the connection tab is removed is used as the sealing material sheet made of EVA. However, the present invention is not limited to this, and the portion corresponding to the connection tab is thinner than the other portions. The same effect can be obtained even if the used sheet is used. Moreover, you may make it arrange | position several sealing material sheets used as strip shape except the part corresponding to a connection tab.
[0057]
Furthermore, the present invention can be applied to solar cells having other structures using a crystalline semiconductor as a substrate, for example, a solar cell module using a solar cell having a structure in which a semiconductor junction is formed by a crystalline substrate and an amorphous semiconductor. it can.
[0058]
【The invention's effect】
As described above, according to the solar cell module of the present invention, since the connection tab is connected to the solar cell at a plurality of connection surfaces separated from each other, the influence of thermal stress at the time of connection can be reduced, It becomes possible to suppress damage to the solar cell. Therefore, a solar cell module with improved yield can be provided.
[0059]
Moreover, according to the method for manufacturing the solar cell module of the present invention, since the sealing material sheet from which the portion corresponding to the connection tab is removed or thinner than the other portion is used, the solar cell at the time of lamination The pressing force can be reduced, and damage to the solar cell can be suppressed. Therefore, the yield of the solar cell module can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a connection state between a solar cell and a connection tab according to a solar cell module of the present invention.
FIG. 2 is an exploded cross-sectional view according to a method for manufacturing a solar cell module of the present invention.
FIG. 3 is a cross-sectional view of a conventional solar cell module.
FIG. 4 is a structural diagram of a conventional solar cell.
FIG. 5 is a state diagram showing a connection state between a conventional solar cell and a connection tab.
FIG. 6 is a configuration diagram of a laminating apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Solar cell, 2 ... Connection tab, 3 ... Front surface member, 4 ... Back surface member, 5 ... Sealing material 11 ... Substrate, 12 ... N layer, 13 ... Collector electrode, 13A ... Finger part,
13B ... Bus bar part, 14 ... Back electrode

Claims (3)

A solar cell module in which a plurality of solar cells electrically connected to each other by a connection tab are sealed between a surface member having translucency and a back surface member,
The connection tab includes a plurality of connection portions that are separated from each other and form a connection surface with the solar cell, and a connection portion that connects the plurality of connection portions to each other.
And the said connection tab is connected to the current collection electrode in one solar cell of the solar cells which adjoin among the plurality of solar cells, and the back electrode in the other solar cell by a plurality of said connection parts. Solar cell module. A plurality of solar cells electrically connected to each other by a back member, a sealing material sheet, a connection tab, a sealing material sheet, and a laminate formed by laminating a surface member are heated and compressed to form the plurality of solar cells. A method for producing a solar cell module for sealing between the front and back members,
The connection tab includes a plurality of connection portions that are separated from each other and form a connection surface with the solar cell, and a connection portion that connects the plurality of connection portions to each other.
The connection tab is connected to the collector electrode in one solar cell of the adjacent solar cells among the plurality of solar cells, and the back electrode in the other solar cell at the plurality of connection portions,
A method for manufacturing a solar cell module, wherein a sheet from which a portion corresponding to the connection tab is removed is used as the sealing material sheet. A plurality of solar cells electrically connected to each other by a back member, a sealing material sheet, a connection tab, a sealing material sheet, and a laminate formed by laminating a surface member are heated and compressed to form the plurality of solar cells. A method for producing a solar cell module for sealing between the front and back members,
The connection tab includes a plurality of connection portions that are separated from each other and form a connection surface with the solar cell, and a connection portion that connects the plurality of connection portions to each other.
The connection tab is connected to the collector electrode in one solar cell of the adjacent solar cells among the plurality of solar cells, and the back electrode in the other solar cell at the plurality of connection portions,
A method for manufacturing a solar cell module, wherein a sheet having a thickness corresponding to the connection tab is made thinner than the other portion is used as the sealing material sheet.

Images