JP2004281800A - Solar cell module - Google Patents

Abstract

An object of the present invention is to provide means for confirming a soldered state of an electrical connection inside a solar cell module.
A connection between a bus bar electrode (13) and a connection tab (15), a connection between a connection tab (15) and a horizontal connection line, and a connection between an output wiring from a solar cell element (12) and a terminal in a terminal box, respectively. A through-hole 16 is provided in the connection portion, and the state of the fillet of the solder formed in the periphery of the through-hole 16 is visually checked, thereby creating a highly reliable solar cell module with a completely soldered state.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a solar cell module in which a plurality of solar cell elements are connected by connection tabs.
[0002]
[Prior art]
Solar cell elements are often manufactured using a single crystal silicon substrate or a polycrystalline silicon substrate. For this reason, the solar cell element is vulnerable to physical impact, and when the solar cell is installed outdoors, it is necessary to protect it from rain etc. Therefore, the solar cell element is made of a translucent substrate and an ethylene vinyl acetate copolymer ( It is common practice to create a solar cell module by enclosing it with a filler mainly containing EVA) or the like.
[0003]
In this solar cell module, since one solar cell element has a small electric output, a plurality of solar cell elements are usually connected in series and parallel to generate a practical predetermined electric output from the solar cell module. .
[0004]
FIG. 5 is a diagram schematically showing wiring inside the solar cell module. In FIG. 5, 1 is a solar cell element, 2 is a connection tab, 3 is a horizontal connection line, 4 is a connection portion between the connection tab and the horizontal connection line, 5 is an output wiring from the solar cell element, 6 is Terminal box 7 indicates a terminal in the terminal box.
[0005]
The solar cell element 1 is often manufactured using a single crystal silicon substrate or a polycrystalline silicon substrate as described above. The connection tab 2 is usually used by cutting a solder-coated copper foil into a predetermined length. The connecting wires 3 in the horizontal direction are provided in order to match the vertical and horizontal dimensions of the solar cell module, and usually also use copper foil coated with solder. The output wiring 5 from the solar cell element connects the solar cell element 1 and the terminal 7 in the terminal box 6, and a copper foil which is similarly solder-coated is often used. The output wiring 5 of the solar cell element 1 and a cable (not shown) of an external circuit are connected to a terminal 7 in the terminal box 6. The terminal 7 in the terminal box 6 is formed by solder-coating a copper plate.
[0006]
As described above, in the electrical connection inside the solar cell module, the connection between the solar cell element 1 and the connection tab 2, the connection between the connection tab 2 and the horizontal connection line 3, and the output wiring 5 from the solar cell element 1. Also, in connection with the terminal 7 in the terminal box 6, the solder is often melted by hot air or the like using solder-coated copper foil for one or both of them.
[0007]
FIG. 6 is a diagram showing a cross section in which a connection tab is soldered to an electrode of a solar cell element. In FIG. 6, reference numeral 8 denotes an electrode (light receiving surface side or non-light receiving surface side) of the solar cell element, 9 denotes a connection tab, 10 denotes a fillet made of solder, and 11 denotes solder between the electrode of the solar cell element and the connection tab.
[0008]
The surface of the electrode 8 of the solar cell element is coated with solder 11, and a fillet 10 having a substantially triangular cross section is formed between the end of the connection tab 9 and the electrode 8 of the solar cell element.
[0009]
When connecting the connection tab 9 to the electrode 8 of the solar cell element, the solder on both surfaces is melted and soldered. In this case, the solder and the fillet 10 at the portion where the electrode 8 and the connection tab 9 are in contact with each other strengthen the adhesion, and can also reduce the electrical resistance at that portion.
[0010]
Prior art document information related to the invention of this application includes the following.
[0011]
[Patent Document 1]
Japanese Patent Application Laid-Open No. H11-313820
[Problems to be solved by the invention]
However, in the connection between the electrode 8 of the solar cell element and the connection tab 9, even if the fillet 10 is formed at both ends of the connection tab 9, the state of the soldering between the electrode 8 of the solar cell element and the connection tab 9 is the appearance. Could not confirm.
[0013]
For this reason, when connecting the electrode 8 and the connection tab 9, the soldering heat is insufficiently applied, or the connection tab 9 is lifted from the electrode 8. Even if the soldering state of the solder 11 during the period 9 was incomplete, it could not be found. When the soldering state of the solder 11 between the electrode 8 and the connection tab 9 of the solar cell element is incomplete, the connection strength between the connection tab 9 and the electrode 8 decreases, and the connection tab 9 peels off from the electrode 8 in a subsequent step. In some cases, the output of the solar cell module may decrease due to electrical resistance caused by incomplete soldering.
[0014]
This is not limited to the electrodes 8 and the connection tabs 9, but also the connection between the connection tabs 2 and the horizontal connection lines 3, and the connection between the output wiring 5 from the solar cell element and the terminal 7 in the terminal box 6. But it is common.
[0015]
The present invention has been made in view of such a problem, and an object of the present invention is to visually check a soldering state of a connection surface which cannot be confirmed from the outside in connection in a solar cell module using a copper foil or the like coated with solder. An object of the present invention is to provide a highly reliable solar cell module that can be confirmed.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a solar cell module in which a connection tab having a surface covered with solder is connected to electrodes of a plurality of solar cell elements and disposed between a light-transmitting substrate and a non-light-receiving surface sheet Wherein a through hole is provided at a connection portion of the connection tab with the electrode.
[0017]
Further, in a solar cell module in which a connection tab connected to a solar cell element is connected to a horizontal connection line, a connection portion of the connection tab with the horizontal connection line or the connection tab of the horizontal connection line. A through-hole is provided in a connection portion with the と.
[0018]
Further, in the solar cell module in which the output wiring connected to the solar cell element is connected to the terminal of the terminal box, a through hole is provided at a connection portion of the output wiring with the terminal or a connection portion of the terminal with the output wiring. It is characterized by having been done.
[0019]
Further, the connection portion provided with the through-hole is connected by solder containing substantially no lead.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram showing an example of a state where a connection tab is connected to a light receiving surface side of a solar cell element according to the present invention. In FIG. 1, 12 indicates a solar cell element, 13 indicates a bus bar electrode, 14 indicates a finger electrode, 15 indicates a connection tab, and 16 indicates a through hole provided in the connection tab.
[0021]
The solar cell element 12 is made of, for example, single-crystal silicon or polycrystalline silicon having a thickness of about 0.3 to 0.4 mm and a size of about 150 mm square. A PN junction in which a P layer containing a large amount of P-type impurities such as boron and an N layer containing a large amount of N-type impurities such as phosphorus is in contact is formed inside the solar cell element 12.
[0022]
The bus bar electrode 13 and the finger electrode 14 are formed by a screen printing method of silver paste or the like, and the surface of the bus bar electrode 13 is solder-coated over almost the entire surface of the bus bar electrode 13 to protect the bus bar electrode 13 and to easily attach the connection tab. . The finger electrodes 14 have a width of about 0.2 mm and are formed in a large number in parallel with the sides of the solar cell element in order to collect photo-generated carriers. The busbar electrodes 13 are formed so as to intersect perpendicularly with the finger electrodes 14 so as to intersect the finger electrodes 14 in order to collect the collected carriers, and have a width of about 2 mm in order to attach a connection tab.
[0023]
The connection tab 15 is formed of a copper foil having a thickness of about 100 to 300 μm and a solder coating of about 20 to 70 μm on the entire surface. The width thereof is equal to or less than the width of the bus bar electrode 13 so as not to form a shadow on the light receiving surface of the solar cell element by itself. The length thereof overlaps almost all of the bus bar electrodes 13, and further, overlaps with a predetermined interval between the solar cell elements and a non-light-receiving surface bus bar electrode (not shown) of the adjacent solar cell element by about 10 to 50 mm. When using a general 150 mm square polycrystalline silicon solar cell element, the width of the connection tab 15 is about 1 to 3 mm, and its length is about 160 to 210 mm. The reason why the connection tab 15 overlaps substantially all of the light-receiving-surface-side bus bar electrode 13 is to reduce the resistance component of the solar cell element.
[0024]
The connection tab 15 has a through hole 16. The through hole 16 is provided in advance at a portion where the connection tab 15 is connected to a non-light receiving surface bus bar electrode (not shown) of the solar cell element adjacent to the bus bar electrode 13. When a common 150 mm square polycrystalline silicon solar cell element is used, about 2 to 5 through holes 16 are connected to the busbar electrode 13, and the non-light-receiving surface busbar electrode (not shown) of the adjacent solar cell element is used. The connection tab 15 is provided with about 1 to 3 pieces by punching or the like, and the diameter thereof is optimally about half to one quarter of the width of the connection tab 15. Further, the through-hole 16 is not limited to a circle, but may be an ellipse, a square, a rectangle, or another polygon.
[0025]
FIG. 2 is a view showing a cross section of a through hole portion where a connection tab is soldered on a bus bar electrode. In FIG. 2, 13 is a bus bar electrode of the solar cell element, 15 is a connection tab, 16 is a through hole, and 17 is a fillet made of solder.
[0026]
The fillet 17 is formed not only at the end of the connection tab 15 but also at the periphery of the through hole 16. The presence or absence, size, and shape of the fillet 17 in the peripheral portion of the through hole 16 makes it possible to visually check the soldering state near the center of the bus bar electrode 13. That is, if the fillet 17 is formed so as to cover the end of the connection tab 15 and the periphery of the through hole 16, a good soldering state is obtained. For example, when the fillet 16 is not formed or is small, the soldering is performed. Can be determined to be incomplete.
[0027]
The connection between the solar cell elements 12 according to the present invention is performed as follows. First, the connection tab 15 provided with the through hole 16 at a predetermined position is arranged on the bus bar electrode 13 of the solar cell element 12. Hot air is blown while pressing the connection tab 15 with a pressing pin (not shown) to melt the solder of both the bus bar electrode 13 and the light receiving surface side connection tab 15 and connect them.
[0028]
FIG. 3 is a view showing an example of a connection state between the connection tab and the horizontal connection line according to the second aspect of the present invention. In FIG. 3, reference numeral 15 denotes a connection tab, 18 denotes a horizontal connection line, and 19 denotes a through hole provided in the connection tab 15.
[0029]
The connecting wires 18 in the horizontal direction have a width of about 3 to 10 mm and a thickness of about 100 to 300 μm, and are formed by solder coating on the entire surface of the copper foil. The through hole 19 provided in the connection tab 15 is provided by a method such as punching, and the diameter thereof is optimally about half to a quarter of the width of the connection tab 15. Further, the through hole 19 is not limited to a circle, but may be an ellipse, a square, a rectangle, or another polygon.
[0030]
The connection between the connection tab 15 and the horizontal connection line 18 is performed by arranging the connection tab 15 provided with a through hole 19 in a predetermined position on the connection line 18 and pressing the connection tab 15 with a holding pin (not shown). Hot air is blown while pressing to melt the solder of both the connection wire 18 and the light receiving surface side connection tab 15.
[0031]
In the connection between the connection tab 15 and the horizontal connection line 18 as well, by providing the through hole 19 at the connection portion of the connection tab 15, it is possible to confirm the soldering state by the fillet at this through hole 19 portion. Become.
[0032]
Also, in FIG. 3, an example in which the connection tab 14 is soldered on the horizontal connection line 18 has been described. However, when the horizontal connection line 18 is soldered on the connection tab 15, A through hole may be provided in the wire 18.
[0033]
FIG. 4 is a diagram showing an example of a connection state between the output wiring from the solar cell element according to the invention of claim 3 and the terminal in the terminal box. In FIG. 4, reference numeral 20 denotes a terminal in the terminal box, 21 denotes an output wiring from the solar cell element, and 22 denotes a through hole provided in the output wiring 21 from the solar cell element.
[0034]
The terminal 20 is a copper plate having a thickness of about 1 to 3 mm, a width of about 5 to 20 mm, and a length of about 30 to 70 mm, which is solder coated. The output wiring 21 from the solar cell element is a copper foil having a width of about 2 to 10 mm and a thickness of about 100 to 300 μm, which is solder coated on the surface. The through-hole 22 provided in the output wiring 21 is provided in a portion connected to the terminal 20 of the output wiring 21 by a method such as punching about one or two pieces, and has a diameter of half to a quarter of the width of the output wiring 21. One degree is optimal. Further, the through hole 22 is not limited to a circle, but may be an ellipse, a square, a rectangle, or another polygon.
[0035]
The connection between the terminal 20 and the output wiring 21 is performed by arranging the output wiring 21 provided with a through hole 22 in a predetermined position on the terminal 20 and holding the output wiring 21 with a holding pin (not shown) while applying hot air. Or by applying a soldering iron to melt the solder of both the terminal 20 and the output wiring 21.
[0036]
Also in the connection between the terminal 20 and the output wiring 21, by providing the through hole 22 at the connection portion of the output wiring 21, the soldering state can be confirmed by the fillet in the through hole 22. FIG. 4 shows an example in which the output wiring 21 is soldered on the terminal 20. However, even when the terminal 20 is soldered on the output wiring 21, the through hole 22 may be provided in the terminal 20.
[0037]
Furthermore, in recent years, in solar cell modules, solders that do not contain lead, which is a harmful substance, have been actively studied due to environmental issues, but solders that do not substantially contain lead contain lead such as conventional eutectic solder. Many have a higher melting point and lower wettability than solder. For example, eutectic solder having a composition of 63% tin and 37% lead has a melting point of 183 ° C and a spread test value indicating wettability of 91.5%. The melting point is 220 ° C. and the value of the spread test is 76.3% in the case of a solder having no composition containing 96.5% of tin, 3% of silver and 0.5% of copper. For this reason, when using solder which does not substantially contain lead, it is necessary to carefully control conditions such as soldering temperature and time, and it is also necessary to strictly check the finished state after soldering. The present invention is also effective for solder that does not substantially contain lead, since the soldering state can be visually confirmed in a state of a solder fillet formed around the through hole in each connection portion.
[0038]
The present invention is not limited to the above embodiment, and many modifications and changes can be made to the above embodiment within the scope of the present invention. For example, the solar cell element is not limited to a crystalline solar cell such as monocrystalline or polycrystalline silicon, but may be a solar cell module in which the internal electrical connection is soldered using a solder-coated metal foil or the like. If applicable.
[0039]
【The invention's effect】
As described above, according to the solar cell module of the present invention, the connection between the bus bar electrode and the connection tab, the connection between the connection tab and the horizontal connection line, the output wiring from the solar cell element and the inside of the terminal box. In the connection with the terminal, since the through holes are provided in the respective connection portions, it is possible to visually check the soldering state in the state of the solder fillet formed around the through holes. In addition, since the fillet is formed around the through hole, the area where the alloy layer is formed is increased, and the connection strength can be improved. Further, the tolerance of the stress due to the thickness of the solder at the fillet portion is increased, and the durability of the heat cycle can be improved. Thus, a highly reliable solar cell module can be manufactured.
[0040]
Furthermore, even for solder that does not substantially contain lead and is difficult to be soldered, the soldering state can be visually checked in the state of the solder fillet formed around the through hole of each connection part, which is particularly effective. is there.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a solar cell module according to the present invention.
FIG. 2 is a view showing a state in which a connection tab is soldered to an electrode of the solar cell module according to the present invention.
FIG. 3 is a view showing a connection state between a connection tab and a horizontal connection line of the solar cell module according to the present invention.
FIG. 4 is a diagram showing a connection state between output wirings and terminals of the solar cell module according to the present invention.
FIG. 5 is a diagram schematically showing wiring of a conventional solar cell module.
FIG. 6 is a diagram showing a conventional connection portion between an electrode and a connection tab.
[Explanation of symbols]
1, 12; solar cell element, 2, 9, 15; connection tab, 3, 18; horizontal connection line, 4; connection portion between connection tab and horizontal connection line, 5, 21, output wiring, 6 Terminal box, 7, 20; terminal, 8; electrode, 10, 17; fillet, 11; solder, 13; busbar electrode, 14; finger electrode, 16, 19, 22;

Claims (4)

In a solar cell module in which a connection tab whose surface is covered with solder is connected to electrodes of a plurality of solar cell elements and disposed between a light-transmitting substrate and a non-light-receiving surface sheet, the connection of the connection tab to the electrode A solar cell module, wherein a through-hole is provided in a portion. In a solar cell module in which a connection tab connected to a solar cell element is connected to a horizontal connection line, a connection portion of the connection tab with the horizontal connection line or a connection portion of the horizontal connection line with the connection tab. A solar cell module, wherein a through hole is provided in a connection portion. In a solar cell module in which an output wiring connected to a solar cell element is connected to a terminal of a terminal box, a through-hole is provided in a connection part of the output wiring with the terminal or a connection part of the terminal with the output wiring. A solar cell module. The solar cell module according to any one of claims 1 to 3, wherein the connection portions provided with the through holes are connected by solder containing substantially no lead.

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