JP4210124B2 - Solar cell element and solar cell module - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solar cell element including a light receiving surface side bus bar electrode and a non-light receiving surface side bus bar electrode for connecting a plurality of solar cell elements in series and parallel, and a solar cell module using the solar cell element.
[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 attached outdoors, it is necessary to protect it from rain. Moreover, since the electrical output generated by one solar cell element is small, it is necessary to connect a plurality of solar cell elements in series and parallel so that a practical electrical output can be taken out. For this reason, a solar cell module is usually formed by connecting a plurality of solar cell elements and enclosing with a filler mainly composed of a light-transmitting substrate and an ethylene vinyl acetate copolymer (EVA). .
[0003]
The method of connecting a plurality of solar cell elements is to heat the solder tab to a temperature equal to or higher than the melting temperature of the solder in a state where a connection tab made of solder foil on a copper foil or the like is superimposed on the light receiving surface side electrode of the solder-coated solar cell element. Then, the connection tab solder and the electrode solder are welded together.
[0004]
FIG. 5 is a view of the light receiving surface side of two solar cell elements connected in series with a connection tab. In FIG. 5, 1 and 2 are solar cell elements, 3 and 4 are surface side bus-bar electrodes, 5 and 6 are connection tabs, and 7 is a surface-side finger electrode.
[0005]
The solar cell elements 1 and 2 have the following structure. An N-type impurity diffusion layer is formed by thermally diffusing an N-type impurity such as phosphorus on one main surface of a single-crystal silicon or polycrystalline silicon P-type substrate having a thickness of about 0.3 mm and a size of about 150 mm square. By baking P-type impurities such as aluminum on the other main surface, a high concentration P-type impurity diffusion layer is formed. In addition, in order to suppress the reflection of light on the N-type impurity diffusion layer serving as the light receiving surface, an antireflection film is formed with silicon nitride or the like, and then silver paste is screen printed on the light receiving surface side and the non-light receiving surface side. An electrode is formed.
[0006]
There are bus bar electrodes and finger electrodes on the light receiving surface side and the non-light receiving surface side. For example, on the light receiving surface, in order to collect photogenerated carriers, a large number of finger electrodes 7 having a width of about 0.2 mm and parallel to the sides of the solar cell element are formed. The bus bar electrodes 3 and 4 are formed to have a width of about 2 mm and to intersect the finger electrodes 7 perpendicularly to collect the collected carriers and attach the connection tabs.
[0007]
The light receiving surface side bus bar electrodes 3 and 4 and the non-light receiving surface side bus bar electrodes (not shown) are provided in the same direction (parallel). Finally, in order to protect the electrodes and make it easy to attach the connection tabs, the surfaces of all the electrodes 3, 4, 7 are solder coated. The solar cell element thus produced has a light receiving surface on the negative side and a back surface on the positive side.
[0008]
The connection tabs 5 and 6 are obtained by cutting a copper foil having a thickness of about 0.1 mm and a width of about 2 mm and soldering the entire surface thereof to a predetermined length.
[0009]
FIG. 6 is a diagram showing a conventional solar cell module, in which eight solar cell elements 8 are arranged in two rows and are connected in series as viewed from the non-light-receiving surface side. In FIG. 6, 8 is a solar cell element, 9 is a connection tab connected to the solar cell element, and 10 is a horizontal wiring for further connecting in series two rows of four solar cell elements connected in series. .
[0010]
FIG. 7 is an enlarged view showing a portion of the horizontal wiring 10. In FIG. 7, 8 is a solar cell element, 10 is a horizontal wiring, 11 is a connection tab connected to the surface of the solar cell element, and 12 is a connection tab connected to the back surface of the solar cell element.
[0011]
The horizontal wiring 10 uses a copper foil coated with solder in the same manner as the connection tabs 11 and 12. The connection tab 11 connected to the surface of the solar cell element and the connection tab 12 connected to the back surface of the solar cell element are superposed on the horizontal wiring 10 and the solder on each surface is melted and soldered. (For example, refer to Patent Document 1).
[0012]
Prior art document information related to the invention of this application includes the following.
[0013]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-319691
[Problems to be solved by the invention]
However, in the conventional method for connecting solar cell elements, as shown in FIG. 6, since there is a horizontal wiring 10 at the end of the solar cell module, the horizontal wiring 10 should be performed in addition to arranging the required number of solar cell elements 8. There is a problem that a portion is necessary and the size of the solar cell module becomes larger than necessary.
[0015]
For this reason, there is a problem that the power generation efficiency of the solar cell module is reduced, and a large member such as glass is required, which leads to an increase in cost and further increases its weight.
[0016]
Further, when the horizontal wiring 10 is present, there is a problem that light is reflected by the metal of the horizontal wiring 10 and the appearance of the solar cell module is impaired.
[0017]
The present invention has been made in view of such conventional problems, and by reducing the size of the solar cell module by eliminating the horizontal wiring and improving the power generation efficiency, the cost is reduced and the weight is reduced. Furthermore, it aims at providing the solar cell module which looked good.
[0019]
The solar cell element according to claim 1 is a solar cell element in which a light-receiving surface side bus bar electrode and a non-light-receiving surface side bus bar electrode electrically connected to the connection tab are provided on the light receiving surface and the non-light receiving surface. The non-light receiving surface side bus bar electrode is provided in a direction parallel to and perpendicular to the light receiving surface side bus bar electrode.
[0020]
Furthermore, in the solar cell module which concerns on Claim 2 , it is a solar cell module which has a module part provided with two or more solar cell elements of Claim 1 , Comprising: One solar cell element in the corner | angular part of the said module part, The other solar cell element adjacent to the one solar cell element is parallel to the light receiving surface side bus bar electrode of the one solar cell element and the light receiving surface side bus bar electrode of the one solar cell element. The non-light-receiving surface side bus bar electrode of the other solar cell element provided is connected by a connection tab .
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The configuration of the solar cell element of the present invention is substantially the same as that of a conventional solar cell element. That is, an N-type impurity diffusion layer is formed by thermally diffusing N-type impurities such as phosphorus on one main surface of a single-crystal silicon or polycrystalline silicon P-type substrate having a thickness of about 0.3 mm and a size of about 150 mm square. Further, a high-concentration P-type impurity diffusion layer is formed by baking P-type impurities such as aluminum on the other main surface. In addition, in order to suppress the reflection of light on the N-type impurity diffusion layer serving as the light receiving surface, an antireflection film is formed with silicon nitride or the like, and then silver paste is screen printed on the light receiving surface side and the non-light receiving surface side. An electrode is formed.
[0022]
There are bus bar electrodes and finger electrodes on the light receiving surface side and the non-light receiving surface side. For example, on the light receiving surface, a plurality of finger electrodes 7 having a width of about 0.2 mm are formed in parallel with the sides of the solar cell element. The bus bar electrodes 3 and 4 are formed to collect the collected carriers and have a width of about 2 mm so as to attach the connection tabs, and two or three bus bar electrodes 3 and 4 are formed so as to intersect the finger electrodes 7 vertically.
[0023]
In addition, a plurality of solar cell elements are heated to a temperature equal to or higher than the melting temperature of the solder in a state where the connection tab solder-coated on copper foil or the like is superimposed on the solder-coated electrode on the surface of the solar cell element. The solder is connected to the electrode by welding. In this way, a plurality of solar cell elements are connected, and sealed with a filler mainly composed of a light-transmitting substrate and an ethylene vinyl acetate copolymer (EVA), thereby producing a solar cell module.
[0024]
FIG. 1 is a view of a state in which solar cell elements according to the present invention are connected in series in two rows, as viewed from the non-light-receiving surface side. FIG. 2 is a diagram showing a connection state on the surface side of two adjacent solar cell elements in the upper part of FIG. FIG. 3 is a diagram showing the state of the back surface of the two solar cell elements shown in FIG. 1, 2, and 3, 13 is a solar cell element, 14 is a connection tab, 15 is a non-light-receiving surface side bus bar electrode, and 16 is a light receiving surface side bus bar electrode.
[0025]
As shown in FIG. 1, the six solar cell elements 13 except the two solar cell elements 13a and 13b at the top are not connected to the solar cell elements 13 in the horizontal direction, and are only in the vertical direction. Connection to the element 13 is made. For this reason, the connection of the six solar cell elements 13 requires that the light receiving surface side bus bar electrode 16 and the non-light receiving surface side bus bar electrode 15 have the same direction (parallel).
[0026]
However, the two solar cell elements 13a and 13b at the top of FIG. 1 need to be connected to the solar cell elements 13a and 13b in the lateral direction. In connection with the solar cell elements 13a and 13b in the lateral direction, as shown in FIGS. 2 and 3, the light receiving surface side bus bar electrode 16 of the solar cell elements 13a and 13b and the non-light receiving surface side bus bar electrode 15a in the vertical direction are connected. This is done by connecting the tab 14.
[0027]
The method of connection is to melt the solder on both surfaces while holding the connection tab 14 with a soldering iron or the like that is placed on the light receiving surface side bus bar electrode 16 of the solar cell element 13 and heated to a predetermined temperature. Connecting. Further, the other end of the connection tab 14 is placed on the non-light-receiving surface side bus bar electrode 15a of the other solar cell element 13a to be connected, and the solder is melted and soldered in the same manner. To do.
[0028]
FIG. 4 is a view showing another embodiment of the present invention, as seen from the back side of the solar cell element. In FIG. 4, 17 (17a, 17b) is a solar cell element, 18 is a non-light-receiving surface side bus bar electrode, and 19 is a connection tab.
[0029]
As shown in FIG. 4, the non-light-receiving surface side bus bar electrode 18 of the solar cell element 17a is not in the shape of a well as shown in FIG. 3, but is only perpendicular to the light receiving surface side bus bar electrode (not shown). Yes. This is used only for the solar cell element 17 in the portion where the horizontal wiring of the solar cell module is necessary. For the other portions, those in which the directions of the normal light receiving surface side bus bar electrode and the non-light receiving surface side bus bar electrode 18 are parallel are used.
[0030]
In the connection with the solar cell element 17b in the lateral direction, as shown in FIG. 4, the light-receiving surface side bus bar electrode 18 of the solar cell element 17b adjacent to the light-receiving surface side bus bar electrode of the solar cell element 17a This is done by connecting the connection tab 19.
[0031]
As a result, there is an advantage that less electrode material is required for the non-light-receiving surface side bus bar electrode 18, but there is also a disadvantage that the back electrode 18 can use only a lateral connection.
[0032]
In addition, this invention is not limited to the said embodiment, Many corrections and changes can be added to the said embodiment within the scope of the present invention. For example, the solar cell element is not limited to a crystalline solar cell such as single crystal or polycrystalline silicon, but can be applied to a thin-film solar cell element or the like as long as it is a solar cell module in which a plurality of solar cell elements are connected from a connection tab. Is done.
[0033]
【The invention's effect】
As described above, according to the solar cell element according to the present invention, the non-light-receiving surface side bus bar electrode is provided in a direction perpendicular to the light-receiving surface side bus bar electrode, so that the horizontal wiring is performed outside the array of the solar cell elements. Without being able to connect the solar cell elements, the solar cell module can be downsized. As a result, the power generation efficiency is improved, and members such as glass, filler, back material, and frame necessary for the solar cell module can be reduced or reduced, resulting in an inexpensive solar cell module and further reducing its weight. . In addition, the appearance of the solar cell module can be improved.
[0034]
Further, according to the solar cell module of the present invention, the adjacent solar cell elements are connected to each other by the connection tab between the light receiving surface side bus bar electrode and the non-light receiving surface side bus bar electrode provided in the vertical direction. Wiring can be eliminated and the solar cell module can be miniaturized. As a result, the power generation efficiency can be improved, and members such as glass, filler, back material, and frame necessary for the solar cell module can be reduced or reduced, resulting in an inexpensive solar cell module and further its weight can be reduced. Moreover, the appearance of the solar cell module can be improved by eliminating the horizontal wiring.
[Brief description of the drawings]
FIG. 1 is a view showing a solar cell module according to the present invention.
2 is a diagram showing a connection state on the surface side of two adjacent solar cell elements in the upper part of FIG. 1. FIG.
3 is a diagram showing a connection state on the back surface side of two adjacent solar cell elements in the upper part of FIG. 1. FIG.
FIG. 4 is a diagram showing another embodiment of the solar cell element of the present invention.
FIG. 5 is a diagram showing a connection state of a conventional solar cell element.
FIG. 6 is a diagram showing a conventional solar cell module.
FIG. 7 is a diagram illustrating a connection state of end portions of a conventional solar cell module.
[Explanation of symbols]
1, 2, 8, 13, 17: Solar cell element, 3, 4, 16: Front side bus bar electrode, 15, 18: Non-light receiving side bus bar electrode, 5, 6, 9, 14, 19: Connection tab, 7 : Non-light-receiving surface side finger electrode, 10: horizontal wiring, 11: connection tab connected to the surface of the solar cell element, 12: connection tab connected to the back surface of the solar cell element

Claims (2)

A solar cell element provided with a light receiving surface side bus bar electrode and a non light receiving surface side bus bar electrode electrically connected to the connection tab on the light receiving surface and the non-light receiving surface,
The solar cell element, wherein the non-light-receiving surface side bus bar electrode is provided in a direction parallel to and perpendicular to the light-receiving surface side bus bar electrode. A solar cell module having a module part comprising a plurality of solar cell elements according to claim 1 ,
The one solar cell element at the corner of the module part and the other solar cell element adjacent to the one solar cell element are the light-receiving surface side bus bar electrode of the one solar cell element and the one solar cell element. The solar cell module which connects the said non-light-receiving surface side bus-bar electrode of the said other solar cell element provided in the parallel direction with the said light-receiving-surface side bus-bar electrode of a solar cell element with a connection tab.

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