TWI419340B - Method of connecting solar cell components - Google Patents

Description

Solar cell component connection method

The present invention relates to a method of connecting a plurality of solar cell elements in series or in parallel to form a solar cell. More specifically, it relates to a connection method in which the use of extremely thin solar cell elements can also reduce breakage or warpage of the element to improve yield, and can provide a cheap solar cell panel.

In the solar cell, there is a power generation system that converts sunlight, which is an endless source of energy without environmental pollution, into an electric energy source. The use and scope of use of the solar cell are rapidly expanding from the residential area to the life of computers, watches, toys, and the like. .

A solar cell is a process of forming a module by electrically connecting a plurality of solar cell elements by a lead through a manufacturing process of a solar cell element, and laminating the module between a transparent outer casing material and a protective material. And made it. In addition, among various types of solar cells, in particular, amorphous germanium solar cells and polycrystalline germanium solar cells are suitable for large-area manufacturing and are inexpensive to manufacture, and have been studied in recent years. There has been considerable progress in the development of production technologies for group formation and systemization, and it has progressed from a small-sized household power generation device of about 3 kW to a large-scale power generation device of several hundred KW.

On the other hand, based on this background, as market demand increases, there is also a market demand that significantly reduces costs. One of the means to meet this demand is to thin the thickness of the component substrate constituting the solar cell from the current 300 to 500 μm. It is about 200μm. In addition, in the near future, there is even the possibility of thinning to a thinner 150 μm.

The solar cell module forming the power generating device is formed by connecting a plurality of solar cell elements in series or in parallel. The general connection method for soldering the component is to bond the surface-side collector electrode of one component to the pre-weld surface of the other component to the back side electrode of the other component. After the leads are attached to the solder, they are connected by heating, welding, and cooling the leads. However, the portion to be welded at this time is processed in one part of the lead, mainly because the difference in thermal expansion rate between the element substrate and the lead causes the substrate to be subjected to thermal stress (stress), which may cause cracking or occurrence of the element substrate depending on the situation. Warping, reducing yield. Further, as the thickness of the substrate is thinner, the above tendency tends to occur, and the resolution of these problems is urgently required.

In order to meet the above needs, for example, a solar cell module is proposed in the literature, which is disposed between a translucent surface material and a back material, and is formed by encapsulating a plurality of solar cell elements electrically connected by a joint (lead). The joint includes a connection portion that forms a mutually separated solar cell element connection surface, and a connection portion that connects the plurality of connection portions to each other (not on the solar cell element connection surface) (see, for example, Patent Document 1).

In addition, there is a document which proposes another solar cell module in which a plurality of solar cell elements (back surface electrodes are provided on the back surface and surface electrodes and collector electrodes are provided on the surface) are arranged side by side in order to connect a solar cell element to an adjacent one. Other solar cell elements are connected in series, and are provided with strip connectors for connecting the collector electrodes of a solar cell element to the back electrodes of adjacent solar cell elements; on the joints, solderable are alternately arranged along the long direction. Each of the weldable area and the non-weldable non-weldable area is plural (for example, refer to Patent Document 2).

Patent Document 1: Japanese Laid-Open Patent Publication No. H11-312820 (Patent Document 2): JP-A-2002-280591

However, the joint of Patent Document 1 includes a plurality of joint portions which are separated from each other and have a flat surface (to form a solar cell element connection surface), and a joint portion for connecting the plurality of joint portions (not connected to the solar cell element) On the surface), since the connection surface area is reduced, the component damage caused by the difference in thermal expansion rate between the joint and the solar cell element can be avoided, but the heating and cooling of the joint are simultaneously heating all the joints, and at the same time, all the joints When cooling is performed, it is inevitable that the element is broken or warped due to thermal stress, so that the processing and pressurization of each of the modular processes may cause breakage and a problem of a decrease in yield.

Further, the joint is not a commercially available right-angled lead covered with solder, but a special structure lead for bending a plurality of joint portions interposed between the joint portions, so that the bent portion is not broken or maintained The strength of this portion must be formed with high precision, and as a result, the cost has to be greatly increased.

Further, the technique described in Patent Document 2 is an improvement of the technique described in Patent Document 1. The joint of the connecting portion and the connecting portion of Patent Document 1 is replaced by a joint having a plurality of weldable regions and a plurality of non-weldable regions along the longitudinal direction, thereby preventing thermal stress on the substrate to prevent damage of the substrate. .

In other words, in the joint of the invention of Patent Document 2, the plurality of thin-plate-shaped copper fingers of the substrate are covered with a plurality of solder regions to be attached, and the surface treatment is performed with a heat-resistant resin or chrome plating which does not adhere to the solder. The mask is removed and pre-welded, so that the joint surface used is limited to the pre-welding, the joint area can be simply reduced, and the mechanical strength is not reduced. In addition, for the solar cell element, the joints are connected in an intermittent manner, which can reduce the thermal stress on the substrate during soldering and suppress damage of the substrate.

However, according to the technique described in Patent Document 2, heating and cooling of the joint are performed simultaneously with the entire length of the joint, and problems such as breakage or warpage are inevitably caused. Moreover, the joints to be used are special joints of various processes such as masks or other surface treatments at the time of production, and it is inevitable that the cost is increased.

The present invention is directed to solving the problems of the prior art described above, and the object thereof is to provide a method for connecting a low-cost solar cell component, which can be used without using the current high-priced special connector. The right-angled soldering lead of the standard product allows the solar cell element to no longer undergo unwanted thermal stress, prevents cracking or warpage of the solar cell component, and improves the yield of the solar cell component.

In order to achieve the above object, the content of claim 1 of the present invention is a method for connecting solar cell elements, characterized in that a solar cell (having a surface electrode and a collector electrode on its surface and a back electrode on its back surface) is provided by a lead wire When soldering is used to form an electrical connection, a unit operation (which consists of heating to melt the solder and cooling the molten solder) is repeatedly performed on the lead, thereby forming a continuous or intermittent connection.

The content of claim 2 of the present invention is the method of connecting solar cell elements of claim 1, wherein the heating system uses an infrared lamp, a heating gas or a welding torch.

The content of claim 3 of the present invention is the method of connecting solar cell elements of claim 1, wherein the cooling system uses a gas, a liquid or a solid.

The content of claim 4 of the present invention is the method of connecting the solar cell elements of claim 1, wherein the gas system is air.

The content of claim 5 of the present invention is the liquid system ethanol in the method of connecting solar cell elements of claim 1.

According to the invention of claim 6, in the method for connecting solar cell elements of claim 1, the nozzles are disposed on the lead at appropriate intervals, and after the nozzles are sequentially supplied with the heating gas, the cooling gas is sequentially supplied or discharged. cold.

The content of the seventh aspect of the present invention is the method of connecting the solar cell elements of claim 1, wherein a plurality of heating nozzles and cooling nozzles are disposed on the lead wires, and the heating gas is supplied from the heating nozzles and the cooling gas is supplied from the cooling nozzles. The nozzles are moved along the lead.

According to the invention of claim 8, in the method of connecting solar cell elements of claim 1, the welding torch and the cooling nozzle are disposed on the lead, and the welding torch is heated and the cooling gas is supplied to the cooling nozzle to make the welding torch And the cooling nozzle moves along the lead.

According to the invention of claim 9, in the method of connecting solar cell elements of claim 1, the heating nozzle is disposed on the lead, and the heating gas is supplied to the lead by the heating nozzle.

According to the invention of claim 10, in the method of connecting solar cell elements of claim 1, the welding torch is disposed on the lead, and the soldering torch is heated to move along the lead.

A method of connecting solar cell elements according to claim 11 of the present invention, characterized in that, when a solar cell (having a surface electrode and a collector electrode on its surface and a back electrode on its back surface) is electrically connected by wire bonding, heating is performed. After the lead melts the solder, it is repeatedly subjected to a cooling operation for solidifying the molten solder and moving it along the lead, thereby forming a continuous or intermittent connection.

When the solar cell module is formed, when the surface collector electrode of one solar cell element and the back electrode of another adjacent solar cell component are electrically connected by the soldering of the lead wire, the lead wire is repeatedly heated and The cooling unit is operated and moved, whereby the fusion connection is performed, which prevents unnecessary thermal stress from occurring in the element and prevents the element from being broken or warped, thereby greatly improving the yield.

In addition, after the solder is heated to melt the solder, the cooling operation for solidifying the molten solder is repeated and moved on the lead, thereby forming a continuous or intermittent connection, although the effect is slightly lower than the above method, the same effect can be obtained. .

The reason why the above effects can be attained by the present invention is that the heating or cooling of the entire length of the lead wire is prevented at the same time as in the prior art, and the cooling and welding operation is rapidly performed after the solder is melted, and as a result, the lead wire is just expanded by heating. The portion is immediately cooled to be contracted, so that the balance of the local expansion and contraction is maintained, and this state is continuously or intermittently formed over the entire length of the lead. Therefore, even if the lead is cooled to room temperature, the thermal stress will be suppressed or moderated, and the crack or warpage thereof will be reduced.

Further, the lead wire used in the present invention can be a right-angled soldering lead of a commercially available parity standard, and a substantial cost reduction can be achieved.

According to a feature of the present invention, a surface electrode and a collector electrode are provided on a surface of the element substrate (which is orthogonal to the surface electrode), and a back electrode is provided on the back surface of the substrate to constitute a solar cell element, and a collector electrode of one of the adjacent elements is provided. When the solar cell module is formed by soldering the leads on the other side of the electrode, the heating and cooling are not performed simultaneously on the entire length of the lead, but the unit operation is repeated on the lead (heating by melting the solder and solidifying the molten solder) Cooling and moving it, thereby forming a continuous or intermittent connection.

Further, in the technical feature of the present invention, when the solar cell element (having a surface electrode and a collector electrode on its surface and a back surface electrode on its back surface) is electrically connected by soldering of a lead, the lead is heated to melt the solder, and the solder is repeatedly applied. A cooling operation to cure the molten solder is performed and moved over the leads, thereby forming a continuous or intermittent connection.

The lead used in the present invention may be a commonly used one, for example, a standard having a right angle, a width of 1.5 mm, a thickness of 0.16 mm, and a solder on both sides of the electroplated copper.

Regarding the heating means of the present invention, such as an infrared lamp, a heating gas or a welding torch, etc. The cooling means of the present invention may be a solid such as a gas such as air, a liquid such as water or ethanol, or a copper rod having good heat conductivity. Further, the leads may be continuously welded or intermittently (spot welded) welded. In the case of intermittent welding, for example, in the case of a lead having a length of about 125 mm to 155 mm, it is usually welded at 3 to 16 places.

The connection method of the present invention is preferably carried out by an automatic device, however, the connection of the lead wires to a piece of solar cell elements is carried out by a semi-automatic device, and the solar cell elements (usually 8 to 12 pieces) are mutually The connection can also be done manually.

According to the present invention, when the lead is heated to melt the solder, and the cooling operation for curing the molten solder is repeated and moved on the lead, the total length of the lead can be connected (in the case of intermittent connection, only the point of fusion) It can be heated once or sequentially. Then, the cooling operation is continuously or intermittently repeated on the aforementioned lead wires to move them to form continuous or intermittent fusion.

In addition, in the case where the heating or cooling operation is continuously or intermittently repeated on the lead wire, the starting point is usually reversed from one end of the lead wire to the other end and moved to the working surface. It is preferable, but it is not necessarily limited to this, and any point on the lead can be used as a starting point.

Hereinafter, a preferred embodiment of the method for connecting solar cell elements of the present invention will be described. Prior to this, a solar cell module in which a plurality of solar cell elements are connected will be described with reference to FIGS. 1(a), (b), and 2; group.

In the solar cell element 1, the surface electrode 3 is formed on the surface of the substrate 2 having a thickness of 125 cm and the surface of the substrate 2 having a thickness of 200 μm, and the back surface electrode 4 is formed on the back surface thereof, and on the same surface side as the surface electrode 3, the solar cell element 1 is formed in Fig. 1 (a) and (b). Further, 2 to 3 columns (usually 2 columns) are formed with the collector electrodes 5 connected to the surface electrodes 3 for collecting electricity.

Furthermore, as shown in FIG. 2, the solar cell module 6 has the collector electrode 5 of one of the adjacent solar cell elements 1 and the other back electrode 4 along the longitudinal direction of the collector electrode 5 as the lead 7 connection. In Fig. 2, only the connection state of two components is shown, but generally 8 to 12 slices are sequentially connected in series.

Implementation aspect 1

Embodiments of the present invention will now be described with reference to FIG. Further, in Fig. 3, in order to save the trouble of the drawing, only the outline of the element 1 and the position of the collector electrode are displayed, and the surface electrode or the like is omitted. Further, in the nozzle of the device described below, only one of the two rows of collector electrodes is displayed, and the other side is omitted for explanation. The following implementations are also the same.

As shown in FIG. 3, after the solar cell element 1 (having the surface electrode 3 and the collector electrode 5 and having the back electrode 4 on the back surface) as shown in FIG. 1 is disposed on a conveyor belt (not shown) of the apparatus, Lead wires 7 are disposed on the upper portion of the elongated collector electrodes 5 forming the two rows. Next, in order to maintain the relative positional relationship between the collector electrode 5 and the lead 7, the finger portion 8A of the crimping mechanism portion 8 is extended in a direction orthogonal to the lead 7 (collector electrode 5), and is pressed from above. The lead 7 is temporarily fixed.

Thereafter, on the lead wires 7, from the one end of the lead 7 to the other end, the heating gas (heated air) is sequentially sprayed and heated from the one end of the lead 7 to the other end to melt the solder, and then the solder is melted. , sequentially switching to cooling gas (cooling air) to solidify the molten solder, thereby performing continuous or intermittent connection; or heating the heated gas (heated air) until the solder is melted, starting at one end of the lead 7 The cooling gas (cooling air) is spray-cooled from the nozzles 9 to the leads 7 in order to solidify the solder, and the lead wires 7 and the collector electrodes 5 are fused. Next, the finger portion 8A of the lead 7 is temporarily pressed back from the upper side to retreat, and a series of connection operations are completed.

The nozzle 9 is formed by concentrating and melting the solder on the lower side of the lead 7 covered with solder at its tip end. Further, after the heating gas is supplied, it may be cooled (it may be brought into contact with the atmosphere and naturally cooled) instead of the supply of the cooling gas. Further, it is also possible to heat or cool the lead by using the nozzles arranged in two rows as the heating column and the cooling column, respectively. In addition, in FIG. 3, only the nozzle is shown, and the supply pipe and the supply source which connect this nozzle to supply a heating gas or a cooling gas are abbreviate|omitted.

Implementation mode 2

As shown in Fig. 4, in the present embodiment, the solar cell element 1 is disposed on a conveyor belt (not shown) of the apparatus, and the lead wires 7 are disposed on the upper portion of the collector electrode 5, and the fingers of the crimping mechanism portion 8 are provided. The portion 8A is extended and the lead wire 7 is temporarily pressed from above to be fixed, and the like is the same as in the first embodiment.

In the present embodiment, the lead wire 7 is provided with a set of heating nozzles 10 for supplying heated air and a group of cooling nozzles 11 for supplying cooling air. Further, one set of the heating nozzles 10 and the cooling nozzles 11 that are disposed on the lead wires 7 and connected to the moving unit (not shown) of the apparatus are supplied with heated air and cooling air to the leads 7 between the adjacent finger portions 8A. .

First, the solder coated on the lead 7 is melted by the heated air from the heating nozzle 10, and then the molten solder is cooled and solidified by the cooling air from the cooling nozzle 11. A group of heating nozzles 10 and cooling nozzles 11 are treated as one unit, sequentially moved along the leads 7, and the leads 7 and the collector electrodes 5 are sequentially welded. Next, the finger portion 8A which temporarily presses the lead 7 above the lead 7 is retracted, and a series of connection operations are completed.

Implementation mode 3

As shown in Fig. 5, the present embodiment is the same as the embodiment 2 except that the heating nozzle 10 of the second embodiment is used in place of the welding torch 12.

In other words, the lead wire 7 is provided with a set of welding torch 12 and a cooling nozzle 11 for supplying cooling air. The solder coated on the lead wire 7 is first melted by the welding torch 12, and then melted by the cooling gas from the cooling nozzle 11. The solder is cooled and solidified to make a connection.

Further, in order to maintain the position of the lead 7 disposed on the collector electrode 5, the number of the finger portions 8A of the crimping mechanism portion 8 of the apparatus is set to six on one side in the first embodiment and the second embodiment, as shown in the figure. As shown in Fig. 5, the number of the fingers 8A may be two sides on one side to press the two ends of the element 1 at two positions. As described above, by reducing the number of the fingers 8A, it is easy to change the pitch between the solders, and it is easy to perform the welding continuously.

Implementation mode 4

In the present embodiment, except for the case where the cooling nozzle 11 of the above-described embodiment 3 is removed and only the welding torch 12 is provided, the same applies to the third embodiment.

In other words, the welding torch 12 is placed on the lead wire 7 so as to be sequentially moved along the lead wire 7 to be connected, and the cooling after being pressed and welded by the welding torch 12 is performed by air cooling.

[Examples]

Hereinafter, the examples are described in detail to illustrate the invention, but the invention is of course not limited to the examples.

Example 1

The solar cell elements are connected by a connection method as shown in FIG. The solar cell element 1 is a single crystal substrate having a size of 125 mm x 125 mm and a thickness of 200 μm, and the electrode is used to complete the pre-weld, and the lead is a product coated with a lead-free solder having a thickness of 160 μm and a width of 1.5 mm. Further, the wiring connection method of the element 1 is performed on the front surface and the back surface in a tandem manner. The conditions were a heated air temperature of 510 ° C, a wire connection speed of 3 seconds for a 125 mm lead length. The cooling air was subjected to a heating and cooling operation at a room temperature of 30 ° C in a mode in which the heating start point of the nozzle 10 was delayed by 0.5 second. After the preheating of the heating starting point for 0.5 seconds, the walking of the nozzle unit is started.

As a result of the above method connection, the number of pieces of the corresponding element 96 is connected, and the number of element breaks is zero. In addition, the warpage of the element, which takes the maximum measured value near the center, is 0.6 mm on average, and there is no modular processing process or damage during processing.

Comparative example 1

The connection of the leads was carried out in the same manner as in Example 1 except that the entire length of the leads was simultaneously heated and then cooled simultaneously with the entire length of the leads. Corresponding to the 96-element lead connection, there are two pieces of the element broken, and the warpage of the element is 1.8 mm on average, and one piece of damage is caused by the modular processing process or processing.

Example 2

The solar cell elements are connected by a connection method as shown in FIG. That is, the same solar cell elements and leads as in the above-described first embodiment were used, and the front and back surfaces of the solar cell elements and the leads were connected in series. This condition is that the torch temperature is 300 ° C and the lead connection speed is 5 seconds. The warm-up time for the heating start point was 0.5 seconds. Further, the cooling conditions were carried out under the same conditions as in the case of Example 1. Further, the tip end portion of the welding torch is in contact with the surface of the lead, and a titanium coating material of SU-S304 is used.

As a result of the connection by the above method, among the 96 elements of the connection lead, the damage was 0. In addition, the maximum value of the warpage of the substrate near the center was 0.5 mm, and there was no damage at the time of the modular processing or operation.

As described above, the connection method provided by the present invention can greatly reduce the damage of the components due to thermal stress during wire bonding, and reduce the warpage of the components to which the leads are connected to avoid the modular processing or operation. Causes damage and greatly increases yield.

In addition, the connection method of the present invention does not require the use of special leads, and the usual lead wires can be used to provide an inexpensive solar cell module in combination with the above-mentioned improvement in yield.

1. . . Solar cell component

2. . . Substrate

3. . . Surface electrode

4. . . Back electrode

5. . . Collecting electrode

6. . . Solar battery module

7. . . lead

8. . . Pressure line mechanism

8A. . . Finger

9. . . nozzle

10. . . Heating nozzle

11. . . Cooling nozzle

12. . . Welding torch

Fig. 1(a) is a plan view of a solar cell element, and Fig. 1(b) is a side view of the element.

2 is a side view showing a state in which a plurality of solar cell elements are connected to constitute a solar cell module.

Figure 3 is a perspective view of an embodiment of the present invention.

Figure 4 is a perspective view of another embodiment of the present invention.

Figure 5 is a perspective view of another embodiment of the present invention.

Figure 6 is a perspective view of another embodiment of the present invention.

1. . . Solar cell component

7. . . lead

8. . . Pressure line mechanism

8A. . . Finger

9. . . nozzle

Claims (8)

A method for connecting solar cell elements, characterized in that when a solar cell (having a surface electrode and a collector electrode on its surface and a back electrode on its back surface) is electrically connected by soldering of a lead, it moves over the lead The unit is operated in a unit close to the heating method and the cooling method, and the solder is partially melted, and then partially solidified rapidly, thereby forming a continuous or intermittent connection over the entire length of the lead. The method of connecting solar cell elements according to claim 1, wherein the heating system uses an infrared lamp, a heating gas or a welding torch. A method of joining solar cell elements according to claim 1, wherein the cooling system uses a gas, a liquid or a solid. A method of connecting solar cell elements according to claim 3, wherein the gas system is air. A method of connecting solar cell elements according to claim 3, wherein the liquid system is ethanol. The method of connecting solar cell elements according to claim 1, wherein the nozzles are disposed at appropriate intervals on the lead wires, and the heating gas is sequentially supplied to the nozzles, and then the cooling gas is sequentially supplied. According to the method for connecting solar cell elements according to the first aspect of the patent application, a set of heating nozzles and cooling nozzles are disposed on the lead wires, and the heating gas is supplied from the heating nozzles and the cooling gas is supplied from the cooling nozzles, and the heating nozzles and the cooling nozzles are provided. Move along the lead. The method for connecting solar cell components according to claim 1, wherein the welding torch and the cooling nozzle are disposed on the lead wire, and the welding torch is used Heating is performed and the cooling gas is supplied by the cooling nozzle, and the welding torch and the cooling nozzle are moved along the lead.