JP2012004182A - Connection method and apparatus for solar battery connecting member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance connection quality in a connection step of a solar battery connecting member for electrically connecting plural solar cells.SOLUTION: A method of connecting a connection member 52 to electrodes 54a of plural solar battery cells 51 when the solar battery cells 51 are electrically connected to one another comprises a step of positioning and mounting the connection member 52 onto the electrodes 54A of the solar battery cells 51, a step of pressing the connection member 52 against the electrodes 54A by a pair of roller electrodes 1, 1, a step of rolling the pair of roller electrodes 1, 1 in contact with the connection member 52, and a step of supplying current between the pair of roller electrodes 1, 1 through the connection member 52 while the roller electrodes are rolled in contact with the connection member 52.

Description

  The present invention relates to a method and apparatus for connecting a connection member used when electrically connecting a plurality of solar cells to electrodes of the solar cells.

  In recent years, solar cells utilizing solar energy have attracted attention and various developments have been made from the viewpoint of environmental protection. In general, a solar cell is a solar cell in which a plurality of solar cells that convert solar energy into electric energy are electrically connected by a connecting member to form a string, and the string is laminated with a transparent cover glass or a protective material. Used as a module.

This connecting member is generally called a string ribbon or interconnector, which is made of copper foil with a thickness of 0.1 to 0.2 mm, and is formed into a ribbon shape with a width of around 2 mm, and the surface is coated with solder. ing. Solar cells have electrodes on the light receiving surface and the back surface, respectively, and are generally formed of silver paste. As shown in FIG. 6 (a), the connecting member 52 is connected so that the positive and negative electrodes of the adjacent solar cells 51 and 51 are electrically connected, and is connected in series as shown in FIG. 6 (b). String 53 is formed.

  Here, as a method of soldering the connection member to the solar battery cell, as described in Patent Document 1, a method of melting the solder by pressing a heated metal from above the connection member, described in Patent Document 2 A method in which hot air is blown from above the connecting member to melt the solder, as described in Patent Document 3, a method in which the solder is melted by using a combination of heat radiation and hot air by an infrared lamp, and Recently, a method of melting solder by irradiating a connection member with laser light is known.

JP 2003-298095 A (page 3, FIG. 2) Japanese Patent Laying-Open No. 2006-332264 (page 7, FIG. 3) Japanese Patent Laying-Open No. 2004-253475 (page 7, FIG. 10)

  However, in the heated metal, the predetermined range (relatively wide range) must be contacted with a strong pressing force so that heat conduction is uniformly performed from the heated metal to the connection member with respect to the predetermined range. In addition, since heat is conducted from the heated metal to the connecting member in contact therewith, and further, heat must be conducted to the solder layer interposed between the connecting member and the solar cell electrode, the heating time (contact time) ) Must be lengthened. Therefore, heat spreads also around the electrode of the solar battery cell, and the occurrence of cracks due to the bias of external force and the temperature of the solar battery cell is a problem.

  In addition, the method by the radiation of heat and the blowing of hot air also heats the region other than the electrode of the solar battery cell, so that it has the problem of generation of cracks as described above, and due to the characteristic deterioration of the solar battery cell itself, There is also a problem that the conversion efficiency is lowered. Further, in the method of irradiating the connection member with laser light, if there is uneven reflectance on the surface (laser light irradiation surface) of the connection member, uneven absorption of the laser light energy is caused, and heating is uniform. There is a problem of not being done. This problem becomes apparent especially when the connecting member is coated with solder.

Further, the above heating method except for the heating method using laser light simultaneously heats the portion to be connected of the connection member, so that the entire connection member having a larger coefficient of thermal expansion than the solar cell is heated and expanded. Then, after the solder is solidified, it returns to room temperature while shrinking, so that stress is generated between the solar battery cell and the connection member, and remains. As a result, warpage in the direction in which the connecting member is inward is generated, and in the process after the solar battery string is formed, for example, in the stacking process for forming the solar battery module, the solar battery cell is cracked or cracked.

Therefore, in order to solve the problems as described above, the present invention allows the entire connection portion of the connection member to be soldered without unevenness without excessively heating the region other than the electrode of the solar battery cell. The purpose is to improve the connection quality.

The present invention, as a first aspect, is a method of connecting a connection member to an electrode of a solar battery cell when electrically connecting a plurality of solar battery cells, wherein the connection member is disposed on the electrode of the solar battery cell. A step of aligning and placing, a step of pressing the connection member in the direction of the electrode with a pair of roller electrodes, a step of rolling the pair of roller electrodes to the connection member, and at least during this rolling contact And a step of energizing between the pair of roller electrodes via the connection member. A method for connecting a solar cell connection member is provided.

As a result, only the contact area in the small area of the pair of roller electrodes is heated, and this heating point moves on the connection member, so that the entire connection member is not heated and thermally expanded, and the solar cell after connection The amount of cell warpage can be reduced.

According to a second aspect of the present invention, a solder layer is formed so as to be interposed between the electrode of the solar battery cell and the connection member, and resistance heating generated in the connection member by the energization is caused by the solder of the solder layer. The connection method of the connection member for solar cells as described in the first aspect is provided.

Thereby, the resistance heat generation by the Joule heat of the connection member itself becomes a heat source. Therefore, since the connection member becomes a heat source, the surrounding region that does not require heating is heated as compared with the conventional technique in which the connection member rises in temperature due to heat conduction from an external solid or gas or radiation heat from infrared rays. Without this, the solder that is in direct contact with the connecting member can be heated.

Moreover, this invention provides the connection method of the connection member for solar cells as a 3rd aspect, The said electricity supply is performed intermittently as described in any one of the 1st or 2nd aspect.

As a result, it is possible to control heating by instantaneous energization and heating pause time, and it becomes possible to control the influence of heat to the outside more precisely while maintaining connection quality.

  According to a fourth aspect of the present invention, the energization is started after the rolling contact of the pair of roller electrodes with respect to the connecting member is started, and the energization is stopped before the rolling contact is stopped. The connection method of the connection member for solar cells as described in any one of the 1st thru | or 3rd aspect to perform is provided.

  As a result, when heating by energization is performed, the pair of roller electrodes can always be in rolling contact with the connection member, so that the surface of the connection member that contacts the roller electrode is coated with solder. Even if it does, a roller electrode and a connection member do not adhere. Therefore, when soldering is completed and the roller electrode is retracted from the connection member, there is no problem that the connection member is peeled off from the electrode of the solar cell. However, the start and stop of energization in this case does not mean the start and stop of intermittent energization described as the third aspect, but the start of energization in the connection process of one connecting member. And stop.

Moreover, this invention provides the connection method of the connection member for solar cells as described in any one of the 1st thru | or 4th aspect characterized by switching the polarity of this electric current as said 5th aspect during the said electricity supply.

As a result, the polarity effect due to the direction of the current (the difference in the heat generation of the connecting members in the vicinity of both electrodes) can be reduced, so that the connection reliability is further improved.

Moreover, this invention is a connection apparatus which connects a connection member to the electrode of a photovoltaic cell, when electrically connecting a several photovoltaic cell as a 6th aspect, Comprising: The said connection member is mounted on an electrode. In addition, a mounting surface on which the solar cells are aligned and mounted, a pair of roller electrodes provided so as to be close to and separated from the connection member, and a predetermined pressing force for the pair of roller electrodes to the connection member A pressing means for contacting with each other, a drive unit for changing a relative position between the pair of roller electrodes and the connecting member in a rolling direction of the roller electrodes, and a power source for applying a voltage to the pair of roller electrodes And a rotation axis of each of the pair of roller electrodes is substantially coincident, and a direction in which the roller electrodes are in rolling contact with each other is substantially coincident with a longitudinal direction of the connection member. Connected device.

Thereby, the high quality connection of the electrode of a photovoltaic cell and a connection member is realizable.

According to a seventh aspect of the present invention, there is provided the solar cell connection according to the sixth aspect, wherein the pressing means is provided independently for each of the pair of roller electrodes. A member connection device is provided.

  As a result, even if there is a slight unevenness on the surface of the connecting member that contacts the pair of roller electrodes, both electrodes move independently to follow this unevenness, so a uniform pressing force is applied to the connecting member. Can be maintained.

Furthermore, the present invention provides, as an eighth aspect, the solar cell connection member connecting device according to any one of the sixth and seventh aspects, wherein the material of the pair of roller electrodes is tungsten. .

By using tungsten, which is a material that repels solder with poor solder wettability, as a material for the roller electrode, the possibility of adhesion between the connection member and the roller electrode is further reduced, and the yield of the connection process is improved.

As described above, the conventional heating method is a method of applying heat to the connection member from the outside of the connection member. However, according to the present invention, the connection member itself can generate heat by electric means. Therefore, it is possible to reduce the heating that is not necessary for the connection between the electrode of the solar battery and the connection member, and to reduce the adverse effect of the heat on the solar battery cell. Further, since the pair of roller electrodes are connected while always applying a pressing force to the connection point, a good connection without floating can be obtained. Furthermore, since heating is performed by energization, it is easy to control the amount of heat in a short time, and connection with stable quality is possible.

The perspective view of the to-be-connected component which shows embodiment of this invention The principal part perspective view which shows embodiment of this invention The principal part side view which shows embodiment of this invention The perspective view which shows embodiment of this invention Partial sectional view showing an embodiment of the present invention Side view and perspective view showing conventional technology

Next, embodiments of a connecting method and connecting device for a solar cell connecting member according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view illustrating the light receiving surface of the solar battery cell 51 as desired. As shown in FIG. 1A, a current collecting electrode 54B and a surface electrode 54A formed by firing a silver paste are disposed on the light receiving surface, and are aligned and connected on the surface electrode 54A. A member 52 is placed. FIG. 1B shows a state in which the connection member 52 is placed on the surface electrode 54A, and a portion where the one end of the connection member 52 protrudes from the solar battery cell 51 (symbol A) is adjacent (not shown). Connected to the back electrode of the solar cell. Here, in order to perform accurate alignment between the surface electrode 54A and the connection member 52, in recent years, the current collection electrode 54B is image-recognized and alignment is performed.

When the connection member 52 is thus positioned and placed on the surface electrode 54A that is the electrode of the solar battery cell 51, the pair of roller electrodes 1 and 1 are connected to each other as shown in FIG. Then, the connection member 52 is pressed in the direction of the surface electrode 54A with a predetermined pressing force. Here, the connection process of one of the two connection members 52 will be described with reference to the drawings. Thereafter, as shown in FIG. 2B, the placement surface (not shown) on which the solar cells 51 are placed is moved in the direction of arrow A while the connection member 52 is pressed with a predetermined pressing force.

In this way, the pair of roller electrodes 1 and 1 rolls in contact with the longitudinal direction of the connection member 52 while rotating in the direction of the arrow c. Then, after the rolling contact is started, a current is supplied from a power source (not shown) between the electrodes of the pair of roller electrodes 1 and 1. A welding power source is used as the power source in this case, but a power source capable of supplying a large current instantaneously and capable of fine output current adjustment is preferable, and a power source of a polarity switching system is still more preferable. In this embodiment, electricity is intermittently supplied every few milliseconds, and the polarity of the current is alternately switched.

FIG. 3 is a view of a state in which the pair of roller electrodes 1 and 1 are in rolling contact with the connecting member 52 from the direction of the arrow D marked in FIG. 2B, and FIG. 3 (b) is an enlarged view of a portion indicated by reference character O in FIG. 3 (a). In FIG. 3 (b), the pair of roller electrodes 1 and 1 are rotatably held with a gap indicated by reference numeral. In the present embodiment, the width of the connecting member 52 is 2 mm, whereas the gap is 0.8 mm. In addition, what is indicated by a dotted double-ended arrow key is a current flow path, which flows from one roller electrode 1 to the other roller electrode 1 via a connecting member 52. A part of the current flows through the solder layer 55 and the surface electrode 54A interposed between the surface electrode 54A and the connection member 52, but the connection member 52 is made of copper having a small electric resistance and has the shortest distance. Most of the current flows through the flow path, causing the connection member 52 to generate resistance heat.

In this way, the heat generated by the Joule heat of the connecting member 52 melts the solder of the solder layer 55 provided in contact with the connecting member 52, and soldering is performed. At this time, the heat generating portion is spot-like, and the heat generating spot moves, so that soldering can be achieved in a state where there is little adverse effect due to heat on the solar cell. In addition, since the pressed portion is spot-like, soldering can be performed with a small pressing force compared to pressing a large area heated metal, so even a thin solar cell will not be damaged. .

Next, based on FIG. 4 and FIG. 5, the connecting device for a solar cell connecting member according to the present invention will be described in detail. FIG. 4 is a schematic diagram showing the overall configuration of the connection device used in the present embodiment. Here, only the structure necessary for connecting one of the two connecting members 52 is shown, and the description will proceed. In FIG. 4, reference numeral 2 is a connection device, and 3 is a power source. Reference numeral 4 denotes a gate-type arm erected from a base (not shown), 5 denotes an elevating part held by the gate-type arm 4 so as to be movable up and down, and 6 and 6 are movable up and down independently of the elevating part 5, respectively. A pair of held electrode holders, 7 and 7 are weights for adjusting the pressing force applied to the connection member 52 by the pair of roller electrodes 1 and 1, and 8 and 8 are a pair of electrodes fixed to the electrode holders 6 and 6, respectively. Insulation blocks 9 and 9 are power supply blocks fixed to the insulation blocks 8 and 8, respectively, and 1 and 1 are a pair of roller electrodes rotatably held by the power supply blocks 9 and 9, respectively.

The roller electrodes 1 and 1 held by the power supply blocks 9 and 9 move up and down integrally with the electrode holders 6 and 6 while being electrically insulated from the electrode holders 6 and 6 through the insulating blocks 8 and 8. It is. The elevating unit 5 can be moved up and down with respect to the gate-type arm 4 by driving the first actuator 5 </ b> A, and the pair of roller electrodes 1 and 1 are moved toward or away from the connection member 52 by moving up and down. As described above, the connecting member 52 is positioned and placed on the surface electrode 54 </ b> A of the solar battery cell 51, and the solar battery cell 51 is placed on the transport belt 10 so as to be positioned. The conveyor belt 10 is intermittently moved in the direction of the arrow by the driving of the second actuator 10A which is a driving unit. Here, the moving direction of the arrow mark coincides with the longitudinal direction of the connecting member 52 and the rolling direction of the roller electrodes 1, 1.

Next, a rotatable holding structure for the pair of roller electrodes 1 and 1 will be described with reference to FIG. FIG. 5 shows a symmetric roller electrode holding structure. The right side of the figure is shown in a cross-sectional view and will be described with reference numerals attached to the right side. The roller electrode 1 is fixed to one end of a conductive shaft 11, and the conductive shaft 11 is inserted into a through hole provided in the power supply block 9. Further, conductive grease is filled between the inner surface of the through hole and the conductive shaft 11 and is held rotatably while ensuring the conductivity of both. Here, the small diameter portion 11A of the conductive shaft 11 is a grease reservoir for conductive grease.

4 is connected to the power supply blocks 9 and 9, when energized, a voltage is applied between the roller electrodes 1 and 1 via the conductive shafts 11 and 11. Further, as shown in FIG. 5, both roller electrodes 1 and 1 are arranged in a direction facing each other with a gap indicated by a reference numeral, and are provided so that their rotational axes coincide with each other. The outer peripheral surface 1 </ b> A of the maximum outer diameter portion is in contact with the connecting member 52.

Next, the operation of the connection device 2 shown in FIG. 4 will be described. After the solar cells are aligned and placed on the conveyor belt 10, a control unit (not shown) starts operation. The controller moves the conveyor belt 10 in the direction of the arrow and positions it at a predetermined position, that is, a position where the rolling contact start position on the connecting member 52 is directly below the pair of roller electrodes 1, 1. Next, when the elevating part 5 is lowered, the pair of roller electrodes 1 and 1 are also lowered, and the outer peripheral surface 1 </ b> A of the roller electrodes 1 and 1 comes into contact with the upper surface of the connection member 52. Thereafter, the elevating part 5 continues to descend, but the electrode holders 6 and 6 integrated with the roller electrodes 1 and 1 stop descending.

As a result, the relative position of the elevating unit 5 and the electrode holders 6 and 6 changes in the vertical direction, and the roller electrodes 1 and 1 are connected to each other by a predetermined pressing force, that is, the pressing force adjusted by the weights 7 and 7. 52 is pressed. Here, since the electrode holders 6 and 6 are configured to freely move up and down independently with respect to the elevating unit 5, the vertical positions of the two electrode holders 1 and 1 contact each other. Even when there is a difference, an equal pressing force is applied to these two locations. Further, the relative positions of the roller electrodes 1 and 1 and the connecting member 52 are changed, and the roller electrode is rotating, in other words, in the state where the roller electrodes 1 and 1 are in contact with the connecting member 52. Even if some unevenness exists on the surface of the member 52, the unevenness can be absorbed by the independent vertical movement of the electrode holders 6 and 6, and a predetermined pressing force can be maintained. Here, a configuration that includes the electrode holders 6 and 6 and the weights 7 and 7 and moves up and down integrally with the pair of roller electrodes and applies a predetermined pressing force to the connecting member 52 can be interpreted as pressing means. it can.

Next, the control unit controls the movement of the conveyor belt 10 and the output current of the power source 3. First, the conveyor belt 10 is moved in the direction of the arrow at a predetermined speed, and then a current is output from the power source 3. Although the details of the current have been described above, they are omitted here, but the pair of roller electrodes 1 and 1 are energized while rolling on the connecting member 52 in the longitudinal direction, and the power is supplied from the power source 3 slightly before the end of the rolling contact. Stop. When the pair of roller electrodes rolls to the rolling contact end point in a state where the energization is stopped, the control unit stops the movement of the conveyance bell and 10. At this time, since the pair of roller electrodes 1 and 1 are in rolling contact with each other while energization is performed, the upper surface of the connection member 52 and the roller electrode do not adhere to each other, and thereafter the pair of roller electrodes 1 , 1 is raised and retracted from the connection member 52, the connection member 52 is not peeled off from the solar battery cell 51. Furthermore, by making the material of the pair of roller electrodes 1 and 1 tungsten, it becomes difficult for the solder to get wet, and the possibility of adhesion between the roller electrode 1 and the connection member 52 decreases.

In the description of the present embodiment, in order to change the relative positions of the pair of roller electrodes 1 and 1 and the connection member 52, the transport belt 10 that is a mounting surface on which the solar cells 51 are mounted is moved. However, the pair of roller electrodes 1, 1 may be moved in the longitudinal direction of the connection member 52. In the present embodiment, the predetermined pressing force by the pressing means is realized using the action of gravity, but it goes without saying that the elastic force of an elastic body such as a spring may be used.

DESCRIPTION OF SYMBOLS 1 Roller electrode 2 Connection apparatus 3 Power supply 4 Portal arm 5 Lifting part 5A 1st actuator 6 Electrode holder 7 Weight 8 Insulation block 9 Feeding block 10 Conveying belt 10A 2nd actuator 11 Conductive shaft 12 Feeding cable

Claims (8)

When electrically connecting a plurality of solar cells, a method of connecting a connection member to the electrodes of the solar cells,
A step of aligning and placing the connection member on the electrode of the solar battery cell;
Pressing the connecting member in the direction of the electrodes with a pair of roller electrodes;
Rolling the pair of roller electrodes to the connecting member;
Energizing between the pair of roller electrodes via the connecting member at least during the rolling,
The connection method of the connection member for solar cells characterized by having. The solder layer is formed so as to be interposed between the electrode of the solar battery cell and the connection member, and the resistance heat generated in the connection member by the energization melts the solder of the solder layer. The connection method of the connection member for solar cells of 1. The method of connecting solar cell connecting members according to claim 1, wherein the energization is performed intermittently. 4. The energization is started after the rolling contact of the pair of roller electrodes with respect to the connecting member is started, and the energization is stopped before the rolling contact is stopped. The connection method of the connection member for solar cells of description. The method for connecting solar cell connection members according to claim 1, wherein the polarity of the current is switched during the energization. When electrically connecting a plurality of solar cells, a connection device for connecting a connection member to the electrodes of the solar cells,
A mounting surface for positioning and mounting the solar cell on which the connection member is mounted on an electrode;
A pair of roller electrodes provided so as to be close to and away from the connection member;
Pressing means for bringing the pair of roller electrodes into contact with the connecting member with a predetermined pressing force;
A drive unit that changes the relative position of the pair of roller electrodes and the connecting member in the direction of rolling contact of the roller electrodes;
A power source for applying a voltage to the pair of roller electrodes,
The rotating shaft of each of the pair of roller electrodes is substantially coincident, and the direction in which these roller electrodes roll is substantially coincident with the longitudinal direction of the connecting member. The said pressing means is provided independently with respect to each electrode of a pair of said roller electrode, The connection apparatus of the connection member for solar cells of Claim 6 characterized by the above-mentioned. The connecting device for a solar cell connecting member according to claim 6, wherein a material of the pair of roller electrodes is tungsten.

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