JP2005191200A - Inner lead for connecting solar cell elements, solar cell module, and method for manufacturing solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell module that suppresses voids generated in a soldered portion between a solar cell element connecting inner lead and a solar cell element while maintaining the output characteristics of the solar cell module.
SOLUTION: A strip-like inner lead 10 for connecting solar cell elements, which is provided to connect electrodes of two adjacent solar cell elements by soldering and a solder layer 7 is coated on a metal foil 11. The surface of the metal foil 11 facing the electrode has a substantially convex shape.
[Selection] Figure 1

Description

  The present invention relates to an inner lead for connecting solar cell elements, and also relates to a solar cell module in which a plurality of solar cell elements are electrically connected by the inner lead for connecting solar cell elements, and further to the solar cell module. It is related with the manufacturing method.

  A sectional view of a conventional solar cell element is shown in FIG. In FIG. 3, 13 is a semiconductor substrate, 2 is a diffusion layer, 3 is an antireflection film, 4 is a BSF layer, 5 is a front electrode, 6 is a back electrode, and 7 is a solder layer.

  As shown in FIG. 3, the solar cell element 1 is formed of a P-type region and an N-type region. A surface electrode 5 is provided on the surface of the N-type region, and a back electrode is provided on the surface of the P-type region. 6 is provided.

  The electrode formed on the surface of the solar cell element is generally obtained by applying and baking an electrode material on the front and back surfaces of the semiconductor substrate 12 by screen printing.

  FIG. 4 is a view for explaining the surface structure of a general solar cell element.

  As shown in FIG. 4, the surface electrode 5 is formed of a bus bar electrode 8 as an inner lead connection electrode for solar cell element connection and a finger electrode 9 as a current collecting electrode.

  The solar cell element connecting inner lead here is for electrically connecting the solar cell elements. Usually, a copper foil having a thickness of about 0.1 mm and a width of about 2 mm is solder-coated on the entire surface. Cut into length and soldered onto the electrode of the solar cell element. For example, when the solar cell element connecting inner leads are connected in series, the light receiving surface side electrodes and the back surface side electrodes of the adjacent solar cell elements are alternately connected.

  Although FIG. 3 shows a view in which the back electrode 6 is uniformly formed on the entire back surface, the back electrode 6 may also be composed of a connecting bus bar electrode and a collecting electrode of the inner lead for connecting solar cell elements. Solder layers 7 are formed on the front and back bus bar electrodes 8 in order to increase the cross-sectional area and reduce resistance loss and to ensure long-term reliability and to facilitate the connection of a plurality of solar cell elements. To do. Further, in order to connect the solar cell elements 1 to each other, the solar cell element connecting inner leads 10 are connected.

  FIG. 5 is a diagram showing a cross section of a solar cell element connecting inner lead used in a conventional solar cell module, FIG. 6 is a cross sectional view for explaining a wiring state of a general solar cell module, and FIG. It is a top view when it sees from the surface for demonstrating the wiring state of a solar cell module.

  The solar cell element connecting inner lead 10 has a configuration in which a solder layer 7 is formed around a rectangular copper foil 15 as shown in a schematic diagram of FIG. As shown in FIGS. 6 and 7, one end is wired over almost the entire length of the surface electrode 5, and the plurality of places are welded to the surface electrode 5, whereby the bus bar electrode 8 and the solar cell element connecting inner lead 10 are connected. Connecting. The other end is welded to the bus bar electrode 8 of the back electrode 6 of the adjacent solar cell element 1 so that the solar cell elements 1 are connected to each other. By repeating this, a solar cell module is formed.

  In order to connect the solar cell element 1 and the inner lead 10 for connecting the solar cell element, a method is generally used in which both solders are heated and soldered with a soldering iron or hot air. At this time, it is possible to heat and crimp both separately, but the solar cell element connecting inner lead 10 is wired on the electrode of the solar cell element 1 and heated from above to melt the solder of both. Crimping is more efficient in terms of productivity.

The inner lead 10 for connecting the solar cell element can be welded over the entire length of the bus bar electrode 8 of the solar cell element 1. However, due to the heat applied at the time of welding, the solar cell element 1 is warped due to the difference in thermal shrinkage between the solar cell element 1 and the inner lead 10 for connecting the solar cell element, causing cracks. Further, the bus bar electrode 8 of the solar cell element 1 may be peeled off from the end. Therefore, a method of welding to the solar cell element connecting inner leads 10 at a plurality of locations on the bus bar electrode 8 of the solar cell element 1 is frequently used (for example, see Patent Document 1). According to this method, stress is absorbed to some extent at the unwelded portion, the warpage of the solar cell element 1 can be alleviated, and cracking can be suppressed.
JP 2002-359388 A

  However, in this conventional solar cell module, all stress due to the difference in thermal shrinkage between the solar cell element 1 and the solar cell element connecting inner lead 10 is applied to the welded portion.

  FIG. 8 is a cross-sectional view of a bus bar electrode formed on the surface of a semiconductor substrate of a general solar cell element, and FIG. 9 is a state when an inner lead for connecting a solar cell element is wired on the electrode in a conventional solar cell module. It is sectional drawing for demonstrating.

  The cross section in the state where the bus bar electrode 8 and the solder formed on the surface of the semiconductor substrate 13 of the solar cell element 1 on which the electrode is formed by applying and baking the electrode material is covered is high at the center as shown in FIG. It has a shape that becomes lower as it goes. Here, in order to connect the solar cell element connecting inner lead 10 having a plate-like copper foil 15 at the center as shown in FIG. When heat is applied from above the solar cell element connecting inner lead 10 with hot air or soldering iron in the state where the battery element connecting inner lead 10 is disposed, the solder layer 7 of the solar cell element connecting inner lead 10 is externally attached. The melting starts from the outside, and the welding starts from the outside so as to flow into the surface electrode 5 from the outside and proceeds toward the inside. When the solder of the solar cell element connecting inner lead 10 flows onto the surface electrode 5 from the outside and starts welding, the welded portion takes air into the inside, and as shown in FIG. It will be in a state having 12). And once the void 12 is taken in, even if heat is applied later, the void 12 is lost and does not go outside. When the void 12 is present, the solder at that portion becomes weak, and there may be a problem that the solder cracks.

  In addition, since the solar cell module is usually used outdoors for a long time, the temperature is higher than the ambient temperature during the day, and the temperature is lower than the ambient temperature during the night. It is also affected by seasonal changes. The thermal expansion and contraction of the solar cell element connecting inner lead 10 are repeated by this temperature cycle, so that a large stress is applied to the welded portion, cracking and peeling progress, and the surface electrode 5 and the inner lead for connecting the solar cell element. 10 may be peeled off, the characteristics of the solar cell module may deteriorate, or the resistance may become extremely high in some cases, and heat may be generated to melt the filler (not shown) of the solar cell module. there were.

  In order to suppress the generation of the void 12 in the solder welded portion between the surface electrode 5 and the solar cell element connecting inner lead 10, the width of the solar cell element connecting inner lead 10 may be made smaller than the width of the surface electrode 5. Since the resistance loss of the solar cell element connecting inner lead 10 increases, the solar cell element connecting inner lead 10 must be thickened to increase the cross-sectional area.

  However, when the solar cell element connecting inner lead 10 is thickened, the solar cell element connecting inner lead 10 is heated with hot air or the like, and when it is welded to the surface electrode 5, heat is applied to the solder layer 7 of the surface electrode 5. It is difficult to transmit, and it takes time to weld the surface electrode 5 and the solar cell element connecting inner lead 10, and there is a problem that the elongation due to the thermal expansion of the solar cell element connecting inner lead 10 is further increased. When the inner lead 10 for connecting solar cell elements is welded to the surface electrode 5 in a stretched state, a larger compressive stress is applied to the welded portion when the inner lead 10 for connecting solar cell elements contracts. is there.

  Further, as another method for suppressing the generation of the void 12 in the solder welded portion, the thickness of the copper foil 15 may be reduced so as to easily follow the shape of the surface electrode 5. However, in this method, the resistance loss of the solar cell element connecting inner lead 10 becomes large, and thus the width of the solar cell element connecting inner lead 10 must be increased to increase the cross-sectional area. If it does in this way, many more voids 12 will generate | occur | produce or will become the big void 12. FIG.

  The object of the present invention has been made in view of the problems of such a conventional solar cell module, and the inner lead for connecting the solar cell element is connected to the electrode of the solar cell element while maintaining the output characteristics of the solar cell module. An object of the present invention is to provide a solar cell module that suppresses the generation of voids in the portion connected to the soldering member.

  Another object of the present invention is to provide a highly reliable solar cell module in which a plurality of solar cell elements are electrically connected using the inner lead for connecting solar cell elements, and a method for manufacturing the same.

  In order to achieve the above object, the solar cell element connecting inner lead of the present invention covers a metal foil provided with a solder layer to connect to the electrodes of two adjacent solar cell elements by soldering. A strip-shaped inner lead for connecting a solar cell element, wherein a surface portion of the metal foil facing the electrode has a substantially convex shape.

  Further, another solar cell element connecting inner lead of the present invention is a strip-shaped metal foil provided to be connected to the electrodes of two adjacent solar cell elements by soldering. An inner lead for connecting a solar cell element, wherein a surface portion of the metal foil facing the electrode of one solar cell element and the other surface portion of the metal foil on the same side as the surface portion have a substantially convex shape. Features.

  In addition, another solar cell element connecting inner lead of the present invention is characterized in that a portion of the metal foil facing the electrode is curved in a substantially convex shape in a direction toward the electrode.

  Further, the other inner lead for connecting solar cell elements of the present invention is such that the portion of the metal foil facing the electrode of one solar cell element is curved in a substantially convex shape in the direction toward the electrode, The other portion is curved in a substantially convex shape in the direction.

  Moreover, the center part of the width direction of the said metal foil may be thicker than the edge part.

  Moreover, it is desirable that the metal foil is made of copper.

  Furthermore, the solar cell module of the present invention is characterized in that a plurality of solar cell elements are electrically connected using the solar cell element connecting inner lead according to any one of claims 1 to 6.

  In the method for manufacturing a solar cell module of the present invention, the metal foil is used to cover the electrodes of two adjacent solar cell elements using a strip-shaped solar cell element connecting inner lead formed by coating a metal foil with a solder layer. A method of manufacturing a solar cell module for soldering and connecting by melting a solder layer, wherein the solder layer covering the metal foil has a substantially convex surface portion facing the electrode. To do.

  Furthermore, in another method for manufacturing a solar cell module of the present invention, the electrodes of two adjacent solar cell elements are connected to the metal foil using a strip-shaped inner lead for connecting solar cell elements formed by coating a metal foil with a solder layer. A method of manufacturing a solar cell module for soldering and connecting by melting a solder layer coated on a surface of the solder layer covering the metal foil, the surface portion facing the electrode of one solar cell element, and the surface portion The other surface portion of the metal foil on the same side has a substantially convex shape.

  According to the inner lead for connecting solar cell elements of the present invention, a strip-like solar cell formed by covering a metal foil with a solder layer provided for connecting electrodes of two adjacent solar cell elements by soldering It is an inner lead for element connection, and the surface part facing the electrode of the metal foil has a substantially convex shape, so that when the pressure is applied from the outside of the inner lead for solar cell element connection, the electrode of the convex part is applied to the metal foil. The convex metal foil contacts the electrode earliest and welding starts from this portion. If heating and pressurization are continued thereafter, welding proceeds from the inside to the outside, so that air remains in the center of the welded portion and voids are not generated as in the prior art.

  According to another solar cell element connecting inner lead of the present invention, a strip-shaped metal foil provided to connect electrodes of two adjacent solar cell elements by soldering is covered with a solder layer. An inner lead for connecting a solar cell element, wherein the surface portion of the metal foil facing the electrode of one solar cell element and the other surface portion of the metal foil on the same side as the surface portion have a substantially convex shape. The solar cell element connecting inner leads can be easily made, and the manufacturing cost can be reduced.

  In addition, if the inner lead according to the present invention is used on the light receiving surface electrode side of the solar cell element, the same contact area as before can be secured even if the electrode is made thinner than before, and the contact resistance can be increased. Therefore, the light receiving area of the solar cell element can be increased, and a high-performance solar cell module can be obtained.

  Furthermore, even if the solar cell element connecting inner lead 10 according to the present invention is used on the back surface side of the solar cell element, the same contact area as before can be ensured even if the electrode is made thinner than the conventional one. Therefore, the amount of electrode material used can be reduced and the manufacturing cost of the solar cell module can be reduced. In addition, even if the conventional electrode width is used as it is, it is possible to secure a wider contact area than before, so it is possible to reduce the pressure of crimping, and cracking of the solar cell element during the production of the solar cell module Can be suppressed.

  Further, since the metal foil is made of copper, the inner lead for connecting the solar cell element has good conductivity and is easy to solder.

  Further, the inner lead for connecting a solar cell element of the present invention is a module in which the thickness of solder on the bus bar electrode is increased in order to improve the characteristics of the solar cell element, or the inner lead for connecting solar cell element to reduce resistance loss. When used in a solar cell module having a larger cross-sectional area of the inner copper foil, particularly a thicker one, the effect is particularly effectively exhibited.

  Moreover, according to the solar cell module of the present invention, a plurality of solar cell elements are electrically connected using the solar cell element connecting inner lead according to any one of claims 1 to 5, so that the solar cell element Generation of voids at the portion where the connecting inner lead is soldered to the electrode of the solar cell element can be suppressed, and a more reliable solar cell module can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 3 shows a cross-sectional view of a solar cell element according to the present invention. Moreover, FIG. 2 is sectional drawing for demonstrating a state when the inner lead for solar cell element connection is wired on the electrode among the solar cell modules concerning this invention.

  2 and 3, 13 is a semiconductor substrate, 2 is an n-type diffusion layer, 3 is an antireflection film, 4 is a BSF layer, 5 is a front electrode, 6 is a back electrode, 7 is a solder layer, 8 is a bus bar electrode, 9 is a finger electrode, 10 is an inner lead for connecting a solar cell element, and 11 is a metal foil.

  In the present invention, the basic structure of the solar cell element is the same as the conventional one. Here, a case where a P-type silicon substrate is used as the semiconductor substrate 13 will be described as an example.

The semiconductor substrate 13 is made of single crystal silicon or polycrystalline silicon having a thickness of about 0.3 mm. This semiconductor substrate 1 contains about 1 × 10 ¹⁶ to 10 ¹⁸ atoms · cm ⁻³ of one conductivity type semiconductor impurity such as boron (B) and has a specific resistance of about 1 to 5 Ω · cm.

By placing this semiconductor substrate 13 in a diffusion furnace and heating it using phosphorus oxychloride (POCl ₃ ) or the like, phosphorus atoms are introduced into the surface portion of the semiconductor substrate 11 by 1 × 10 ¹⁶ to 10 ¹⁸ atoms · cm ^−3. The diffusion layer 2 having a thickness of about 0.3 to 0.4 μm is formed by diffusing to a certain extent.

Next, the antireflection film 3 is formed on the surface side of the semiconductor substrate 13. The antireflection film 3 is made of, for example, a silicon nitride film (SiN _x ) or the like, and has a thickness of 500 to 1000 nm and a refractive index of 1 by a plasma CVD method using a mixed gas of silane (SiH ₄ ) and ammonia (NH ₃ ). .90 to 2.30 or so. The antireflection film 3 is provided to prevent light from being reflected from the surface of the semiconductor substrate 13 and to effectively take light into the semiconductor substrate 13.

  Next, a BSF layer 4 is formed on the back surface by applying and baking an aluminum paste, and the aluminum remaining on the surface is removed. Thereafter, a silver paste is applied to the front and back surfaces of the semiconductor substrate 1 by a screen printing method or the like and baked at 600 to 800 ° C. for about 1 to 30 minutes, whereby the front electrodes 5 and the back electrodes 6 including the finger electrodes 9 and the bus bar electrodes 8 are formed. Form.

  The structure of the back surface of the solar cell element 1 may be configured by an output extraction electrode (bus bar electrode) made of silver and a current collecting electrode made of aluminum in addition to the structure shown in FIG. In this structure, the BSF layer can be formed simultaneously with the formation of the collecting electrode.

  On the surface of the front electrode 5 and the back electrode 6, in order to increase the area of the electrode and reduce the resistance, and to protect the surface of the electrode and ensure long-term reliability, wiring characteristics when connecting a plurality of elements are further provided. For the purpose of improving, the solder layer 7 is formed. The solder layer 7 is formed by immersing the solar cell element 1 in molten solder.

  Thereafter, as shown in FIGS. 6 and 7, one end of the solar cell element connecting inner lead 10 is wired over almost the entire length on the surface electrode 5, and a plurality of locations are welded to the surface electrode 5, whereby the bus bar electrode 8 and The solar cell element connecting inner lead 10 is connected. The other end is welded to the bus bar electrode 8 of the back electrode 6 of the adjacent solar cell element 1 so that the solar cell elements 1 are connected to each other. By repeating this, a solar cell module is formed.

  In order to connect the solar cell element 1 and the inner lead 10 for connecting the solar cell element, a method is generally used in which both solders are heated and soldered with a soldering iron or hot air. At this time, it is possible to heat and crimp both separately, but the solar cell element connecting inner leads 10 are wired on the surface electrode 5 formed on the surface of the semiconductor substrate 13 of the solar cell element 1, It is more efficient in terms of productivity to heat and heat the solder to melt and melt the solder.

  The inner lead 10 for connecting the solar cell element can be welded over the entire length of the bus bar electrode 8 of the solar cell element 1. However, due to the heat applied at the time of welding, the solar cell element 1 is warped due to the difference in thermal shrinkage between the solar cell element 1 and the inner lead 10 for connecting the solar cell element, causing cracks. Further, the bus bar electrode 8 of the solar cell element 1 may be peeled off from the end. Therefore, a method of welding with the solar cell element connecting inner leads 10 at a plurality of locations on the bus bar electrode 8 of the solar cell element 1 is frequently used. According to this method, the stress is absorbed to some extent at the unwelded portion, the warpage of the solar cell element 1 can be alleviated, and cracking can be suppressed.

  A strip-shaped solar cell element connecting inner lead formed by covering a metal foil with a solder layer provided to connect electrodes of two adjacent solar cell elements by soldering, The surface portion facing the electrode has a substantially convex shape.

    FIG. 1 is a view showing an embodiment of an inner lead for connecting a solar cell element used in a solar cell module according to the present invention, and (a) is substantially in a direction toward a electrode of a solar cell element to which a metal foil is soldered. The figure which showed the cross section of the state curved in the convex shape, (b) is a center compared with the edge part of the width direction so that the surface facing the electrode of the solar cell element which solders metal foil may become a substantially convex shape. The figure which showed the cross section of the metal foil which made the part thick, (c) is a figure for demonstrating one Example of the manufacturing method of the solar cell module of this invention, and soldering the solder layer which coat | covered metal foil It is a figure which shows the cross section from which the surface part facing the electrode of a solar cell element becomes substantially convex shape. FIG. 2 shows the solder welded portion when the solar cell element connecting inner leads according to the present invention corresponding to (a), (b) and (c) of FIG. 1 are welded onto the electrodes of the solar cell elements. A cross-sectional view is shown.

  As shown in FIG. 1 (a), a solar cell connecting inner lead 10 using a metal foil 11 curved in a convex shape in the direction toward the electrode of the solar cell element to be soldered is shown in FIG. If the wiring is formed on the electrode of the element, and is thermally welded by locally heating and pressurizing from above, a solder welded portion as shown in FIG. 2A can be obtained. Since the metal foil 11 has a substantially convex shape curved in a direction toward the electrode of the solar cell element to be soldered, the metal foil 11 has a convex shape when pressed from the outside of the inner lead 10 for connecting the solar cell element. The electrode and the metal foil 11 having a convex shape come into contact with the electrode earliest, and welding starts from this portion. If heating and pressurization are continued thereafter, the welding proceeds from the inside to the outside, so that air does not remain in the center of the welding portion and the void 12 is not generated as in the conventional case. Further, the metal foil 11 shown in FIG. 1 (a) is merely bent in the direction toward the electrode of the solar cell element to which the conventional metal foil 11 is soldered, and therefore the cross-sectional area thereof is not different from the conventional one. .

  Further, when the solar cell element connecting inner lead 10 is used to connect the light receiving surface side electrode of one of the two adjacent solar cell elements and the back surface side electrode of the other solar cell element, a metal If the portion of the foil 11 facing the electrode of one solar cell element is curved in a substantially convex shape in the direction toward this electrode, and the other portion of the metal foil 11 is curved in a substantially convex shape in the above direction, While there is a certain effect of preventing voids, the metal foil 11 can be easily manufactured and the cost can be reduced.

  Furthermore, if the solar cell element connecting inner lead 10 according to the present invention is used, the contact area between the electrode of the solar cell element and the inner lead can be increased as compared with the conventional case. Therefore, especially when used for the electrode on the light receiving surface side of the solar cell element, the same contact area as the conventional one can be secured even if the electrode is made thinner than the conventional one, and the contact resistance is not increased. The light receiving area of the element can be increased, and a high-performance solar cell module can be obtained.

  Furthermore, even if the solar cell element connecting inner lead 10 according to the present invention is used on the back surface side of the solar cell element, the same contact area as before can be ensured even if the electrode is made thinner than the conventional one. Therefore, the amount of electrode material used can be reduced and the manufacturing cost of the solar cell module can be reduced. In addition, even if the conventional electrode width is used as it is, it is possible to secure a wider contact area than before, so it is possible to reduce the pressure of crimping, and cracking of the solar cell element during the production of the solar cell module Can be suppressed.

  Further, if the inner lead 10 for connecting solar cell elements according to the present invention is used, the contact area between the electrode of the solar cell element and the inner lead can be increased as compared with the prior art. Can be reduced. Therefore, it becomes possible to reduce the number of manufacturing steps of the solar cell module, reduce the number of places where local stress is applied, and increase the portion that absorbs and relaxes the stress. A more reliable solar cell module can be obtained.

  It is also possible to reduce the area of the solder weld. Therefore, it is possible to reduce the stress concentrated on the solder welded portion, to suppress the cracking of the solar cell element, and to obtain a more reliable solar cell module.

  Therefore, using the same material as the conventional solar cell element connecting inner lead, it is possible to obtain a solar cell module that suppresses the damage of the solar cell element connecting inner lead while maintaining the electric conduction characteristics of the solar cell module. .

  The metal foil is made of a highly conductive metal such as silver, copper, aluminum, or iron, but is made of copper in consideration of its conductivity, ease of handling, and material cost. Is preferred.

  In the case of using a copper foil for the solar cell element connecting inner lead, the solar cell element connecting inner lead 10 is usually formed by immersing the copper foil 11 in the solder melt, but the solar cell element used in the present invention. The connecting inner lead 10 may be formed by immersing the previously curved copper foil 11 in a solder melt, or the conventional solar cell element connecting inner lead 10 may be bent and used. . However, it is preferable that the conventional solar cell element connecting inner lead is bent and used immediately before wiring to the solar cell element because the handling is convenient and the material used is not different from the conventional one.

  FIG. 1 (b) is a view for explaining another embodiment of the solar cell element connecting inner lead of the present invention. The metal foil 11 of the solar cell element connecting inner lead 10 used in the solar cell module is shown in FIG. It is the figure which showed the cross section. As shown in FIG. 1B, the metal foil 11 having a thicker central portion than the end portion in the width direction is formed so that the surface portion facing the electrode of the solar cell element to be soldered with the metal foil 11 has a substantially convex shape. If the inner lead 10 for connecting the solar cell element used is wired on the electrode of the solar cell element as shown in FIG. 8 and thermally welded by locally heating and pressing from above, FIG. A solder weld as shown can be obtained. Since the surface portion facing the electrode of the solar cell element to which the metal foil 11 is connected has a substantially convex shape, when the pressure is applied from the outside of the inner lead for connecting the solar cell element, the convex electrode on the metal foil and the electrode The convex metal foil 11 contacts the earliest and welding starts from this portion. If heating and pressurization are continued thereafter, the welding proceeds from the inside to the outside, so that air does not remain in the center of the welding portion and the void 12 is not generated as in the conventional case.

  Further, when the solar cell element connecting inner lead 10 is used to connect the light receiving surface side electrode of one of the two adjacent solar cell elements and the back surface side electrode of the other solar cell element, a metal If the surface of the foil 11 facing the electrode of one solar cell element and the other surface of the metal foil 11 on the same side as this surface are made substantially convex, the metal foil has a certain effect of preventing voids. 11 can be easily manufactured, and the cost can be reduced.

  Therefore, it is possible to obtain a solar cell module in which damage to the inner lead for connecting the solar cell elements is suppressed while maintaining the electric conduction characteristics of the solar cell module. Moreover, according to this method, even if it presses from the outer side of the inner lead for solar cell element connection, the metal foil 11 does not bend and does not return to a plate shape, so that sufficient pressurization can be performed. Further, if the same cross-sectional area as that of the conventional one is maintained, the thickness of the metal foil 11 is increased, so that the width of the solar cell element connecting inner lead 10 can be reduced. Therefore, the light receiving area of the solar cell element can be increased. Furthermore, if the same width of the inner lead 10 for connecting solar cell elements as in the conventional case is maintained, the conductive resistance can be lowered and the characteristics of the solar cell module can be improved by increasing the thickness of the inner lead 10 for connecting solar cell elements.

  FIG. 1C is a view for explaining an embodiment of the method for manufacturing the solar cell module of the present invention, and shows a cross section of the inner lead 10 for connecting solar cell elements used in the solar cell module according to the present invention. FIG. In the method for manufacturing a solar cell module of the present invention, a solar cell module manufacturing method in which a plurality of solar cell elements are connected by thermal welding with an inner lead for solar cell element connection in which a solder layer is coated on a metal foil, The inner lead for connecting the solar cell element is characterized in that the surface portion facing the electrode of the solar cell element to be soldered of the solder layer coated with the metal foil has a substantially convex shape.

  In order to make the surface of the inner lead 10 for connecting the solar cell element facing the electrode of the solar cell element to be soldered into a substantially convex shape, as shown in FIGS. 1 (a) and 1 (b), a metal foil is used. The metal foil 11 is curved in a direction toward the electrode of the solar cell element 11 to be soldered, or the end of the surface portion facing the electrode of the solar cell element to be connected by soldering the metal foil 11 has a substantially convex shape. What is necessary is just to use the metal foil 11 which made the center part thicker than the part. However, in addition to these, a flat metal foil 11 is used as shown in FIG. 1 (c), and the surface portion of the solder layer 7 coated on the metal foil 11 facing the electrode of the solar cell element to be soldered has a substantially convex shape. There is a way to do it.

  As shown in FIG. 1C, a solar cell element connecting inner lead 10 having a substantially convex surface portion facing the electrode of the solar cell element to be soldered of the solder layer 7 coated on the metal foil 11 is shown in FIG. If wiring is carried out on the electrodes of the solar cell element as shown, and heat welding is performed by locally heating and pressurizing from above, a solder weld as shown in FIG. 2C can be obtained. Since the surface portion of the solder layer 7 covering the metal foil 11 facing the electrode of the solar cell element to be soldered has a substantially convex shape, the metal foil protrudes when pressed from the outside of the inner lead for connecting the solar cell element. The electrode having the shape and the convex solder layer 7 come into contact with the electrode earliest and welding starts from this portion. If heating and pressurization are continued thereafter, the welding proceeds from the inside to the outside, so that air does not remain in the center of the welding portion and the void 12 is not generated as in the conventional case.

  Further, when the solar cell element connecting inner lead 10 is used to connect the light receiving surface side electrode of one of the two adjacent solar cell elements and the back surface side electrode of the other solar cell element, a metal If the surface portion of the solder layer 7 covered with the foil 11 facing the electrode of one solar cell element and the other surface portion of the solder layer 7 on the same side as this surface portion are made substantially convex, a certain effect of preventing voids is achieved. However, the metal foil 11 can be easily manufactured and the cost can be reduced.

  The metal foil 11 used at this time may be the same as the conventional one. By doing in this way, the solar cell module which suppressed the failure | damage of the inner lead for solar cell element connection can be obtained, maintaining the electrical conductivity characteristic of a solar cell module. Further, according to this method, even if the pressure is applied from the outside of the inner lead for connecting the solar cell elements, only the solder melts and sinks on the lower surface of the inner lead 10 for connecting the solar cell elements, so that sufficient pressure can be applied. Become. Further, when the pressure is sufficiently applied, the thickness of the solder welded portion of the resulting solar cell module becomes the same as that of the conventional one, so that no problem occurs in the process after the wiring of the solar cell element connecting inner lead 10.

  Also in the above case, the metal foil is made of a highly conductive metal such as silver, copper, aluminum, or iron, but considering its conductivity, ease of handling, and material cost. It is preferable to be made of copper.

  In addition, in the above, although demonstrated in the case of the serial connection which connects the light reception surface side electrode of one solar cell element, and the back surface side electrode of the adjacent solar cell element, the light reception surface side of the adjacent solar cell element It goes without saying that the same effect can be obtained even in the case of parallel connection in which the electrodes or the backside electrodes are connected.

  Although the embodiment of the present invention has been described in detail above, the present invention is not limited to this. For example, it is possible to wire different solar cell element connecting inner leads on the front and back electrodes, and connect the solar cell element connecting inner leads to the back side, the front side, or between the solar cell elements. It is.

  Two bus bar electrodes are shown on the solar cell element, but may be one or three or more.

  Moreover, it is also possible to use a solar cell element whose entire surface is coated with solder without distinguishing the bus bar electrode as the back electrode of the solar cell element.

  In the above description, an electrode obtained by applying and baking an electrode material has been described as an example, but the present invention is not limited to this. For example, even if the upper end of the electrode is obtained by sputtering or vapor deposition using a photolithographic method, the solder coated on the surface of the electrode has a substantially semicircular shape because of wettability. The effect is demonstrated.

  Further, the solder type may be Sn-Pb so-called 6-4 solder or so-called lead-free solder which does not contain Pb.

  Further, the present invention effectively exhibits the effect even if the solar cell module has a structure in which a solar cell element having no solder layer on the electrode of the solar cell element is connected to the inner lead for connecting the solar cell element.

  Furthermore, the present invention can be applied to a place where the inner leads for connecting solar cell elements are connected.

FIG. 1 is a view showing an embodiment of an inner lead for connecting a solar cell element used in a solar cell module according to the present invention, and (a) is substantially in a direction toward a electrode of a solar cell element to which a metal foil is soldered. The figure which showed the cross section of the state curved in the convex shape, (b) is a center compared with the edge part of the width direction so that the surface facing the electrode of the solar cell element which solders metal foil may become a substantially convex shape. The figure which showed the cross section of the metal foil which made the part thick, (c) is a figure for demonstrating one Example of the manufacturing method of the solar cell module of this invention, and soldering the solder layer which coat | covered metal foil It is a figure which shows the cross section from which the surface part facing the electrode of a solar cell element becomes substantially convex shape. Sectional drawing of the solder welding part when the inner lead for solar cell element connection concerning the present invention corresponding to each of (a), (b), and (c) of Drawing 1 was welded on the electrode of the solar cell element was shown. Is. It is the figure which showed the cross section of the general solar cell element. It is a figure for demonstrating the surface structure of a general solar cell element. It is the figure which showed the cross section of the inner lead for a solar cell element connection used for the conventional solar cell module. It is sectional drawing for demonstrating the wiring state of a common solar cell module. It is a top view when it sees from the surface for demonstrating the wiring state of a common solar cell module. It is sectional drawing of the bus-bar electrode of a common solar cell element. It is sectional drawing for demonstrating a state when the inner lead for solar cell element connection is wired on the electrode among the conventional solar cell modules.

Explanation of symbols

1: Solar cell element 2: Diffusion layer 3: Antireflection film 4: BSF layer 5: Front electrode 6: Back electrode 7: Solder layer 8: Bus bar electrode 9: Finger electrode 10: Inner lead 11 for connecting solar cell element: Metal Foil 12: Void 13: Semiconductor substrate 14: Copper foil

Claims (9)

A strip-shaped solar cell element connecting inner lead formed by covering a metal foil with a solder layer and connected to the electrodes of two adjacent solar cell elements by soldering, An inner lead for connecting a solar cell element, wherein a surface portion facing an electrode has a substantially convex shape. A strip-shaped inner lead for connecting a solar cell element, which is provided to connect to the electrodes of two adjacent solar cell elements by soldering, and is coated with a solder layer on one of the metal foils An inner lead for connecting a solar cell element, wherein a surface portion facing the electrode of the solar cell element and the other surface portion of the metal foil on the same side as the surface portion have a substantially convex shape. The solar cell element connecting inner lead according to claim 1, wherein a portion of the metal foil facing the electrode is curved in a substantially convex shape in a direction toward the electrode. A portion of the metal foil facing the electrode of one solar cell element is curved in a substantially convex shape in a direction toward the electrode, and another portion of the metal foil is curved in a substantially convex shape in the direction. The solar cell element connecting inner lead according to claim 2, wherein: The inner lead for connecting a solar cell element according to claim 1 or 2, wherein a central portion in the width direction of the metal foil is thicker than an end portion. The inner lead for solar cell element connection according to any one of claims 1 to 5, wherein the metal foil is made of copper. A solar cell module, wherein a plurality of solar cell elements are electrically connected using the inner lead for connecting solar cell elements according to claim 1. The sun which solder-connects by melt | dissolving the solder layer which coat | covered the electrode of two adjacent solar cell elements using the strip | belt-shaped solar cell element connection inner lead which coat | covers a solder layer to metal foil, and coat | covers the electrode of two adjacent solar cell elements A method for manufacturing a battery module, wherein the solder layer covering the metal foil has a substantially convex surface portion facing the electrode. The sun which solder-connects by melt | dissolving the solder layer which coat | covered the electrode of two adjacent solar cell elements using the strip | belt-shaped solar cell element connecting inner lead which coat | covers a solder layer on metal foil, and coat | covers the electrode of two adjacent solar cell elements A method for manufacturing a battery module, wherein a surface portion of the solder layer covering the metal foil facing the electrode of one solar cell element and the other surface portion of the metal foil on the same side as the surface portion are substantially convex. The manufacturing method of the solar cell module characterized by having comprised.

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