JP2012084911A - Interconnector, solar battery string using the same, and solar battery module using such solar battery string - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an interconnector capable of reducing warpage generated in a solar battery cell after a connection thereof to a solar battery cell, and excellent in reliability after the connection as well.SOLUTION: An interconnector is provided with a strip-shaped conductive member 3 which electrically connects electrodes of adjacent solar battery cells. The conductive member is a planar type and includes a stress relief section X1, which has a notch forming a corner with an obtuse angle at its side end part or which has linear side end part. Since stress due to difference between the thermal expansion coefficient of the interconnector and that of the solar battery cell is remarkably relaxed by such constitution, warpage generated in the solar battery cell is reduced and reliability of connection between the interconnector and the solar battery cell is improved.

Description

  The present invention relates to an interconnector for connecting solar cells, a solar cell string using the interconnector, a manufacturing method thereof, and a solar cell module using the solar cell string. More specifically, the solar cells are connected by an interconnector. It is related with the interconnector which can reduce the curvature which arises in each photovoltaic cell when being done.

  In recent years, a solar cell that directly converts solar energy into electric energy has been rapidly expected as a next-generation energy source particularly from the viewpoint of global environmental problems. There are various types of solar cells, such as those using compound semiconductors or organic materials. Currently, the mainstream is the one using silicon crystals. As solar power generation systems spread rapidly, it is indispensable to reduce the manufacturing cost of solar cells, and it is very effective to increase the size and thickness of silicon wafers as substrate materials in reducing manufacturing costs. Means.

  However, with the increase in size and thickness of silicon wafers, interconnectors conventionally used (elongated conductive members for electrically connecting adjacent solar cells, see interconnector 11 in FIG. 19) and the sun When an attempt is made to produce a solar cell string (see FIG. 18) using the battery cell electrodes (see electrodes 18a and 18b in FIGS. 20 and 21) as they are, the solar cell electrodes and interconnectors are connected. In the heating step, there is a problem that the solar battery cell is greatly warped when the temperature is lowered to room temperature due to a difference in thermal expansion coefficient between silicon which is the substrate material of the solar battery cell and copper which is the base material of the interconnector. Arise.

  Further, the warpage generated in the solar battery cell causes a transport error and a cell crack in the transport system of the automated module manufacturing line. Further, in a state where a plurality of solar cells are electrically connected by an interconnector (hereinafter referred to as “string” in the present invention), if each solar cell is warped, resin sealing for module production is performed. In the process, a strong force is locally applied to each solar cell constituting the string, which causes a crack in the solar cell.

  In order to cope with such a problem, it is provided with an elongated conductive member for electrically connecting the electrodes of adjacent solar cells, and the conductive member is a connection part whose both ends are connected to the electrodes of the solar cell, An interconnector having a plurality of small cross-sectional area portions whose cross-sectional areas are locally reduced has been proposed for at least one of the connection portions (see, for example, Patent Document 1).

  If such an interconnector is used, since the interconnector has a small cross-sectional area portion in which at least one of the connection portions is arranged along the longitudinal direction of the conductive member, the small cross-sectional area is relatively weak compared to other portions. The portion is stretched by the force of returning to the original shape of the solar cell warped, and as a result, the warp generated in the solar cell is reduced (see FIGS. 22 to 26).

  Further, since the warpage of the solar battery cell is reduced by extending the small cross-sectional area as described above, the interconnector is connected to the entire surface of the solar battery electrode without worrying about the thermal stress applied to the solar battery cell. The parts can be joined, and the reliability after connection is excellent.

JP 2005-142282 A

  If the above-mentioned interconnector is used, during the manufacturing process of the solar cell module, for example, due to the heat history in the heating process for connecting the electrode of the solar battery cell and the interconnector, the interconnector can be expanded and contracted in the longitudinal direction. There has been a problem of local concentration on the locally reduced small cross-sectional area of the interconnector. Therefore, it is necessary to process a large number of small cross-sectional areas for the purpose of dispersing the stretching force, which is not preferable in terms of increasing the manufacturing cost of the interconnector itself.

  Further, the stress in the longitudinal direction of the interconnector due to the thermal cycle at the time of connecting the interconnector, the stress in the longitudinal direction of the interconnector due to the thermal cycle at the time of creating the solar cell module, for example, due to the softening flow of the sealing resin of the solar cell module When the stress is reduced locally due to the stress in the connector's longitudinal direction and the stress in the connector's longitudinal direction due to the thermal cycle after the module is installed, the stress in the same direction is concentrated locally on the small cross-sectional area. In addition, there is a possibility of disconnection of the interconnector, and there is a problem in long-term reliability.

  In addition, it is easy to handle an interconnector having an elongated conductive member that is continuously stored in a reel shape. When the interconnector is wound up or pulled out in a reel shape, the interconnector has a tension in a locally reduced small cross-sectional area. This is not preferable in that it causes concentration and damage and deformation to the interconnector leading to manufacturing defects.

  Also, sometimes notch parts of the interconnector may interfere with each other and smoothly take up or pull out in a reel-like manner. Proceeding with the setting in the cell is not very preferable in that it leads to damage and deformation of the interconnector, or to a transport error in the transport system that supplies the interconnector of the module production line.

  The present invention has been made in consideration of such circumstances, and can provide an interconnector that can reduce warpage generated in a solar battery cell after connection with the solar battery cell and is excellent in reliability after connection. With the goal.

  The interconnector of the present invention that solves the above problems includes, in one aspect, a belt-like conductive member that electrically connects the electrodes of adjacent solar cells, and the conductive member includes a stress relief portion. The stress relief portion is a planar type and has a notch so as to form an obtuse angle portion at the side end portion, or the side end portion has a linear shape.

  In one embodiment of the interconnector of the present invention, the conductive member includes a plurality of planar stress relief portions. In one embodiment of the present invention, a plurality of conductive members are continuously stored in a reel shape.

  In another aspect, the interconnector of the present invention includes a conductive member that electrically connects electrodes of adjacent solar cells, and at least a part of the conductive member is connected to the electrodes of the solar cell, and the conductive In at least another part of the member, the member has a small cross-sectional area portion punched out so that the cross-section is separated on both sides.

  In yet another aspect, the interconnector of the present invention includes a conductive member that electrically connects the electrodes of adjacent solar cells, and at least a part of the conductive member is connected to the electrodes of the solar cell, At least another part of the conductive member has a small cross-sectional area part whose cross-sectional area is continuously reduced by providing a notch part whose side part is notched.

  The cutout portion in the present invention includes at least a portion that is cut in a curved shape portion or an oblique direction with respect to the longitudinal direction of the conductive member. Moreover, in one embodiment of the present invention, the plurality of cutout portions are cut out with respect to each other in point symmetry or line symmetry.

  The solar cell string of the present invention to which the above interconnectors are applied includes solar cells each having an electrode adjacent to each other, and an interconnector that electrically connects the electrodes of the adjacent solar cells.

  The method for producing the solar cell string of the present invention includes a step of connecting the electrodes of the solar cells and the interconnector by any one of heater heating, lamp heating, and reflow.

  The solar cell module of the present invention includes a sealing material that seals the solar cell string, and a pair of external terminals that extend from the solar cell string to the outside via the sealing material.

  According to the present invention, the stress due to the difference in thermal expansion coefficient between the interconnector and the solar battery cell is remarkably relieved. As a result, the warpage generated in the solar battery cell is reduced and the connection between the interconnector and the solar battery cell is reduced. Reliability is also improved. In addition, the stress relief part is a flat type, and the side end part has a notch so as to form an obtuse angle part, or the side end part has a linear shape. It is possible to make the stress relief part of the structure less likely to get caught.

  Moreover, since the curvature of a photovoltaic cell is reduced as mentioned above, generation | occurrence | production of the conveyance error and cell crack in the conveyance system of a module preparation line are prevented. Moreover, since the cell crack in the resin sealing process for module manufacture is also prevented, the yield and productivity of a solar cell module improve.

  In addition, disconnection of the interconnector in the setting process, the heat treatment process, the resin sealing process, etc. for manufacturing the module is prevented, so that the yield and productivity of the solar cell module are improved.

An example of the shape of the small cross-sectional area part in case the cross section of a conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. An example of the shape of the small cross-sectional area part in case the cross section of a conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. An example of the shape of the small cross-sectional area part in case the cross section of a electrically-conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view, (d) is a stress relief part. FIG. An example of the shape of the small cross-sectional area part in case the cross section of a conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. An example of the shape of the small cross-sectional area part in case the cross section of a conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. An example of the shape of the small cross-sectional area part in case the cross section of a conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. An example of the shape of the small cross-sectional area part in case the cross section of a conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. An example of the shape of the small cross-sectional area part in case the cross section of a conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. An example of the shape of the small cross-sectional area part in case the cross section of a conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. An example of the shape of the small cross-sectional area part in case the cross section of a conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. An example of the shape of the small cross-sectional area part in case the cross section of a conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. An example of the shape of the small cross-sectional area part in case the cross section of a conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. An example of the shape of the small cross-sectional area part in case the cross section of a conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. An example of the shape of the small cross-sectional area part in case the cross section of a conductive member is a square is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. It is a top view of an example which shows the interconnector of this invention. The top view of an example which shows the photovoltaic cell of this invention is shown, (a) is a front view, (b) is a back view. It is explanatory drawing which shows the solar cell string by this invention. It is explanatory drawing which shows the solar cell module by this invention. It is a top view of an example which shows the conventional interconnector. The top view of an example which shows the conventional photovoltaic cell is shown, (a) is a front view, (b) is a back view. It is explanatory drawing which shows the conventional solar cell string. It is a figure which shows the photovoltaic cell connected by the conventional interconnector. It is an enlarged view of the connection part of the conventional interconnector. It is explanatory drawing which shows a mode that the conventional interconnector is joined by applying heat to the electrode of a photovoltaic cell. It is explanatory drawing which shows the state which the interconnector joined by applying the conventional heat | fever was cooled to room temperature, and the curvature occurred in the photovoltaic cell. It is explanatory drawing which shows the state by which the small cross-sectional area part of the conventional interconnector extended | stretched and the curvature of the photovoltaic cell was reduced.

  The interconnector according to the present invention is formed of a strip-shaped conductive member 3, and the conductive member 3 is preferably formed in a linear shape. More preferably, the stress relief portion is formed in a planar shape and can be arranged parallel to the surface of the solar battery cell without a gap. The conductive member 3 is provided with at least one stress relief portion that relieves stretching stress, and the interconnector stress relief portion has a structure that is not easily caught. More preferably, the stress relief location has a cross-sectional area that continuously changes along the longitudinal direction of the interconnector so that the force is not concentrated locally in the stress relief location. Alternatively, it is characterized by having a cross-sectional area where the cross section of the stress relief portion is branched so that the force does not concentrate locally in the stress relief portion.

  Furthermore, it is desirable to use an interconnector in which a notch is arranged so that the stretching stress at the stress relief location acts in an oblique direction with respect to the longitudinal direction.

  Furthermore, it is desirable to use an interconnector in which a notch is arranged so that the stretching stress at the stress relief location is dispersed.

  Furthermore, the stress relief location of the interconnector preferably corresponds to the electrode pattern of the solar cell, and it is desirable that the stress relief location is not physically connected to the electrode of the solar cell.

  Here, the solar battery cell 2 includes those formed using an elemental semiconductor such as amorphous, polycrystalline, single crystal silicon, or a compound semiconductor such as GaAs.

  The conductive member 3 is made of a conductor formed in a strip shape such as a foil shape or a plate shape, and is preferably made of a conductor formed so as to be housed in a reel shape.

  When the conductive member has a strip shape, the width W is preferably about 0.5 to 5.0 mm, more preferably about 0.5 to 3.0 mm, and particularly preferably about 2.5 mm. The thickness T is preferably about 0.05 to 0.5 mm, more preferably about 0.05 to 0.3 mm, and particularly preferably about 0.2 mm.

  One end or both ends of the conductive member may be branched into a plurality. For example, when one of adjacent solar cells has a plurality of electrodes on its light receiving surface and the other has one electrode on its back surface, an interconnector made of a conductive member with one end branched into a plurality It is preferable to use it.

  The conductive member includes various metals and alloys, and specifically includes metals such as Au, Ag, Cu, Pt, Al, Ni, and Ti, and alloys thereof, among which Cu is used. It is preferable.

  The conductive member is preferably subjected to solder plating. The interconnector to which the solder plating is applied is securely connected to the silver electrode of the solar battery cell. Solder plating may be performed after the formation of the small cross-sectional area portion or may be performed before the formation of the small cross-sectional area portion.

  Each small cross-sectional area portion 7 means a portion in which the cross-sectional area is reduced as compared with the majority of the interconnector. Specifically, it means a narrow part or a small diameter part formed by cutting out a part of the connecting part. Examples of a method for cutting out a part of the connecting portion include a method of mechanically cutting and polishing, a method of punching with a mold, and a method of performing etching.

  The small cross-sectional area portion 7 is stretched with a relatively weak force because the strength is weak against the stretching stress as compared with the majority of the interconnector. For this reason, a small cross-sectional area part extends | stretches with the restoring force which the curved photovoltaic cell returns to the original shape, and contributes to reducing the curvature of a photovoltaic cell.

  In addition, although there exists a concern about the electrical resistance of an interconnector increasing by providing a small cross-sectional area part, the length of each small cross-sectional area part along the longitudinal direction of a electrically-conductive member is very short compared with the interconnector full length. By setting the length, it is possible to suppress the increase in the electrical resistance of the entire interconnector to a level that can be ignored.

  In addition, a small cross-sectional area portion may be formed between adjacent solar cells, and when the distance between adjacent solar cells changes, the small cross-sectional area portion extends, The stress applied to the interconnector is relieved.

  A small cross-sectional area part can be made into the shape shown in FIGS. 1 to 3 show an example of a shape in which the cross section of the conductive member is square and, for example, a small cross-sectional area is formed by a pair of cutout portions formed on the opposite side surfaces of the conductive member. 4 to 11 show examples of shapes in which the conductive member has a square cross section and a small cross-sectional area is formed by a notch formed inside the interconnector. 1 to 11, (a) is a front view of the connection portion, (b) is a side view of the connection portion, and (c) is a bottom view of the connection portion.

  As shown in FIGS. 1 (a), (b), and (c), the small cross-sectional area portion 7 has two side surfaces facing the conductive member 3 in the range of S1 in the longitudinal direction of the interconnector and D1 in the short direction. 3a and 3b are cut and formed so as to be curved relative to each other, thereby providing a cross-sectional area in which the cross section of the stress relief portion X1 continuously changes along the longitudinal direction of the interconnector.

  Here, when the conductive member has a plate shape, the width W1 is about 2.5 mm, and the thickness T1 is about 0.20 mm, S1 is about 2 to 5 mm, and D1 is particularly preferably about 0.5 to 1.0 mm. The minimum width of the small cross-sectional area portion 7 is preferably about 0.5 to 1.5 mm.

  As shown in FIGS. 2A, 2B, and 2C, the small cross-sectional area 7 has two side surfaces facing the conductive member 3 in the range of S2 in the longitudinal direction of the interconnector and D2 in the short direction. 3a and 3b are cut and formed so as to bend alternately along the longitudinal direction, so that the cross section of the stress relief location X2 has a cross-sectional area that continuously changes along the longitudinal direction of the interconnector.

  Although FIG. 2 shows an example in which the notch portions do not overlap in the longitudinal direction, a part of the notch portions may overlap in the longitudinal direction.

  Here, when the conductive member is plate-shaped, the width W2 is about 2.5 mm, and the thickness T2 is about 0.20 mm, S2 is about 1 to 5 mm, and D2 is about 0.5 to 1.5 mm. The minimum width of the small cross-sectional area portion 7 is preferably about 0.5 to 1.5 mm.

  As shown in FIGS. 3A, 3B, and 3C, the small cross-sectional area 7 has two side surfaces facing the conductive member 3 in the range of S3 in the longitudinal direction of the interconnector and D3 in the short direction. 3a and 3b are cut and formed so as to bend alternately along the longitudinal direction, so that the cross section of the stress relief location X2 has a cross-sectional area that continuously changes along the longitudinal direction of the interconnector.

  Although FIG. 3 shows an example in which the notch portions do not overlap each other in the longitudinal direction, a part of each notch portion may overlap in the longitudinal direction. In FIG. 3, the shape of the notch is trapezoidal, but the corner of the notch may be curved. Moreover, the small cross-sectional area part 7 flows diagonally in the same direction with respect to the longitudinal direction by the hypotenuse of the mutual trapezoidal cutout. Further, because the angle formed by the side surface of the conductive member and the oblique side of the trapezoidal cutout portion is obtuse due to the trapezoidal cutout shape, the stress relief portion of the interconnector has a structure that is not easily caught. In other words, when winding a continuous interconnector around a reel, pulling it out from a reel, etc., or when setting the interconnector to connect to a solar cell during the module manufacturing process, interconnectors and other members Interference with can be avoided. That is, it is possible to avoid or reduce damage such as deformation or disconnection of the interconnector itself due to excessive stress on the interconnector or stress due to catching before connection to the solar battery cell.

  Here, when the conductive member is plate-shaped, the width W3 is about 2.5 mm, and the thickness T3 is about 0.20 mm, S3 is about 1 to 5 mm, and D3 is particularly preferably about 0.5 to 1.5 mm. The minimum width of the small cross-sectional area portion 7 is preferably about 0.5 to 1.5 mm.

  Further, the width WB of the small cross-sectional area defined by the opposite oblique sides of the opposing trapezoidal notch portions and the small cross-sectional area defined by the upper side of the trapezoidal notch opposed to the side surface of the band-shaped conductive member The width WA is preferably WB> WA. Thereby, it becomes easy to change the shape in the longitudinal direction of the interconnector by extending at a small cross-sectional area portion having a width WA of a plurality of locations (two locations in the present embodiment), and at a plurality of locations. It becomes possible to disperse the stretching. Further, since the interconnector of FIG. 3 is point-symmetric, it is possible to disperse the stretching efficiently.

  Note that, in any of the stress relief locations X1 to X3 of the interconnector in the embodiment shown in FIGS. 1 to 3, the corners constituted by the notches and the side end portions are obtuse. . Thereby, a stress relief location can be made into the structure which is hard to produce a catch.

  As shown in FIGS. 4A, 4B, and 4C, the small cross-sectional area portion 7 has two side surfaces facing the conductive member 3 in the range of S7 in the longitudinal direction of the interconnector and D7 in the lateral direction. 3a and 3b are formed by being cut out in a slit shape that alternately crosses the longitudinal direction along the longitudinal direction, and the opening portion of the slit-like cutout portion is rounded. Thereby, the cross section of the stress relief location X7 has a cross sectional area that continuously changes along the longitudinal direction of the interconnector. In FIG. 4, it is preferable that the slit-shaped notch end is curved, but the notch end may be rectangular or the like. Moreover, the same direction is preferable as the direction of the slit-shaped notches, and the small cross-sectional area 7 flows obliquely in the reverse direction with respect to the longitudinal direction.

  Here, when the conductive member is plate-shaped, the width W7 is about 2.5 mm, and the thickness T7 is about 0.20 mm, S7 is about 0.1 to 2 mm, and D7 is particularly preferably about 1 to 2.0 mm. The minimum width of the small cross-sectional area portion 7 is preferably about 0.5 to 1.5 mm.

As shown in FIGS. 5A, 5B, and 5C, the small cross-sectional area 7 is rectangular on the inner plane of the conductive member 3 in the range of S8 in the longitudinal direction of the interconnector and D8 in the short direction. Two cutout portions cut out in the shape are provided in the longitudinal direction, and are shifted from each other in the short direction. The interconnector is branched by providing a rectangular cutout on the inner plane of the conductive member 3, thereby providing a cross-sectional area in which the cross section of the stress relief location X8 changes in a dispersive manner. In addition, when the corner of the rectangular cutout is curved, the cross section of the stress relief location X8 also has a cross-sectional area that continuously changes along the longitudinal direction of the interconnector. FIG. 5 includes two notches cut in a rectangular shape on the inner plane of the conductive member 3 and is shifted from each other in the short direction, but there are two or more notches. It does not matter if they are not displaced from each other in the lateral direction.
If the cross-sectional area is shifted from each other in the short direction, the small cross-sectional area with a smaller cross-sectional area will be extended mainly in the longitudinal direction, but the current path is the smaller cross-sectional area with the larger cross-sectional area. Because of this, the cross-sectional area changes little by stretching and is stable, and the interconnector can efficiently collect the generated power.

  Here, when the conductive member is plate-shaped and its width W8 is about 2.5 mm and thickness T8 is about 0.20 mm, S8 is about 0.1 to 2 mm, and D8 is particularly preferably about 1 to 2.0 mm. Z8 is preferably 0 to 0.5 mm, and the minimum width of the small cross-sectional area portion 7 is preferably about 0.25 to 1.5 mm.

  As shown in FIGS. 6A, 6B, and 6C, the small cross-sectional area 7 is mounted on the inner plane of the conductive member 3 in the range of S9 in the longitudinal direction of the interconnector and D9 in the short direction. Two cutout portions cut out in the shape are provided in the longitudinal direction, and are shifted from each other in the short direction. By providing a trapezoidal notch on the inner plane of the conductive member 3, the interconnector is branched, thereby providing a cross-sectional area in which the cross section of the stress relief location X9 changes dispersively. In addition, the hypotenuse of the trapezoidal notch is inclined by about 45 degrees with respect to the longitudinal direction and is disposed opposite to each other, so that the cross section of the stress relief location X9 continuously changes along the longitudinal direction of the interconnector. It also has an area. FIG. 6 includes two notches cut in a trapezoidal shape on the inner plane of the conductive member 3 in the longitudinal direction, and the trapezoidal notches of each other are shifted from each other in the short direction, thereby reducing the length in the longitudinal direction. The cross-sectional area part 7 flows diagonally in the same direction.

  Further, as shown in FIG. 7, the hypotenuse of the trapezoidal notch is tilted by about 30 degrees with respect to the longitudinal direction, and the tilt angle may be set as appropriate.

  Further, as shown in FIG. 8, by making the lateral displacement of the trapezoidal notch portions opposite to those in FIG. 6, the small cross-sectional area 7 flows obliquely in the reverse direction with respect to the longitudinal direction. It has become.

  Moreover, as shown in FIG. 9, the number of notches may be three or more, and it does not need to be shifted from each other in the lateral direction. The corner of the trapezoidal notch is preferably curved.

  Here, when the conductive member is plate-shaped and the widths W9, W10, W11, and W12 are about 2.5 mm and the thicknesses T9, T10, T11, and T12 are about 0.20 mm, S9, S10, S11, and S12 are 0. About 1 to 3 mm, and D9, D10, D11, and D12 are particularly preferably about 1 to 2.0 mm. Z9, Z10, Z11, and Z12 are preferably 0 to 0.5 mm, and the minimum width of the small cross-sectional area portion 7 is preferably about 0.25 to 1.5 mm.

  As shown in FIGS. 10A, 10B, and 10C, the small cross-sectional area 7 is circular on the inner plane of the conductive member 3 in the range of S13 in the longitudinal direction of the interconnector and D13 in the short direction. Two cutout portions cut into the shape are provided in the longitudinal direction. By providing a circular notch on the inner plane of the conductive member 3, the interconnector is branched, thereby providing a cross-sectional area in which the cross section of the stress relief location X13 changes dispersively. In addition, the stress relief portion X13 has a cross-sectional area in which the cross section continuously changes along the longitudinal direction of the interconnector.

  10 and FIG. 11 may be arranged so as to be shifted from each other in the lateral direction, and as shown in FIG. 12, they may be arranged so as not to be shifted from each other in the lateral direction.

  Moreover, it may be oval instead of circular, and the major axis may be oblique to the longitudinal direction.

  Here, when the conductive member is plate-like and its widths W13, W14 and W15 are about 2.5 mm, and the thicknesses T13, T14 and T15 are about 0.20 mm, S13, S14 and S15 are about 1 to 3 mm, D13, D14 and D15 are particularly preferably about 1 to 2.0 mm. Z13 and Z14 are preferably 0 to 0.5 mm, and the minimum width of the small cross-sectional area portion 7 is preferably about 0.25 to 1.5 mm.

  As shown in FIGS. 13A, 13B, and 13C, the small cross-sectional area 7 is rectangular on the inner plane of the conductive member 3 in the range of S16 in the longitudinal direction of the interconnector and D16 in the short direction. It has one notch cut into the shape. The interconnector is branched by providing a rectangular cutout on the inner plane of the conductive member 3, and has a cross-sectional area in which the cross section of the stress relief location X16 changes dispersively.

  14A, 14B, and 14C, the small cross-sectional area 7 has an inner plane of the conductive member 3 in a range of S17 in the longitudinal direction of the interconnector and D17 in the lateral direction. 1 is provided with one notch cut out in a circular shape. The interconnector is branched by providing a circular notch on the inner plane of the conductive member 3, and the cross-sectional area in which the cross section of the stress relief location X16 changes dispersively and continuously along the longitudinal direction of the interconnector. Prepare.

  Moreover, it may be oval instead of circular, and the major axis may be oblique to the longitudinal direction.

  In FIG. 13, the case where the major axis of the interconnector and the center axis of the notch overlap each other has been described. However, the major axis of the interconnector and the center axis of the notch may be displaced.

  Here, when the conductive member is plate-shaped and the widths W16 and W17 are about 2.5 mm and the thicknesses T16 and T17 are about 0.20 mm, S16 and S17 are about 1 to 3 mm, and D16 and D17 are 1 to 2. About 0 mm is particularly preferable. The minimum width of the small cross-sectional area portion 7 is preferably about 0.25 to 1.25 mm.

  From another point of view, the present invention includes solar cells each having an electrode adjacent to each other, and an interconnector that electrically connects the electrodes of the adjacent solar cells, the interconnector according to the present invention described above. It also provides a solar cell string that is an interconnector.

  In the solar cell string according to the present invention, each solar cell is preferably square and each side is preferably 155 mm or more.

  In the solar cell string according to the present invention, each solar cell preferably has a thickness of 300 μm or less.

  In other words, as the solar cell becomes larger and thinner, the problem of the warpage of the solar cell becomes more prominent. However, when the above-described interconnector according to the present invention is used, the warp that occurs when the interconnector is connected. Is effectively reduced, and productivity is improved.

  From another viewpoint, the present invention is a method for manufacturing the above-described solar cell string according to the present invention, in which the electrode of the solar cell and the connection part of the interconnector are heated, heated by a lamp, And a method of manufacturing a solar cell string including a step of connecting by any one of the reflow methods.

  According to such a manufacturing method, the connection portion of the solar cell electrode and the interconnector is connected by any one of heater heating, lamp heating, and reflow methods, so that the entire surface of the solar cell electrode is covered. The interconnector is joined to increase the long-term reliability of the completed module.

  From another viewpoint, the present invention includes a solar cell string, a sealing material that seals the solar cell string, and a pair of external terminals that extend from the solar cell string to the outside through the sealing material, The solar cell string also provides a solar cell module which is the above-described solar cell string according to the present invention.

  By sealing the solar cell string with the sealing material, the environmental resistance of the solar cell string is improved. For example, an ethylene-vinyl acetate copolymer is used as the sealing material.

  The solar cell module according to the present invention may further include a surface protective layer made of glass, polycarbonate or the like on the light receiving surface side, a back film made of acrylic resin on the back surface side, and a frame made of aluminum around the periphery. good.

  The solar cell module according to the present invention can be various solar cell modules such as a roof tile integrated module, a slate roof tile integrated module, or a daylighting module.

  An interconnector according to Embodiment 1 of the present invention will be described with reference to FIGS.

  15 is a plan view showing the interconnector according to Embodiment 1 of the present invention, FIGS. 16A and 16B are explanatory views showing the electrode arrangement on the light receiving surface and the back surface of the solar battery cell, and FIG. 17 is FIG. FIG. 17 is an explanatory diagram showing a state where the interconnector shown in FIG. 16 is connected to the light receiving surface electrode and the back surface electrode of the solar battery cell.

  The interconnector 1 shown in FIG. 15 is made of, for example, a conductive member (copper wire) 3 plated with solder, has a maximum width W1 (see FIG. 1A) of 2.5 mm, and a maximum thickness T1 (FIG. 1). (See (c)) is 0.20 mm. Other materials for the conductive member may be copper / aluminum / copper or copper / indium / copper alloys.

  As shown in FIG. 15, the interconnector 1 has a plurality of small cross-sectional area portions 7. For example, as shown in FIG. 1, each small cross-sectional area portion 7 forms both side surfaces 3 a and 3 b of the conductive member 3 in the width direction. About 0.75 mm each, and are arranged along the longitudinal direction of the conductive member 3 so as to avoid both silver electrodes corresponding to the light receiving surface silver electrode and the back surface silver electrode of a predetermined solar battery cell. Yes.

  FIG. 16A is an example of the surface electrode pattern of the crystalline silicon solar battery cell of Example 1 of the present invention, and FIG. 16B is an example of the back electrode pattern of the crystalline silicon solar battery cell of Example 1 of the present invention. As shown in FIG. 16A, two spaces (non-connection portions) 10 are provided in the middle of the front electrode main grid, and the main grid is thus divided into three. Further, as shown in FIG. 16 (b), the back silver electrode / interconnector connection portion and the front silver electrode / interconnector connection portion are designed to be symmetrical on the front and back sides. FIG. 17 shows a state in which the interconnector is connected to the solar battery cell thus designed. FIG. 17 is a sectional view showing a state in which the crystalline silicon solar battery cells of Example 1 of the present invention are connected by an interconnector. The interconnector is not connected to the grid in the gap portion provided in the front electrode main grid, and the small cross-sectional area portion 7 of the interconnector is arranged in this gap portion. On the back surface, the interconnector and the solar battery cell are not soldered at the aluminum electrode portion 6 but are soldered only at the silver electrode portion. Here, the aluminum electrode is arranged in the small cross-sectional area portion 7 of the interconnector.

  In addition, as shown in FIG. 17, the connecting portion between the front interconnector and the front silver electrode and the connecting portion between the back interconnector and the back silver electrode are arranged at the same position, so that the interconnector and The stress caused by the difference in thermal expansion coefficient of the solar battery cells is almost equal between the front and back sides. Therefore, the stress caused by the thermal expansion between the cell and the interconnector, which is one cause of the warpage of the solar battery cell, is kept balanced between the front and the back. That is, the same force is applied to the solar cell from the front and back by arranging the small cross-sectional areas 7 in the portions where the silver electrodes and the interconnector are not connected with the electrode pattern as described above. Due to these effects, the warpage of the solar battery cell is reduced, and the occurrence of poor connection and cell cracking can be prevented.

A connection process between each silver electrode and the interconnector will be described.
The solar cell 9 shown in FIG. 17 is composed of a polycrystalline silicon substrate having a side of 155 mm and a thickness of 200 μm, for example. In addition, an interconnector for connecting a plurality of solar cells 9 is formed by continuously cutting a conductive member covered with solder on an elongated wiring member made of copper or the like into a reel shape and cutting it to a designed length. Used. The interconnector may have a stress relief portion formed in advance on the reel, or may be formed when the stress relief portion is cut from the reel.

  Next, as shown in FIG. 17, the interconnector 1 and the solar cells 9 provided with silver electrodes are alternately conveyed and set. That is, the back electrode 8 b of the solar battery cell 9 is overlaid on the interconnector 1, another interconnector 1 is overlaid on the light receiving surface electrode 8 a of the solar battery cell 9, and another interconnector 1 is overlaid on the interconnector 1. The back electrodes 8b of the solar cells 9 are sequentially stacked. The interconnector 1 and each silver electrode are soldered and connected by performing, for example, heating with the interconnector and solar cells arranged as much as necessary. That is, the interconnector connected to the main grid on the light receiving surface wraps around the back surface of the adjacent cell and is connected to the back surface silver electrode.

  In this way, a solar cell string 22 having a small warpage in which a plurality of solar cells 2 are electrically connected to each other by the interconnector 1 is completed.

  As described above, by using the interconnector as shown in FIGS. 1 to 4, it is possible to reduce the shrinkage stress applied to the cells during cooling in the interconnector connecting step. That is, a cross-sectional area continuously changing along the longitudinal direction of the interconnector is provided in order to avoid stress concentration and local disconnection while providing a partially weak region of the interconnector.

  In particular, by using an interconnector as shown in FIGS. 5 to 12, it is possible to reduce the shrinkage stress applied to the cells during cooling in the interconnector connection process. In other words, the interconnector has a cross-sectional area that changes in a distributed manner by branching the interconnector in order to avoid stress concentration and local disconnection while providing a partially weak region of the interconnector. The cross-sectional area continuously changing along the longitudinal direction of

  In particular, by using an interconnector as shown in FIGS. 13 and 14, it is possible to reduce the shrinkage stress applied to the cells during cooling in the interconnector connection process. That is, the interconnector has a cross-sectional area that changes in a distributed manner by branching in order to avoid a stress concentration and local disconnection while providing a partially weak region of the interconnector.

  Further, in particular, by using the interconnector as shown in FIGS. 5 to 14, the cutout portion that is caught by the shape of the interconnector when the interconnector is supplied in connection with the solar cell of the interconnector is the side surface portion of the conductive material 3. Since it does not exist in 3a and 3b, the apparatus can be easily transported and the productivity can be improved.

  Next, a solar cell module 23 using the solar cell string 11 is shown based on FIG.

If necessary, the solar cell strings 11 are connected in series by using a slightly thick wiring material called a bus bar, and the cell rows thus connected are made of EVA (ethylene vinyl acetate) as the sealing material 24. After being sandwiched by the film, it is sandwiched by a back film formed of a glass plate as the surface protective layer 25 and an acrylic resin as the back film 26. When the bubbles that have entered between the films are decompressed (laminated) and heated (cured), EVA is cured and the solar cells 2 are sealed. Thereafter, an aluminum frame, which is a frame 29, is fitted on the four sides of the glass plate, and a terminal box is connected to a pair of external terminals 27, 28 extending from the solar cell string 22 to the outside, thereby completing the solar cell module 23. .

  Thus, since the solar cell module 23 uses the solar cell string 22 with a small warp, the cell cracking of the solar cell 2 is reduced in the sealing process by the sealing material 24.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1,11,21,31 Interconnector, 2,12,20 Solar cell, 3,33 Conductive member, 3a, 3b Conductive member side surface, 6,16 Aluminum electrode, 7, 37 Small cross-sectional area, 8a, 18a Surface electrode, 8b, 18b Back electrode, 9, 19, 39 Solar cell, 22 Solar cell string, 23 Solar cell module, 24 Sealing material, 25 Surface protective layer, 26 Back film, 27, 28 External terminal, 29 Frame, 35 Connection part.

The present invention relates to an interconnector that connects solar cells , a solar cell string that uses the interconnector , and a solar cell module that uses the solar cell string , and more specifically, when solar cells are connected by an interconnector. The present invention relates to an interconnector capable of reducing warpage occurring in a solar battery cell.

The present invention has been made in consideration of such circumstances, and an interconnector that can reduce warpage generated in a solar battery cell after connection with the solar battery cell and is excellent in reliability after connection is used. An object of the present invention is to provide a solar cell string and a solar cell module using the solar cell string .

The interconnector of the present invention that solves the above problem includes a conductive member for electrically connecting the electrodes of adjacent solar cells, and the conductive member is a solar cell of one of the solar cells. At least two connection portions connected to the electrode on the same surface side of either the light receiving surface side or the back surface side thereof are provided, and the electrodes are connected between the connection portions connected to the electrodes of the one solar cell. A stress relief part is provided at a position not connected, and the stress relief part has a branch part branched by providing an opening in the conductive member, and at least one of the cross-sectional areas of the branch part is a cross-sectional area of the non-branch part. Smaller than .

In one embodiment of the interconnector of the present invention, the opening is rectangular or trapezoidal, or circular or elliptical .

In another embodiment of the interconnector of the present invention, at least one corner of the opening is curved, and the cross-sectional area continuously changes from the non-branching portion to the branching portion .

In yet another embodiment of the interconnector of the present invention , the opening is also formed between the one solar cell and the solar cell adjacent to the one solar cell .

FIG. 16A is an example of a crystalline silicon solar cell surface electrode pattern of Example 1 of the present invention, and FIG. 16B is an example of a crystalline silicon solar cell back electrode pattern of Example 1 of the present invention. As shown in FIG. 16 (a), in the middle of the light-receiving surface electrode 8a is a table electrode main grid, the gap (non-connecting portions) of the two positions the light-receiving surface electrode 8a is interrupted 10 a is provided, As a result, the main grid is divided into three. Further, as shown in FIG. 16B, the back silver electrode / interconnector connection portion and the front silver electrode / interconnector connection portion are designed to be symmetrical on the front and back sides. That is, the silver electrode 8b on the back surface is provided with a portion 10b where the silver electrode 8b is interrupted at a position on the back side corresponding to the gap 10a of the light receiving surface electrode 8a. FIG. 17 shows a state in which the interconnector is connected to the solar battery cell thus designed. FIG. 17 is a sectional view showing a state in which the crystalline silicon solar battery cells of Example 1 of the present invention are connected by an interconnector. The interconnector is not connected to the grid in the gap portion provided in the front electrode main grid, and the small cross-sectional area portion 7 of the interconnector is arranged in this gap portion. On the back surface, the interconnector and the solar battery cell are not soldered at the aluminum electrode portion 6 but are soldered only at the silver electrode portion. Here, the aluminum electrode is arranged in the small cross-sectional area portion 7 of the interconnector.

In addition, as shown in FIG. 17, the connecting portion between the front interconnector and the front silver electrode and the connecting portion between the back interconnector and the back silver electrode are arranged at the same position, so that the interconnector and The stress caused by the difference in thermal expansion coefficient of the solar battery cells is almost equal between the front and back sides. Thus, is one of the causes of warpage of the solar cell occurs, the stress caused by the thermal expansion coefficient between the cell and the interconnector, the balance is maintained in the front and back. That is, the same force is applied to the solar cell from the front and back by arranging the small cross-sectional areas 7 in the portions where the silver electrodes and the interconnector are not connected with the electrode pattern as described above. Due to these effects, the warpage of the solar battery cell is reduced, and the occurrence of poor connection and cell cracking can be prevented.

Claims (11)

A strip-shaped conductive member that electrically connects the electrodes of adjacent solar cells,
The conductive member includes a stress relief portion, and the stress relief portion is a flat type and has a notch so as to form an obtuse corner at the side end portion, or the side end portion is An interconnector that is linear.   The interconnector according to claim 1, wherein the conductive member includes a plurality of planar stress relief portions.   The interconnector according to claim 2, wherein the plurality of conductive members are continuously stored in a reel shape.   A conductive member that electrically connects electrodes of adjacent solar cells, wherein at least a part of the conductive member is connected to an electrode of the solar cell, and at least another part of the conductive member has a cross section on both sides; The interconnector in any one of Claims 1-3 which has the small cross-sectional area part punched out so that it might isolate | separate into the part side.   A conductive member that electrically connects the electrodes of adjacent solar cells, wherein at least a part of the conductive member is connected to an electrode of the solar cell, and at least another part of the conductive member, a side surface portion thereof The interconnector according to any one of claims 1 to 3, further comprising a small cross-sectional area part in which a cross-sectional area is continuously reduced by providing a notch part in which is cut out.   The interconnector according to claim 4, wherein the notch has a curved portion at least partially.   The interconnector according to claim 4 or 5, wherein the notch includes a portion that is cut in an oblique direction with respect to a longitudinal direction of the conductive member.   The interconnector according to claim 4 or 5, wherein the plurality of cutout portions are cut out in a point symmetry or a line symmetry with respect to each other.   A solar battery string comprising solar cells adjacent to each other, each having an electrode, and the interconnector according to any one of claims 1 to 7, which electrically connects the electrodes of the solar cells adjacent to each other. .   It is a method for manufacturing the solar cell string according to claim 9, comprising a step of connecting the electrode of the solar cell and the interconnector by any one of heater heating, lamp heating, and reflow method. The manufacturing method of a solar cell string.   A solar cell module comprising: the solar cell string according to claim 9; a sealing material that seals the solar cell string; and a pair of external terminals that extend from the solar cell string to the outside through the sealing material.

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