JP5100629B2 - Manufacturing method of solar cell module - Google Patents

Description

  The present invention relates to a method for manufacturing a solar cell module.

A conventional solar cell module has a plurality of solar cell elements connected in series and in parallel. The plurality of solar cell elements are electrically connected to one electrode and the other electrode of adjacent solar cell elements, with leads fixed by solder. Fixing of the lead to such a solar cell element is performed by cooling the solder after heat welding.
JP 2007-188932 A

  However, when the lead is fixed to the solar cell element, as the solder is welded and cooled, stress is applied to the solar cell element substrate due to the difference in thermal expansion coefficient between the solar cell element and the lead. There was a possibility of warping.

  The present invention has been devised in view of the above conventional problems, and an object thereof is to provide a solar cell module including a solar cell element with reduced warpage.

The method for manufacturing a solar cell element according to the present invention includes a lead, a plurality of solar cell elements including a first surface and a second surface on the back side of the first surface, the electrode having electrodes on the second surface. A step of preparing, a step of soldering the leads to the electrodes of the plurality of solar cell elements, a step of fixing the plurality of solar cell elements soldered to the leads to a plate, and fixing to the plate the lead and the cooling step of cooling the solar cell element is the the plate, meet manufacturing method of the solar cell module and a step of releasing the fixing of the said cooled the lead and the solar cell element The plate has a convex portion on a side in contact with the first surface of the solar cell element, and in the cooling step, the first surface of the solar cell element is disposed on the convex surface of the plate. Press in.

  According to the method for manufacturing a solar cell module of the present invention, after the lead and the solar cell element are melt-bonded with solder, the solar cell string is cooled in a fixed state. Is reduced. As a result, according to the present invention, cracks and warpage generated in the solar cell element can be reduced.

The solar cell module of this embodiment has a solar cell string in which a plurality of solar cell elements are connected by leads. The manufacturing process of the solar cell module according to the present embodiment includes a process of sucking and transporting a plurality of semiconductor substrates on which leads are soldered, and cooling the transported semiconductor substrates in a state of being sucked and fixed. By having such a process, the sun
The stress generated in the battery element is reduced, and a solar cell module in which cracking and warping of the solar cell element hardly occur can be manufactured.

  For example, as shown in FIG. 1A, the solar cell module 30 of the present embodiment includes, in order from the light receiving surface side, a translucent substrate 31 made of translucent glass and the like, and a translucent made of a thermosetting resin. Filler 32, solar cell string 40 whose periphery is protected by filler 32, filler 32 made of thermosetting resin, film 33 protecting the back side of solar cell module 30, and terminal for taking out the output A box 34 is provided.

  The solar cell string 20 of the solar cell module 30 of the present embodiment has a structure in which a plurality of solar cell elements 10 are electrically connected by leads 11 as shown in FIGS. 1B and 1C, for example. Have.

  Solar cell element 10 used in the present embodiment includes a light receiving surface 1a (first surface) that receives sunlight and a non-light receiving surface 1b (second surface) located on the back side thereof. As the solar cell element 10, a solar cell element in which electrodes having different polarities are provided on the light receiving surface 1a and the non-light receiving surface 1b, or a back contact type solar cell having a plurality of electrodes having different polarities on the non-light receiving surface 1b. An element structure is used. The back contact solar cell element includes a semiconductor substrate 1 having a plurality of through holes 3 penetrating a light receiving surface 1a and a non-light receiving surface 1b, and a metal in which a plurality of electrodes having different polarities are provided on the non-light receiving surface 1b It includes a solar cell element having a wrap-through (MWT) structure and an emitter wrap-through (EWT) structure, and a solar cell element having a structure having no through hole. Here, the solar cell element of the MWT structure is a solar cell element having a structure in which a metal is provided in the through-hole on the surface side of the solar cell element, and the electromotive force collected on the light receiving surface through the metal is taken out from the electrode on the non-light receiving surface side. A solar cell element having an EWT structure is a solar cell having a structure in which a diffusion layer is provided in the through-hole on the surface side of the solar cell element, and the electromotive force collected on the light receiving surface through the diffusion layer is extracted from the electrode on the non-light receiving surface side. Battery element. In particular, when a solar cell module is manufactured in the above-described process with respect to a back contact type solar cell element, the load on the solar cell element 10 and the lead 11 can be reduced, and a leakage current caused by a shift in the connection position of the lead 11 Or a short circuit can be suppressed. Furthermore, since no lead is provided on the light-receiving surface side, the entire solar cell element can be adsorbed and fixed uniformly and uniformly, so that variation in the amount of warpage in the solar cell element can be suppressed in the cooling step, The stress applied to the solar cell element can be evenly distributed throughout the element.

  Such a back contact type solar cell element 10 will be described with reference to FIGS. The semiconductor substrate 1 of the solar cell element 10 has one conductivity type. The first surface 1a and the second surface 1b of the semiconductor substrate 1 have a first reverse conductivity type layer 2a (reverse conductivity type layer 2) and a third reverse conductivity type layer 2c (reverse conductivity type layer 2). A second reverse conductivity type layer 2 b (reverse conductivity type layer 2) is provided on the inner wall of the through hole 3 of the semiconductor substrate 1.

  When a P-type silicon substrate is used as the semiconductor substrate 1 exhibiting one conductivity type, such a second reverse conductivity type layer 2b (N-type) is formed by, for example, phosphorus being diffused on the inner wall of the through hole 3. . Similarly, by diffusing phosphorus or the like, the N-type first reverse conductivity type layer 2a and the third reverse conductivity type layer 2c (reverse conductivity type layer 2) are formed on the first and second surfaces of the semiconductor substrate 1. Can be formed.

  The first bus bar electrode (non-light-receiving surface side electrode) 4c in the first electrode 4 is electrically connected to the light-receiving surface side electrode 4a through the through-hole electrode 4b in the through-hole 3 as shown in FIG. And formed on the second surface 1b of the semiconductor substrate 1 so as to block at least a part of the opening of the through-hole 3. The first bus bar electrode 4c can be formed, for example, by firing an electrode material mainly composed of silver or the like.

  The light-receiving surface side electrode 4a formed on the first surface 1a is formed so as to go around the opening of the through hole 3 on the first surface 1a. For example, as shown in FIG. Since the linear current collecting electrode is provided on the first surface, the generated carriers can be efficiently collected even on the first surface side.

  The second electrode 5 is different in polarity from the first electrode 4. For example, if the first electrode 4 is an electrode provided in the n-type region, the second electrode 5 is in the p-type region. The electrode is formed on the second surface 1 b of the semiconductor substrate 1. The second electrode 5 is formed by firing an electrode material mainly composed of aluminum or silver to form a current collecting electrode 5b, and is electrically connected to the current collecting electrode 5b and mainly composed of silver or the like. The material is fired to form the second bus bar electrode 5a. By providing the second bus bar electrode 5a, it is possible to easily position the wiring member described later. In addition, by providing the current collecting electrode 5b over substantially the entire surface other than the region where the second electrode is formed, the moving distance of the carriers collected by the second electrode 5 is shortened, and the current collected by the second electrode 5 is reduced. Since the amount of carriers that can be charged can be increased, the output characteristics of the solar cell element can be improved.

  The “bus bar electrode” here means an electrode to which the lead 11 is connected.

  The collecting electrode 5b can also have a role of increasing the photocurrent by reflecting the light that has not been absorbed in the semiconductor substrate 1 back into the semiconductor substrate 1 again. In particular, when aluminum is used as the electrode material for the current collecting electrode 5b, the heavily doped layer 6 can be formed simultaneously when the current collecting electrode 5b is formed by firing the electrode material.

  The heavily doped layer 6 is formed by diffusing boron or aluminum at a high concentration over substantially the entire surface of the second surface 1 b of the semiconductor substrate 1 other than the vicinity of the through hole 3, and the first surface of the semiconductor substrate 1. It is formed so as to be located between 1a and the second electrode 5 described above. Here, the high concentration means that the impurity concentration is higher than the concentration of one conductivity type impurity in the semiconductor substrate 1.

  In addition, a passivation film made of an amorphous silicon film containing silicon, a silicon nitride film, or the like may be formed on the second surface 1b. By opening a part of the passivation film, the first bus bar electrode 4c has a through hole. The second electrode 5 can be connected to the semiconductor substrate 1 while being connected to the electrode 4b.

  Next, an example of the shape of the electrode formed on the second surface 1b side will be described with reference to FIG.

  The first bus bar electrode 4c and the second bus bar electrode 5a are disposed on the second surface 1b side of the semiconductor substrate 1 as shown in FIG. The strip-shaped first bus bar electrode 4c is divided into a plurality of rows (three rows in FIG. 3B), and each is divided into a plurality of portions (with a gap) (see FIG. 3). 7 in 3 (b)). On the other hand, as the second bus bar electrode 5a, a rectangular one has a plurality of rows along the row of the first bus bar electrodes 4c (three rows in FIG. 3B, the number of rows is the row of the first bus bar electrodes 4c). Are divided into a plurality of pieces (with a gap) (six in FIG. 3B).

In FIG. 3B, the relationship between the first bus bar electrode 4c and the second bus bar electrode 5a is that at least partially adjacent second bus bar electrodes 5a exist for all the gaps between the first bus bar electrodes 4c. It is arranged to meet. For example, in FIG. 3B, the second bus bar electrode 5a1 is adjacent to a part of the gap s1, and the gap s2 is entirely formed.
The second bus bar electrode 5a2 is adjacent. Further, the second bus bar electrode 5a may have a single long shape without providing a plurality of each. In particular, by providing a plurality of collector electrodes and a collector electrode 5b made of a fired aluminum electrode between them, carriers can be collected efficiently and the region where the high-concentration doped layer 6 is formed can be easily enlarged. Furthermore, by providing the finger portion 5c in the gap between the first bus bar electrodes 4c, the carriers collected by the current collecting electrode 5b on the opposite side with respect to the adjacent first bus bar electrode 4c can be more efficiently collected. Can tell. Moreover, since the finger part 5c is formed so that it may cross the 1st bus-bar electrode 4c, generation | occurrence | production of the crack along the longitudinal direction of the 1st bus-bar electrode 4c can be reduced.

  On the other hand, as shown in FIG. 3A, in the solar cell element, the through holes 3 are formed so as to substantially coincide with the positions where the first bus bar electrodes 4c are formed in plan view. Furthermore, the light receiving surface side electrode 4a is uniformly formed on the first surface as a plurality of linear patterns connected to all the through-hole electrodes 4b.

  The plurality of solar cell elements 10 are electrically connected by leads 11 to form a string 40. For example, the strings 40 are electrically connected by connecting the first bus bar electrodes 4 c and the second bus bar electrodes 5 a of the adjacent solar cell elements 10 by the leads 11. At the time of connection, flux is often applied to the first bus bar electrode 4c and the second bus bar electrode 5a in advance in order to improve soldering.

  As the lead 11, for example, a surface of a low resistance wiring material such as copper or aluminum, which is solder-coated with a thickness of about 20 μm to 70 μm by plating or dipping, is cut into an appropriate length and used.

  The lead 11 has a substantially linear shape, a bent shape in sectional view of two adjacent solar cell elements in order to release stress generated during thermal expansion / contraction due to temperature change after installation, Alternatively, one having a notch may be used. As such a lead 11, a copper foil coated with solder and bent into an appropriate shape can be used.

  When two adjacent solar cell elements are a first solar cell element and a second solar cell element each having a first semiconductor substrate and a second semiconductor substrate, the lead 11 having a bent portion is The first electrode 4 on the semiconductor substrate and the second electrode 5 on the second semiconductor substrate are soldered. The lead 11 includes a plurality of first connection surfaces connected to the first electrode 4 on the first semiconductor substrate, a first separation portion between the two first connection surfaces, and an adjacent second semiconductor substrate. A plurality of second connection surfaces connected to the second electrode 5 and a second separation portion between the two second connection surfaces. In a state where a plurality of solar cell elements are arranged adjacent to each other, the first connection surface of the lead 11 is connected to each of the first electrodes 4 on the first semiconductor substrate, and on the adjacent second semiconductor substrate. When the second connection surface of the lead 11 is connected to each of the second electrodes 5, there is a gap between the second electrode 5 on the first semiconductor substrate and the second separated portion of the lead 11. Become. By forming this gap on the second electrode 5 on the first semiconductor substrate, the lead 11 and the second electrode 5 on the first semiconductor substrate are less likely to be in direct contact with each other. Short circuit in the element can be reduced. When a polycrystalline silicon solar cell element of about 150 to 200 mm square is used, the lead 11 has a width of about 1 mm to 3 mm, a thickness of about 0.1 mm to 0.6 mm, and a length of about 250 mm to 360 mm. is there.

  Moreover, when using a substantially linear lead for the back contact type solar cell element, an insulating layer may be provided in the gap between the first bus bar electrodes 4c. As an insulating layer, for example, a part where an insulating tape such as a fluororesin or a polyimide resin represented by PTFE (polytetrafluoroethylene) having high heat resistance is attached to the lead 11 or a connection with the lead 11 is to be avoided In addition, there is a method in which a solder resist, a glass paste, or the like is applied and baked by screen printing. At this time, an insulating layer may be provided on a part of the first bus bar electrode 4c. Further, by providing the finger portion 5c and the insulating layer in the gap between the first bus bar electrodes 4c, the generation of cracks along the longitudinal direction of the first bus bar electrode 4c can be further reduced.

Further, when the back contact type solar cell element is connected to the first bus bar electrode 4c using the concavo-convex lead 11, the lead 11 is partially bent so as not to connect to the gap between the first bus bar electrodes 4c. Thus, a connection part and a non-connection part are provided. The length of the connection portion and the non-connection varies depending on the electrode shape of the solar cell element. For example, the length of the connection portion may be 3 mm to 20 mm, and the length of the non-connection portion may be 1 mm to 10 mm. The length of the part and the non-connection part may be the same or different. Further, the difference in height between the connection portion and the non-connection portion may be 0.2 mm or more and 1 mm or less. Further, even when the concavo-convex lead 11 is used, the leakage defect can be further reduced by providing an insulating layer in the gap between the first bus bar electrodes 4c.
≪Solar cell module manufacturing method≫
As shown in FIG. 4, the manufacturing process of the solar cell module according to the first embodiment of the present invention includes a process of soldering leads to electrodes of a plurality of semiconductor substrates in the first area 41, and the leads are soldered. There are a step of sucking and transferring the plurality of attached semiconductor substrates, and a step of cooling the plurality of transferred semiconductor substrates in the second area 42 while being sucked and fixed. And after cooling, it is made to convey to the 3rd area 43 used as next processes, such as an inspection process.

  The manufacturing method of the solar cell module according to the first embodiment of the present invention will be described in detail below.

<Lead fixing process>
First, as shown in FIG. 5, between the first stage 12 and the fixing member 13, the solar cell element 10 and the lead 11 are fixed by contact with solder.

  Specifically, for example, the solar cell element 10 and the lead 11 constituting the solar cell string 20 are fixed between the first stage 12 and the fixing member 13 and placed on the base 14. Here, as a fixing method, the weight of the fixing member 13 may be used, or a fixing jig for fixing the first stage 12 and the fixing member 13 may be further provided. These members may be used to be sandwiched between the first stage 12 and the fixing member 13.

  The first stage 12 of the present embodiment has a mechanism that has predetermined pores and can generate a negative pressure through the pores. Thereby, the arranged solar cell element 10 and the lead 11 can be adsorbed to the pore side by a negative pressure, and the positional deviation of the lead 11 with respect to the solar cell element 10 can be reduced. Further, the first stage 12 is preferably provided with an exhaust groove or an exhaust hole that allows ventilation to the outside on the surface on which the solar cell element 10 and / or the lead 11 is placed. It is possible to reduce the contamination of the jig due to the flux gas and to reduce the defect rate. In order to discharge the flux gas more efficiently, for example, a mechanism for sucking air through the above-described exhaust groove or exhaust hole led out of the first stage 12 may be provided.

  The first stage 12 used in the present embodiment is made of, for example, a metal such as iron, stainless steel, or aluminum, a light metal, a ceramic plate, or the like. In addition, a predetermined through hole 16 is formed on the surface on which the lead 11 is placed so that the above-described presser bar 15 can be inserted. By inserting the through hole 16, the lead 11 is connected to the solar cell element. 10 can be pressed with an appropriate force.

  Further, as shown in FIG. 6, from the viewpoint of alleviating thermal stress that may occur between the electrodes of the solar cell element 10, in the case of using the lead 11 that is formed in irregularities, the first lead 11 is placed. It is preferable that the surface of one stage 12 has an uneven shape corresponding to the shape of the lead 11. In FIG. 6, the shape of the leads 11 located between the solar cell elements 10 is flat.

  Further, as shown in FIG. 7, a groove 17 is preferably formed on the surface of the first stage 12 at a position where the lead 11 is placed. It is possible to place the lead 11 well and reduce the deviation from the position. As described above, when the first stage 12 has the groove 17, the uneven shape and the through hole 16 may be formed at the bottom of the groove 17.

  The fixing member 13 used in the present embodiment has a function of pressing and fixing the solar cell element. The fixing member 13 is either a member having high light transmission properties such as glass or a member having high heat conductivity such as aluminum as long as the fixing member 13 can efficiently transfer the heat given by the heating means to the solder. Also good. When using an infrared irradiation device as a heating means, it is preferable to use a member that efficiently transmits infrared rays, for example, a glass material such as soda-lime glass, borosilicate glass, and quartz glass, and particularly, the surface is scratched. Tempered glass is preferable from the viewpoint of suppressing a decrease in infrared transmittance.

  Here, it is preferable that the fixing member 13 is embossed on the surface, or a light-shielding material such as a reflective paint is disposed on the surface, thereby appropriately controlling the temperature distribution of the solar cell element 10 in the connection step described later. It becomes possible.

When the solar cell string 20 is fixed by the weight of the fixing member 13, the fixing member 13 may have a weight that does not easily cause cracks in the solar cell element 10. The thickness is adjusted so that the stress is 7.35 × 10 ⁻³ N / cm ^{2 to} 2.45 × 10 ⁻² N / cm ² .

  The base 14 used in the present embodiment is made of, for example, a metal such as iron, stainless steel, or aluminum, a light metal, ceramics, or the like, and a pressing rod 15 for pressing the lead 11 against the electrode of the solar cell element 10 is a solar cell element. A plurality of electrodes are embedded corresponding to the connection positions of the ten electrodes and the leads 11. The presser bar 15 preferably includes a spring, and is controlled to press the lead 11 toward the solar cell element 10 with an appropriate force by adjusting the force of the spring. In particular, when the groove 17 formed on the surface of the first stage 1 is formed deeper than the thickness of the lead 11, the lead 11 is pressed against the electrode of the solar cell element 10 by the pressing bar 15. Therefore, the magnitude and time of the pressing load applied to the lead 11 and the solar cell element 10 can be appropriately controlled.

  In addition, when the solder is heated and melted in the connection step described later, it is preferable to preheat the solder to a predetermined temperature in advance. For example, the base 14, the first stage 12, the fixing member 13, etc. A device may be incorporated. As a result, even when the ambient temperature is low, a part of the heat applied to connect the solar cell element 10 and the lead 11 is released to the surroundings, thereby causing poor soldering or the like. This can be effectively reduced.

  As described above, the first stage 12 and the fixing member 13 can be fixed between the first stage 12 and the fixing member 13 with the lead 11 in contact with the solar cell element 10. It is configured so that it can be soldered. With such a configuration, it is possible to reduce the deformation of the solar cell element 10 due to heat at the time of soldering, and it is possible to make the solar cell element 10 difficult to shift during conveyance.

  As described above, the reliability of the connection between the solar cell element 10 and the lead 11 can be improved by performing the steps described below with the solar cell element 10 and the lead 11 fixed.

  In particular, as shown in FIG. 3, a back contact type solar cell in which through-holes are provided in the substrate at regular intervals and the first bus bar electrode 4c and the second bus bar electrode 5a are provided close to each other on the back surface side. In the case of the element 10, the load on the solar cell element 10 and the lead 11 can be reduced, and the leakage current or short circuit generated when the lead 11 is connected to the electrode having the opposite polarity due to the displacement of the connection position of the lead 11 can be reduced.

<Solar cell element and lead connection step>
Next, with the solar cell element 10 and the lead 11 fixed as described above, the solder is heated and melted to electrically connect the solar cell element 10 and the lead 11. As a result, it is possible to reduce the occurrence of misalignment due to the difference in thermal expansion coefficient between the solar cell element 10 and the lead 11 in the connection process.

  Specifically, as shown in FIGS. 6 and 8, by irradiating near infrared rays from a lamp 18 attached in a movable state with respect to the rail 19, the solar cell element 10 of the solar cell element 10 can be seen from above through the fixing member 13. Electrical connection by soldering is performed by applying heat to the solder located on the back side.

  That is, the near infrared ray irradiated from the lamp 18 is transmitted through the fixing member 13 to heat the soldered portion of the solar cell string 20, and the solder on the surface of the lead 11 is melted to cause the first bus bar electrode of the solar cell element 10. 4c, the solar cell element 10 and the lead 11 are soldered by adhering to the second bus bar electrode 5a.

  As the heating means, in the case of the back contact type solar cell element 10 in which the positioning accuracy between the lead 11 and the electrode is required, it is preferable to use an infrared irradiation device with a small dynamic load.

  In particular, when the solar cell element 10 and the lead 11 are fixed with the first stage 12 and the fixing member 13 made of glass, the infrared irradiation device uses near infrared rays from the viewpoint of transparency to the object. It is preferable to use what can be irradiated. In addition, near infrared rays can give a high energy density to an object to be heated and raise the temperature in a relatively short time, so that the processing speed can be improved and the power consumption can be reduced. As the near-infrared light source, for example, a halogen lamp or a xenon lamp can be used. As the heating means other than the infrared light, for example, a laser light source such as a semiconductor laser or a YAG laser can be used.

  Note that the heating means for heating and melting the solder is not limited to the above-described infrared irradiation apparatus, and a pressing device having a temperature raising mechanism can be used. By using a plurality of heating means in combination, production efficiency can be improved. It is preferable to increase. When heating with a pressing device having a temperature raising mechanism sandwiched from both sides of the solar cell element 10 by the pressing device, the pressing position of the pressing device is adjusted by matching the pressing position of the pressing device between the light receiving surface and the back surface. It is preferable to reduce the damage of the solar cell element 10 due to the shearing force due to the deviation.

<Cooling process of solar cell string>
Next, the solar cell element 10 is transported and cooled in a flat state by the method described below.

  First, as shown in FIG. 9A, in the first area, the fixing member 13 is removed from the top of the solar cell string 20 while the solar cell string 20 is adsorbed to the first stage 12.

  Then, as shown in FIG. 9B, the transport plate 21 is disposed on the solar cell string 20, and thereafter, the solar cell string 20 is sucked and fixed by the transport plate 21, so that the solar cell string 20 is flattened. Hold on. Specifically, by providing a suction mechanism on the transport plate 21, the first stage 12 is released from suction after the solar cell string 20 is attracted to the transport plate 21. As a material of the transport plate 21, for example, a metal such as iron, stainless steel, and aluminum, a light metal, a ceramic plate, or the like is used.

  Finally, as shown in FIG. 9C, the transport plate 21 holding the solar cell string 20 is transported from the first stage 12 to the second area, and the solar cell string 20 is, for example, 1 ° C. / It is cooled to 50 ° C. or less, preferably to room temperature, at a cooling rate of sec to 10 ° C./sec. Here, “transport” means that the transport plate 21 holding the solar cell string 20 is moved from one region to another, and includes lifting the solar cell string 20. The “second area” refers to another area where the solar cell string 20 is conveyed, and includes an upper area of the first area that is located when the solar cell string 20 is lifted.

  Thus, the solar cell string 20 in the present embodiment is always in a state of being fixed flat during fixing (solder welding), conveyance, and cooling between the lead 11 and the solar cell element 10. As described above, the solar cell element 10 is mainly made of a silicon substrate, and the lead 11 is mainly made of a low-resistance wiring material such as copper or aluminum. Therefore, the lead 11 is larger than the thermal expansion coefficient of the solar cell element 10. The coefficient of thermal expansion is greater. For this reason, when the temperature of the solar cell string 20 decreases after the solar cell element 10 and the lead 11 are soldered, the lead 11 tends to contract more than the solar cell element 10 due to the difference in thermal expansion coefficient. A stress that tends to bend the battery element 10 is generated.

  However, according to the present embodiment, since the solar cell string 20 is fixed and restrained flat, tensile thermal stress is applied to the lead 11, and plastic strain in the tensile direction is generated in the lead 11. Thereby, the contraction length of the solar cell element 10 and the lead 11 accompanying the cooling of the solar cell string 20 is leveled, and the warpage and cracking of the solar cell element 10 are alleviated. If such a thermal stress is used, a tensile stress is applied by being dispersed at the portion where the solar cell element 10 and the lead 11 are joined. Therefore, the stress concentration is suppressed and the solar cell element when reducing warpage is obtained. Can reduce the load. In this way, the solar cell string 20 with the yield improved by reducing the warpage of the solar cell element can be conveyed to the next step such as inspection.

Moreover, since it can use for the connection process of the next solar cell element 10 and the lead | read | reed 11 without reducing the temperature of the 1st stage 12, the fixing member 13, and the base 14 in high temperature, productivity falls too much. Therefore, it is possible to reduce the occurrence of poor soldering. In particular, when a lead-free solder, for example, a lead-free solder made of Sn—Ag—Cu is used, an alloy such as Ag ₃ Sn or Cu ₆ Sn ₅ existing in the solder grows in a needle shape under a high temperature environment. In this embodiment, the solar cell string 20 is moved to a different region from the first stage 12 at a high temperature. Progress can be reduced.

  Further, as shown in FIG. 6, the lead 11 may be bent, and a concave connection portion 11a and a convex non-connection portion 11b may be provided. Compared to a lead that does not have a bent portion, the lead 11 having the bent portion is elongated by a small stress due to the change in the convex shape of the non-connecting portion 11b. The warpage of the solar cell element 10 can be reduced by leveling the contraction length of the solar cell element 10 and the lead 11 after cooling, while reducing the occurrence of cracks.

  Next, a specific cooling method will be described.

  For example, as shown in FIG. 10A, the solar cell string 20 can be cooled by providing an air blow device 22 below the transport plate and injecting a cooling gas toward the solar cell string 20. it can. Further, as shown in FIG. 10 (b), the conveying plate 21 is provided with an opening communicating with the outside so as to form, for example, a lattice, and the air blowing device 22 is disposed above and below the conveying plate. The cooling can be performed even faster by providing and injecting the cooling gas toward the solar cell string 20. In addition, the shape of an opening part should just be a shape which does not inhibit an adsorption | suction mechanism, for example, a rectangle, a circle, an ellipse, and a polygon may be sufficient.

  In addition, the air blow device 22 may be provided in the cooling region, and after the solar cell string 20 is transported to the cooling region, the cooling gas may be injected to cool the air blow device 22 or during the transport of the next process. By cooling the solar cell string 20 while transporting the solar cell string 20, the cooling rate of the solar cell string 20 can be further increased and the productivity can be improved.

  Moreover, the solar cell string 20 can be cooled more efficiently by providing a cooling mechanism in the transport plate 21. The cooling mechanism is achieved by flowing cooling water or cooling gas through the transport plate 21. The solar cell string 20 is not cooled only by the transport plate 21, but by using the air blow device 22 provided below, the cooling rate of the solar cell string 20 is further increased and the productivity can be improved. When the cooling mechanism is provided on the transport plate, the material of the transport plate 21 is, for example, a metal having high thermal conductivity, heat conductive rubber, magnesium oxide, beryllium oxide, or the like.

  Next, another form of the cooling process will be described. As shown in FIG. 11A, a second stage 23 having a temperature lower than that of the first stage is prepared, and the solar cell string 20 is placed on the second stage 23 by the transport plate 21. At this time, by providing an adsorption mechanism in the second stage 23, the solar cell string 20 can be cooled in a state of being kept flat even if it is separated from the solar cell string 20 from the transport plate 21. As a cooling mechanism, a cooling water or a cooling gas is allowed to flow through the second stage 23, and the solar cell string 20 is cooled by the second stage 23. As shown in FIG. Examples include a mechanism in which the air blow device 22 provided above the solar cell string 20 is cooled after the 21 is separated from the solar cell string 20. In particular, when the solar cell string 20 fixed on the second stage 23 having the cooling mechanism is cooled by the air blow device 22, the cooling rate of the solar cell string 20 can be increased and the productivity can be improved. As the second stage 23, a metal having high heat conductivity, heat conductive rubber, magnesium oxide, beryllium oxide, or the like is used.

  Below, 2nd embodiment which concerns on the manufacturing method of the solar cell module of this invention is described.

  In the back contact solar cell element 10, when the lead is connected to the solar cell element, the lead 11 is not connected to the first surface 1 a, so the solar cell element is convex toward the first surface 1 a. It tends to warp. In the present embodiment, the state in which the solar cell element 10 is warped in the direction opposite to the direction warped by the connection of the lead 11 during the cooling step is fixed, and after cooling to 50 ° C. or less, preferably room temperature, the fixing is performed. The warp of the solar cell element 10 can be further reduced by canceling. As a specific method, as shown in FIG. 12A, the transport plate 21 has a convex portion on the side in contact with the first surface of the solar cell element 10. In the cooling step, the first surface of the solar cell element 10 may be pushed by the convex portion of the transport plate 21. Here, “pressing” the solar cell element 10 with the convex portion of the plate means that the convex portion applies a force to the first surface of the solar cell element. Alternatively, the position of the suction mechanism provided on the transport plate 21 may be changed in the height direction so that the solar cell element becomes concave toward the first surface 1a.

  Further, as shown in FIG. 12B, the first stage 12 is provided with a shape in which the shape of the surface in contact with the solar cell element 10 is concave at a position in contact with the central portion of the solar cell element 10. Also good. By matching the shape of the first stage 12 to the transport plate 21, the suction failure is reduced, and the solar cell element 10 can be sucked according to the shape of the transport plate 21. The shape of the fixing member 13 is more preferably matched to the first stage 12.

  Further, as shown in FIG. 13, by forming the lead 11 located between the solar cell elements 10 in a convex shape, when the solar cell element 10 is warped, or when the fixation is released after cooling, The stress applied to the end of the battery element can be reduced.

  In addition, when the second stage 23 having a temperature lower than that of the first stage is prepared and the solar cell string 20 is placed on the second stage 23 and cooled by the transport plate 21, the second stage 23 is The step of contacting the second surface of the battery element 10 has a recess, and the second surface of the solar cell element 10 is adsorbed to the recess of the second stage 23 in the step of fixing to the second stage 23. Let Adsorption to the concave portion can be performed, for example, by providing a hole in the inner wall of the concave portion, generating a negative pressure through the hole, and adsorbing the inner surface of the concave portion. Furthermore, a groove may be formed in the second stage 23 so that the second stage 23 and the lead 11 do not contact each other.

  Furthermore, as shown in FIG. 14, it is only necessary to warp the solar cell element 10 in a concave shape toward the first surface 1 a at least only in the connection direction of the lead 11, thereby reducing the warpage of the solar cell element 10 due to the connection of the lead 11. Thus, the flat solar cell string 20 with less warpage can be formed.

  Below, 3rd embodiment which concerns on the manufacturing method of the solar cell module of this invention is described, referring FIG. This embodiment is different from the first embodiment described above in the cooling step and the processing step after the cooling step.

  In the present embodiment, in the cooling step, for example, using an apparatus as shown in FIG. 15, the solar cell string 20 is −20 ° C. to −80 ° C. below zero degrees Celsius, more preferably −30 ° C. to −50 ° C. Cooling with. In FIG. 15A, the solar cell string 20 using the back contact type solar cell element 10 is adsorbed by the adsorber 25 toward the upper plate 21 toward the upper plate, and is cooled from the lower side as viewed from the side. A cross-sectional view is shown. FIG. 15B is a cross-sectional view of FIG. 15A viewed from the A-A ′ cross section.

  For the cooling below zero degrees Celsius as described above, for example, a heat exchanger installed below or air introduced from the tube 28 as shown in FIG. 15A is blown to the dry ice 27 stored in the cooling container 26. This is done by circulating as cold air. Thus, if the solar cell string 20 is cooled and fixed to the plate 21 while being flatly adsorbed to the plate 21, the thermal stress and plastic strain generated in the lead 11 are increased as compared with cooling to about room temperature. Thereby, the length of the solar cell element 10 and the lead 11 at normal temperature can be further leveled, the internal force can be reduced, and the warpage of the solar cell element 10 can be reduced. In addition to adsorbing the solar cell string 20 toward the upper plate 21, the solar cell string 21 is adsorbed and fixed by the adsorber 25 toward the lower plate 21 as shown in FIG. Cooler air 29 may be introduced and cooled. Further, the cooling of the solar cell string 20 does not necessarily have to be performed continuously by continuously fixing the solar cell element 10 and the lead 11 with the same plate 21 after soldering. After cooling, the solar cell string 20 may be fixed to a different plate 21 and cooled to below zero degrees Celsius.

    Further, if the solar cell string 20 cooled to below 0 degrees Celsius is taken out from the cooling container 26 while being fixed to the plate 21, it takes time until the temperature reaches room temperature because the heat capacity of the plate 21 is large. The solar cell string 20 may be wetted. For this reason, the solar cell string 20 cooled to below zero degrees Celsius is taken out from the cooling container 26 after the fixation with the plate 21 is released from the viewpoint of reducing condensation that occurs when the plate 21 having a large heat capacity is cooled to room temperature. Is preferred. Since the solar cell string 20 released from the fixation with the plate 21 has a small heat capacity, it can be brought to room temperature before condensation occurs due to moisture in the air.

  On the other hand, in order to further reduce the dew condensation that occurs on the plate 21 described above, when the solar cell string 20 that has been set to zero degrees Celsius or less in the cooling step is taken out from the cooling container 26 while being fixed to the plate 21, dry hot air is blown Then, it is preferable to raise the temperature of the solar cell string. As this hot air, it is preferable to use a hot air of 35 ° C. to 45 ° C. from the viewpoint of efficiently reducing condensation while suppressing a load such as a thermal shock applied to the solar cell string 20.

  Below, 4th embodiment which concerns on the manufacturing method of the solar cell module of this invention is described, referring FIG. This embodiment is different from the first embodiment in that the solar cell string 20 is sandwiched and fixed flatly by a pair of plates 21. FIG. 16A is an exploded perspective view showing a state in which the solar cell string 20 is sandwiched and fixed flatly by the plate 21 including the base 51, the low friction member 52, and the buffer material 53. FIG. 16B illustrates the present embodiment, and is a cross-sectional view showing a state in which the solar cell string 20 is sandwiched and fixed by the plate 21, and FIG. 16C is a perspective view seen from above. . The base 51 is made of, for example, a light metal such as aluminum, ceramics, glass, or the like. Moreover, the low friction member 52 is comprised, for example with the polyimide film, the polyethylene film, and the fluororesin film. In addition, as the buffer material 53, for example, urethane foam, silicon rubber, EPDM rubber, or the like can be used. In this embodiment, unlike the embodiments described above, there is an advantage that equipment such as the suction tool 25 is unnecessary and can be realized by a simple jig. Thus, the solar cell string 20 clamped and fixed flat by the plate 21 can be stacked and stored in a freezer or the like, for example, and cooled. While being able to carry out with the freezer which is easy to acquire, since a lot of solar cell strings 20 can be cooled at once, tact time can be shortened.

  Further, if the outer diameter of the contact portion of the plate 21 with the solar cell element 10 is made slightly smaller than that of the solar cell element so as to avoid the periphery of the lead connection portion at the end of the solar cell element, the plate 21 is clamped and fixed. It is possible to reduce cracks that are likely to occur in the periphery of the portion where the end of the solar cell element 10 and the lead 11 overlap due to the stress of. Specifically, for example, as shown in FIG. 16C, the low friction member 52 and the buffer material 53 may be made smaller at the D portion than the solar cell element 10. Moreover, in this embodiment, you may use for cooling from solder welding temperature to room temperature besides using it for cooling to below 0 degree | times with a freezer etc.

  Below, 5th embodiment which concerns on the manufacturing method of the solar cell module of this invention is described, referring FIG. This embodiment is different from the fourth embodiment in that the solar cell string 20 is clamped and fixed by a plate 21 that warps and is cooled. FIG. 17A shows a state before the solar cell string 20 is sandwiched and fixed by the plate 21, FIG. 17B shows a state where the solar cell string 20 is sandwiched and fixed by the plate 21, and FIG. The state where the fixing of the solar cell string 20 by the plate 21 is released is shown. Here, the solar cell string 20 is obtained by soldering and connecting leads 11 to a plurality of back contact type solar cell elements 10. The plate 21 includes a base 51 and a plurality of convex portions 24 provided on the surface thereof, and a plurality of the convex portions 24 are also provided on the surface facing the solar cell string 20. The solar cell string 20 is sandwiched and fixed from above and below by the convex portions 24 so that the lead 11 is warped outside the curve, and tensile stress is mechanically applied to the lead 11.

  Furthermore, the solar cell string 20 is sandwiched and fixed to the plate 21 and cooled while being restrained in a bent state, whereby thermal stress can be applied. The thermal stress applied to the lead 11 is applied to the tensile direction because the solar cell element 10 and the lead 11 are joined and the coefficient of thermal expansion of the lead 11 is larger than that of the solar cell element 10. Arise. In this embodiment, for example, it can be used for cooling from the solder welding temperature to room temperature, or cooling from room temperature to zero degrees Celsius or less.

  In this way, by applying a tensile thermal stress to the lead 11 in addition to a mechanical tensile stress, the lead 11 causes a plastic strain in a tensile direction larger than that when the solar cell string 20 is fixed flat. be able to. Thereby, even if the difference in thermal expansion coefficient between the solar cell element 10 and the lead 11 is large and the warpage of the solar cell element 10 is large, the contraction length of the solar cell element 10 and the lead 11 at normal temperature is leveled. Thus, the warpage of the solar cell element 10 can be reduced. Further, the thermal stress to the lead 11 is generated in the entire interface where the solar cell element 10 and the lead 11 are joined. Thereby, stress concentration can be suppressed and cracking of the solar cell element 10 can be reduced.

  The effect of the present embodiment can be suitably obtained as long as the solar cell string 20 is fixed by being bent so that the leads 11 are on the outside. More preferably, the solar cell element is as shown in FIG. It is preferable to perform four-point bending per 10 sheets. FIG. 18 (a) shows a bending moment diagram per solar cell element 10 when the solar cell string 20 is fixed as shown in FIG. 17, and FIG. 18 (b) shows the tensile force generated on the lead 11 at the same portion. The stress diagram of is shown. For comparison, FIG. 18 (c) shows a bending moment diagram when the solar cell string is a three-point bending per solar cell element, and FIG. 18 (d) shows the bending moment of FIG. 18 (c). A tensile stress diagram of the lead 11 when it occurs is shown.

In FIG. 18B and FIG. 18D, the solid line A indicates the mechanical tensile stress on the lead 11 that occurs when the solar cell string 20 is fixed to the plate 21, and the broken line B indicates the lead 11 due to cooling. The alternate long and short dash line C indicates the sum of the mechanical tensile stress and the tensile thermal stress. In a portion where the sum of the mechanical tensile stress and the tensile thermal stress exceeds the yield stress σ _s of the lead 11, a tensile plastic strain is generated in the lead in proportion to the tensile stress. As shown in FIG. 18B, the tensile stress generated in the lead in the four-point bending has a certain interval between the convex portions 24a and 24b. That is, a constant plastic strain is generated in a section where the tensile stress is constant, and the warp can be returned uniformly in a wide section. On the other hand, in the case of three-point bending, stress concentration is likely to occur because the stress is not uniform. Thus, by curving so that it may be a four-point bend per one solar cell element 10, the curvature of a solar cell string can be reduced, suppressing the crack of a solar cell element.

It is a perspective view which shows an example of a solar cell module, (a) is an exploded perspective view which shows the laminated structure of a solar cell module from the light-receiving surface side, (b) is a solar cell element and a lead before a connection process from the back side. The perspective view to show, (c) is a perspective view which shows the solar cell element and lead | read | reed after a connection process from a back surface side. It is a figure which shows an example of a solar cell element, (a) is the figure seen planarly from the light-receiving surface side, (b) is the figure seen planarly from the non-light-receiving surface side. It is sectional drawing which shows an example of a solar cell element. It is a figure which shows an example of a solar cell element, (a) is the figure seen planarly from the light-receiving surface side, (b) is the figure seen planarly from the non-light-receiving surface side. It is a figure explaining embodiment of the manufacturing method of a solar cell module. It is a perspective view for demonstrating one Embodiment of the manufacturing method of a solar cell module, and is an exploded perspective view for demonstrating a fixing process especially. It is sectional drawing explaining the connection process of a solar cell element and a lead | read | reed. It is a disassembled perspective view which shows another example of a fixing process with the manufacturing method of a solar cell module. It is a perspective view for demonstrating one Embodiment of the manufacturing method of a solar cell module. (A)-(c) is a figure explaining one Embodiment of the cooling process of the manufacturing method of a solar cell module. (A)-(b) is a figure for demonstrating one Embodiment of the cooling process of the manufacturing method of a solar cell module. (A)-(b) is a figure explaining another embodiment of the cooling process of the manufacturing method of a solar cell module. (A)-(b) is a figure explaining another embodiment of the cooling process of the manufacturing method of a solar cell module. It is a figure explaining another embodiment of the cooling process of the manufacturing method of a solar cell module. It is a figure explaining another embodiment of the cooling process of the manufacturing method of a solar cell module. It is a figure explaining another embodiment of the cooling process of the manufacturing method of a solar cell module. It is a figure explaining another embodiment of the cooling process of the manufacturing method of a solar cell module. It is a figure explaining another embodiment of the cooling process of the manufacturing method of a solar cell module. It is a figure explaining the effect of another embodiment of the cooling process of the manufacturing method of a solar cell module.

Explanation of symbols

10: Solar cell element 11: Lead 12: First stage 20: Solar cell string 21: Plate 23: Second stage 24: Convex 25: Suction tool 26: Cooling vessel 27: Dry ice 28: Tube 30: Sun Battery module
51: Base 52: Low friction member 53: Buffer material

Claims (11)

Preparing a lead and a plurality of solar cell elements including a first surface and a second surface on the back side of the first surface and having electrodes on the second surface;
Soldering the leads to the electrodes of the plurality of solar cell elements;
Fixing the plurality of solar cell elements to which the leads are soldered to a plate;
A cooling step for cooling the lead and the solar cell element fixed to the plate;
A step of releasing fixation of the plate, the cooled lead and the solar cell element, and a method of manufacturing a solar cell module ,
The plate has a convex portion on a side in contact with the first surface of the solar cell element, and in the cooling step, the first surface of the solar cell element is the convex portion of the plate. The manufacturing method of the solar cell module to press . The cooling step is a method for manufacturing a solar cell module according to claim 1, wherein the cooling below zero degrees Celsius. Wherein after the cooling step, the method for manufacturing the solar cell module according to claim 1, wherein further comprising the step of raising the temperature by blowing hot air and fixed the lead to the plate to the solar cell element . The step of fixing the lead and the solar cell element to the plate, the method of manufacturing a solar cell module according to any one of claims 1 to 3, characterized in that for fixing by suction the solar cell element to the plate. The process of fixing the said lead and the said solar cell element to a plate clamps and fixes the said solar cell element with a pair of plate, The manufacturing of the solar cell module in any one of Claims 1-3 characterized by the above-mentioned. Method. The plurality of solar cell elements fixed to the plate are adsorbed and fixed to the plate having an opening communicating with the outside, and the plurality of solar cell elements are cooled through the opening. The manufacturing method of the solar cell module of Claim 1 . Method of manufacturing a solar cell module according to claim 1, said second surface of said solar cell element, and a plurality of electrodes of different polarities are provided. The said solar cell element is provided with the through-hole by which the conduction | electrical_connection part was formed inside, The manufacturing method of the solar cell module of Claim 7 characterized by the above-mentioned. When two adjacent solar cell elements among the plurality of solar cell elements are a first solar cell element and a second solar cell element, the first solar cell element has the first polarity. And the second solar cell element has the electrode having the second polarity, has a bent portion in a cross-sectional view in the arrangement direction of the two adjacent solar cell elements, and is linear in a plan view. The method of manufacturing a solar cell module according to claim 7 or 8 , wherein the lead having a shape is soldered to the first electrode and the second electrode. 10. The solar cell element according to claim 9 , wherein in the step of soldering the lead to the electrode of the plurality of solar cell elements, the bent portion of the lead is disposed on the solar cell element. Production method. In the step of soldering the lead to the electrode of the plurality of solar cell elements, according to claim 10, the bent portion of the lead, characterized in that disposed between two solar cell elements adjacent ones Manufacturing method of solar cell element.

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