JP4467466B2 - Manufacturing method of solar cell module - Google Patents

Description

  The present invention relates to a solar cell module in which solar cell elements are connected by an interconnector.

  A general structure of the solar cell element is shown in FIG. FIG. 10A is a diagram showing a cross-sectional structure of the solar cell element S, and FIG. 10B is a conventional solar cell module T configured by combining the solar cell elements S of FIG. 10A. . Moreover, FIG.10 (c) is the elements on larger scale of the internal structure of the solar cell module T of FIG.10 (b). FIG. 9 is a diagram showing an example of the electrode shape. FIG. 9A is a light receiving surface side (front surface) of the solar cell element S, and FIG. 9B is a non-light receiving surface side (back surface) of the solar cell element S. It is.

  Such a solar cell element S is manufactured as follows.

First, a p-type semiconductor substrate 1 made of single crystal silicon or polycrystalline silicon having a thickness of about 0.2 mm to 0.5 mm and a size of about 100 mm to 150 mm square is prepared. Then, an n-type diffusion layer 2 is provided on the semiconductor substrate 1, and a pn junction is formed between the semiconductor substrate 1 and the p-type semiconductor substrate 1. In such a diffusion layer 2, the semiconductor substrate 1 is placed in a diffusion furnace and heated in phosphorus oxychloride (POCl ₃ ), whereby phosphorus atoms that are n-type impurities are formed on the entire surface of the semiconductor substrate 1. By diffusing, it can be formed as a diffusion layer 2 having a thickness of about 0.2 μm to 0.5 μm. Thereafter, the diffusion layer portions on the side surface portion and the bottom surface portion are removed.

  On the light receiving surface side of the solar cell element S, for example, an antireflection film 3 made of a silicon nitride film is formed. Such an antireflection film 3 is formed, for example, by a plasma CVD method or the like, and also has a function as a passivation film.

  Then, the front electrode 4 and the back electrode 5 are simultaneously formed by applying and baking a silver paste on the surface of the semiconductor substrate 1 and applying an aluminum paste and a silver paste on the back surface.

  As shown in FIG. 9A, the surface electrode 4 is composed of a surface bus bar electrode 4a for extracting output from the surface, and a surface finger electrode 4b for current collection provided so as to be orthogonal thereto. Further, as shown in FIG. 9B, the back electrode 5 is composed of a back bus bar electrode 5a and a back collecting electrode 5b for extracting output from the back.

  The back surface collecting electrode 5b is formed by applying and baking an aluminum paste by a screen printing method. At this time, aluminum acting as a p-type impurity element diffuses into the semiconductor substrate 1 of silicon. Thus, the high-concentration back surface electric field region 6 is formed. This back surface electric field region 6 is called a BSF layer (Back Surface Field) and has a function of preventing minority carrier recombination on the back surface, improving carrier collection efficiency, and improving solar cell characteristics. Moreover, the front surface bus bar electrode 4a, the front surface finger electrode 4b, and the rear surface bus bar electrode 5a are formed by a method in which a silver paste is applied and baked by a screen printing method. The surface electrode 4 may be formed by etching away a portion corresponding to the electrode of the antireflection film 3 or may be formed directly from above the antireflection film 3 by a technique called fire-through. .

  In addition, the electrodes of these solar cell elements S may be covered with solder in order to facilitate wiring for taking out the output to the outside or to maintain the durability of the electrodes. The dip method, jet type, etc. are adopted.

  Since one solar cell element generates a small electrical output, it is necessary to connect a plurality of solar cell elements S in series or in parallel so that a practical output can be taken out. FIG. 10B shows a solar cell module T obtained by combining the solar cell element S shown in FIG. 10A as a general solar cell module.

  As shown in FIG. 10B, the plurality of solar cell elements S are electrically connected by the interconnector 27. The interconnector 27 is connected to a part of the front bus bar electrode 4a and the back bus bar electrode 5a of the solar cell element S by partial welding or hot welding such as hot air or a soldering iron to connect the solar cell elements S to each other. ing. As the interconnector 27, for example, a copper foil having a thickness of about 50 μm to 500 μm that is coated with a solder of about 20 μm to 70 μm on the entire surface is cut into a predetermined length.

  Thereafter, the solar cell module T is configured by being hermetically sealed between the translucent panel 8 and the back surface protective material 10 with a filler 9 mainly composed of ethylene vinyl acetate copolymer (EVA). The output of the solar cell module T is connected to the terminal box 12 via the output wiring 11. FIG. 10 (c) shows a partially enlarged view of the internal structure of the solar cell module T of FIG. 10 (b).

As shown in FIG.10 (c), the front surface bus-bar electrode 4a of solar cell element S1 and the back surface bus-bar electrode 5a of adjacent solar cell element S2 are connected by the interconnector 27, and several solar cell elements S are mutually connected. Electrically connected. In general, the interconnector 27 is made of a copper foil having a thickness of about 0.1 mm to 0.3 mm that is entirely coated with solder. The interconnector 27 and the bus bar electrode (4a, 5a) of the solar cell element S are used. The solar cell element S and the interconnector 27 are connected by soldering by heating and partially or full length or by connecting at a plurality of locations. (For example, see Patent Document 1)
Japanese Patent Laid-Open No. 11-312820

  As described above, the bus bar electrode 4 of the general solar cell element S and the interconnector 27 are connected by hot welding such as hot air or a soldering iron. Thereafter, the solar cell element S connected to the interconnector 27 is stored in a take-out cassette or the like placed at room temperature.

  As described above, when the solar cell element S is placed at room temperature immediately after the solder is melted, in the vicinity of the bus bar electrode 4 of the solar cell element S, the solar cell element S is drastically compared with the end of the solar cell element S. The temperature drops. Due to the difference in the thermal history of the solar cell element S, thermal stress concentrates in the vicinity of the bus bar electrodes 4a and 5a where the temperature change is particularly large, and the solar cell element S is warped and distorted. As a result, there is a problem that the solar cell element S is cracked, chipped, cracked or the like, and the yield of the solar cell element S is reduced.

  The present invention has been made in view of such problems, and is a reliability that improves cracking, chipping, and cracking of the solar cell element S that occurs when the solar cell element is returned to room temperature, and improves product yield. It aims at providing the manufacturing method of a high solar cell module.

  In order to achieve the above object, a method of manufacturing a solar cell module according to claim 1 of the present invention includes a bus bar electrode provided on the surface of a solar cell element for taking out output to the outside, and soldering to the bus bar electrode. A method of manufacturing a solar cell module in which an interconnector is joined via a first step of melting the solder, and the solar cell element at an ambient temperature lower than the melting temperature of the solder and higher than room temperature The second step of holding for a predetermined time.

  The method for manufacturing a solar cell module according to claim 2 of the present invention is the method for manufacturing the solar cell module according to claim 1, wherein the solder is lead-free solder.

  A method for manufacturing a solar cell module according to claim 3 of the present invention is the method for manufacturing a solar cell module according to claim 1 or 2, wherein after the solder is melted, the melting temperature of the solder is exceeded. The bus bar electrode was pressed toward the solar cell element at a low ambient temperature.

  A method for manufacturing a solar cell module according to claim 4 of the present invention is the method for manufacturing a solar cell module according to claim 3, wherein the ambient temperature of the solder is higher than room temperature.

  A method for manufacturing a solar cell module according to the present invention includes a bus bar electrode provided on the surface of a solar cell element for taking out output to the outside, and a solar cell formed by joining an interconnector to the bus bar electrode via solder. A method for manufacturing a module, comprising: a first step of melting the solder; and a second step of holding the solar cell element for a predetermined time at an atmospheric temperature lower than the melting temperature of the solder and higher than room temperature. I did it.

  As a result, the difference in the thermal history of the solar cell element can be relaxed and the thermal stress generated inside the solar cell element can be suppressed, so that cracking, chipping and cracking of the solar cell element can be prevented and the yield can be improved. it can.

  Hereinafter, the solar cell module of the present invention will be described in detail with reference to the accompanying drawings. In this specification, room temperature refers to 25 ° C.

  Fig.1 (a) is a figure which shows the structure of the cross section of the solar cell element X concerning the solar cell module Y of this invention. FIG. 9 is a diagram showing an example of the electrode shape according to the present invention, where (a) is the light receiving surface side (front surface), and (b) is the non-light receiving surface side (back surface).

  In FIGS. 1A and 9, 1 is a semiconductor substrate, 2 is a diffusion layer, 3 is an antireflection film, 4 is a surface electrode, 4a is a surface bus bar electrode, 4b is a surface finger electrode, 5 is a back electrode, and 5a is The back side bus bar electrodes, 5b are back side collecting electrodes, and 6 is a back side electric field region.

  When light is incident from the side of the antireflection film 3 that is the light receiving surface side of the solar cell element X, it is absorbed and photoelectrically converted in the bulk region of the semiconductor substrate 1 that is mainly a p-type semiconductor, and electron-hole pairs (electron carriers) And hole carriers). The surface electrode 4 provided on the light-receiving surface side (front surface) of the solar cell element X and the back electrode provided on the non-light-receiving surface side (back side) by the electron carrier and hole carrier (photogenerated carrier) originating from the photoexcitation. 5 generates a photovoltaic power. The antireflection film 3 serves to increase the amount of photogenerated carriers by reducing the reflectance in a desired light wavelength region depending on the refractive index and the film thickness of the film serving as the antireflection film. The photocurrent density Jsc is improved.

Moreover, since the back surface collecting electrode 5b of the back surface electrode 5 is normally formed using aluminum which acts as a p-type impurity element with respect to silicon which is a semiconductor substrate, p ⁺ The back surface electric field area | region 6 used as the area | region is formed. The back surface electric field region 6 is also called a BSF (Back Surface Field) region, and prevents a decrease in power generation efficiency due to recombination due to photogenerated carriers near the back surface of the semiconductor substrate 1. For this reason, photogenerated carriers generated near the back surface of the semiconductor substrate 1 are accelerated by this electric field, so that electric power is effectively extracted, and in particular, photosensitivity of a long wavelength is increased. As a result, the photocurrent density Jsc is improved, and the minority carrier (electron) density is reduced in the back surface electric field region 6, so that the diode current amount (dark current amount) in the region in contact with the back electrode 5 is reduced. As a result, the open circuit voltage Voc is improved.

  FIG. 2 shows a method for connecting solar cell elements X according to the present invention. In FIG. 2, X1 and X2 are solar cell elements, 4a is a surface bus bar electrode, 4b is a finger electrode, and 7 is an interconnector. As shown in FIG. 2, when solar cell elements provided with bus bar electrodes (4a, 5a) for taking out outputs on the light receiving surface side (front surface) and / or the non-light receiving surface side (back surface) are connected in series. The interconnector includes a bus bar electrode 4a on the light receiving surface side of the first solar cell element X1 and a bus bar electrode 5a on the non-light receiving surface side of the second solar cell element X2 arranged with a gap on substantially the same plane. 7 is electrically connected to form a solar cell module Y shown in FIG.

Next, the manufacturing process of the solar cell module Y according to the present invention will be described. First, a p-type semiconductor substrate 1 made of single crystal silicon, polycrystalline silicon, or the like is prepared. The semiconductor substrate 1 contains about 1 × 10 ¹⁶ atoms / cm ³ to 1 × 10 ¹⁸ atoms / cm ³ of one conductivity type semiconductor impurity such as boron (B), and has a specific resistance of 0.2Ω · cm to 2.0Ω. -It is a substrate of about cm. A single crystal silicon substrate is formed by a pulling method or the like, and a polycrystalline silicon substrate is formed by a casting method or the like. The polycrystalline silicon substrate can be mass-produced and is more advantageous than the single crystal silicon substrate in terms of manufacturing cost. An ingot formed by a pulling method or a casting method is cut into an appropriate size such as 10 cm × 10 cm or 15 cm × 15 cm, and sliced to a thickness of 500 μm or less, more preferably 300 μm or less to obtain a semiconductor substrate 1.

  Thereafter, a very small amount of the surface is etched with NaOH, KOH, hydrofluoric acid, or hydrofluoric acid in order to clean the cut surface of the substrate.

  Further, it is desirable to form minute protrusions on the surface on the light receiving surface side of the semiconductor substrate by using a dry etching method or a wet etching method in order to effectively take light into the substrate.

  Next, the semiconductor substrate 1 is placed in a diffusion furnace and heat-treated in a gas containing an impurity element such as phosphorus oxychloride, whereby phosphorus atoms are diffused into the surface portion of the semiconductor substrate 1 and the sheet resistance is 30Ω / A diffusion layer 2 exhibiting an n-type conductivity having a thickness of about □ to 300Ω / □ and a thickness of about 0.2 μm to 0.5 μm is formed.

  Then, the n-type diffusion layer 2 is left only on the surface side of the semiconductor substrate 1 and other portions are removed, followed by washing with pure water. The removal of the n-type diffusion layer 2 other than the surface side of the semiconductor substrate 1 is performed by, for example, applying a resist film on the surface side of the semiconductor substrate 1 and etching and removing it using a mixed solution of hydrofluoric acid and nitric acid. This is done by removing it.

  Further, an antireflection film 3 is formed on the surface side of the semiconductor substrate 1. The antireflection film 3 is made of, for example, a silicon nitride film, and is formed by, for example, a plasma CVD method in which a mixed gas of silane and ammonia is plasmatized by glow discharge decomposition and deposited. This antireflection film 3 is formed so as to have a refractive index of about 1.8 to 2.3 in consideration of a refractive index difference with respect to the semiconductor substrate 1, and is formed to a thickness of about 500 to 1000 mm. . This silicon nitride film has a passivation effect when formed, and has an effect of improving the electrical characteristics of the solar cell together with an antireflection function.

  Then, the front electrode 4 and the back electrode 5 are simultaneously formed by applying and baking a silver paste on the surface of the semiconductor substrate 1 and applying an aluminum paste and a silver paste on the back surface.

  As shown in FIG. 2A, the surface electrode 4 is composed of a surface bus bar electrode 4a for taking out an output from the surface and a surface finger electrode 4b for current collection provided so as to be orthogonal thereto. The back electrode 5 includes a back bus bar electrode 5a for extracting output from the back surface and a back current collecting electrode 5b.

  The back surface collecting electrode 5b is an aluminum paste in which aluminum powder, organic vehicle and glass frit are added in a paste form by adding 10 to 30 parts by weight and 0.1 to 5 parts by weight, respectively, with respect to 100 parts by weight of aluminum. Is baked by applying it by, for example, a screen printing method and baking it at 600 to 800 ° C. for about 1 to 30 minutes. At this time, the back surface electric field region 6 that prevents aluminum from diffusing into the semiconductor substrate 1 and recombination of carriers generated on the back surface can be formed. The back surface electric field region 6 prevents a decrease in efficiency due to recombination of photogenerated carriers near the back surface of the semiconductor substrate 1. For this reason, photogenerated carriers generated near the back surface of the semiconductor substrate 1 are accelerated by this electric field, so that electric power is effectively extracted, and in particular, photosensitivity of a long wavelength is increased. As a result, the photocurrent density Jsc is improved, and since the minority carrier (electron) density is reduced in the back surface electric field region 6, the diode current amount (dark current amount) in the region in contact with the back electrode 5 is reduced. As a result, the open circuit voltage Voc is improved.

  The front bus bar electrode 4a, the front finger electrode 4b, and the rear bus bar electrode 5a are composed of 10 parts by weight to 30 parts by weight and 0.1 parts by weight to 5 parts by weight of silver powder, organic vehicle, and glass frit, respectively, with respect to 100 parts by weight of silver. The silver paste, which is made into a paste by adding parts by weight, is baked by, for example, screen printing, drying and baking at 600 to 800 ° C. for about 1 to 30 minutes. As a coating method, a known method other than the screen printing method may be used. The surface electrode 4 may be formed by etching away a portion corresponding to the electrode of the antireflection film 3 or may be directly formed on the antireflection film 3 by a technique called fire-through.

  After the back bus bar electrode 5a for output extraction is formed, the back current collecting electrode 5b is formed so as not to cover a part of the back bus bar electrode 5a. Note that the order of forming the back surface bus bar electrode 5a and the back surface collecting electrode 5b may be reversed. Further, the back electrode 5 does not have the above-described structure, and may have a structure composed of a bus bar electrode mainly composed of silver and finger electrodes similar to the front electrode 4.

  Since the generated output is small in one solar cell element, it is necessary to combine a plurality of solar cell elements by the interconnector 7 and connect them electrically. Since the process after the connection between the interconnector and the bus bar electrode is a characteristic part of the present invention, it will be described in detail later.

  FIG. 1B shows a solar cell module Y configured by combining the solar cell elements X of FIG. FIG. 8 shows the outer shape of the solar cell module shown in FIG. X is a solar cell element, 7 is an interconnector, 8 is a translucent panel, and 22 is a frame. As shown in FIG. 8, the solar cell module according to the present invention is completed.

  As shown in FIG.1 (b), the several solar cell element X is electrically connected by the interconnector 7, and an ethylene vinyl acetate copolymer (EVA) between the translucent panel 8 and the back surface protection material 10 is shown. A solar cell module Y is configured by being hermetically sealed with a filler 9 containing, for example, a main component. The output of the solar cell module Y is connected to the terminal box 12 via the output wiring 11.

  Below, the process after the interconnector 7 connection which is the characteristic part of this invention is demonstrated in detail. First, 1st Embodiment of the manufacturing method of the solar cell module which concerns on this invention is described. FIG. 3 is a side view showing an example of the first step according to the present invention. In FIG. 3, 1 is a semiconductor substrate, 7 is an interconnector, X1 and X2 are solar cell elements, 4a and 5a are bus bar electrodes on the solar cell element, 20 is a pressing jig, and 21 is a hot air outlet.

  First, in the first step according to the present invention, after the interconnector 7 is placed on the bus bar electrodes 4a, 5a, the interconnector 7 is pressed against the bus bar electrodes 4a, 5a using the pressing jig 20. At this time, the pressing jig 20 has a function of suppressing the flapping of the interconnector by the alignment of the interconnector 7 and the hot air from the hot air discharge port 21. Then, hot air of about 400 ° C. to 500 ° C. is blown onto the solder for several seconds to melt the solder interposed between the interconnector 7 and the bus bar electrodes 4a and 5a, and then the pressing jig 20 is raised to complete the first step.

  At this time, as the interconnector 7, for example, it is preferable to use a copper foil having a thickness of about 50 μm to 400 μm cut to a predetermined length and covering the entire surface with a solder of about 20 μm to 70 μm.

  Further, the surface of the bus bar electrodes (4a, 5a) of the solar cell element X is not previously coated with solder, and the solar cell element X and the interconnector 7 are connected by melting the solder coated on the interconnector 7. You may connect.

  The temperature of the solar cell element Xp in the vicinity of the bus bar electrodes 4a, 5a of the solar cell element X immediately after the first step described above has risen to around 200 ° C. However, although the temperature rises due to hot air at the end of the solar cell element 1, the temperature is lower than that of the bus bar electrodes 4a and 5a due to heat radiation. Therefore, in order to alleviate this temperature non-uniformity, the following second step is provided.

  FIG. 4 shows an example of the second step according to the first embodiment of the present invention. In FIG. 4, solar cell elements Xp with interconnectors 15 and 15 are soldering parts, 16 is a suction pad, 17 is a conveyor belt for conveyance, 19a, 19b, 19c and 19d are heating parts (hereinafter referred to as 19a to 19d). To describe).

  As shown in FIG. 4, after passing through the first step by the soldering unit 15, the solar cell element Xp is placed on the conveyor belt conveyor 17 by the suction pad 16.

  Here, the conveyor belt conveyor 17 is composed of a belt made of metal or heat-resistant resin. In addition, heating units 19 a to 19 d are arranged below the conveyor belt conveyor 17. The heaters 19a to 19d each have a built-in heater capable of controlling the temperature, and the heaters 19a to 19d are automatically detected by a temperature sensor (not shown) such as a thermocouple disposed in the vicinity thereof. It is controlled independently to reach the set temperature. The temperature obtained by this temperature sensor was used as the ambient temperature in the present invention.

  Here, the atmospheric temperature of the solar cell element X immediately after the soldering of the interconnector 7 is finished is around 170 ° C. to 200 ° C. Therefore, it is preferable that the heating unit 19a in FIG. 3 is held for a predetermined time at an atmospheric temperature of about 140 ° C. to 150 ° C. on the conveyor belt conveyor. The heating unit 19b is preferably held for a predetermined time so that the conveying belt conveyor has an atmospheric temperature of about 110 ° C to 120 ° C. Furthermore, the heating unit 19c is held for a predetermined time so that the upper part of the conveyor belt conveyor reaches an atmospheric temperature of about 80 ° C. to 90 ° C., and the last heating unit 19d is 40 ° C. to 50 ° C. on the conveyor belt conveyor. It is preferable to hold for a predetermined time so that the ambient temperature is about 0C.

  As described above, the solar cell element Xp placed on the transfer belt conveyor 17 in the second step is lower than the temperature of the solar cell element X at the time of soldering, and is controlled to a room temperature or higher. The difference in thermal history of the solar cell element X after heat-welding the solder can be suppressed by holding the upper part of ˜19d on the conveyor belt conveyor 17 for a predetermined time. The internal stress remaining inside Xp and the warp can be alleviated and cracks caused by the internal stress can be prevented.

  Further, the total time for holding the solar cell element Xp on the above-described conveyor belt conveyor 17 is 2 to 8 times the time until the solar cell element is left at room temperature after soldering and reaches 50 ° C. Is preferred. In the case of less than 2 times, a large warp or distortion that causes a crack in the solar cell element may occur, and in the case of slow cooling over a time longer than 8 times, it takes 8 times the time. There was no significant difference in effect.

  As described above, the manufacturing method of the solar cell module Y according to the present invention is provided on the surface of the solar cell element X, and the bus bar electrodes 4a and 5a for taking out the output to the outside, and the bus bar electrodes 4a and 5a are soldered. A method of manufacturing a solar cell module in which an interconnector 7 is joined via a first step of melting the solder, and a solar cell element at an ambient temperature lower than the melting temperature of the solder and higher than room temperature. A second step of holding X for a predetermined time.

  As a result, the difference in the thermal history of the solar cell element can be relaxed and the thermal stress generated inside the solar cell element can be suppressed, so that cracking, chipping and cracking of the solar cell element can be prevented and the yield can be improved. it can.

  Note that the conveyor belt conveyor 17 may cover the solar cell upper surface portion and the side surface portion like a tunnel in order to prevent the solar cell element Xp from generating non-uniform atmosphere temperature, or the heating unit 19. The arrangement position is not limited to the lower part, and may be arranged in the upper part or the side part, or may be arranged by combining heating elements in the upper part, the lower part, or the side part. Further, the length and speed of the conveyor belt conveyor 17, the number of heating units 19, the temperature setting of each heating unit, etc., the soldering method of the interconnector 7, the solder used, the size of the solar cell element, the soldering speed, etc. The optimal value may be determined in consideration of the above.

  The solder according to the present invention is preferably lead-free solder. In recent years, Sn-Cu-Ni-based lead-free solders and Sn-Ag-Cu-based lead-free solders have been used in consideration of the environment. These lead-free solders have a melting temperature higher than that of Sn-Pb solder, and a large amount of heat is applied to the solar cell element in the first step of melting the solder. However, the present invention effectively reduces the thermal stress generated inside the solar cell element. Therefore, lead-free solder can be preferably used.

  Next, FIG. 5 shows a second embodiment according to the present invention. In FIG. 5, 7 is an interconnector, X is a solar cell element, 17 is a conveyor belt conveyor, 20 is a flooring for pressing, and 21 is a weight.

  After passing through the first step described above, the solar cell element X may be transferred to a conveyor belt conveyor 17 having a heating unit 19 shown in FIG. As shown in FIG. 5, a pressing floor plate 20 is placed on the bus bar electrodes 4a and 5a, and a weight 21 is placed on the pressing floor plate 20 at an ambient temperature lower than the melting temperature of the solder, so that the bus bar electrodes 4a and 5a are It is desirable to lower the ambient temperature of the solar cell element Xp while pressing in the direction of the battery element Xp.

  The bus bar electrodes 4a and 5a are plastically deformed by pressing the bus bar electrodes 4a and 5a toward the solar cell element while lowering the atmospheric temperature of the solar cell element Xp below the melting temperature of the solder, and the bus bar electrodes 4a and 5a Since the bonding area between the semiconductor substrate 1 and the semiconductor substrate 1 can be increased, the connection strength between the bus bar electrodes 4a and 5a and the semiconductor substrate 1 becomes strong. As a result, the reliability of the solar cell module Y can be improved.

  FIG. 6 shows another embodiment according to the present invention. In FIG. 6, Xp is a solar cell element, 7 is an interconnector, 17 is a conveyor belt conveyor, 20 is a laying board for pressing, and 21 is a weight. As shown in FIG. 6, in the manufacturing method of the solar cell module according to the present invention, it is not always necessary to press from above the interconnector, and the effect is obtained by pressing the bus bar electrodes 4a and 5a toward the semiconductor substrate 1. The effect of the present invention can be sufficiently obtained even when the interconnector 7 as often seen in small solar cell elements does not cover all the bus bar electrodes 4a and 5a. As a result, the connection strength between the bus bar electrodes 4a and 5a and the semiconductor substrate 1 is improved.

  Furthermore, in the manufacturing method of the solar cell module Y described above, it is preferable that the solder ambient temperature is higher than the room temperature when the bus bar electrodes 4a and 5a are pressed.

  In addition to the effects described above, pressing the bus bar electrodes 4a and 5a during the period from the solder melting temperature to room temperature makes the bus bar electrodes 4a and 5a more likely to be plastically deformed than pressing at room temperature or lower. The junction area between the semiconductor substrate 1 and the semiconductor substrate 1 can be further increased. As a result, the connection strength can be further improved.

  Here, the ambient temperature lower than the solder melting temperature may of course be during the above-described second step while the solar cell element X is held for a predetermined time.

  Further, the pressing floor plate 20 is for uniformly applying pressure by the weight 21 to the bus bar electrodes 4a and 5a, and is made of stainless steel, aluminum or the like so as not to adhere solder with a thickness of about 0.5 mm to 1.0 mm. Made of interconnector 7 and poor wettability material.

  The weight 21 is preferably set so that the pressure applied to the bus bar electrodes 4a and 5a is 50 g or more and 900 g or more per unit square centimeter. If it is less than 50 g, the effect of improving the connection strength of the interconnector may not occur sufficiently, and if it is less than 900 g, the semiconductor substrate itself constituting the solar cell element X may be cracked, chipped or cracked due to the unevenness of the bus bar electrode or interconnector. It is to do.

  Furthermore, the other example of the manufacturing method of the solar cell module which concerns on FIG. 7 at this invention is shown. FIG. 7A is a structural view showing a cross section, and FIG. 7B is a top view. In FIG. 7, 1 is a semiconductor substrate, 4a is a light receiving surface side bus bar electrode, 5a is a non light receiving surface side bus bar electrode, and 23 is a movable electrode pressing portion.

  As shown in FIG. 7, if an electrode pressing mechanism is provided on the conveyor belt conveyor 17, it is possible to more efficiently manufacture the solar cell element X having a high bonding strength. That is, the movable electrode pressing portion 23 has a rectangular parallelepiped pressing portion at the tip thereof, and a plurality of movable electrode pressing portions 23 are provided on both sides of the conveying belt conveyor 23. The movable electrode pressing portion 23 is moved in synchronization with the conveyor belt conveyor 23.

  In such a line, the movable electrode pressing portion 23 is normally in a position opened outward, but the solar cell element immediately after the soldering of the interconnector 7 is placed on the conveyor belt conveyor 17 is placed. Then, it is detected by a sensor or the like that the solar cell element is placed, and the movable electrode pressing portion rotates, so that the pressing portion is moved to the solar cell element with a predetermined pressure as shown in FIG. While pressing the interconnector 7 on Xp, it moves along with the movement of the conveyor belt conveyor 17. This makes it possible to automate the pressing of the bus bar electrodes 4a and 5a immediately after the soldering of the interconnector 7, and to manufacture more efficiently.

  In addition, this invention is not limited to embodiment mentioned above, Many corrections and changes can be added within the scope of the present invention. For example, the solar cell element is not limited to a crystalline solar cell such as single crystal or polycrystalline silicon, and can be applied to the above-described small solar cell element, thin film solar cell, and the like.

(A) It is a figure which shows the structure of the cross section of the solar cell element X. FIG. (B) A solar cell module Y configured by combining solar cell elements X. (C) It is the elements on larger scale of FIG.1 (b). It is a figure which shows the connection state of the solar cell element X which concerns on this invention. It is the side view which showed an example of the 1st process concerning the present invention. It is a figure showing an example of the 2nd process concerning a 1st embodiment of the present invention. It is a figure which shows 2nd Embodiment of the manufacturing method of the solar cell module which concerns on this invention. It is a figure which shows the other example of the manufacturing method of the solar cell module which concerns on this invention. It is a figure which shows the other example of the manufacturing method of the solar cell module which concerns on this invention. (A) It is a cross-section figure which shows the other example of the manufacturing method of the solar cell module which concerns on this invention. (B) It is an upper view which shows the other example of the manufacturing method of the solar cell module which concerns on this invention. It is an outline drawing of solar cell module Y concerning the present invention. It is a figure which shows an example of an electrode shape. (A) It is a figure which shows the light-receiving surface side (surface) of the solar cell element S. FIG. (B) It is a figure which shows the non-light-receiving surface side (back surface) of the solar cell element S. FIG. (A) It is a figure which shows the structure of the cross section of the general solar cell element S. FIG. (B) A conventional solar cell module T configured by combining general solar cell elements S. (C) It is the elements on larger scale of FIG.10 (b).

Explanation of symbols

1: Semiconductor substrate 2: Diffusion layer 3: Antireflection film 4: Front electrode 4a: Front bus bar electrode 4b: Front finger electrode 5: Back electrode 5a: Back bus bar electrode 5b: Back current collecting electrode 6: Back surface electric field region 7: Inter Connector 8: Translucent panel 9: Filler 10: Back surface protective material 11: Output wiring 12: Terminal box 15: Soldering part 16: Adsorption pad 17: Conveyor belt conveyor 19: Heating part 19a, 19b, 19c, 19d : Heating unit 20: pressing jig 21: hot air outlet 22: frame body 23: movable electrode pressing unit 27: conventional interconnector X, S: solar cell element Y, T: solar cell module

Claims (4)

A bus bar electrode provided on the surface of the solar cell element and for taking out the output to the outside, and a manufacturing method of a solar cell module formed by joining an interconnector to the bus bar electrode via solder,
A first step of melting the solder;
A second step of holding the solar cell element for a predetermined time at an atmospheric temperature lower than the melting temperature of the solder and higher than room temperature;
The manufacturing method of the solar cell module which has. The method for manufacturing a solar cell module according to claim 1, wherein the solder is lead-free solder. 3. The method for manufacturing a solar cell module according to claim 1, wherein after melting the solder, the bus bar electrode is pressed toward the solar cell element at an atmospheric temperature lower than the melting temperature of the solder. The method for manufacturing a solar cell module according to claim 3, wherein an ambient temperature of the solder is higher than room temperature.

Images