JP5078415B2 - Method for manufacturing solar cell and method for manufacturing solar cell module - Google Patents

Description

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

  A solar cell is a device configured by forming a PN junction made of a compound semiconductor on a substrate, and is a device that converts solar light into electricity. Therefore, in order to use solar light efficiently, generally, an antireflection film that prevents the reflection of solar light on the surface of the solar cell covers the surface of the solar cell. Formed. Moreover, the surface electrode for taking out the output of a solar cell is formed in the surface of a solar cell, and a back surface electrode is formed in a back surface at a solar cell, respectively.

  As described above, the surface electrode formed on the surface of the solar cell is used to take out the output of the solar cell. For this reason, the surface electrode connection lead wire is connected to the surface electrode. In order to connect the surface electrode connection lead wire to the surface electrode, in the conventional solar cell, the surface electrode of the solar cell is exposed to the outside without being covered with an antireflection film or the like (for example, see Patent Document 1). (See FIG. 2).

  Thus, in the conventional solar cell, the surface electrode exposed to the outside is formed on the surface of the solar cell, and the antireflection film covering the surface of the solar cell other than the surface electrode is formed Is formed.

  As a method for realizing the above configuration, the following method has been conventionally employed. First, after a surface electrode is formed on the surface of the solar cell, the surface electrode portion is covered with a photoresist by a photolithography method. Then, after the antireflection film is formed on the surface of the solar cell including the surface electrode, the photoresist is removed to expose the surface electrode. Alternatively, after forming a surface electrode on the surface of the solar cell, an antireflection film is formed on the entire surface of the solar cell. Then, a region other than the surface electrode portion is covered with a photoresist by a photolithography method, and the antireflection film on the surface electrode portion is removed by etching to expose the surface electrode.

  Conventionally, a concentrating solar cell module using the above solar cell has been proposed (see, for example, Patent Document 2). The conventional concentrating solar cell module includes, for example, a non-imaging type Fresnel lens on the opening surface of a case having an open top surface, and a solar cell held on the bottom surface of the case facing the non-imaging type Fresnel lens. A plate is provided, and the solar cell is held on the solar cell holding plate with the surface of the solar cell facing upward.

  In the concentrating solar cell module as described above, the condensing magnification is several tens to several hundred times, and the temperature of the solar cell rises due to the concentrated sunlight. Therefore, this solar cell needs to dissipate heat because the power generation efficiency decreases as the temperature rises. Therefore, a material having a high thermal conductivity such as metal is used for the solar cell holding plate used in the concentrating solar cell module, and the solar cell is bonded to the solar cell holding plate. Heat is dissipated through the backside of the.

  As a method for holding the solar cell on the solar cell holding plate, the following method is adopted in the concentrating solar cell module described in Patent Document 2. That is, first, in the concentrating solar cell module described in Patent Document 2, the functions of the back electrode and the back electrode connection lead wire are realized using metal foil. And while soldering this metal foil to the whole back surface of the board | substrate of a solar cell, this metal foil is attached to solar cell holding plates (adhesive layer) such as an epoxy resin adhesive containing a heat conductive filler ( A method of adhering to a seat plate is used.

In this method, since a very thin metal foil is used, the generation of stress due to the difference in thermal expansion coefficient between the substrate and the metal foil when the solar cell substrate and the metal foil are soldered can be reduced. At the same time, the solar cell is sufficiently radiated of heat through the metal foil, the heat dissipation layer and the seat plate, and since the epoxy resin is used for bonding, there is an advantage that durability and long-term reliability can be ensured.
JP 2002-141546 A JP 2003-174179 A

  By the way, in the conventional solar cell configured so that the surface electrode described above is exposed to the outside, an antireflection film covering the surface is formed on the surface of the solar cell, and the surface electrode exposed to the outside is provided. In order to form it, it is necessary to implement the work process using the lift-off method mentioned above and the method using an etching as a process for this.

  However, in the above operation process, in order to expose the surface electrode, a complicated operation such as photolithography or an operation for exposing the surface electrode is required, and there is a problem that the production efficiency is deteriorated. There is also a problem of a decrease in yield due to an increase in the number of work steps. Also, in this work, it is considered that the accuracy of photolithography cannot be sufficiently secured. In this case, the antireflection film is not sufficiently formed on the light receiving surface, so that the solar cell produced by the above method is converted. Efficiency may be reduced.

  Moreover, in the concentrating solar cell module of the above-described conventional example using the above solar cell, a sufficient amount of solder is used to join the metal foil to the entire back surface of the solar cell substrate, and solder bonding is performed. Sometimes, it is necessary to apply pressure to the solar cell from above and press it against the solar cell holding plate. At this time, there is a problem that the solder protrudes from the back surface of the solar cell and adheres to the side surface or the surface electrode of the solar cell due to surface tension, and a leak current flows through the solar cell when the solar cell is used. This problem is not limited to the case of using the above metal foil. In the conventional solar cell in which the back electrode is provided on the back surface, the back electrode of the solar cell is bonded to the solar cell holding plate using a conductive paste. This also occurs in the same way.

Therefore, the present invention has been made to solve such a problem, and a process involving complicated work used to expose the surface electrode formed on the surface of the solar cell is performed in the solar cell. A method for manufacturing a solar cell module that is not required for manufacturing , and a method for manufacturing a solar cell module in which leakage current does not flow into the solar cell due to manufacturing reasons when the solar cell is used. It is.

First, the manufacturing method of the solar cell of this invention is demonstrated. In the method for manufacturing a solar cell of the present invention, a main body is formed by including at least one PN junction formed by overlapping a P layer and an N layer in the front and back directions, and an end surface of the PN junction is the main body. A part of the side surface of the body part, a surface electrode on the surface of the main body part, a back electrode on the back surface, and the surface and side surfaces of the surface electrode and the surface electrode are formed. This is a method for manufacturing a solar cell , in which an antireflection film covering each of these surfaces is formed on the surface of the main body portion excluding a portion where it is present.

And in the manufacturing method of the solar cell of the above-mentioned this invention, without providing an opening in the said antireflection film which has covered the surface of the surface electrode by wire bonding or spot welding of the surface electrode connection lead wire which takes out electromotive force The antireflection film is broken, and the surface electrode and the surface electrode connection lead wire are joined .

According to the solar cell manufacturing method of the present invention described above, the surface electrode of the solar cell is covered with the antireflection film, but the surface electrode connection lead wire is connected to the surface electrode by wire bonding or spot welding. be able to. Therefore, since the surface electrode of this solar cell may be in a state covered with an antireflection film, the process for exposing the surface electrode with complicated operations as described above is not necessary when manufacturing the solar cell. It can be.

  In the above configuration, the antireflection film covering the side surface may be formed on the side surface of the surface electrode. Furthermore, in this configuration, the side surface of the surface electrode is preferably inclined so as to be narrowed from the surface of the main body portion to the surface of the surface electrode. By doing in this way, compared with the case where the side surface of the surface electrode is not inclined so as to be narrowed from the surface of the main body part to the surface of the surface electrode, the antireflection film is produced at the time of manufacturing the solar cell. Can be easily and reliably formed on the side surface of the surface electrode.

In the above solar cell manufacturing method , the antireflection film formed on the surface (and side surfaces) of the surface electrode and the surface of the main body excluding the portion where the surface electrode is formed has an insulating property. It is preferable to have it. The reason will be described later.

  In the above-described configuration, the antireflection film covering the predetermined side surface is formed on a predetermined side surface including an end surface of the PN junction part at least at a part of the side surface of the main body unit that is continuous with the surface of the main body unit. Also good. Furthermore, in this configuration, it is preferable that the predetermined side surface is inclined so as to be narrowed from the back surface to the surface of the main body portion. By doing in this way, compared with the case where the predetermined side surface is not inclined so as to be narrowed from the back surface to the front surface of the main body portion, the antireflection film is attached to the main body portion at the time of manufacturing the solar cell. It can be easily and reliably formed on a predetermined side surface.

  The antireflection film preferably has an insulating property. This is because the antireflection film covering the predetermined side surface of the main body is formed on the surface (and side surfaces) of the surface electrode of the solar cell and the surface of the main body excluding the portion where the surface electrode is formed. This is because the following functions and effects are exhibited by having an insulating property together with the antireflection film.

  In the above solar cell, the main body portion is formed by including at least one PN junction portion formed by overlapping the P layer and the N layer in the front and back directions, and the end surface of the PN junction portion is a part of the side surface of the main body portion. The predetermined side surface is formed. If an antireflection film having insulating properties is not formed on the predetermined side surface, the following situation is considered to occur.

  That is, when the solar cell in this state is used in a solar cell module described later, the solar cell is fixed to the solar cell holding plate with a conductive paste when the solar cell module is manufactured as described later. However, at this time, there is a possibility that the conductive paste combined with the back electrode of the solar cell may adhere to a predetermined side surface of the main body of the solar cell. In this case, when the conductive paste adheres to the predetermined side surface of the main body of the solar cell, the conductive paste bonded to the back electrode of the solar cell adheres to the end surface of the PN junction. When using this, there is a problem that leakage current flows through the solar cell. This problem also occurs when an antireflection film that covers the predetermined side surface is formed on the predetermined side surface of the main body of the solar cell and the antireflection film does not have insulating properties.

Further, in the above solar cell manufacturing method , when the antireflection film formed so as to cover the surface (and side surfaces) of the surface electrode of the solar cell does not have insulating properties, Similarly to the above, when used in a solar cell module described later, it is considered that the same situation as described above occurs. That is, when the solar cell module is manufactured, when the solar cell is fixed to the solar cell holding plate with the conductive paste, the conductive paste bonded to the back electrode of the solar cell adheres to the front electrode of the solar cell. There is a fear. In this case, similarly to the above, there is a problem that a leak current flows through the solar cell when the solar cell is used.

  However, as described above, the surface (and side surfaces) of the surface electrode of the solar cell, the surface of the main body portion excluding the portion where the surface electrode is formed, and the predetermined side surface of the main body portion cover these surfaces. When an antireflection film having an insulating property is formed, when manufacturing a solar cell module using this solar cell, the conductive paste for fixing the solar cell to the solar cell holding plate is the surface electrode of the solar cell. This is because leakage current can be prevented from flowing through the solar cell when the solar cell is used.

Next, the manufacturing method of the solar cell module of this invention is demonstrated. Method of manufacturing a solar cell module of the present invention, the above solar cell, the surface electrode connecting lead for taking out an electromotive force, and a method of manufacturing a solar cell module and a metal of the solar cell holding plate. In the solar cell used in this solar cell module, the main body is formed by including at least one PN junction formed by overlapping the P layer and the N layer in the front and back directions, and the PN junction The end surface of the main body portion forms a part of the side surface, the front surface electrode is formed on the surface of the main body portion, the back surface electrode is formed on the back surface, and the surface and side surfaces of the front surface electrode, and An antireflection film having insulating properties is formed on the surface and side surfaces of the main body excluding the portion where the surface electrode is formed so as to cover these surfaces. In the manufacturing method of the solar cell module of the present invention, an opening is provided in the antireflection film covering the surface of the surface electrode by wire bonding or spot welding of the surface electrode connection lead wire with respect to the solar cell. Without breaking the antireflection film, joining the surface electrode and the surface electrode connecting lead, and forming a back electrode of the solar cell between the back electrode and the solar cell holding plate By adhering to the solar cell holding plate, the solar cell is held on the solar cell holding plate.

According to the manufacturing method of the solar cell module described above, when manufacturing the solar cell module, the conductive paste for fixing the solar cell to the solar cell holding plate is the surface electrode of the solar cell or the predetermined side surface of the main body. Even when attached to the solar cell, leakage current can be prevented from flowing through the solar cell when the solar cell is used.

  In the manufacturing method of the solar cell module of the present invention, a step of forming a conductive paste layer between the back electrode of the solar cell and the solar cell holding plate, and the back electrode of the solar cell is the solar cell holding plate. Pressing the solar cell against the solar cell holding plate so as to approach the solar cell, and fixing the solar cell to the solar cell holding plate.

  That is, in this method for manufacturing a solar cell module, a conductive paste layer is formed between the back electrode of the solar cell and the solar cell holding plate, and a predetermined side surface of the main body of the solar cell from the conductive paste layer, or The solar cell holding plate is arranged so that the back electrode of the solar cell approaches the solar cell holding plate while allowing the conductive paste to protrude from the predetermined side surface of the main body of the solar cell and the surface electrode of the solar cell. And the solar cell is fixed to the solar cell holding plate.

  In this method of manufacturing a solar cell module, “allowing the protrusion of the conductive paste” means that “the protrusion of the conductive paste” may exist, and “the protrusion of the conductive paste” It does not mean that it is essential to exist.

  This method for manufacturing a solar cell module has the same effect as that described in the above solar cell module.

  In the above solar cell module manufacturing method, it is preferable that the surface electrode connection lead wire is connected to the surface electrode of the solar cell by wire bonding or spot welding. That is, in the solar cell used in this solar cell module manufacturing method, the surface electrode of the solar cell is covered with an antireflection film, but the surface electrode connection lead wire is connected to the surface electrode by wire bonding or spot welding. Can be connected to. Therefore, according to this method for manufacturing a solar cell module, the conventional solar cell which requires a process for exposing the surface electrode accompanied by complicated operations as described above is not used. Therefore, cost reduction can be achieved.

According to the method for manufacturing a solar cell of the present invention, the surface electrode of the solar cell is covered with the antireflection film, but the surface electrode connection lead wire can be connected to the surface electrode by wire bonding or spot welding. it can. Therefore, since the surface electrode of this solar cell may be in a state covered with an antireflection film, a process for exposing the surface electrode with complicated operations as described above when manufacturing this solar cell, It can be unnecessary.

  The side surface of the surface electrode is inclined so as to be narrowed from the surface of the main body portion to the surface of the surface electrode, and the predetermined side surface of the main body portion is inclined so as to be narrowed from the back surface of the main body portion to the surface. Therefore, compared with the case where it is not inclined in this way, the antireflection film can be easily and reliably formed on the side surface of the surface electrode and the predetermined side surface of the main body when the solar cell is manufactured. .

According to the method for manufacturing a solar cell module of the present invention, the solar cell used in the solar cell module excludes the surface and side surfaces of the surface electrode of the solar cell and the portion where the surface electrode is formed. On the surface of the main body part and predetermined side surfaces of the main body part, an antireflection film having insulating properties covering these surfaces is formed. Therefore, even when the conductive paste for fixing the solar cell to the solar cell holding plate adheres to the surface electrode of the solar cell or the predetermined side surface of the main body when manufacturing the solar cell module, the solar cell It is possible to prevent leakage current from flowing through the solar cell when using the above.

Further , according to the method for manufacturing a solar cell module of the present invention, the surface electrode of the solar cell used in the method for manufacturing the solar cell module is in a state covered with an antireflection film, but wire bonding or spot welding. Thus, the surface electrode connection lead wire can be connected to the surface electrode. Therefore, according to this method for manufacturing a solar cell module, the conventional solar cell which requires a process for exposing the surface electrode accompanied by complicated operations as described above is not used. Therefore, the manufacturing cost of the solar cell module can be reduced.

<Embodiment 1>
Hereinafter, a solar cell according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of solar cell 21 in the first embodiment. In FIG. 1, the solar cell 21 in Embodiment 1 is composed of a surface electrode portion 11 and a main body portion 12, and the surface and side surfaces of the surface electrode portion 11 and the surface electrode portion 11 are formed. An antireflection film 10 that covers these surfaces is formed on the surface of the main body 12 excluding the portion. That is, the surface and side surfaces of the surface electrode part 11 are all covered with the antireflection film 10, and the surface and side surfaces of the surface electrode part 11 are different from the surface electrodes in the above-described conventional solar cell. Not exposed.

  The main body 12 has a back electrode 7 formed on the back surface, which is the lower surface of the horizontally-arranged plate-like substrate 1, and the upper surface of the substrate 1 in the vertical direction, which is the front and back direction, in this order from the front surface. A base layer 2, an emitter layer 3, and a window layer 4 made of a compound semiconductor are laminated in the upward direction. Among these, the base layer 2 forms the above-described P layer, and the emitter layer 3 forms the above-described N layer, and the base layer 2 and the emitter layer 3 form a PN junction 8.

  The surface electrode portion 11 includes a contact layer 5 formed on the window layer 4 constituting the surface layer of the main body portion 12 and a surface electrode 6 formed on the contact layer 5. As for the surface electrode 6, since the surface and side surfaces of the surface electrode portion 11 are all covered with the antireflection film 10 as described above, the surface and side surfaces of the surface electrode 6 are all covered with the antireflection film 10 as well. Covered with.

  Ge, GaP, GaAs or the like is used as the material of the substrate 1 constituting the main body 12. The thickness of the substrate 1 is a thickness generally used as a substrate used for solar cells. As the substrate 1, a substrate having a pn junction formed near the substrate surface (surface on which the compound semiconductor layer is formed) may be used.

  As the material of the base layer 2, GaAs, InGaAs or the like, AlGaAs, InGaAs, InGaP, AlInGaP or the like as the material of the emitter layer 3, and InGaP, AlGaAs or the like as the material of the window layer 4 are used.

  In the solar cell 21 in the first embodiment, the layer structure composed of the compound semiconductor is a three-layer structure including the base layer 2, the emitter layer 3, and the window layer 4, but is not limited thereto. For example, a two-layer structure, a four-layer structure, or a layer structure with more layers may be used. In addition to the base layer and the emitter layer, a buffer layer, a BSF (Back Surface Field) layer, a tunnel junction layer of a multijunction photoelectric conversion element, another base layer of the multijunction photoelectric conversion element, or Other compound semiconductor layers such as an emitter layer may be included.

  The contact layer 5 constituting the surface electrode portion 11 is a compound semiconductor layer for ohmic contact formed on the uppermost layer of the compound semiconductor layer. As a material of the contact layer 5, GaAs, InGaAs or the like is used. The

  Au-Ge / Ni / Au, Ti / Pd / Ag, or the like is used as the material of the surface electrode 6 that is an ohmic electrode. Similarly, Au, Au / Ag, or the like is used as the material of the back electrode 7 that is an ohmic electrode.

As the material of the antireflection film 10, SiO, SiN, TiO ₃ / Al ₂ O ₃ or the like having high insulating properties is used. In general, ZnS, ZnS / MgF _2, or the like is also used as the material of the antireflection film 10, but these materials have lower insulating properties than the above-described materials, so that the sun in the first embodiment is used. The battery 21 is not used.

Next, a method for manufacturing solar cell 21 in the first embodiment will be described. The manufacturing method of the solar cell 21 includes Step 1 to Step 8, and the steps are sequentially performed from Step 1 to Step 8. In step 1, first, the base layer 2, the emitter layer 3, the window layer 4, and the contact layer 5 are sequentially stacked on the substrate 1 by MOCVD (metal organic chemical vapor deposition) or the like. For example, a p-type GaAs base layer 2, an n + -type GaAs emitter layer 3, an n + InGaP window layer 4 and an n + -type GaAs contact layer 5 are formed on a p + -type GaAs substrate 1 having a thickness of about 200 μm at a substrate temperature of 650 to 700. Multi-layer continuous epitaxial growth is performed at about ℃. As the source gas used at this time, TEG (trimethylgallium), TMI (trimethylindium), AsH ₃ (arsine), PH ₃ (phosphine), or the like is used. Further, SiH ₄ (monosilane) or the like is used as the n-type dopant gas, and DEZn (diethyl zinc) or the like is used as the p-type dopant gas.

  Next, in step 2, a resist is applied to the surface of the laminated compound semiconductor layer, a pattern of the surface electrode 6 is formed by photolithography, and a metal film to be the surface electrode 6 is formed thereon by vacuum deposition. To do. That is, about 100 nm of Au—Ge (12 wt%) is formed by resistance heating vapor deposition, and then about 20 nm of Ni layer and about 3000 nm of Au layer are formed by EB vapor deposition. Thereafter, the surface electrode 6 having a predetermined pattern is formed by a lift-off method.

Next, in step 3, the surface electrode 6 is sintered in an inert gas atmosphere such as N _{2 at} 300 to 450 ° C. Then, in step 4, the surface electrode 6 is masked, and the contact layer 5 where the mask is not formed is removed by etching. For this etching, an aqueous ammonia / hydrogen peroxide solution is used. As a result, the back electrode 7 is not yet formed, but the shape of the solar cell 21 in which the surface electrode portion 11 is formed on the surface of the main body portion 12 is formed.

  Next, in step 5, a mesa etching pattern is formed on the surface of the main body 12 by photolithography, and the compound semiconductor layer in the mesa etching portion is removed by etching to expose the substrate 1. A bromo-based aqueous solution is used as an etching solution for this etching. Subsequently, the mesa etching pattern formed by the above process is diced, and a predetermined cell shape is cut out.

  Next, in step 6, a back electrode 7 is formed on the back surface of the substrate 1. The back electrode 7 is formed by forming an Au layer having a thickness of about 1000 nm by EB vapor deposition.

  Next, in step 7, the antireflection film 10 having an insulating property is formed on the surface and side surfaces of the surface electrode portion 11 of the solar cell 21 and the surface of the main body portion 12 excluding the portion where the surface electrode portion 11 is formed. Form. The antireflection film 10 is formed by sequentially forming a TiO2 film and an Al2O3 film with thicknesses of about 50 nm and about 85 nm, respectively, by an EB vapor deposition method. The thickness of these films is set to an appropriate thickness in consideration of the refractive index of these films, the assumed refractive index on the surface of the solar cell 21, and the like.

  In step 8, which is the final step, finally, the back electrode 7 and the antireflection film 10 are sintered in the same procedure as in step 3 to complete the manufacture of the solar cell 21.

  In the solar cell 21 in Embodiment 1 described above, in order to extract the output from the solar cell 21, it is necessary to connect the surface electrode connection lead wire formed of aluminum, gold, or the like to the surface electrode 6 of the surface electrode portion 11. There is. As will be described later, this connection can be made by wire bonding or spot welding of the surface electrode connection lead wire on the antireflection film 10 covering the surface electrode 6. This is performed by breaking the antireflection film 10 covering the surface of the surface electrode 6 by wire bonding or spot welding and bonding the surface electrode connecting lead wire to the surface electrode 6.

  According to the solar cell 21 in the first embodiment, the surface electrode portion 11 of the solar cell 21 is covered with the antireflection film 10, but the surface electrode connection lead wire is surfaced by wire bonding or spot welding. It can be connected to the electrode 6. Accordingly, the surface electrode portion 11 of the solar cell 21 may be covered with the antireflection film 10, and therefore, in manufacturing the solar cell 21, in order to expose the surface electrode that involves complicated operations as described above. This step can be eliminated.

<Embodiment 2>
FIG. 2 is a cross-sectional view of solar cell 22 in the second embodiment. Solar cell 22 in the second embodiment is almost the same as solar cell 21 in the first embodiment. The solar cell 22 in the second embodiment is different from the solar cell 21 in the first embodiment in that a highly insulating antireflection film 10 that covers the side surface is formed on the side surface of the main body 12. The other points are exactly the same as those of solar cell 21 in the first embodiment.

  That is, an insulating antireflection film 10 covering the predetermined side surface 9 is formed on the predetermined side surface 9 including the end surface of the PN junction 8 at least at a part of the side surface of the main body unit 12 connected to the surface of the main body unit 12. Has been.

  The solar cell 22 is manufactured as follows. That is, in step 7 of the manufacturing method of solar cell 21 in Embodiment 1 described above, the main body portion excluding the surface and side surfaces of surface electrode portion 11 of solar cell 21 and the portion where surface electrode portion 11 is formed. The antireflection film 10 having an insulating property is formed on the surface of 12, and at this time, the surface of the predetermined side surface 9 including the end surface of the PN junction 8 is also insulated on at least a part of the side surface of the main body 12. The antireflection film 10 having the property is formed. Other steps are the same as the above-described manufacturing method of solar cell 21 in the first embodiment.

In the step 7, the antireflection film 10 made of TiO ₂ / Al ₂ O ₃ is formed by the EB vapor deposition method. However, SiO or SiN may be formed by the CVD method. By using this CVD method, the surface and side surfaces of the surface electrode portion 11 of the solar cell 21, the surface of the main body portion 12 excluding the portion where the surface electrode portion 11 is formed, and the side surface of the main body portion 12 At the same time, the antireflection film 10 can be formed.

  According to the solar cell 22 in the second embodiment, the following actions and effects can be obtained. That is, in the solar cell 22, as described above, the main body 12 is formed with the PN junction 8, and the end surface of the PN junction 8 is a part of the side of the main body 12. 9 is formed. In addition, an insulating anti-reflection film 10 covering the predetermined side surface 9 is formed on the predetermined side surface 9 of the main body 12, and the surface and side surfaces of the surface electrode unit 11 and the surface electrode unit 11 are On the surface of the main body portion 12 excluding the formed portion, an antireflection film 10 having insulating properties covering these surfaces is formed.

  Therefore, temporarily, the antireflection film 10 formed on the surface of the main body portion 12 excluding the predetermined side surface 9 and the surface and side surfaces of the surface electrode portion 11 and the portion where the surface electrode portion 11 is formed, If it does not have insulation, the following situation can occur.

  That is, when the solar cell 22 in this state is used in a solar cell module to be described later, the solar cell 22 is made into a solar cell holding plate by a conductive paste when the solar cell module is manufactured as described later. When bonded, the conductive paste bonded to the back electrode 7 of the solar cell 22 may adhere to the surface electrode portion 11 of the solar cell 22 or the predetermined side surface 9 of the main body portion 12 or both. . In this case, if the conductive paste bonded to the back surface electrode 7 of the solar cell 22 adheres to these portions of the solar cell 22, there is a problem that a leak current flows through the solar cell 22. The same applies to the case where the antireflection film 10 that covers the predetermined side surface 9 is not formed on the predetermined side surface 9 of the main body 12 of the solar cell 22.

  However, as described above, the surface and side surfaces of the surface electrode portion 11 of the solar cell 22, the surface of the main body portion 12 excluding the portion where the surface electrode portion 11 is formed, and the predetermined side surface of the main body portion 12. 9, when the antireflection film 10 having an insulating property covering these surfaces is formed, the conductive paste for bonding the solar cell 22 is formed on the surface of the solar cell 22 when the solar cell module is manufactured. Even if it adheres to the electrode part 11 or the predetermined side surface 9 of the main body part 12, it is possible to prevent leakage current from flowing through the solar cell 22.

  In the solar cell 22 in the second embodiment, at least a part of the side surface of the main body portion 12 that is continuous with the surface of the main body portion 12 among the side surfaces of the main body portion 12, the predetermined side surface including the end surface of the PN junction portion 8. An insulating antireflection film 10 that covers the predetermined side surface 9 is formed only on 9. However, the present invention is not limited to this, and an antireflection film 10 having an insulating property that covers the entire side surface of the main body 12 may be formed on the entire side surface of the main body 12.

<Embodiment 3>
FIG. 3 is a cross-sectional view of solar cell 23 in the third embodiment. Solar cell 23 in the third embodiment is almost the same as solar cell 22 in the second embodiment. The solar cell 23 in the third embodiment is different from the solar cell 22 in the second embodiment only in the shape of the surface electrode portion 11, and the other points are exactly the same as the solar cell 22 in the second embodiment. It is. That is, in FIG. 3, in the surface electrode part 11 of the solar cell 23 in Embodiment 3, the side surface of the surface electrode 6 of the surface electrode part 11 is narrowed from the surface of the main body part 12 to the surface of the surface electrode 6. Inclined.

The solar cell 23 is manufactured as follows. In step 2 of the manufacturing method of solar cell 22 in Embodiment 2, that is, in step 2 of manufacturing method of solar cell 21 in Embodiment 1, surface electrode 6 is formed by the lift-off method. Change to the following method. That is, Au—Ge / Ni / Au is formed on the surface of the compound semiconductor layer laminated in Step 1, and then an electrode pattern is formed on the metal film by photolithography, and a metal such as a KI / I ₂ solution is formed. The surface electrode 6 is formed by etching with an etching solution. By this method, the side surface of the surface electrode 6 can be inclined so as to be narrowed from the surface of the main body portion 12 to the surface of the surface electrode 6. Other steps are the same as the manufacturing method of solar cell 22 in the second embodiment.

  According to the solar cell 23 in the third embodiment, the side surface of the surface electrode 6 is inclined so as to be narrowed from the surface of the main body portion 12 to the surface of the surface electrode 6. Compared with the case where it is not, when manufacturing the solar cell 23, the antireflection film 10 can be easily and reliably formed on the side surface of the surface electrode 6, that is, the side surface of the surface electrode portion 11. Moreover, since the coverage of the antireflection film 10 covering the surface electrode 6 is improved when the side surface of the surface electrode 6 is inclined as described above, a higher prevention effect against the leakage current of the solar cell 23 is obtained. Can be obtained.

<Embodiment 4>
FIG. 4 is a cross-sectional view of solar cell 24 in the fourth embodiment. Solar cell 24 in the fourth embodiment is almost the same as solar cell 23 in the third embodiment. The solar cell 24 in the fourth embodiment is different from the solar cell 23 in the third embodiment only in the shape of the side surface of the main body 12, and the other points are completely different from those in the solar cell 23 in the third embodiment. The same.

  That is, in FIG. 4, the shape of the side surface of the main body portion 12 of the solar cell 24 in Embodiment 4 is at least a part of the side surface of the main body portion 12 that is continuous with the surface of the main body portion 12. The predetermined side surface 9 is inclined so as to be narrowed from the back surface to the front surface of the main body 12.

  The solar cell 24 is manufactured as follows. In step 1 of the manufacturing method of solar cell 23 in Embodiment 3, that is, in step 5 of manufacturing method of solar cell 21 in Embodiment 1, an aqueous hydrochloric acid solution and an aqueous ammonia / hydrogen peroxide solution are used as the etching solution. And etching. Other steps are the same as those of the manufacturing method of the solar cell 23 described in the third embodiment.

  According to the solar cell 24 in the above-described fourth embodiment, the predetermined side surface 9 including the end surface of the PN junction portion 8 at least part of the side surface of the main body portion 12 connected to the surface of the main body portion 12 is Since the shape is inclined so as to be constricted from the back surface to the front surface, the antireflection film 10 is applied to the predetermined side surface 9 of the main body 12 when the solar cell 24 is manufactured as compared with the case where the shape is not such. It can be formed easily and reliably.

  In the solar cell 24 according to the fourth embodiment, at least a part of the side surface of the main body 12 connected to the surface of the main body 12 among the side surfaces of the main body 12, the predetermined side including the end surface of the PN junction 8. An insulating antireflection film 10 that covers the predetermined side surface 9 is formed only on 9. However, the present invention is not limited to this, and as shown in FIG. 5, an insulating antireflection film 10 covering the entire surface of the side surface of the main body 12 may be formed.

<Embodiment 5>
6 is a cross-sectional view of a solar cell module 31 using the solar cell 24 in the above-described fourth embodiment, and FIG. 7 is an enlarged cross-sectional view of the solar cell module 31 in which the solar cell 24 is attached. 6 and 7, the solar cell module 31 according to the fifth embodiment is not shown in the solar cell 24, the case 32, the Fresnel lens 33, the surface electrode connection lead wire 34, the solar cell holding plate 35, and the like. It consists of a back electrode connection lead wire.

  The case 32 is a hollow case having a rectangular cross section and an opening surface on the upper surface, and a non-imaging Fresnel lens 33 is attached to the opening surface of the case 32. On the inner bottom surface of the solar cell holding plate support portion 32a, which is the bottom of the case 32, a metal solar cell holding plate 35 is fixed with an adhesive 37 having thermal conductivity and insulation. The solar cell 24 is fixed to the upper surface of the solar cell holding plate 35 with a conductive paste 36 so that the back electrode 7 of the solar cell 24 faces the solar cell holding plate 35. And the surface electrode connection lead wire 34 is the surface electrode 6 of the surface electrode part 11 of the solar cell 24 (specifically, the terminal which joins the surface electrode connection lead wire 34 provided in the surface electrode 6 by wire bonding or spot welding) A back electrode connection lead wire (not shown) is connected to the solar cell holding plate 35 at the mounting portion (see the bonding position of the front electrode 6 to the front electrode connection lead wire 34 shown in FIG. 7).

  As described above, the solar cell 24 used in the solar cell module 31 excludes the surface and side surfaces of the surface electrode portion 11 of the solar cell 24 and the portion where the surface electrode portion 11 is formed. On the surface of the main body 12 and the predetermined side surface 9 of the main body 12, an antireflection film 10 having an insulating property covering these surfaces is formed.

  As the material of the case 32, aluminum that is lightweight and has good thermal conductivity is suitable. However, a stainless steel plate, a steel plate, or a steel plate plated with zinc, aluminum, silicon, or the like may be used.

  As a material of the Fresnel lens 33, a translucent material such as acrylic resin, polycarbonate, UV curable resin, or glass is used. The sunlight condensing magnification of the Fresnel lens 33 is about 700 times at maximum. As shown by a dotted line in FIG. 6, the sunlight 38 is collected by the Fresnel lens 33 and irradiated as the irradiation light 39 to the solar cell 24 fixed on the upper surface of the solar cell holding plate 35.

  As a material of the solar cell holding plate 35, a material mainly made of a metal or alloy having a high thermal conductivity is used. For example, simple metals such as gold, silver, copper, aluminum, magnesium, iron, nickel, tin, and stainless steel, alloys thereof, and the like.

  As a material of the adhesive 37 having thermal conductivity and insulation used for fixing the solar cell holding plate 35 to the solar cell holding plate support portion 32a, a main agent such as epoxy resin, silicon resin, etc., and gold as an additive are used. A mixture of one or more metals such as silver, copper, aluminum, magnesium, iron, and stainless steel, metal oxides such as aluminum oxide, magnesium oxide, and zinc oxide, boron nitride, aluminum nitride, and carbon is used. .

  Examples of the conductive paste 36 having a high thermal conductivity used for fixing the solar cell element 24 on the solar cell holding plate 35 include gold, silver, copper, aluminum, magnesium, iron, nickel, and tin. In addition, a material containing one or more of metals such as stainless steel or carbon in an organic material or the like, or solder is used. As a fixing method, a method of firing or brazing the conductive paste 36 is used.

  As the material of the surface electrode connection lead wire 34, aluminum, gold or the like is used. As a connection method, favorable conduction is obtained between the surface electrode 6 (terminal mounting portion) and the surface electrode connection lead wire 34 by bonding by wire bonding, which is preferable. In addition, a silver foil or the like may be used as the surface electrode connection lead wire 34 and the silver foil or the like may be spot welded.

  According to the solar cell module 31 in the fifth embodiment, the solar cell 24 used in the solar cell module 31 has the surface of the surface electrode 6 of the surface electrode portion 11 of the solar cell 24 as described above. And an antireflection film 10 having insulating properties covering these surfaces is formed on the surface of the main body portion 12 excluding the portion where the surface electrode portion 11 is formed, and on the predetermined side surface 9 of the main body portion 12. Has been. Accordingly, when the solar cell module 31 is manufactured, even if the conductive paste 36 for adhering the solar cell 24 adheres to the surface electrode 6 of the solar cell 24 or the predetermined side surface 9 of the main body 12, It is possible to prevent leakage current from flowing through the solar cell 24 when the battery 24 is used.

  Next, the manufacturing method of the solar cell module 31 in Embodiment 5 will be described. First, the solar cell holding plate 35 is fixed to the solar cell holding plate support portion 32a of the case 32 with an adhesive 37 having thermal conductivity and insulation. The solar cell 24 is fixed to the upper surface of the fixed solar cell holding plate 35 by using a conductive paste 36 having a high thermal conductivity.

  For fixing the solar cell 24 to the upper surface of the solar cell holding plate 35, first, a conductive paste layer made of the conductive paste 36 is provided between the back electrode 7, which is the back surface of the solar cell 24, and the solar cell holding plate 35. Form. Then, the conductive paste from the conductive paste layer to the predetermined side surface 9 of the main body portion 12 of the solar cell 24 or the predetermined side surface 9 of the main body portion 12 of the solar cell 24 and the surface electrode portion 11 of the solar cell 24. The solar cell 24 is pressed against the solar cell holding plate 35 so that the back electrode 7 of the solar cell 24 approaches the solar cell holding plate 35 while allowing the protrusion 36 to protrude, and the solar cell 24 is moved to the solar cell holding plate 35. It sticks to.

  Then, the surface electrode connection lead wire 34 is connected to the surface electrode 6 (terminal mounting portion) of the solar cell 24 by wire bonding or spot welding. Further, the back electrode connection lead wire is connected to the solar cell holding plate 35, and the front electrode connection lead wire 34 and the back electrode connection lead wire are pulled out of the case 32. Then, the Fresnel lens 33 is attached to the opening surface of the case 32.

  In the method for manufacturing the solar cell module 31 described above, “while allowing the conductive paste 36 to protrude” means that “the protrusion of the conductive paste 36” may exist. It does not mean that the presence of the “protrusion of the conductive paste 36” exists.

  According to the manufacturing method of the solar cell module 31 described above, the solar cell 24 used in the manufacturing method has the surface and side surfaces of the surface electrode portion 11 of the solar cell 24 and the surface electrode portion 11 formed therein. An antireflection film 10 having an insulating property covering these surfaces is formed on the surface of the main body 12 excluding the portion and the predetermined side surface 9 of the main body 12. Therefore, when manufacturing the solar cell module 31, even if the conductive paste 36 that adheres the solar cell 24 adheres to the surface electrode portion 11 of the solar cell 24 or the predetermined side surface 9 of the main body portion 12, A solar cell 24 that can prevent leakage current from flowing through the solar cell 24 when the battery 24 is used can be manufactured.

  In the method for manufacturing the solar cell module 31, the surface electrode 6 of the solar cell 24 used in the method for manufacturing the solar cell module 31 is covered with the antireflection film 10, but wire bonding or spot welding is used. Thus, the surface electrode connection lead wire 34 can be connected to the surface electrode 6. Therefore, according to the method for manufacturing the solar cell module 31, the conventional and costly solar cell that requires a process for exposing the surface electrode with complicated operations as described above is used. Therefore, the manufacturing cost of the solar cell module 31 can be reduced.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  This application claims priority based on Japanese Patent Application No. 2006-112409 filed in Japan on April 14, 2006. By this reference, the entire contents thereof are incorporated into the present application.

The present invention can be used in a method for manufacturing a solar cell and a method for manufacturing a solar cell module .

FIG. 1 is a cross-sectional view of the solar cell in the first embodiment. FIG. 2 is a cross-sectional view of the solar cell in the second embodiment. FIG. 3 is a cross-sectional view of the solar cell in the third embodiment. FIG. 4 is a cross-sectional view of the solar cell in the fourth embodiment. FIG. 5 is a cross-sectional view of another example solar cell in the fourth embodiment. FIG. 6 is a cross-sectional view of the solar cell module according to Embodiment 5. FIG. 7 is an enlarged cross-sectional view of the solar cell mounting portion of the solar cell module according to the fifth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Base layer 3 Emitter layer 4 Window layer 5 Contact layer 6 Front surface electrode 7 Back surface electrode 8 PN junction part 9 Predetermined side surface 10 Antireflection film 11 Front surface electrode part 12 Main body part 21 Solar cell 22 Solar cell 23 Solar cell 24 Solar cell 31 Solar cell module 32 Case 32a Solar cell holding plate support 33 Fresnel lens 34 Surface electrode connection lead 35 Solar cell holding plate 36 Conductive paste 37 Adhesive 38 Sunlight 39 Irradiation light

Claims (8)

The main body is formed with at least one PN junction formed by overlapping the P layer and the N layer in the front and back directions, and the end surface of the PN junction forms a part of the side of the main body. In addition, the front surface electrode is formed on the front surface of the main body portion, the back surface electrode is formed on the back surface, and the front and side surfaces of the front surface electrode, and the main body portion excluding the portion where the front surface electrode is formed. A method for manufacturing a solar cell in which an antireflection film covering each of these surfaces is formed on the surface,
Breaking the antireflection film without providing an opening in the antireflection film covering the surface of the surface electrode by wire bonding or spot welding of the surface electrode connection lead wire for extracting the electromotive force, the surface electrode and the surface electrode A method of manufacturing a solar cell, comprising joining a connecting lead wire . 2. The method for manufacturing a solar cell according to claim 1, wherein a side surface of the surface electrode is inclined so as to be narrowed from a surface of the main body portion to a surface of the surface electrode. The antireflection film for covering the predetermined side surface is formed on a predetermined side surface including an end surface of the PN junction part in at least a part of the side surface of the main body unit continuous with the surface of the main body unit. The manufacturing method of the solar cell of 1 or 2. The method for manufacturing a solar cell according to claim 3, wherein the predetermined side surface is inclined so as to be narrowed from a back surface to a front surface of the main body portion. The method for manufacturing a solar cell according to claim 1, wherein the antireflection film has an insulating property. A solar cell holding plate made of metal, a surface electrode connection lead wire for taking out an electromotive force , and a solar cell , wherein the solar cell has at least one PN junction formed by overlapping a P layer and an N layer in the front and back direction. A body part is formed, and an end surface of the PN junction part forms a part of a side surface of the body part, and a surface electrode is formed on the surface of the body part, and a back electrode is formed on the back surface. In addition, an antireflection film having an insulating property covers each of the surfaces and side surfaces of the main body portion excluding the surface and side surfaces of the surface electrode, and the portion where the surface electrode is formed. A method for manufacturing a formed solar cell module , comprising:
With respect to the solar cell, the surface electrode is broken by wire bonding or spot welding of the surface electrode connection lead without providing an opening in the antireflection film covering the surface of the surface electrode. And the surface electrode connection lead wire,
The back electrode of the solar cell is fixed to the solar cell holding plate by a conductive paste layer formed between the back electrode and the solar cell holding plate, and the solar cell is held on the solar cell holding plate. The manufacturing method of the solar cell module characterized by the above-mentioned . It is a manufacturing method of the solar cell module according to claim 6,
Forming a conductive paste layer between the back electrode of the solar cell and the solar cell holding plate;
Pressing the solar cell against the solar cell holding plate so that the back electrode of the solar cell approaches the solar cell holding plate, and fixing the solar cell to the solar cell holding plate. A method for producing a solar cell module. It is a manufacturing method of the solar cell module according to claim 7,
A conductive paste layer is formed between the back electrode of the solar cell and the solar cell holding plate, and the side surface of the solar cell from the conductive paste layer, or the side surface of the solar cell and the surface of the solar cell. The solar cell is pressed against the solar cell holding plate so that the back electrode of the solar cell approaches the solar cell holding plate while allowing the conductive paste to protrude over the electrode, and the solar cell is moved to the solar cell. A method for manufacturing a solar cell module, wherein the solar cell module is fixed to a battery holding plate.

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