JP6011626B2 - Solar cell module - Google Patents

Description

The present invention relates to a solar cell element and a solar cell module.

  A solar cell element is well known in which a thin paste electrode is formed by printing a metal paste on the surface of a semiconductor substrate such as crystalline silicon. For example, Patent Document 1 discloses a method of forming a thick collector electrode by repeating printing of a metal paste a plurality of times in order to reduce the resistance of the collector electrode.

  As a solar cell module, a structure in which a solar cell element is sealed with a transparent sealing resin between a glass plate and a back surface sealing material is well known. A typical sealing method is to sandwich a plurality of solar cell elements that are electrically connected to each other with a conductive wire between a glass plate and a sealing sheet that is a back surface sealing material, and provide a gap between the glass plate and the sealing sheet. This is a method of filling with a sealing resin such as EVA (ethylene vinyl acetate copolymer resin) that is heated and melted. In order to avoid damage to the solar cell element during the sealing process, for example, Patent Document 2 discloses a method of sealing by placing a thick sealing resin sheet piece in the gap between the solar cell elements. Since the pressure at the time of the sealing process is applied to the thick sealing resin sheet piece and is not directly applied to the solar cell element, damage to the solar cell element is prevented.

JP 2007-243230 A International Publication No. 2004/038811

  When the collector electrode is formed thick as in Patent Document 1, the electrode protrudes from the surface of the semiconductor substrate, which causes a problem that the collector electrode collides with an object and is damaged. In addition, when a collision occurs, a local force is applied to the semiconductor substrate via the collector electrode, causing a problem that the semiconductor substrate is cracked or broken. Further, even during the sealing process of the solar cell module, there is a problem that the surface of the solar cell element is in contact with a hard glass plate, the electrode is damaged, and the semiconductor substrate is cracked. Such a problem is difficult to prevent even with the configuration of Patent Document 2.

  In view of the above, an object of the present invention is to realize a solar cell element and a solar cell module that can prevent the collector electrode from being damaged and are unlikely to crack in the semiconductor substrate.

The solar cell module of the present invention includes a semiconductor substrate having a photovoltaic joint , a plurality of collector electrodes formed on the first surface of the semiconductor substrate and arranged in parallel with each other at a constant interval, and a first semiconductor substrate. A back electrode formed on the second surface, which is the back surface of one surface, and a concave portion that covers the collector electrode at a position facing each collector electrode, and is connected to the collector electrode in the recess and is electrically connected A transparent resin plate having a first connection region at a position protruding from the end of the semiconductor substrate, and a back electrode at a position facing the back electrode. A concave portion is formed, and a second conductive member that is connected to and conductively connected to the back electrode is formed in the concave portion. The second conductive member is disposed so as to cover the back electrode and the second surface, and is located at a position protruding from the end of the semiconductor substrate. A back surface resin plate having two connection areas; Solar cell modules in which solar cell elements connected in series are arranged in series, and the first connection region and the second connection region of adjacent solar cell elements are overlapped and connected via a conductive connection part The collector electrode of one solar cell element and the back electrode of the other solar cell element are electrically connected between adjacent solar cell elements.

The solar cell element according to the solar cell module of the present invention includes a semiconductor substrate having a collector electrode formed on the surface thereof, and a transparent resin plate bonded with a transparent adhesive so as to cover the collector electrode and the surface of the semiconductor substrate. Since the concave portion is formed in the transparent resin plate at a position facing the collector electrode, the collector electrode can be prevented from being damaged. Moreover, since the bonded transparent resin plate mechanically reinforces the semiconductor substrate, cracks are unlikely to occur in the semiconductor substrate.

  According to the solar cell module of the present invention, the solar cell element is a solar cell module fixed with a transparent sealing resin between a glass plate and a sealing material, and the transparent resin plate is the semiconductor substrate. Since it is arranged closer to the glass plate than the collector electrode, the collector electrode is not in direct contact with the glass plate even when a sealing resin having high fluidity is used for sealing, and the collector electrode can be prevented from being damaged. Cracks are unlikely to occur on the substrate.

4 is a top view showing the structure of the solar cell module according to Embodiment 1. FIG. 2 is a cross-sectional view showing the structure of the solar cell module according to Embodiment 1. FIG. It is the perspective view which looked at the solar cell element of Embodiment 1 from the front side. 3 is a partial cross-sectional view of the solar cell module according to Embodiment 1. FIG. It is a fragmentary sectional view explaining the manufacturing method of the solar cell module of this Embodiment 1. FIG. It is a fragmentary sectional view explaining the manufacturing method of the solar cell module of this Embodiment 1. FIG. It is a fragmentary sectional view explaining the manufacturing method of the solar cell module of this Embodiment 1. FIG. It is a fragmentary sectional view explaining the manufacturing method of the solar cell module of this Embodiment 1. FIG. It is a fragmentary sectional view explaining the manufacturing method of the solar cell module of this Embodiment 1. FIG. It is a partial side view explaining the manufacturing method of the solar cell module of this Embodiment 1. FIG. It is a partial side view explaining the manufacturing method of the solar cell module of this Embodiment 1. FIG. It is a partial side view explaining the manufacturing method of the solar cell module of this Embodiment 1. FIG. 6 is a partial cross-sectional view of the solar cell module according to Embodiment 2. FIG. 6 is a partial cross-sectional view of the solar cell module according to Embodiment 3. FIG. 6 is a partial cross-sectional view of a solar cell module according to Embodiment 4. FIG. 6 is a partial cross-sectional view of a solar cell module according to Embodiment 5. FIG. 6 is a cross-sectional view illustrating an example of a light incident path of the solar cell module according to Embodiment 5. FIG. FIG. 10 is a cross-sectional view illustrating another example of the light incident path of the solar cell module according to the fifth embodiment. FIG. 10 is a partial cross-sectional view of a solar cell module according to a sixth embodiment. It is the top view which showed the semiconductor substrate of the solar cell element of Embodiment 6, and the front side collector electrode on it. FIG. 10 is a top view showing a transparent resin plate of a solar cell element in a sixth embodiment. FIG. 10 is a perspective view showing an example of a solar cell element in a sixth embodiment. 10 is a partial cross-sectional view showing an example of a connection structure of solar cell elements of a solar cell module according to Embodiment 6. FIG. FIG. 10 is a partial cross-sectional view of a solar cell module according to a seventh embodiment.

  Embodiments of a solar cell element and a solar cell module of the present invention will be described below with reference to the drawings. In the figure, components are denoted by reference numerals, and description of the components denoted by the same reference numerals is omitted.

Embodiment 1 FIG.
FIG. 1 is a top view showing an example of the structure of the solar cell module according to the first embodiment. FIG. 1 is a view seen from the front (front) side which is the light receiving surface side of sunlight. FIG. 2 is a cross-sectional view showing the structure of the solar cell module according to Embodiment 1, and is a cross section taken along the dotted line AB in FIG. This solar cell module is a solar cell module 100 in which a solar cell element 30 is sealed with a sealing resin 16 between a glass plate 11 and a sealing material 12. The solar cell elements 30 are provided with collector electrodes on the front surface and the back surface, and the electrodes of the adjacent solar cell elements 30 arranged in series are interconnected by an interconnector 21. Although FIG. 1 is a diagram in which twelve solar cell elements 30 are connected in series, the number and arrangement can be arbitrarily changed, and parallel connection may be combined. Although not shown in the drawing, lead wires for taking out electric power are connected to both ends of the solar cell module 100 connected in series.

  The glass plate 11 can use materials, such as soda-lime glass, for example. In the solar cell module used outdoors, the glass plate 11 may be heat strengthened or chemically strengthened. Although the size of the glass plate 11 can be variously changed according to the number of the solar cell elements 30, a typical thickness is 0.5 to 3 mm or the like. As the sealing material 12, a film having low moisture permeability or a glass plate similar to the front side is used so that the solar cell element is not deteriorated due to intrusion of moisture or the like. In order to reflect the solar cell element 30 and the light that has passed through the gap between the solar cell element 30 and the solar cell element 30, a white or metallic light reflective material may be used as the sealing material 12. As the sealing resin 16, transparent EVA, silicone resin, or the like can be used. For the interconnector 21, for example, a copper wire coated with solder can be used.

  FIG. 3 is a perspective view of the solar cell element 30 of the first embodiment viewed from the front side. This figure shows a diagram in which the interconnector 21 is connected to the solar cell element 30. The solar cell element 30 includes a semiconductor substrate 1 on which the front side collector electrode 2 is formed, and a transparent resin plate 5 bonded so as to cover the surface of the semiconductor substrate 1 on which the front side collector electrode 2 and the front side collector electrode 2 are not formed. Have. The transparent resin plate 5 is bonded onto the semiconductor substrate 1 with a transparent adhesive. Although the front side collector electrode 2 has a continuous thin line shape, in the figure, the front side collector electrode 2 is covered with the transparent resin plate 5 and is therefore indicated by a dotted line. In the solar cell module, the transparent resin plate 5 is disposed closer to the glass plate than the semiconductor substrate.

The transparent resin plate 5 has the same area as the semiconductor substrate 1 and covers almost the entire surface of the semiconductor substrate 1.
It is desirable that the outer shape of the transparent resin plate 5 be a shape substantially along the semiconductor substrate 1. The transparent resin plate 5 may protrude from the semiconductor substrate 1, but when used in the solar cell module 100, the transparent resin plate 5 of the solar cell element 30 does not overlap the semiconductor substrate 1 of the adjacent solar cell element 30. It is recommended that the amount of protrusion be small. Further, as shown in the figure, the transparent resin plate 5 may not be formed in a region to which the interconnector 21 is connected. When the interconnector 21 is connected so as to divide the surface of the semiconductor substrate 1, the transparent resin plate 5 may be divided into a plurality of parts.

  A concave portion 5 h is formed in the transparent resin plate 5 at a position facing the front-side collector electrode 2. Since the front-side collector electrode 2 is formed on the surface on the light-receiving surface side, it is formed in a fine line pattern so as not to block light incident on the semiconductor substrate 1 as much as possible. The front-side collector electrode 2 is formed by screen printing of a metal paste or the like and protrudes from the surface of the semiconductor substrate 1. The recess 5 h is formed in a shape that covers the protruding front collector electrode 2. That is, the transparent resin plate 5 is formed with a groove having substantially the same shape as the front collector 2 on the side facing the surface of the semiconductor substrate 1 and is combined with each other so that the front collector 2 is located in the recess 5h. It is in. The thickness of the transparent resin plate 5 may be smaller than that of the interconnector 21, but is preferably equal to or greater. Further, the transparent resin plate 5 may be thicker than the semiconductor substrate 1.

  The semiconductor substrate 1 is a thin semiconductor substrate made of crystalline silicon such as single crystal silicon or polycrystalline silicon, a compound semiconductor, or the like. In the case of crystalline silicon, the typical substrate size is approximately 10 to 15 cm square, and the thickness is 0.1 to 0.3 mm.

  FIG. 4 is a partial cross-sectional view of the solar cell module 100 in which the solar cell element 30 of the first embodiment is sandwiched between the glass plate 11 and the sealing material 12 on the back surface side, and a cross section that crosses the front-side collector electrode 2. Is shown. The solar cell element 30 is sandwiched between the glass plate 11 on the front side and the sealing material 12 on the back side, and is covered and fixed with transparent sealing resins 16a and 16b. The sealing resin 16a and the sealing resin 16b are a front side portion and a back side portion of the sealing resin 16 (see FIG. 2).

  A semiconductor layer containing impurities having a conductivity type opposite to that of the semiconductor substrate 1 is formed on the front side or the back side of the semiconductor substrate 1. A semiconductor layer containing impurities of the same conductivity type as that of the semiconductor substrate 1 is formed on the opposite surface. Electrodes are formed on these semiconductor layers, respectively, and current is taken out. The front side collecting electrode 2 is a thin line-like electrode formed on the front side surface, which is the main light receiving surface of the solar cell element 30, as such an electrode. The front-side collector electrode 2 is an electrode that collects current generated in the semiconductor substrate surface and guides it to the interconnector 21. The front-side collecting electrode 2 is preferably a grid-like pattern in which thin lines extending in a straight line are arranged in parallel at intervals as shown in the figure, but may be a mesh pattern or a dendritic pattern. The front-side collector electrode 2 is sometimes called a grid electrode or a finger electrode because of its shape.

  As shown in the figure, the semiconductor substrate 1 of the solar cell element 30 has fine irregularities for preventing reflection on the front side. Although the back side of the semiconductor substrate 1 is flat in the figure, fine irregularities may be formed on the back side, and both sides may be flat.

  The front-side collector electrode 2 is formed by printing a metal paste in which metal fine particles such as silver or copper and a resin are mixed on the front-side surface of the semiconductor substrate 1 and baking it by heating. The front-side collector electrode 2 thus formed protrudes from the main surface of the semiconductor substrate 1. When the width of the front-side collector electrode 2 is increased, the light receiving area is reduced. When the thickness is thin, the cross-sectional area is reduced and the loss is increased due to an increase in electric resistance. For this reason, it is desirable that the front collector electrode 2 has a narrow cross-sectional shape whose height is increased by increasing the thickness. A typical front side collector electrode 2 has a width of 0.04 to 0.1 mm and a height of 0.02 to 0.05 mm, and the interval between adjacent front side collector electrodes 2 is 1 to 4 mm. A transparent conductive film may be formed between the front-side collector electrode 2 and the semiconductor substrate 1.

  A back side collector electrode 3 is formed on the back side of the semiconductor substrate 1. The back side collector electrode 3 is an electrode whose positive and negative are opposite to those of the front side collector electrode 2. Similarly to the front-side collector electrode 2, it can be formed by printing a metal paste or the like, and can also be formed by a film forming technique such as a vapor deposition method or a sputtering method, or a plating method. In the figure, the back side collector electrode 3 is formed on the entire back surface, but may have a pattern shape made of fine lines as in the light receiving surface side.

  The transparent resin plate 5 is bonded by a transparent adhesive 9 so as to cover the surface of the semiconductor substrate 1 in a region where the front side collector electrode 2 is not formed and the front side collector electrode 2. The transparent resin plate 5 has a recess 5h formed at a position facing the front-side collector electrode 2, but all or most of the recess 5h is a flat surface. The height of fine irregularities on the front surface of the semiconductor substrate 1 is about several μm, which is sufficiently small when viewed from the height of the front collector 2. For this reason, the front side surface of the semiconductor substrate 1 is a substantially flat surface. Further, the surface of the transparent resin plate 5 between the recesses 5h is flat. Therefore, the transparent resin plate 5 and the semiconductor substrate 1 are bonded to each other by a thin layer of adhesive 9 between these relatively flat surfaces. The thickness of the adhesive 9 is thinner than the height of the front collector electrode 2. If there are fine irregularities on the surface of the semiconductor substrate 1, the thickness may be such that the irregularities are filled flat. With such a configuration, the transparent resin plate 5 and the semiconductor substrate 1 are firmly bonded to each other by a thin adhesive 9 between flat surfaces.

  Further, the width of the opening of the recess 5 h of the transparent resin plate 5 is made wider than the width of the front-side collector electrode 2. Further, the depth of the recess 5h is preferably equal to or greater than the height of the front collector electrode 2. If it does in this way, a clearance gap will be formed between the front side collector electrode 2 and the recessed part 5h, and it will become a structure where the adhesive agent 9 penetrates into this clearance gap. In addition, although the figure showed the case where the front side collector electrode 2 and the recessed part 5h did not contact, you may contact partially.

  Since the material of the transparent resin plate 5 is installed on the front side which is the main light receiving surface, a material with high transparency is desirable. Further, a material having a higher heat resistant temperature than the sealing resin 16 is desirable. In addition, this heat-resistant temperature is a temperature which can hold | maintain a shape, For example, load deflection temperature, Vicat softening temperature, glass transition temperature etc. can be considered as heat-resistant temperature. For example, when considering EVA as a typical sealing resin 16, the deflection temperature under load (0.45 MPa) is about 30 ° C., so that the deflection temperature under load is about 70 ° C. PET (polyethylene terephthalate), PEN about 110 ° C. (Polyethylene naphthalate), COP (cycloolefin polymer) of 120 to 150 ° C. or the like can be used as the material of the transparent resin plate 5. Thus, it is desirable that the deflection temperature under load is 40 ° C. or more higher than the deflection temperature under load of the sealing resin 16.

  The material of the transparent resin plate 5 is preferably a material having a small optical refractive index difference from the sealing resin 16 and the adhesive 9. For example, among the optical refractive indexes (nD) of the sealing resin 16, the adhesive 9, and the transparent resin plate 5, the difference between the maximum value and the minimum value may be 10% or less of the average value, and 5% or less. And even better. By reducing the optical refractive index between the sealing resin 16 or the adhesive 9 and the transparent resin plate 5, the reflection at the interface between them can be kept small. For example, EVA, which is a typical material that can be used as the sealing resin 16 or the adhesive 9, has a refractive index (nD) of about 1.49, about 1.52 for PVC (polyvinyl butyral), and about 1 for silicone resin. .51. A typical material suitable for use as the transparent resin plate 5 is about 1.58 to 1.60 for PET and PEN, and about 1.53 for COP. By combining these materials, interface reflection can be kept low. In particular, when the materials of the sealing resin 16 and the adhesive 9 are used, it is preferable to use COP as the transparent resin plate 5 because the interface reflection can be minimized.

  The recess 5h of the transparent resin plate 5 may be formed when these materials are processed into a sheet shape, or may be formed by groove processing after forming the sheet shape. As the groove processing, ultrasonic processing, laser processing, or the like can be used. In the figure, the recess 5h is formed in a groove shape with a U-shaped cross section, but may be V-shaped.

  The material of the adhesive 9 is a material that is transparent and can maintain adhesion between the transparent resin plate 5 and the semiconductor substrate 1 even at a processing temperature at which the sealing resin 16 is cured. As such a material, for example, silicone resin, EVA cured in advance before curing of the sealing resin 16, or the like can be used. In particular, the thermosetting silicone resin may be less deformed even by heating when the sealing resin 16 is cured.

  Next, the method for manufacturing the solar cell module according to the first embodiment will be described using a single crystal silicon substrate as an example. 5 to 9 are partial cross-sectional views illustrating a method for manufacturing the solar cell element 30, and FIGS. 10 to 12 are partial side views illustrating a method for manufacturing a solar cell module using the solar cell element 30.

  First, a single crystal silicon substrate is prepared as the semiconductor substrate 1 as shown in FIG. A fine concavo-convex shape (texture) is formed on the front surface 1a of the single crystal silicon substrate with an alkaline etching solution. In order to form unevenness only on the front surface 1a and keep the back surface 1b flat, the semiconductor substrate 1 is etched in a state where an etching solution is brought into contact with only the front surface 1a or a protective film is formed on the back side. Perform the process.

  Next, as shown in FIG. 6, a semiconductor layer 31 having a conductivity type opposite to that of the single crystal silicon substrate is formed on the front surface 1a. As a result, semiconductor bonding can be performed. A semiconductor layer 32 having the same conductivity type as that of the single crystal silicon substrate is formed on the front surface 1b. The semiconductor layers 31 and 32 may be amorphous semiconductors. The amorphous semiconductor layers 31 and 32 can be formed by a CVD (chemical vapor deposition) method in which impurities such as B2H5 and PH3 are added to SiH4 gas which is a raw material gas for forming silicon. In that case, the thickness of these semiconductor layers 31 and 32 is preferably about several to 20 nm. In addition, when an intrinsic semiconductor layer having a thickness of about several nanometers and almost no addition of impurities is formed under the semiconductor layer 31 and the semiconductor layer 32 to which impurities are added, a highly efficient solar cell can be obtained. Although the above is a case where the semiconductor junction is a heterojunction type composed of a single crystal semiconductor and an amorphous semiconductor, impurities may be thermally diffused in the semiconductor substrate 1 to be a homojunction type. Alternatively, the semiconductor layer 32 on the back side may have a conductivity type opposite to that of the single crystal silicon substrate, and the semiconductor layer 31 on the front side may have the same conductivity type as that of the single crystal silicon substrate.

  Next, an antireflection film 33 is formed on the front semiconductor layer 31 as shown in FIG. The antireflection film 9 is preferably made of a material having an optical refractive index between the optical refractive index of the adhesive 9 and the optical refractive index of the semiconductor substrate 1. For example, when the optical refractive index of the adhesive 9 made of resin is about 1.5 and the optical refractive index of the semiconductor layer 7 is about 4 at 500 nm close to the peak wavelength of the sunlight spectrum, the optical refractive index is 1.8. A transparent metal oxide film or nitride film of ~ 2.5 may be used. In the case of the heterojunction type, the thickness of the semiconductor layer 31 is very thin and the in-plane electrical conductivity is low. Therefore, when the antireflection film 33 is formed of a transparent conductive material such as In 2 O 3, SnO 2, or ZnO, the current collecting resistance is reduced. It is good because it drops. When the relatively thick semiconductor layer 31 is formed by thermal diffusion, a silicon nitride film, an aluminum oxide film, or the like may be used. These films can be formed by CVD, vapor deposition, sputtering, or the like. The film thickness of the antireflection film 9 is preferably a film thickness at which the reflectance decreases at the peak wavelength of the sunlight spectrum due to the interference effect.

  Next, as shown in FIG. 8, the front-side collector electrode 2 is formed on the surface of the front-side antireflection film 33, and the back-side collector electrode 3 is formed on the back side. A method for producing these electrodes is preferably a method of screen printing a metal paste in terms of mass productivity and production cost. As a method of increasing the height of the front-side collector electrode 2 while reducing the width, a method of screen printing so as to repeatedly overlap in the same pattern may be used. When the semiconductor layer 31 or the semiconductor layer 32 is an amorphous silicon heterojunction type, since the semiconductor layer 31 or the semiconductor layer 32 is crystallized by high-temperature heat treatment, it is desirable that the baking temperature after screen printing be 200 ° C. or lower. When the antireflection film 33 is insulative or the like, it is preferable to make a through hole in the antireflection film 33 under the front side collector electrode 2 so that electrical contact between the front side collector electrode 2 and the semiconductor layer 31 is realized. In the case of the homojunction type in which the semiconductor layer 31 is formed by thermal diffusion, a method of forming a through hole in the antireflection film 33 below the metal paste by baking at a high temperature may be used. In the figure, the back side collector electrode 3 is formed directly on the back side semiconductor layer 32, but a transparent conductive film may be formed between the semiconductor layer 32 and the back side collector electrode 3.

  Next, the transparent resin plate 5 is bonded to the front side of the semiconductor substrate 1 as shown in FIG. A transparent resin plate 5 having a recess 5h formed in accordance with the pattern shape of the front-side collector electrode 2 is prepared. After the liquid adhesive 9 is applied to the front surface of the semiconductor substrate 1 or the surface of the transparent resin plate 5 where the recesses 5h are formed, the front collector electrode 2 and the recesses 5h are aligned and bonded together, and then bonded by heating or the like. The agent 9 is cured. The figure shows a structure in which the adhesive 9 is completely filled between the semiconductor substrate 1 and the transparent resin plate 5, which is most preferable in terms of reliability. However, the adhesive 9 is partially on the semiconductor substrate 1. The transparent resin plate 5 may be bonded. A gap remaining between the semiconductor substrate 1 and the transparent resin plate 5 due to partial adhesion is filled with the sealing resin 16 in a later step. In addition, an electrode pattern to which the interconnector 21 is connected exists on the semiconductor substrate 1, but the transparent resin plate 5 is bonded except for a region to which the interconnector 21 is connected. The solar cell element 30 is completed by the above procedure.

  Next, a solar cell module is manufactured using the plurality of solar cell elements 30. As shown in FIG. 10, the solar cell elements 30 are connected by the interconnector 21. For the connection of the interconnector 21, low melting point solder or the like is used. In addition, the figure has shown the figure seen from the side surface, when the thickness of the interconnector 21 and the thickness of the transparent resin board 5 are substantially the same.

  Next, as shown in FIG. 11, the solar cell element 30, the sealing resin sheet 20, and the sealing material 12 that are connected to each other by the glass plate 11, the sealing resin sheet 20, and the interconnector 21 are sequentially stacked, and in vacuum The sealing process which presses with heating is performed. The sealing resin sheet 20 is obtained by forming the sealing resin 16 into a sheet shape. The sealing resin sheet 20 melts and fills the gap between the front glass plate 11 and the back sealing material 12 to fix the solar cell element 30. In this way, the solar cell module as shown in FIG. 12 is completed.

  In the solar cell module according to the first embodiment, the light that enters the transparent glass plate 11 from the front side passes through the transparent sealing resin 16a, the transparent transparent resin plate 5, and the transparent adhesive 9, and the semiconductor substrate 1 The generated carriers are separated by an internal semiconductor junction and taken out from the front side collector electrode 2 and the back side collector electrode 3.

  As described above, the solar cell element 30 according to the first embodiment has the thin-line front collector electrode 2 on at least one surface, and the transparent resin plate in which the concave portion 5h matching the shape of the front collector electrode 2 is formed. 5 is bonded to the surface of the semiconductor substrate 1. In the transparent resin plate 5, the concave portion 5 h covers the front-side collector electrode 2, and the flat region of the front-side collector electrode 2 between the concave portions 5 h is adhered to the relatively flat surface of the semiconductor substrate 1 between the front-side collector electrodes 2. ing. For this reason, even if the front-side collector electrode 2 protrudes from the surface of the semiconductor substrate 1 as in the first embodiment, the front-side collector electrode 2 can be prevented from colliding with an object and being damaged. Can do. When an object collides with the surface of the transparent resin plate 5, the force generated by the collision is distributed to the flat portion through the transparent resin plate 5 and the adhesive 9, and hardly reaches the front-side collector electrode 2. Further, even if the solar cell elements 30 are stacked and transported, the front-side collector electrode 2 is not easily damaged, so that the transport becomes easy. Further, since the transparent resin plate 5 is bonded, the semiconductor substrate 1 is reinforced, and cracks are hardly generated in the semiconductor substrate 1 even if it receives an impact from the outside. In particular, when the thickness of the transparent resin plate 5 is equal to or greater than that of the semiconductor substrate 1, the strength is excellent.

  Further, since the semiconductor substrate 1 and the transparent resin plate 5 have different coefficients of thermal expansion, there is a possibility that the front-side collector electrode 2 receives stress from the transparent resin plate 5 due to temperature change. In Embodiment 1, since the width of the opening of the recess 5h is made wider than the width of the front-side collector electrode 2, there is a gap between the front-side collector electrode 2 and the transparent resin plate 5, and the front-side collector electrode 2 is a transparent resin plate. 5 is difficult to receive stress. Therefore, the possibility that the front-side collector electrode 2 is damaged due to a temperature change is low. In particular, a resin that fills the gap between the front-side collector electrode 2 and the transparent resin plate 5 may be a flexible adhesive 9 such as EVA or silicone resin. In addition, since the width of the opening of the recess 5h is made wider than the width of the front collector 2, the alignment accuracy for placing the collector in the recess can be relaxed.

  Moreover, in the solar cell module in which the solar cell element is attached to a glass plate and sealed, the sealing resin 16 is softened and the semiconductor substrate 1 is thermally expanded with the interconnector 21 in the sealing process as described above. Since the warp is caused by the difference in the rate, the surface of the semiconductor substrate 1 hits the hard glass plate 11 and the front collector electrode 2 is damaged. In particular, in the heterojunction solar cell element 30 using an amorphous semiconductor, the baking temperature of the metal paste has to be kept low, and the adhesive force between the front-side collector electrode 2 and the base is not sufficient, and is easily damaged. However, in this Embodiment 1, since the transparent resin plate 5 is affixed on the front side collector electrode 2, even if the semiconductor substrate 1 warps, the front side collector electrode 2 does not hit the glass plate 11. Further, a concave portion 5h is formed in a portion corresponding to the front side collector electrode 2 of the transparent resin plate 5, and the transparent resin plate 5 and the semiconductor substrate 1 are bonded to each other because the substantially flat portion between the front side collector electrode 2 is bonded. The force applied to the plate 11 is dispersed in a flat portion through the transparent resin plate 5 and the adhesive 9, and hardly reaches the front-side collector electrode 2. Therefore, even if it uses sealing resin with high fluidity at the time of sealing, damage to the front side collector electrode 2 can be prevented. Further, not only at the time of sealing, but also when a soft resin is used as the sealing resin 16 even at room temperature, such as EVA, the front-side collector electrode 2 can be prevented from hitting the glass plate 11 and being damaged during use.

  Further, when the interconnector 21 is fixed on the semiconductor substrate 1, the interconnector 21 protrudes on the semiconductor substrate 1, so that it hits the glass plate 11 and a local force is applied to the semiconductor substrate 1. There was a problem of damage. In the first embodiment, the height at which the interconnector 21 protrudes is reduced by the thickness of the transparent resin plate 5 because the transparent resin plate 5 is adhered while avoiding the installation location of the interconnector 21. Since the protruding height of the interconnector 21 is reduced, local stress is hardly applied even when the interconnector 21 contacts the glass plate 11, and the possibility that the semiconductor substrate 1 is damaged is greatly reduced. In particular, if the thickness of the transparent resin plate 5 is equal to or greater than that of the interconnector 21, the interconnector 21 does not come into contact with the glass plate 11, which is even better.

Embodiment 2. FIG.
FIG. 13 is a partial cross-sectional view of the solar cell module according to the second embodiment. The solar cell module 200 of the second embodiment has the same structure as that of the first embodiment on the light receiving surface side of the semiconductor substrate 1, but the back side has the same structure as the front side of the first embodiment. That is, the collector electrode is formed on both surfaces of the semiconductor substrate 1, and the transparent resin plate 5 is bonded to both surfaces of the semiconductor substrate 1. A transparent resin plate 5a is bonded to the front side of the semiconductor substrate 1 with an adhesive 9a, and a transparent resin plate 5b is bonded to the back side of the semiconductor substrate 1 with an adhesive 9b. The back side collector electrode 3 on the back side of the semiconductor substrate 1 has a shape formed of a fine line pattern, and a recess 5j corresponding to the back side collector electrode 3 is also formed on the back side transparent resin plate 5b.

Since the semiconductor substrate 1 and the transparent resin plates 5a and 5b have different coefficients of thermal expansion, if the semiconductor substrate 1 and the transparent resin plates 5a and 5b are bonded to only one of the front side and the back side, the whole may be warped due to the stress generated by the temperature change.
However, in the second embodiment, since the transparent resin plates 5a and 5b are bonded to the front side and the back side, respectively, the same stress is generated on the front side and the back side, so that it is difficult to warp. For this reason, deformation and breakage due to temperature change can be reduced. Moreover, you may use glass as the sealing material 12 of a back surface side. In this case, the light receiving surface side and the back surface side of the entire module are made of substantially the same material, and deformation and breakage can be further reduced. Similarly to the light receiving surface side of the first embodiment, the back side collecting electrode 3 on the back side can be prevented from being damaged by hitting the sealing material 12 by the transparent resin plate 5 on the back side.

  In the figure, the back side collector electrode 3 has the same pattern as the front side collector electrode 2 on the light receiving surface side, but the width, pattern, formation position, and the like may be different. When light incident from the back surface side is used, it is preferable to use the same material as the light receiving surface side for the sealing material 12, the transparent resin plate 5 and the adhesive 9 on the back surface side. When light incident from the back side is not used, the transparent resin plate 5 and the adhesive 9 on the back side may use different materials from the light receiving side.

Embodiment 3 FIG.
FIG. 14 is a partial cross-sectional view of the solar cell module according to the third embodiment. The solar cell module 300 of the third embodiment is similar to that of the first embodiment, except that a slit 5s is formed in the transparent resin plate 5. The slit 5 s is preferably provided between the front collector 2, but may be provided in a direction intersecting with the front collector 2. For example, the slit 5s having a width of 50 μm and a length of about several tens to 10 mm in the in-plane direction is preferably formed intermittently. Since the transparent resin plate 5 is formed intermittently, the transparent resin plate 5 is not completely divided by the slits 5 s and is easily attached on the semiconductor substrate 1. The slit 5s can be formed by laser processing, machining, or the like.

  The slit 5s is filled with a sealing resin 16a. Since the semiconductor substrate 1 and the transparent resin plate 5 have different coefficients of thermal expansion, there is a possibility that the whole bonded together will be warped due to temperature changes. However, in the third embodiment, the portion of the slit 5s is easily deformed. The stress generated by the expansion and contraction of the width can be relaxed. For this reason, deformation and breakage due to temperature change can be reduced. In the above description, the slit 5s penetrating in the thickness direction is provided as a stress relaxation structure, but a similar effect can be obtained by providing a non-penetrating groove, a large number of through holes, and the like.

Embodiment 4 FIG.
FIG. 15 is a partial cross-sectional view of the solar cell module according to the fourth embodiment. The solar cell module 400 of the fourth embodiment is similar to that of the first embodiment, but the shape of the transparent resin plate 5 is different.
The transparent resin plate 5 according to the fourth embodiment has a recess 5h formed by bending. The bent valley portion becomes the concave portion 5h, and a bent peak portion is formed on the glass plate 11 side. Further, there is a flat portion that is not bent between the front-side collector electrodes 2. The bent shape can be formed by pressing, or can be formed when the transparent resin plate 5 is molded.

Since it was set as such a shape, preparation of the recessed part 5h of the transparent resin board 5 is easy, and there exists an effect which protects the front side collector electrode 2 similarly to Embodiment 1. FIG. Since the crest portion of the transparent resin plate 5 protrudes on the glass plate 11 side, this crest portion easily hits the glass plate 11, but the direction in which the folding spreads even when the crest portion hits, that is, the opening of the recess 5 h spreads. Due to the deformation in the direction, the force generated by hitting the glass plate 11 is dispersed in the flat portion of the semiconductor substrate 1 and hardly reaches the front collector electrode 2. For this reason, the effect which protects the front side collector electrode 2 fully is acquired.
Further, since the bent portion can be easily deformed similarly to the spring and is to be restored even when deformed, the stress generated by the temperature change is reduced as in the case where the slit 5s of the third embodiment is provided. be able to. In the above description, the concave portion 5h of the transparent resin plate 5 is formed in a V-shaped crease shape, but the same effect can be obtained even when the waveform shape is a curved surface.

Embodiment 5. FIG.
FIG. 16 is a partial cross-sectional view of the solar cell module according to the fifth embodiment. The solar cell module 500 of the fifth embodiment is similar to that of the first embodiment, but differs in that the groove 5v is also provided on the side of the transparent resin plate 5 facing the glass plate 11. The groove 5v is located immediately above the front-side collector electrode 2. A transparent material 13 having an optical refractive index different from that of the transparent resin plate 5 and the sealing resin 16a is provided in the groove 5v.

  The groove 5v can be produced by a method of cutting the transparent resin plate 5 by laser processing, similar to the concave portion 5h. The process after the transparent material 13 inserts the insertion is the same as in the first embodiment.

  The optical refractive index of the transparent material 13 is preferably lower by 0.1 or more than the transparent resin plate 5 and the sealing resin 16a. Examples of such a transparent material 13 include a resin containing fine bubbles, a fluororesin, and a material containing nano-sized silicon oxide fine particles. These refractive indexes are about 1.2 to 1.3, and the refractive index is lower by 0.2 to 0.3 or more than the transparent resin plate 5 and the sealing resin 16a. Alternatively, a hollow fiber encapsulated with a gas such as nitrogen gas may be inserted into the groove, and the encapsulated gas may be used as the transparent material 13. In that case, the refractive index of the transparent material 13 is about 1.0.

  FIG. 17 is a cross-sectional view illustrating an example of a light incident path of the solar cell module according to the fifth embodiment. In the following description, it is assumed that the V-shaped angle is 60 degrees and the transparent material 13 has a regular triangular prism shape. In the figure, the glass plate 11, the sealing resin 16a, and the adhesive 9 are omitted. The light L perpendicularly incident on the glass plate 11 enters the semiconductor substrate 1 through the sealing resin 16 a, the transparent resin plate 5, and the adhesive 9 in order in a portion where there is no groove 5 v. Since the sealing resin 16a, the transparent resin plate 5, and the adhesive 9 have no large refractive index difference, almost no reflection occurs at the interface. On the other hand, as shown in the figure, the light L is incident on the transparent material 13 in the groove 5v. Since there is a difference in refractive index at the interface between the transparent material 13 and the sealing resin 16a, part of the light L is reflected and returns to the incident side. The light entering the transparent material 13 is refracted at the interface with the transparent resin plate 5 because the bottom of the groove 5v is inclined. The incident angle of the light L with respect to this interface is about 60 degrees. When the refractive index of the transparent material 13 is as low as 1.0, the light that has entered at an incident angle of 60 degrees is refracted at a refraction angle of about 35 degrees at the boundary between the transparent material 13 and the transparent resin plate 5, and the transparent resin plate 5 side And then enters the semiconductor substrate 1 without passing through the front collector electrode 2. Depending on the shape of the groove 5v and the refractive index of the transparent material 13, the angle of refraction changes variously, but the width of the front collector 2 is equal to or greater than the width of the transparent collector 13 and the front collector 2 depending on the thickness of the transparent resin plate 5. Since there is a sufficient distance, the light perpendicularly incident on the glass plate 11 can enter the semiconductor substrate 1 without entering the front-side collector electrode 2. If the transparent material 13 is not present, the light incident and reflected on the front collector electrode 2 is incident on the semiconductor substrate 1 in the solar cell module 500 of the fifth embodiment, so that the power generation current increases and the power generation efficiency is improved. In addition, since the light which inclines with respect to the glass plate 11 may enter into the front side collector electrode 2, the tracking which inclines the solar cell module 500 according to a solar motion so that it may not enter into the front side collector electrode 2 as much as possible. It may be loaded on the device.

  In the above, the optical refractive index of the transparent material 13 is lower than that of the transparent resin plate 5 and the sealing resin 16a, but may be higher by 0.1 or more. As such a transparent material 13, a material in which submicron fine particles of a high refractive index inorganic material such as titanium oxide or zirconium oxide are dispersed in a transparent resin in a mass ratio of 50 to 70% can be used. A transparent material 13 having a refractive index of 1.8 or more can be obtained by applying and baking such a material in the groove 5v.

FIG. 18 is a cross-sectional view illustrating another example of the light incident path of the solar cell module according to the fifth embodiment. The light L perpendicularly incident on the glass plate 11 enters the semiconductor substrate 1 through the sealing resin 16 a, the transparent resin plate 5, and the adhesive 9 in order in a portion where there is no groove 5 v. Since the sealing resin 16a, the transparent resin plate 5, and the adhesive 9 have no large refractive index difference, almost no reflection occurs at the interface. On the other hand, as shown in the figure, the light L is incident on the transparent material 13 in the groove 5v. Since there is a difference in refractive index at the interface between the transparent material 13 and the sealing resin 16a, part of the light L is reflected and returns to the incident side. When the optical refractive index of the transparent material 13 is as high as 1.8 or more, the light that has entered at an incident angle of 60 degrees is totally reflected at the boundary between the transparent material 13 and the transparent resin plate 5, which is one slope of the groove 5v, Incidently perpendicular to the other slope. The light L that has passed through the boundary between the transparent material 13 and the transparent resin plate 5, which is the other slope, goes straight through the transparent resin plate 5 and enters the semiconductor substrate 1 without entering the front-side collector electrode 2.
Accordingly, the power generation efficiency is improved even when the optical refractive index of the transparent material 13 is high as compared with the case where the optical refractive index is low compared to the transparent resin plate 5 and the sealing resin 16a.

  The bottom of the groove 5v is inclined with respect to the surface of the glass plate 11 and the main surface of the semiconductor substrate 1, and the optical refractive index of the transparent material 13 installed therein is different from that of the transparent resin plate 5 and the sealing resin 16a. Therefore, the light path of the light L incident on the transparent material 13 does not travel straight. Since the structure for changing the optical path is directly above the front-side collector electrode 2, the light L does not enter the front-side collector electrode 2, but enters the semiconductor substrate 1 to improve power generation efficiency.

  In the above, the shape of the groove 5v is a V-shaped groove shape, and the transparent material 13 has a triangular prism shape, particularly a substantially regular triangular prism shape. Therefore, the manufacturing process is simple and the slope of the slope can be increased, so that the light path can be changed. The effect is great. Similar effects can be obtained when the groove 5v has a U-shaped or W-shaped groove instead of the V-shaped groove shape. You may make it become a lens of condensing or a diffused light by making a bottom part into a curved surface. The width of the groove 5v is preferably about the same as the width of the front collector 2, but even if it is as wide as two to three times the width of the front collector 2, a flat surface with a sufficient width between the grooves 5v. If there is.

Embodiment 6 FIG.
FIG. 19 is a partial cross-sectional view of the solar cell module according to the sixth embodiment. The solar cell module 600 of the sixth embodiment is similar to that of the second embodiment, except that conductive materials 61a and 61b are installed in the recesses 5h and 5j of the transparent resin plates 5a and 5b of the solar cell element 30. Different.
The front-side collector electrode 2 and the back-side collector electrode 3 have a fine line pattern shape, and the corresponding recesses 5h and 5j are formed as grooves along the fine line pattern. The conductive materials 61a and 61b are formed at the bottoms of the recesses 5h and 5j, and do not completely fill the recesses 5h and 5j. For this reason, the recesses 5h and 5j in which the conductive materials 61a and 61b are formed are recessed portions with respect to the main surfaces of the transparent resin plates 5a and 5b, and the front side collector electrode 2 and the back side protruding from the main surface of the semiconductor substrate 1 This is the portion where the collector electrode 3 is inserted. The conductive materials 61a and 61b are in contact with the front-side collector electrode 2 and the back-side collector electrode 3 in the corresponding recesses 5h and 5j. Although it is most desirable that each electrode and each conductive material are in contact with each other over the entire length in the longitudinal direction of the fine line pattern, it may be partial. The conductive materials 61a and 61b are formed by a method such as application of a metal paste or metal plating. The material of the conductive materials 61a and 61b may be a metal material such as silver, copper, nickel, chromium, or an alloy thereof. For example, a conductive material containing nano-sized metal particles may be used for electrical connection between the front-side collector electrode 2 and the back-side collector electrode 3 and the conductive materials 61a and 61b.

  FIG. 20 is a top view showing the semiconductor substrate 1 of the solar cell element 30 of the sixth embodiment and the front-side collector electrode 2 thereon. The solar cell element includes a rectangular semiconductor substrate 1 and a front-side collector electrode 2 having a shape of a fine line pattern in which straight fine lines are arranged in parallel at regular intervals on the semiconductor substrate 1. The direction in which the front-side collector electrode 2 extends is parallel to the rectangular short-side direction of the semiconductor substrate 1. In the figure, the front-side collector electrode 2 is not formed up to the end of the semiconductor substrate 1, but it may be formed up to the end. Although only the top surface is shown in the figure, the shape of the back side collector electrode 3 on the opposite side is the same as that of the front side collector electrode 2.

FIG. 21 is a top view showing the transparent resin plate 5a of the solar cell element 30 according to the sixth embodiment. The transparent resin plate 5 a is a rectangle that is slightly larger in size than the semiconductor substrate 1, and has a recess 5 h that matches the pattern of the front-side collector electrode 2. A conductive material 61a is formed at the bottom of the recess 5h. In the present embodiment, the interconnector as shown in FIG. 3 does not exist on the surface of the semiconductor substrate 1, and only the grid-shaped collector electrode 2 is formed. Since there is no interconnector, light is not shielded by the interconnector, so that the amount of light that can be used increases, contributing to power generation. On the other hand, since the grid-shaped collector electrode 2 needs to pass a current from one end to the other end, the voltage drop at the collector electrode 2 may increase. For example, the electric resistance at the time of energization compared with FIG. 3 is about 4 times, and it is necessary to lower the wiring resistance of the collector electrode 2 in order to prevent an increase in conduction loss with respect to power. Therefore, in the present embodiment, the conductive material 61a, 61b is inserted between the collector electrode 2 and the transparent resin plates 5a, 5b in the recesses 5h, 5j to enhance the conductivity around the collector electrode 2.
Hereinafter, a structure using the conductive materials 61a and 61b will be described. For example, the collector electrode 2 has a width of about 75 μm and a height of about 35 μm. In order to maintain the same resistance as when two interconnectors are present, the cross-sectional area of the conductive portion formed by filling the collector electrode 2 and the concave portion 5h needs to be about four times. In order to satisfy this, for example, as the conductive materials 61a and 61b, when having the same resistivity as the collector electrode 2, a thickness of about 105 μm in the vertical direction is formed in the recesses 5h and 5j with the same width as the collector electrode 2. What is necessary is just to form the metal layer which has. The width in this case is an effective value along the recesses 5h and 5j. That is, the cross-sectional area may be three times that of the collector electrode 2. At this time, the concave portion is set to a depth that allows the collector electrode 2 and the conductive materials 61a and 61b to be accommodated in a direction perpendicular to the substrate.
The concave portions 5h and 5j in which the conductive materials 61a and 61b are formed and the collector electrode 2 are joined after the liquid adhesive 9 is applied to the front surface of the semiconductor substrate 1 or the transparent resin plate 5 as in the first embodiment. The collector electrode 2 and the recesses 5h and 5j are aligned and bonded together, and are formed by curing together with the adhesive 9 by heating or the like. After that, in the vacuum sealing heating of the solar cell element with a heat process of about 150 ° C. with modularization, the conductive materials 61 a and 61 b and the collector electrode 2 are joined by substantially thermocompression bonding again. Is possible. The heating temperature at the time of vacuum sealing is preferably about 150 ° C. so as not to cause deterioration of solar cell characteristics due to high temperature. Therefore, it is desirable to use a paste that melts or hardens at a temperature of about 150 ° C. to 180 ° C. for the conductive materials 61a and 61b filling the collector electrode 2 and the concave portions 5h and 5j above.

  The conductive materials 61a and 61b at the bottom in the recess 5h may be formed by a plating method. Compared to metals that are usually formed by screen printing or the like, metals formed by plating have a lower resistivity. Specifically, the metal formed by plating shows a resistivity equivalent to that of a bulk metal. For example, the resistivity at 20 ° C. can be expected to be about 1.6 μΩcm for silver and about 1.7 μΩcm for copper. On the other hand, since the resistivity of silver formed by screen printing is about 7 μΩcm, the thickness can be suppressed to about 25 μm when the conductive materials 61 a and 61 b are formed by plating. What is necessary is just to connect between a plating layer and the collector electrode 2 with a thin conductive adhesive, solder, etc. FIG. Since the transparent resin plate 5 is an insulator, a plating layer can be formed by using an electroless plating method. Note that the conductivity may be increased by other methods such as inserting metal strips as the conductive materials 61a and 61b.

  In addition, a connection region 62a made of a conductive material is formed at one end along the long side of the rectangle of the transparent resin plate 5a. The conductive material of the connection region 62a may be the same material as the conductive material 61a in the recess 5h, or may be a different material. The connection region 62a is in contact with the conductive material 61a in the plurality of different recesses 5h to electrically connect the conductive materials 61a. The conductive material of the connection region 62a is continuously formed in the plurality of recesses 5h and the flat surface of the transparent resin plate 5a between the plurality of recesses 5h. The connection region 62 a is formed at a position that protrudes from the end of the semiconductor substrate 1 when the transparent resin plate 5 a and the semiconductor substrate 1 are bonded together. In the case of the figure, the length of the rectangular short side of the transparent resin plate 5a is longer than the length of the short side of the semiconductor substrate 1, and the length of the transparent resin plate 5a when the transparent resin plate 5a is bonded to the front side of the semiconductor substrate 1 is shown. The part along the side protrudes. A connection region 62a is formed at the protruding portion. In addition, although the above demonstrated the transparent resin board 5a bonded together on the front side, the shape of the back side collector electrode 3 on the back side and the transparent resin board 5b bonded on the back side are also the same shape.

  FIG. 22 is a perspective view showing the solar cell element according to the sixth embodiment. The structure which bonded the semiconductor substrate 1 of FIG. 20, the transparent resin board 5a of FIG. 21, and the transparent resin board 5b of the back side is shown. The transparent resin plate 5a bonded to the front side of the semiconductor substrate 1 and the transparent resin plate 5b bonded to the back side are inverted 180 degrees when viewed from the direction perpendicular to the main surface of each semiconductor substrate 1. In other words, the connection region 62 a on the front side and the connection region 62 b on the back side protrude from the opposite ends of the semiconductor substrate 1.

FIG. 23 is a partial cross-sectional view showing an example of a solar cell element connection structure of solar cell module 600 of the sixth embodiment. Adjacent solar cell elements 30 are installed such that the connection region 62a and the connection region 62b that protrude from the end of each semiconductor substrate 1 face each other. The solar cell elements 30 are connected in series by electrically connecting the connection region 62a and the connection region 62b. The transparent resin plates 5a and 5b may be deformed so that the connection region 62a and the connection region 62b are in direct contact with each other, and are electrically connected via a conductive connection material 66 as shown in the figure. Also good. As the connection material 66, for example, a material made of a metal paste, a rectangular copper wire covered with solder, or the like can be used. If the thickness of the connection material 66 is equal to or greater than the thickness of the semiconductor substrate 1, the contact between the connection material 66 and the connection regions 62a and 62b may be good.
Further, an anisotropic conductive film may be used for the connection material 66. When a general conductor is used for the conductive connection material 66, if a positional shift occurs when the resin plates 5a and 5b are bonded together, the solar cell elements 30 and grids adjacent to each other in the left-right direction in FIG. There may be a short circuit due to physical contact with the electrode 2. By using an anisotropic conductive film for the conductive connection material 66, positional displacement occurs when the upper and lower resin plates are bonded together, or the connection material 66 is deformed by the pressing force when the upper and lower resin plates are bonded together. Thus, even if the connection material 66 comes into contact with the semiconductor substrate 1 or the grid collector electrode 2, no short circuit occurs. Moreover, what is necessary is just to selectively heat and pressurize a connection area | region in the heating and pressurization process at the time of connecting an anisotropic conductive film. Since the upper and lower resin plates have low thermal conductivity, the risk of damaging the semiconductor substrate 1 in the connecting step of the anisotropic conductive film is small. This method makes it possible to increase productivity in the connection process between the solar cell modules 600.

  As described above, the solar cell element of the sixth embodiment includes the conductive material 61a in contact with the front-side collector electrode 2 and the back-side collector electrode 3 in the recesses 5h and 5j facing the front-side collector electrode 2 and the back-side collector electrode 3, respectively. Since it has 61b, there exists an effect similar to the cross-sectional area of the front side collector electrode 2 and the back side collector electrode 3 increasing, and since the resistance loss accompanying current collection falls, conversion efficiency improves. Although the above is formed on both the front side and the back side, only the front side may be used. Further, the transparent resin plates 5a and 5b protrude from the end of the semiconductor substrate 1 and have conductive connection regions 62a and 62b connected to the conductive materials 61a and 61b in the recesses 5h and 5j in the protruding region. Adjacent solar cell elements are electrically connected to each other through the connection regions 62a and 62b. That is, the transparent resin plates 5a and 5b having the conductive materials 61a and 61b have a function of an interconnector. For this reason, the electrical connection between solar cell elements becomes easy. In particular, in Embodiment 6, the shape of the semiconductor substrate 1 is rectangular, and the direction in which the front side collector electrode 2 and the back side collector electrode 3 extend is parallel to the short side of the rectangle. The resistance of the back-side collector electrode 3 is reduced, and a good connection is possible without using an interconnector such as a copper wire.

Modification 1
The difference is that a resin sheet 5c having a low flexural modulus is used instead of the transparent resin plate 5b on the back side (the shape is the same as the transparent resin plate 5b in FIG. 19). When the solar cell element 30 has a sufficient light confinement effect, the amount of light emitted to the back surface side of the solar cell element 30 is small. Therefore, in the structure as shown in FIG. 19, the light to the transparent resin plate 5b on the back surface side Almost no re-incidence effect is obtained. Therefore, in this case, a soft resin sheet 5c with low transparency can be used on the back surface. Since the hardness is lower than when the transparent resin plate 5b is used, when an external impact is applied, the stress applied to the semiconductor substrate 1 is reduced and the semiconductor substrate 1 is less likely to crack. As the resin sheet 5c, a resin sheet that is not easily deteriorated by heating in the sealing step is suitable. For example, fluororubber having excellent heat resistance may be used. As described in the first embodiment, the flexural modulus of PET or PEN used for the transparent resin plate 5b is about 2400 MPa or more, whereas when a fluororubber resin sheet is used, the flexural modulus is Since it is approximately 5 to 20 MPa, when an external impact is applied, the stress applied to the semiconductor substrate 1 is reduced to about 1/100.
Modification 2
In the connection structure shown in FIG. 23, the solar cell module 600 is formed in such a manner that a gap between adjacent solar cell elements is filled with sealing resin, the glass plate 11 is omitted, and the transparent resin plate 5a on the light receiving surface side is exposed. It may be configured. Since there is no glass plate 11, the loss at the time of permeate | transmitting a glass plate can be eliminated. In this case, the sealing material 12 may be formed of a glass plate to ensure the strength of the entire module. In order to increase the weather resistance of the exposed surface of the transparent resin plate 5a, the reliability can be enhanced by applying an inorganic coating to the exposed surface.

Embodiment 7 FIG.
FIG. 24 is a partial cross-sectional view of solar cell module 700 of the seventh embodiment. The solar cell module 700 of the seventh embodiment is similar in configuration to the light receiving surface side of the semiconductor substrate 1 as in the sixth embodiment, but includes a scatterer 63 in the resin plate 5b on the back surface side. There are features. Since the transparent resin plate 5a on the light receiving surface side needs to introduce as much sunlight as possible into the inner solar cell substrate, it is necessary to use a material that absorbs as little light as possible. On the other hand, when silicon is used as the solar cell substrate material, the wavelength component that passes through the solar cell substrate and reaches the back surface side of the sunlight incident on the light receiving surface of the semiconductor substrate 1 is approximately longer than about 900 nm. Infrared. Therefore, the transparent resin plate 5b may be transparent in the near infrared region.
The scatterer 63 efficiently scatters a wavelength range of 900 nm to 1200 nm in which the spectral sensitivity of silicon is large. For example, spherical titanium oxide fine particles and silver fine particles are suitable. For example, titanium oxide fine particles having an average particle diameter of 400 nm to 700 nm may be used. Silver particles having a flat shape may be used. The average diameter of the silver fine particles is preferably in the range of 100 nm to 300 nm.
By introducing these scatterers into the transparent resin plate 5b, the light emitted to the back surface side of the semiconductor substrate 1 is scattered, and a part of the light reenters from the back surface of the semiconductor substrate 1. The arrows described in FIG. 24 indicate an example in which transmitted light is scattered and re-entered. Therefore, compared with the case where a transparent resin plate is disposed on the back side in the same manner as the light receiving surface, an effect of increasing the generated current can be obtained.
In addition, the ratio of scattering can be increased by inclining the distribution of the scatterers 63 and distributing the scatterers 63 at a high concentration on the semiconductor substrate 1 side.
In addition, a layer including the scatterer 63 may be provided on a flat surface between the concave portions 5j of the transparent resin plate 5b to scatter near infrared rays transmitted through the semiconductor substrate 1. On the other hand, the method of dispersing the scatterer 63 in the transparent resin plate 5 is advantageous in that the transparent resin plate 5b is easy to handle and the production efficiency of the solar cell module 700 is high.

Modified example.
As the scatterer 63 included in the resin plate on the back side, a phosphor that causes up-conversion can be used. Infrared light having a wavelength longer than 1200 nm contained in sunlight hardly contributes to power generation even when it is incident on the solar cell substrate because silicon has a low spectral sensitivity in silicon solar cells. By re-entering light from the back side of the semiconductor substrate 1 into light having a wavelength of 300 to 1200 nm that contributes to power generation in the solar cell element by wavelength conversion in the phosphor, re-incident from the back surface by the scatterer. An increase in power generation current due to light can be expected.

  The partial structures described in the above embodiments may be combined as long as no technical contradiction occurs.

  The solar cell element and the solar cell module of the present invention are useful for improving reliability and yield during production.

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate, 1a Front side surface, 2b Back side surface, 2 Front side collector electrode, 3 Back side collector electrode, 5, 5a, 5b Transparent resin plate, 5c Resin sheet, 5h, 5j Concave part of transparent resin plate, 5p Transparent resin plate Convex part, 5s slit, 5v V groove, 9, 9a, 9b adhesive, 11 glass plate, 12 sealing material, 13 transparent material, 16, 16a, 16b sealing resin, 21 interconnector, 30 solar cell element, 31 semiconductor layer of reverse conductivity type, 32 semiconductor layer of the same conductivity type, 33 antireflection film, 61, 61a, 61b conductive material, 62, 62a, 62b connection region, 63 scatterer, 66 connection material, 100, 200, 300 , 400, 500, 600, 700 Solar cell module.

Claims (2)

A semiconductor substrate with a junction having photovoltaic power;
A plurality of collector electrodes formed on the first surface of the semiconductor substrate and arranged in parallel with each other at regular intervals ;
A back electrode formed on a second surface to be the back surface of the first surface of the semiconductor substrate;
A recess that covers the collector electrode is formed at a position facing each of the collector electrodes, and a first conductive member that is connected to the collector electrode and is conductive is provided in the recess, and the collector electrode and the first surface are connected to each other. A transparent resin plate disposed to cover and having a first connection region at a position protruding from an end of the semiconductor substrate;
A recess that covers the back electrode is formed at a position that faces the back electrode, and has a second conductive member that is connected to the back electrode and is conductive in the recess, so as to cover the back electrode and the second surface. And a rear resin plate provided with a second connection region at a position protruding from the end of the semiconductor substrate,
A solar cell module in which solar cell elements having
The first connection region and the second connection region of the adjacent solar cell elements are arranged so as to overlap each other and are connected via a conductive connection portion, and the one solar cell element is adjacent to each other between the adjacent solar cell elements. A solar cell module, wherein the collector electrode is electrically connected to the back electrode of the other solar cell element.   The solar cell module according to claim 1, wherein the connecting portion is an anisotropic conductive film.

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