WO2011122656A1 - Solar cell and solar cell module - Google Patents

Abstract

Disclosed is a solar cell equipped with collector electrodes that are capable of improving the incidence of light to the solar cell, even in cases in which the width and thickness thereof are not increased. Also disclosed is a solar cell module using the same. The solar cell (5) is equipped with a first surface (18), a second surface (21), and collector electrodes (222a, 222b, …) that are formed upon the first surface (18), wherein the collector electrodes (222a, 222b, …) include at least a reflective conducting material and a resin, the weight concentration of the reflective conducting material in the collector electrodes (222a, 222b, …) is higher on the upper surface side of the collector electrodes (222a, 222b, …) in comparison to the first surface (18) side, and the weight concentration of the resin in the collector electrodes is higher on the aforementioned first surface (18) side of the aforementioned collector electrodes than the upper surface side.

Description

Solar cell and solar cell module

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

In recent years, as the demand for energy sources that have little impact on the environment has increased, solar cell fields such as solar cell systems using solar cells and solar cell applied products have attracted attention.

A solar cell system, a solar cell application product, or the like includes, for example, one or more solar cell modules, and the solar cell module includes one or more solar cells.

FIG. 11 is a top view of a solar battery cell in a conventional solar battery module.

As shown in FIG. 11, the solar battery cell 100 has a surface-side electrode 102 on the surface 101 that is the light-receiving surface side, and a back-side electrode (not shown) on the back surface.

The front-side electrode 102 includes a plurality of fine- finger finger electrodes 102a, 102a,... Serving as collecting electrodes for collecting carriers generated when light enters the solar battery cell 100, and the carriers are connected to the outside. The bus bar electrodes 102b and 102b are used to take out.

The surface-side electrode 102 is formed, for example, by printing a conductive paste on the surface 101 by an offset printing method, a screen printing method, or the like.

Since the finger electrodes 102a, 102a,... Shield light incident on the solar cell 101, the solar cell 101 has a problem that the output is reduced.

As a method for solving this problem, for example, a method is described in which a conductive paste having a predetermined range of viscosity is printed a plurality of times by an offset printing method to form a collector electrode (see, for example, Patent Document 1).

In the case of such a method, it is disclosed that a collector electrode having a small width and a large thickness can be formed, and shielding of incident light by the collector electrode can be reduced.

Patent Document 1: Japanese Patent Application Laid-Open No. 2007-44974

However, the above-described method has a problem that the collector electrode needs to be thin and thick, and the degree of freedom in designing the collector electrode is reduced.

The present invention has been made in view of the above problems, and uses a solar cell including a collector electrode capable of improving the light incidence on the solar cell even when the narrow width and thickness are not increased, and the same. A solar cell module is provided.

A solar battery cell according to the present invention is a solar battery cell including a first surface, a second surface, and a collector electrode formed on the first surface, wherein the collector electrode is at least A weight concentration of the reflective conductive material in the collector electrode is higher on the upper surface side of the collector electrode than on the first surface side, and the weight concentration of the reflective conductive material in the collector electrode The weight concentration of the resin is characterized in that the first surface side in the collector electrode is higher than the upper surface side. In such a solar battery cell, since the weight concentration of the resin is increased on the first surface side in the collector electrode, the weight concentration of the reflective conductive material is increased on the upper surface side of the collector electrode. The light reflectance of the upper surface and upper side surface of the collector electrode can be increased while strengthening the adhesion of the collector electrode to the solar battery cell. As a result, the output of the solar battery module including such a solar battery cell can be increased.

The collector electrode includes at least a reflective conductive material and a resin at a portion formed in a region where light strikes, and the weight concentration of the reflective conductive material in the collector electrode is such that the upper surface side of the collector electrode is The weight concentration of the resin in the collector electrode may be higher than that on the first surface side, and the first surface side in the collector electrode may be higher than the surface side. The collector electrode may be a plurality of finger electrodes, and may have other shapes. In addition to the collector electrode, the bus bar electrode may have the same configuration.

Further, the resin contains at least the first resin and the second resin having higher elasticity than the first resin, and the second resin is more on the first surface side than on the upper surface side. It is characterized by the existence. Here, the presence of the second resin includes a configuration in which the second resin is not present on the upper surface side.

In this case, a large amount of the second resin having high elasticity is present on the first surface side, and the collector electrode relieves the stress caused by the difference in thermal expansion coefficient between the collector electrode and the base of the solar battery cell. Adhesiveness on the solar cell becomes higher, and the reliability is improved.

The collector electrode includes a plurality of layers, and the weight concentration of the reflective conductive material is higher in the uppermost layer of the plurality of layers than in the lowermost layer of the plurality of layers, and the weight concentration of the resin is The lowest layer of the plurality of layers is higher than the uppermost layer of the plurality of layers.

In this case, since the weight concentration of the reflective conductive material on the upper surface side of the collector electrode is increased, the configuration of increasing the weight concentration of the resin on the first surface side in the collector electrode can be easily formed. preferable.

The uppermost layer of the collector electrode is formed so as to cover the lower layer.

In this case, since the area with high reflectivity increases on the surface of the collector electrode, the reflection at the collector electrode can be enhanced. Therefore, the output of the solar battery module including such a solar battery cell can be increased.

Furthermore, at least a part of the uppermost layer of the collector electrode is formed so as to be in contact with the first surface.

In this case, adhesion of the collector electrode to the substrate of the solar battery cell is further enhanced, and when the first surface has conductivity, the collector electrode is the uppermost layer in which the weight concentration of the reflective conductive material is high. Since the end portion is in direct contact with the first surface, the contact resistance between the collector electrode and the first surface is reduced, and the output of the solar cell is further improved.

Further, in the case of a configuration including a collector electrode on the second surface, the collector electrode includes at least a reflective conductive material and a resin, and the weight concentration of the reflective conductive material in the collector electrode is the collector concentration. Even if the upper surface side of the electrode is higher than the second surface side, and the weight concentration of the resin in the collector electrode is higher on the second surface side in the collector electrode than on the upper surface side. Good.

In this case, the light reflectance of the upper surface and upper side surface of the collector electrode can be increased while strengthening the adhesion of the collector electrode to the base of the solar cell. As a result, the output of the solar battery module including such a solar battery cell can be increased.

In the collector electrode, a portion formed in a region where the light strikes includes at least a reflective electric material and a resin, and the weight concentration of the reflective conductive material in the collector electrode is such that the upper surface side of the collector electrode is The weight concentration of the resin in the collector electrode may be higher than that on the second surface side, and the second surface side in the collector electrode may be higher than the surface side.

The collector electrode may be a plurality of finger electrodes, and may have other shapes. In addition to the collector electrode, the bus bar electrode may have the same configuration.

Further, the resin contains at least the first resin and the second resin having higher elasticity than the first resin, and the second resin is more on the second surface side than on the upper surface side. May be present. Here, the presence of the second resin includes a configuration in which the second resin is not present on the upper surface side. In this case, a large amount of the second resin having high elasticity is present on the first surface side, and the collector electrode is used to relieve stress caused by a difference in thermal expansion coefficient between the collector electrode and the base of the solar battery cell. The adhesion to the solar cell base becomes higher, and the reliability is improved.

The collector electrode includes a plurality of layers, and the weight concentration of the reflective conductive material is higher in the uppermost layer of the plurality of layers than in the lowermost layer of the plurality of layers, and the weight concentration of the resin is The lowermost layer of the plurality of layers may be higher than the uppermost layer of the plurality of layers.

In this case, since the weight concentration of the reflective conductive material on the upper surface side of the collector electrode is increased, the configuration of increasing the weight concentration of the resin on the second surface side in the collector electrode can be easily formed. preferable.

The uppermost layer of the collector electrode may be formed so as to cover the lower layer.

In this case, since the area with high reflectivity increases on the surface of the collector electrode, the reflection at the collector electrode can be enhanced. Therefore, the output of the solar battery module including such a solar battery cell can be increased.

Furthermore, at least a part of the uppermost layer of the collector electrode is formed so as to be in contact with the second surface.

In this case, when the collector electrode is further adhered to the base of the solar battery cell and the second surface has conductivity, the collector electrode is the end of the uppermost layer where the weight concentration of the reflective conductive material is high. Since the portion is in direct contact with the second surface, the contact resistance between the collector electrode and the second surface is reduced, and the output of the solar battery cell is further improved.

Furthermore, it is a solar battery module provided with the above-mentioned solar battery cell, and is provided with a translucent member, a back surface side protection member, and a plurality of the solar battery cells between them.

In this case, an arrangement in which the translucent member and the upper surface of the solar battery cell face each other is preferable.

In this case, the solar cell has a high light reflectance of the collector electrode. As a result, the rate at which the light reflected by the collector electrode is reflected by the translucent member or the like and is incident on the solar cell increases, and the output of the solar cell module can be increased. Moreover, since the said photovoltaic cell has the strong adhesion | attachment to the said photovoltaic cell of the said collector electrode, the reliability of a photovoltaic module increases.

Further, the back surface side protective member is a translucent member.

In this case, since light is also incident from the back side, the output of the solar cell module is further improved. In this case, an arrangement in which the translucent member and the lower surface of the solar battery cell face each other is preferable. In this case, in particular, the solar cell is preferably a double-sided light-receiving solar cell, and the collector electrode on the upper surface and the lower surface side has at least a reflective conductive material and a resin formed in a region that is exposed to light. And the weight concentration of the reflective conductive material in the collector electrode is higher on each upper surface side of the collector electrode than the first and second surface sides, and the weight concentration of the resin in the collector electrode Preferably, the first and second surface sides in the collector electrode are higher than the respective surface sides.

The translucent member may be a glass plate, a resin plate, a resin formed by coating, or the like.

Further, the upper surface and the lower surface may be upper and lower surfaces of a conductive body such as a semiconductor substrate, a semiconductor layer, or a transparent conductive film. The upper surface and the lower surface may be textured surfaces.

The present invention can enhance the adhesion of the collector electrode to the substrate of the solar battery cell and increase the reflectivity of the collector electrode. Therefore, the solar battery cell is highly reliable and capable of high output. And a solar cell module using the same can be provided.

It is a top view of the solar cell module which concerns on 1st Embodiment of this invention. It is a perspective view of the solar cell module which concerns on 1st Embodiment of this invention. FIG. 2 is a partial cross-sectional view of the solar cell module along A-A ′ in FIG. 1. 4A is a top view of the solar battery cell used in the solar battery module according to the first embodiment of the present invention, FIG. 4B is a back view of the solar battery cell, and FIG. 4C is the present invention. It is a top view for demonstrating the connection of the photovoltaic cell in the solar cell module which concerns on 1st Embodiment of this, and an electroconductive connection member. It is a partial cross section figure of the solar cell module which concerns on 1st Embodiment. It is a partial cross section figure of the solar cell module which concerns on 3rd Embodiment of this invention. It is a partial cross section figure of the solar cell module which concerns on 4th Embodiment of this invention. It is a partial cross section figure of the solar cell module which concerns on 5th Embodiment of this invention. It is a partial cross section figure of the solar cell module which concerns on other embodiment of this invention. It is a partial cross section figure of the solar cell module which concerns on other embodiment of this invention. It is a top view of the photovoltaic cell in the conventional solar cell module.

Next, embodiments of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.
(First embodiment)
A single-sided light-receiving solar cell module according to a first embodiment of the present invention will be described.

Referring to FIGS. 1 to 3, reference numeral 1 denotes a solar cell module. The solar cell module 1 is made of, for example, a transparent surface side cover 2 such as white reinforced glass, and a weather resistance made of a resin film such as polyethylene terephthalate (PET). A plurality of solar cells 5, 5,... Disposed between the back side cover 3 and the front side cover 2 and the back side cover 3 with a filler 4 such as ethylene vinyl acetate (EVA). A strip-shaped (band-shaped) strip having a width of 0.5 mm to 3 mm and a thickness of 100 to 300 μm made of a flat copper wire or the like whose surface is covered with a solder layer (conductive layer) such as Sn—Ag—Cu having a thickness of 1 to 50 μm A plate-like structure composed of linear solar cell groups 7, 7,... Electrically connected in series by the conductive connection members 6, 6,..., Aluminum that supports the structure, etc. Made of metal And a frame 8.

Each of the solar cell groups 7, 7,... Is arranged in parallel with each other, and each predetermined adjacent solar cell group 7, 7 so that the solar cell groups 7, 7,. ,...,...,...,...,... Flat copper wire whose surface is coated with a solder layer (conductive layer) such as Sn—Ag—Cu having a thickness of 1 to 50 μm Are connected by soldering with a strip-like (band-like) conductive connection member 9 having a width of 0.5 mm to 3 mm and a thickness of 100 to 300 μm, and the other end side of the other adjacent solar cell groups 7 and 7 is electrically conductive. The conductive connecting members 6, 6,... Have a width of 0.5 mm to 3 mm and are made of a flat copper wire whose surface is covered with a solder layer (conductive layer) such as Sn—Ag—Cu having a thickness of 1 to 50 μm. Solder-connected to 100 to 300 μm L-shaped conductive connecting members 10 and 11.

With this configuration, the plurality of solar cells 5, 5,... Of the solar cell module 1 are arranged in a matrix.

In the outermost solar cell groups 7, 7,..., The conductive connection members 6, 6,. A width of 0.5 mm to 3 mm, a thickness of 100 to 100 mm, made of a flat copper wire whose surface is covered with a solder layer (conductive layer) of Sn—Ag—Cu or the like having a thickness of 1 to 50 μm for extracting electric output from the module 1. 300 μm L-shaped connection members (output extraction connection members) 12 and 13 are connected by soldering.

The portions intersecting between the L-shaped connecting members 10 and 11 and the L-shaped connecting members 12 and 13 and between the L-shaped connecting member 11 and the L-shaped connecting member 13 are as follows. An insulating member such as an insulating sheet such as polyethylene terephthalate (PET) (not shown) is interposed.

Although not shown in the drawings, the front end side portions of the L-shaped connecting member 10, the L-shaped connecting member 11, the L-shaped connecting member 12, and the L-shaped connecting member 13 are provided on the back surface side cover 3. It is led in the terminal box 14 so that it may be located in the upper center of the solar cell module 1 through the notch.

In the terminal box 14, between the L-shaped connecting member 12 and the L-shaped connecting member 10, between the L-shaped connecting member 10 and the L-shaped connecting member 11, and L-shaped The connection member 11 and the L-shaped connection member 13 are connected by a bypass diode (not shown).

4 to 6, the solar battery cell 5 is a double-sided light receiving solar battery cell. As an example, an indium oxide containing an i-type amorphous silicon layer 16, a p-type or n-type one-conductive amorphous silicon layer 17, and tin over almost the entire surface of the n-type single crystal silicon substrate 15 having a texture structure. A transparent conductive film layer 18 made of an (ITO) film or the like is provided in this order. In addition, an i-type amorphous silicon layer 19, an amorphous silicon layer 20 having a conductivity type opposite to the one conductivity type, an indium oxide (ITO) film containing tin, etc. are transparent over substantially the entire back surface having the texture structure of the substrate 15. This is a solar cell having a so-called HIT (registered trademark) structure including a photoelectric conversion unit, which includes the conductive film layer 21 in this order.

The texture structure is a concavo-convex structure having a pyramid shape with a height of several μm to several tens of μm formed by anisotropic etching of the (100) plane of a single crystal silicon substrate.

In the present embodiment, the texture structure is a random texture structure in which a large number of pyramid shapes are irregularly arranged, and the heights (sizes) thereof are irregular, and adjacent pyramids partially overlap each other. May be. The apexes and valleys of each pyramid shape may be rounded.

The n-type single crystal silicon substrate 15 of the present embodiment is, for example, a substantially square of about 125 mm square, and the thickness is, for example, 100 μm to 300 μm.

The solar battery cell 1 contains a mixture of a reflective conductive material as a first main component such as a metal material and a resin as a second main component that functions as an adhesive such as an epoxy resin on the transparent conductive film 18. A surface side electrode 22 made of the electrode material is formed. Here, the weight concentration (wt%) of the reflective conductive material that is the first main component is higher than the weight concentration (wt%) of the resin that is the second main component.

The surface-side electrode 22 intersects with a plurality of fine- line finger electrodes 221a, 221a,... Arranged in parallel to each other as collector electrodes, and the plurality of fine- line finger electrodes 221a, 221a,. The bus bar electrodes 221b and 221b are arranged in this manner.

The surface-side electrode 22 includes a first layer 222a and a second layer 222b having different contents of the resin and the reflective conductive material of the first layer 222a, which are laminated on the transparent conductive film 18 in this order. This is a two-layer structure.

The first layer 222a on the transparent conductive film 18 side, which is the base, has a higher resin weight concentration and a reflective conductive material weight concentration than the second layer 222b on the front cover 2 side (light incident side). Low. Therefore, the second layer 222b on the surface side cover 2 side (light incident side) has a higher weight concentration of the reflective conductive material than the first layer 222a on the transparent conductive film 18 side that is the base, and the weight of the resin. The concentration is low.

In the present embodiment, the surface side electrode 22 includes, for example, an epoxy resin as the resin, a flaky silver fine powder having an average major axis of 5 to 20 μm and a spherical particle having an average particle diameter of 0.1 to 5 μm as the reflective conductive material. It consists of a mixture containing silver fine powder mixed, and the flaky silver fine powder and the spherical silver fine powder are contained in a weight ratio of 1: 1.

The first layer 222a has a thickness of 10 to 30 μm, for example, 20 μm, the content of the epoxy resin in the first layer 222a is about 10 wt%, and the flakes in the first layer 222a The total content of the silver fine powder and the spherical silver fine powder is about 90 wt%.

The second layer 222b has a thickness of 10 to 30 μm, for example, 20 μm, and the content of the epoxy resin in the second layer 222b is about 5 wt%, and the flake shape in the second layer 222b The total content of the silver fine powder and the spherical silver fine powder is about 95 wt%.

In addition, many of the flake powdery silver powders in the second layers 222b, 222b,... Of the surface-side electrode 22 have many longitudinal directions oriented parallel to the layers.

The finger electrodes 221a, 221a,... Of the surface side electrode 22 have a width of 50 to 200 μm, for example, 100 μm, and are arranged at intervals of 2 mm.

Further, the bus bar electrodes 221b and 221b of the surface side electrode 22 are each 0.1 to 1.8 mm in width, for example, a 1.3 mm straight (band) electrode.

Further, the solar battery cell 1 is made of an electrode material formed by mixing a reflective conductive material such as a metal material as the first main component and a resin such as an epoxy resin as the second main component on the transparent conductive film 21. The back surface side electrode 23 is formed.

The back surface side electrode 23 intersects with a plurality of fine wire finger electrodes 231a, 231a,... Arranged in parallel with each other as collector electrodes and the plurality of fine wire finger electrodes 231a, 231a,. Bus bar electrodes 231b and 231b.

The back electrode 23 is formed by laminating the first layer 232a and the second layer 232b having different contents of the resin and the reflective conductive material on the transparent conductive film 21 in this order. This is a two-layer structure.

The first layer 232a on the transparent conductive film 21 side, which is the base, has a higher resin weight concentration than the second layer 232b on the back cover 3 side (incident side of reflected light), and the weight of the reflective conductive material. The concentration is low. Therefore, the second layer 232b on the back surface side cover 3 side (the incident side of the reflected light) has a higher weight concentration of the reflective conductive material than the first layer 232a on the transparent conductive film 21 side which is the base, and the resin The weight concentration of is low.

In the present embodiment, the back-side electrode 23 includes, for example, an epoxy resin as the resin, a flaky silver fine powder with an average major axis of 5 to 20 μm and an average particle size of 0.1 to 5 μm as spherical silver as the reflective conductive material. It consists of a mixture containing fine powder, and the flaky silver fine powder and the spherical silver fine powder are contained in a weight ratio of 1: 1.

The first layer 232a has a thickness of 10 to 30 μm, for example, 20 μm, the content of the epoxy resin in the first layer 232b is about 10 wt%, and the flake powder in the second layer 232a The total content of the silver fine powder and the spherical silver fine powder is about 90 wt%.

Further, many of the flake powdery silver powders in the second layers 232b, 232b,... Of the back surface side electrode 23 are oriented in the longitudinal direction in a direction parallel to the layers.

The second layer 232b has a thickness of 10 to 30 μm, for example, 20 μm, the epoxy resin content in the second layer 232b is about 5 wt%, and the flake powder in the second layer 232b. The total content of the silver fine powder and the spherical silver fine powder is about 95 wt%.

The finger electrodes 231a, 231a,... Of the back side electrode 23 have a width of 50 to 200 μm, for example 150 μm, and are arranged at intervals of 1 mm.

Further, the bus bar electrodes 231b and 231b of the back surface side electrode 23 each have a width of 0.1 to 4 mm, for example, a 3 mm straight (band) electrode.

The adjacent solar cells 5, 5,... Are bus bar electrodes 221 b and 221 b of the front surface side electrode 22 of one solar cell 5 and bus bar electrodes 231 b of the back surface side electrode 23 of the other solar cell 5. The conductive connection members 6 are disposed so as to face the bus bar electrodes 221b and the bus bar electrodes 231b, respectively, so that the conductive connection members 6 and 6 are electrically connected to each other. It is fixed with an adhesive made of epoxy resin.

In the surface-side electrode 22 of the solar battery cell 5, the weight concentration of the resin contained in the first layer 222 a is larger than the weight concentration of the resin contained in the second layer 222 b, and the content of the second layer 222 b is contained. The weight concentration of the reflective conductive material is higher than the weight concentration of the reflective conductive material contained in the first layer 222a.

Therefore, the weight concentration of the reflective conductive material contained in the second layers 222b, 222b,... Is increased while the weight concentration of the resin contained in the first layers 222a, 222a,. Therefore, the light reflectance of the upper surface or upper side surface of the surface side electrode 22 can be increased while strengthening the adhesion of the surface side electrode 22 onto the solar battery cell 5.

As a result, in the solar cell module 1, among the light incident from the surface side cover 2, the light X reaching the upper surface and upper side surface of the surface side electrode 22, that is, the second layers 222 b, 222 b,. Since the light is efficiently reflected on the upper surface and the upper side surface, the amount of light X re-reflected by the surface-side cover 2 or the filler 4 increases, and as a result, a large amount of light is incident on the solar cells 5. The output of the cell 5 is improved.

As a result, in the solar cell module 1, among the light that is transmitted between the solar cells 5 and 5 or in the solar cell 5 and reflected by the back surface side cover 3 or the like, the upper surface or upper side surface of the back surface side electrode 23, That is, since the light Y reaching the second layers 232b, 232b,... Is efficiently reflected on the upper surface and the upper side surface, much light Y is re-reflected by the back surface side cover 3 or the filler 4. As a result, since a large amount of light is incident on the solar battery cell 5 also on the back surface side, the output of the solar battery cell 5 is further improved.

Further, the flake silver powder in the second layers 222b, 222b,... Of the front surface side electrode 22 and in the second layers 232b, 232b,. The flake silver powder has a major axis that reflects well, and the major axis direction of the flake-shaped silver powder is oriented in many directions in parallel with the second layers 222b, 222b, 232b, 232,. The output of the solar battery cell 5 is further improved.
(Method for manufacturing solar cell module)
Below, the manufacturing method of the solar cell module which concerns on this embodiment is demonstrated.

First, solar cells 5 having transparent electrode film layers 18 and 21 on both surfaces are prepared.

Next, a predetermined amount in a first conductive paste in which a predetermined amount of a reflective conductive material is dispersed in a paste in which a predetermined amount of resin is dissolved in a solvent and in a paste in which a predetermined amount of resin is dissolved in a solvent A second conductive paste prepared by dispersing the reflective conductive material is prepared. Here, the second conductive paste has a lower resin weight concentration and a higher weight concentration of the reflective conductive material than the first conductive paste.

Subsequently, the first conductive paste is printed in a predetermined pattern on the transparent electrode film layer 18 of the solar battery cell 5 by screen printing, offset printing, pad printing, and the like, and then dried. Is printed on the transparent conductive layer 21 of the solar battery cell 5 by screen printing, offset printing plate, pad printing plate or the like. After the conductive paste is printed in a predetermined pattern and dried, the second conductive paste is printed so as to overlap the predetermined pattern and dried.

Thereafter, the first and second conductive pastes are cured by heating at about 200 ° C. for about 1 hour, and the first layers 222a, 222a,... And the second layers 222b, 222b,. .. And the second layer 232b, 232b,... And the second layer 232b, 232b,.

Subsequently, a plurality of solar cells 5, 5,... On which the front-side electrode 22 and the back-side electrode 23 are prepared as described above are prepared, and conductive connection members 6, 6,. To do.

Next, conductive connection is made on the bus bar electrode 221b of the front surface side electrode 22 of one of the adjacent solar cells 5 and 5 and on the bus bar electrode 231b of the back surface side electrode 23 of the other solar cell 5. The solar cells 7 are manufactured by connecting the members 6, 6,... Using an adhesive made of a resin containing solder, resin, conductive filler, or the like.

Thereafter, after preparing a plurality of solar cell groups 7 and producing a structure to which the connection member 9 and the connection members 10, 11, 12, and 13 are attached, the surface side cover 2, the sealing sheet that becomes the filler 4, the structure The body, the sealing sheet to be the filler 4 and the back surface side cover 3 are laminated in this order in a thermocompression bonding manner.

Finally, the terminal box 14 and the metal frame 8 are attached to complete the solar cell module 1.

Since the manufacturing method of the present embodiment is a method using the first and second pastes containing the resin and the reflective conductive material corresponding to each layer, the first layers 222a, 222a,. The front surface side electrode 22 composed of the layers 222b, 222b,... And the back surface side electrode 23 composed of the first layers 232a, 232a,.

In the present embodiment, the second paste has a low viscosity, and screen printing, offset printing, pad printing, or the like is used to form the second layers 222b, 222b,. Since the second layers 232b, 232b,... Are formed, the flake powdery silver powder in the reflective conductive material can be easily oriented in the horizontal direction.
(Second Embodiment)
A double-sided solar cell module according to a second embodiment of the present invention will be described. In addition, the photovoltaic cell 5, the surface side electrode 22, the back surface side electrode 23, etc. are the same as that of 1st Embodiment, and difference with 1st Embodiment is mainly demonstrated.

In the second embodiment, the difference from the first embodiment is that the back surface side cover 3 in FIGS. 1 to 3 and 5 is a transparent surface side cover 2 such as white plate tempered glass like the surface side cover 2. The front side cover and the back side cover are both translucent members.

Further, the solar cell module of the present embodiment is a double-sided light receiving solar cell module, and the back side cover is made of glass or the like, so that the terminal box is provided in the vicinity of the frame body 8 in order to reduce light shielding loss, and the surface Each output extraction connecting member corresponding to the connecting members 10, 11, 12, and 13 drawn out from the side cover 2 and the back side cover 3 is led into the terminal box.

In the solar cell module of the present embodiment, light can also enter from the back surface side cover 3, and among the light incident from the back surface side cover 3, the upper surface and upper side surface of the back surface side electrode 23, that is, the second layer 232b. The light reaching 232b,... Is efficiently reflected on the upper surface and the upper side surface, so that the amount of light re-reflected by the back surface side cover 3 or the filler 4 increases. Since much light enters 5, the output of the solar battery cell 5 is improved as compared with the first embodiment.
(Third embodiment)
A solar cell module according to a third embodiment of the present invention will be described with reference to FIG.

FIG. 6 is a partial cross-sectional view of the solar cell module according to the present embodiment. Note that differences from the first embodiment will be mainly described.

The third embodiment is different from the first embodiment in that the back-side electrode 23 does not have the second layers 232b, 232b,..., But includes the first layers 232a, 232a,. Is a point.

The rest is the same as in the first embodiment, and the same or similar parts are denoted by the same reference numerals and description thereof is omitted.

Also in this embodiment, in the same manner as in the first embodiment, the light incident from the surface side cover 2 reaches the upper surface and upper side surface of the surface side electrode 22, that is, the second layers 222b, 222b,. Since the light X is efficiently reflected on the upper surface and the upper side surface, the amount of the light X re-reflected by the surface side cover 2 or the filler 4 increases, and as a result, a large amount of light enters the solar battery cell 5. Therefore, the output of the solar battery cell 5 is improved.
(Fourth embodiment)
A solar cell module according to a fourth embodiment of the present invention will be described with reference to FIG.

FIG. 7 is a partial cross-sectional view of the solar cell module according to the present embodiment. Note that differences from the first embodiment will be mainly described.

The fourth embodiment is different from the first embodiment in that the second layers 242b, 242b,... Of the surface-side electrode 22 are formed so as to cover the first layers 242a, 242a,. And the second layers 252b, 252b,... Of the back surface side electrode 23 are formed so as to cover the first layers 252a, 252a,. Others are the same as those in the first embodiment, and the same or similar parts are denoted by the same reference numerals.

In FIG. 7, the solar battery cell 1 functions as an adhesive such as a reflective conductive material, which is a first main component such as a metal material, and an epoxy resin, on the transparent conductive film 18, as in the first embodiment. A surface-side electrode 22 made of an electrode material containing a mixture of two main components is formed. Here, the weight concentration of the reflective conductive material that is the first main component is higher than the weight concentration of the resin that is the second main component.

The surface-side electrode 22 intersects with the plurality of fine- line finger electrodes 221a, 221a,... Arranged in parallel with each other as the collector electrode and the plurality of fine- line finger electrodes 221a, 221a,. Bus bar electrodes 221b and 221b.

The surface-side electrode 22 includes a first layer 242a and a second layer 242b having a different content of the resin and the reflective conductive material and the first layer 242a stacked on the transparent conductive film 18 in this order. This is a two-layer structure.

The first layer 242a on the transparent conductive film 18 side, which is the base, has a higher resin weight concentration and a reflective conductive material weight concentration than the second layer 242b on the front cover 2 side (light incident side). Low. Therefore, the second layer 242b on the surface side cover 2 side (light incident side) has a higher weight concentration of the reflective conductive material than the first layer 242a on the transparent conductive film 18 side that is the base, and the weight of the resin. The concentration is low.

In the present embodiment, the surface-side electrode 22 includes, for example, an epoxy resin as the resin, a flaky silver fine powder having an average major axis of 5 to 20 μm and a spherical particle having an average particle diameter of 0.1 to 5 μm as the reflective conductive material. It consists of a mixture containing silver fine powder mixed, and the flaky silver fine powder and the spherical silver fine powder are contained in a weight ratio of 1: 1.

The first layer 242a has a thickness of 10 to 30 μm, for example, 20 μm, the epoxy resin content in the first layer 242a is about 10 wt%, and the flakes in the first layer 242a The total content of the silver fine powder and the spherical silver fine powder is about 90 wt%.

The second layer 242b has a thickness of 10 to 30 μm, for example, 20 μm, the content of the epoxy resin in the second layer 242b is about 5 wt%, and the flaky shape in the second layer 242b. The total content of the silver fine powder and the spherical silver fine powder is about 95 wt%.

The finger electrodes 221a, 221a,... Of the surface side electrode 22 have a width of 50 to 200 μm, for example, 100 μm, and are arranged at intervals of 2 mm.

Further, the bus bar electrodes 221b and 221b of the surface side electrode 22 are each 0.1 to 1.8 mm in width, for example, a 1.3 mm straight (band) electrode.

Further, the solar battery cell 1 is made of an electrode material formed by mixing a reflective conductive material such as a metal material as the first main component and a resin such as an epoxy resin as the second main component on the transparent conductive film 21. The back surface side electrode 23 is formed.

The back surface side electrode 23 intersects with a plurality of fine wire finger electrodes 231a, 231a,... Arranged in parallel with each other as collector electrodes and the plurality of fine wire finger electrodes 231a, 231a,. Bus bar electrodes 231b and 231b.

The back electrode 23 is formed by laminating a first layer 252a and a second layer 252b having a different content of resin and reflective conductive material on the transparent conductive film 21 in this order. This is a two-layer structure.

The first layer 252a on the transparent conductive film 21 side, which is the base, has a higher resin weight concentration than the second layer 252b on the back side cover 3 side (incidence side of reflected light), and the weight of the reflective conductive material. The concentration is low. Therefore, the second layer 252b on the back cover 3 side (incidence side of the reflected light) has a higher weight concentration of the reflective conductive material than the first layer 252a on the transparent conductive film 21 side which is the base, and the resin The weight concentration of is low.

In the present embodiment, the back-side electrode 23 includes, for example, an epoxy resin as the resin, a flaky silver fine powder with an average major axis of 5 to 20 μm and an average particle size of 0.1 to 5 μm as spherical silver as the reflective conductive material. It consists of a mixture containing fine powder, and the flaky silver fine powder and the spherical silver fine powder are contained in a weight ratio of 1: 1.

The first layer 252a has a thickness of 10 to 30 μm, for example, 20 μm, the epoxy resin content in the first layer 252a is about 10 wt%, and the flake powder in the first layer 252a The total content of the silver fine powder and the spherical silver fine powder is about 90 wt%.

The second layer 252b has a thickness of 10 to 30 μm, for example, 20 μm, the epoxy resin content in the second layer 252b is about 5 wt%, and the flake powder in the second layer 252b The total content of the silver fine powder and the spherical silver fine powder is about 95 wt%.

The finger electrodes 231a, 231a,... Of the back side electrode 23 have a width of 50 to 200 μm, for example 150 μm, and are arranged at intervals of 1 mm.

Further, the bus bar electrodes 231b and 231b of the back surface side electrode 23 each have a width of 0.1 to 4 mm, for example, a 3 mm straight (band) electrode.

In the surface side electrode 22 of the solar battery cell 5, the weight concentration of the resin contained in the first layer 242 a is larger than the weight concentration of the resin contained in the second layer 242 b, and the content of the second layer 242 b is contained. The weight concentration of the reflective conductive material is larger than the weight concentration of the reflective conductive material contained in the first layer 242a.

In addition, the first layers 242a, 242a,... Of the surface side electrode 22 are covered with the second layers 242b, 242b,. The portions that are exposed to light are configured to be the second layers 242b, 242b,.

Therefore, while increasing the weight concentration of the resin contained in the first layers 242a, 242a,..., The weight concentration of the reflective conductive material contained in the second layers 242b, 242b,. Therefore, the light reflectance of the upper surface and side surface of the surface side electrode 22 can be increased while strengthening the adhesion of the surface side electrode 22 onto the solar battery cell 5.

As a result, in the solar cell module 1, the light X that has reached the surface of the surface-side electrode 22 out of the light incident from the surface-side cover 2 is efficiently reflected by the surface. As a result, the amount of light X that is re-reflected increases, and as a result, a large amount of light is incident on the solar cells 5, so that the output of the solar cells 5 is improved.

Further, the back surface side electrode 23 of the solar battery cell 5 also has a higher weight concentration of the resin contained in the first layer 252a than the weight concentration of the resin contained in the second layer 252b. The weight concentration of the reflective conductive material that BR> L is larger than the weight concentration of the reflective conductive material contained in the first layer 252a.

In addition, the first layers 252a, 252a,... Of the back side electrode 23 are covered with the second layers 252b, 252b,. The portion that is exposed to light is configured to be the second layers 252b, 252b,.

Therefore, while increasing the weight concentration of the resin contained in the first layers 252a, 252a,..., The weight concentration of the reflective conductive material contained in the second layers 252b, 252b,. Therefore, the light reflectance of the upper surface and side surface of the back surface side electrode 23 can be increased while strengthening the adhesion of the back surface side electrode 23 onto the solar battery cell 5.

As a result, in the solar cell module 1, the light Y that has passed through the solar cells 5, 5 and the solar cell 5 and has reached the surface of the back surface side electrode 23 among the light reflected by the back surface side cover 3 or the like. Is efficiently reflected by the upper surface and the side surface, and therefore, the amount of light Y re-reflected by the back surface side cover 3 or the filler 4 is increased, and as a result, the back surface side also has a large amount of light to the solar cells 5. Since it injects, the output of the photovoltaic cell 5 improves more.

In addition, since the surface side electrode 22 has a form in which the end portions of the second layers 242b, 242b,... Having a high weight concentration of the reflective conductive material are in direct contact with the transparent conductive film 18, the surface side electrode 22 and the transparent conductive film 18 and a contact resistance become small, and the output of the photovoltaic cell 5 improves.

Further, the back-side electrode 23 is also in a form in which the ends of the second layers 252b, 252b,... Having a high weight concentration of the reflective conductive material are in direct contact with the transparent conductive film 21, so that the back-side electrode The contact resistance between 23 and the transparent conductive film 21 is reduced, and the output of the solar battery cell 5 is improved.

In the above description, the first layers 242a, 242a,... Of the surface-side electrode 22 are completely covered with the second layers 242b, 242b,..., And the second layers 242b, 242b,. Although the entire region of the end portion is in direct contact with the transparent conductive film 18, the second layers 242b, 242b,... Are first so that only part of the end portion is in direct contact with the transparent conductive film 18. The layers 242a, 242a,... May be covered and an effect is obtained.

Further, the first layers 252a, 252a,... Of the back surface side electrode 23 are also completely covered with the second layers 252b, 252b,... And the ends of the second layers 252b, 252b,. The second layer 252b, 252b,... Is the first layer so that only a part of the end portion is in direct contact with the transparent conductive film 21. The layers 252a, 252a,... May be covered to obtain an effect.

The front surface side electrode 22 and the back surface side electrode 23 of the solar battery cell 5 of the present embodiment can also be manufactured using the first and second conductive pastes, for example, as in the first embodiment. In this case, the screen printing plate, offset printing plate, pad printing plate, etc. for the second layers 242b, 242b, 252b, 252b,. What has a larger pattern width, for example, about 10 μm than a printing plate, an offset printing plate, a pad printing plate, or the like may be used.
(Fifth embodiment)
A solar cell module according to a fifth embodiment of the present invention will be described with reference to FIG.

FIG. 8 is a partial cross-sectional view of the solar cell module of the present embodiment. Note that differences from the fourth embodiment will be mainly described.

The fifth embodiment is different from the fourth embodiment in that the back surface side electrode 23 does not have the second layers 242b, 242b,..., But includes the first layers 242a, 242a,. Is a point.

The rest is the same as in the fourth embodiment, and the same or similar parts are denoted by the same reference numerals and description thereof is omitted.

Also in this embodiment, as in the fifth embodiment, the second layer 242b, 242b,... Contains, while increasing the weight concentration of the resin contained in the first layer 242a, 242a,. Since the weight concentration of the reflective conductive material is increased, the light reflectance of the upper surface and the side surface of the surface side electrode 22 can be increased while strengthening the adhesion of the surface side electrode 22 onto the base of the solar battery cell 5.

As a result, in the solar cell module 1, the light X that has reached the surface of the surface-side electrode 22 out of the light incident from the surface-side cover 2 is efficiently reflected by the surface. As a result, the amount of light X that is re-reflected increases, and as a result, a large amount of light is incident on the solar cell 5, so that the output of the solar cell 5 is improved.
(Sixth embodiment)
A solar cell module according to a sixth embodiment of the invention will be described.

The sixth embodiment differs from the first embodiment in the first layers 222a, 222a,... Of the front surface side electrode 22 and the first layers 232b, 232b,. This is that the epoxy resin used in the first embodiment and a resin having higher elasticity than the epoxy resin are included, and the others are the same as in the first embodiment.

The first layers 222a, 222a ... of the front side electrode 22 and the first layers 232a, 232a ... of the back side electrode 23 are made of a resin mainly composed of the epoxy resin used in the first embodiment. Further, an epoxy resin or a urethane resin having an average molecular weight higher than that of the epoxy resin is contained as a subcomponent so that the elasticity is higher than that of the epoxy resin.

In this embodiment, the first layers 222a, 222a,... Of the front surface side electrode 22 and the first layers 232a, 232a,. Reflectivity in which the content of the subcomponent resin having higher elasticity than the main component is about 5 wt%, flaky silver fine powder having an average major axis of 5 to 20 μm and spherical silver fine powder having an average particle size of 0.1 to 5 μm are mixed. The conductive material is contained at a content rate of about 90 wt%.

Note that the second layers 222b, 222b,... Of the front surface side electrode 22 and the second layers 232b, 232b,... Of the back surface side electrode 23 are the same as in the first embodiment.

As a result, the same effects as those of the first embodiment can be obtained, and the first layers 222a, 222a,... In the layers 232a, 232a,..., The stress due to the difference in thermal expansion coefficient between the front surface side electrode 22 and the back surface side electrode 23 and the substrate 15 in these layers is relieved. Between the transparent conductive film 18 to be formed, the adhesiveness between the back-side electrode 23 and the transparent conductive film 21 to be the base is increased, and reliability is improved.

In each of the above embodiments, one type or two types of resins are contained in the first layer of the front-side electrode 22 and the first layer of the back-side electrode 23, but two or more types of resins are contained. It can also be applied to things. Further, although one type of resin is contained in the second layer of the front surface side electrode 22 and the second layer of the back side electrode 23, the present invention can also be applied to one containing two or more types of resins.

In each of the above embodiments, as in the sixth embodiment, the first layer of the front-side electrode 22 and / or the first layer of the back-side electrode 23 has a higher elasticity than the main component in addition to the main component resin. You may make it contain resin of a subcomponent.

Further, a secondary component resin having higher elasticity than the main component may be contained in the second layer.

In addition, the front surface side electrode 22 and the back surface side electrode 23 of each of the above embodiments have a two-layer structure of a first layer and a second layer, but the present invention is not limited to this and may be composed of a plurality of layers. In this case, the weight concentration of the reflective conductive material may be higher in the uppermost layer than that in the lowermost layer, and the weight concentration of the resin may be higher in the lowermost layer than in the uppermost layer. Furthermore, the weight concentration of the reflective conductive material is higher on the upper side of the uppermost layer than the lower side of the lowermost layer, and the weight concentration of the resin is higher on the lower side of the lowermost layer than the upper side of the uppermost layer. May be.

Further, the front surface side electrode 22 and the back surface side electrode 23 may have a structure without a layer structure, or a structure with only one layer. In this case, the weight concentration of the reflective conductive material may be higher on the upper side than on the lower side, and the weight concentration of the resin may be higher on the lower side than on the upper side. Further, the weight concentration of the reflective conductive material is gradually increased from the lower side to the upper side, and the weight concentration of the resin is gradually increased from the upper side to the lower side. Also good.

The solar cells of the above embodiments have been described using so-called HIT solar cells, but the present invention is applicable to various solar cells such as single crystal solar cells and polycrystalline solar cells, In addition to the double-sided light receiving type, it can also be applied to single-sided light receiving solar cells.

The polycrystalline solar battery cell or the single crystal solar battery includes, for example, an n + layer formed from a surface of a silicon substrate made of P-type polycrystal or P-type single crystal to a predetermined depth to form a pn junction, and the silicon A solar cell in which a p + layer is formed from the back surface of the substrate to a predetermined depth, a front surface side electrode 22 is formed on the n + layer, and a back surface side electrode 23 is formed on the p + layer.

In each of the above embodiments, the present invention is applied to both the finger electrode and the bus bar electrode of the front surface side electrode 22 and / or the back surface side electrode 23, but may be applied only to the finger electrode.

Moreover, in each said embodiment, although the surface side electrode 22 and the back surface side electrode 23 consist of a finger electrode and a bus-bar electrode, a surface side electrode or / and a back surface-side electrode do not have a bus-bar electrode, finger electrode 221a, A bus bar-less structure consisting only of 231a,.

Further, the back surface side electrode may be composed of an electrode having another structure different from that described above, for example, an electrode covered with a metal film on the entire surface and a bus bar electrode formed thereon.
Furthermore, the solar cell module of the present invention is not limited to the above-described embodiments. For example, the solar cell module is not limited to a configuration including a plurality of solar cells, and may be a solar cell module including one solar cell.

Also, a frameless structure without a frame may be used.

Moreover, in each said Example, although the example was given and demonstrated about the case where the surface electrode of a photovoltaic cell and the back surface electrode of an adjacent photovoltaic cell were connected in series, the connection between adjacent photovoltaic cells is the above-mentioned. Not only each embodiment but you may make it connect the surface electrodes of a photovoltaic cell adjacent to a photovoltaic cell, or back electrodes.

For example, the configuration shown in FIGS. 9 and 10 may be used. In FIG. 9 and FIG. 10, the same or similar parts as those in the first embodiment are denoted by the same reference numerals.

The solar cell module 1 shown in FIG. 9 is a set of two adjacent solar cells 5 and 5 having the same element structure, and two adjacent solar cells 5 having an element structure opposite in polarity. 5 are arranged in one set, and these are electrically connected in series by the conductive connecting members 6, 6,.

In the solar cell module 1 shown in FIG. 10, adjacent solar cells 5 and 5 have an element configuration in which the polarities are opposite to each other, and the conductive connecting members 6, 6,. 5, 5 and 5 and the back surface side electrodes 23 and 23 of the photovoltaic cells 5 and 5 are electrically connected in series.

In addition, as examples of the method for producing the front surface side electrode 22 and the back surface side electrode 23 of the solar cell module, screen printing, offset printing, pad printing, and the like have been shown.

DESCRIPTION OF SYMBOLS 1 Solar cell module 2 Front surface side cover 3 Back surface side cover 5 Solar cell 15 Single crystal silicon substrate (semiconductor substrate)
22 Front side electrode 221a Finger electrode 222a, 242a 1st layer 222b, 242b 2nd layer 221b Bus bar electrode 23 Back side electrode 231a Finger electrode 232a, 252a 1st layer 232b, 252b 2nd layer 231b Bus bar electrode

Claims (7)

1. A solar cell comprising a first surface, a second surface, and a collector electrode formed on the first surface, wherein the collector electrode includes at least a reflective conductive material and a resin. The weight concentration of the reflective conductive material in the collector electrode is higher on the upper surface side of the collector electrode than the first surface side, and the weight concentration of the resin in the collector electrode is The solar cell, wherein the first surface side is higher than the upper surface side.
2. The resin contains at least a first resin and a second resin having higher elasticity than the first resin, and the second resin is present more on the first surface side than on the upper surface side. The solar cell according to claim 1, wherein:
3. The collector electrode includes a plurality of layers, and the weight concentration of the reflective conductive material is higher in the uppermost layer of the plurality of layers than in the lowermost layer of the plurality of layers, and the weight concentration of the resin is the plurality of layers. The solar cell according to claim 1 or 2, wherein a lowermost layer of the layers is higher than an uppermost layer of the plurality of layers.
4. The solar cell according to claim 3, wherein the uppermost layer of the collector electrode is formed to cover the lower layer.
5. The solar cell according to claim 3 or 4, wherein at least a part of the uppermost layer of the collector electrode is formed so as to be in contact with the first surface.
6. It is a solar cell module provided with the photovoltaic cell as described in any one of Claims 1 thru | or 5, Comprising: A translucent member, a back surface side protection member, and one or more said solar cells between these A solar cell module comprising a cell.
7. The solar cell module according to claim 6, wherein the back surface side protection member is a translucent member.

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