JP2011211081A - Solar cell, and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell equipped with a collector electrode having an excellent adhesion, and to provide a solar cell module using the same.SOLUTION: In the solar cell 5 including a first surface 18, a second surface 21, and the collector electrodes 222a, 222b, ... formed on the first surface 18, the collector electrodes 222a, 222b, ... contain at least a reflective conductive material and a resin, the resin consists of a first resin and a second resin having a higher elasticity than that of the first resin, and a weight concentration of the second resin in the collector electrodes 222a, 222b, ... is higher on the first surface 18 side compared with the top surface side of the collector electrodes 222a, 222b, ....

Description

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

  2. Description of the Related Art In recent years, there has been a growing demand for energy sources that have little impact on the environment, and solar cell fields such as solar cell systems using solar cells and solar cell application products have attracted attention.

  A solar cell system, a solar cell application product, or the like includes, for example, one or a plurality of solar cell modules, and the solar cell module includes one or a plurality of 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 a surface 101 that is a 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.
For example, the front-side electrode 102 is formed by printing a conductive paste on the surface 101 by an offset printing method, a screen printing method, or the like.
For example, a method is described in which a conductive paste having a predetermined range of viscosity is printed a plurality of times by offset printing to form a collecting 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 since the shielding of incident light by the collector electrode can be reduced, a decrease in the output of the solar battery cell due to the shielding can be suppressed.
JP 2007-44974 A

  In order to extend the life of the solar cell, it is desirable to increase the adhesion between the collector electrode and its base, and in particular, when the collector electrode is narrower, the adhesion area between the collector electrode and its base Therefore, it is desirable to improve the adhesion between the collector electrode and the base.

  This invention is made | formed in view of the said subject, and provides the photovoltaic cell provided with the collector electrode which has good adhesiveness, and a photovoltaic cell module using the same.

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 reflective conductive material and a resin are included, and the resin includes at least a first resin and a second resin having higher elasticity than the first resin, and the weight concentration of the second resin in the collector electrode is The first surface side is higher than the upper surface side of the collector electrode. Here, the term “made of the second resin” includes a configuration in which the second resin is not provided on the upper surface side.
In the solar cell according to the present invention, the second resin having higher elasticity than the first resin relieves stress caused by the difference in thermal expansion coefficient between the collector electrode and the base of the solar cell. Adhesiveness of the collector electrode to the substrate of the solar battery cell is increased, and reliability is improved.
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, as the first resin, a resin having better light transmittance, better moisture resistance and / or better weather resistance than the second resin may be selected. In this case, the light reflectivity, moisture resistance and / or weather resistance of the collector electrode can be improved.
Furthermore, the weight concentration of the first resin in the collector electrode may be higher on the upper surface side of the collector electrode than on the first surface side. This is preferable because the characteristics of the collector electrode can be adjusted more easily. In addition, when the first resin is selected to have good light transmittance, good moisture resistance and / or good weather resistance as compared to the second resin, good light transmittance, good moisture resistance or Since there are many first resins having good weather resistance, the light reflectivity, moisture resistance and / or weather resistance of the collector electrode can be improved.
Further, the second resin may have an average molecular weight larger than that of the first resin.
In this case, the second resin can be easily configured to have higher elasticity than the first resin. In this case, the first resin can easily reduce the light absorption as compared with the second resin.

  The collector electrode may include a plurality of layers, and the weight concentration of the second resin may be higher in the lowermost layer of the plurality of layers than in the uppermost layer of the plurality of layers.

In this case, a configuration in which the weight concentration of the second resin is increased on the first surface side in the collector electrode can be easily formed, which is preferable.
Furthermore, in the case of a configuration including a collector electrode on the second surface, the collector electrode contains at least a reflective conductive material and a resin, and the resin has at least higher elasticity than the first resin and the first resin. The weight concentration of the second resin in the collector electrode may be higher on the second surface side than on the upper surface side of the collector electrode.
In this case, the second resin having higher elasticity than the first resin relieves stress caused by the difference in thermal expansion coefficient between the collector electrode and the base of the solar battery cell. Adhesion of the cell to the substrate is enhanced, and reliability is improved.
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, as the first resin, a resin having better light transmittance, better moisture resistance and / or better weather resistance than the second resin may be selected. In this case, the light reflectivity, moisture resistance and / or weather resistance of the collector electrode can be improved.
Furthermore, the weight concentration of the first resin in the collector electrode may be higher on the upper surface side of the collector electrode than on the first surface side. This is preferable because the characteristics of the collector electrode can be adjusted more easily. In addition, when the first resin is selected to have better light transmittance, better moisture resistance and / or better weather resistance than the second resin, good light transmittance, good moisture resistance or / and good weather resistance on the upper surface side. Therefore, the light reflection property, moisture resistance, and / or weather resistance of the collector electrode can be improved.
Further, the second resin may have an average molecular weight larger than that of the first resin.
In this case, the second resin can be easily configured to have higher elasticity than the first resin. In this case, the first resin can easily reduce the light absorption as compared with the second resin.
The collector electrode may be composed of a plurality of layers, and the weight concentration of the second resin may be higher in the lowermost layer of the plurality of layers than in the uppermost layer of the plurality of layers.

In this case, it is preferable because a configuration in which the weight concentration of the second resin on the second surface side in the collector electrode is increased can be easily formed.
Furthermore, the uppermost layer of the collector electrode may be formed so as to cover the lower layer.
In this case, since the second resin is less in the uppermost layer, the light reflectivity of the collector electrode is improved by making the first resin have better light transmission, better moisture resistance and / or better weather resistance than the second resin. Improves moisture resistance and / or weather resistance.
Furthermore, at least a part of the uppermost layer of the collector electrode may be formed so as to contact the second surface.
Furthermore, it is a solar cell module provided with the said photovoltaic cell, Comprising: You may equip a translucent member, a back surface side protection member, and the said several photovoltaic cell between these.
In this case, an arrangement in which the translucent member and the upper surface of the solar battery cell face each other is preferable.
Further, the back surface side protection member may be a translucent member.
In this case, since light also enters 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 particular, in this case, the solar cell is preferably a double-sided light-receiving solar cell.

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

The upper surface and the lower surface may be the upper surface and the lower surface 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.
As the first resin, for example, an epoxy-based resin or the like may be used. As the second resin, an average molecular weight is higher than that of the first resin so that elasticity is higher than that of the first resin. A large epoxy resin or urethane resin may be used.

  INDUSTRIAL APPLICABILITY The present invention can provide a solar cell provided with a collector electrode having good adhesion and a solar cell module using the solar cell.

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. It is a partial cross section figure of the solar cell module along A-A 'of FIG. 4 (a) is a top view of a solar battery cell used in the solar battery module according to the first embodiment of the present invention, FIG. 4 (b) is a back view of the solar battery cell, and FIG. 4 (c) 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 for demonstrating 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 to 3 mm and a thickness of 100 to 300 μm made of a 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. 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. Metal frame made of It is constructed from.
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 covered 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 conductivity on the other end side of other predetermined adjacent solar cell groups 7 and 7. , The thickness of the conductive connecting members 6, 6,... Is 0.5 mm to 3 mm and is made of a 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. Solder-connected to 100 to 300 μm L-shaped conductive connection 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).
With reference to FIG. 4 thru | or FIG. 6, the said photovoltaic cell 5 is a double-sided light reception type photovoltaic 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.
In the solar battery cell 1, a surface-side electrode 22 is formed on the transparent conductive film 18 by mixing and containing a reflective conductive material such as a metal material and a resin that functions as an adhesive.
The resin is a mixture of a main component resin and a subcomponent resin having an average molecular weight larger than that of the main component resin. The subcomponent resin is more elastic than the main component resin, and The resin absorbs less light in the visible light region than the subcomponent resin.
Here, the weight concentration of the reflective conductive material is higher than the weight concentration of the resin (the total weight concentration of the main component resin and the sub component resin), and the weight concentration of the main component resin is It is higher than the weight concentration of the component resin.
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 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, each of the bus bar electrodes 221b and 221b of the surface side electrode 22 has a width of 0.1 to 1.8 mm, for example, a 1.3 mm straight (band) electrode.
The surface-side electrode 22 includes a first layer 222a and a second layer 222b having different contents of the main component resin and the subcomponent resin of the first layer 222a in this order on the transparent conductive film 18. It is a two-layer structure laminated.
The content ratio of the resin in the first layer 222a (main component resin and subcomponent resin) and the reflective conductive material, and the resin in the second layer 222b (main component resin and subcomponent resin) The content ratio of the reflective conductive material is the same.
The first layer 222a on the transparent conductive film 18 side, which is the base, has a higher weight concentration of the sub-principal component resin than the second layer 222b on the front side cover 2 side (light incident side). The weight concentration of is low. Therefore, the second layer 222b on the surface side cover 2 side (light incident side) has a higher weight concentration of the main component resin than the first layer 222a on the transparent conductive film 18 side which is the base, and the subcomponent The resin weight concentration is low.
Moreover, the photovoltaic cell 1 has the back surface side electrode 23 formed by mixing a transparent conductive film 21 with a reflective conductive material such as a metal material and a resin functioning as an adhesive.
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 finger electrodes 231a, 231a,... Of the back surface 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 linear (band) electrode.
The back electrode 23 includes a first layer 232a and a second layer 232b having a different content of the main component resin and the subcomponent resin from the first layer 232a on the transparent conductive film 21 in this order. It is a two-layer structure formed by laminating.
The content ratio of the resin in the first layer 232a (main component resin and subcomponent resin) and the reflective conductive material, and the resin in the second layer 232b (main component resin and subcomponent resin) The content ratio of the reflective conductive material is the same.
The first layer 232a on the transparent conductive film 21 side that is the base has a higher weight concentration of the subcomponent resin than the second layer 232b on the back surface side cover 3 side (reverse light incident side), and the main component resin Low weight concentration. Therefore, the second layer 232b on the back surface side cover 3 side (reverse light incident side) has a higher weight concentration of the main component resin than the first layer 232a on the transparent conductive film 21 side which is the base, and the subcomponent The resin weight concentration is low.
In the present embodiment, an epoxy resin or a urethane resin having an average molecular weight larger than that of the epoxy resin is used so that elasticity is higher than that of the epoxy resin as an epoxy resin as a main component resin and a resin as a secondary component. Used.
The first layers 222a, 222a,... Of the front electrode 22 are flaky silver fine particles having a main resin content of 7 wt%, an auxiliary resin content of 3 wt%, and an average major axis of 5-20 μm. The content of the reflective conductive material formed by mixing the powder and spherical silver fine powder having an average particle size of 0.1 to 5 μm is 90 wt%.
In addition, the second layers 222b, 222b,... Of the surface-side electrode 22 are flakes having a main resin content of 9 wt%, a sub resin content of 1 wt%, and an average major axis of 5 to 20 μm. The content of the reflective conductive material obtained by mixing silver fine powder and spherical silver fine powder having an average particle diameter of 0.1 to 5 μm is 90 wt%.
In the present embodiment, the first layer 232a, 232a,... Of the back surface side electrode 23 has a main resin content of 7 wt%, an auxiliary resin content of 3 wt%, and an average major axis of 5 to 20 μm. The content of the reflective conductive material obtained by mixing the flaky silver fine powder and the spherical silver fine powder having an average particle diameter of 0.1 to 5 μm is 90 wt%.
The second layers 232b, 232b,... Of the back-side electrode 23 are flakes having a main resin content of 9 wt%, a sub resin content of 1 wt%, and an average major axis of 5 to 20 μm. The content of the reflective conductive material obtained by mixing fine silver powder and fine spherical silver powder having an average particle size of 0.1 to 5 μm is 90 wt%.
In addition, most of the flaky silver powder in the second layers 222b, 222b,... Of the front side electrode 22 and the second layers 232b, 232b,. Oriented parallel to the layer.
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.
As described above, in this embodiment, the subcomponent resin is the main component resin so that the elasticity of the subcomponent resin is greater than that of the main component resin, and the main component resin has less light absorption than the subcomponent resin. The average molecular weight is larger than that of the component resin.
Therefore, since the surface side electrode 22 includes more of the second layer 222b, 222b,..., The sub-component resin having higher elasticity in the first layer 222a, 222a,. Since stress caused by the difference in thermal expansion coefficient between the inner surface side electrode 22 and the substrate 15 is relieved, the adhesiveness between the surface side electrode 22 and the transparent conductive film 18 as a base is increased, and the reliability is improved. improves.
In addition, since the back-side electrode 23 includes more of the second layer 232b, 232b,..., The first layer 232a, 232a,. Since the stress caused by the difference in thermal expansion coefficient between the back surface side electrode 23 and the substrate 15 in the layer is relieved, the adhesiveness between the back surface side electrode 23 and the transparent conductive film 21 as a base is increased, and reliability is increased. Will improve.
In addition, the surface-side electrode 22 includes the second layer 222b, 222b,... On the upper surface side containing a smaller amount of sub-component resin with high light absorption than the first layers 222a, 222a,. The light reflectance of the upper surface or upper side surface of the electrode 22 can be increased.
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.
In addition, since the back surface side electrode 23 includes the second layers 232b, 232b,... On the upper surface side less than the second layers 232a, 232a,. The light reflectance of the upper surface or upper side surface of the side electrode 23 can be increased.
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 electrode 22 and 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 a direction parallel to the second layers 222b, 222b, 232b, 232,. The output of the solar battery cell 5 is further improved.
Further, in the present embodiment, the main component resin has weather resistance and / or moisture resistance as compared with the subcomponent resin, and the second layer 222b of the front surface side electrode 22 and the second layer of the rear surface side electrode 23 are provided. Since the layer 232b contains more of the main component resin than the first layer 222a of the front-side electrode 22 and the first layer 232a of the back-side electrode 23, even when used for a long time under high temperature and high humidity conditions, Deterioration of the electrode 22 and the back surface side electrode 23 can be prevented, and the reliability is improved.
(Method for manufacturing solar cell module)
Below, the manufacturing method of the solar cell module which concerns on this embodiment is demonstrated.
First, the photovoltaic cell 5 provided with the transparent electrode film layers 18 and 21 on both surfaces is prepared.
Next, a first conductive paste and a second conductive paste in which a predetermined amount of a reflective conductive material is dispersed in a paste in which a predetermined amount of a main component resin and a subcomponent resin are dissolved in a solvent. prepare. Here, in the second conductive paste, the weight concentration of the subcomponent resin is lower than that of the main component resin, as compared with 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. The first conductive paste is printed on the transparent conductive layer 21 of the solar battery cell 5 by screen printing, offset printing, pad printing, etc. Is printed in a predetermined pattern and dried, and then 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 the second layer 222b, 222b,..., And the back surface side electrode of the front surface side electrode 22 using screen printing, offset printing plate, pad printing plate, or the like. Since the second layers 232b, 232b,... 23 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 2 and the back side cover 3 are both translucent members.
In addition, the solar cell module 1 of the present embodiment is a double-sided light receiving solar cell module, and since the back cover 3 is made of glass or the like, the terminal box 14 is provided in the vicinity of the frame body 8 in order to reduce the light shielding loss. The output connection connecting members corresponding to the connection members 10, 11, 12, and 13 drawn out from the front cover 2 and the back cover 3 are led into the terminal box 14.
In the solar cell module of the present embodiment, the same effects as those of the first embodiment can be obtained, and light can also be incident from the back surface side cover 3. Of the light incident from the back surface side cover 3, the back surface side electrode 23. Since the light reaching the upper surface and upper side surface, that is, the second layers 232b, 232b,... Is efficiently reflected by the upper surface and the upper side surface, it is re-reflected by the back surface side cover 3 or the filler 4. As a result, a large amount of light is incident on the solar battery cell 5 and, as a result, 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 the present embodiment, the same effects as those in the first embodiment can be obtained with respect to the surface-side electrode 22.
(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,. In addition, the second layers 252b, 252b,... Of the back-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 and description thereof is omitted.
In FIG. 7, the first layers 242a, 242a,... Of the surface-side electrode 22 are covered with the second layers 242b, 242b,. That is, the portion that is exposed to light is configured to be the second layers 242b, 242b,.
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,.
In the present embodiment, the weight concentration of the subcomponent resin contained in the first layers 242a, 242a,... Of the surface side electrode 22 is made larger than that of the second layers 242b, 242b,. The weight concentration of the subcomponent resin contained in the second layers 242b, 242b,... Covering the first layers 242a, 242a,... Is smaller than that of the first layers 242a, 242a,. Therefore, the light reflection of the surface side electrode 22 can be increased while strengthening the adhesion of the surface side electrode 22 to 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, and the output of the solar cell 5 is improved.
Further, the first layer 252a, 252a,... Of the back-side electrode 23 is made so that the weight concentration of the subcomponent resin contained therein is larger than that of the second layers 252b, 252b,. Since the weight concentration of the subcomponent resin contained in the second layers 252b, 252b,... Covering the 252a, 252a,... Is smaller than that of the first layers 252a, 252a,. The light reflection of the back surface side electrode 23 can be increased while strengthening the adhesion of the 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 on 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 increases, and as a result, a large amount of light is applied to the solar cells 5 also on the back surface side. Since it injects, the output of the photovoltaic cell 5 improves more.
In the present embodiment, the main component resin has weather resistance and moisture resistance as compared to the sub component resin, and the front side electrode 22 has a second layer 242b covering the first layer 242a, and the back side. In the electrode 23, since the second layer 252b covering the first layer 252a contains a large amount of resin as a main component, the deterioration of the front side electrode 22 and the back side electrode 23 even when used for a long time under high temperature and high humidity conditions. Can be prevented and reliability 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 can be 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.
As for the bus bar electrodes 221b, 221b, 231b, and 23 of the front surface side electrode 22 and the back surface side electrode 23, the second layers 242b, 252b, and so on may cover the first layers 242a, 252a, and so on.
The front surface side electrode 22 and the back surface side electrode 23 of the solar battery cell 5 of this embodiment can also be produced using the first and second conductive pastes, for example, as in the first embodiment. In this case, screen printing plates, offset printing plates, pad printing plates, etc. for the second layers 242b, 242b, 252b, 252b,... Are screens for the first layers 242a, 242a, 252a, 252a,. A plate having a pattern width of about 10 μm larger than that of a plate, offset printing plate, 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-side electrode 23 does not have the second layers 252b, 252b,..., But includes the first layers 252a, 252a,. 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 the present embodiment, the same effects as those in the fourth embodiment can be obtained with respect to the surface-side electrode 22.
In each of the above embodiments, the first layer and the second layer of the front surface side electrode 22 and the first layer and the second layer of the back surface side electrode 23 contain two types of resins. It can be applied to those containing a plurality of types of resins. Further, the resin contained in the first layer and the second layer may be one kind of resin.
Moreover, although the surface side electrode 22 and the back surface side electrode 23 of said each embodiment are 2 layer structures of a 1st layer and a 2nd layer, it may be comprised not only in this but in multiple layers. In this case, the weight concentration of the main component resin whose average molecular weight is smaller than that of the subcomponent resin is higher in the uppermost layer than that of the lowermost layer, and the weight concentration of the subcomponent resin whose average molecular weight is higher than that of the main component resin is the highest. The lower layer may be made higher than the uppermost layer. Furthermore, the weight concentration of the main component resin having an average molecular weight smaller than that of the subcomponent resin is higher on the upper side of the uppermost layer than the lower side of the lowermost layer, and the weight concentration of the subcomponent resin is higher than that of the main component resin. The weight concentration may be higher on the lower side of the lowermost layer than on the upper side of the uppermost layer.
Further, the front-side electrode 22 and the back-side electrode 23 may have a configuration without a layer structure, or a configuration with only one layer. In this case, the weight concentration of the main component resin whose average molecular weight is smaller than that of the subcomponent resin is higher on the upper side than that of the lower side, and the weight concentration of the subcomponent resin whose average molecular weight is higher than that of the main component resin is lower on the lower side. What is necessary is just to make it high compared with the upper side. Furthermore, the weight concentration of the main component resin whose average molecular weight is smaller than that of the subcomponent resin is gradually increased from the lower side toward the upper side, and the subcomponent resin whose average molecular weight is larger than that of the main component resin. The weight concentration may be gradually increased from the upper side toward the lower side.
Further, in each of the above embodiments, the content ratio of the resin in the first layer (main component resin and subcomponent resin) and the reflective conductive material and the resin in the second layer (main component resin and subcomponent resin). The content ratio of the component resin) and the reflective conductive material was the same, but they may be different. In that case, it is preferable to increase the content ratio of the resin in the first layer and increase the content ratio of the reflective conductive material in the second layer.
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.
Moreover, in each said embodiment, although this invention was applied to both the finger electrode and bus-bar electrode of the surface side electrode 22 and / or the back surface side electrode 23, you may apply only to a 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.
Further, 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, examples of the method for producing the front surface side electrode 22 and the back surface side electrode 23 of the solar cell module include screen printing, offset printing, and pad printing.

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 (4)

A solar cell comprising a first surface, a second surface, and a collector electrode formed on the first surface, wherein the collector electrode contains at least a reflective conductive material and a resin. The resin comprises at least a first resin and a second resin having higher elasticity than the first resin, and the weight concentration of the second resin in the collector electrode is such that the first surface side has the collector. A solar cell characterized by being higher than the upper surface side of the electrode. The solar cell according to claim 1, wherein the second resin has an average molecular weight larger than that of the first resin.   The said collector electrode consists of two or more layers, The weight density | concentration of the said 2nd resin is higher than the uppermost layer of this plurality of layers in the lowest layer of these multiple layers, The 1st or 2 characterized by the above-mentioned. Solar cells. It is a solar cell module provided with the photovoltaic cell as described in any one of Claims 1 thru | or 3, 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.

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