KR20140056524A - Solar cell - Google Patents

Abstract

A solar cell of the present invention includes a substrate; an emitter part which is located in a first surface of the substrate and forms the p-n junction with the substrate; a first electrode part which is located in the first surface of the substrate and is connected to the emitter part; a second electrode part which is located on a second surface of the substrate which is opposite to the first surface and is connected to the substrate. The first electrode part includes first finger electrodes which are extended in a first direction. The first finger electrodes are separated from adjacent finger electrode. A diffused reflection coating layer is formed on the upper surface of the first finger electrodes.

Description

Solar cell {SOLAR CELL}

The present invention relates to a solar cell.

Recently, as energy resources such as petroleum and coal are expected to be depleted, interest in alternative energy to replace them is increasing, and solar cells that produce electric energy from solar energy are attracting attention.

A typical solar cell has a substrate and an emitter layer each of which is made of a semiconductor of a different conductive type such as a p-type and an n-type, and electrodes respectively connected to the substrate and the emitter. At this time, a p-n junction is formed at the interface between the substrate and the emitter.

When light is incident on such a solar cell, electrons in the semiconductor become free electrons (hereinafter referred to as 'electrons') due to a photoelectric effect, and electrons and holes are attracted to n Type semiconductor and the p-type semiconductor, for example, toward the emitter portion and the substrate, respectively. And the transferred electrons and holes are collected by the respective electrodes electrically connected to the substrate and the emitter portion.

An electrode located on the incident side of the substrate on which the light is incident has a light absorption area of the substrate. Most of the light incident on the electrode at an incident angle of 0 DEG, that is, vertically, is regularly reflected at the electrode surface, .

In order to suppress such a problem, a method of forming a light scattering pattern on a front substrate of a portion where electrodes are disposed has been proposed. However, in order to form a light scattering pattern, alignment work is necessary, There is a problem.

SUMMARY OF THE INVENTION The present invention provides a solar cell with improved efficiency.

A solar cell according to an embodiment of the present invention includes a substrate; An emitter located on a first side of the substrate and forming a p-n junction with the substrate; A first electrode part located on a first surface of the substrate and connected to the emitter part; And a second electrode portion located on a second surface of the substrate opposite to the first surface and connected to the substrate, wherein the first electrode portion includes a plurality of first finger electrodes extending in a first direction, The first finger electrodes are spaced apart from adjacent first finger electrodes, and a diffusive coating film is formed on the upper surface of the first finger electrodes.

The plurality of first finger electrodes may be formed in a non-bus structure that is not physically connected to the neighboring first finger electrodes.

That is, in the solar cell having the first finger electrodes of the non-bus structure, the first finger electrodes of the line shape are arranged on the first surface of the substrate so as to be spaced apart from each other with a predetermined interval, And is electrically connected only by the connector and the emitter portion.

In this case, each first finger electrode includes a first region where the interconnector is bonded and a second region other than the first region.

The second region is integrally connected to the second region in the first direction, and the diffusely reflective coating film is formed only on the upper surface of the second region.

The width of the diffusely reflective coating film is equal to the width of the first finger electrode or smaller than the width of the first finger electrode.

The number of the second regions of the first finger electrode is one more than the number of the first regions.

The second electrode portion located on the second surface of the substrate includes a plurality of second finger electrodes extending in the first direction and the plurality of second finger electrodes are formed in a non-bus structure like the plurality of first finger electrodes .

Accordingly, the plurality of second finger electrodes are formed in a line shape, are spaced apart from each other by a predetermined distance from adjacent second finger electrodes, and the adjacent second finger electrodes are electrically connected only by the interconnector.

And when the rear electric field portion is located on the second surface of the substrate, the adjacent second finger electrodes are electrically connected only by the interconnector and the rear electric field portion.

At this time, each of the second finger electrodes includes a first region where the interconnector is bonded and a second region other than the first region, and the diffuse reflection coating film is formed only on the lower surface of the second region.

The width of the diffusely reflective coating film may be equal to or smaller than the width of the second finger electrode and the number of the second regions of the second finger electrode may be one more than the number of the first regions do.

Alternatively, the second electrode part may include a plurality of second bus bar electrodes extending in a second direction intersecting the first direction, and a plurality of second bus bar electrodes formed on the sheet, Two electrodes may be included.

The first electrode unit may further include a first bus bar electrode extending in a second direction intersecting the first direction and physically connecting the plurality of first finger electrodes to adjacent first finger electrodes.

That is, in the first electrode part of the non-bus structure, the first finger electrodes are electrically connected by the emitter part and the inter connector, but in the first electrode part including the first bus bar electrode, the emitter part and the first bus bar electrode The first finger electrodes are electrically connected.

At this time, an interconnector is bonded to the first bus bar electrode, and a diffusely reflective coating film is formed on the entire upper surface of the first finger electrodes.

The width of the diffusely reflective coating may be the same as the width of the first finger electrode or less than the width of the first finger electrode.

As with the first electrode unit, the second electrode unit includes a plurality of second finger electrodes extending in a first direction and a plurality of second finger electrodes extending in a second direction intersecting the first direction, And a second bus bar electrode that is physically connected to the second bus bar electrode.

At this time, the second bus bar electrode is bonded to the interconnector, and the diffusely reflective coating film may be formed on the entire lower surface of the second finger electrodes.

The width of the diffused reflection coating may be equal to the width of the second finger electrode or smaller than the width of the second finger electrode.

Alternatively, the second electrode part may include a plurality of second bus bar electrodes extending in a second direction intersecting the first direction, and a plurality of second bus bar electrodes formed on the sheet, Two electrodes may be included.

According to this feature, the incident angle of 0 °, that is, most of the light incident on the finger electrode in the vertical direction is irregularly reflected by the diffuse reflection coating film formed on the surface of the finger electrode, the diffused reflection is reflected again from the inner surface of the front substrate, do.

Accordingly, the amount of light incident on the substrate increases, thereby increasing the efficiency of the solar cell.

1 is an exploded perspective view of a solar cell module according to an embodiment of the present invention.
2 is a side view showing an electrical connection structure of the solar cell module.
3 is a perspective view of a main part of a solar cell according to the first embodiment of the present invention.
4 is a perspective view of a main part of a solar cell according to a second embodiment of the present invention.
5 is a perspective view of a main part of a solar cell according to a third embodiment of the present invention.
6 is a perspective view of a main portion of a solar cell according to a fourth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention in the drawings, portions not related to the description are omitted, and like reference numerals are given to similar portions throughout the specification.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. When a layer, film, region, plate, or the like is referred to as being "on" another portion, it includes not only the case directly above another portion but also the case where there is another portion in between. Conversely, when a part is "directly over" another part, it means that there is no other part in the middle.

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view of a solar cell module according to an embodiment of the present invention, and FIG. 2 is a side view illustrating an electrical connection structure of the solar cell module.

Referring to the drawings, a solar cell module includes a plurality of solar cells 10, an interconnector 20 for electrically connecting adjacent solar cells 10, a protective film (EVA: Ethylene Vinyl A front substrate 40 disposed on the protective film 30a toward the front side of the solar cells 10 and a rear substrate disposed below the protective film 30b toward the rear side of the solar cells 10, A back sheet 50, a frame (not shown) for housing the components integrated by the lamination process, and a junction box (not shown) for finally collecting the current and voltage produced by the solar cells 10 junction box, not shown).

The front substrate 40 is made of tempered glass or the like having high transmittance and excellent breakage preventing function. At this time, the tempered glass may be a low iron tempered glass having a low iron content. The inner surface of the front substrate 40 may be embossed in order to enhance the light scattering effect.

The rear substrate 50 protects the solar cells 10 from the external environment by preventing moisture from penetrating the rear surface of the solar cell module. Such a backside substrate 50 may have a multi-layer structure such as a layer preventing moisture and oxygen penetration, a layer preventing chemical corrosion, and a layer having an insulating property.

Like the front substrate 40, the rear substrate 50 may be formed of a light-transmissive glass material or a resin material. Alternatively, the rear substrate 50 may be formed of an opaque material.

The protective films 30a and 30b positioned between the front substrate 40 and the rear substrate 50 are integrated with the solar cells 10 by the lamination process while being disposed on the front and rear surfaces of the solar cells 10, Preventing corrosion due to moisture penetration, and protecting the solar cells 10 from impact.

The protective films 30a and 30b may be made of a material such as ethylene vinyl acetate (EVA) or silicone resin.

The solar cell module includes a step of testing the solar cells 10, a step of electrically connecting the plurality of tested solar cells 10 by the interconnector 20, the step of sequentially connecting the components to the rear substrate (30), a protection film (30a) and a front substrate (40) in this order, a step of performing a lamination process in a vacuum state to integrate the components, an edge trimming edge trimming step, and module testing step.

A plurality of solar cells 10 are arranged in a matrix structure as shown in FIG. In FIG. 1, the solar cell 10 arranged on the protective film 130b has a 3 × 3 matrix structure, but the number of the solar cells 10 arranged in the row and column directions is not limited to this, It is possible.

The first electrode portion formed on the front surface of one solar cell 10 is connected to the second electrode portion formed on the rear surface of another adjacent solar cell 10 and the second electrode portion formed on the rear surface of the adjacent solar cell 10, 20).

For example, when bisecting the interconnector 20 in the lengthwise direction, one end of the interconnector 20 is connected to the first electrode portion formed on the front surface of one solar cell 10, and the other end of the interconnector 20 is connected to another adjacent solar cell 10 And is joined to the second electrode portion formed on the rear surface. According to this connection method, a plurality of solar cells are connected in series.

The interconnect 20 includes a conductive metal portion. The conductive metal part may be made of any one of Cu, Al, and Ag, which is excellent in conductivity.

Hereinafter, the configuration of a solar cell according to an embodiment of the present invention will be described in detail.

3 is a perspective view of a solar cell according to a first embodiment of the present invention, showing a non-bus solar cell in which a first electrode portion positioned on a front surface of the solar cell has no bus bar.

The solar cell 10 according to the first embodiment includes a substrate 110, a first surface of the substrate 110, for example, an emitter section 120, a emitter section 120, A first dielectric layer 140 located on the emitter section 120 where the plurality of first finger electrodes 131 are not located and a second dielectric layer 140 on the opposite side of the light receiving surface, And a second electrode unit 150 positioned on a second surface of the substrate 110.

The solar cell 10 may further include a back surface field (BSF) unit 160 formed between the second electrode unit 150 and the substrate 110. The rear electric field 160 is a region in which impurities of the same conductivity type as that of the substrate 110 are doped at a higher concentration than the substrate 110, for example, a p + region.

This rear electric field 160 reduces recombination between electrons and holes at the rear side of the substrate 110 to disappear.

The substrate 110 is a semiconductor substrate of a first conductivity type, for example, silicon of p-type conductivity type. The silicon may be monocrystalline silicon, polycrystalline silicon or amorphous silicon. When the substrate 110 has a p-type conductivity type, it contains an impurity of a trivalent element such as boron (B), gallium (Ga), indium (In)

The surface of the substrate 110 may be formed with a texturing surface having a plurality of irregularities.

When the surface of the substrate 110 is formed as a textured surface, the light reflection on the light receiving surface of the substrate 110 is reduced, and the incidence and reflection operations are performed on the textured surface, so that light is trapped inside the solar cell, do.

Thus, the efficiency of the solar cell is improved. In addition, since the reflection loss of light incident on the substrate 110 is reduced, the amount of light incident on the substrate 110 is further increased.

The emitter portion 120 is a region doped with an impurity having a second conductivity type opposite to the conductivity type of the substrate 110, for example, an n-type conductivity type. The substrate 110 and the pn Junction.

When the emitter section 120 has an n-type conductivity type, the emitter section 120 dopes impurities of pentavalent elements such as phosphorus (P), arsenic (As), antimony (Sb) .

Accordingly, when electrons in the semiconductor are energized by the light incident on the substrate 110, the electrons move toward the n-type semiconductor and the holes move toward the p-type semiconductor. Therefore, when the substrate 110 is p-type and the emitter section 120 is n-type, the separated holes move toward the substrate 110, and the separated electrons move toward the emitter section 120.

Conversely, the substrate 110 may be of the n-type conductivity type and may be made of a semiconductor material other than silicon. When the substrate 110 has an n-type conductivity type, the substrate 110 may contain impurities of pentavalent elements such as phosphorus (P), arsenic (As), antimony (Sb), and the like.

Since the emitter section 120 forms a p-n junction with the substrate 110, when the substrate 110 has an n-type conductivity type, the emitter section 120 has a p-type conductivity type. In this case, the separated electrons move toward the substrate 110 and the separated holes move toward the emitter part 120.

When the emitter section 120 has a p-type conductivity type, the emitter section 120 is formed by doping an impurity of a trivalent element such as boron (B), gallium (Ga), indium (In) .

A first dielectric layer 140 including at least one layer made of a silicon nitride (SiNx), a silicon oxide (SiO ₂ ), or a titanium dioxide (TiO ₂ ) is formed on the emitter 120 of the substrate 110, Respectively.

The first dielectric layer 140 may function as an antireflection film for reducing the reflectivity of light incident on the solar cell 10 and increasing the selectivity of a specific wavelength region to enhance the efficiency of the solar cell 10.

Alternatively, the first dielectric layer 140 may function as a passivation film, and may simultaneously perform functions of an antireflection film and a passivation film, if necessary.

The plurality of first finger electrodes 131 are formed in a line shape and are formed on the emitter section 120 and are electrically and physically connected to the emitter section 120. The first finger electrodes 131 are spaced apart from the first finger electrodes 131, In one direction.

The solar cell of this embodiment has no bus bar electrode that physically and electrically connects the first finger electrodes 131 so that the first finger electrodes 131 are electrically connected only by the interconnector 20 and the emitter unit 120 do.

Each of the first finger electrodes 131 collects electrons, for example, electrons, which have migrated toward the emitter section 120.

The plurality of first finger electrodes 131 are made of at least one conductive material, and the conductive materials may be at least one selected from the group consisting of Ni, Cu, Ag, Al, Sn, Zn), indium (In), titanium (Ti), gold (Au), and combinations thereof, but may be made of other conductive metal materials.

For example, the first finger electrode 131 may be made of a silver (Ag) paste containing lead (Pb). In this case, the first finger electrode 131 is formed by applying a silver paste onto the first dielectric layer 140 using a screen printing process and firing the substrate 110 at a temperature of about 750 ° C to 800 ° C And may be electrically connected to the emitter section 120 at the same time.

At this time, the above-mentioned electrical connection is made by the lead component contained in the silver (Ag) paste in the firing process, by etching the first dielectric layer 140 so that the silver (Ag) particles come into contact with the emitter section 120.

Each of the first finger electrodes 131 includes a first area A1 to which the interconnector 20 is bonded and a second area A2 other than the first area A1.

The second region A2 is integrally connected to the first region A1 in the first direction X-X ', and the diffusive coating film 170 is formed on the upper surface of the second region A2.

The anti-reflective coating layer 170 may be formed of a composition including a mixed liquid in which a homogeneous or heterogeneous nano powder having different particle size distributions are uniformly dispersed in an amphoteric solvent and a binder component.

The mixing ratios of the homogeneous or heterogeneous nano powders having different particle size distributions are obtained by dividing the nano powder having the maximum average particle size distribution by the bisector or the third portion and then mixing the nano powder having the average particle size distribution corresponding to each part As shown in FIG.

At this time, a material having a higher particle size of the nanopowder may be arranged as a material having higher transparency, and a material having a smaller particle size of the nanopowder may be used as a material having a lower transmittance.

The nano powder may be included in an amount of 0.001% by weight to 20% by weight based on the total weight% of the composition.

Nano-powder of silica (SiO _2), alumina (Al ₂ o _3), magnesium oxide (MgO), titanium dioxide (TiO _2), zirconia (ZrO _2), zinc (ZnO), indium oxide (In ₂ O ₃₎ , Tin oxide (SnO ₂ ), antimony oxide (Sb ₂ O ₅ ), and zinc sulfide (ZnS).

The amphoteric solvent may be selected from the group consisting of dimethylformamide, dimethylacetamide, dimethylsulfoxide, hexamethylphosphoric acid triamide, diethylacetamide, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol mono Butyl ether.

The anti-reflective coating 170 may be formed of a semi-transparent film, and the particle size of the nano powder may be controlled according to the wavelength band to be reflected. At this time, the particle size of the nano powder can be selected to be about 0.5 times the wavelength to be reflected.

The diffusive reflective coating 170 having such a configuration may be coated on the upper surface of the second area A2 of the first finger electrode 131 by a paint method or a spray method.

Alternatively, the anti-reflective coating 170 may be made in the form of a tape and then attached to the upper surface of the second area A2 by a tape adhering method.

The width of the diffusely reflective coating 170 is equal to the width of the first finger electrode 131 or smaller than the width of the first finger electrode 131. Here, the "width" means a width measured in a second direction (Y-Y ') orthogonal to the first direction (X-X').

The number of the second regions A2 of the first finger electrodes 131 is one more than the number of the first regions A1.

The second electrode unit 150 is formed on a second surface of the substrate 110 and includes a plurality of second bus bar electrodes 161 extending in a second direction Y-Y 'intersecting the first direction X- And a second electrode 151 on a sheet that covers the rear surface of the substrate except the portion where the first bus bar electrode 153 and the second bus bar electrode 153 are formed.

The sheet-like second electrode 151 is made of at least one conductive material. The conductive material may be at least one selected from the group consisting of Ni, Cu, Ag, Al, Sn, Zn, In, Ti, Au, And combinations thereof, but may be made of other conductive materials.

The second bus bar electrode 153 is also made of at least one conductive material and is electrically connected to the second electrode 151. Accordingly, the second bus bar electrode 153 outputs the charge, for example, holes, transmitted from the second electrode 151 to an external device.

The conductive metal material constituting the second bus bar electrode 153 may be at least one selected from the group consisting of Ni, Cu, Ag, Al, Sn, Zn, And may be at least one selected from the group consisting of titanium (Ti), gold (Au), and combinations thereof, but may be made of other conductive metal materials.

The second electrode 151 may be formed of aluminum (Al) in order to form the rear electric section 160 on the second surface of the substrate 110, and the first finger electrode 131 and the second bus bar electrode (Ag) having good conductivity can be formed.

The solar cell 10 having such a configuration is electrically connected to the neighboring solar cell by the interconnector 20.

More specifically, a plurality of conductive adhesive films ((Y-Y ')) are formed on the emitter section 120 of the substrate 110 in a direction crossing the plurality of first finger electrodes 131, 60).

Although FIG. 3 shows only one conductive adhesive film 60, two or three conductive adhesive films 60 may be positioned on the first and second surfaces of the substrate 110, respectively.

The conductive adhesive film 60 is formed in a film shape in which a plurality of conductive particles are dispersed in a resin.

The resin is not particularly limited as long as it is a material having adhesiveness. However, in order to improve adhesion reliability, it is preferable to use a thermosetting resin.

As the thermosetting resin, at least one resin selected from an epoxy resin, a phenoxy resin, an acryl resin, a polyimide resin, and a polycarbonate resin may be used.

The resin may contain a known curing agent and a curing accelerator as optional components other than the thermosetting resin.

For example, the resin may be a silane-based coupling agent, a titanate-based coupling agent, or an aluminate-based coupling agent for improving the adhesiveness between the electrode portions 131 and 153 and the interconnector 20 aluminate-based coupling agent, and may contain a dispersing agent such as calcium phosphate or calcium carbonate in order to improve the dispersibility of the conductive particles. Further, the resin may contain rubber components such as acrylic rubber, silicone rubber, and urethane in order to control the modulus of elasticity.

The conductive particles are not particularly limited as long as they have conductivity. The conductive particles may be selected from the group consisting of copper (Cu), silver (Ag), gold (Au), iron (Fe), nickel (Ni), lead (Pb), zinc (Zn), cobalt (Co), titanium Mg) as a main component, and may be composed of only metal particles or metal coated resin particles. The conductive adhesive film 60 having such a configuration may further include a release film.

In order to alleviate the compressive stress of the conductive particles and improve the connection reliability, it is preferable to use the metal-coated resin particles as the conductive particles.

In order to improve the dispersibility, the conductive particles preferably have a particle diameter of 2 mu m to 30 mu m.

From the viewpoint of the connection reliability after the resin is cured, the amount of the conductive particles dispersed in the resin is preferably 0.5 volume% to 20 volume% with respect to the total volume of the conductive adhesive film 60. [

If the blending amount of the conductive particles is less than 0.5% by volume, the physical contact point with the electrode parts 131 and 153 is reduced, and current flow may not be smooth. When the blending amount exceeds 20% by volume, The adhesive strength may be lowered.

The conductive adhesive film 60 is bonded to the first region A1 of the first finger electrode 131 in a direction crossing the plurality of first finger electrodes 131. [ Thus, a part of the conductive adhesive film 60 is in direct contact with the upper surface of the first area A1, and the remaining part is in direct contact with the anti-reflection film 140. [

The conditions of the heating temperature and the pressing pressure are not particularly limited as long as the electrical connection and the adhesive force can be maintained when tabbing is performed using the conductive adhesive film 60. [

For example, the heating temperature can be set within a temperature range in which the resin is cured, for example, in the range of 150 to 180 DEG C. The pressing pressure is applied to the electrode portions 131 and 153, the conductive adhesive film 60, Can be set in a range in which they are sufficiently close to each other. The heating and pressurizing time can be set within a range in which the electrode parts 131 and 153 and the interconnector 20 are not damaged or deteriorated due to heat.

4 is a perspective view of a solar cell according to a second embodiment of the present invention. The remaining structure except for the second electrode portion and the rear electric field portion formed on the second surface of the substrate 110 is the same as that shown in FIG. 3 The structure of the second electrode portion and the rear surface electric field portion will be described below.

In the following description of the embodiment, the same constituent elements as those of the first embodiment are given the same reference numerals, and a detailed description thereof will be omitted.

A second dielectric layer 180 is formed on the second surface of the substrate 110 and a plurality of second finger electrodes 155 are formed on the second surface of the region where the second dielectric layer 180 is not formed.

The plurality of second finger electrodes 155 are formed in a line shape extending in the first direction X-X 'like the first finger electrodes 131, and are spaced apart from the adjacent second finger electrodes 155 by a predetermined distance Respectively. Therefore, the adjacent second finger electrodes 155 are electrically connected only by the interconnector.

The second finger electrode 155 includes a first region where the interconnector 20 is bonded and a second region other than the first region in the same manner as the first finger electrode 131, The anti-reflective coating film 170 is formed.

As described above, in the solar cell of the present embodiment, the first electrode portion located on the first surface of the substrate 110 is composed only of the first finger electrodes 131, and the second electrode portion located on the second surface of the substrate 110 And only the second finger electrodes 155 are formed.

Therefore, unlike the solar cell of the first embodiment, the solar cell of the present embodiment can be used as a double-sided light receiving solar cell because light can be incident through the first and second surfaces of the substrate, respectively.

On the other hand, in the case of the double-sided light receiving type solar cell, the amount of light incident through the first surface of the substrate 110 is larger than the amount of light incident through the second surface, The number of the second finger electrodes 155 may be larger than the number of the second finger electrodes 155. In this case, the interval between the second finger electrodes 155, that is, the pitch may be smaller than the interval between the first finger electrodes 131.

The first embodiment of FIG. 3 and the second embodiment of FIG. 4 described above are solar cells in which the first electrode portion has a non-bus structure.

However, the present invention can also be applied to a case where the first electrode portion has a bus bar electrode. Hereinafter, a solar cell according to another embodiment of the present invention will be described with reference to FIGS. 5 and 6. FIG.

5 is a perspective view of a solar cell according to a third embodiment of the present invention. The remaining configuration except for the configuration of the first electrode portion formed on the first surface of the substrate 110 is the same as that of the first embodiment shown in FIG. 3 Only the configuration of the first electrode portion will be described below.

As shown in the figure, the solar cell of the present embodiment includes a first electrode unit 130 having a plurality of first finger electrodes 131 and at least two first bus bar electrodes 133.

Here, the first bus bar electrode 133 extends in the second direction Y-Y 'to electrically and physically connect the plurality of first finger electrodes 131.

The first bus bar electrode 133 may be formed of the same material as the first finger electrode 131, for example, silver (Ag).

Since the inter connecter 20 is bonded to the first bus bar electrode 133 by the conductive adhesive film 60 in the first electrode unit 130 having such a structure, The anti-reflective coating film 170 is not formed. The anti-reflection coating 170 is formed on the entire upper surface of the first finger electrodes 131.

5, the thickness of the first bus bar electrode 133 is slightly larger than the thickness of the first finger electrode 131 and the thickness of the first finger electrode 131 plus the thickness of the diffusely reflective coating film 17 is greater than the first The thickness of the first bus bar electrode 133 may be larger than the sum of the thickness of the first finger electrode 131 and the thickness of the diffusive coating film 17, have.

6 is a perspective view of the solar cell according to the fourth embodiment of the present invention. The remaining structure except for the configuration of the second electrode portion and the rear electric field portion located on the second surface of the substrate 110 is the same as that of the above- Therefore, only the configurations of the second electrode portion and the rear surface electric field portion will be described below.

As shown in the figure, the solar cell of this embodiment includes a second electrode unit 150 having a plurality of second finger electrodes 155 and at least two second bus bar electrodes 153.

Here, the second bus bar electrode 153 extends in the second direction Y-Y 'and electrically and physically connects the plurality of second finger electrodes 155.

The second bus bar electrode 153 may be formed of the same material as the second finger electrode 155, for example, silver (Ag) or an alloy of silver and aluminum (AgAl).

Unlike the rear electric field portion shown in the second embodiment of FIG. 4, the rear electric field portion 160 is locally formed on the rear surface of the substrate 110. FIG.

Here, the fact that the rear electric field portion is formed locally does not mean that the rear electric field portion is not formed in the entire area of the second surface of the substrate 110 as in the embodiment of Fig. 4, but a part of the second surface, Electrode 155 and the second bus bar electrode 153, respectively. Thus, a region of the substrate 110 is positioned between adjacent backside electrical sections 160.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (17)

Board;
An emitter located on a first side of the substrate and forming a pn junction with the substrate;
A first electrode part located on a first surface of the substrate and connected to the emitter part;
A second electrode located on a second surface of the substrate opposite to the first surface and connected to the substrate,
/ RTI >
Wherein the first electrode portion includes a plurality of first finger electrodes extending in a first direction, the plurality of first finger electrodes are spaced apart from adjacent first finger electrodes, Is formed. The method of claim 1,
Wherein the plurality of first finger electrodes are not physically connected to neighboring first finger electrodes. 3. The method of claim 2,
Wherein each of the first finger electrodes includes a first region where the interconnector is bonded and a second region except the first region, and the diffusely reflective coating film is formed only on the upper surface of the second region. 4. The method of claim 3,
Wherein the width of the diffusely reflective coating film is equal to or smaller than the width of the first finger electrode. 4. The method of claim 3,
Wherein the number of the second regions of the first finger electrodes is one more than the number of the first regions. The method according to any one of claims 2 to 5,
Wherein the second electrode portion includes a plurality of second finger electrodes extending in the first direction, the plurality of second finger electrodes are spaced apart from adjacent second finger electrodes, and the lower surface of the second finger electrodes has diffused reflection A solar cell in which a coating film is formed. The method of claim 6,
Wherein each of the second finger electrodes includes a first region where the interconnector is bonded and a second region except for the first region, and the diffusely reflective coating film is formed only on the lower surface of the second region. 8. The method of claim 7,
Wherein the width of the diffusely reflective coating film is equal to or smaller than the width of the first finger electrode. 9. The method of claim 8,
Wherein the number of the second regions of the second finger electrodes is one more than the number of the first regions. The method according to any one of claims 2 to 5,
The second electrode portion includes a plurality of second bus bar electrodes extending in a second direction intersecting the first direction and a plurality of second bus bar electrodes formed on a sheet on the rear surface of the substrate except the portion where the second bus bar electrodes are formed, A solar cell comprising two electrodes. The method of claim 1,
Wherein the first electrode portion further comprises a first bus bar electrode extending in a second direction intersecting the first direction and physically connecting the plurality of first finger electrodes to adjacent first finger electrodes. 12. The method of claim 11,
Wherein the first bus bar electrode is connected to an interconnector and the diffusely reflective coating film is formed on the entire upper surface of the first finger electrodes. The method of claim 12,
Wherein the width of the diffusely reflective coating film is equal to or smaller than the width of the first finger electrode. The method according to any one of claims 11 to 13,
The second electrode portion may include a plurality of second finger electrodes extending in the first direction and a plurality of second finger electrodes extending in a second direction intersecting with the first direction, And a second bus bar electrode connected to the second bus bar electrode. The method of claim 14,
Wherein the second bus bar electrode is bonded to an interconnector, and the diffusely reflective coating film is formed on the entire lower surface of the second finger electrodes. 16. The method of claim 15,
Wherein the width of the diffusely reflective coating film is equal to or smaller than the width of the second finger electrode. The method according to any one of claims 11 to 13,
The second electrode portion includes a plurality of second bus bar electrodes extending in a second direction intersecting the first direction and a plurality of second bus bar electrodes formed on a sheet on the rear surface of the substrate except the portion where the second bus bar electrodes are formed, A solar cell comprising two electrodes.

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