Device for generating photovoltaic power and method for manufacturing same

Disclosed are a solar cell apparatus and a method of fabricating the same. The solar cell apparatus includes a substrate; a first cell on the substrate; a second cell adjacent to the first cell; a first insulating film covering the first and second cells; and a connection member connecting the first cell with the second cell. The first insulating film includes a first via hole for exposing the first cell and a second via hole for exposing the second cell, and the connection member connects the first cell with the second cell through the first and second via holes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national stage application of International Patent Application No. PCT/KR2011/003124, filed Apr. 27, 2011, which claims priority to Korean Application No. 10-2010-0074417, filed Jul. 30, 2010, the disclosures of each of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The embodiment relates to a solar cell apparatus and a method of fabricating the same.

BACKGROUND ART

Recently, as energy consumption is increased, a solar cell apparatus has been developed to convert solar energy into electric energy.

In particular, a CIGS-based solar cell apparatus, which is a PN hetero junction apparatus having a substrate structure including a glass substrate, a metallic back electrode layer, a P type CIGS-based light absorbing layer, a high-resistance buffer, and an N type window layer, has been extensively used.

In addition, studies and research have been performed to improve electric characteristics of the solar cell apparatus, such as the low resistance and high transmittance rate. Further, studies and research have been pursued to develop a flexible solar cell apparatus.

DISCLOSURE

Technical Problem

The embodiment provides a solar cell apparatus, which can be readily fabricated and has high reliability by preventing the disconnection, and a method of fabricating the same.

Technical Solution

A solar cell apparatus according to the embodiment includes a substrate; a first cell on the substrate; a second cell adjacent to the first cell; a first insulating film covering the first and second cells; and a connection member connecting the first cell with the second cell, wherein the first insulating film includes a first via hole for exposing the first cell and a second via hole for exposing the second cell, and the connection member connects the first cell with the second cell through the first and second via holes.

A solar cell apparatus according to the embodiment includes a substrate; a first cell on the substrate; a second cell adjacent to the first cell; a connection member connected to the first and second cells; and a plating layer coated on an outer surface of the connection member.

A method of fabricating a solar cell apparatus according to the embodiment includes the steps of forming first and second cells adjacent to each other on the substrate; forming a first insulating film having a first via hole for exposing the first cell and a second via hole for exposing the second cell; and forming a connection member connected to the first and second cells through the first and second via holes.

Advantageous Effects

According to the solar cell apparatus of the embodiment, adjacent cells are connected with each other by the connection member connected to the cells through the via hole formed in the insulating film. After the insulating film is disposed on the cells and via holes are formed in the insulating film to expose the cells, the connection member is printed corresponding to the via holes.

That is, since the connection member is formed through the printing scheme, the solar cell apparatus according to the embodiment can be readily fabricated.

In addition, in a state that the connection member has been printed, the connection member and the cells are subject to the electroplating process. Thus, the connection member can be securely connected to the cells and the solar cell apparatus according to the embodiment can prevent the disconnection.

Further, the connection strength between the connection member and the cells can be reinforced due to the plating layer and the solar cell apparatus according to the embodiment may have the improved electric characteristics.

Therefore, the solar cell apparatus according to the embodiment can be readily fabricated and may have the improved reliability.

BEST MODE

In the description of the embodiments, it will be understood that when a substrate, a layer, a film or an electrode is referred to as being “on” or “under” another substrate, another layer, another film or another electrode, it can be “directly” or “indirectly” on the other substrate, the other layer, the other film, or the other electrode, or one or more intervening layers may also be present. Such a position of the layer has been described with reference to the drawings. The size of the elements shown in the drawings may be exaggerated for the purpose of explanation and may not utterly reflect the actual size.

FIG. 1is a plan view showing a solar cell panel according to the embodiment,FIG. 2is an enlarged plan view showing a connection state between first and second cells C1and C2, andFIG. 3is a sectional view taken along line A-A′ ofFIG. 1.

Referring toFIGS. 1 to 3, the solar cell panel according to the embodiment includes a support substrate100, a plurality of cells C1, C2. . . and Cn, a first insulating film310, a second insulating film320, a plurality of connection members400, a plating layer500, a first bus bar610and a second bus bar620.

The support substrate10supports the cells C1, C2. . . and Cn, the first insulating film310, the second insulating film320, and the connection members400. The support substrate100has a plate shape and is flexible.

The support substrate100may be an insulator. For instance, the support substrate100may be a stainless steel substrate or a polymer substrate including ethylenevinylacetate (EVA) or polyimide (PI).

The cells C1, C2. . . and Cn are disposed on the support substrate100. The cells C1, C2. . . and Cn are spaced apart from each other in the form of a matrix. In addition, the cells C1, C2. . . and Cn may extend in one direction and can be arranged in the form of a stripe.

The cells C1, C2. . . and Cn are connected with each other in series or parallel. In detail, the cells C1, C2. . . and Cn spaced apart from each other are connected with each other in series or parallel by the connection members400, the first bus bar610and the second bus bar620.

The cells C1, C2. . . and Cn receive solar light to convert the solar light into electric energy. For instance, the cells C1, C2. . . and Cn may include silicon solar cells, semiconductor compound solar cells, such as CIGS solar cells, or dye-sensitized solar cells.

Each of the cells C1, C2. . . and Cn may include a back electrode210, a light absorbing part220, a buffer230, a high-resistance buffer240, and a window250.

The back electrode210is provided on the support substrate100. The back electrode210is a conductive layer. For instance, the back electrode210may include molybdenum (Mo).

The back electrode210has a relatively large area. That is, the back electrode210has an area larger than an area of the light absorbing part220, the buffer230, the high-resistance buffer240and the window250.

Therefore, the top surface of the back electrode210is partially exposed. In detail, a part of the back electrode210laterally protrudes with respect to the lateral side of the light absorbing part220.

The light absorbing part220is disposed on the back electrode210. The light absorbing part220absorbs solar light incident through the window250. For instance, the light absorbing part220may include group I-III-VI compounds. For instance, the light absorbing part220may include the Cu(In,Ga)Se2(CIGS) crystal structure, the Cu(In)Se2crystal structure, or the Cu(Ga)Se2crystal structure.

The light absorbing part220has an energy bandgap in the range of about 1 eV to about 1.8 eV.

The buffer230is disposed on the light absorbing part220. The buffer230may include CdS and have an energy bandgap in the range of about 2.2 eV to 2.4 eV.

The high-resistance buffer240is disposed on the buffer230. The high-resistance buffer240may include i-ZnO, which is not doped with impurities. The high-resistance buffer240may have an energy bandgap in the range of about 3.1 eV to about 3.3 eV.

The window250is formed on the high-resistance buffer240. The window250is a transparent conductive layer. In addition, the window250has resistance higher than that of the back electrode210. For instance, the resistance of the window250is ten times to two hundred time higher than the resistance of the back electrode210.

The window250may include Al-doped zinc oxide (AZO) or Ga-doped zinc oxide (GZO). The window250may have a thickness in the range of about 800 nm to about 1200 nm.

The light absorbing part220, the buffer230, the high-resistance buffer240and the window250may have the substantially same area. At this time, the area of the light absorbing part220, the buffer230, the high-resistance buffer240and the window250may be smaller than the area of the back electrode210.

Thus, the light absorbing part220may be laminated on the back electrode210in the form of a stair. That is, a step difference is formed between the light absorbing part220and the back electrode210. The buffer230, the high-resistance buffer240and the window250may not form the step difference with respect to the back electrode210. That is, outer peripheral portions of the light absorbing part220, the buffer230, the high-resistance buffer240and the window250match with each other.

An opening area OA exposed through the light absorbing part220is formed in the back electrode210. That is, the opening area OA is a region on the top surface of the back electrode210where the light absorbing part220is not disposed.

The first insulating film310is disposed on the support substrate100. The first insulating film310covers the cells C1, C2. . . and Cn. In detail, the first insulating film310is disposed on the cells C1, C2. . . and Cn. The first insulating film310may cover the entire surface of the cells C1, C2. . . and Cn. In addition, the first insulating film310may closely adhere to the cells C1, C2. . . and Cn and the support substrate100

The first insulating film310is a transparent insulator. The first insulating film310may include ethylenevinylacetate.

A plurality of first via holes311and second via holes312are formed in the first insulating film310.

The first via holes311are formed through the first insulating film310and expose a part of the cells C1, C2. . . and Cn. In detail, the first via holes311expose the top surface of the windows250of the cells C1, C2. . . and Cn. The first via holes311are located corresponding to outer peripheral portions of the windows250of the cells C1, C2. . . and Cn.

The second via holes312are formed through the first insulating film310and expose a remaining part of the cells C1, C2. . . and Cn. In detail, the second via holes312expose the top surface of the back electrode210of the cells C1, C2. . . and Cn. In more detail, the second via holes312are located corresponding to the opening area OA.

The second insulating film320is disposed on the first insulating film310. The second insulating film320may cover the connection members400, the first bus bar610and the second bus bar620. The second insulating film320may cover an entire top surface of the first insulating film310.

In addition, the second insulating film320may adhere to the first insulating film310. The second insulating film320can seal the cells C1, C2. . . and Cn, the connection members400, the first bus bar610and the second bus bar620against the outside.

The second insulating film320is a transparent insulator. In addition, the second insulating film320is flexible and has high durability. In addition, the second insulating film320may be formed by using a material the same as that of the first insulating material. The second insulating film320may include ethylenevinylacetate, polyimide or polyethyleneterephthalate.

The connection members400are disposed among the cells C1, C2. . . and Cn, respectively. In addition, the connection members400are disposed inside the first and second via holes311and312on the first insulating substrate.

The connection members400connect the cells C1, C2. . . and Cn with each other. In detail, the connection members400connect the adjacent cells C1, C2. . . and Cn with each other. That is, the connection members400connect the adjacent cells C1, C2. . . and Cn with each other through the first and second via holes311and312. In other words, the connection members400are connected to the cells C1, C2. . . and Cn through the first and second via holes311and312.

The connection members400connect the cells C1, C2. . . and Cn with each other in series. That is, the connection members400connect the window250of one cell to the back electrode210of the adjacent cell. The connection members400cover the first and second via holes311and312. That is, one connection member400may simultaneously cover one first via hole311and one second via hole312.

The connection members400are conductors. For instance, the connection members400may include conductive pastes or conductive tapes. In detail, the connection members400may include Ag pastes or copper plates.

The connection members400are flexible. That is, the connection members400may be curved as the support substrate100is bent.

The connection members400are connected to the cells C1, C2. . . and Cn through the first and second via holes311and312. That is, some connection members400are disposed inside the first and second via holes311and312and connected to the cells C1, C2. . . and Cn.

For instance, as shown inFIGS. 1 to 3, one of the connection members400connects the first and second cells C1and C2with each other in series. The first and second cells C1and C2are disposed adjacent to each other. One of the first via holes311exposes a part of the window250of the first cell C1and one of the second via holes312exposes a part of the top surface of the back electrode211of the second cell C2.

The connection member400is connected to the window250of the first cell C1through the first via hole311. At this time, the connection member400directly makes contact with the window250of the first cell C1.

In addition, the connection member400is connected to the open area OA of the back electrode210of the second cell C2through the second via hole312. At this time, the connection member400directly makes contact with the back electrode210of the second cell C2.

The plating layer500surrounds the connection members400. In addition, the plating layer500is disposed on the windows250of the cells C1, C2. . . and Cn exposed through the first via holes311. The plating layer500is disposed on the top surface of the back electrode21of the cells C1, C2. . . and Cn exposed through the second via holes312. The plating layer500may be disposed between the connection members400and the window250of the cells C1, C2. . . and Cn. In addition, the plating layer500may be disposed between the connection members400and the back electrode210of the cells C1, C2. . . and Cn.

The connection members400can be connected to the window250and the back electrode210of the cells C1, C2. . . and Cn through the plating layer500. In detail, the plating layer500is disposed between the connection members400and the window250of the cells C1, C2. . . and Cn to improve the electric and mechanical connection property between the connection members400and the window250of the cells C1, C2. . . and Cn. In the same manner, the plating layer500is disposed between the connection members400and the back electrode210of the cells C1, C2. . . and Cn to improve the electric and mechanical connection property between the connection members400and the back electrode210of the cells C1, C2. . . and Cn.

That is, the plating layer500is plated on the connection members400, the window250of the cells C1, C2. . . and Cn and the back electrode210of the cells C1, C2. . . and Cn.

The plating layer500is a conductive layer and may include a metal having low resistance. The plating layer may include Cu, Ag or Au.

The first bus bar610connects the cells C1, C2. . . and Cn with each other in parallel. In detail, the first bus bar610is connected to the back electrode210of the cells C1, C2. . . and Cn disposed at the outer peripheral portion. The first bus bar610is disposed between the first insulating film310and the back electrode210of the cells C1, C2. . . and Cn. The first bus bar610may extend in one direction and is connected to the adjacent solar cell panel or the external electricity storage device.

The second bus bar620connects the cells C1, C2. . . and Cn with each other in parallel. In detail, the second bus bar620is connected to the window250of the cells C1, C2. . . and Cn disposed at the other outer peripheral portion. The second bus bar620is disposed between the first insulating film310and the window250of the cells C1, C2. . . and Cn. The second bus bar620may extend in one direction and is connected to the adjacent solar cell panel or the external electricity storage device.

The first and second bus bars610and620are conductors and can be formed by using Cu or Ag. The first and second bus bars610and620may be prepared in the form of the paste or the conductive tape.

The connection members400connect adjacent cells C1, C2. . . and Cn with each other through the first and second via holes311and312. In particular, the connection members400are connected to the top surface of the window250and the top surface of the back electrode210of the cells C1, C2. . . and Cn. The connection members400can be formed by printing paste.

That is, since the connection members400are formed through the printing scheme, the solar cell apparatus according to the embodiment can be readily fabricated through the automation process.

In addition, after the connection members400have been printed, the plating layer500can be formed on the connection members400and the cells C1, C2. . . and Cn through the electroplating process. Thus, the connection members400can be securely connected to the cells C1, C2. . . and Cn and the solar cell panel according to the embodiment can prevent the disconnection.

In addition, the connection strength between the connection members400and the cells C1, C2. . . and Cn can be improved due to the plating layer, so the solar cell panel according to the embodiment may have the improved electric and mechanical characteristics.

Thus, the solar cell panel according to the embodiment can be readily fabricated and can improve the reliability.

FIGS. 4 to 9are sectional views showing the method of fabricating the solar cell panel according to the embodiment. The above description about the solar cell panel will be basically incorporated in the description about the method of fabricating the solar cell.

Referring toFIG. 4, a plurality of back electrodes210are formed on the support substrate100.

In order to form the back electrodes210, a back electrode layer is formed on the support substrate100. The back electrode layer can be formed by depositing Mo on the support substrate100through the vacuum deposition process, such as the sputtering process.

Then, the back electrode layer is patterned by a laser, so that the back electrode layer is divided into the back electrodes210.

Referring toFIG. 5, a light absorbing layer221, a buffer layer231, a high-resistance buffer layer241and a window layer252are formed on the back electrodes.

The light absorbing layer221can be formed through the sputtering scheme or the evaporation scheme.

For instance, the light absorbing layer221may be formed through various schemes such as a scheme of forming a Cu(In,Ga)Se2(CIGS) based light absorbing layer221by simultaneously or separately evaporating Cu, In, Ga, and Se and a scheme of performing a selenization process after a metallic precursor layer has been formed

Regarding the details of the selenization process after the formation of the metallic precursor layer, the metallic precursor layer is formed on the back electrodes210through a sputtering process employing a Cu target, an In target, or a Ga target.

Thereafter, the metallic precursor layer is subject to the selenization process so that the Cu (In, Ga) See(CIGS) based light absorbing layer221is formed.

In addition, the sputtering process employing the Cu target, the In target, and the Ga target and the selenization process may be simultaneously performed.

Further, a CIS or a CIG based light absorbing layer may be formed through the sputtering process employing only Cu and In targets or only Cu and Ga targets and the selenization process.

Then, CdS is deposited through the sputtering process or the chemical bath deposition (CBD) process to form the buffer layer231.

After that, ZnO is deposited on the buffer layer231through the sputtering process to form the high-resistance buffer layer241.

The buffer layer231and the high-resistance buffer layer241may have the shallow thickness. For instance, the buffer layer231and the high-resistance buffer layer241may have the thickness in the range of about 1 nm to about 80 nm.

Then, a transparent conductive material is deposited on the high-resistance buffer layer241to form the window layer252. For instance, the window layer252can be formed by depositing Al-doped zinc oxide (AZO) on the high-resistance buffer layer241through the sputtering process.

Referring toFIG. 6, the light absorbing layer221, the buffer layer231, the high-resistance buffer layer241, and the window layer252are patterned through the laser or the mechanical scribing. In detail, the light absorbing layer221, the buffer layer231, the high-resistance buffer layer241, and the window layer252are simultaneously patterned. As a result, a plurality of light absorbing parts220, a plurality of buffers230, a plurality of high-resistance buffers240and a plurality of windows250are formed.

Thus, a plurality of cells C1, C2. . . and Cn including the back electrode210, the light absorbing part220, the buffer230, the high-resistance buffer240and the window250are formed on the support substrate100.

The light absorbing layer221, the buffer layer231, the high-resistance buffer layer241, and the window layer252are patterned such that the top surface of the back electrode layers210can be partially exposed. Thus, the open area is formed in the top surface of the back electrodes210.

Therefore, the back electrodes210and the light absorbing parts220are laminated in the shape of a stair.

Referring toFIG. 7, the first insulating film310is formed on the cells C1, C2. . . and Cn. That is, the first insulating film310is combined onto the support substrate100having the cells C1, C2. . . and Cn. After that, a plurality of first via holes311and second via holes311and312are formed in the first insulating film310.

The first via holes311expose the top surfaces of the windows250and the second via holes312expose the open areas OA of the back electrodes210.

Referring toFIG. 8, a plurality of connection members400are formed on the first insulating film310. The connection members400are formed through the printing scheme, such as the silk screen printing.

That is, conductive paste including conductive particles, such as metal particles, can be printed among the cells C1, C2. . . and Cn. In addition, the conductive paste may be printed such that the first and second via holes311and312can be covered with the conductive paste. Thus, the connection members400can be formed.

After that, the connection members400can be subject to the drying process or the heat treatment process.

Referring toFIG. 9, the plating layer500is formed and then the second insulating film320is formed on the first insulating film310.

The plating layer500can be formed through the electroplating process. For instance, a negative electrode is connected to the connection member400so that metallic ions, such as copper ions included in an electrolyte, can be plated on the connection members400, the exposed windows250and the exposed back electrodes210.

The connection members400may not completely adhere to the back electrodes210and the windows250. That is, some connection members400may directly make contact with the back electrodes210and the windows250, but remaining connection members400may be spaced apart from the back electrodes210and the windows250while forming a predetermined space therebetween.

At this time, the plating layer500is formed on the connection members400, the top surfaces of the back electrodes210and the top surfaces of the windows250through the electroplating process. In addition, the plating layer500is formed in the predetermined space between the connection members400and the back electrode layers210and between the connection members400and the windows250.

That is, the metallic ions contained in the electrolyte can be plated in the predetermined space between the connection members400and the windows250and between the connection members400and the back electrode layers210.

Thus, the plating layer500may improve the electric and mechanical characteristics between the connection members400and the windows250and between the connection members400and the back electrode layers210.

As described above, according to the solar cell panel of the embodiment, the connection members400can be formed at a time through the printing scheme. In addition, the solar cell panel according to the embodiment may have the improved characteristics due to the plating layer500.

INDUSTRIAL APPLICABILITY

The solar cell apparatus and the method of fabricating the same according to the embodiment can be applied in the field of solar light generation.