JP2002094102A - Interconnector for both sides junction type solar cell, solar cell using it and its connecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an interconnector ensuring highly reliable and stable series connection of both sides junction type solar cells simply. SOLUTION: The interconnector 2 used between two both sides junction type solar cells 1 is formed of a planar conductive material and has a plurality of parts split by one or more slits 3a at least one end thereof. At least one split end has a connection part 3 being connected with an electrode 7 provided on the light receiving face of one cell 1 and at least another split end has a part 3 being connected with an electrode 7 provided on the backside of one cell 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interconnector used for electrical interconnection between semiconductor photovoltaic cells, and more particularly, to a double-sided junction type photovoltaic cell having a pn junction on both a light receiving surface side and a back side. The present invention relates to an interconnector for connection between them.

[0002]

2. Description of the Related Art FIG. 9A is a schematic sectional view showing the most common solar cell. In each drawing of the present application, dimensional relationships such as length and thickness are appropriately changed for clarification and simplification of the drawings, and do not represent actual dimensional relationships. Further, the same reference numerals in each drawing indicate the same or corresponding parts.

[0003] The solar cell 1 of FIG. 9A includes a semiconductor substrate 1a. In general, a p-type silicon substrate is often used as the semiconductor substrate 1a. p-type substrate 1
An n-type (n ⁺ ) layer 5 having a high impurity concentration is formed on the light receiving surface side of a. A comb-shaped current collecting electrode (not shown) is formed on the n-type layer 5, and the back surface of the substrate 1a is covered with a back electrode (not shown). Note that FIG.
In a solar cell as shown in FIG.
It is needless to say that a p-type (p ⁺ ) layer having a high impurity concentration may be formed on the back surface side of the substrate, and a solar cell having a structure in which p-type and n-type are inverted is also possible.

Since a single solar cell has a low output voltage, it is generally used as a solar cell module in which a plurality of cells are connected in series. In the solar battery cell as shown in FIG. 9A, the entire light receiving surface and the entire back surface have a single polarity and opposite polarities. Therefore, between such two solar cells, one end of one interconnect is inevitably connected to the external connection electrode on the light receiving surface of one cell, and the other end is connected to the other cell. Connected to back electrode.

[0005]

FIG. 9B shows, for example, the 2nd World Conference on Photovoltaic Solar Energ
One example of a double-sided junction solar cell as disclosed in Y Conversion, 1998, pp. 3511-3514 is shown in a schematic cross-sectional view. In the cell of FIG. 9 (B), a single n ⁺ layer 5 is formed on the light receiving surface side of p-type substrate 1a in the same manner as in FIG. 9 (A). In addition to the p ⁺ region 6 formed in a tooth shape, an n ⁺ layer 5 also formed in a comb tooth shape is formed. That is,
In the double-sided junction solar cell, a pn junction is formed not only on the light receiving surface side of the substrate 1a but also on the back surface side. Then, on the back surface of the cell as shown in FIG. 9B, a comb-shaped current collecting electrode (not shown) corresponding to the n ⁺ region 5 is formed, and the p ⁺ region 6 is formed. , And a comb-like collecting electrode (not shown) corresponding to.

[0006] In a double-sided junction solar cell, it is possible to efficiently extract even carriers generated near the back surface as output power. Therefore, a double-sided junction type solar cell is preferable as a solar cell for outer space in which light can enter from the back side, and is also preferable in that the characteristic deterioration due to radiation exposure in outer space is small.

[0007] The structure of the double-sided junction solar cell is not limited to that shown in FIG.
A cell having a structure in which the light receiving surface side and the rear surface side of FIG. 9B are inverted is possible, and as shown in FIG. 9C, the n ⁺ region is provided on both the light receiving surface side and the rear surface side of the substrate 1a. 5 and p ⁺ region 6 may both be formed. Needless to say, a double-sided junction solar cell having a structure in which the p-type and the n-type are inverted from each other is also possible.

When a plurality of double-sided junction solar cells are connected in series as described above, it cannot be performed simply as in the case of ordinary series connection of solar cells as described above. For example, when two of the cells in FIG. 9B are connected in series, not only the n-type external connection electrode on the light receiving surface side of one of the cells but also the n ⁺ region external connection electrode on the back surface of the other cell are used. Must be connected to the p ⁺ region external connection electrode on the back side of the cell. Therefore, the two-sided junction type solar cell is connected in series by connecting one end to one electrode of one cell and the other end to one electrode of the other cell as in a normal solar cell. This cannot be done with a single interconnector connected to

Therefore, when two of the double-sided junction type solar cells shown in FIG. 9 (B) are connected in series, usually, two conventional interconnectors are used as shown in FIG. FIG. 10 is a plan view of the solar cell viewed from the light receiving surface side, in which two double-sided junction solar cells 1 are connected in series by two interconnectors. (In the case of a solar cell with a light-receiving surface and a double-sided junction type cell, a comb-shaped current collecting electrode is also formed on the back surface, but the description on a plan view is omitted because it is complicated.
Hereinafter, the same applies to all plan views. 10, the connection 3 at the lower end of the left interconnector is connected to the electrode for the n ⁺ region on the light receiving surface side of the lower cell 1, and the connection 4 at the upper end is the back surface of the upper cell 1. Side p
⁺ Connected to the area electrode. On the other hand, the connection part 3 at the lower end of the right interconnector 2 is connected to the n ⁺ region electrode on the back side of the lower cell 1, and the connection part 4 at the upper end thereof is p ⁺ on the back side of the upper cell 1. It is connected to the region electrode.

[0010] The use of two conventional interconnectors to form one series connection between two double-sided junction solar cells as described above requires the use of an interconnector required to form a solar cell module. The number of parts is increased, and the connection process is complicated. Also,
When two interconnectors are used for one series connection, a stress is generated due to the contact or crossing of the connectors due to a positional shift between the connectors, and the connector is caused by the stress. The connection may peel off from the solar cell. Conversely, if the mutual gap between the interconnectors is too wide due to the positional shift between the interconnectors, the position of the connecting portion of the connector may deviate from the external connection electrode region of the solar cell.

In view of the situation in the prior art, it is a main object of the present invention to provide an interconnector capable of simplifying a stable and reliable series connection between double-sided junction solar cells.

[0012]

According to the present invention, an interconnector used between two double-sided junction solar cells is formed of a plate-like conductive material, and at least one end of the plate-like material is provided. The portion has a plurality of divided ends divided by one or more slits, and at least one of the divided ends has a connection portion for connecting to an electrode provided on a light receiving surface of one of the cells, At least one other of the divided ends has a connection portion for connecting to an electrode provided on the back surface of one of the cells.

The other end of the plate-shaped material has a connecting portion for connecting to an electrode provided on either the light receiving surface or the back surface of the other cell.

The other end of the plate material may also have a plurality of divided ends divided by at least one or more slits, and at least one of the divided ends at the other end is the other end of the cell. It has a connection portion for connecting to an electrode provided on the light receiving surface, and at least one other of the other divided ends has a connection portion for connecting to an electrode provided on the back surface of the other cell. Can have.

It is preferable that a slit for relaxing stress is provided in an intermediate region between one end and the other end of the plate-like material constituting the interconnector.

[0016] A bent portion for relaxing stress may be provided in an intermediate region between one end and the other end of the plate-like material constituting the interconnector.

Among the divided ends of the interconnector, the total width of at least one connecting portion for connecting to the electrode provided on the light receiving surface of the cell is equal to the total width of the connecting portion for connecting to the electrode provided on the back surface of the cell. Preferably, the width is wider than the total width of the one or more connection portions.

It is preferable that part or all of the interconnector other than the connection part is covered with an insulating material.

[0019]

FIG. 1 schematically illustrates a first embodiment of the present invention. FIG. 1A is a plan view of the photovoltaic cell viewed from the light receiving surface side, and FIG. 1B is an enlarged side view corresponding to FIG. 1A.

Referring to FIG. 1, there is shown in FIG.
Between the two double-sided junction solar cells 1
-Connector 2 is connected. In other words, these
Each of the devices 1 has n on the light-receiving surface side of its p-type substrate⁺Layer 5
With n on the back side⁺Layer 5 and p ⁺It has a layer 6. Inn
The connector 3 has a slit 3a at one end thereof.
ing. Two parts divided by this slit 3a
One of the connection portions 3 at the split end is provided on the light receiving surface of the cell 1.
N via the external connection electrode 7⁺Electrically to layer 5
Connected, and the other connecting portion 3 is provided on the back surface of the cell 1.
N via the external connection electrode 7⁺Connected to layer area 5
I have. Then, at the other end of the interconnector 2
The connecting portion 4 is provided on the back surface of another cell 1.
P through the connection electrode 8⁺Electrically connected to the layer region 6
Have been.

By using one interconnector as shown in FIG. 1, one series connection between two double-sided junction solar cells is formed as shown in FIG.
It is no longer necessary to use two conventional interconnectors as shown in (1), and the connection process becomes simple and reliable. In addition, the use of the interconnector of FIG. 1 eliminates the problem of stress generation due to contact or intersection between the two interconnectors, and prevents the connection portion of the interconnector from deviating from the external connection electrode due to displacement. Prevention is also easy.

FIG. 2, similar to FIG. 1A, illustrates a second embodiment of the present invention in a schematic plan view. The interconnector 2 of the second embodiment has two ends at one end.
This is different from the first embodiment in that two slits 3a are provided. That is, the connection portion 3 of the divided end portion sandwiched between the two slits 3a is connected to the light receiving surface side of the solar cell 1, and the two connection portions of the two divided end portions formed on both outer sides of the two slits 3a. The unit 3 is connected to the back side of the cell 1.

If the interconnector of the second embodiment is used, stress is generated in the connecting portion due to, for example, a thermal cycle in a space environment, and a connection failure occurs in one connecting portion 3 on both outer sides of the two slits 3a. Even if it happens,
If the other connection part 3 is normal, the connection failure does not occur as a whole, and the reliability of the problem of the occurrence of the connection failure can be improved.

FIG. 3 schematically illustrates a third embodiment of the present invention. FIG. 3A shows a plan view as viewed from the light receiving surface side of the solar cell, and FIG. 3B shows an enlarged side view corresponding to FIG. 3A. The third embodiment is similar to the first embodiment, and differs only in that the structures on the light receiving surface side and the back surface side of the solar battery cell 1 are inverted. That is, each of the solar cells 1 in FIG. 3 has n on the light receiving surface side of its p-type substrate 1a.
^{It has a +} layer region 5 and a p ⁺ layer region 6, and has an n ⁺ layer 5 on the back surface side.

It will be apparent that the use of the interconnector in the third embodiment can provide the same effects as in the first embodiment.

FIG. 4 schematically illustrates a fourth embodiment of the present invention. FIG. 4A is a plan view as viewed from the light receiving surface side of the solar cell, and FIG. 4B is an enlarged partial side view corresponding to FIG. 4A.

In the fourth embodiment, FIG.
The double-sided junction solar cell as shown in FIG. That is, each of the cells 1 in FIG.
On both the light receiving surface side and the back surface side of the mold substrate 1a, n
⁺ Layer region 5 and p ⁺ layer region 6. In the interconnector 2, a slit 3a is provided at one end and a slit 4a is provided at the other end.
a is provided. One of the connecting portions 3 at the two divided ends divided by the slit 3a at one end is electrically connected to the n ⁺ layer region 5 via the external connection electrode 7 provided on the light receiving surface of the cell 1. The other connection portion 3 is connected to the n ⁺ layer region 5 via an external connection electrode 7 provided on the back surface side of the cell 1. Similarly, one of the connection portions 3 at the two divided ends divided by the slit 4a at the other end of the interconnector 2 is connected via an external connection electrode 8 provided on the light receiving surface of another cell 1. Te is connected to the p ⁺ layer region 6, the other connection portion 3 is connected via the external connection electrodes 8 provided on the back surface of the cell 1 to the p ⁺ layer region 6.

As described above, by using the interconnector having not only the slit 3a at one end but also the slit 4a at the other end, the n ⁺ layer region 5 and the p ⁺ It is possible to connect the solar cells having the ⁺ layer region 6 in series with one interconnector.

FIG. 5, similar to FIG. 1A, illustrates a fifth embodiment of the present invention in a schematic plan view. The interconnector of the fifth embodiment is different from that of the first embodiment only in that the interconnector of the fifth embodiment has a stress relaxation slit 9a cut from both sides toward the center in an intermediate region between both ends. Is different. Such a stress relaxing slit can be formed simultaneously when an interconnector shape having a slit 3a at one end is formed from a plate-like material by, for example, photoetching.

By providing such a stress relaxing slit 9a, even if the distance between the solar cells connected in series expands and contracts due to thermal causes, the voltage is applied to the connection between the interconnector and the solar cells. The stress applied to the interconnector is reduced, and the connection reliability of the interconnector can be improved.

Incidentally, such a slit 9a for stress relaxation is used.
It can be seen that the invention can be preferably applied not only to the interconnector in the first embodiment shown in FIG. 1 but also to the interconnector in the second to fourth embodiments shown in FIGS. .

FIG. 6 illustrates a sixth embodiment of the present invention in a schematic plan view, similar to FIG. The interconnector of the sixth embodiment differs from that of the first embodiment only in that a stress relief bending portion 9b formed by bending is provided in an intermediate region between both ends. By providing such a stress relaxation bending portion 9b, even if the distance between the solar cells connected in series expands and contracts due to thermal causes, the expansion and contraction of the stress relaxation bending portion 9b due to elastic bending deformation. Is absorbed, the stress applied to the connection portion between the interconnector and the solar cell is reduced, and the connection reliability of the interconnector can be improved. It should be noted that the stress relaxation bending portion 9b can be preferably introduced not only into the first embodiment shown in FIG. 1 but also into the interconnectors in the second to fourth embodiments shown in FIGS. Needless to say.

FIG. 7 schematically illustrates a seventh embodiment of the present invention, similar to FIG. In the seventh embodiment, connection portions 3 at both ends of the interconnector 2 are provided.
The fourth embodiment differs from the first embodiment only in that the insulating film 10 is provided in at least a part of the region except for the region 4. By providing such an insulating film 10, short circuit failure due to contact between the interconnector 2 and the substrate 1a of the solar cell can be prevented, and the reliability of the interconnector can be improved. Needless to say, such an insulating film 10 can be applied not only to the first embodiment but also to the interconnector of any other embodiment.

FIG. 8 schematically illustrates an eighth embodiment of the present invention, similar to FIG. In the eighth embodiment, the cover glass 12 is bonded to the light receiving surface of the solar cell 1 by the silicone resin 11.
The silicone resin 11 used for bonding the cover glass 12 extends so as to insulate at least a part of the surface region of the interconnector.
It will be apparent that the same effect as in the seventh embodiment can be obtained by the silicon resin 11 extended in the surface region of the interconnector as described above. Further, according to the present embodiment, the insulating layer is formed on the surface of the interconnector without forming an insulating layer on the surface area of the interconnector in advance and without requiring an additional step in the manufacturing process of the solar cell module. can do.

By the way, in a solar battery cell, power is normally generated by collecting an excess minority carrier generated by absorption of light incident from a light receiving surface by a pn junction electric field, and power is generated by light absorbed near the light receiving surface. The current component is larger than the current component due to light absorbed near the back surface. Therefore, by making the total width of each connection portion at both ends of the interconnector a width corresponding to the current component at each connection portion, it is possible to improve performance by reducing the area occupied by the connection portion in the solar battery cell. it can. For this purpose, when regions of the same conductivity type exist on the light receiving surface side and the back surface side, it is preferable that the total width of the connection region on the back surface side is smaller than the total width of the connection region on the light receiving surface side.

[0036]

As described above, according to the present invention, it is possible to provide an interconnector capable of easily performing a stable and highly reliable series connection between double-sided junction solar cells.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a first embodiment of the present invention.

FIG. 2 is a diagram schematically showing a second embodiment of the present invention.

FIG. 3 is a diagram schematically showing a third embodiment of the present invention.

FIG. 4 is a diagram schematically showing a fourth embodiment of the present invention.

FIG. 5 is a diagram schematically showing a fifth embodiment of the present invention.

FIG. 6 is a diagram schematically showing a sixth embodiment of the present invention.

FIG. 7 is a view schematically showing a seventh embodiment of the present invention.

FIG. 8 is a diagram schematically showing an eighth embodiment of the present invention.

FIG. 9 is a schematic sectional view showing a layer structure of a solar battery cell.

FIG. 10 is a schematic plan view showing a series connection method using a conventional interconnector between two double-sided junction solar cells.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 solar cell, 1 a p-type semiconductor substrate, 2 interconnector, 3, 4 connection portion, 5 n ⁺ region, 6 p ⁺ region, external connection electrode for 7 n ⁺ region, external connection electrode for 8 p ⁺ region, 9 a Slit for stress relaxation, 9b Bent portion for stress relaxation, 10 insulating film, 11 silicone resin, 12
cover glass.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsu Yuji 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Minoru Kaneiwa 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Hidetoshi Washio 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Prefecture Inside Sharp Corporation (72) Inventor Sumio Matsuda 2-4-1 Hamamatsucho, Minato-ku, Tokyo Space development business In-house (72) Inventor Kazuhiro Aoyama 2-4-1 Hamamatsucho, Minato-ku, Tokyo Space Development Business Inside (72) Inventor Osamu Yasuzawa 2-4-1 Hamamatsucho, Minato-ku, Tokyo Space Development Business Group F term (reference) 5F051 AA02 BA17 DA03 DA20 EA02 EA17 FA30 GA04 JA20

Claims (12)

[Claims] 1. An interconnector used between two double-sided junction solar cells, wherein the interconnector is formed of a plate-shaped conductive material, and at least one end of the plate-shaped material is 1 It has a plurality of divided ends divided by the above slit, and at least one of the divided ends has a connection portion for connecting to an electrode provided on a light receiving surface of one of the cells, and An interconnector characterized in that at least one other end has a connection portion for connecting to an electrode provided on the back surface of the one cell. 2. The other end of the plate-like material has a connection portion for connecting to an electrode provided on either the light receiving surface or the back surface of the other cell.
An interconnector as described in. 3. The other end of the plate-like material also has at least one end.
It has a plurality of divided ends divided by the above slit, and at least one of the divided ends of the other end is a connecting portion for connecting to an electrode provided on a light receiving surface of the other cell. 2. The interface according to claim 1, wherein at least one of the divided ends of the other end has a connection portion for connecting to an electrode provided on a back surface of the other cell. 3. connector. 4. The plate-shaped material according to claim 1, wherein a slit for relaxing stress is provided in an intermediate region between the one end and the other end. The interconnector according to claim. 5. The plate-like material according to claim 1, wherein a bent portion for relaxing stress is provided in an intermediate region between the one end and the other end. The interconnector according to claim 1. 6. A total width of one or more of the connecting portions for connecting to an electrode provided on the light receiving surface among the divided end portions is one for connecting to an electrode provided on the back surface.
The interconnector according to any one of claims 1 to 5, wherein the interconnector is wider than the total width of the connection portions. 7. The semiconductor device according to claim 1, wherein a part or all of the region other than the connection portion is covered with an insulating material.
The interconnector according to any one of claims 1 to 6. 8. A semiconductor substrate of a first conductivity type having a second conductivity type layer on the light receiving surface side and a first conductivity type layer region on the back surface side.
A double-sided junction type solar cell having both conductive type layer regions, wherein the one end of the interconnector according to any one of claims 1 to 7 is connected. Solar cells. 9. A double-sided junction type solar cell having both a first conductivity type layer region and a second conductivity type layer region on a light receiving surface side of a first conductivity type semiconductor substrate and a second conductivity type layer on a back surface side. A solar cell, wherein the one end of the interconnector according to any one of claims 1 to 7 is connected. 10. A double-sided junction solar cell having both a first conductivity type layer region and a second conductivity type layer region on each of a light receiving surface side and a back surface side of a first conductivity type semiconductor substrate,
A solar cell, wherein the one end of the interconnector according to any one of claims 1 to 7 is connected. 11. A cover glass adhered to the light receiving surface by a silicone resin, wherein the silicone resin extends so as to cover at least a part of the interconnector except for the connection part. The solar cell according to any one of claims 8 to 10, wherein 12. The other end of the interconnector connected to the double-sided solar cell according to claim 8 is connected to another double-sided solar cell. A method for connecting solar cells.