WO2020096290A1

WO2020096290A1 - Artificial satellite solar cell panel

Info

Publication number: WO2020096290A1
Application number: PCT/KR2019/014772
Authority: WO
Inventors: 김정식; 안기태; 장지영; 전진형
Original assignee: 엘지전자 주식회사
Priority date: 2018-11-05
Filing date: 2019-11-01
Publication date: 2020-05-14
Also published as: KR102589092B1; KR20200051441A

Abstract

The present invention relates to an artificial satellite solar cell panel. A solar cell panel according to one embodiment of the present invention comprises: a plurality of cell strings in which a plurality of artificial satellite solar cells respectively provided therein are connected in series in a first direction by an interconnector, and which are spaced apart from each other in a second direction crossing the first direction; and bushing bars which are extended to be long in the second direction at the ends of the plurality of cell strings, and which are electrically connected to the interconnector connected to the last solar cell of each of the plurality of cell strings so that the plurality of cell strings are electrically connected to each other or are connected to a junction box, wherein: the busing bars comprise a plurality of contact point portions to which the interconnector is connected and connecting parts for mutually connecting a plurality of contact points; a first directional width of the connecting parts of the bushing bars is narrower than a first directional width of the contact point portions; and the connecting parts of the bushing bars comprise first long holes extended to be long in the second direction.

Description

Solar Panel for Satellite

The present invention relates to a solar panel for satellites, and is a study conducted with the support of the Korea Research Foundation-Cosmic Core Technology Development Project (NRF-2017M1A3A3A03016626), funded by the government (Ministry of Science and ICT) in 2018.

Recently, as the depletion of existing energy resources such as petroleum and coal is predicted, interest in alternative energy to replace them is increasing, and accordingly, solar cells that produce electric energy from solar energy are attracting attention.

Such solar cells are widely used as devices for supplying power to satellites that perform specific tasks in extreme environments.

Accordingly, since a solar cell module for a satellite to which a plurality of solar cells is applied is operated by being exposed to an extreme environment, safety and reliability of a solar cell module that can withstand extreme environments rather than manufacturing costs are becoming more important.

In particular, the solar cell module applied to an artificial satellite must withstand vibrations generated by a projectile generated when the satellite is mounted on a projectile and escapes the earth, and after reaching a certain orbit in outer space, the artificial satellite is applied to outer space. After exposure, it must withstand extreme temperatures.

In particular, when the satellite is exposed to the sun's light in outer space, the temperature exceeds 100 ° C due to the radiant heat of the sun's light, is not exposed to the sun's light, and the temperature when it is covered by the shadow of the earth is minus -100 ° C. As a result, the temperature change range in the rainwater space reaches at least 200 ° C.

In particular, when the satellite is covered by the shadow of the moon or the earth and has a sub-zero temperature, there is no particular problem in the efficiency of the solar cell, but when the satellite is exposed to the sun and exceeds 100 ° C due to the radiant heat of the sun, the solar cell There is a problem that the efficiency of can be lowered.

Accordingly, in the case of a conductor such as an interconnector or a busing bar provided in a solar panel provided in an artificial satellite, thermal expansion and the resulting thermal expansion stress may be a problem in an extreme space environment where temperature change is very large.

In this extreme environment, once a failure occurs, it cannot be repaired, so the reliability of the solar module that supplies power to the satellite is more important.

An object of the present invention is to provide a solar panel for satellite with improved reliability. More specifically, the object of the present invention is to provide a solar panel for satellites that can minimize the disconnection between the busing bar and the interconnector by minimizing the thermal expansion rate and the thermal expansion stress of the busing bar.

In the solar panel according to an example of the present invention, a plurality of cell strings in which a plurality of satellite solar cells provided in each are connected in series in a first direction by an interconnector and spaced apart from each other in a second direction crossing the first direction ; And disposed at the ends of each of the plurality of cell strings, elongated in a second direction, and electrically connected to an interconnector connected to the last solar cell of each of the plurality of cell strings, wherein the plurality of cell strings are electrically connected to each other, It includes; a busing bar connected to the junction box, the busing bar includes a connection portion that connects each other between a plurality of contact point portions and a plurality of contact points to which an interconnector is connected, the width of the first direction of the connecting portion of the busing bar is The contact point portion is narrower than the width in the first direction, and the connecting portion of the bussing bar has a first long hole extending in the second direction.

Here, each of the plurality of solar cells for satellites is a semiconductor substrate on which a pn junction is formed, a first electrode on the front surface of the semiconductor substrate, a second electrode on the back surface of the semiconductor substrate, and a cover glass having the same area as the semiconductor substrate on the front surface of the semiconductor substrate. Is attached, the cover glass is attached to the front surface of each semiconductor substrate provided in each solar cell, and is spaced apart from each other between each semiconductor substrate.

Here, the interconnector is connected to the first electrode between the cover glass of each solar cell and the semiconductor substrate, and is connected to the second electrode provided on the rear surface of the adjacent solar cell in the first direction, and each solar cell is in the first direction The length of the second direction may be longer than the length of.

In addition, the length of the second direction of the busing bar may be greater than the length of the second direction of each solar cell or 1.5 times or more the length of the second direction of each solar cell.

Alternatively, the length of the second direction of the busing bar may be the same as or longer than the length between both ends of the second direction of the cell strings of the plurality of cell strings.

The busing bar may include a second long hole extending in a second direction in the contact point portion.

In addition, the second long hole provided in the contact point portion of the busing bar may be provided in a plurality of spaced apart in the first direction.

In addition, the center positions of the plurality of second long holes spaced apart in the first direction may be alternately positioned in the second direction.

Also, the length of the first long hole may be longer than the length of the second long hole.

In addition, the solar cell panel for a satellite includes a solar cell array substrate that adheres to the rear surface of a plurality of cell strings to support a plurality of solar cells and emit radiant heat emitted from the sun. The and connecting portion may be adhered to the solar cell array substrate.

In the solar panel for satellites according to an example of the present invention, the bussing bar has a connection portion having a relatively smaller width than the contact point portion, and a first long hole in the connection portion to minimize the thermal expansion rate and thermal expansion stress of the busing bar, thereby The disconnection between the bar and the interconnector can be prevented.

1 schematically shows an artificial satellite 1 to which a solar panel 10 for an artificial satellite is applied according to an example of the present invention.

FIG. 2 is a perspective view of the solar panel 10 for satellites provided in the wing portion of the satellite 1 in FIG. 1.

3 is an enlarged view of a portion K1 in FIG. 2.

4 and 5 are diagrams for explaining the structure of the solar cell 200 for the satellite shown in FIG.

6 is a view for explaining the structure of a cell string of a solar panel according to the present invention and a bussing bar connected to each cell string.

FIG. 7 is an enlarged view of upper portions of the first and second strings in FIG. 6A in order to more specifically describe the busing bar according to an example of the present invention.

FIG. 8 is a cross-sectional view when the solar panel shown in FIG. 7 is viewed from above in the second direction.

9 is a view for explaining the form in which the conventional busing bar is adhered to the solar cell array substrate with the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and like reference numerals are assigned to similar parts throughout the specification.

In the drawings, the thickness is enlarged to clearly express the various layers and regions. When a portion of a layer, film, region, plate, or the like is said to be “above” another portion, this includes not only the case “directly above” other portions, but also other portions in between. Conversely, when one part is "just above" another part, it means that there is no other part in the middle. Also, when a part is formed "overall" on another part, it means that not only is formed on the entire surface (or front side) of the other part, but also not formed on a part of the edge.

In addition, hereinafter, the meaning that the thickness, width, or length of a component is the same is compared with the thickness, width, or length of a second component, in which the thickness, width, or length of a first component is considered in consideration of process errors. Therefore, it means that it is in the error range of 10%.

Then, the present invention will be described with reference to the accompanying drawings.

1 is a simplified illustration of an artificial satellite 1 to which a solar panel 10 for an artificial satellite is applied according to an example of the present invention, and FIG. 2 is for an artificial satellite provided in a wing portion of the artificial satellite 1 in FIG. 1. 3 is a perspective view of the solar panel 10, and FIG. 3 is an enlarged view of a portion K1 in FIG.

As illustrated in FIG. 1, the solar panel 10 for an artificial satellite according to an example of the present invention can be applied by being located at a wing portion of the satellite 1 to supply power available to the satellite 1. .

To this end, the solar panel 10 for the satellite located in the wing portion of the satellite 1, as shown in Figure 2, the solar cell array substrate 100 and the plurality of solar cells 200 in the first direction ( It may include a plurality of cell strings connected in series in x) and spaced apart from each other in a second direction (y) intersecting the first direction (x).

Here, the plurality of solar cells 200 included in each of the plurality of cell strings may be applied to a satellite solar cell 200 applicable to an extreme space environment in which a temperature change of at least 200 ° C due to radiant heat of solar light is applied. .

Unlike the typical solar cell 200 used in the earth's atmosphere, the solar cell 200 for satellites has a metal material having an extremely low thermal expansion coefficient, an electrode material, an interconnector 260 material, and a lead wire of each solar cell 200. It can be used as a material.

In addition, in outer space, there is no influence due to external wind or climate unlike in the earth, and there is no need for a transparent glass substrate covering the entire plurality of solar cells 200, and a transparent glass substrate is provided on the front surface of the solar cells 200. Even if positioned, the glass substrate may not cover the plurality of solar cells 200 and the interconnector 260 (not shown) in common.

That is, although the transparent glass substrate covers each solar cell 200, the interconnector 260 may be exposed to outer space without being covered by the glass substrate.

Therefore, each solar cell 200 includes a cover glass (not shown), a front electrode (not shown), a semiconductor layer (not shown) and a back electrode (not shown) for photoelectric conversion, and each front electrode includes The interconnector 260 (not shown) may be electrically connected.

In addition, each of the interconnectors 260 (not shown) may connect a plurality of solar cells 200 in series in a first horizontal direction (x) or a second horizontal direction (y).

As illustrated in FIG. 2, a plurality of satellite solar cells 200 may be spaced apart in a first horizontal direction (x) and a second horizontal direction (y).

2 and 3, the solar cell array substrate 100 supports a plurality of solar cells 200 and emits radiant heat emitted from the sun.

The rear surfaces of the plurality of cell strings may be adhered to the front surface of the solar cell array substrate to support the plurality of cell strings.

More specifically, for this purpose, the rear surfaces of the plurality of solar cells 200 included in the plurality of cell strings are adhered to the front surface of the solar cell array substrate 100 through the cell adhesive 400, as shown in FIG. 3. Can be.

4 is a perspective view for explaining the structure of the solar cell 200 for satellite shown in FIG. 3, and FIG. 5 is a first direction (x) for explaining the structure of the solar cell 200 for satellite shown in FIG. ) It is a cross-sectional view.

4 and 5, the solar cell 200 for satellite includes a semiconductor substrate 240, a front electrode 230, a rear electrode 250, a cover glass 210, and an interconnector 260. can do.

Here, the semiconductor substrate 240 may form a pn junction therein to generate solar light incident from the outside, and as shown in FIG. 4 on the front surface of the semiconductor substrate 240, a first horizontal direction The front electrode 230 may be formed including a plurality of finger electrodes extended in (x) and a busbar electrode extending in the second direction (y) to connect the plurality of finger electrodes to each other.

In addition, the rear electrode 250 may be entirely formed on the rear surface of the semiconductor substrate 240.

As shown in FIG. 5, one end of the interconnector 260 is electrically connected to the busbar electrode of the front electrode 230 and the other end is elongated in the first horizontal direction (x), as shown in FIG. 5. Can be withdrawn outside.

The cover glass 210 may be adhered to the front surface of the semiconductor substrate 240 on which the front electrode 230 is formed using a cover glass adhesive 220 such as transparent epoxy.

4 and 5, the area of the cover glass 210 may be formed by bonding the cover glass adhesive 220 to the front surface of the semiconductor substrate 240 in the same area and shape as the semiconductor substrate 240. have. Alternatively, the difference between the area of the cover glass 210 and the area of the semiconductor substrate 240 may be within 10%.

Therefore, before the plurality of satellite solar cells 200 are formed as a cell string, each of the satellite solar cells 200 is one of electrodes having different polarities provided in the plurality of satellite solar cells 200. Interconnector 260 is provided to be connected to an electrode having polarity (eg, front electrode), and a cover glass 210 may be attached to the front surface of each of the plurality of satellite solar cells 200. .

Accordingly, when the plurality of solar cells 200 are formed in a cell string by being long connected in the first direction (x), the first sun in the first and second solar cells 200 adjacent to each other in the first horizontal direction (x) The cover glass 210 attached to the battery 200 and the cover glass 210 attached to the second solar cell 200 may be spaced apart from each other between the first and second solar cells 200.

Here, each solar cell 200 may have a longer length (Ly) in the second direction (y) than a length (Lx) in the first direction (x).

As described above, the first direction length Lx of the solar cell 200 is relatively thinned, so that when the cell strings have the same length, more solar cells 200 are provided in each cell string, thereby outputting the solar panel. The voltage can be further increased.

Hereinafter, each cell string formed of the above-described satellite solar cell 200 and both ends of each cell string may be connected to the bussing bar.

6 is a view for explaining the structure of a cell string of a solar panel according to the present invention and a bussing bar connected to each cell string, FIG. 6 (a) is a shape looking at the solar panel from above, FIG. (b) is an enlarged view of the portion K2 shown in (a) of FIG. 6, and (c) of FIG. 6 is a view of the portion K2 shown in (a) of FIG. 6 from the side in the second direction (y). It shows the vertical cross section of the time.

FIG. 7 is an enlarged view of upper portions of the first and second strings in FIG. 6A in order to more specifically describe the busing bar according to an example of the present invention, and FIG. 8 is a view illustrated in FIG. 7 The cross section is shown when the battery panel is viewed from above in the second direction (y).

As shown in Figure 6 (a), an example of the solar panel according to the present invention, each of the plurality of cell strings (ST1 ~ STn) are located in the first direction (x) long, the first direction (x) and A plurality of cell strings ST1 to STn may be spaced apart from each other in the crossing second direction y.

For example, each of the plurality of cell strings ST1 to STn may have a plurality of satellite solar cells 200 provided in each of them connected in series in the first direction x by the interconnector 260.

The busing bar 300 may be disposed to extend in the second direction (y) at the ends of each of the cell strings ST1 to STn.

The busing bar 300 is electrically connected to the interconnector 260 connected to the last solar cell 200 of each of the plurality of cell strings ST1 to STn, so that the plurality of cell strings ST1 to STn are electrically connected to each other. It may be connected to a junction box (not shown).

For example, the first cell string ST1 and the second cell string ST2 may be connected to each other in series by a busing bar 300 that is disposed to extend in the second direction y.

The second direction length L300 of the busing bar 300 is greater than the length Ly of the second direction of each solar cell 200 in FIGS. 6 and 7 or the length of the second direction of each solar cell 200 It may be 1.5 times or more of (Ly).

Alternatively, the length of the second direction L300 of the busing bar 300 may be equal to or longer than the length between both ends of the second direction y of the at least two cell strings among the plurality of cell strings ST1 to STn.

For example, in FIGS. 6 and 7, the length L300 of the second direction of the busing bar 300 is directly adjacent to each other, but between both ends of the second direction y of the two cell strings spaced apart in the second direction y. The same case as the length (WTS) is shown as an example.

The busing bar 300 may include a plurality of contact point portions 310 and a connection portion 320 as illustrated in FIGS. 6 and 7.

6 (b) and (c) of the contact point portion 310 of the busing bar 300, the interconnector 260 connected to the last solar cell 200 of each cell string, as shown in FIG. Can be connected.

Here, as shown in Figure 6 (c), the interconnector 260 connected to the last solar cell 200 of each cell string will be located on the front of the contact point portion 310 of the busing bar 300 Can be. [For reference, the front surface of the busing bar 300 refers to a surface in which light is incident from the solar panel for satellites, and the rear surface of the busing bar 300 is bonded to the solar cell array substrate. It means noodles.]

The connecting portion 320 of the busing bar 300 is located between the contact point portions 310 as the rest of the busing bar 300 except for the contact point portion 310 to connect the plurality of contact point portions 310 to each other. have.

As shown in FIGS. 6 and 7, the contact point portion 310 and the connection portion 320 of the busing bar 300 have a first direction width W320 of the connection portion 320 of the busing bar 300. It is formed narrower than the first direction width W310 of the contact point portion 310 so that it can be easily distinguished visually.

Here, FIGS. 6 and 7 are illustrated as an example in which the first direction width W310 of the contact point portion 310 is approximately twice that of the first direction width W320 of the connection part 320, but the contact point The first direction width W310 of the portion 310 may be formed between 1.5 times to 2.5 times the first direction width W320 of the connection part 320.

In this way, the first direction width (W310) of the contact point portion 310 is made larger than the first direction width (W320) of the connection portion 320, thereby increasing the physical adhesion between the busing bar (300) and the interconnector (260). By sufficiently securing the electrical properties, the thermal expansion coefficient that expands and contracts in the second direction (y), which is the longitudinal direction of the busing bar 300, is relatively small by making the width (W320) of the first direction of the connection part (320) relatively small. While reducing, it is possible to relieve the thermal expansion stress of the busing bar (300).

Accordingly, a difference in thermal expansion in the second direction (y) of the busing bar 300 may occur due to an excessive temperature difference generated in space, thereby increasing the thermal expansion stress of the busing bar 300 and the busing bar 300 ) As the number of thermal expansion and thermal contraction increases, physical bonding between the busing bar 300 and the interconnector 260 may drop, and the present invention can be reduced.

In order to further reduce the thermal expansion stress of the busing bar 300, the connection part 320 may include a first long hole H1 extending in the second direction (y).

In addition, a second long hole H2 extending in the second direction y may be provided at the contact point portion 310. When the interconnector 260 is welded to the second long hole H2 provided in the contact point portion 310, the thermal expansion stress may be reduced to further reduce the welding defect rate.

In addition, the second long hole H2 provided in the contact point portion 310 of the busing bar 300 may be spaced apart in the first direction x to be provided in plural.

Here, the length LH2 of the plurality of second long holes H2 spaced apart in the first direction x may be the same or different from each other, and the length LH2 of the plurality of second long holes H2 spaced apart in the first direction x may be the same. The central positions may be the same or may be located alternately in the second direction (y).

Also, the length LH1 of the first long hole H1 may be formed to be longer than the length LH2 of the second long hole H2.

As described above, the busing bar 300 of the solar panel for satellite according to the present invention is provided with a first long hole H1 in the connection portion 320, thereby reducing the thermal expansion stress of the busing bar 300, thereby In a space environment, a phenomenon in which the busting bar 300 and the interconnector 260 are disconnected due to thermal expansion stress of the busing bar 300 may be minimized.

In addition, as shown in FIG. 8, the contact point portion 310 and the connection portion 320 of the busing bar 300 may be adhered to the solar cell array substrate by the cell adhesive 400.

As shown in FIG. 8, when the contact point portion 310 of the busing bar 300 as well as the connection portion 320 are bonded to the solar cell array substrate by the cell adhesive 400, the thermal expansion rate of the busing bar 300 is further increased. By reducing, the thermal expansion stress of the busing bar 300 can be further reduced.

However, the busing bar 300 applied to the conventional solar panel for satellites, as shown in FIG. 9, adheres only the portion of the cell string connected to the interconnector 260 of the cell string to the solar cell array substrate with the cell adhesive 400. And between the cell string and the cell string, the busing bar 300 and the solar cell array substrate 100 had a structure spaced apart from each other.

This was to prevent the disconnection between the busing bar 300 and the interconnector 260 due to the thermal expansion stress of the busing bar 300, but nevertheless, the conventional busing bar 300 is the sun due to the thermal expansion stress. There is a problem in that the adhesion between the battery array substrate is poor, and the adhesion between the busing bar 300 and the interconnector is weakened, and the busing bar 300 and the interconnector 260 are disconnected.

However, in the case of the present invention, as shown in FIG. 8, the contact point portion 310 of the busing bar 300 as well as the connecting portion 320 are adhered to the solar cell array substrate, thereby thermal expansion of the busing bar 300 It is possible to further suppress the difference in rate, thereby reducing the thermal expansion stress of the busing bar 300.

In order to further reduce the thermal expansion stress of the busing bar 300 itself, the material of the busing bar 300 may be formed of an alloy containing iron (Fe), nickel (Ni), and cobalt (Co) as a main component. Can be.

For example, iron (Fe) content may be mixed between 50% to 60% by weight, nickel (Ni) between 25% to 35% by weight, and cobalt (Co) between 15% to 20% by weight, , In addition, chromium (Cr) and the like may be further contained in a small amount.

Accordingly, the coefficient of thermal expansion of the busing bar 300 itself can be reduced to a level similar to that of glass or alumina.

As described above, the present invention can minimize the thermal expansion rate of the busing bar 300 in an extreme space environment where temperature changes are extremely severe, thereby preventing disconnection between the busing bar 300 and the interconnector 260.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims

A plurality of cell strings in which a plurality of satellite solar cells provided in each are connected in series in a first direction by an interconnector and spaced apart from each other in a second direction intersecting the first direction; And

The plurality of cell strings are disposed to extend in the second direction at each end, and are electrically connected to an interconnector connected to the last solar cell of each of the plurality of cell strings, so that the plurality of cell strings are electrically connected to each other. Included, or connected, the busing bar connected to the junction box,

The busing bar includes a plurality of contact point portions to which the interconnector is connected and a connection portion connecting the plurality of contact points to each other,

The width in the first direction of the connecting portion of the busing bar is narrower than the width in the first direction of the contact point portion,

The connection portion of the bus bar is a solar panel for a satellite having a first long hole extending in the second direction.
In claim 1,

Each of the plurality of satellite solar cells

a semiconductor substrate on which a p-n junction is formed,

A first electrode on the front surface of the semiconductor substrate,

A second electrode on the back side of the semiconductor substrate, and

A cover glass having the same area as the semiconductor substrate is attached to the front surface of the semiconductor substrate,

The cover glass is attached to the front surface of each of the semiconductor substrates provided in each of the solar cells, spaced apart from each other between each of the semiconductor substrates satellite solar panel.
In claim 2,

The interconnector is connected to the first electrode between the cover glass of each solar cell and the semiconductor substrate, and is connected to a second electrode provided on the rear surface of the solar cell immediately adjacent in the first direction,

Each solar cell is a solar panel for a satellite having a longer length in the second direction than a length in the first direction.
In claim 1,

The length of the second direction of the busing bar is greater than or equal to the length of the second direction of each solar cell, or the solar panel for a satellite of 1.5 times or more the length of the second direction of each solar cell.
In claim 1,

The length of the second direction of the busing bar is equal to or longer than a length between both ends of the second direction of at least two cell strings of the plurality of cell strings.
In claim 1,

The bus bar is a solar panel for a satellite having a second long hole extending in the second direction to the contact point portion.
In claim 6,

The second long hole provided in the contact point portion of the busing bar is spaced apart in the first direction is provided with a plurality of satellite solar panel.
In claim 6,

The center position of the plurality of second long holes spaced apart in the first direction is located in the second direction staggered with each other, a solar panel for a satellite.
In claim 6,

The length of the first long hole is a solar panel for satellites longer than the length of the second long hole.
In claim 1,

The solar panel for the satellite

It includes; a solar cell array substrate for supporting the plurality of solar cells and emitting radiant heat emitted from the sun by attaching a front surface to the rear surfaces of the plurality of cell strings.

The contact point portion and the connecting portion of the busing bar are a solar panel for a satellite that is bonded to the solar cell array substrate.