JP2010123616A - Solar cell panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a solar cell panel readily suppressing occurrence of arc discharge in a high plasma density environment and readily increasing the mounting efficiency of solar cells and decreasing the weight of the same. <P>SOLUTION: In the solar cell panel 20A including a substrate 1, the plurality of solar cells 3 mounted on an upper surface 1a of the substrate and a light-transmissive film 10A covering the plurality of solar cells, by covering the respective solar cells, the upper surface of the substrate and a side surface 1b of the substrate with the light-transmissive film and by fixing the light-transmissive film to the substrate on a lower surface 1c of the substrate, formation of triple junction in the high plasma density environment is prevented to suppress generation of the arc discharge. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solar cell panel, and more particularly to a solar cell panel in which the occurrence of arc discharge is suppressed even in an environment where the plasma density is high.

  Many spacecraft such as artificial satellites and spaceships have been launched in outer space. In recent years, spacecrafts have become more sophisticated, and accordingly, the supply of high power to the spacecraft has been required. Since a solar cell panel is used as a power source in a spacecraft, development of a solar cell panel capable of supplying a large amount of power is required. For example, in order to realize a large spacecraft that requires a large power of 1 MW level, it is considered that power generation with a high voltage of at least 300 to 400 V or more is required with one solar battery panel.

  For example, in outer space where the plasma density is high, such as the Earth's low orbit, the solar cell has a negative potential with respect to the surrounding plasma due to the mass difference between electrons and ions. When the solar cell has a negative potential of 100 to 200 V or more with respect to the surrounding plasma, a conductor such as a solar cell or an interconnector connecting the solar cells, an insulator such as a cover glass covering the solar cell, and a plasma space ( It is known that arc discharge occurs at a triple junction (hereinafter referred to as “triple junction”) where three members of (space) contact.

  Therefore, in order to realize a solar cell panel that generates power at a high voltage of 300 to 400 V or more in outer space with a high plasma density, it is necessary to suppress the arc discharge. For this reason, for example, in a solar cell panel (solar array) described in Non-Patent Document 1, a triple junction is obtained by using a translucent film having radiation resistance as an ion barrier and covering the surface of the solar cell array with the translucent film. The arc discharge is suppressed by preventing the formation of. In this solar cell panel, it has been confirmed that arc discharge does not occur even when the solar cell is charged to a negative potential of 800 V with respect to the surrounding plasma.

S. Hosoda, et al, “Development of 400V solar array technology for LEO spacecraft”, 9th Spacecraft Charging Technology Conference, Tsukuba, Japan, 2005.

  In the solar cell panel described in Non-Patent Document 1, since the end of the translucent film is fixed to the substrate surface on the side where the solar cell is mounted, plasma is generated from the gap between the substrate and the translucent film. The distance from the end of the translucent film to the nearest solar cell must be sufficiently large so that the plasma does not reach the periphery of the solar cell even if it penetrates. However, in order to increase the distance sufficiently, a sufficiently large non-mounting area must be secured outside the mounting area of the solar cell on the substrate, and the mounting efficiency of the solar cell on the solar cell panel is increased. As it decreases, the mass of the solar cell panel increases.

  The present invention has been made in view of the above circumstances, and obtains a solar cell panel that is easy to suppress the occurrence of arc discharge in an environment with a high plasma density and that is easy to reduce the weight and improve the mounting efficiency of the solar cell. For the purpose.

  The solar cell panel of the present invention that achieves the above object comprises a substrate, a plurality of solar cells mounted on the upper surface of the substrate, and a translucent film covering the plurality of solar cells, and a translucent film Is characterized in that it covers a plurality of solar cells, the upper surface of the substrate, and the side surface of the substrate, and is fixed to the substrate by the lower surface of the substrate.

  In the solar cell panel of the present invention, since the translucent film is fixed to the substrate on the lower surface of the substrate, the translucency can be obtained without providing a wide non-mounting area outside the mounting area of the solar cell on the substrate. It is easy to increase the distance from the fixed part of the film to the solar cell. Therefore, it is also easy to prevent the plasma that has entered from the gap between the substrate and the edge of the translucent film from reaching the periphery of the solar cell and forming a triple junction. Therefore, according to the present invention, it is possible to obtain a solar cell panel that can easily suppress the occurrence of arc discharge in an environment with a high plasma density, and that can easily reduce the weight and improve the mounting efficiency of the solar cell.

  Hereinafter, embodiments of the solar cell panel of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view schematically showing an example of the solar cell panel of the present invention, and FIG. 2 is a bottom view schematically showing the solar cell panel shown in FIG. A solar cell panel 20A shown in these drawings includes a substrate 1 having a rectangular flat plate shape, a plurality of solar cells 3, 3... Mounted on the upper surface 1a of the substrate 1, and a solar cell covering each solar cell 3. 3 is provided with a translucent film 10 </ b> A that prevents ions from reaching the periphery of 3.

  Each solar cell 3 is fixed to the upper surface 1 a of the substrate 1 by an adhesive (not shown), and the adjacent solar cells 3 and 3 are electrically connected to each other by an interconnector 5. Further, a cover glass 7 is disposed on the light receiving surface (upper surface) of each solar cell 3 for the purpose of preventing deterioration of the solar cell 3.

  The translucent film 10 </ b> A has light transmissivity in the wavelength range used for power generation in the solar cell 3, and has an ion barrier property and an electrical insulation functioning as a plasma barrier, and the translucent film 10 </ b> A is The planar shape when expanded is, for example, a quadrangle. The translucent film 10A covers each solar cell 3, the upper surface 1a of the substrate 1, and the side surface 1b of the substrate 1, and is fixed to the substrate 1 by the lower surface 1c of the substrate 1 with an adhesive 15 (see FIG. 2). Has been.

  In the illustrated solar cell panel 20A, the central portion of the lower surface 1c of the substrate 1 is exposed in a rectangular shape without being covered with the translucent film 10A, and the edge of the translucent film 10A is exposed from the edge of the central portion. The adhesive material 15 is coated in a rectangular frame shape over the top surface of the part. The translucent film 10 </ b> A is fixed to the lower surface 1 c of the substrate 1 by the adhesive 15. As the translucent film 10A, for example, a film made of an ethylene / tetrafluoroethylene copolymer resin is used, and the thickness thereof is appropriately determined in consideration of the light transmittance, mechanical strength, etc. of the translucent film 10A. Selected.

  When the edge of the translucent film 10A undulates on the lower surface 1c side of the substrate 1 when the substrate 1 and each solar cell 3 are covered with the translucent film 10A, the edge of the translucent film 10A and the substrate A gap is likely to be generated between the lower surface 1c of the first plasma, and when such a gap is generated, plasma is likely to enter from the gap. Therefore, from the viewpoint of suppressing the occurrence of arc discharge in an environment where the plasma density is high, the edge of the translucent film 10 </ b> A is prevented from undulating as much as possible on the lower surface 1 c side of the substrate 1. It is preferable to cover the substrate 1 and each solar cell 3 with the translucent film 10A so that the gap between the upper surface (the upper surface of each cover glass 7) and the translucent film 10A becomes small.

  When the translucent film 10A is in contact with the edge (ridge) on the upper surface 1a side or the edge (ridge) on the lower surface 1c side of the substrate 1, the solar cell panel 20A is repeatedly exposed to a heat cycle. In addition, the translucent film 10A may be broken from the portion in contact with the edge portion due to the difference in thermal expansion coefficient between the substrate 1 and the translucent film 10A. From the viewpoint of preventing such tearing of the translucent film 10A, the translucent film 10A is separated from the side surface 1b of the substrate 1 by giving the translucent film 10A slack on the side surface 1b side of the substrate 1. Thus, it is preferable to cover the substrate 1 and each solar cell 3 with a translucent film 10A.

In the solar cell panel 20A having the above-described configuration, the shortest distance from the fixing location of the translucent film 10A to the outer edge of the outermost solar cell 3 along the substrate surface is from the fixing location of the translucent film 10A. The distance L ₁ to the nearest edge portion on the lower surface 1 c of the substrate 1, the thickness t of the substrate 1, and the distance from the nearest edge portion on the upper surface 1 a of the substrate 1 to the outer edge of the outermost solar cell 3. This is the sum of L ₂ (see FIG. 1). Therefore, without providing a non-mounting area wider on the outside of the mounting area of the solar cell 3 in the substrate 1, in other words even shorter the distance L _2, the fixed portion of the light-transmitting film 10A It is easy to increase the distance from each to the solar cells 3.

  As a result, even if the plasma enters from the gap between the lower surface 1c of the substrate 1 and the edge of the translucent film 10A, the plasma reaches the periphery of the solar cell 3 and a triple junction is formed. It is easy to prevent. Therefore, in solar cell panel 20A, it is easy to suppress the occurrence of arc discharge in an environment with a high plasma density. Moreover, since it is not necessary to provide a wide non-mounting area on the substrate 1, it is easy to reduce the weight and improve the mounting efficiency of the solar cell.

On the other hand, as in the solar cell panel described in Non-Patent Document 1, in the case where the end of the translucent film is fixed to the substrate surface on the side where the solar cell is mounted, the solar cell panel shown in FIG. 25, the formation of a triple junction must be prevented by sufficiently increasing the distance L ₃ from the edge portion on the upper surface 1a of the substrate 1 to the outer edge of the nearest solar cell 3, so that the solar cell 3 As the mounting efficiency decreases, the mass of the solar cell panel 25 increases. 6 that have the same functions as those shown in FIG. 1 or 2 are denoted by the same reference numerals as those used in FIG. 1 or FIG.

Embodiment 2. FIG.
In the solar cell panel of this invention, a translucent film can also be fixed to a board | substrate with the adhesive agent applied to the spot shape in multiple places. For example, through holes are provided at a plurality of locations on the edge of the translucent film, an adhesive is applied from the individual through holes to the periphery of the through holes, and the translucent film is formed on the lower surface of the substrate. Fixed.

  FIG. 3 is a cross-sectional view schematically showing an example of a solar cell panel in which a translucent film is fixed to the lower surface of a substrate by an adhesive applied in a spot shape at a plurality of locations, and FIG. It is sectional drawing which expands and shows roughly the fixed location of the translucent film in the shown solar cell panel, FIG. 5: Application | coating of the adhesive agent performed in producing the solar cell panel shown in FIG. It is a perspective view which shows a process roughly.

  In the solar cell panel 20B shown in FIG. 3, each solar cell 3, the upper surface 1a of the substrate 1, and the side surface 1b of the substrate 1 are covered with a translucent film 10B in which through holes TH are provided at a plurality of locations at the edge. 1 except that the translucent film 10B is fixed to the substrate 1 by the lower surface 1c of the substrate 1 by the adhesive 15 applied to each through hole TH. It has the composition of. Among the constituent elements shown in FIG. 3, the constituent elements other than the translucent film 10 </ b> B are denoted by the same reference numerals as those used in FIG. 1 and the description thereof is omitted.

  The translucent film 10B has light transmissivity in the wavelength region used for power generation in the solar cell 3 and a plasma barrier, as with the translucent film 10A in the solar cell panel 20A shown in FIG. The planar shape when the translucent film 10B is expanded is, for example, a quadrangle. The planar shape of each through hole TH provided at the edge of the translucent film 10B can be selected as appropriate, such as a circle, an ellipse, and a rectangle.

  The adhesive 15 is applied and cured from each through hole TH to the periphery of the through hole TH. Therefore, as shown in FIG. 4, the cross section of the adhesive at each coating location exhibits a reverse mushroom shape. By appropriately selecting the size of each through hole TH and the coating amount and coating area of the adhesive 15, it is possible to easily secure the bonding strength and the bonding area required for fixing the translucent film 10B. Can do.

  As shown in FIG. 5, the coating of the adhesive 15 covers each solar cell 3, the upper surface 1 a (see FIG. 3) of the substrate 1, and the side surface 1 b of the substrate 1 with the translucent film 10 </ b> B. After covering the edge of the lower surface 1c of the substrate, the coating can be performed using a coating apparatus such as the dispenser 30 with the lower surface 1c side of the substrate 1 facing upward. In FIG. 5, the application direction of the adhesive from the dispenser 30 is indicated by a white arrow A, and the adhesive 15 has already been applied to 10 of the 12 through holes TH in total. In the figure, the adhesive 15 is smudged so that the adhesive 15 can be easily distinguished from others.

  The solar cell panel 20B configured as described above is easy to suppress the occurrence of arc discharge in an environment where the plasma density is high and is lightened and reduced for the same reason as in the solar cell panel 20A shown in FIG. There is a technical effect that it is easy to improve the mounting efficiency of the solar cell. Moreover, since the coating amount of the adhesive can be reduced as compared with the solar cell panel 20A shown in FIG. 1, there is also a technical effect that the manufacturing cost can be reduced and the productivity can be easily improved.

  The solar cell panel of the present invention has been described with reference to the embodiment, but as described above, the present invention is not limited to the above embodiment. The solar cell panel of the present invention is basically good as long as the translucent film covers each solar cell, the upper surface of the substrate, and the side surface of the substrate, and is fixed to the substrate on the lower surface of the substrate, Other than the basic configuration can be changed as appropriate. For example, each solar cell panel 20A, 20B (see FIG. 1 or FIG. 3) mentioned in the embodiment is an individual solar cell 3 covered with a cover glass 7, but the cover glass 7 is omitted. Is also possible. Further, the planar shape of the substrate 1 can be selected as appropriate.

  The translucent film only needs to have an ion barrier property that functions as a plasma barrier and an electrical insulating property in the wavelength range used for power generation in a solar cell, and an electrical insulating property. The planar shape, thickness, etc. can be selected as appropriate. As in the solar cell panel described in the second embodiment, when a plurality of through holes to which the adhesive is applied are provided at the edge of the translucent film, the total number of through holes and the distance between adjacent through holes are The interval and the like can be selected as appropriate.

  Further, it is not essential to partially expose the lower surface of the substrate, and the entire lower surface can be covered with a light-transmitting film. In fixing the translucent film to the substrate on the lower surface of the substrate, for example, a frame-shaped fixing member is used together with an adhesive, and the edge of the translucent film is pressed to the lower surface side of the substrate with the fixing member. In this state, the edge of the translucent film and the fixing member can be fixed to the lower surface of the substrate with an adhesive. The present invention can be variously modified, modified, combined, etc. other than those described above.

  The solar cell panel of the present invention is suitable as a solar cell panel used in an environment having a high plasma density, for example, a solar cell panel used in a spacecraft orbiting low earth orbit.

It is sectional drawing which shows roughly an example of the solar cell panel of this invention. FIG. 2 is a bottom view schematically showing the solar cell panel shown in FIG. 1. It is sectional drawing which shows roughly the example of what the translucent film was fixed to the lower surface of a board | substrate among the solar cell panels of this invention with the adhesive agent apply | coated to multiple places in the spot form. It is sectional drawing which expands and shows schematically the fixed location of the translucent film in the solar cell panel shown in FIG. It is a perspective view which shows roughly the coating process of the adhesive agent performed in producing the solar cell panel shown in FIG. It is sectional drawing which shows roughly the solar cell panel which fixed the edge of the translucent film to the board | substrate surface by the side in which the solar cell is mounted.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 1a The upper surface of a board | substrate 1b The side surface of a board | substrate 1c The lower surface of a board | substrate 3 Solar cell 5 Interconnector 7 Cover glass 10A, 10B Translucent film 15 Adhesive 20A, 20B Solar cell panel TH Through-hole

Claims (6)

A substrate, a plurality of solar cells mounted on the upper surface of the substrate, and a translucent film covering the plurality of solar cells,
The translucent film covers the plurality of solar cells, the upper surface of the substrate, and the side surface of the substrate, and is fixed to the substrate with the lower surface of the substrate.   The solar cell panel according to claim 1, wherein the translucent film is fixed to the lower surface of the substrate with an adhesive. The translucent film has a plurality of through holes at the edge,
The adhesive is applied from the through hole to the periphery of the through hole, and fixes the translucent film to the lower surface of the substrate.
The solar cell panel according to claim 2.   The solar cell panel according to any one of claims 1 to 3, wherein the translucent film is spaced apart from and covers the side surface of the substrate.   The solar cell panel according to claim 1, wherein the translucent film has electrical insulation.   The solar cell panel according to claim 1, wherein the translucent film is made of an ethylene / tetrafluoroethylene copolymer resin.

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