JP2001284627A - Method for installing solar cell and generating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a method to respond to such a demand that a coating material for coating and protecting a solar cell is decreased to reduce a price of the solar cell, and a fixing member and a support member for installing the solar cell are decreased to reduce an installation cost, and it is possible to exchange when the coating material is deteriorated, and the coating material and the solar cell can be readily separated and discarded. SOLUTION: A liquid having the translucency and hydrophobicity or water is stored, and a solar cell is sunk in this liquid or water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for installing a solar cell, and more particularly, to a method for installing a solar cell, wherein the solar cell is submerged in a liquid.

[0002]

2. Description of the Related Art Conventionally, solar cells have been widely used as clean and non-depleting energy sources.
Although various researches have been made on the development of the solar cell itself, the development of solar cells that are suitable for installation on the ground and on a roof has been actively conducted.

[0003] Such solar cells have begun to be used in various shapes for various applications, and various requests have been raised.

[0004] Above all, as for a solar cell of the ground installation type, for example, the site is surrounded by a fence or the like like a power plant,
There are the following requests for use in situations where sufficient management can be performed.

[0005] First, it is required to reduce the cost of the solar cell by reducing the number of coating materials for covering and protecting the solar cell element. In addition, for the solar cell element or the solar cell module to which the solar cell element is connected and covered and protected, fixing such as a mount for installation and fixing, and reducing the number of supporting members, the solar cell power generation system There is also a need to reduce installation costs.

[0006] In a situation where the site is surrounded by a fence or the like and sufficient management can be performed, a person other than the administrator cannot easily enter. For this reason, it is conceivable to reduce the material cost of the coating material by reducing the insulation performance in consideration of electric shock prevention, the scratch resistance in consideration of accidental scratching, and the like among the functions performed by the coating material.

[0007] Second, there is also a demand that the coating material be replaceable. If the coating material on the light receiving surface side is deteriorated by being exposed to sunlight and deteriorates in translucency such as yellowing, if the coating material can be replaced, rather than replacing the entire solar cell element, It is much more economical.

Furthermore, if the covering material is replaceable, the solar cell can be easily separated and discarded when the solar cell is discarded.

[0009]

Although there are demands as described above, at present, a solar cell module satisfying all of them and a method of installing the same have not been provided.

[0010] Here, the demand that the coating material can be exchanged can be met to some extent by using a technique such as Japanese Patent Application Laid-Open No. 2-95185. The technique of Japanese Patent Application Laid-Open No. 2-95185 has the following contents.

[0011] A heat medium such as, for example, silicon oil is allowed to flow in a sealed container, and the solar cell element is placed in the heat medium. In this case, the container wall and the heat medium serve as a covering material for the solar cell element, and protect the solar cell element.
Therefore, the container and the heat medium, which are the covering materials, can be replaced according to their life independently of the solar cell element.

However, the present technique is insufficient from the viewpoint of reducing the cost of the solar cell, which is the above demand.

[0013] The transparent sealed container through which the heat medium can flow is exemplified by those made of glass or resin. However, if the container is made with sufficient heat resistance and structural strength, it is not expensive. I can't get it. Furthermore, a support base for installing and fixing such a sealed container is required to have a special shape, which is also considered to be expensive.

Accordingly, it is an object of the present invention to reduce the cost of the solar cell by reducing the number of coating materials for covering and protecting the solar cell element, to reduce the number of fixing members such as a stand for installation and fixing, and to reduce the number of supporting members. And that the coating is replaceable.

[0015]

According to the present invention, a liquid having translucency and hydrophobicity is stored such that the upper surface thereof is in direct contact with the atmosphere, and a solar cell is stored in the liquid. It is characterized by sinking.

Thus, the liquid can function as a covering material for covering and protecting the solar cell element. Therefore, a conventionally used glass plate, a light-transmitting resin, a light-transmitting resin film, and the like can be largely reduced. Further, when the solar cell is submerged in the liquid, the liquid has translucency, so that the solar cell can receive sufficient sunlight to generate power.

Further, since the liquid has hydrophobicity, it does not mix with rainwater and prevents the solar cell from being wrapped in rainwater. This has the following advantages.

If the liquid is not hydrophobic, if the solar cell is made of a material having a property of being easily soluble in water and reacting, the solar cell may be broken. Although it is conceivable that the liquid has hydrophobicity, a solar cell that does not have sufficient water resistance can be used.

When a highly insulating liquid, for example, a highly insulating liquid having an electric resistance larger than the electric resistance of water is used as the liquid, a positive electrode side portion and a negative electrode side portion having a large potential difference are used. Can be arranged close to each other, and the degree of freedom in arranging the solar cells is increased.

On the other hand, when water surrounds the solar cell, a short circuit between the positive electrode and the negative electrode may occur. When the potential difference is small in a short circuit between the positive electrode side portion and the negative electrode side portion that are close to each other via water, the current flowing through the electric resistance of the water is very small and may not affect the power generation performance. However, depending on the arrangement of the solar cells, the positive electrode side part and the negative electrode side part may have a large potential difference and approach each other. At this time, with the electric resistance of water, there is a possibility that a large amount of current flows to lower the power generation performance.

In this case, the highly insulating liquid is as follows.
For example, those having a volume resistivity of about 1 × 10 ⁹ Ω · cm or more can be used. In a normal solar cell installation state, it is considered sufficient to consider the case where a potential difference of about several hundred V is close to about several millimeters. It is considered to be.

In addition, by storing the upper surface of the liquid so as to be in direct contact with the atmosphere, it is possible to reduce the number of coating materials for coating and protecting the solar cell element, thereby reducing the price of the solar cell. it is conceivable that. That is, in order to provide a transparent and light-resistant member in contact with the upper surface of the liquid in order to provide sufficient protection of the solar cell coating, the technique disclosed in Japanese Patent Application Laid-Open No. 2-95185 may be used. This is because it is considered that a sealed container is used as described above, and it is considered that the container becomes expensive.

On the other hand, the present invention is based on the premise that rain falls directly on the liquid that sinks the solar cell, and as a countermeasure, a method of installing an inexpensive solar cell using a hydrophobic liquid. The feature is that it is proposed.

Furthermore, since the solar cell is installed with the configuration of the present invention, the number of fixing members and supporting members of the solar cell can be greatly reduced. That is, in the case of providing a mechanism in which the solar cell does not fly by wind, when providing a liquid having a sufficient weight on the upper side of the solar cell as in the present invention, only the solar cell is submerged in the liquid, and is not particularly fixed. I think it is OK. Therefore, in the present invention, it is possible to eliminate the cost for material for the fixing member, the supporting member such as the gantry, and the operation for fixing.

In addition, even if heat is generated in the solar cell, the liquid is radiated to the liquid, so that there is a high possibility that the temperature of the solar cell can be kept low as compared with a normal installation method. In a normal installation method, air is wrapped around the solar cell, but in the present invention, since the liquid is wrapped in a liquid having better heat transfer than air, the heat of the solar cell is transmitted to the liquid and the solar cell is We can expect that it does not reach high temperature like the installation method. As a result, higher power generation performance than a normal installation method can be expected.

It is preferable that the liquid has a light-transmitting property capable of transmitting 80% or more of sunlight at a wavelength of 0.4 μm to 1.2 μm.

Usually, the cost of the covering material accounts for about 20% or less of the manufacturing cost of the solar cell in many cases. Therefore, the cost of coating materials that can be reduced,
This is because, in consideration of a decrease in the amount of power generation due to a decrease in sunlight incident on the solar cell, if there is no transmission of 80% or more, a sufficient effect according to the present invention may not be obtained.

Here, the wavelength of sunlight is 0.4 μm.
The reason for considering the range from to 1.2 μm is that the spectral sensitivity of a solar cell generally used is generally in this range. For example, there are a crystalline silicon solar cell, an amorphous silicon solar cell, and a gallium arsenide solar cell. Of course, from the above 0.4 μm to 1.2
When a solar cell having a spectral sensitivity outside the range of μm is used, it is preferable to use a liquid having excellent transmittance in the wavelength range.

It is preferable that the liquid has a hydrophobic group that has a hydrophobic group in its structural molecule, so that it is difficult to form a bond with a water molecule. That is, since the liquid does not easily combine with water molecules, rainwater is excluded from around the solar cell to wrap the solar cell, and the above-described operation can be more effectively obtained.

In particular, when the above-mentioned hydrophobic group is an alkyl group or a phenyl group, a readily available material such as ordinary silicone oil is suitable. Is preferred.

When the specific gravity of the liquid is less than 1, there are the following advantages.

The rainwater that has fallen after the installation sinks into the lower layer without being stored on the liquid. Therefore, by providing a mechanism capable of draining rainwater sinking in the lower layer, it is possible to easily maintain a state in which the same amount of liquid of the same material as that at the time of installation is stored on the light receiving surface side of the solar cell.
For this reason, even after rainfall, there is very little concern that rainwater accumulates on the light receiving surface side of the solar cell, changes the amount of incident light, and reduces the amount of power generation. In addition, since the specific gravity of the solar cell is usually greater than 1, the solar cell sinks into this liquid without any special measures, so that the solar cell is excellent in installability.

The liquid has the following advantages because it has a specific gravity larger than 1 and smaller than the specific gravity of the solar cell.

Since the specific gravity of the liquid is greater than 1, rainwater accumulates above the surface of the liquid, and water overflowing from a container or the like is drained. Then, a small amount of rainwater collected above the liquid evaporates and disappears. Therefore, if a means such as a container capable of storing a desired amount of liquid is prepared, many measures are not required for treating rainwater. Furthermore, since the liquid is smaller than the specific gravity of the solar cell, the solar cell easily sinks. Therefore, a holding member or the like is not required to sink the solar cell into the liquid, so that the installation cost is low.

Preferably, the refractive index of the liquid is smaller than 2.6.

As described above, in many cases, the cost of the covering material accounts for about 20% or less of the manufacturing cost of the solar cell. Therefore, the reflection of sunlight on the liquid surface is 20
%, That is, the incident light on the solar cell is 20% or more.
%, The advantage of the present invention may be lost. When the specific gravity of the liquid is smaller than 1,
The upper surface of the liquid is always in direct contact with the atmosphere, and when the specific gravity of the liquid is greater than 1, the surface is in direct contact with the atmosphere when rainwater is not stored above this liquid. ing. Therefore, it is preferable that the refractive index of the liquid is smaller than 2.6 so that when sunlight enters the liquid from the atmosphere, its reflection is about 20% or less.

By the way, when the specific gravity of the liquid is larger than 1, and the rainwater is stored on the liquid, the calculation is as follows.

Assuming that the refractive index of the liquid is preferably 2.6, the reflection when sunlight enters the water from the air is about 1.7%. Similarly, the reflection when the sunlight enters the liquid from the water is about 1.7%. Is about 11%, which is 12.7 in total.
%. Therefore, as the reflection from the upper surface of the liquid becomes larger when the light enters from the air to the liquid than when the light enters from the air to the water → the liquid, the sunlight enters the liquid from the atmosphere as described above. When incident, its reflection is 2
The preferred upper limit is a refractive index of 2.6 which is about 0% or less.

However, since the refractive index of the solar cell surface varies depending on the type of solar cell used, reflection on the surface of the solar cell is not considered in the above description. However, if the sunlight reflects 20% or more before reaching the solar cell surface, a sufficient effect according to the present invention may not be obtained. Therefore, the preferred refractive index of the liquid is mentioned.

Further, it is preferable to select a liquid having an optimum refractive index so that reflection from the liquid to the solar cell is reduced.

It is preferable to have a means for circulating the liquid.

If the liquid can be circulated, the liquid can be easily exchanged. For example, if the liquid deteriorates and the light transmittance decreases, the old liquid can be recovered by circulation and a new liquid can be injected.

In addition, when the liquid flows on the surface of the solar cell, small objects on the surface of the solar cell, such as leaves of trees, can be removed by the flow. Therefore, it is possible to exclude those that may block the sunlight, and to remove those that may deteriorate the power generation performance.

Furthermore, the flow of the liquid on the surface of the solar cell can prevent dirt from being deposited on the surface of the solar cell, and can remove elements that may deteriorate the power generation performance.

In addition, the cooling effect of the solar cell described above can be more expected. The liquid is circulated,
It can be expected to be cooled by passing through places that are cooler than solar cells. More heat is radiated from the solar cell to the cooled liquid, and the solar cell can be expected to be cooled more. Therefore, better power generation performance can be expected.

Further, it is preferable to have a means for filtering suspended matter in the liquid. Thereby, even if there is an object that may block sunlight in the liquid, it can be removed by filtering the liquid. Therefore, the concern that the power generation performance of the solar cell is reduced can be eliminated.

Preferably, a mesh member is provided in the liquid, and a solar cell is mounted on the mesh member. This allows the solar cell to be installed without contacting the bottom surface of a container or the like that stores the liquid. As a result, even if the material on the liquid side surface of the bottom surface of the solar cell has high conductivity, the power generation performance of the solar cell can be improved by manufacturing this net-like member from an insulator or a material having high electric resistance. It has no effect.

Further, the net-like member does not obstruct the movement of the liquid on the light receiving surface side and the non-light receiving surface side of the solar cell. When rain is collected at the bottom of the means for storing the liquid as in an embodiment described later, it is desirable that the movement of the liquid on the light receiving surface side and the non-light receiving surface side of the solar cell is not interrupted. Further, by moving the liquid on the light receiving surface side and the non-light receiving surface side of the solar cell, cooling of the solar cell can be expected to be performed more efficiently.

It is also preferable that the solar cell be installed in the liquid at an angle. Thus, among the floating substances and the like in the liquid, those that are to be deposited on the solar cell surface are:
It can be expected to slide down the surface of the solar cell, reducing the possibility of deposits that may block sunlight, and reducing the concern of lowering the power generation performance of the solar cell. it can. In particular, when the solar cell is tilted to the south, a larger amount of power generation can be expected than when the solar cell is installed horizontally.

It is also preferable that a means for reflecting and condensing sunlight on the solar cell be submerged in the liquid, or that the liquid be stored in means for reflecting and condensing sunlight on the solar cell. As a result, the sunlight can be effectively condensed to the solar cell, so that the amount of power generation per unit area of the solar cell increases, and it can be expected that the cost-per-generation amount is excellent.

Further, the means for reflecting and condensing can be installed at low cost. The means for reflecting and condensing is usually a device having a large area and easily receiving wind force, and therefore, in order to manufacture it with sufficient wind resistance, it becomes a large-scale device and expensive. Often becomes. In this regard, when the reflection condensing means is immersed in the liquid, the apparatus is hardly affected by wind power, so that a simple and inexpensive apparatus can be provided as compared with a normal case. In addition, even when the liquid is stored in the reflection-condensing means, the liquid serves as a weight of the reflection-condensing means, so that the apparatus can be made simple in terms of wind resistance and inexpensive. Can be something.

Further, as the liquid, it is preferable to use any one of fluororesin oil, silicone oil, mineral oil and ester oil. Many of these have properties suitable for the present invention such as hydrophobicity, chemical stability, weather resistance, and non-volatility, and do not adversely affect the solar cell. Since various products are distributed in the market according to various uses, there is a high possibility that optimal products can be obtained from many candidates at low cost.

On the other hand, the present invention is characterized in that water is stored such that the upper surface is in direct contact with the atmosphere, and a water-resistant solar cell is submerged in the water.

In the case of using a solar cell having water resistance that does not cause a decrease in power generation performance even if it is immersed in water for a long period of time, the following method can be adopted by adopting an installation method of immersing this solar cell in water. There are such advantages.

First, as for the points which are not specified, such as the necessity of a fixing member and a supporting member, the same operation as the above-described invention submerged in a liquid having translucency and hydrophobicity can be obtained.

In addition, by using ordinary water as a liquid that plays a role of covering and protecting a solar cell, it can be obtained at very low cost. When using rainwater and groundwater, the water itself is free. Thereby, the installation cost of the solar cell is greatly reduced.

Here, in a special case where the positive electrode side part and the negative electrode side part of the solar cell are very close to each other with a large potential difference, a current flows due to the electric resistance of water and the power generation performance is reduced. It is as described above that there is a concern that this will happen.

However, such a case should be considered very rare. Therefore, in such a case, it is conceivable to perform a treatment for improving the insulating property only in a part of the solar cell where there is a concern, for example, by attaching an insulating film. With such a measure, the cost increase is small, and does not impair the object of the present invention.

The solar cell preferably has a light-transmitting resin coating material on the outermost surface layer on the light-receiving side of the solar cell element. Thus, for example, even a solar cell that does not have sufficient water resistance on the light receiving surface side can be immersed in water by using a resin coating material that is impermeable to water.

This resin coating material is assumed to be formed in a thin film, and is different from a normal coating material capable of sufficiently covering and protecting a solar cell. Such an increase in material costs would detract from the purpose of the present invention.

In addition, the advantage of using the resin coating material can prevent the possibility of damaging the light receiving surface of the solar cell element before the solar cell element is submerged in water. In particular, there is a possibility that the surface of the light receiving surface may be damaged by rubbing during transportation or installation. This can result in significant performance degradation for thin-film solar cells, such as amorphous silicon solar cells.

However, by providing a resin coating material on the outermost surface on the light receiving surface side of the solar cell element, damage due to rubbing or the like can be prevented.

In the present invention, a water-resistant solar cell is submerged in water. In the present invention, a means for circulating water, a means for filtering suspended matter in water, and a mesh member for mounting the solar cell are used. Is to install the solar cell at an angle in the water, submerge the means for reflecting and condensing sunlight into the solar cell in the water, or place water in the means for reflecting and condensing sunlight to the solar cell. It is preferable to have saved. The operation is the same as described above.

A power generation system having a solar cell installed by the above-described solar cell installation method and a power converter connected to the solar cell has a much lower initial installation cost than a conventional power generation system. You can expect it to be cheaper.

[0065]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a state where a solar cell is installed according to an embodiment of the present invention.

The solar cell 1 of this embodiment is mounted on a net 3 made of resin fibers. The area around these is filled with silicone oil 2, and water 4 is stored in the lower layer. These liquids are stored in a resin container 5 provided underground. A drain pipe 6 is provided at a lower portion of the container 5, and a circulation pipe 7 is provided at an upper portion.

Here, the solar cell 1 of this embodiment is one in which a semiconductor layer of amorphous silicon is formed on a stainless steel substrate. This will be described with reference to FIGS. FIG. 2 is a plan view of one solar cell of this example, and FIG.
It is the figure which represented the cut surface in A 'typically.

Referring to FIG. 3, a lower electrode layer 10, a semiconductor layer 11, and a transparent electrode layer 12 are sequentially laminated on a stainless steel substrate 9 to produce the same. Further, a current collecting electrode 13 for efficiently collecting generated power is formed on the transparent electrode layer 12. Then, the electric power collected by the current collecting electrode 13 is further led to two copper foils 14 provided on the sides of the solar cell to serve as electric output terminals. Finally, an acrylic resin coating material (not shown) is formed on the surface to a thickness of 25 μm. This coating material is provided to prevent the surface from being rubbed and damaged when the solar cell is handled during transportation or installation.

Since only the coating material is used as the coating material, in this embodiment, the cost required for providing the coating material can be reduced.

In this embodiment, zinc oxide is used as the lower electrode layer. It has been experimentally confirmed that when the solar cell element is immersed in water for a long time, the solar cell element is separated from the lower electrode layer from the stainless steel substrate side. The acrylic resin coating material also plays a role of waterproofing the solar cell element which cannot be said to have sufficient water resistance.

As described above, the cost can be reduced because no covering material for covering and protecting the solar cell is provided.

Here, in the case of this example, the light receiving surface side, which is the upper side in FIG. 3, is configured to be a positive electrode, so that the electrical output terminal of the copper foil 14 is a positive electrode and the stainless steel substrate is a negative electrode. .

A desired voltage is obtained by connecting a plurality of such solar cells in series and parallel. For example, by connecting a portion where the copper foil 14 extends outside the solar cell to a stainless steel substrate of an adjacent solar cell, the connection can be made in series.

As the silicone oil 2 of this example, dimethyl silicone oil is used. The dimethyl silicone oil of this example has translucency and hydrophobicity, as well as insulating properties and non-volatility, and has a specific gravity of less than 1. It is colorless and transparent.
At a wavelength of 2 μm, it has a sufficient transmittance of 80% or more. In addition, it has a methyl group, which is one of the alkyl groups, and has hydrophobicity that does not easily bind to water molecules. Further, regarding the insulating properties, the volume resistivity is 2.3.
× 10 ¹⁴ Ω · cm, and the above 1 × 10 ⁹ Ω · cm
It has a much larger electrical resistance. In addition, the refractive index is about 1.40.

The silicone oil of the present example having the above properties has a specific gravity smaller than 1 and is therefore stably stored in a layer above water 4. Furthermore, since the flash point is about 300 ° C., there is no fear of easily burning.

The solar cell 1 has a higher specific gravity than the silicone oil 2 and the water 4 and sinks. Therefore, the solar cell 1 is placed on the net 3 supported on the wall of the container 5. As described above, the net 3 is made of resin fibers and has insulating properties. Therefore, even if a plurality of the solar cells 1 are mounted, the potential of each stainless steel substrate does not short-circuit.

Here, since the silicone oil of the present example has a high insulating property, there is no fear that a current flows even between the solar cells arranged close to each other. In this example, it is assumed that the solar cells are connected in series so as to have a potential of about 250 V in the power generation operation state. With such a potential difference, if there is a device in which the positive electrode side part and the negative electrode side part do not come into contact, several mm
With a sufficient distance, there is no fear that a current flows between the positive electrode side portion and the negative electrode side portion to lower the power generation performance even when the devices are arranged close to each other.

Here, the circulation pipe 7 is connected to a circulation device (not shown), and the silicone oil 2 is always circulated in a very slow flow. A device for filtering small suspended matter such as dust contained in the silicone oil 2 is provided in a part of the circulation device.

With such a configuration, it is considered that dirt or the like hardly adheres to the light-receiving surface side surface of the solar cell 1, and it is possible to maintain good conditions for the solar cell to receive light.

Further, it is possible to change the silicone oil 2 sequentially. The silicone oil of this example is hardly deteriorated, and it is unlikely that a replacement event such as a decrease in light transmittance will occur easily. However, if it is desired to replace the silicone oil for some reason, it can be easily performed. Further, replacement of the solar cell can be very easily performed. Replace the solar cell when the power generation performance has deteriorated after months of use, or because of the technological innovation, a very high performance solar cell has been manufactured. It is possible. In this case, since the solar cell of this example has no covering material, only the solar cell needs to be replaced. The silicone oil 2 serving to protect the solar cell can be used as it is.

From the viewpoint of disposal, it is not necessary to separate the solar cell from the covering material and separate the solar cell and the covering material. This is a very useful method of installing a solar cell.

Next, a brief description will be given of a case in which a solar cell is normally installed and it rains. In the case of this example, since no member is provided on the upper side of the silicone oil 2, the rainwater directly falls on the silicone oil 2. This rainwater does not mix with the silicone oil 2 and has a higher specific gravity than the silicone oil 2, so that it mixes with the lower layer water 4. Thus, the solar cell can always be protected by the silicone oil 2 as desired.

If the rainwater continues to fall in this way, the level of the water 4 rises. Normally, the liquid level 8 in the drain pipe 6 is as shown in FIG.
It is in the position shown. This is at a position where the amount of water and silicone oil in the container 5 is balanced. When the liquid level 8 rises from there, it goes over the drainage position of the drainage pipe 6,
It flows out to the outside. Therefore, the inside of the container always maintains the state of the liquid level as shown in FIG.

As described above, the silicone oil 2 of this example
It can be seen that the upper surface is always in direct contact with the atmosphere. At this time, the reflection of sunlight on the upper surface of the silicone oil 2 is 1.40 because the refractive index of the silicone oil 2 is 1.40, which is considerably smaller than the above 2.6.
The reflectance is 2.8%, which is a small value.

In FIG. 1, the bottom of the container 5 is substantially horizontal. However, even if the bottom surface cannot be formed horizontally, the interface between the silicone oil 2 and the water 4 is always horizontal. In other words, even when the container 5 cannot be installed horizontally, the presence of water in the lower layer makes it possible to pour the silicone oil into the same configuration as when pouring the container with a horizontal bottom. As described above, in this example, storing water in the lower layer has the advantage that it is not necessary to use a large amount of silicone oil to sink the solar cell.

As described above, in this example, a solar cell with a very small amount of coating material and a solar cell in which a liquid in place of the coating material can be exchanged are realized. And there is no fixing member and support member for installing and fixing the solar cell, and the work is not required.

Here, the several solar cells described above are electrically connected in series to form a solar cell array that outputs a desired voltage. Outputs from the positive and negative electrodes of these groups of solar cell arrays are connected to a power conversion device that converts DC power to AC power via a connection box having a disconnector, and are distributed by a power company. It is a power generation system capable of reverse power flow connected to electric wires.

In this example, as described above, since the solar cell and the liquid surrounding the solar cell can be easily exchanged, it can be said that the power generation system can maintain the optimum power generation environment.

Further, as described above, since the solar cell and its installation cost are reduced, the cost of the initial installation of this power generation system is lower than that of the conventional one.

Next, each element used in the present invention will be described.

[Solar Cell] With regard to the solar cell according to the present invention, the photovoltaic element used can be a photovoltaic element as described in the following section, and the configuration is not particularly limited.

[0093] Since the object of the present invention is to reduce the amount of the coating material, it is preferable that the coating material is not used as much as possible. However, a small amount of coating material may be used in consideration of protection during transportation and handling. Conceivable.

However, considering that it is submerged in the liquid for a long time, it is desirable to have the following properties. Larger specific gravities are preferred because they can be easily submerged in the liquid.
It is preferable that the photovoltaic element has such a structural strength that the light-receiving surface portion of the photovoltaic element can always be developed without losing the flow or pressure of the liquid.

In addition, in the invention using the installation method of submerging in water, the solar cell used in the invention is required to have sufficient water resistance. It is premised that the power generation performance does not decrease even in the long-term water.

A solar cell having sufficient water resistance may be a solar cell made of only a material that does not dissolve in water or cause a chemical reaction with water, and does not require a waterproof device. Alternatively, the solar cell may have sufficient water resistance by being devised for waterproofing.

The following can be considered as a device for waterproofing, for example.

By adhering a waterproof resin film to the solar cell, water can be prevented from entering the solar cell. What is necessary is just to waterproof a necessary part, such as a light-receiving surface side, a non-light-receiving surface side, the whole surface, or only a part.

Further, a resin coating may be applied.

Similarly, it is also preferable to provide a device for improving the insulation of the solar cell. For example, in the invention relating to an installation method of submerging in water or in a liquid having low insulation properties, for example, an insulating film is attached to a solar cell only where the positive side and the negative side are close to each other with a large potential difference. Is also conceivable. Alternatively, it is conceivable to insert and install insulating rubber between the positive electrode side portion and the negative electrode side portion of the proximity portion.

[Photovoltaic Element] The photovoltaic element used in the solar cell according to the present invention is not particularly limited. Examples of photovoltaic devices include, for example, crystalline silicon photovoltaic devices, polycrystalline silicon photovoltaic devices, amorphous silicon photovoltaic devices, copper indium selenide photovoltaic devices, compound semiconductor photovoltaic devices, and the like. Can be used.

However, considering the case where no covering material is used for the solar cell, it is preferable to use a material which does not deteriorate by reacting with a desired liquid to be used. For example, in an amorphous silicon photovoltaic element or the like, a material serving as a substrate on which a semiconductor layer is formed is preferably a material having stability, such as stainless steel.

[Covering Material] As described above, it is preferable that the covering material for the solar cell in the present invention is not used as much as possible. However, when a small amount of coating material is used for the purpose of waterproofing and surface protection during handling such as transportation and installation as described above, it is preferable to have the following properties.

It has a light-transmitting property, and the light-transmitting property hardly decreases due to deterioration. It has insulating properties and does not react with the liquid that sinks solar cells. It has flame retardancy and is waterproof.

As an example, it is conceivable to form a thin film of a coating material made of an acrylic resin, or to attach a resin film.

Furthermore, if so, it is conceivable to apply grease having a light transmitting property.

[Liquid for submerging solar cell] In the present invention, the liquid for submerging a solar cell having no water resistance is:
The material is required to have translucency and hydrophobicity, and is preferably inexpensive, but the material is not particularly limited.

As to the light transmitting property, as described above, a material that can transmit 80% or more of sunlight at a wavelength of 0.4 μm to 1.2 μm is preferable.

As described above, as to the hydrophobicity, it is preferable that the structural molecule has a hydrophobic group so that a bond between the molecule and a water molecule is hardly formed. The hydrophobic group is preferably an alkyl group or a phenyl group.

The specific gravity is preferably not very close to 1. If the value is too close to 1, there is a possibility that it will take time before the water is separated and stored, and therefore, it is not preferable. Therefore, if the value is different from 1, the structures for storing the liquids are different from each other.

However, when the specific gravity is larger than 1, 1
The structure for storing the liquid is simpler than when the
It may be preferable because a simple device may be sufficient.

Regarding the insulating properties, the volume resistivity was 1 × 10
^{When the} resistance is about ⁹ Ω · cm or more, the degree of freedom in arranging the solar cells is increased as described above, which is preferable.

As described above, the refractive index is 2.6.
A smaller one is preferred. Regarding the viscosity, it may be preferable to lower the viscosity in order to reduce the load on the circulating device in consideration of circulation.

However, conversely, when used in a configuration that does not circulate, it may be considered that higher viscosity is preferable. A large resistance acts on an object traveling in a liquid having a high viscosity.
For example, even if a little large sand particles are rolled up by a strong wind and fall toward the solar cell surface, if the viscosity of the liquid surrounding the solar cell is high, the large resistance increases the impact force of the sand particles. We can expect that it decreases.

Further, since the liquid is non-volatile, there is no large change in the liquid amount, and it is easy to manage and is preferable.

Further, since the flash point is high, there is no fear of occurrence of a fire or the like, which is preferable.

For example, fluorine resin oil, silicone oil, mineral oil, ester oil and the like can be mentioned.

In particular, silicone oil is relatively inexpensive,
It is preferable because it has many of the properties required in the present invention. Therefore, more specific examples include dimethyl silicone oil, polydimethyl siloxane diol, methyl hydrogen silicone oil, methyl phenyl silicone oil and the like.

[Means for Storing Liquid] In the present invention, the means for storing the liquid for submerging the solar cell is not necessarily a container as long as it has the function of not leaking the liquid.

For example, a means for storing liquid may be formed by digging a hole in the ground and making a wall with concrete or the like.

Further, it is conceivable that a device for circulating the liquid, a water supply device, a drainage device and the like are additionally provided.

In addition, when the solar cell is placed on the bottom surface of the means for storing the liquid, it is preferable that the bottom surface portion is made of an insulating material. Even when the back surface of the solar cell has conductivity, there is no fear that the back surfaces of the plurality of solar cells are short-circuited.

[0123]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for installing a solar cell according to the present invention will be described based on examples. The solar cell module according to the present invention is not limited to these examples.

(Example 1) This example is characterized in that a methylphenyl silicone oil 15, which is a silicone oil having a specific gravity larger than 1, was used.

The other points that are not specified are the same as those of the above-described embodiment of the present invention.

As shown in FIG. 4, this embodiment is installed on the roof of a building, and reference numeral 17 denotes a concrete surface on the roof. Although the concrete surface on the roof may be slightly inclined for drainage, it is almost horizontal, so that the resin container 16 is directly placed thereon.

In the container 16, methylphenyl silicone oil 15 is stored, and the solar cell 1 is submerged at the bottom of the container.

The solar cell 1 of this example is the same as the embodiment of the present invention except that the above-mentioned acrylic resin coating material is not coated. When transporting or installing solar cells,
Although care must be taken to prevent damage due to rubbing or the like, the material cost of the coating material can be reduced.

Here, the reason why a coating material is used in the embodiment of the invention and not used in this example will be described below.

This is because, in this example, there are conditions under which the solar cell can be used even if the water resistance is inferior to the example shown in the embodiment of the invention.

First, the methylphenyl silicone oil of this example has a very low water absorption. Therefore, the possibility that the solar cell wrapped in methylphenyl silicone oil comes into contact with water is extremely low. The dimethyl silicone oil has a hydrophobic group and exhibits high hydrophobicity, but has a slightly higher water absorption than the methylphenyl silicone oil of the present example, so that the possibility that the solar cell comes into contact with water is small. Become higher.

Second, rainwater accumulates in the upper layer in this example, as will be described later. In the case of the embodiment of the present invention, since it is configured to accumulate in the lower layer, there is a high possibility that the rainwater falling on the liquid surface will touch the solar cell before reaching the lower layer. In consideration of a case where rain has continued to fall for a long time, it is preferable not to use a solar cell which is considered to have poor water resistance.

On the other hand, in this embodiment, since the rainwater is stored above the liquid, it is considered that the rainwater that has fallen is stored directly above without contacting the solar cell.

For the above reasons, even if the same solar cell element is used, in the embodiment of the present invention, the coating is waterproofed and the water resistance is improved, but in this embodiment, the coating is omitted. .

In this example, a brief description will be given of a case in which a solar cell is normally installed and it rains. In the case of this example, since no member is provided above the silicone oil 15,
Rain water falls directly onto the silicone oil 15. This rainwater is not mixed with the silicone oil 15 and has a specific gravity lower than that of the silicone oil 15, so that the rainwater accumulates in the upper layer of the silicone oil 15. Thus, the solar cell can always be protected by the silicone oil 15 as desired.

If the rainwater continues to fall in this way, the water will accumulate more and more in the upper layer of the silicone oil 15 and only the water overflows from the container and is discharged. The water remaining without overflowing from the container evaporates gradually and disappears.

(Embodiment 2) This embodiment is characterized in that a silicon rubber sheet is laid and liquid is stored thereon, instead of using a container as a means for storing liquid.

Other points that are not specified are the same as in the first embodiment.

This embodiment will be described with reference to FIG. FIG.
FIG. 3 is a cross-sectional view showing a state where a solar cell is installed in the present embodiment. First, the bank 19 is made by raising the soil so that the liquid does not flow. Then, a silicone rubber sheet 18 is laid. Next, concrete is poured in and hardened so that the upper surface is horizontal. This concrete serves as a weight and forms a horizontal bottom surface for pouring liquid. Note that a waterproof coating (not shown) is provided on the upper surface of the concrete.

The same solar cell as in Example 1 is used. As the liquid surrounding the solar cell, methylphenyl silicone oil 15 having a specific gravity of more than 1 is used as in the first embodiment.

With the installation method described above,
In this embodiment, a large container is not used. When a large container is used, it is necessary to transport the container from the production site, which requires transportation costs. However, in this example, since a substitute for the container is produced at the installation site, the cost can be reduced.

Further, although the work of raising the soil is necessary, the leveling work for forming a horizontal and smooth surface can be greatly simplified, so that the cost can be reduced also in this respect.

(Embodiment 3) This embodiment is characterized in that a solar cell having water resistance is used and immersed in water.

This embodiment will be described with reference to FIG. FIG.
FIG. 3 is a cross-sectional view showing a state where a solar cell is installed in the present embodiment. The solar cell 21 according to the present embodiment is similar to the solar cell according to the first embodiment.
A solar cell element not provided with a coating material similar to that described above is used. In the present example, a fluororesin adhesive sheet was attached to the front and back of the solar cell element, and the solar cell element was sandwiched between the solar cell elements to completely waterproof the solar cell element. Thereby, a solar cell having sufficient water resistance can be obtained. This fluororesin pressure-sensitive adhesive sheet is obtained by applying a silicon pressure-sensitive adhesive to a 50 μm-thick fluororesin sheet, and has excellent weather resistance.

The solar cell 21 is used for the water 22 in the container 26.
Sink in This container 26 is placed on the rooftop concrete surface 17 as in the first embodiment.

Reference numeral 23 denotes a drain pipe, and 24 denotes a water supply pipe. Usually, the water level is maintained as shown in FIG. When it rains,
When the accumulated rainwater reaches the water level of the drain pipe 23, it flows naturally.

Here, in the present embodiment, there is a mechanism for protecting the solar cell by raising the water level in a strong wind or the like. When it is known from the weather forecast or the like that a strong wind such as a typhoon blows, the drain port of the drain pipe 23 is closed with the stopper 25. Then, water is injected from the water supply pipe 24 to reach a water level near the upper end of the container 26. As a result, a larger amount of water than usual is stored on the upper side of the solar cell. In this state, the top of the water may swell in strong winds, but the solar cells sinking at the bottom are not likely to be affected by the wind. In addition, even if pebbles large enough to be soared by the wind are heading for the solar cell, they will lose energy while traveling in a large amount of water and will not hit the pebble at a speed enough to damage the solar cell it can. When the weather is fine, the plug 25 is opened to generate power at the normal water level.

In this embodiment, no device for circulating water is provided. However, at the bottom of the container 26,
There is a drain port (not shown), and by draining and supplying water as necessary, it is possible to maintain clean water that does not affect the power generation performance. At that time, it can be expected that dirt and suspended matters are also washed away.

Here, despite the use of the same solar cell element, the reason why the pressure-sensitive adhesive sheet material was attached to the front and back as a means of improving the water resistance in the present embodiment is as follows.

This is because the method of sandwiching between the adhesive sheet materials can expect very high waterproofness. On the other hand, waterproofing with a coating material is considered to have a poor reliability in waterproofness because a method of sandwiching with a pressure-sensitive adhesive sheet material is considered to be more reliable because application failure of the coating material is considered.

However, even in the case of a coating material, it is possible to have a high degree of reliability in waterproofness by sufficiently considering the material and application method, and to adopt the installation method of submerging in water as in this example. Can be.

In other words, here, the installation method of this example is that only the solar cell which has been subjected to excellent waterproofing and has high water resistance and high reliability is submerged in water even if similar solar cell elements are used. It can be used to indicate that.

(Embodiment 4) The present embodiment is characterized in that a wall is provided on an inclined surface, a silicon rubber sheet is laid, water is stored, and a water-resistant solar cell is sunk there along the inclined surface. And

Other points that are not specified are described in Example 3.
Is the same as

This will be described below with reference to FIG. By simply performing a simple leveling operation on the inclined surface 27 facing the south direction by removing large stones and the like, the wall 28 is provided on three sides and the silicon rubber sheet 18 is laid so that water can be stored. . Further, the support member 29 is placed to support the lower end so that the solar cell 21 does not slide down. This is only that the lower end of the solar cell is abutted against the support member 29 which remains at a desired position by its own weight.

Here, by having a drain port and a water supply port (not shown), a desired water level can be maintained. For example, the drain outlet is provided on the upper end side and the lower end side of the wall 28. The role of the drain port on the upper end side is to keep draining the rainwater at a constant level when rain continues to fall. The drain port on the lower end side is normally closed, and is opened when the stored water is to be drained. This makes it possible to easily perform operations such as checking the solar cell 21 and wiping off dirt. At the time of this drainage, it is expected that the substance adhering to the surface of the solar cell 21 is removed by the flow of water, and there is a possibility that the work of wiping off the dirt as described above is unnecessary.

In the installation method of the present embodiment described above, since the solar cell 21 is installed at an angle, it can be expected that dust or the like on the surface of the solar cell will slide down.

Further, since the solar cell is inclined in the south direction, the solar cell is horizontally installed as in the above-described embodiment.
More power generation can be expected.

Here, in this embodiment, the solar cells are installed in an inclined manner by using inclined surfaces, but it is also conceivable to use a very simple mount.

[0160] For example, on a horizontal land, a pool-like object is made by laying a silicon rubber sheet around the walls on the four sides in the same manner as described above. By installing a very simple base in the solar cell, the solar cell is installed to be inclined in the south direction. In this case, there is no need to consider wind resistance and the solar cell becomes lighter due to the buoyancy of water. Therefore, the required structural strength is very small as compared with a normal mount. Therefore, a very simple base can be used. Furthermore, it is considered that a member that can support the solar cell while being inclined is not limited to the concept of the gantry, so that the installation cost can be extremely low.

Embodiment 5 This embodiment is characterized in that a container capable of reflecting and condensing sunlight is used as a means for storing water.

Other points not specified are described in Example 3.
Is the same as

This will be described below with reference to FIG. A container 30 capable of reflecting and condensing sunlight is buried in the ground by depositing aluminum on the surface, and water is stored in the container. The solar cell 21 is supported and fixed on the upper side of the water, at the position where light is collected. This solar cell 21 has a back reinforcing plate 31. The rope 32 fixed to the back reinforcing plate 31 balances the own weight of the solar cell 21 and supports and fixes the solar cell.

Also in this embodiment, the water level is adjusted to a desired position by providing a drain port and a water supply port (not shown).

With the configuration as in this embodiment,
Since the incident light to the solar cell is collected, the amount of power generation per unit area of the solar cell is larger than that in the above-described embodiment. As a result, the amount of use of the solar cell can be reduced, and the amount of power generation obtained with respect to the total cost of the solar cell system is considered to be advantageous.

Further, in this embodiment, since the solar cell is only supported and fixed by the rope, a frame is not required, which is advantageous from the viewpoint of installation cost.

In this embodiment, the container capable of storing water has the function of reflecting and condensing sunlight, but the function of storing water and the function of reflecting and condensing sunlight are performed. It may be implemented by separate means. For example, as in the fourth embodiment, it is conceivable to make a pool-like object and to sink a reflecting mirror for reflecting and condensing sunlight together with the solar cell in the pool.

Since the reflector submerged in water is hardly affected by wind power, there is no need to have sufficient structural strength, and there is a possibility that the reflector can be made simple and inexpensive.

[0169]

As described above, according to the present invention, a liquid or a liquid having transparency and hydrophobicity is stored, and the solar cell is immersed in the liquid or the water, whereby the following is achieved. Such effects can be obtained.

First, since the liquid or water can fulfill the function of the covering material provided in the solar cell, the covering material can be largely reduced, and the cost can be greatly reduced.

In addition, a fixing member and a supporting member for fixing the solar cell are not required, and the work of fixing the solar cell can be omitted. This makes it possible to construct a photovoltaic power generation system in which the initial installation cost of the solar cell is low.

Further, the liquid or water for sinking the solar cell can be easily exchanged. Since it is not integrally formed with the solar cell like the covering material, it can be easily replaced even if, for example, the liquid or water deteriorates and the light transmittance decreases. Thereby, the state in which the solar cell can always receive sufficient light can be maintained.

Further, from the viewpoint of the disposal of the solar cell,
It can be said that separation is easy and excellent. Solar cells and liquids
By being discarded separately according to each life, there is no waste to be discarded with the life left, and it is possible to separate and discard in consideration of recycling.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a method for installing a solar cell according to the present invention.

FIG. 2 is a plan view of a solar cell according to the present invention.

FIG. 3 is a schematic cross-sectional view taken along a cutting line AA ′ in FIG.

FIG. 4 shows a first embodiment of a method for installing a solar cell according to the present invention.
FIG.

FIG. 5 is a second embodiment of a method for installing a solar cell according to the present invention.
FIG.

FIG. 6 shows a third embodiment of a method for installing a solar cell according to the present invention.
FIG.

FIG. 7 shows a fourth embodiment of a method for installing a solar cell according to the present invention.
FIG.

FIG. 8 shows a fifth embodiment of a method for installing a solar cell according to the present invention.
FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 21 Solar cell 2, 15 Silicone oil 3 Netting 4, 22 Water 5, 16, 26 Container 6, 23 Drain pipe 7 Circulation pipe 8 Liquid surface 9 Stainless steel substrate 10 Lower electrode layer 11 Semiconductor layer 12 Transparent electrode layer 13 Current collecting electrode 14 copper foil 17 roof top surface 18 silicon rubber sheet 19 embankment 20 concrete 24 water supply pipe 25 plug 27 inclined surface 28 wall 29 support member 30 container having a surface capable of reflecting and condensing sunlight 31 back reinforcing plate 32 rope

Continuation of the front page (72) Inventor Ayako Komori 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masaaki Matsushita 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo Canon Inc. (72) Inventor Takaaki Mukai 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Kimitoshi Fukae 3-30-2 Shimomaruko 3-chome, Ota-ku, Tokyo F-term (reference) 5F051 AA05 BA11 BA18 FA02 GA02 HA20 JA09 JA14 JA16 JA20 KA07

Claims (21)

[Claims] 1. A liquid having translucency and hydrophobicity is stored such that the upper surface thereof is in direct contact with the atmosphere.
A method for installing a solar cell, wherein the solar cell is submerged in the liquid. 2. The solar cell according to claim 1, wherein the liquid has a translucency capable of transmitting 80% or more of sunlight at a wavelength of 0.4 μm to 1.2 μm. Installation method. 3. The liquid according to claim 1, wherein the liquid has a hydrophobic group that has a hydrophobic group in a structural molecule thereof, so that the liquid hardly forms a bond with a water molecule.
Installation method of the solar cell described in. 4. The method according to claim 3, wherein the hydrophobic group is an alkyl group or a phenyl group. 5. The method according to claim 1, wherein the liquid has a specific gravity smaller than 1. 6. The method for installing a solar cell according to claim 1, wherein the liquid has a specific gravity greater than 1 and smaller than a specific gravity of the solar cell. 7. The method according to claim 1, wherein a refractive index of the liquid is smaller than 2.6. 8. The method according to claim 1, further comprising means for circulating the liquid. 9. The method for installing a solar cell according to claim 8, further comprising means for filtering suspended matter in the liquid. 10. A net-like member provided in the liquid, and a solar cell is mounted on the net-like member.
10. The method for installing a solar cell according to any one of claims 9 to 9. 11. The method for installing a solar cell according to claim 1, wherein said solar cell is installed in said liquid at an angle. 12. The liquid crystal according to claim 1, wherein a means for reflecting and condensing sunlight on the solar cell is submerged in the liquid, or the liquid is stored in means for reflecting and condensing sunlight on the solar cell. A method for installing a solar cell according to any one of claims 1 to 11. 13. The method according to claim 1, wherein the liquid is any one of a fluororesin oil, a silicone oil, a mineral oil, and an ester oil. 14. A method for installing a solar cell, comprising storing water so that an upper surface thereof is in direct contact with the atmosphere, and submerging a water-resistant solar cell into the water. 15. The method for installing a solar cell according to claim 14, wherein the solar cell has a light-transmitting resin coating material on a light-receiving surface side outermost layer. 16. The method according to claim 14, further comprising means for circulating the water. 17. The method according to claim 16, further comprising means for filtering the suspended matter in the water. 18. A net-like member provided in the water, and a solar cell is mounted on the net-like member.
18. The method for installing a solar cell according to any one of items 17 to 17. 19. The method for installing a solar cell according to claim 14, wherein the solar cell is installed inclined in the water. 20. A method in which means for reflecting and condensing sunlight on a solar cell is submerged in the water, or the water is stored in means for reflecting and condensing sunlight on the solar cell. A method for installing a solar cell according to claim 14. 21. A power generation system, comprising: a solar cell installed by the method for installing a solar cell according to claim 1; and a power converter connected to the solar cell.