JPH0139228B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a plurality of photocells that are electrically interconnected and connected to an output conductor such that at least one
The present invention relates to a method of making a panel of solar photocells forming a battery embedded in at least one layer of plastic material sandwiched between two rigid sheets, one of which is transparent.

Solar photocells are primarily used to supply power to equipment such as lighthouses, unmanned electrical signal stations on land and at sea, and television relay stations in mountainous areas.

Typically, electrically interconnected solar photocells are supplied as batteries arranged in a panel configuration for ease of installation and use. It is very important that the photocell (e.g. silicon semiconductor) surface does not change its properties even when exposed to weather conditions that require that the photocell be protected from the outside air so that the surface remains stable. . It is therefore necessary to keep the panel airtight, especially with respect to air and moisture, otherwise the efficiency of the photocell will be reduced, and indeed the life of the photocell depends on its protection.

On the other hand, in order to obtain a sufficiently high electrical output,
The solar panel must be of sufficient size. Therefore, the cost of panel fabrication increases depending on the price of the semiconductors used, the price of the mechanical structures, and the labor time invested in the panel fabrication and thus included in the fabrication cost.

Various types of solar panels have already appeared on the market. When using two sheets of polyvinyl butyral resin, the most widely used thermoplastic resin for making laminated panels, it has proven very difficult to produce panels that are free of bubbles or other defects. A panel is made by placing interconnected photocells between two glass sheets, filling the space between the glass sheets and the photocells with syrupy transparent resin, and curing the resin sufficiently through a polymerization reaction to form a battery. That's because of that reason. Panels made in this manner will have defects in uniformity or air bubbles that become trapped during resin injection. Therefore, this panel is considered unusable. This manufacturing method requires great care and time, which increases the cost per watt of output of the resulting device.

According to the present invention, a plurality of photocells electrically interconnected and connected to output conductors are formed of two rigid sheets, at least one of which is transparent, so that light can reach the light-receiving surface of the photocells. A method of fabricating a panel of solar photocells forming a battery embedded in at least one layer of plastic material sandwiched between the photocells, the fabrication method comprising: Then, the electrical conductor part is covered with a layer of powdered thermoplastic resin material, the photocell covered as described above and the conductor part are sandwiched between two hard sheets, and the resin material is melted at that location. A method of making a solar photocell panel is provided, the method comprising bonding a resin material to a photocell and a rigid sheet.

This will result in a panel free of air bubbles and other foreign matter. The panels may also be airtight if covered with a sufficiently wide thermoplastic strip or by forming a peripheral seam with another material.

To melt the powder, a sandwich structure consisting of two rigid sheets sandwiching a network structure of photocells covered with granulated thermoplastic resin is inserted into an elastic bag, and the inside of the sandwich structure is inserted into an elastic bag. Create a vacuum inside the bag to expel any trapped air.
At the same time, a pressure greater than atmospheric pressure is applied from around the bag in the autoclave, and then the temperature and pressure inside the autoclave are gradually increased to soften the thermoplastic resin powder. When melted, it becomes plasticized, so it is slowly cooled. , restore the pressure inside the autoclave and release the vacuum.

The use of sintered preforms makes it possible to work with even greater precision, and in particular eliminates undesirable irregularities in layer thickness that occur when filling with thermoplastic resin powder. The unevenness, which causes cracking and breakage of the rigid sheet or deterioration of the network structure, can be eliminated.

Such a method involves feeding a thermoplastic resin powder into a preforming mold with a relief forming a recess to reproduce the pattern of a solar photocell, with the upper surface level, and this powder filling. The sintered preform is heated to a temperature at which the powder sinters, the sintered preform is removed from the mold, and placed on one of the rigid sheets with the recess facing upward, and the recess is placed in the recess. A network structure of connected photocells is inserted, this assembly is covered with a second rigid sheet, and the panel thus obtained is subjected to a heat treatment under vacuum to expel the air contained inside and prepare the panel. It consists of gluing the molded body to a rigid sheet.

The advantage of this method is that sintering does not change the thickness of the preform and therefore provides constant support.

A method of manufacturing a panel according to the present invention will be described below with reference to the accompanying drawings. In the accompanying drawings: FIG. 1 is a plan view of a photocell panel obtained by the method of one embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of the cut plane taken along the dashed line - in FIG. 1. FIG. 3 is a cross-sectional view of another panel made by one embodiment of the present invention, and FIG. 4 is a diagram showing the steps in making the panel by the method of the present invention. FIG. 5 is a vertical sectional view schematically showing the preforming operation of the product in the method of the present invention.

1 and 2, a panel 1 in its final form made by the method of the invention is shown. This panel is
It consists of interconnecting the photocell elements 2 with conductive strips 3, with at least two connecting strips 4 extending outside the panel.

The photocell 2 is in a layer 5 of transparent thermoplastic material. The layer is placed between two airtight rigid sheets 6 and 7. At least one of the two sheets (sheet 6) is made of a transparent material, such as glass, plastic material or transparent glass crystalline material.

The panel shown in FIG. 3 has a layer 5 bonded to the member forming layer 5 and said rigid sheet, respectively, and between two flexible thermoplastic sheets 8 and 9.
It is similar to the panels of FIGS. 1 and 2, except that it is sandwiched between the panels. These sheets 8 and 9 are layer 5
It is advantageous to make it from the same material.

The thermoplastic material of layer 5 is a synthetic resin such as plastic polyvinyl butyral. A resin of this type is described in French Patent No. 2401941.
Generally, the plastic materials used are esters of acids (insoluble in water) having multiple carboxylic acid groups or multiple hydroxyl groups. Among other plasticizers used are polyethylene glycol derivatives such as triethylene glycol di-(ethyl-2-butyrate), triethylene glycol dipelargonate, and diethyl adipinate, dibutoxyethyl adipinate and 1978 Included are alkyl or aryl adipates as well as dibutyl sebaccinate as described in French Patent Application No. 78 32,737 filed November 21st.

Plasticizers that can be used in polyvinyl butyral resins are not limited to those listed above. A person skilled in the art will be able to select the most suitable plasticizer from among the many known ones.

The photocell may be a phosphor such as monocrystalline or polycrystalline silicon, cadmium telluride, cadmium sulfide, polycrystalline or monocrystalline gallium arsenide, or indium. The output connection strip may be, for example, plated copper, silver, aluminum and alloys thereof or other electrically conductive metal compositions. Two pieces of 0.3mm
thick glass, polyvinyl butyrate resin as described in French Patent Publication No. 2401941;
The airtight panels are created using plasticizers and silicone photocells in the form of discs 0.3 mm thick and 57 mm in diameter. The photocell connection strip is plated copper.

Hereinafter, a method for manufacturing a photocell panel will be explained by way of example, but the following example does not particularly limit the present invention.

Example 1 (Reference Example) A powder mixture of a polyvinyl butyral resin and a plasticizer formed from triethylene glycol di-(ethyl-22-butyrate), consisting of 41 parts by weight of plasticizer per 100 parts by weight of the resin, was It was passed through a sieve and removed onto a sheet held horizontally. This mixture was previously prepared using a kneader-type planetary mixer at ambient temperature.

The apparent density of the mixture was 0.2 g/m ³ .
The thickness of the plastic resin layer provided on the glass was 5 mm. The interconnected photocells were placed on top of the plastic resin layer within the panel using a pneumatic lift system consisting of suction means for each photocell.

A new layer of the same plastic resin was then applied over the stacked layers. This layer was also made as uniform as possible and had a thickness of 5 mm. A 3 mm thick glass sheet was deposited on top of this new layer. As shown in FIG. 4, the sandwich structure thus obtained is then placed in an elastic bag 10, such as rubber, and a tube connected to a vacuum pump (not shown) for gas suction. The inside of the bag was evacuated via No. 11. This bag is placed inside the autoclave 12. After leaving the bag under vacuum for 30 minutes at ambient temperature, compressed air was pumped into the autoclave to create an overpressure of 2 bar on the outside of the bag. The vacuum inside the bag continued to be maintained. Then, the temperature inside the autoclave was gradually increased at a rate of 4°C/min. When the temperature reaches 100℃, reduce the excess pressure on the outside of the bag by 5℃.
Increased to 10 bar for min. The temperature was then raised to 140°C. After remaining at 10 bar and 140° C. for 30 minutes, the Sanderch structure assembly was cooled while maintaining the pressure. The pressure inside the autoclave was released, the vacuum was broken, and the panels were collected. When I looked through the light, I didn't see any bubbles in this solar panel.

Example 2 (Reference Example) The treatment method of Example 1 was followed, except that the content of the triethylene glycol di-(ethyl-2-butyrate) plasticizer was 20 parts by weight per 100 parts by weight of the resin. However, the maximum temperature reached within the autoclave was 150°C. The resulting panel was free of air bubbles and foreign matter.

Example 3 (Reference example) The treatment method of Example 1 was followed, but the plasticizer was added to the resin.
The amount of benzyl octyl adipinate was 34 parts by weight per 100 parts by weight. There were no air bubbles or foreign objects in the panel.

Example 4 (Reference example) Polyvinyl butyrate resin containing 41 parts by weight of triethylene glycol di-(ethyl-2-butyrate) per 100 parts by weight of the resin was placed on a heated glass sheet using the rolls of a shaping machine. Crimp and
It was made into a plastic sheet with a thickness of 0.5 mm. On top of this layered assembly, interconnected silicone photocells are placed in an apparatus similar to Example 1, and polyvinyl butyral resin and triethylene glycol di( Ethyl-2
- butyrate) The powder mixture with the plasticizer could be allowed to fall through the sieve from above on which the photocell was placed. A sheet of glass was deposited on top of the polyvinyl butyral resin layer. The mass was then placed in an elastic bag and treated as in Example 1 in an autoclave. When the resulting panel was viewed through light as in the previous example, no air bubbles or foreign matter were found.

Example 5 (Reference example) A transparent, rigid sheet is covered with a powder mixture layer of a thermoplastic material and a plasticizer, and interconnected photocells are placed on this, so that the surface of the cell is higher than the surface of the powder layer. I pushed it in until it sank to the bottom. next,
A second transparent, rigid sheet was deposited directly over the photocell without covering it with a new layer of thermoplastic material and plasticizer. The second sheet uses the sheet's own weight and low pressure applied from the outside to push the mountain of powder protruding between the photocells and flatten it to form a layer of a certain thickness. I worked like that. The assembly was then processed in an autoclave in the same manner as before to create panels.

Example 6 (Reference Example) Depending on the size of the photocell, it may be possible to surface the photocell with a sheet of plasticized thermoplastic resin in the process of Example 5 without first forcing the photocell into the powder layer. could be covered with a second transparent, rigid sheet applied thereon.

Example 7 (Reference Example) A panel was made that was more completely airtight than the panels made according to Examples 1 to 4. The panels were covered with a mold on all four sides, and a silicone resin known by Rhone Poulenc's trademark "RTV" was injected into the mold. In this example, the mold was made of polymethyl methacrylate.

Other additives were also included in the plastic polyvinyl butyral powder. Additives that may be included include stabilizers, UV degradation inhibitors, adhesion modifiers, and the like.

Example 8 (Reference example) In this example, di(ethyl)
A 0.5 mm thick layer of polyvinyl butyral plasticized with 41 parts by weight of (2-butyrate) triethylene glycol was provided on top of the first layer of glass. A photocell was deposited on top of this polyvinyl butyral layer. In the gap between the photocell and the layer to which it was attached, a layer of plasticized polyvinyl butyral powder was removed in the same manner as in the previous layer. On top of this powder layer, a new powder layer made of the same plastic polyvinyl butyral as the first layer and having the same thickness of 0.5 mm was provided. lastly,
A sheet of glass was placed on top of the second sheet. The panels thus produced in elastic bags were inserted into an autoclave and processed as described in Example 1.

After removing the panel from the autoclave and bag, no air bubbles or foreign matter were observed when light was shined through the solar panel.

Example 9 If it is desired to use a thinner than normal photocell, or if there is sufficient polarization between the top active surface of the photocell and the top rigid transparent sheet (and after the panel has been autoclaved). If it was desired to create a thin polyvinyl butyral layer, the following procedure was performed.

On top of the first rigid sheet (transparent or not) was applied a layer of polyvinyl butyral followed by an interconnected photocell 0.8 mm thick.
A cover was placed over each photocell that could be easily pulled off after being covered with polyvinyl butyral powder. If the system for pneumatically lifting the photocell described in Example 1 allows the removal of the polyvinyl butyral powder and allows it to be withdrawn without disturbing the layer, it may be used on top of the photocell during removal. do. An attempt was also made to arrange an approximately 1.5 mm thick aluminum disc-shaped cover on the top surface of each photocell, with the same area as the top surface of the photocell. Each disc includes a more or less vertical mandrel that has a height well beyond the height it would have after the polyvinyl butyral layer on the top surface of the photocell was applied. After applying the polyvinyl butyral layer, the assembled cover was pulled out using a mandrel in any conventional manner. After removing the powder between the photocell and the cover and withdrawing the cover, a new layer of polyvinyl butyral powder was applied over the photocell. A transparent rigid sheet, such as a glass sheet, was then placed over it. The panel thus produced was inserted into an elastic bag connected to a vacuum pump as in Example 1, placed in an autoclave, and subjected to airtight treatment under high temperature and pressure.

Pre-use of the cover made it possible to avoid exceeding the thickness of the polyvinyl butyral powder layer on the photocell. If there is an excess thickness, breakage or cracking may occur in a photocell covered with an excessive thickness of polyvinyl butyral powder relative to another photocell during processing by heat and pressure in an autoclave. There is a possibility that this may occur.

In the method according to the invention, a preformed sintered powder was used in order to avoid variations in the thickness of the thermoplastic resin powder layer. Referring to FIG. 5, preforming is carried out using a mold 15 in the form of an upwardly open flat dish. The mold is flat-bottomed and corresponds to the quantity of photocells in the network structure to be coated, and a rigid part (or element) 16 approximately equal to the contour and size of the photocell is placed on the bottom of the mold. It was either integrated or attached only during the molding process. The partition plate 17 of the mold is perpendicular to the bottom surface, ends at a sharp end 18 on the upper side, and the entire end is located in the same plane parallel to the bottom surface. The mold cavity was coated with a suitable anti-stick coating.

A method of making photocell panels by preforming is described in the examples below.

Example 10 A conveyor 19 such as a roller conveyor in which the mold 15 is placed horizontally with the cavity facing upward.
It is placed on top of the paper and placed in the remover 20 containing the thermoplastic resin powder. A benzyloxyadipinate-plasticized polyvinyl butyral resin consisting of 100 parts by weight of resin to 34 parts by weight of plasticizer was used in the ablation powder. Mold 0.4m/
1000 g/m ² of plastic powder was removed onto the mold by passing it under the remover at a speed of 10 min.

After the mold was overfilled with powder, it was conveyed to a station with a smooth shaping cylinder 21 that rotated regularly on a horizontal axis. The cylinder is adjusted to a height such that it is flush with the sharp end 18, so that as the mold passes under the cylinder, excess powder is removed and the top surface of the preform is leveled. . Furthermore, the ends of the preform are cleanly cut flush with the sharp edge 18 of the mold. Excess powder was collected by collector 22.

The mold filled with powder is then conveyed into a tunnel furnace 23 heated to a temperature of 50°C. When the mold was left in the furnace for 10 minutes, a sintered body of plastic polyvinyl butyral was obtained.

Upon exiting the furnace, the powder-sintered preform 24 was removed from the mold, creating a recess 25 in one surface capable of receiving a 0.3 mm thick photocell previously interconnected. The thickness of the preform was approximately 5 mm, and the depth of the recess was 1.5 mm.

The preform 24 is then placed on the lower rigid sheet.
was placed with the recess facing upward, and then the interconnected photocell network structure was inserted into the recess. The assembly was then covered with an approximately 5 mm thick layer of plastic polyvinyl butyral containing an equal amount of benzyl octyl adipinate. The upper rigid sheet was then placed over the aggregate and the resulting sandwich structure was treated in the same manner as in Example 1.

Example 11 Processed using the previous treatment method, but instead of 0.5 mm thick polyvinyl butyral, 2.5
A preformed body with a thickness of mm was obtained.

A photocell panel free of air bubbles and foreign matter was obtained.

Example 12 A photocell network structure is deposited on a first layer of plastic polyvinyl butyral supplied to the bottom of the mold cavity, and then covered with a second layer of plastic powder with a smooth surface as in Example 1. The mold was then sent into a tunnel furnace heated to 50°C and left there for 15 minutes. In this way, a sintered preform with a thickness of 10 mm was obtained, which covered the network structure of the photocell. The panel consists of 2 layers whose top sheet is a thin film with a thickness of 0.3 mm.
It was made by incorporating a preform between two glass sheets.

Example 13 The processing method of Example 10 was carried out, but polyvinyl butyral powder was preformed without being plasticized, and
It was held for 15 minutes in a tunnel furnace heated to . The obtained preform was assembled with the other elements of the solar panel as in the previous example.

Example 14 In the special case of using photocells of a shape other than circular, e.g. rectangular or crescent shaped with rounded edges, arranged in a substantially continuous configuration, flat preforms and photocells may be used. A network structure of interconnected photocells was placed between a preform having a recess formed around the assembly with a single perimeter.

Example 15 The procedure of Example 10 was carried out, with the exception that the sandwich structure was formed with a rigid plate of acrylic polymer instead of a glass sheet.

A pretreatment was applied to the polyvinyl butyral resin and to the surface of the acrylic plate in sandwich-like contact with it to achieve better adhesion. That is, first wash with detergent-containing water, rinse, dry, and then add anhydrous ethanol and an acrylic adhesive to a viscosity of 1000 centipoise (25 °C) to improve the adhesion of polyvinyl butyral to the acrylic plate. It's melting like that. Treatment was carried out by spraying or brushing a solution obtained from a 50:50 mixture with 1,2-dichloroethane. The treated surface was dried for 30 minutes at a temperature not exceeding 50°C.

During assembly of the sandwich structure, care was taken to contact the treated surface of each acrylic plate with the polyvinyl butyral resin;
A glass sheet prepared to a thickness of 6 mm was placed on the untreated surface of each plate. The sandwich structure was placed in a vacuum bag and solar panel fabrication was carried out as described in Example 10.

The prepared glass sheet can be easily separated from the final panel, with the aim of preventing as much distortion as possible during the passage of the sandwich structure through the autoclave.

Example 16 The treatment of Example 10 was carried out using a lower rigid sheet of aluminum alloy with a minimum thickness of 3 mm. The surface of this plate in contact with the sanderch structure and the polyvinyl butyral resin was subjected to a pretreatment, first degreased and thoroughly dried, and then a precoat of silicone (Union Carbide Y4310) applied by spraying or brushing. After applying it,
Dry for 30 minutes at a temperature of 125-130 °C.

[Brief explanation of drawings]

FIG. 1 is a plan view of a photocell panel according to the present invention, FIG. 2 is an enlarged sectional view taken along the dashed line - in FIG. 1, and FIG. 3 is a plan view of a photocell panel according to another embodiment of the present invention. FIG. 4 is a cross-sectional view of the panel, FIG. 4 is a diagram showing one step of panel manufacturing in the method of the present invention, and FIG. 5 is a schematic diagram for explaining the preforming operation according to the method of the present invention. FIG. In these figures: 1...panel, 2...photocell element, 3...
Conductive strip, 4... Connection strip, 5...
Layers 6 and 7... hard sheet, 8 and 9... plastic sheet; 10... elastic bag, 11... tube, 12...
...Autoclave; 15...Mold, 16...
Hard part (or element), 17... Partition plate, 18...
... sharp end, 19 ... conveyor, 20 ... scraper, 21 ... shaping cylinder, 22 ... collector, 23 ... tunnel furnace, 24 ... preform,
25...It is a recessed part.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a panel of a plurality of electrically connected photocells having a lower surface, a side surface and a light-receiving surface, the method comprising: (a) for a preform having a relief for forming a recess in the photocell; filling a mold with thermoplastic resin powder, flattening the upper surface of the resin powder, and heating the mold to a temperature higher than the sintering temperature of the resin powder to form a sintered resin preform; (b) removing the preform from the mold; (c) placing the preform on a rigid sheet with the recess facing upward, and burying the photocell in the recess; (d) placing the preform with the photocell buried in the recess; A second hard sheet is applied on the molded body to form a sandwich-like aggregate, in which case the hard sheet covering at least the light-receiving surface of the photocell is optically transparent, and (e) step (d) ) The laminate obtained in step ) is placed in an elastic bag, and (f) the inside of the elastic bag is evacuated, a relatively high pressure is applied to the outside of the bag, and the temperature inside the bag is increased to heat the bag. The plastic resin preform was melted, and (g) the contents of the bag were cooled to solidify the resin, thereby forming a panel with photocells bound and embedded in the solidified resin between rigid sheets. A method for manufacturing a solar cell panel, which includes the step of taking out the panel from the bag into the atmosphere. 2. A step of inserting an optically transparent thermoplastic material sheet between the photocell embedded in the preform in step (c) and the hard sheet covering the light-receiving surface of the photocell in step (d). 2. The method according to claim 1, further comprising: the thermoplastic material sheet being adhesive to the resin material of the resin powder and the hard sheet. 3. A method according to claim 1 or 2, wherein the photocell and its electrical connection means are completely embedded in the preform in step (c). 4. An optically transparent thermoplastic resin sheet in which one of the hard sheets is covered with a thermoplastic resin powder layer, and the light-receiving surface of the photocell can be bonded to the resin material of the resin powder and the second hard sheet. A method according to claim 1, which is covered by: 5. After housing the photocell in the recess, the sintered resin preform is covered with a second sintered resin preform having no recess, and a second hard sheet is applied thereto to form a laminate. The method described in Scope 1. 6. The method of claim 5, wherein the first preform has a single recess containing an electrically connected photocell. 7. The method according to claim 1, 2, 3 or 4, wherein the hard sheet covering the light receiving surface of the photocell is an optically transparent glass sheet. 8 Claim 1, wherein the thermoplastic resin powder in step (a) is polyvinyl butyral resin;
The method according to paragraph 2, paragraph 3 or paragraph 4.