WO2014005802A1

WO2014005802A1 - Method for sealing a contact hole of a photovoltaic module

Info

Publication number: WO2014005802A1
Application number: PCT/EP2013/061985
Authority: WO
Inventors: Hans-Werner Kuster; Dieter Kleyer
Original assignee: Saint-Gobain Glass France
Priority date: 2012-07-02
Filing date: 2013-06-11
Publication date: 2014-01-09
Also published as: EP2867925A1

Abstract

The present invention relates to a method for sealing a contact hole of a photovoltaic module, comprising at least the following steps: (a) providing a photovoltaic module (M) containing a laminated composite consisting of a backing plate (2), photovoltaic layer system (3) and front plate (1) arranged on top of one another, wherein the front plate (1) and/or the rear plate (2) has at least one contact hole (5) which is suitable for leading through an electrically conductive connecting element; (b) producing a reduced pressure (p) in the contact hole (5); and (c) introducing a sealant (6), which has a viscosity of 600 mPa*s to 1000 mPa*s measured at 23°C, into the contact hole (5).

Description

Method for sealing a contact hole of a photovoltaic module

The invention relates to a method for sealing a contact hole of a photovoltaic module, a device for carrying out the method and their use.

Thin-film photovoltaic modules typically include a front panel facing the incident light and a rearward-facing disc connected to the front panel via a thermoplastic interlayer, with a photovoltaic panel facing the inside surface of the front pane (superstrate configuration) or rear pane (substrate configuration) Layer system is applied. Photovoltaic modules are known, whose rear pane or front pane has one or more contact holes. The contact holes are provided for the passage of electrical conductors to electrically contact the photovoltaic layer system. Such photovoltaic modules are disclosed for example in EP 1041647 A1, WO 20091 12503 A1 and US 20100243047 A1.

Through the contact holes there is a risk of moisture entering the photovoltaic module, which can lead to corrosion of the photovoltaic layer system. To avoid this, the holes are typically provided with a sealant. Suitable sealing agents are, for example, butyl sealants or epoxy sealants, as disclosed in WO 20091 12503 A1.

When filling viscous sealants, such as butyl sealants of the prior art, air can be trapped. In particular, air bubbles can form between the sealant and the photovoltaic layer system. In this case, the penetration of further air and moisture into the photovoltaic module is prevented by the sealant, however, the already trapped air can lead to corrosion of the photovoltaic layer system or connected to this electrically conductive elements.

The object of the present invention is to provide an improved method for sealing a contact hole of a photovoltaic module, in which the air inclusion in the sealing means is effectively reduced. The object of the present invention is further to provide a device suitable for carrying out the method. The object of the present invention is achieved by a method for sealing a contact hole of a photovoltaic module according to independent claim 1. Preferred embodiments will become apparent from the dependent claims.

The method according to the invention for sealing a contact hole of a photovoltaic module comprises at least the following method steps:

(a) providing a photovoltaic module comprising a laminated composite of superimposed rear pane, photovoltaic layer system and front pane, the front pane and / or the rear pane having at least one contact hole suitable for the passage of an electrically conductive connecting element,

(b) generating a reduced pressure p in the contact hole and

(c) introducing a sealant having a measured at 23 ° C viscosity of 600 mPa * s to 1000 mPa * s, in the contact hole.

For the purposes of the invention, the front pane is the pane of the photovoltaic module facing the light incidence. Rear window is the disc facing away from the light incident. The front disk and the rear disk each have an outside and an inside surface. The inside surfaces of the front disk and the rear disk are facing each other and connected to each other via a thermoplastic intermediate layer by lamination.

The inventive method differs from the prior art in that the sealing means is not filled at ambient pressure, but at the reduced pressure p in the contact hole. It has surprisingly been found that, as a result, the inclusion of air during the introduction of the sealing means can be effectively prevented. The formation of air bubbles between sealing and photovoltaic layer system is advantageously avoided. As a result, the risk of corrosion of the photovoltaic layer system and of further corrosion-prone elements in the interior of the laminated photovoltaic module can be significantly reduced or even completely prevented. That is a great advantage of the invention.

The sealant according to the invention has a viscosity of 600 mPa ^* s to 1000 mPa ^* s. In the context of the invention, viscosity is understood to mean the dynamic viscosity, which is measured at a temperature of 23 ° C. In this range for the viscosity On the one hand, the sealing means can advantageously be introduced into the contact hole and, on the other hand, leads to a permanent sealing of the contact hole against the ingress of air and moisture. The viscosity of the sealing agent is preferably from 700 mPa * s to 900 mPa ^* s, more preferably from 750 mPa ^* s to 850 mPa ^* s, for example about 800 mPa ^* s. This results in particularly good results with regard to the introduction of the sealing means and the permanent sealing of the contact hole.

The sealant preferably contains elastic, moisture-sealing polymers, particularly preferably at least polyisobutylene, polybutylene, polyisobutyleneisoprene (in particular as so-called butyl rubber), polysulfide, polyurethane, silicone or combinations thereof. The sealing agent very particularly preferably comprises at least polyisobutylene, polybutylene or polyisobutyleneisoprene (in particular as so-called butyl rubber). This is particularly advantageous in view of the sealing effect of the sealant against air and moisture.

The photovoltaic module is preferably arranged horizontally when introducing the sealing means in the contact hole. This means that the front screen and the rear screen are aligned approximately parallel to the ground. The contact hole points upwards.

In the contact hole, an amount of sealing agent is preferably introduced such that a layer of the sealing means with a height of at least 0.05 mm is formed in the contact hole when the photovoltaic module is arranged in a horizontal position. This achieves an advantageous sealing effect against air and moisture. The required amount of sealing agent is to be determined by the skilled person in dependence on the geometric dimensions of the contact hole in a simple manner. The height of the layer of the sealing agent is particularly preferably from 0.05 mm to 1 mm, very particularly preferably from 0.1 mm to 0.5 mm and in particular from 0.15 mm to 0.3 mm. This is particularly advantageous in view of the sealing effect as well as the economical and thus cost-effective use of the sealant.

According to the invention, a reduced pressure p is generated in the contact hole before the introduction of the sealing means. The sealing agent is introduced into the contact hole under this reduced pressure p. For the purposes of the invention, a reduced pressure refers to a pressure which is lower than the ambient pressure. The reduced pressure p is preferably from 0.5 bar to 0.95 bar, more preferably from 0.8 bar to 0.95 bar, most preferably from 0.85 bar to 0.95 bar, for example about 0.9 bar. Such a reduced pressure can be produced without great technical effort and advantageously leads to an avoidance of air inclusions in the sealing means.

The sealing means is preferably heated to an elevated temperature before being introduced into the contact hole. The temperature of the sealing agent is preferably from 50 ° C to 150 ° C, more preferably from 80 ° C to 120 ° C and most preferably from 90 ° C to 1 10 ° C. Due to the elevated temperature, the viscosity of the sealing means is reduced, so that the sealing means can be easily introduced into the contact hole, spreads quickly over the base of the contact hole and thus seals the contact hole.

The reduced pressure in the contact hole is preferably generated by means of a vacuum bell. This is to be understood as a device in the manner of a hood or chamber, which is designed to be open on one side, wherein the edges bounding the open side are arranged in one plane. The vacuum bell can be placed over the open side on a portion of the surface of the disc, the area containing the contact hole. This means that the edges of the vacuum bell, over which the vacuum bell is in contact with the disc, surround the contact hole with a suitable distance. The open side of the vacuum bell is thus sealed by the disc, so that a closed space formed by the vacuum bell and the area of the disc is formed. A sufficiently tight connection between vacuum bell and disc can be achieved by means of a suitable seal, for example made of rubber or plastic.

The vacuum bell is preferably made of a transparent material and contains, for example, at least glass or a transparent plastic. The transparent material may include, for example, polyethylene, polypropylene, polycarbonate, polymethyl methacrylate, polystyrene, polyamide, polyester, polyvinyl chloride, and / or mixtures thereof. A transparent vacuum bell has the advantage that the filling of the sealant can be observed and controlled from the outside. In principle, however, the vacuum bell can also consist, for example, of a metal or an alloy, for example steel. The vacuum bell preferably has a wall thickness of 0.3 mm to 10 mm, more preferably from 0.5 mm to 4 mm, most preferably from 1 mm to 2 mm. The vacuum bell preferably has a volume content of from 3 cm ³ to 200 cm ³ , more preferably from 5 cm ³ to 20 cm ³ , particularly preferably from 8 cm ³ to 10 cm ³ . Smaller vacuum bells can only handle unfavorably, because the introduction of the sealant is difficult. Larger vacuum bells are less space-saving and require a lot of effort to produce the reduced pressure. The vacuum bell is not limited to a particular shape. The vacuum bell may, for example, have a round or rectangular base. The base area is for example from 5 cm ² to 15 cm ² . The height of the vacuum bell is for example from 0.5 cm to 3 cm.

The vacuum bell further has at least one opening, to which a vacuum line, for example a hose can be attached. The vacuum line connects the vacuum bell with a vacuum pump. By means of the vacuum pump, the reduced pressure within the vacuum bell, and thus within the contact hole, can be generated.

In an advantageous embodiment, the vacuum bell has a further opening through which an injection device can be passed. About the injection device, the sealing means can be introduced into the contact hole. The injection device is preferably formed substantially tubular, for example in the manner of a hollow needle. The opening of the vacuum bell, through which the injection device is guided, is preferably sealed with a suitable seal, for example made of rubber. The opening for the passage of the injection device is preferably arranged opposite the open side provided for sealing by the pane of the photovoltaic module. As a result, the sealing means can be easily introduced into the contact hole by means of the injection device. In a preferred embodiment, the injection device is already passed through the opening of the vacuum bell when generating the reduced pressure. In principle, however, also initially the reduced pressure can be generated, wherein the opening of the vacuum bell is sealed, for example, with a rubber seal, and the injection device are then inserted through the opening. The vacuum bell and the injection device may alternatively be formed in one piece.

The injection device is preferably connected outside of the vacuum bell with a reservoir for the sealing means. The connection between injection device and reservoir preferably takes place via a sealing medium line, for example a hose. Thus, for example, by means of a pump, a defined amount of the sealing agent can be conducted from the reservoir to the injection device. Alternatively, the injection device and the reservoir may also be designed, for example, in the manner of a syringe.

In an advantageous embodiment, the injection device has a heating function. The heating function can be achieved for example by heating coil, which are arranged around the injection device. The heating coil can be arranged inside and / or outside the vacuum bell around the injection device. By the heating coil, the sealing means can be heated to a desired temperature within the injection device. The particular advantage is that only a very small amount of time passes between the heating of the sealing means and the introduction of the sealing means into the contact hole. The sealing means can therefore no longer significantly cool before being introduced into the contact hole.

Alternatively, however, the sealing means can also be heated already in the storage container or within the connection between storage container and injection device.

In an advantageous embodiment, a contact hole according to the invention has a diameter of 1 mm to 20 mm, preferably of 2 mm to 10 mm and particularly preferably of 4 mm to 6 mm.

In an advantageous embodiment, the transition between on the one hand the contact hole and on the other hand, the inside surface and / or the outside surface of the disc, which has the contact hole, provided with a chamfer. Beveling reduces the risk of damaging the disc with the via hole in the manufacture of the photovoltaic module, such as cracks. The chamfer has, for example, an angle of 30 ° to 60 °, in particular about 45 ° to the surface of the disc. The depth of the chamfer, measured from the surface of the disc, is for example, from 0.2 mm to 1 mm. In the area of the chamfer, it is particularly easy to form air bubbles when the sealing agent is introduced under ambient pressure, which can lead to corrosion of the photovoltaic layer structure. The inventive method, in which the formation of air bubbles is avoided, is therefore particularly advantageous for such photovoltaic modules. As the diameter of the contact hole in the context of the invention, the diameter in the region not provided with the chamfer applies.

The front pane of the photovoltaic module preferably contains a non-prestressed, partially prestressed or tempered or a hardened, for example a thermally or chemically hardened glass. The front pane preferably contains soda-lime glass, low-iron soda-lime glass or borosilicate glass. This is particularly advantageous in terms of the stability of the photovoltaic module, the protection of the photovoltaic layer system from mechanical damage and the transmission of sunlight through the front pane.

The rear pane of the photovoltaic module contains, in an advantageous embodiment, a non-prestressed, partially prestressed or prestressed or a hardened, for example a thermally or chemically hardened glass. The rear pane preferably contains soda-lime glass, low-iron soda-lime glass or borosilicate glass. Alternatively, however, the rear pane can also contain, for example, a plastic, for example polyethylene, polypropylene, polycarbonate, polymethyl methacrylate and / or mixtures thereof, a glass-fiber-reinforced plastic, a metal or a metal alloy, for example stainless steel.

The front pane and the rear pane preferably have a thickness of 1 mm to 10 mm, particularly preferably 2 mm to 5 mm. The area of the front pane and the rear pane can be from 100 cm ² to 18 m ² , preferably from 0.5 m ² to 3 m ² . The front and rear wheels can be flat or curved.

The contact hole can be arranged in the front pane or in the rear pane. Preferably, the contact hole is arranged in the rear window. Thus, the electrically conductive connecting element can be elegantly guided on the side facing away from the light incident side of the photovoltaic module and connected there to the outer lead, without the photovoltaically active surface is shadowed by elements of electrical contact. The photovoltaic layer system effects the charge carrier separation required for the conversion of radiant energy into electrical energy. The photovoltaic layer system preferably comprises at least one photovoltaically active absorber layer between a front electrode layer and a back electrode layer. The front electrode layer is arranged on the side facing the incidence of light absorber layer. The back electrode layer is arranged on the side facing away from the light incident side of the absorber layer.

The photovoltaically active absorber layer according to the invention is not limited to a specific type. In an advantageous embodiment, the photovoltaic module is a thin-film photovoltaic module. These are understood as layer systems with thicknesses of only a few micrometers. In principle, all absorber layers familiar to the person skilled in the art for thin-film photovoltaic modules can be used. The absorber layer may contain, for example, amorphous or micromorphous silicon, semiconducting organic polymers or oligomers, cadmium telluride (CdTe), gallium arsenide (GaAs) or cadmium selenide (CdSe). In a preferred embodiment, the absorber layer contains a p-type chalcopyrite semiconductor such as a compound of the group copper indium sulfur / selenium (CIS), for example copper indium diselenide (CulnSe ₂ ), or a compound of the group copper indium gallium Sulfur / selenium (CIGS), for example Cu (InGa) (SSe) ₂ . The inventive method is particularly advantageous for CI (G) S-based photovoltaic modules, because they are particularly sensitive to penetrating oxygen. The absorber layer preferably has a layer thickness of 500 nm to 5 μιη, more preferably from 1 μιη to 3 μιη. The absorber layer can be doped with metals, preferably sodium.

The absorber layer can also contain, for example, monocrystalline or polycrystalline silicon.

The back electrode layer may contain, for example, at least one metal, preferably molybdenum, titanium, tungsten, nickel, titanium, chromium and / or tantalum. The back electrode layer preferably has a layer thickness of 300 nm to 600 nm. The back electrode layer may comprise a layer stack of different individual layers. The layer stack preferably contains a diffusion barrier layer For example, silicon nitride, to prevent diffusion of, for example, sodium from the substrate into the photovoltaically active absorber layer.

The front electrode layer is transparent in the spectral region in which the absorber layer is sensitive. The front electrode layer may contain, for example, an n-type semiconductor, preferably aluminum-doped zinc oxide or indium-tin oxide. The front electrode layer preferably has a layer thickness of 500 nm to 2 μm.

The electrode layers may also contain silver, gold, copper, nickel, chromium, tungsten, tin oxide, silicon dioxide, silicon nitride and / or combinations and mixtures thereof.

The photovoltaic layer system preferably has a peripheral distance to the outer edges of the photovoltaic module of 5 mm to 20 mm, particularly preferably from 10 mm to 15 mm, in order to be protected against ingress of moisture or shading by fasteners on the edge.

The photovoltaic layer system may be applied on the inside surface of the rear pane (substrate configuration). The photovoltaic layer system may alternatively be applied to the inside surface of the front pane (superstrate configuration). The photovoltaic layer system may also be incorporated in the thermoplastic layer, for example between a first and a second film of the intermediate layer.

The inventive method leads in particular to a significant reduction in the risk of corrosion when the contact hole is arranged in the disc on which the photovoltaic layer system is deposited. The contact hole is preferably arranged in the not provided with the photovoltaic layer system edge region of the disc.

In a preferred embodiment, the photovoltaic module according to the invention has the substrate configuration. In particular, when the contact hole is arranged in the rear pane, a photovoltaic layer system applied to the rear pane is threatened by corrosion due to air and moisture trapped in the sealing means. The inventive method, the inclusion of air and moisture in the sealant reduced or avoided entirely, then leads to a particularly advantageous reduced risk of corrosion.

The photovoltaic layer system is divided in an advantageous embodiment of the invention with known methods for producing a thin-film solar module by a suitable structuring and interconnection of back electrode layer, semiconductor layer, and front electrode layer into individual photovoltaically active areas, so-called solar cells. A suitable method is known, for example, from EP 2200097 A1. The subdivision is made by incisions using a suitable structuring technology such as laser writing and mechanical processing, for example by lifting or scribing. The individual solar cells are connected in series via an area of the back electrode layer in integrated form.

For electrically contacting the photovoltaic layer system, at least two electrically conductive connecting elements are provided, which are each connected to the front and / or back electrode layer in an electrically conductive manner. The photovoltaic module may have a single contact hole through which the two electrically conductive connecting elements are guided. However, the photovoltaic module can also have two contact holes, wherein each electrically conductive connecting element is guided through one of the contact holes.

Preferably, each of the two electrically conductive connecting elements is electrically conductively connected via a bus bar to the front and / or rear electrode layer. The bus bar is advantageously designed as a band or strip. The bus bar contains at least one metal or metal alloy or consists of a metal or a metal alloy. In principle, any electrically conductive material that can be processed into films can be used for the bus bar. Particularly suitable materials for the bus bar are, for example, aluminum, copper, tin-plated copper, gold, silver or tin and alloys thereof. The bus bar has, for example, a thickness of 0.01 mm to 0.5 mm and a width of 2 mm to 16 mm. An electrically conductive connection between the bus bars and the respective electrode layer takes place, for example, by welding, bonding, soldering, clamping or gluing by means of an electrically conductive adhesive. A bus bar is preferably connected to the positive voltage terminal of the photovoltaic module and the second bus bar connected to the negative voltage terminal of the photovoltaic module.

The contact point of the bus bar with the electrically conductive connecting element is preferably located in the middle of the extension direction of the bus bar. As a result, a more homogeneous distribution of the current flow and a lower maximum current density in the region of the current pick-off is achieved than with an electrical contact at one end of the bus bar. This allows the use of bus bars with a smaller cross-sectional area, for example, with a smaller width. By using narrower busbars, the photovoltaically active area can be increased and the area-dependent power can be increased.

The contact hole is preferably arranged above the contact point of the busbar. This means that the projection of the contact hole on the bus bar contains the contact point. The electrically conductive connecting element can then advantageously be led out of the photovoltaic module on the shortest possible path through the contact hole.

If the photovoltaic layer system is subdivided into individual solar cells which are connected in series with one another, the two electrically conductive connection elements are preferably electrically conductively connected only to the back electrode layer. The resulting positive and the resulting negative voltage terminal of the photovoltaic module are then passed over the back electrode layer and contacted there electrically. For this purpose, the two bus bars are preferably each applied to the back electrode layer and electrically conductively connected to the back electrode layer. Alternatively, however, the positive and negative voltage connections can also be routed via the front electrode layer and contacted there electrically. Alternatively, a voltage connection can also be made via the back electrode layer and the second voltage connection via the front electrode layer.

The electrically conductive connecting elements can be guided in time before or after the introduction of the sealing material through the contact hole or the contact holes. The electrically conductive connecting elements can be formed as wires, cables, strands or flat conductors. In this case, the electrically conductive connecting elements are preferably connected to the photovoltaic layer system via the thermoplastic intermediate layer prior to laminating the front pane and the rear pane and guided through the contact hole or the contact holes. The sealing means is preferably introduced into the contact hole or the contact holes after lamination. The connection between the electrically conductive connecting elements and the bus bars can be effected, for example, by welding, bonding, soldering, clamping or by means of an electrically conductive adhesive.

In an advantageous embodiment, the electrically conductive connecting elements are designed as contact pins or spring contact element. In this case, the electrically conductive connecting elements can advantageously be arranged after the introduction of the sealing means in the contact hole or the contact holes. The sealing agent is penetrated by the electrically conductive connecting elements. It is preferred that a solderless, clamping connection between the electrically conductive connecting elements and preferably the bus bars produced. Suitable spring contact elements are known for example from US 20100243047 A1. The bus bars must be arranged within the laminated photovoltaic module so that a contact after lamination and introduction of the sealant is possible. The bus bar is preferably arranged in area over the contact hole directly on the disc having the contact hole arranged.

The connection of the electrically conductive connecting element to the bus bar can also be effected via a bridging element, for example a suitably arranged further strip of an electrically conductive foil, which is in contact with the actual bus bar.

If the photovoltaic layer system is not applied directly to the surface of the pane which is provided with the contact hole, then the electrically conductive connecting elements and / or the bus bars and / or bridging elements are preferably conducted before the lamination of the photovoltaic module by feedthroughs of the thermoplastic intermediate layer , so that an electrical contacting of the photovoltaic layer system through the at least one contact hole is possible therethrough. This is the case, for example, with a photovoltaic module in superstrate Configuration in which the at least one contact hole is arranged in the rear window.

The contact hole is preferably closed on the outside surface of the disk, which has the contact hole, with a connection housing known per se or a junction box. Such junction boxes are known from DE 10 2005 025 632 A1 and DE 10050614 C1. Inside the junction box, the electrically conductive connection elements are preferably connected to external supply lines.

The front pane is connected to the rear pane via at least one thermoplastic intermediate layer. The connection between the front screen and the return tickets takes place over a large area via the photovoltaic layer system. The intermediate layer preferably contains thermoplastic materials, such as polyvinyl butyral (PVB) and / or ethylene vinyl acetate (EVA) or several layers thereof, preferably with thicknesses of 0.3 mm to 0.9 mm. The intermediate layer may also include polyurethane (PU), polypropylene (PP), polyacrylate, polyethylene (PE), polycarbonate (PC), polymethylmethacrylate, polyvinyl chloride, polyacetate resin, casting resins, acrylates, fluorinated ethylene-propylenes, polyvinyl fluoride, ethylene-tetrafluoroethylene, copolymers and / or mixtures thereof.

A suitable photovoltaic module can be produced by methods known per se. The photovoltaic layer system can be applied to the front pane or the rear pane, for example, by sputtering, vapor deposition or chemical vapor deposition (CVD). The photovoltaic layer system can also be arranged between a first and a second thermoplastic film.

The front pane and / or the rear pane are provided with the contact hole or the contact holes before or after the application of the photovoltaic layer system by drilling. The bore is preferably provided with chamfers in the region of the surface of the disc.

The bonding of the front disk to the rear disk via the thermoplastic intermediate layer typically takes place under the action of heat, vacuum and / or pressure, for example by autoclave method, vacuum bag method, vacuum ring method, calender method, vacuum laminator or by combinations thereof. Prior to laminating the photovoltaic module, bus bars are preferably suitably arranged in the composite and connected to the photovoltaic layer system.

The object of the invention is further achieved by a device for carrying out the method according to the invention, comprising at least

- A vacuum bell, which is arranged on a contact hole containing region of the front disk or the rear disk and generates the reduced pressure p in the contact hole, and

- An injected through an opening of the vacuum bell injection device, which introduces the sealing means in the contact hole.

The device according to the invention is used in particular in an arrangement for sealing a contact hole of a photovoltaic module. The arrangement according to the invention comprises at least:

a photovoltaic module comprising a laminated composite of superimposed rear pane, photovoltaic layer system and front pane, the front pane and / or the rear pane having at least one contact hole suitable for the passage of an electrically conductive connecting element,

- A vacuum bell, which is arranged on a contact hole containing region of the front pane or the rear disk and generates a reduced pressure p in the contact hole, and

- An injected through an opening of the vacuum bell injection device which introduces a sealing means in the contact hole, wherein the sealing means has a measured at 23 ° C viscosity of 600 mPa ^* s to 1000 mPa ^* s.

Another aspect of the invention comprises the use of a device according to the invention for sealing a contact hole of a photovoltaic module, in particular of a thin-film photovoltaic module. The device is used in particular for carrying out the method according to the invention. For this purpose, the vacuum bell is arranged on a region of the front disk or the rear disk which contains the contact hole, generates the reduced pressure p in the contact hole and inserts the sealing means into the contact hole with an injection device guided through an opening of the vacuum bell. The invention will be explained in more detail with reference to a drawing and exemplary embodiments. The drawing is a schematic representation and not to scale. The drawing does not limit the invention in any way. Show it:

1 shows a cross section through a arranged on a photovoltaic module embodiment of the device according to the invention during the introduction of the sealing means,

2 shows a cross section through the device and the photovoltaic module according to FIG

1 after the introduction of the sealant,

Fig. 3 shows an embodiment of the method according to the invention with reference to a

Flowchart.

1 shows a cross section through an area of a photovoltaic module M and an apparatus according to the invention arranged thereon during the method according to the invention. The photovoltaic module M comprises a front pane 1, a rear pane 2 and a photovoltaic layer system 3, which is applied to the inside surface of the rear pane 2. The rear pane 2 and the front pane 1 are interconnected over a large area via the photovoltaic layer system 3 by means of a thermoplastic intermediate layer 4. The front pane 1 is transparent to sunlight and consists of tempered, extra-white glass with low iron content. The rear window 2 is made of soda lime glass. The front disk 1 and the rear disk 2 have a thickness of, for example, 1, 6 mm to 2.85 mm. The photovoltaic module M has a size of 1587 mm x 664 mm. The intermediate layer 4 contains polyvinyl butyral (PVB) and has a layer thickness of 0.76 mm.

The photovoltaic layer system 3 comprises a rear electrode layer 10 arranged on the rear pane 2, which contains molybdenum and has a layer thickness of approximately 300 nm. The photovoltaic layer system 3 further comprises a photovoltaically active absorber layer 1 1, which contains sodium-doped Cu (InGa) (SSe) ₂ and has a layer thickness of about 2 μιη. The photovoltaic layer system 3 further includes a front electrode layer 12 containing aluminum-doped zinc oxide (AZO) and having a layer thickness of about 1 μιη. Between front electrode layer 12 and absorber layer 1 1, a buffer layer, not shown, is arranged, which contains a single layer of cadmium sulfide (CdS) and a single layer intrinsic zinc oxide (i-ZnO). The buffer layer causes an electronic adjustment between absorber layer 1 1 and Front electrode layer 12. The photovoltaic layer system 3 is subdivided with known methods for producing a thin-film photovoltaic module into individual photovoltaically active regions, so-called solar cells, which are connected in series with each other over a region of the back electrode layer 10. The photovoltaic layer system 3 is mechanically abraded in the edge region of the back plate 2 with a width of 15 mm.

The rear pane 2 has, in the edge region not provided with photovoltaic layer system 3, two contact holes 5 which are provided for passing through electrically conductive connecting elements in order to electrically contact the photovoltaic layer system. In the illustrated area of the photovoltaic module M, one of these contact holes 5 can be seen. The contact hole 5 is covered on the inside surface of the rear disk 2 by a bus bar 16 which is in electrical contact with the return electrode 10. The bus bar 16 is intended to be contacted with the electrically conductive connector. The bus bar 16 is configured as a strip of copper having a thickness of, for example, 0.01 mm to 0.5 mm, a length of, for example, 1567 mm and a width of, for example, 4 mm to 16 mm.

The contact hole 5 has a diameter of 4.5 mm. The contact hole 5 is provided on the surfaces of the rear disk 2 with a chamfer at an angle of 45 °. The depth of the chamfer, measured from the respective surface of the rear disk 2, for example, 0.3 mm to 0.7 mm. By chamfering damage to the rear pane 2 in the manufacture of the photovoltaic module M, in particular from the contact hole 5 outgoing cracks can be effectively avoided. In order to prevent ingress of air and / or moisture into the photovoltaic module M through the contact hole 5, the contact hole 5 must be sealed with a sealing means 6.

According to the invention, the sealing means 6 is introduced under reduced pressure p a the contact hole. For this purpose, a vacuum bell 7 is arranged on the outside surface of the rear disk 2. In the figure, the photovoltaic module M is shown greatly enlarged compared to the vacuum bell 7 for clarity. The vacuum bell 7 is made of polymethyl methacrylate (PMMA) and has, for example, a round base with a diameter of 30 mm. The height of the vacuum bell 7 is 12 mm and the wall thickness 2 mm. The vacuum bell 7 is is arranged on a region of the surface of the rear disk 2 via a rubber seal 13, in the middle of which the contact hole 5 is located.

At an opening of the vacuum bell 7, a vacuum line 9 is attached, via which the vacuum bell 7 is connected to a vacuum pump, not shown. The reduced pressure p can be generated by the pump in the closed space formed by the vacuum bell 7 and the rear disk 2. The reduced pressure p is, for example, 0.8 to 0.9 bar.

Through an opening on the upper side of the vacuum bell 7, an injection device 8 is guided. The injection device 8 is designed as a hollow needle and connected outside the vacuum bell 7 via a sealant line 14 with a reservoir, not shown. The sealing means 6 can be introduced from the reservoir via the sealing medium line 14 and the injection device 8, for example by means of a suitable pump in the contact hole 5.

The sealant 6 is a preparation based on polybutylene (Henkel Terostat 2792) and has a dynamic viscosity of 800 mPa ^* s at 23 ° C. The sealing means 6 is introduced into the contact hole 5 at a temperature of about 100 ° C. For this purpose, heating coil 15 are arranged around the injection device 8. By means of the heating coil 15, the temperature of the sealing means 6 can advantageously be increased shortly before introduction into the contact hole 5. The sealing means 6 can alternatively or additionally already be heated in the storage container, for example in order to achieve a better transport through the sealing medium line 14 as a result of a reduced viscosity.

FIG. 2 shows the photovoltaic module M and the device according to the invention from FIG. 1 after introduction of the sealing means 6. The sealing means 6 forms a layer with a height of 0.2 mm in the contact hole 5 adjacent to the bus bar 16. By the sealing means 6, the penetration of air and moisture through the contact hole 5 is effectively prevented.

As a result of the introduction according to the invention under the reduced pressure p, the sealing means 6 is largely free of air inclusions. If the sealing means 6 introduced under ambient pressure, as is customary in the prior art, so air inclusions can form, which in particular as air bubbles in the region of the chamfer of the contact hole 5 can collect under the sealing means 6. Such air inclusions can lead to corrosion of the bus bar 16 and / or the photovoltaic system 3, whereby the efficiency of the photovoltaic module M is reduced. By the method according to the invention, therefore, the corrosion resistance and long-term stability of the photovoltaic module M is advantageously improved.

In the illustrated embodiment, the electrically conductive connecting element at the time of introduction of the sealing means 6 is not yet passed through the contact hole 5. The electrically conductive connecting element can be designed, for example, as a contact spring element, which is inserted through the contact hole 5 after the introduction of the sealing means 6 and brought into contact with the bus bar 16. In an alternative embodiment, the electrically conductive connecting element may for example be formed as a wire, which is already connected to the bus bar 16 at the time of introduction of the sealing means 6 and passed through the contact hole 5.

On the outside surface of the rear disk 2, the contact hole 5 can be closed later. For this purpose, for example, a known junction box on the back plate 2 above the contact hole 5 are arranged. In the junction box, the electrically conductive connection element can be connected to the outer supply line.

Fig. 3 shows an example of an embodiment of the method according to the invention for sealing a contact hole of a photovoltaic module.

In a series of experiments, sealed photovoltaic modules M and conventionally sealed photovoltaic modules were subjected to a standardized temperature-humidity test (damp heat test). The photovoltaic modules M were each constructed as shown in FIGS. 1 and 2. In the conventionally sealed modules, the sealant 6 (Henkel Terostat 2792) was introduced under ambient pressure into the contact hole 5, in the modules sealed according to the invention at a reduced pressure of 0.8 to 0.9 bar. It has been shown that the corrosion resistance of the bus bars 16 and the photovoltaic layer systems 3 was significantly improved in the photovoltaic modules M sealed according to the invention. This result was unexpected and surprising to the skilled person.

LIST OF REFERENCE NUMBERS

(1) front disk

(2) disc

(3) photovoltaic layer system

(4) Interlayer

(5) contact hole

(6) Sealant

(7) Vacuum bell

(8) injection device

(9) Vacuum line

(10) back electrode layer

(1 1) absorber layer

(12) front electrode layer

(13) Rubber seal

(14) Sealant line

(15) heating coil

(16) Busbars

(M) photovoltaic module

Claims

claims

A method of sealing a contact hole of a photovoltaic module, comprising at least

(A) providing a photovoltaic module (M) comprising a laminated composite of superimposed rear pane (2), photovoltaic layer system (3) and front pane (1), wherein the front pane (1) and / or the rear pane (2) at least have a suitable for performing an electrically conductive connection element contact hole (5),

(b) generating a reduced pressure p in the contact hole (5) and

(C) introducing a sealing agent (6), which has a measured at 23 ° C viscosity of 600 mPa ^* s to 1000 mPa ^* s, in the contact hole (5).

2. The method of claim 1, wherein the reduced pressure p by means of a vacuum bell (7) is generated, which on a contact hole (5) containing region of the front plate (1) or the rear disc (2) is arranged.

3. The method of claim 2, wherein the sealing means (6) by means of a through an opening of the vacuum bell (7) guided through injection device (8) is introduced into the contact hole (5).

4. The method according to any one of claims 1 to 3, wherein the viscosity of the sealing means (6) of 700 mPa ^* s to 900 mPa ^* s, preferably from 750 mPa ^* s to 850 mPa ^* s.

5. The method according to any one of claims 1 to 4, wherein the sealing means (6) at least polyisobutylene, polybutylene, polyisobutylene isoprene, polysulfide, polyurethane, silicone or combinations thereof.

6. The method according to any one of claims 1 to 5, wherein the sealing means (6) before step (c) to a temperature of 50 ° C to 150 ° C, preferably from 80 ° C to 120 ° C, particularly preferably from 90 ° C. is heated to 1 10 ° C.

7. The method according to any one of claims 1 to 6, wherein the reduced pressure p of 0.5 bar to 0.95 bar, preferably from 0.8 bar to 0.95 bar.

8. The method according to any one of claims 1 to 7, wherein in step (c) a layer of the sealing means (6) having a height of 0.05 mm to 1 mm, preferably from 0.1 mm to 0.5 mm, particularly preferred from 0.15 to 0.3 mm in the contact hole (5) is introduced.

9. The method according to any one of claims 1 to 8, wherein the contact hole (5) has a diameter of 1 mm to 20 mm, preferably from 2 mm to 10 mm, particularly preferably from 4 mm to 6 mm.

10. The method according to any one of claims 1 to 9, wherein the front disc (1) and / or the Rückscheibe (2) has a thickness of 1 mm to 10 mm, preferably from 2 mm to 5 mm, and preferably a non-prestressed, teilvorgespanntes or biased or a tempered glass, particularly preferably soda-lime glass, low-iron soda-lime glass or borosilicate glass.

11. The method according to claim 1, wherein the photovoltaic layer system has at least one photovoltaically active absorber layer between a front electrode layer and a back electrode layer, and wherein the photovoltaically active absorber layer contains at least copper indium (gallium) sulfur / selenium (CI (G) S).

12. An apparatus for carrying out the method according to any one of claims 1 to 1 1, comprising at least

- A vacuum bell (7) on a contact hole (5) containing region of the front disc (1) or the rear disc (2) is arranged and generates the reduced pressure p in the contact hole (5), and

- One through an opening of the vacuum bell (7) guided through injection device (8), which introduces the sealing means (6) in the contact hole (5).

13. The apparatus of claim 12, wherein inside and / or outside of the vacuum bell (7) heating coil (15) are arranged around the injection device (8).

14. The apparatus of claim 12 or 13, wherein the vacuum bell (7) at least glass, polyethylene, polypropylene, polycarbonate, polymethyl methacrylate, polystyrene, polyamide, polyester, polyvinyl chloride and / or mixtures thereof.

15. Use of a device according to one of claims 12 to 14 for sealing a contact hole (5) of a photovoltaic module M, in particular of a thin-film photovoltaic module.