DE102009055031A1 - Back contact-solar cell for use in solar module, has perforated film and semi-conducting layer positioned on each other, and contact points whose portion is connected with conductive layer via solderless electrically conductive connection - Google Patents

Abstract

The solar cell (1) has a single or multi-layered perforated film made of electrically non-conductive material and including multiple holes. A structured electrically conductive layer is connected with a surface of the perforated film that is isolated on a semi-conducting layer. The perforated film and the semi-conducting layer are positioned on each other such that a portion of the holes and two sets of contact points (6, 7) face each other. A portion of the contact points is connected with the conductive layer via a solderless electrically conductive connection. An independent claim is also included for a method for manufacturing a solar cell.

Description

The invention relates to a solar cell, a solar module comprising this solar cell and to processes for their production and for producing a contact foil.

Conventional solar cells consist of a layer structure which is formed in a plate-shaped semiconductor material, for example monocrystalline or multicrystalline silicon. The semiconductor material forms the p-type base. By diffusion of phosphorus, a thin n-type layer, the so-called emitter, is produced on the surface. Usually, the base is contacted by means of a full-surface applied aluminum layer. The emitter is contacted via narrow fingers, which are interconnected by one or more so-called busbars. Since the metallic fingers and busbars do not allow light to enter the contacted areas of the cell, but too small a number and width of fingers increases the series resistance, fingers and busbars must be designed to minimize electrical losses and shadowing losses. The spatial separation of the emitter contact (front, the solar radiation facing) and base contact (back) complicates the interconnection of individual solar cells to form a module, since the front and back contact of two adjacent solar cells are soldered consuming each. While conventional solar cells have contact points on the front and the back, which are usually connected to band-shaped conductors, back-contacting solar cells allow simpler Verschaltungskonzepte.

To increase the efficiency, so-called back-contact solar cells have been developed, in which the emitter on the front side is electrically conductively connected to the emitter contact located on the rear side. Shading losses due to metal traces on the front can be minimized.

The WO 2007/096752 A2 describes a method for contacting back contact solar cells, wherein the contacting through the holes of a mounted on the solar cell perforated, electrically insulating film is carried out by means of wave soldering. This method has the disadvantage of a comparatively high temperature load on the solar cell and the use of a solder, which must first be melted.

Object of the present invention is to provide a solar cell of the type Rückkontaktakttsolarzelle and a corresponding solar module with a plurality of back-contact solar cells, in which a simple, inexpensive contacting and electrical interconnection of solar cells can be realized. Another object of the invention is to provide a process for producing this solar cell.

The solution of this object is achieved according to this invention by a solar cell, a solar module and a method for producing the solar cell according to the corresponding independent claims. Finally, the solution of this problem is achieved by a method for producing a contact foil strip, which is particularly suitable for producing the solar cell according to the invention. Preferred embodiments of the solar cell according to the invention are listed in corresponding dependent claims. Preferred embodiments of the solar cell according to the invention correspond to preferred embodiments of the solar module according to the invention and vice versa, although this is not explicitly stated herein. The same applies to the materials and films or layers present in the solar cell according to the invention and used in the process according to the invention.

• (a) eine halbleitende Schicht mit einer ersten Oberfläche und einer zweiten Oberfläche, wobei auf der ersten Oberfläche eine Vielzahl von ersten Kontaktstellen und zweiten Kontaktstellen ausgebildet sind, welche entgegengesetzte Polaritäten aufweisen;
• (b) eine auf einem Teil der ersten Oberfläche angeordnete Kontaktfolie, umfassend (b1) eine erste ein- oder mehrschichtige, perforierte Folie aus einem elektrisch nicht leitenden Material, die eine Vielzahl von ersten Löchern aufweist; und (b2) eine strukturierte elektrisch leitende Schicht auf einer der halbleitenden Schicht abgewandten Oberfläche der perforierten Folie b1;

wobei die perforierte Folie b1 und die halbleitende Schicht a so zueinander positioniert sind, dass zumindest ein Teil der ersten Löcher und der ersten Kontaktstellen und der zweiten Kontaktstellen einander gegenüber liegen, und wobei mindestens ein Teil der ersten Kontaktstellen und der zweiten Kontaktstellen über eine lotfreie elektrisch leitende Verbindung mit der strukturierten elektrisch leitenden Schicht verbunden sind.The invention thus relates to a solar cell comprising the following layers:

• (a) a semiconductive layer having a first surface and a second surface, wherein on the first surface are formed a plurality of first pads and second pads having opposite polarities;
• (b) a contact foil disposed on a portion of the first surface, comprising (b1) a first monolayer or multilayer perforated foil of an electrically nonconductive material having a plurality of first holes; and (b2) a structured electrically conductive layer on a surface of the perforated foil b1 facing away from the semiconducting layer;

wherein the perforated foil b1 and the semiconducting layer a are positioned to each other such that at least a part of the first holes and the first pads and the second pads face each other, and at least a part of the first pads and the second pads are electrically conductive via a solderless conductive connection are connected to the structured electrically conductive layer.

"Lot-free electrically conductive connection" generally means that the electrically conductive connection contains no material (solder), which has a lower melting point than the parts to be joined.

In a preferred embodiment, the contact foil is disposed to less than 90%, preferably to 40 to 75% and even more preferably to 50 to 60% of the first surface of the semiconducting layer.

The contact foil, which is partially arranged on the first surface of the semiconducting layer, can be used in the solar cell in different geometrical shapes. Preferably, the contact foil is arranged in the form of at least one contact foil strip on the first surface of the semiconductive layer.

In a preferred embodiment of the invention, a plurality of parallel equidistant contact foil strips are arranged on the first surface of the semiconductive layer.

For example, in the case of a solar cell having a substantially square base area with a side length of 10 cm to 25 cm, a contact foil consisting of 2 to 6 contact foil tapes with a width in the range of 0.5 to 3 cm in each case can be used.

In the semiconducting layer, the customary materials known to those skilled in the art can be used.

The electrically conductive layer may consist of a plurality of electrically conductive materials, as long as this material does not impair the function of an electrically conductive layer in a solar cell. The electrically conductive layer may in particular consist of a metal or an electrically conductive organic polymer.

As metals for the electrically conductive layer, it is preferable to use noble metals, aluminum and aluminum alloys, copper, titanium, or silver. Aluminum, aluminum alloys and copper are particularly preferably used, and very particularly preferably aluminum or aluminum alloys are used. It can be connected to each other the same metals as well as different metals. A multilayer structure (eg Al / Cu) is also possible.

Particularly suitable electrically conductive organic polymers have chains with conjugated double bonds. Among these, those derived from a substituted polythiophene are again preferred, the substituents preferably having C ₁ -C ₁₀ -alkyl or alkoxy groups.

Ultrasonic welding is particularly well suited for bonding the aforementioned metals. By means of ultrasonic welding, it is also possible to produce a connection between electrically conductive thermoplastics with one another or with a metal.

The electrically conductive layer preferably has a thickness of 0.05 to 0.2 mm and is in particular an aluminum or copper foil.

The term "single or multilayer film" used herein is to be interpreted broadly; it comprises a single film of a particular material, e.g. As a polyethylene terephthalate (PET) film, but also a laminate, which consists of several connected films. The term "layer" as used herein can therefore also have the meaning of foil.

In the case where a single-layered or multi-layered perforated film is perforated by punching to form a plurality of first holes and the resulting perforated film is laminated with an electrically conductive layer, a polyethylene terephthalate film is preferably used. Such a monolayer film is also referred to herein as an insulator film.

In the case where a multilayered film is used as the first single-layered or multi-layered perforated film, the materials preferably used are EVA (ethylene-vinyl acetate) polymer and polyethylene terephthalate. One of these layers or foils is also referred to herein as insulator film. This insulator film is preferably a polyethylene terephthalate film.

The first single-layer or multi-layer perforated film made of a non-conductive material may contain a backsheet as a backcoat for protecting the solar cell or a solar module containing the solar cell from environmental influences. The backside coating preferably contains a fluorine-containing polymer, in particular a polyvinyl fluoride (PVF). A particularly suitable polyvinyl fluoride is available under the name Tedlar ^® from Dupont. The backside coating may be single or multi-layered, e.g. B. a PVF polyester PVF composite.

The use of a multilayer film as the first single-layer or multi-layer film is preferred according to the invention, since in a preferably soft insulator film used (also referred to as melt film), the punching process is facilitated. An EVA film is soft and is therefore preferably punched together with a supporting second film.

The films or layers used in the first single or multilayer film have preferably a thickness of 0.01 to 0.5 mm, more preferably from 0.2 to 0.4 mm.

The first single or multilayer film is generally bonded to the electrically conductive layer with an adhesive. Such adhesives are known per se.

In a preferred embodiment of the solar cell according to the invention, the solder-free electrically conductive connection comprises a contact band between the part of the first and second contact points and the structured electrically conductive layer.

The material of the contact band is generally selected from the same materials as that of the electrically conductive layer. The size of the contact band is preferably matched to the size of the first and a second hole described below, which preferably have a hole size corresponding to a diameter of 1 to 10 mm, in particular from 2 to 5 mm. Here, the distance between the holes is generally taken into account, so that with a larger distance between the holes usually a larger contact band can be used.

Moreover, it is preferred that the solderless electrically conductive connection comprises an electrically conductive adhesive or is obtainable by ultrasonic welding.

The electrically conductive connection can advantageously also be obtained by laser welding. In this case, a hold-down device for the electrically conductive layer is preferably used, so that electrically conductive layer and contact points can touch. At the point where the laser beam passes the hold-down, the hold-down is generally transparent or the hold-down has a recess here.

In general, the solar cell of the invention has, in addition to the already mentioned layers (semiconductive layer, first single-layer or multi-layer perforated foil, structured electrically conductive layer), further layers. Thus, the solar cell preferably on the second surface of the semiconductive layer on a second single- or multi-layer film, the z. Example, an antireflection layer (eg., Of silicon nitride) and / or a further protective film (eg., From ethylene-vinyl acetate polymer). Finally, on the second single or multilayer film is generally still a transparent disc, for. B. made of glass or polycarbonate, preferably made of glass.

The thickness of the semiconducting layer is preferably 20 to 500 μm and most preferably 80 to 220 μm. The thickness of the first single-layer or multi-layer perforated film is preferably 20 to 400 μm. The thickness of the patterned electrically conductive layer is preferably 5 to 200 μm.

Most preferably according to the invention, the solderless electrical connection is obtainable by ultrasonic welding.

Ultrasonic welding, with or without simultaneous heat input, is a form of welding in which kinetic energy is used in the form of friction, which generally results from an oscillating relative translational movement of the parts to be joined under the influence of a static pressure. In comparison, friction is used in friction welding, which is mainly caused by a rotating or oscillating relative movement of the parts to be joined under the action of a static pressure. While according to the invention, in principle, friction welding can also be used to produce the electrically conductive connection, ultrasound welding is particularly preferred.

In general, an ultrasonic welder includes a lower electrode (referred to as "anvil") and an upper electrode (called a "sonotrode"). The sonotrode executes vibrations in a connection plane of the surfaces to be connected with a frequency of generally 10 to 200 kHz, preferably from 30 to 100 kHz. The amplitude is generally in the range of 1 to 50 microns and the power generally in the range of 0.01 to 1 kW, with the welding times are generally between 0.1 and 1 sec. The direction of vibration of the ultrasound and the direction of force are generally perpendicular to each other, with the surfaces to be joined rubbing against each other. Preferably, the use of welding consumables is dispensed with.

According to the invention it is preferred if the ultrasonic welding takes place without supplying additional heat energy. However, the ultrasonic welding can also be carried out with the supply of additional heat energy, for example, by the anvil is electrically heated.

For the concentrated introduction of the ultrasonic energy sonotrode and anvil can be adapted to the respective connection form.

The achievable strength of the electrically conductive connection depends on several parameters. In particular, the type of materials to be welded, the welding power and amplitude of the welding system and the nature of sonotrode and anvil are taken into account. As material for the sonotrode and the anvil can many different materials are used as long as the purpose of the invention is achieved.

For the concentrated introduction of the ultrasonic energy sonotrode and anvil can be adapted to the particular shape of the intended electrically conductive connection. This can also take into account whether the materials to be joined must first be physically brought into contact with each other. Thus, in a particularly preferred embodiment of the invention, the structured electrically conductive layer is pressed by means of an ultrasonic welding device on the first contact points and the second contact points of the semiconductive layer.

In a preferred embodiment of the solar cell according to the invention, the solderless electrical connection is a direct connection between the first and second contact points or a part thereof and the structured electrically conductive layer. "Direct connection" here means, in particular, that there is no further material between the first or second contact point and the structured electrically conductive layer. The direct connection can preferably be produced by ultrasonic welding.

The invention furthermore relates to a solar module which has a large number of the solar cells described above. The solar cells are generally arranged adjacent to each other and electrically connected to each other. On the back, d. H. the side facing away from the solar radiation side of the solar cell are arranged in a predetermined arrangement, for example in a matrix arrangement, a plurality of first contact points of a first polarity and second contact points of opposite polarity spaced from each other. The contact portions of opposite polarity are executed interleaved, in accordance with the layout of the associated contact points to be contacted.

Preferably, the contact points of the same polarity on the back of the solar cell per polarity are arranged alternately in parallel rows. A contact foil made of the first single- or multilayer, perforated foil and the structured electrical layer can connect a single row of solar cells (so-called string) or an entire solar module. By partially etching away the electrically conductive layer, for. As a metal foil made of aluminum or copper, conductor tracks, which connect the solar cells after the preferred ultrasonic welding in the desired manner, for example in a series circuit to achieve a higher voltage or in parallel to achieve a higher amperage of the electric current generated in the light of the solar cell , Combinations of these circuits are also possible.

Suitable connection arrangements for the electrical connection of solar cells are for example in the WO 2008/113741 A described.

• (a) eine halbleitende Schicht mit einer ersten Oberfläche und einer zweiten Oberfläche, wobei auf der ersten Oberfläche eine Vielzahl von ersten Kontaktstellen und zweiten Kontaktstellen ausgebildet sind, welche entgegengesetzte Polaritäten aufweisen;
• (b) eine auf einem Teil der ersten Oberfläche (4) angeordnete Kontaktfolie (27), umfassend (b1) eine erste ein- oder mehrschichtige, perforierte Folie aus einem elektrisch nicht leitenden Material, die eine Vielzahl von ersten Löchern aufweist; und (b2) eine strukturierte elektrisch leitende Schicht auf einer der halbleitenden Schicht a abgewandten Oberfläche der perforierten Folie b1; wobei die erste ein- oder mehrschichtige perforierte Folie b1 und die halbleitende Schicht a so zueinander positioniert sind, dass zumindest ein Teil der ersten Löcher und der ersten Kontaktstellen und der zweiten Kontaktstellen einander gegenüber liegen, und wobei mindestens ein Teil der ersten und zweiten Kontaktstellen über eine lotfreie elektrisch leitende Verbindung mit der strukturierten elektrisch leitenden Schicht verbunden sind, und wobei
• (d) auf einem Teil der ersten Oberfläche der halbleitenden Schicht eine erste ein- oder mehrschichtige, perforierte Folie aus einem elektrisch nicht leitenden Material, die eine Vielzahl von ersten Löchern aufweist, aufgebracht wird, und auf dieser perforierten Folie eine elektrisch leitende Schicht aufgebracht wird, wobei die perforierte Folie auf der halbleitenden Schicht so aufgebracht wird, dass zumindest ein Teil der ersten Löcher und der ersten Kontaktstellen und der zweiten Kontaktstellen einander gegenüber liegen;
• (e) die elektrisch leitende Schicht strukturiert wird; und
• (f) die dadurch erhaltene strukturierte elektrisch leitende Schicht durch die ersten Löcher hindurch über eine lotfreie elektrisch leitende Verbindung mit den ersten Kontaktstellen und den zweiten Kontaktstellen verbunden wird.

Finally, the subject matter of the invention is a process for producing a solar cell, which comprises the following layers:

• (a) a semiconductive layer having a first surface and a second surface, wherein on the first surface are formed a plurality of first pads and second pads having opposite polarities;
• (b) one on a part of the first surface ( 4 ) arranged contact foil ( 27 comprising (b1) a first single or multi-layer perforated foil of an electrically non-conductive material having a plurality of first holes; and (b2) a structured electrically conductive layer on a surface of the perforated foil b1 facing away from the semiconductive layer a; wherein the first single- or multi-layer perforated sheet b1 and the semiconductive layer a are positioned to each other such that at least a part of the first holes and the first contact pads and the second contact pads face each other, and at least a part of the first and second contact pads overlap a solderless electrically conductive connection is connected to the structured electrically conductive layer, and wherein
• (D) on a portion of the first surface of the semiconductive layer, a first single- or multi-layer perforated sheet of an electrically non-conductive material having a plurality of first holes, is applied, and on this perforated film, an electrically conductive layer is applied wherein the perforated film is deposited on the semiconductive layer such that at least a portion of the first holes and the first contact pads and the second contact pads face each other;
• (e) the electrically conductive layer is patterned; and
• (F) the resulting structured electrically conductive layer is connected through the first holes through a solder-free electrically conductive connection with the first contact points and the second contact points.

"Structuring the electrically conductive layer" means that parts are removed from an originally compact electrically conductive layer, so that only those parts of the originally compact electrically conductive layer remain behind, which are relevant for an intended contacting of contact points. This can be done, for example, by providing the electrically conductive layer with a cover layer in such a way that only the structures of the later-obtained structured electrically conductive layer are provided with the cover layer. The parts of the electrically conductive layer not provided with the covering layer can then be removed, for example, in a suitable etching bath.

The structured electrically conductive layer is preferably connected to the first contact points and the second contact points by ultrasonic welding or friction welding, particularly preferably by ultrasonic welding.

In a preferred embodiment of the invention, a first monolayer or multilayer film of one or more electrically non-conductive materials is perforated by punching to form a plurality of first holes, and the resulting first monolayer or multilayer perforated film is laminated with an electrically conductive layer ,

In a particularly preferred embodiment of the method according to the invention, the structured electrically conductive layer is pressed through the first holes on the first contact points and the second contact points and then connected by ultrasonic welding the structured electrically conductive layer with the first contact points and the second contact points. Here, the pressing of the structured electrically conductive layer on the first contact points and the second contact points is preferably carried out with an ultrasonic welder. For this purpose, the sonotrode may be designed at its tip suitable to ensure optimum pressing.

The first holes preferably have a round shape. When the structured electrically conductive layer is pressed down, therefore, a circular cutout of the electrically conductive layer is generally pressed down. To reduce mechanical stresses can be provided that before pressing down on both sides of a remaining web each a circle section is punched out.

In an alternative embodiment of the method according to the invention, the electrically conductive layer is provided by punching with a plurality of second holes, so that the second holes are located above the first holes; a contact band is disposed between the portion of the first pads and the second pads and the patterned electrically conductive layer; and generates a solderless electrically conductive connection.

The first and / or second holes may have different cross sections. Preferably, both the first holes and the second holes have a circular cross-section.

The size of the first holes and / or the second holes generally corresponds to a circle having a diameter between 1 and 10 mm, preferably between 2 and 5 mm, wherein the first holes and the second holes preferably have the same cross-section.

According to the invention, the distance between the holes (first and second holes) and / or between the contact points is preferably 1 to 15 cm and more preferably 3 to 7 cm.

In the solar cells according to the invention or in the process according to the invention for their production, the production of second holes, preferably by punching the electrically conductive layer to form second holes in the electrically conductive layer, before or after structuring the metallically conductive layer, for example in a Etching bath, done.

The contact band is applied over the second holes and brought into physical contact with the semiconductive layer by depression. Here, the physical contact can be direct or indirect. In an indirect contact is located between the contact strip and the semiconducting layer and / or the electrically conductive layer, for example, a per se known electrically conductive adhesive. The contact band is generally connected at two locations to the patterned electrically conductive layer and at a location having the semiconductive layer. At these three points, an electrically conductive connection can be realized by various methods such as gluing or ultrasonic welding. Preferably, the same type of connection is used for all three points, so that, for example, the contact band is connected to the electrically conductive layer in two places by means of ultrasonic welding and at one point with the semiconductive layer.

The possibly electrically conductive adhesive can be applied to the cells or the contact foil by dispensing or screen printing. They may be single-component or multi-component adhesives which cure at room temperature, at elevated temperature, under pressure or under UV radiation.

• (g) eine erste ein- oder mehrschichtige Folie aus einem oder mehreren elektrisch nicht leitenden Materialien bereitgestellt wird;
• (h) die erste ein- oder mehrschichtige Folie mit einer elektrisch leitenden Schicht verbunden wird;
• (i) auf mindestens einem Teil der elektrisch leitenden Schicht eine Abdeckschicht aufgebracht wird;
• (j) die nicht mit der Abdeckschicht versehenen Teile der elektrisch leitenden Schicht in einem Ätzbad entfernt werden; und
• (k) durch Stanzen mindestens die erste ein- oder mehrschichtige Folie mit einer Vielzahl von ersten Löchern versehen wird; und wobei das Stanzen gemäß Schritt (k) nach jedem der Schritte (g) bis (j) durchgeführt werden kann; und die erste ein- oder mehrschichtige Folie und/oder die elektrisch leitende Schicht mit einer Breite von 0,5 cm bis 3 cm bereitgestellt werden oder in einem Schritt
• (l) auf eine Breite von 0,5 cm bis 3 cm geschnitten werden.

The invention also relates to a method for producing a contact foil tape having a width of 0.5 cm to 3 cm, comprising a first single-layer or multi-layer perforated foil made of an electrically non-conductive material having a plurality of first holes and a structured electrically conductive layer, wherein

• (g) providing a first monolayer or multilayer film of one or more electrically non-conductive materials;
• (h) bonding the first single or multilayer film to an electrically conductive layer;
• (i) a covering layer is applied to at least part of the electrically conductive layer;
• (j) removing the portions of the electrically conductive layer not provided with the capping layer in an etching bath; and
• (k) by punching at least the first single- or multi-layer film is provided with a plurality of first holes; and wherein the stamping according to step (k) can be performed after each of the steps (g) to (j); and the first single- or multi-layered film and / or the electrically conductive layer are provided with a width of 0.5 cm to 3 cm or in one step
• (l) cut to a width of 0.5 cm to 3 cm.

A contact foil in the sense of the present invention is an at least two-layered foil in which a layer of an electrically conductive material and a further layer of an electrically insulating material are formed.

The application of the covering layer is preferably carried out by applying an overcoat to protect the parts of the electrically conductive layer which are not to be etched away in the etching bath. The top coat can be applied by various methods, for example by spraying, spraying or screen printing. In particular, in the case where the overcoat is applied over the entire surface, the method is not particularly limited. On the other hand, if specific structures are to be protected from etching, the cover color is preferably applied by screen printing.

The etching bath consists of chemical substances which allow the etching away of the non-protected parts of the electrically conductive layer. The composition of the etching bath therefore depends on the type of metal used or the electrically conductive polymer.

Subsequent to the etching step (j) in the etching bath, a cleaning of the contacting film can be carried out, for example, in a further bath (immersion bath). The stamping of the foil can be carried out between the etching step and the cleaning of the resulting contacting foil or after the cleaning of the laminate of structured electrical layer and first single- or multilayer foil after passing through the etching bath. A cleaning step after the etching bath may, in particular, involve the removal of the covering layer (eg, topcoat color) from the protected areas and / or constituents of the etching bath.

Preferably, in the method according to the invention for producing a contact foil, a first monolayer or multilayer foil is used which has a self-adhesive isolator foil on both sides, on one side of which a second monolayer or multilayer foil, e.g. B. a back sheet is arranged, and on the other side a release film, for. As a siloxane liner is applied. In this case, it is preferable for the first monolayer or multilayer film to be provided with an adhesive on a surface to be joined to the electrically conductive layer.

When using a second single-layer or multi-layered film, the stamping of the insulator foil is facilitated, in particular if the first single- or multilayered foil consists only of the insulator foil.

The present invention enables solar cells to be efficiently connected with a very good electrically conductive connection between the layer used for power generation, i. H. the semiconductive layer, and the electrical wiring used to derive the generated solar power can be equipped.

In addition, the present invention enables back contact solar cells to be electrically connected to a flexible printed circuit (contact sheet) in an optimum manner while being correctly positioned and fixed to each other.

Further details of the invention will become apparent from the following description of non-limiting embodiments of the solar cell according to the invention and the inventive method. Reference is made to the 1 to 6 ,

1 shows a section of a solar module 3 according to the present invention, in a linear array, a plurality of solar cells 1 according to the present invention.

2 shows in a perspective view of a section of a solar cell three juxtaposed variants according to the invention for electrically conductive connections between the electrically semiconductive layer and the structured electrically conductive layer.

3 shows a section through a solar cell according to an embodiment of the present invention.

4 shows a section through a solar cell according to another embodiment of the present invention.

5 shows a perspective view of a first embodiment of a method according to the invention for producing a contact foil tape.

6 shows a perspective view of a second embodiment of a method according to the invention for producing a contact foil tape.

1 shows a section of a solar module 3 according to the present invention, in a linear array, a plurality of solar cells 1 having. Three solar cells 1 are by means of three contact foil strips 35 connected with each other. The mutually parallel contact foil strips 35 cover only a part of the here not closer apparent first surface of the solar cells 1 , On every solar cell 1 There are first (positive) contact points 6 and second (negative) contact points 7 , which are arranged in the embodiment shown here in mutually parallel rows. At the in 1 shown solar module 3 is the average solar cell by 180 ° with respect to the neighboring solar cells 1 turned so that towards a contact foil tape 35 For example, on the top contact foil tape 35 first (positive) contact points 6 on the left solar cell 1 , second (negative) contact points 7 on the middle solar cell 1 and again first (positive) contact points 6 are arranged on the right solar cell.

Along a contact foil tape 35 are on a solar cell the negative and positive contact points through an insulating area 36 electrically isolated from each other. The first contact points 6 positive polarity, however, are in the solar cell shown on the left 1 electrically conductive with a first contact finger 33 connected and the second contact points 7 Negative polarity are electrically conductive in the solar cell shown in the middle with a second contact finger 34 connected. First contact finger 33 and second contact finger 34 are in contact foil tape 35 included, which thus produces an electrical connection of the two solar cells in the form of a series connection. In an analogous way, these two solar cells with further, in 1 not shown solar cells connected.

The size of the first holes 9 is at the in 1 shown embodiment of the invention each 4 mm, wherein the distance between the first holes 9 in the embodiment shown here is 6 cm. Other sizes and distances are possible.

At the in 1 shown solar cell is used as the material of the semiconductive layer of crystalline silicon.

2 shows in a perspective view of a section of a solar cell three juxtaposed variants of the invention for electrically conductive connections 11 between the electrically semiconductive layer 2 and the patterned electrically conductive layer 10 through a perforated foil 8th therethrough. In practice, however, only one of these variants is usually used on a solar cell or a solar module. All variants have in common that on a semiconducting layer 2 with a first surface 4 and a second surface 5 on the first surface 4 arranged first and second contact points 6 . 7 different polarity are. Since the nature of the polarity has no effect on the electrical connection, it is not specified here.

At the in 2 left first variant is an electrically conductive connection 11 realized in that a on a structured electrically conductive layer 10 located contact band 12 through a first hole 9 in the perforated foil 8th and a second hole 19 in the structured electrical layer 10 with a first or second contact point 6 . 7 the semiconducting layer 2 electrically connected.

At the in 2 in the middle shown second variant becomes an electrically conductive connection 11 between the patterned electrically conductive layer 10 and the semiconductive layer 2 through one out of the structured layer 10 punched out bridge 27 realized on a first or second contact point 6 . 7 the semiconducting layer 2 pressed and electrically conductively connected by means of ultrasonic welding. In the second variant, there is the second hole 19 thus from two circular section-shaped openings.

At the right in 2 In the embodiment shown, an electrical connection is realized by the structured electrically conductive layer 10 through the first hole 9 through to a first or second contact point 6 . 7 the semiconducting layer 2 is pressed, for example, using a suitably shaped sonotrode of an ultrasonic welder, and then electrically connected by ultrasonic welding.

The electrically conductive connection 11 will be at the three in 2 variants produced by ultrasonic welding. However, it is also conceivable that between the structured electrically conductive layer 10 and the semiconductive layer 2 an electrically conductive adhesive is applied, which realizes the electrical connection. In the first Variant can be the contact band 12 also by means of an electrically conductive adhesive with the structured electrically conductive layer 10 on the one hand and with the semiconducting layer 2 on the other hand be electrically connected. The electrically conductive adhesive could in this case, for example, before or after joining the perforated film 8th with the semiconducting layer 2 on the contact points 6 and 7 be applied.

3 shows a section through a solar cell according to an embodiment of the present invention. In 3 is the side facing away from the solar radiation of the solar cell above and the solar radiation side facing down. Starting from the side facing away from the solar radiation, initially a protective layer 31 (Back Sheet, for. Example, a PVF as Tedlar ^®), a structured electrically conducting layer 10 , a perforated electrically non-conductive layer 8th with first holes 9 , a semiconducting layer 2 , a second single or multilayer film 14 that z. Example, an antireflection layer and / or an ethylene-vinyl acetate polymer film comprises as a further protective layer, and a glass sheet 15 arranged.

At the in 3 shown embodiment of a solar cell according to the invention is an electrically conductive compound 11 according to the second or third variant of 2 realized by the structured electrically conductive layer 10 directly through a first hole 9 through with a first or second contact point 6 . 7 on the semiconducting layer 2 connected is. The connection 11 was made by ultrasonic welding or laser welding.

4 shows a section through a solar cell according to another embodiment of the present invention, wherein the solderless electrical connection 11 with the help of a contact band 12 is realized. The layer sequence corresponds to that in 3 shown. In 4 left is the first variant of 2 to see in section. The solderless electrical connection 11 was produced in the first variant by means of ultrasonic welding or laser welding. Right is in 4 a fifth variant for the solderless electrical connection 11 shown in which a contact band 12 by means of an electrically conductive adhesive 16 both with the structured electrically conductive layer 10 as well as with a first or second contact point 6 . 7 on the semiconducting layer 2 is electrically connected.

5 shows a perspective view of a first embodiment of a method according to the invention for producing a contact foil tape. The arrow indicates the direction of movement of the slides.

In this embodiment, a single-layer or multi-layered film is a single-layered film 17 used. The one-layer film coming from a supply roll 17 is in a punching device 21 punched and then in an adhesive applicator 22 coated on the subsequently to be connected with an electrically conductive layer side with adhesive. After coating with adhesive, the first holes will be used 9 provided perforated foil 8th with a metal foil coming from another roll as the electrically conductive layer 18 brought together. By means of the laminating rollers 24 an intimate bond is created between the two films. The perforated foil 8th opposite surface of the metal foil 18 is then in a first screen printing device 23 at certain points to be protected with a covering layer 29 provided, which has the function that before a Wegätzung in an etching bath 20 Protected locations of the electrically conductive metal foil 18 to protect. There is then a further transport of the film laminate to a second screen printing device 32 in which the back of the electrically conductive layer 18 full surface with a cover layer 29 is provided. Subsequently, the film laminate treated in this way passes into an etching bath 20 where the unprotected parts of the metal foil 18 be etched away and only the desired conductor structures of the structured electrically conductive layer 10 stay. The resulting contact foil 27 is then about transport roles 25 transported further, for example in a cleaning bath, not shown here, to the contacting film 27 adhering residues of the etching bath 20 and / or the cover layer 29 to remove.

6 shows a perspective view of a second embodiment of a method according to the invention for producing a contact foil.

At the in 6 shown second embodiment of the method according to the invention for producing a contact foil is a self-adhesive isolator film on both sides 13 holding a release liner on one side 26a initially, with a melt film 30 laminated. The lamination is done by the laminating rollers 24 supported. The resulting monolayer or multilayer film 17 one or more electrically nonconductive materials is then placed in a punching device 21 punched. Then the stamped release film 26b withdrawn upward while the single or multi-layer perforated film 28 of an electrically non-conductive material with a metal foil coming from another roller as the electrically conductive layer 18 is brought together. Using the laminating rollers 24 an intimate bond of these two films is produced. Subsequently, that of the multilayer perforated film 28 opposite surface of the metal foil 18 in a first screen printing device 23 on in front of a path etching Protected areas with a cover layer 29 provided, which has the function that before a Wegätzung in an etching bath 20 Protected locations of the electrically conductive metal foil 18 to protect. There is then a further transport of the film laminate to a second screen printing device 32 in which the back of the electrically conductive layer 18 full surface with a cover layer 29 is provided. Subsequently, the film laminate treated in this way passes into an etching bath 20 where the unprotected parts of the metal foil 18 be etched away and only the desired conductor structures of the structured electrically conductive layer 10 stay. The Kontaktierfolie obtained as contact foil tape 27 is about transport roles 25 transported further, for example, by a not shown here cleaning bath (dip) to the contact foil tape 27 adhering residues of the etching bath 20 and / or the cover layer 29 to remove.

LIST OF REFERENCE NUMBERS

1

solar cell

2

Semiconductive layer

3

solar module

4

First surface of the semiconducting layer

5

Second surface of the semiconducting layer

6

First contact points (positive polarity)

7

Second contact points (negative polarity)

8th

Perforated foil of an electrically non-conductive material

9

First holes (in insulating layer)

10

Structured electrical conductive layer

11

Electrically conductive connection

12

Contact band

13

Self-adhesive isolator film on both sides

14

"Intermediate film"

15

pane

16

Electrically conductive adhesive

17

First single or multi-layer film (insulating)

18

Electrically conductive layer

19

Second holes (in electrically conductive layer)

20

etching bath

21

A perforator

22

Klebstoffauftragungsgerät

23

First screen printing device

24

laminating

25

transport wheels

26a

release film

26b

Perforated release film

27

Contact sheet

28

Perforated single or multilayer film

29

covering

30

melting foil

31

protector

32

Second screen printing device

33

first contact finger

34

second contact finger

35

Contact foil tape

36

insulating area

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2007/096752 A2 [0004]
• WO 2008/113741 A [0042]

Claims (16)

Solar cell ( 1 ) comprising the following layers: (a) a semiconducting layer ( 2 ) with a first surface ( 4 ) and a second surface ( 5 ), where on the first surface ( 4 ) a plurality of first contact points ( 6 ) and second contact points ( 7 ) are formed, which have opposite polarities; (b) one on a part of the first surface ( 4 ) arranged contact foil ( 27 ) comprising (b1) a first single-layer or multi-layer perforated film ( 8th . 28 ) of an electrically non-conductive material having a plurality of first holes ( 9 ) having; and (b2) a structured electrically conductive layer ( 10 ) on one of the semiconductive layers ( 2 ) facing away from the surface of the perforated film b1 ( 8th . 28 ); the perforated foil b1 ( 8th . 28 ) and the semiconducting layer a ( 2 ) are positioned to each other such that at least a portion of the first holes ( 9 ) and the first contact points ( 6 ) and the second contact points ( 7 ) are opposite one another, characterized in that at least a part of the first contact points ( 6 ) and the second contact points ( 7 ) via a solderless electrically conductive connection ( 11 ) with the structured electrically conductive layer ( 10 ) are connected. Solar cell ( 1 ) according to claim 1, characterized in that the contact foil ( 27 ) to less than 90% of the first surface ( 4 ) of the semiconductive layer ( 2 ) is arranged. Solar cell ( 2 ) according to claim 1 or 2, characterized in that the contact foil ( 27 ) in the form of at least one contact foil strip ( 35 ) on the first surface ( 4 ) is arranged. Solar cell ( 2 ) according to one of claims 1 to 3, characterized in that a plurality of parallel equidistant contact foil tapes ( 35 ) on the first surface ( 4 ) are arranged. Solar cell ( 1 ) according to one of claims 1 to 4, characterized in that the solder-free electrically conductive compound ( 11 ) a contact band ( 12 ) between the part of the first and second contact points ( 6 . 7 ) and the structured electrically conductive layer ( 10 ). Solar cell ( 1 ) according to one of claims 1 to 5, characterized in that the solder-free electrically conductive compound ( 11 ) an electrically conductive adhesive ( 16 ). Solar cell ( 1 ) according to one of claims 1 to 6, characterized in that the solder-free electrically conductive compound ( 11 ) is available by ultrasonic welding or by laser welding. Solar cell ( 1 ) according to one of claims 1 to 7, characterized in that the solder-free electrically conductive compound ( 11 ) a direct connection between the part of the first and second contact points ( 6 . 7 ) and the structured electrically conductive layer ( 10 ). Solar module ( 3 ) comprising a plurality of solar cells ( 1 ) according to one of claims 1 to 8. Solar module ( 3 ) according to claim 9, characterized in that adjacent solar cells ( 1 ) are arranged so that first contact points ( 6 ) and second contact points ( 7 ) are opposite. Process for producing a solar cell ( 1 ) comprising the following layers: (a) a semiconducting layer ( 2 ) with a first surface ( 4 ) and a second surface ( 5 ), where on the first surface ( 4 ) a plurality of first contact points ( 6 ) and second contact points ( 7 ) are formed, which have opposite polarities; (b) one on a part of the first surface ( 4 ) arranged contact foil ( 27 ) comprising (b1) a first single-layer or multi-layer perforated film ( 8th . 28 ) of an electrically non-conductive material having a plurality of first holes ( 9 ) having; and (b2) a structured electrically conductive layer ( 10 ) on one of the semiconductive layers ( 2 ) facing away from the surface of the perforated film ( 8th . 28 ); the perforated foil ( 8th . 28 ) and the semiconducting layer ( 2 ) are positioned to each other such that at least a portion of the first holes ( 9 ) and the first contact points ( 6 ) and the second contact points ( 7 ) are opposite each other, and wherein at least a portion of the first and second contact points ( 6 . 7 ) via a solderless electrically conductive connection ( 11 ) with the structured electrically conductive layer ( 10 ), characterized in that (d) on a part of the first surface ( 4 ) of the semiconductive layer ( 2 ) a first single-layer or multi-layer perforated film ( 8th . 28 ) of an electrically non-conductive material having a plurality of first holes ( 9 ) is applied, and on this perforated film ( 8th . 28 ) an electrically conductive layer ( 18 ), the perforated film ( 8th . 28 ) on the semiconductive layer ( 2 ) is applied so that at least a portion of the first holes ( 9 ) and the first contact points ( 6 ) and the second contact points ( 7 ) are opposite each other; (e) the electrically conductive layer ( 18 ) is structured; and (f) the structured electrically conductive layer ( 10 ) through the first holes ( 9 ) through a solderless electrically conductive compound ( 11 ) with the first contact points ( 6 ) and the second contact points ( 7 ) is connected. A method according to claim 11, characterized in that the structured electrically conductive layer ( 10 ) by ultrasonic welding or by laser welding with the first contact points ( 6 ) and the second contact points ( 7 ) is connected. A method according to claim 11 or 12, characterized in that a first single or multilayer film ( 17 ) of one or more electrically non-conductive materials by punching to form a plurality of first holes ( 9 ) is perforated and the resulting first single- or multi-layer perforated film ( 8th ) with an electrically conductive layer ( 18 ) is laminated. Method according to one of claims 11 to 13, characterized in that the structured electrically conductive layer ( 10 ) through the first holes ( 9 ) through to the first contact points ( 6 ) and the second contact points ( 7 ) and then by ultrasonic welding the structured electrically conductive layer ( 10 ) with the first contact points ( 6 ) and the second contact points ( 7 ) is connected. Method according to one of claims 11 to 14, characterized in that the electrically conductive layer ( 18 ) by punching with a plurality of second holes ( 19 ), so that the second holes ( 19 ) over the first holes ( 9 ) lie; a contact band ( 12 ) between the part of the first contact points ( 6 ) and the second contact points ( 7 ) and the structured electrically conductive layer ( 10 ) is attached; and a solderless electrically conductive connection ( 11 ) is produced. Method for producing a contact foil tape ( 35 ) having a width in the range of 0.5 cm to 3 cm, comprising a first single- or multi-layer perforated film ( 8th . 28 ) of an electrically non-conductive material having a plurality of first holes ( 9 ) and a structured electrically conductive layer ( 10 ), characterized in that (g) a first monolayer or multilayer film ( 17 ) is provided from one or more electrically non-conductive materials; (h) the first single or multilayer film ( 17 ) with an electrically conductive layer ( 18 ) is connected; (i) on at least part of the electrically conductive layer ( 18 ) a cover layer ( 29 ) is applied; (j) not with the covering layer ( 29 ) provided parts of the electrically conductive layer ( 18 ) in an etching bath ( 20 ) are removed; and (k) by punching at least the first single or multilayer film ( 17 ) with a multiplicity of first holes ( 9 ) is provided; wherein the stamping according to step (k) can be performed after each of the steps (g) to (j); and the first single or multilayer film ( 17 ) and / or the electrically conductive layer ( 18 ) are provided with a width in the range of 0.5 cm to 3 cm or cut in a step (l) to a width in the range of 0.5 cm to 3 cm.

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