DE102010006879A1 - Contacting a photovoltaic module, comprises providing a layer arrangement from a light-sensitive layer for generating a charge during falling light on the light-sensitive layer and a conductive layer arranged on the light-sensitive layer - Google Patents

Abstract

The method comprises providing a layer arrangement (100) from a light-sensitive layer (30) for generating a charge during falling light on the light-sensitive layer and a conductive layer (20) arranged on the light-sensitive layer for tapping a voltage, providing a conductor for contacting the conductive layer, providing a soldering material for soldering the conductor onto the conductive layer, and arranging the conductor and the soldering material on the layer arrangement, so that the soldering material is provided between the conductive layer and the conductor. The method comprises providing a layer arrangement (100) from a light-sensitive layer (30) for generating a charge during falling light on the light-sensitive layer and a conductive layer (20) arranged on the light-sensitive layer for tapping a voltage, providing a conductor for contacting the conductive layer, providing a soldering material for soldering the conductor onto the conductive layer, arranging the conductor and the soldering material on the layer arrangement, so that the soldering material is provided between the conductive layer and the conductor, arranging a temperature-regulating tool onto the conductor for heating the conductor, where the temperature-regulating tool is heated at a temperature that is 150-190[deg] C over the melting temperature of the soldering material, melting the soldering material, cooling and solidifying the soldering material, and connecting the conductor with the conductive layer. The soldering material has a melting temperature of 210-230[deg] C. The conductor is coated at a side with the soldering material. The temperature-regulating tool is pressed onto the conductor with a pressing force of 10-40 N for a time period of 500-700 ms, and is heated at a temperature of 390[deg] C. The conductive layer has a transparent conductive oxide. The method further comprises cleaning the temperature-regulating tool after a number of steps of the pressing of the temperature-regulating tool on the conductor, where the cleaning step takes place after each sixty to eighty steps of the pressing of the temperature-regulating tool on the conductor. The cleaning step takes place by mechanical or chemical effect on a surface of the temperature-regulating tool, which is pressed on the conductor during heating the conductor. An independent claim is included for a photovoltaic module.

Description

The invention relates to a method for contacting a photovoltaic module, in which a metallic layer, at which a voltage potential can be tapped at a light incident on the photovoltaic module, is contacted with a conductor. Furthermore, the invention relates to a photovoltaic module, on which a conductor for tapping a voltage is provided.

A photovoltaic module comprises a photosensitive layer in which charge carriers are generated when light is incident. The photosensitive layer is disposed between conductive layers between which a voltage is generated. The layer structure of the photosensitive layer and the conductive layers is arranged on a carrier substrate, which may be a glass pane, for example. One of the conductive layers may be arranged as a lower layer of the layer structure or as a front-side contact directly on the carrier substrate. The other upper conductive layer may be disposed as a backside contact on the photosensitive layer. For contacting the upper conductive layer, an electrical conductor is connected to the upper conductive layer. The conductor may for example be band-shaped and coated on both sides with a solder material.

For soldering the conductor to the upper conductive layer, the conductor with the side coated with the solder material is first placed on top of the upper conductive layer. For heating the solder material, a temperature-controlled tool, for example a thermode, with a heated contact surface is pressed onto the upper conductive layer. By pressing the heated thermode onto the band-shaped conductor, the solder material arranged on the underside of the conductor melts. The molten solder material is subsequently cooled and solidified. After the cooling phase, the conductor is connected to the conductive layer of the photovoltaic module.

When using a conductor coated on both sides with solder material, the thermode surface is in direct contact with the solder material of the coated conductor during the melting process. After the melting of the solder layer, the thermode sinks into the solder layer. This causes the thermode to be contaminated with solder material. As the thermode becomes more and more contaminated as the number of solders increases, the process parameters for subsequent solders change, so that the entire brazing process becomes inhomogeneous over an extended period of time, thereby degrading the quality of soldering as the number of solders increases.

In the soldering operation, a small contact area of the heated thermode is pressed onto the band-shaped conductor at a position where the soldering between the band-shaped conductor and the conductive layer is to be produced. Both the conductor and the support structure coated with the layer structure are at room temperature when the thermode contacts the conductor. Due to the high temperature difference during the soldering process between the layer arrangement of the layer structure and the carrier substrate on the one hand and the heated soldering components, such as the heated thermode surface, on the other hand arises in the material of the layer assembly in a region which is located below the thermode surface, a large temperature stress.

The temperature stress leads to the fact that the electrically active layers of the layer arrangement which contribute to the generation of the charge carriers can delaminate or break up. Furthermore, the conductive layers may partially melt, so that the two conductive layers are connected to each other by an ohmic contact. Due to the delamination of the layers or as a result of the ohmic contact forming between the conductive layers, however, the photocell formed from this layer structure is destroyed, so that no voltage is generated between the conductive layers despite the incident light on the photosensitive layer. The location of a photovoltaic module, at which the soldering takes place, therefore can not be used electrically in most cases. In general, an area of the layer arrangement of the carrier substrate and the layer structure arranged thereon which is projected below the contact surface of the thermode is concerned.

The object of the present invention is to specify a method for contacting a photovoltaic module, in which a conductive layer of the module, on which a voltage potential is generated in a photosensitive layer of the module due to the photovoltaic effect, is contacted with a conductor, whereby destruction a photocell, which is formed from the photosensitive layer and the conductive layer, can be largely avoided.

An embodiment of a method for contacting a photovoltaic module comprises providing a layer arrangement of a photosensitive layer for generating a charge upon the incidence of light on the photosensitive layer and a conductive layer arranged on the photosensitive layer for picking up a voltage. Furthermore, a conductor for contacting the conductive layer and a solder material for soldering the conductor on the conductive Layer provided. The conductor and the solder material are arranged on the layer arrangement such that the solder material is provided between the conductive layer and the conductor. A temperature controlled tool is placed on the conductor to heat the conductor, the temperature controlled tool being heated to a temperature between 150 ° C and 190 ° C above the melting temperature of the solder material. This melts the solder material. The solder material is cooled and solidified, thereby connecting the conductor to the conductive layer.

The heat for heating the conductive layer and the conductor can be generated by a temperature controlled tool, such as a thermode, which is pressed with its heated contact surface on the conductor. The temperature-controlled tool can be pressed onto the conductor for a period between 500 ms and 700 ms. The pressure force can be between 10 N and 40 N. In particular, if, for example, a solder material is used which contains tin or silver and for example has a melting temperature of about 221 ° C, the contact surface of the temperature-controlled tool, which is in contact with the conductor during pressing to a temperature between 370 ° C and 410 ° C, in particular to a temperature of 390 ° C are heated.

Due to the short time during which the heated thermode surface rests on the conductor, the heat from the thermode surface spreads almost exclusively in the conductor, the solder material and the conductive layer disposed therebelow. In particular, the photosensitive layer disposed under the conductive layer and the underlying conductive layer are only slightly or even no longer heated. The heat is distributed only in a small area, which depends on the contact area of the thermode, the temperature of the thermode, the contact time during which the thermode is brought into contact with the conductor, and the pressing force with which the heated thermode surface is pressed onto the conductor will, is dependent.

Thus, the temperature stress to which the conductor and the layer arrangement are exposed, lower, whereby a delamination or a breakage of the layer assembly during the soldering process can be largely avoided. Thereby, those areas of the photosensitive layer which are projected below the contact surface of the thermode and thus below the surface of the conductor can be used for voltage generation. In particular, the region of the photosensitive layer may be used to generate the charge when the light is incident, which lies under a surface of the conductive layer to which the conductor is connected to the conductive layer.

In a photovoltaic module in which a plurality of photocells are connected in a series connection and the conductor is arranged on an edge cell of the module, for example the back contact cell of the photovoltaic module, the back contact cell can be used for voltage generation, since the photosensitive layer of the back contact cell, which under the surface of the Conductor is arranged while the soldering remains intact.

According to a further embodiment of the method, the solder material may contain tin or silver and may have a melting temperature between 210 ° C and 230 ° C. The conductor may be coated on at least one side with the solder material.

The layer structure of the conductive layers and the photosensitive layer forms, together with a carrier substrate on which the layer structure is arranged, a layer arrangement of a photovoltaic module. The carrier substrate may be formed, for example, as a glass sheet. The conductor may be strip-shaped, for example as a copper-coated contact strip, which is coated on at least one side with a solder material. The conductive layer of the layer assembly may comprise a transparent conductive oxide.

According to another embodiment of the method, the temperature controlled tool is cleaned after a number of steps of pressing the temperature controlled tool on the conductor. Cleaning of the temperature controlled tool may occur after every sixtieth to eightieth step of pressing the temperature controlled tool onto the conductor. Cleaning of the temperature controlled tool may be accomplished by mechanical or chemical action on a surface of the temperature controlled tool which is pressed against the conductor during heating of the conductor.

Due to the short contact times of the thermode between 500 ms and 700 ms, the time required to make the contact between the conductive layer of a photovoltaic module and the conductor, compared to a method in which the thermode is much longer in contact with the conductor be shortened so that, for example, after every seventh step of pressing the Thermodenfläche on the head, a cleaning of the dirty Thermodenfläche can be done and still in the same period of time a geliche or even higher number of contacted modules can be made. During a cleaning cycle, for example, the thermode surface contaminated by the solder material is guided twice over a rough surface, so that the contact surface the thermode adhering solder material is rubbed off. As a result, quality fluctuations that have hitherto occurred due to soiled thermodes during a number of subsequent soldering operations can be greatly reduced, as a result of which the process of soldering the conductor to the conductive layer can be largely homogeneous. The regular cleaning of the thermode contact surface also allows the wear of the thermode to be greatly reduced.

The method makes it possible to produce a photovoltaic module in which the photocell structure, which is arranged under the contact regions of the band-shaped conductor, remains intact and can thus be used to generate charge carriers in the event of incidence of light, since the solder material melts due to the short contact time and the high temperature of the thermistor, however, the heat propagates only into the conductive layer disposed over the photosensitive layer. The photovoltaic module comprises a photocell having a photosensitive layer for generating a charge when light is incident on the photosensitive layer, a conductive layer disposed over the photosensitive layer for sensing a potential of a voltage, and a further conductive layer disposed below the photosensitive layer. Furthermore, the module comprises a conductor for contacting the conductive layer, wherein the conductor is connected to the conductive layer on a surface of the conductive layer. A portion of the photosensitive layer projected below the surface of the conductive layer generates a charge upon the incident of light on the photosensitive layer, thereby creating a voltage between the conductive layer and the further conductive layer. The conductor may, for example, be soldered to the surface of the conductive layer. The conductive layer and the further conductive layer are isolated from each other by the photosensitive layer.

The photovoltaic module may comprise further layer arrangements, each with a photosensitive layer for generating a charge upon the incidence of light on the photosensitive layer, wherein the layer arrangement and the further layer arrangements are connected to one another in a series connection.

The invention will be explained in more detail below with reference to figures showing embodiments of the invention. Show it:

1A an embodiment of a photovoltaic module with different layers of a layer arrangement,

1B an embodiment of a conductive layer for contacting a photovoltaic module,

2 an embodiment of a photovoltaic module with serially connected photosensitive layer arrangements,

3 a flow diagram of a method for contacting a photovoltaic module,

4 an embodiment of a method for contacting a photovoltaic module,

5 an embodiment of a photovoltaic module with a plurality of serially connected photosensitive layer assemblies.

1A shows a layer arrangement 100 a photovoltaic module. The layer arrangement has a substrate layer 10 on, which may be formed, for example, as a glass layer. On the substrate layer 10 is a conductive layer 20 arranged. On the conductive layer 20 is a photosensitive layer 30 arranged, the semiconducting, photoactive materials having.

In the embodiment of a tandem solar module, the photosensitive layer 30 be formed of different sub-layers. In the embodiment of 1 has the photosensitive layer 30 a partial layer 31 and a sub-layer 32 on. The sublayers are sensitive to light of different wavelengths. The sub-layer 31 may contain microcrystalline silicon and thereby becomes sensitive to light rays of the visible light spectrum having a relatively long wavelength and to portions of the light spectrum in the infrared region. The compared to the sub-layer 31 Thinner partial layer 32 is designed to convert light beams of shorter wavelength of the visible spectrum into electrical energy and may, for example, contain amorphous silicon.

Over the photosensitive layer 30 is another conductive layer 40 intended. For encapsulating the layer structure of the conductive layer 20 , the photosensitive layer 30 and the conductive layer 40 is above the conductive layer 40 a film layer 50 from a thermoplastic and a glass pane 60 intended. The layer structure of the photosensitive layer 30 and the two conductive layers 20 and 40 is thus between the two glass layers 10 and 60 encapsulated in a composite arrangement.

The conductive layer 20 , which forms a front contact of the photovoltaic module, may be formed as a light transparent layer. The conductive layer 20 can be a transparent example conductive oxide, for example tin or zinc oxide. The photosensitive layer 30 is formed as a light-absorbing layer in which free charge carriers are generated in the event of incidence of light.

The conductive layer 40 forms the backside metallization or the back contact of the module. 1B shows the conductive layer 40 in a more detailed presentation. The conductive layer 40 may include multiple layers. The conductive layer 40 For example, a layer of a transparent conductive oxide (TCO layer) 41 and have arranged above it, metallic layer layers. As the TCO (Transparent Conductive Oxide) layer layer, for example, on the photosensitive absorber layer 30 a layer of zinc oxide may be arranged on which a layer layer 42 comprising a reflective material. The reflective layer layer may comprise, for example, silver or a silver alloy. On the reflective layer layer may be a protective layer layer 43 be arranged. The protective layer layer may contain a metal, for example nickel vanadium, aluminum, molybdenum, titanium or titanium oxide. Furthermore, between the transparent conductive layer layer 41 and the reflective layer layer 42 a layered layer 44 be provided, which contains a bonding agent.

The layer layer 41 For example, the transparent conductive oxide may have a layer thickness of approximately 100 nm. The above arranged reflective layer layer 42 may have a layer thickness of about 100 nm and the protective layer layer 43 may have a layer thickness of about 50 nm. The thickness of the individual layer layers may vary slightly, so that the entire conductive layer 40 may have a layer thickness between 100 nm and 500 nm.

When light passes through the lower pane of glass 10 and the transparent conductive layer 20 the light penetrates into the photosensitive layer 30 in which free charge carriers are generated. On the conductive layers 20 and 40 Thus, opposite voltage potentials arise when the light is incident.

For contacting the conductive layer 40 is before the encapsulation of the layer structure of the photosensitive layer 30 and the conductive layers 20 and 40 an electrical conductor with the conductive layer 40 connected. So that the layer structure can be encapsulated between the two glass panes, a contact strip can be used as the conductor, on which a voltage potential can be picked up when the light-sensitive layer strikes light.

2 shows an embodiment of a photovoltaic module of photocells Z1, Z2, which are connected to each other in series, and edge cells 1 . 2 , The photocells and the marginal cells are on a carrier substrate 10 , For example, a glass layer arranged. The marginal cells may have a width D1 of, for example, 8 mm. The photocells 1 . 2 may have a width D2 of, for example, 10 mm. For contacting the series connection of the photocells, the two marginal cells 1 . 2 over a ladder 200 of the photovoltaic module with contact connections 210 connected to the module. Each individual photocell Z1, Z2 has the photosensitive layer 30 on that between the lower conductive layer 20 and the upper conductive layer 40 is arranged. The incidence of light arises between the conductive layers 20 and 40 a tension. By the series connection of the photocells becomes a charge, which at the conductive layer 20 the photocell Z1 is generated on the conductive layer 40 transmitted to the adjacent photocell Z2. For this purpose, the conductive layer passes 40 the photocell Z2 on one edge side of the photocell Z2 in the direction of the conductive layer 20 the photocell Z1. The conductive layer 40 the photocell Z2 is thus with the conductive layer 20 connected to the photocell Z1.

After making the in 2 shown layer arrangement of the series-connected cells 1 , Z1, Z2 and 2 become the two marginal cells 1 . 2 each with the conductor 200 connected. The electrical conductors 200 can be designed as contact bands, for example as band-shaped conductor made of copper. According to a possible embodiment, the conductor 200 coated on both sides with a solder material, for example with a solder material containing tin or silver. A contact page of the leader 200 may for example have a width D3 of 4 mm. The conductor may have a thickness between 100 .mu.m and 150 .mu.m and be coated with a solder material, wherein the layer thickness of the solder material may be between 10 .mu.m and 20 .mu.m. The two leaders 200 are for tapping opposite voltage potentials to the contact terminals 210 connected. To connect the conductors 200 with the respective border cells 1 . 2 a soldering process can be used.

Before the soldering process are the carrier substrate and the layers 20 . 30 and 40 the photo and border cells initially at room temperature, usually in a temperature range between 18 ° C to 25 ° C. For heating the solder material are temperature-controlled tools, such as thermodes, on the two contact strips 200 pressed. The thermodes can have a temperature of about 330 ° C. To melt the solder material, the heated thermode surfaces are pressed onto the conductor, for example for a period of approximately 1750 ms.

Due to the relatively long contact time of 1750 ms between the thermode and the conductive layer 40 The heat spreads not only in the conductive layer 40 but also in the underlying photosensitive layer 30 , the conductive layer 20 and the glass substrate 10 out. The heat over the long period of time can cause the conductive layers 20 and 40 melt. Between the conductive layers may pass through the photosensitive layer 30 form an ohmic contact through it. The soldering process thus makes it possible to short-circuit the conductive layers with one another. Because within the series circuit of the intact photocells Z1, Z2 and the edge cells 1 . 2 the diode structures of the peripheral cells are converted into an ohmic resistance by the soldering process, the photoactive surface of the photovoltaic module is reduced.

Furthermore, due to the large difference in temperature between the heated thermode surfaces and the conductor 200 and the layer arrangement of the glass layer 10 , the conductive layer 20 , the photosensitive layer 30 and the conductive layer 40 in the area of the thermode surface a large temperature stress. The temperature influence can in particular in one area 33 under the contact area of the thermode or under a surface 201 of the leader 200 at which the conductor with the conductive layer 40 is connected, lead to the delamination of the arranged in this area electrically active layers.

The delamination can be particularly at interfaces of under the backside metallization 40 applied layers, for example, at the interface between the transparent front contact layer 20 and the photosensitive layer 30 or between the photosensitive layer 30 and the conductive layer 40 respectively. Inside the conductive layer 40 may be a delamination between the individual layers of the conductive layer 40 occur. Delamination may occur at the interface between the transparent conductive oxide layer 41 , For example, the zinc oxide layer, and the reflective layer disposed above 42 , For example, the metallic layer of silver occur.

In particular, the peripheral cell forming the back contact of the photovoltaic module 1 is destroyed by shorting the diode structure arranged below the thermode surface. As a result, an increase in the photoelectrically inactive area of the solar module and a loss of the voltage generated by the module occurs, resulting in a reduced power of the photovoltaic module.

In order to prevent delamination of the layers during the soldering process, among other things, the use of adhesion-promoting layers may be necessary in order to be able to ensure a sufficiently large process window for the soldering process. For example, between the transparent conductive oxide layer of the layer 40 For example, the zinc oxide layer, and the reflective layer of the layer 40 For example, the silver layer, an adhesion-promoting layer 44 be arranged, which contains chromium. However, adhesion-promoting layers of this type can generally lead to a reduction in the optical properties of the back contact since the adhesion promoter reduces the reflectivity of the reflective layer and increased absorption takes place at the reflective layer. As a result, less radiation is absorbed into the photosensitive absorber layer 30 reflected back, whereby a reduction of the photocurrent occurs.

If the leader 200 coated on both its upper side and on its underside with solder material, arises when pressing a heated thermode surface on the coated conductor 200 on the thermode surface a deposition of the solder material. As the number of soldering operations increases, the thermode areas become more and more contaminated by the molten solder material. In order to achieve a sufficient quality of the soldering, the Thermodenflächen must be cleaned at certain intervals. In a soldering process in which the thermode surfaces are heated to about 330 ° C and are pressed onto the conductor for a period of 1750 ms, cleaning of the contaminated thermode surface can be carried out, for example, after 140 soldering operations.

Although the two marginal cells 1 . 2 also have a photosensitive layer, these two cells do not contribute to the generation of voltage. The border cell 1 is largely destroyed by the soldering process. At the border cell 2 the conductive layer passes 40 strip-shaped on one side of the edge cell in the direction of the conductive layer 20 the photocell Z2. The border cell 2 Thus, only the function has the charge that is on the conductive layer 20 the photocell Z2 has accumulated on the conductive layer 40 the border cell 2 to transport.

A further embodiment of a method for producing a photovoltaic module and the photovoltaic module produced by this method is described below with reference to FIG 3 . 4 and 5 described.

5 shows a cross section through a photovoltaic module 1000 with the marginal cells 1 and 2 and the photocells Z1, Z2. In the longitudinal direction of Photovoltaic module, the cells are formed as narrow strips, which are separated by the trench G. Each of the cells has a layer sequence of conductive layers 20 . 40 and a photosensitive layer 30 on. The cells are separated from each other by a trench G. In contrast to the embodiment of 2 are the marginal cell 1 and the photocell Z1 are not formed as a continuous layer arrangement, but are separated from each other by the trench G. The border cell 1 , which forms the back contact cell of the photovoltaic module, is through the conductor 200 and a connection line 220 with the contact connection 210 connected. The border cell 2 is by the other leader 200 and the other connection conductor 220 with another contact connection 210 connected. The leader 200 may be a band-shaped conductor. For example, a contact tape containing a material of copper may be used.

For the production of the photovoltaic module 1000 First, the electrically conductive layer 20 as a continuous layer on a carrier substrate 10 , For example, a glass substrate, arranged. The glass substrate may, for example, have a thickness of 3 mm. The conductive layer 20 can by a deposition process with a thickness of 2 microns on the glass substrate layer 10 be deposited. The conductive layer 20 can as a front contact of the photovoltaic module 1000 be transparent and contain a transparent conductive oxide, for example, a material of tin oxide.

For separation or isolation of the first continuous on the carrier substrate, continuously arranged conductive layer 20 In a subsequent process step, trenches, for example by a laser process, are introduced into the conductive layer 20 brought in. This results in individual electrically isolated conductive layers 20 , In a next process step, the photosensitive layer, for example a layer containing silicon, is deposited over the discontinuous conductive layers 20 arranged. In a subsequent process, the initially still continuously arranged photosensitive layer is separated by trenches, so that on each of a conductive layer 20 a photo / border cell an isolated photosensitive layer 30 is available. In a further process step, a conductive layer is formed over the photosensitive layer 40 , For example, by sputtering, arranged.

First, the material is the conductive layer 40 also present in the trenches between the photosensitive layers arranged separately from each other. In a subsequent process step, the individual photocells are separated from each other by again trenches G, are introduced into the areas in which the conductive layer 40 with the conductive layer 20 in contact. The trenches can, for example, by a laser process in the conductive layer 40 be introduced. The trenches are thereby introduced between the cells, that of the peripheral cell 2 and the photocells Z1, Z2 each have a narrow strip of material of the conductive layer 40 the conductive layer 40 with the conductive layer 20 the adjacent cell connects. Thus, the individual cells 1 , Z1, Z2 and 2 connected in series.

For contacting the series-connected photocells of the photovoltaic module with the conductors 200 a soldering process is used in which the marginal cells 1 and 2 each with a ladder 200 get connected. The leader 200 may be formed as a band-shaped conductor, for example, a contact band, the at least on one side 201 with a solder material 300 is coated. It can also be used a contact band, the two-sided, on the side 201 and the opposite side 202 coated with the solder material. The solder material may contain a mixture of a material of tin or silver.

The individual process steps F1,..., F5 of the contacting process, in each case one contact band 200 with one of the marginal cells 1 . 2 are contacted in 3 shown.

In a manufacturing step F1, the layer arrangement of the conductive layer 20 , the photosensitive layer 30 and the conductive layer disposed above 40 produced. This results in the cell structures connected in series 1 , Z1, Z2 and 2 of the 5 , which are separated from each other by the trench G.

In a production step F2 becomes a conductor 200 on one of the two marginal cells 1 and 2 arranged. The conductor may be band-shaped. Between the conductor 200 and the conductive layer 40 a solder material is arranged. This can be done by at least one side of the band-shaped conductor, for example, the lower side 201 of the leader 200 coated with a solder material. It can also be a leader 200 be used, where both sides 201 . 202 coated with a solder material.

In a subsequent production step F3, a temperature-controlled tool, for example a thermode, is heated to a temperature which lies between 150 ° C. and 190 ° C. above the melting temperature of the solder material. For example, if a solder material having a melting temperature of about 221 ° C is used, the thermode may be heated to a temperature between 370 ° C and 410 ° C. Preferably, the Surface, with which the thermode is pressed onto the conductor, heated to a temperature of 390 ° C.

A subsequent production step F4 is in 4 shown. 4 shows a section of a side view of the in 5 shown in cross-section photovoltaic module. The cells 1 , Z1, Z2 and 2 are designed as narrow strips in the longitudinal direction of the module. In 4 is a section of the border cell 1 or the border cell 2 shown in the longitudinal direction of the photovoltaic module. The leader 200 For example, on the areas 31 and 32 with the conductor 200 be soldered. For this purpose, respective contact surfaces 501 the thermodes 500 at the areas 31 and 32 on the ladder 200 pressed. The contact areas 31 and 32 For example, they may have a spacing between 30 μm and 35 μm. The pressure force with which the thermode surfaces 501 the thermodes are pressed onto the conductor is between 10 N and 40 N. The contact surfaces of the thermodes are heated to a temperature between 150 ° C and 190 ° C above the melting temperature of the solder material 300 lies. The thermodes are pressed onto the conductor for a period between 500 ms and 700 ms.

The leader 200 may have a thickness of 100 microns to 150 microns. In the case of using a conductor coated with the solder material, the solder material may have a thickness between 10 μm and 15 μm. In particular, when using such a conductor and a layer thickness of the conductive layer 40 of 100 nm to 500 nm, in particular a transparent conductive oxide layer of about 100 nm, a reflective layer of about 100 nm and a protective layer layer of about 50 nm, and a solder material, the Having tin or silver and has a melting point between 210 ° C and 230 ° C, a temperature of the thermodes of about 390 ° C has been found to be sufficient for the solder material melts within the period of 500 ms to 700 ms.

Due to the short contact time between 500 ms and 700 ms, the thermal temperature between 150 ° C and 190 ° C above the melting point of the solder material and a pressure force of the thermodes between 10 N and 40 N is achieved that the heat of the thermodes substantially only the contact areas B1 and B2 in the conductor 200 , in the soldering material 300 and in the conductive layer 40 spreads. The supplied heat is sufficient to allow the solder material to a surface 41 the conductive layer 40 melts. In particular, however, the melting of the conductive layers 30 and 40 be prevented, whereby, for example, the formation of conductive silicides, such as silver silicides can be prevented, the front contact 20 and the back contact 40 connect through the diode structure through an ohmic contact. The selected process parameters for the soldering process ensure that the heat does not reach the photosensitive layer 30 spreads. As a result, the temperature stress during the soldering process can be reduced, whereby destruction of the electrically active layers upon incident light can be prevented.

The high temperature of the thermodes allows on the one hand, that the solder material between the conductor 200 and the upper conductive layer 40 is arranged, melts. On the other hand, the short contact time ensures damage to the layers 20 . 30 and 40 the layer structure arranged on the substrate layer, in particular a delamination of these layers, is avoided. Thereby, the photosensitive layer disposed in an area under the contact area B1, B2 can be used to generate carriers in the incident light.

When using the short process times has proven advantageous that temperature gradients between the contact strip 200 and the substrate layer 10 within the period of 500 ms to 700 ms do not lead to a cooling, which would have to be compensated by an additional energy input. The total energy that is introduced into the soldering process is at least a factor of 2 less than in a method in which the thermodes are heated to a temperature of about 330 ° C and for a period of about 1750 ms on the conductor 200 be pressed on.

After melting the solder material, the heated areas B1 and B2 are cooled in a production step F5, whereby the solder material solidifies. For this example, air at room temperature can be blown onto the solder joint until the solder material is solidified. After solidification of the soldering material is the conductor 200 on the surfaces 41 the conductive layer 40 with the conductive layer 40 connected.

Reducing the contact time of the thermode area from 1750 ms to 500 ms to 700 ms allows the thermode areas contaminated by the molten solder material to be cleaned more frequently while still reducing the number of modules produced per unit of time, the so-called throughput Photovoltaic modules compared to a process in which the contact times of the thermodes are more than 1500 ms, can be increased. The cleaning of the thermode surfaces can be done chemically or physically. For example, during mechanical cleaning, the thermode surfaces are moved over a rough surface, thereby abrading the solder material adhering to the thermode surface. Shortening the contact times to a time between 500 ms and 700 ms makes it possible to perform a cleaning cycle after approximately sixty to eighty soldering operations. In such a cleaning step, for example, the contact surfaces of the thermodes are moved over a rough surface twice to remove the solder material from the contact surface.

Since a cleaning process for cleaning the thermode, for example, already carried out after every 70 soldering operations, the soldering process is much more stable than if the thermodes are cleaned only after every 140 soldering processes. This also increases the service life or the life of the thermodes.

As in the embodiments of the photovoltaic modules of 2 and 5 is shown, the edge cell 1 in projection under a surface 41 the conductive layer 40 an area 33 from the photosensitive layer 30 and the conductive layers 20 and 40 on. In contrast to the method for producing the photovoltaic module of 2 in which an area 33 the layer arrangement is destroyed under the solder joint, be in the process for producing the photovoltaic module of the 5 , the areas arranged under the solder joint 33 the conductive layers 20 and 40 and the photosensitive layer 30 not destroyed due to the lower temperature stress. In particular, a delamination between the layers 20 . 30 . 40 and between the layers of the layer 40 be prevented.

Thus, the area 33 the photosensitive layer 30 that under the contact surface 41 the conductive layer 40 is to be used for voltage generation. This has the consequence that the complete marginal cell 1 , which corresponds to the back contact cell of the photovoltaic module, can be used as a photocell for generating voltage. The peripheral cell is therefore formed such that the conductive layer 40 the back contact cell 1 through the photosensitive layer 30 from the conductive layer 20 is isolated. Because the conductive layers 30 and 40 not connected by ohmic contact, carries the entire photosensitive layer 30 the border cell 1 for the generation of charge carriers.

As a delamination of the layers of the conductive layer 40 is prevented by the reduced thermal stress, the use of adhesion-promoting layers, which have previously caused a reduction of the photocurrent, no longer required. In particular, the adhesion-promoting layer layer 44 between the conductive transparent oxide layer layer 41 and the reflective layer layer 42 the layer 40 omitted. The reflective layer layer 42 can thus directly above the conductive transparent oxide layer 41 to be ordered. As a result, absorption of light radiation at the reflective layer is avoided and the efficiency of the photocell is increased.

In the embodiment of the photovoltaic module according to 5 can be used for land vehicle generation, undamaged border cell 1 a width D2, for example, 10 mm, which corresponds to the width D2 of the remaining photocells. If the marginal cell 1 has the same width as the other photocells, a current limitation in the series connection of the photocells can be avoided. The border cell 2 , which serves only as a contact, compared to the other cells Z1, Z2 and 1 be made with a reduced width D4, for example, a width of 6 mm.

LIST OF REFERENCE NUMBERS

10

carrier substrate

20

conductive layer

30

photosensitive layer

40

conductive layer

41

contact area

50

film material

60

carrier substrate

100

layer arrangement

200

electrical conductor

210

Contact Termination

220

connecting conductors

300

solder

500

thermode

1000

photovoltaic module

Claims (14)

Method for contacting a photovoltaic module, comprising: providing a layer arrangement ( 100 ) from a photosensitive layer ( 30 ) for generating a charge upon the incident of light on the photosensitive layer and on the photosensitive layer (US Pat. 30 ) arranged conductive layer ( 40 ) for picking up a voltage, - providing a conductor ( 200 ) for contacting the conductive layer ( 40 ), - providing a soldering material ( 300 ) for soldering the conductor ( 200 ) on the conductive layer ( 40 ), - arranging the conductor ( 200 ) and the soldering material ( 300 ) on the layer arrangement ( 100 ) such that between the conductive layer ( 40 ) and the leader ( 200 ) the solder material ( 300 ), - arranging a temperature-controlled tool on the conductor ( 200 ) for heating the conductor ( 200 ), wherein the temperature-controlled tool is heated to a temperature which is between 150 ° C and 190 ° C above the melting temperature of the solder material, - melting the solder material ( 300 ), - cooling and solidification of the solder material ( 300 ) - connecting the conductor ( 200 ) with the conductive layer ( 40 ). Method according to claim 1, wherein the solder material ( 300 ) Contains tin or silver and has a melting temperature between 210 ° C and 230 ° C. Method according to claim 1 or 2, wherein the conductor ( 200 ) on at least one side ( 201 ) with the solder material ( 300 ) is coated. Method according to one of claims 1 to 3, wherein the temperature-controlled tool for a period of time between 500 ms and 700 ms on the conductor ( 200 ) is pressed. Method according to claim 4, wherein the temperature-controlled tool ( 500 ) with a pressure force between 10 N to 40 N on the conductor ( 200 ) is pressed. Method according to one of claims 4 or 5, wherein the temperature-controlled tool ( 500 ) to a temperature between 370 ° C and 410 ° C, in particular to a temperature of 390 ° C, is heated. Method according to one of claims 1 to 6, wherein the conductive layer ( 40 ) of the layer arrangement comprises a transparent conductive oxide. Method according to one of claims 1 to 7, comprising: cleaning the temperature-controlled tool ( 500 ) after a number of steps of applying the temperature controlled tool to the conductor ( 200 ). Method according to claim 8, wherein the cleaning of the temperature-controlled tool ( 500 ) after every sixtieth to eightieth step of pressing the temperature controlled tool onto the conductor ( 200 ) he follows. Method according to one of claims 8 or 9, comprising: cleaning the temperature-controlled tool ( 500 ) by mechanical or chemical action on a surface ( 501 ) of the temperature-controlled tool ( 500 ), which during the heating of the conductor ( 200 ) on the ladder ( 200 ) is pressed. Photovoltaic module, comprising: - a photocell ( 1 ) with a photosensitive layer ( 30 ) for generating a charge upon the incident of light on the photosensitive layer, one above the photosensitive layer ( 30 ) arranged conductive layer ( 40 ) for sensing a potential of a voltage and a voltage below the photosensitive layer ( 30 ) arranged further conductive layer ( 20 ), - a ladder ( 200 ) for contacting the conductive layer ( 40 ), - the leader ( 200 ) on an area ( 41 ) of the conductive layer ( 40 ) with the conductive layer ( 40 ) - where one area ( 33 ) of the photosensitive layer ( 30 ) projected below the surface ( 41 ) of the conductive layer is arranged upon the incidence of light on the photosensitive layer ( 30 ) generates a charge, whereby between the conductive layer ( 40 ) and the further conductive layer ( 20 ) creates a tension. A photovoltaic module according to claim 11, wherein between the conductive layer ( 20 ) and the further conductive layer ( 40 ) no ohmic contact is formed. Photovoltaic module according to one of claims 11 or 12, wherein the conductor is applied to the surface ( 41 ) of the conductive layer ( 40 ) is soldered. Photovoltaic module according to one of claims 11 to 13, comprising: - further photocells (Z1, Z2) each having a photosensitive layer ( 10 ) for generating a charge upon the incidence of light on the photosensitive layer, - wherein the photocell ( 1 ) and the further photocells (Z1, Z2) are connected to each other in a series circuit.

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