DE102011051470A1 - Method for interconnecting thin layer solar module, involves positioning contact strip on contact module of solar module such that conductive adhesive layer is attached with contact module for providing electrical connection - Google Patents

Abstract

The method involves providing a contact strip (1) with a band-shaped metal film (11) stretching in a longitudinal direction (L). A conductive adhesive layer (13) is formed on a bottom side of the metal film and a covering layer (12) is formed on an upper side of the metal film. A solar module is provided with a contact module which is electrically connected with a solar cell. The contact strip is positioned on the contact module of solar module such that the conductive adhesive layer is attached with the contact module for providing electrical connection. An independent claim is included for a contact strip.

Description

The invention relates to a method for interconnecting a solar module and to a contact strip.

In solar modules, in particular thin-film solar modules, interconnecting the solar cells with an external load to remove the generated current is an important issue. As a rule, the solar cells of a solar module are interconnected on a monolithic level, wherein the solar cells are connected at the outer ends or at the edge regions of the solar module via electrical connectors to a junction box.

These electrical connectors usually consist of a strip of metal foil, which is connected by means of a conductive adhesive with a metal contact of the corresponding solar cell. So that the electrical connector does not cause a short circuit, an insulating tape is placed over the strip of metal foil, usually in such a way that the entire metal contact of the solar cell is also protected and covered. The structure resulting from this prior art process is described in US Pat 1 illustrated and explained in more detail below.

The above-described method for interconnecting the solar module comprises a plurality of steps in which the adhesive, the metal strip and the insulating tape are applied to the solar cell. Each step requires adjustment processes, which can be time consuming and a source of errors that can lead to higher costs. Since the adjustment of the three layers of adhesive, metal strip and insulating tape to each other and in particular with respect to the metal contact of the solar cell must be done with certain tolerances, are lost in this method, parts of the module substrate.

The underlying object of the invention is to provide a method and a contact strip for interconnecting a solar module, in particular a thin-film solar module, while reducing the tolerance requirements in connection with the adjustment and positioning of the contact strip on the solar module.

This object is achieved according to the invention by a method for interconnecting a solar module with the features of claim 1 and by a contact strip with the features of claim 6. Further advantageous embodiments of the invention are described in the dependent claims.

The invention is based on the idea of providing the metal layer used to interconnect the solar module with a conductive adhesive layer on one side and a cover layer on the other side to form the contact ribbon. In other words, the contact band already comprises both the adhesive layer for attaching the metal layer to a module contact of the solar module and the insulating cover layer for protecting the metal layer from the effects of the weather and for preventing short-circuits. It should be noted that novelty of the contact strip in comparison to the prior art described above is in particular in that the three-layer contact strip is suitable for connection to a solar module contact. Therefore, it is not yet connected to the module contact, but rolled up, for example, to a roll of tape.

Since the adhesive and the cover are already connected to the metal layer of the contact strip, fewer steps are required to produce the solar module. Furthermore, no complicated adjustments of the three layers in relation to each other are required.

The contact strip is stretched in a longitudinal direction, for example in the form of a longitudinally extending strip. The method for interconnecting the solar module includes attaching such a contact strip to the module contact, in particular to a contact region of the solar cell in the solar module structure by arranging the adhesive layer on this contact region. The adhesion of the adhesive layer to the contact area can be assisted by application of pressure and / or heat.

The contact strip may further comprise two different sections along its longitudinal direction or span direction, namely a covered section and an exposed section. In the covered portion, the contact tape comprises the above-described three layers, in the exposed portion the adhesive layer and the cover layer are either removed from the metal layer or absent from the beginning, exposing in this section the metal layer on both sides.

In an advantageous embodiment, the positioning of the contact strip on the module contact comprises positioning a first covered section in which the metal layer is covered by the conductive adhesive layer and the cover layer on a first module contact and then positioning a second covered section on a second module contact with opposite Polarity to the first module contact in the solar module, wherein the exposed portion of the Contact strip between the first and the second covered portion is arranged. The metal layer may then be cut at the exposed portion to electrically separate the first and second module contacts.

In an advantageous embodiment, positioning the contact strip on the module contact comprises positioning a first covered section in which the metal layer is covered by the conductive adhesive layer and the cover layer along a first edge region of the solar module and positioning a second covered section along a second edge region of the solar module Solar module opposite the first edge region, wherein the exposed portion of the contact strip between the first and the second covered portion is arranged. The solar cells arranged between the first and the second side region can be connected in series with one another.

In both cases, after attaching the contact strip to the module contact, the metal layer may be cut transversely to the longitudinal direction in the exposed portion, which is not connected to the module contact due to the lack of an adhesive layer. The cutting across the longitudinal direction can be done at right angles or almost at right angles. Or it can be done at a different angle to the longitudinal direction. The cutting of the contact strip in the exposed portion leads to separate two ends of the contact strip, which can form two terminal terminals of the solar module and have an opposite polarity.

In an advantageous embodiment, the cover layer of the contact strip has a width perpendicular to the longitudinal direction and perpendicular to the thickness of the cover layer which is at most 30, 20, 10 or 5% greater than the width of the metal layer. Advantageously, the width of the cover layer is substantially equal to the width of the metal layer. Since any adjustment of the three layers of the contact strip can be dispensed with and the cover layer and / or the adhesive layer can be attached to the metal layer with high accuracy during the production of the contact strip, the cover layer can have a very small width without unintentionally exposing the metal layer , Likewise, the adhesive layer may have a width which is at most 30%, 20%, 10% or 5% larger or smaller than the width of the metal layer. As with the cover layer, the width of the adhesive layer may be substantially equal to the width of the metal layer.

In an advantageous embodiment, the cover layer is a lacquer layer which is applied or vapor-deposited onto the metal layer. This layer may have a thickness in a range between 5 and 100 microns. Even thicker layers are possible to achieve better insulation, provided that a suitable lacquer is used. Alternatively, or additionally, the cover layer may comprise a tape attached to the metal layer or lacquer layer. In this case, the layer thickness of the cover layer can be, for example, between 25 and 200 μm.

In an advantageous embodiment, the conductive adhesive layer comprises a material having a contact resistance of less than 10 ohm cm ² , preferably less than 0.2 ohm cm ² . The adhesive material used can be a conductive polymer, for example an epoxide which preferably comprises metal particles, in particular silver particles, and / or carbon fiber particles in order to achieve the required conductivity.

In an advantageous embodiment, the exposed portion of the contact strip in the longitudinal direction has a length of more than 1, 2, 5, 10 or 20 mm. Depending on the size of the solar module and the position of the junction box, the length of the exposed portion may be greater, for example 60, 80, 100 or about 120 cm.

In an advantageous embodiment, the cover layer of the contact strip is attached to the metal layer by means of a further adhesive layer. This adhesive layer should ideally not be conductive.

Some embodiments of the invention will be explained in more detail below with reference to the accompanying schematic drawings. Hereby show:

1 a cross-sectional view of an edge region of a solar module according to the prior art;

2 a cross-sectional view of an edge region of a solar module with a contact strip according to an embodiment of the invention;

3 a cross-sectional view of a contact strip along a longitudinal direction;

4 the process of cutting the contact strip 3 at an exposed section; and

5 a schematic perspective view of a solar module with attached along edge regions contact bands.

The cross section of a border area 20 of a solar module according to the prior art is in 1 shown schematically. Therein is a module substrate 22 pictured on which a solar cell 23 is formed, wherein the solar cell 23 a substrate-side solar cell contact, which at the same time a module contact 21 is, an optically active layer 24 and an upper contact layer 25 includes.

A contact element in the form of a metal strip 31 becomes with the module contact 21 connected by first a conductive adhesive strip 33 at the module contact 21 attached and the metal strip 31 then on adhesive strips 33 is arranged. The metal strip 31 and indeed the entire exposed section of the module contact 21 that is not from the active layer 24 the solar cell 23 is covered with insulating tape 32 covered. As in 1 is also part of the active layer 24 the solar cell 23 even with the insulating tape 32 covered, causing this part of the active layer 24 is wasted. Additionally, the exposed portion of the module contact must be 21 that is not through the active layer 24 covered, be very wide enough to accommodate the position of the metal strip 31 in relation to the adhesive strip 33 letting it, leaving room on the module substrate 22 that could otherwise have been used to generate electricity.

2 shows a cross section of a border area 20 a solar module with a contact ribbon 1 is connected, according to an embodiment of the invention. The solar module comprises a module substrate 22 on the solar cells 23 are formed. Every solar cell 23 includes a substrate-side solar cell contact, an active layer 24 and an upper contact layer 25 , The active layer 24 may include the elements copper, indium, gallium, and selenium to form a so-called CIGS solar cell. The upper contact layer 25 is preferably formed of a transparent conductive material, for example, an aluminum-doped zinc oxide.

The substrate-side solar cell contact of the solar cell 23 also forms the module contact 21 which is preferably formed of a metal such as molybdenum and having a covered portion 12 of the contact band 1 is connected. In this covered section 14 includes the contact ribbon 1 a metal layer 11 between a conductive adhesive layer 13 They contact the module contact 21 attaches, and a topcoat 12 stacked, which protects their otherwise exposed surface. In the in 2 illustrated embodiment, have the cover layer 12 and the conductive adhesive layer 13 of the contact band 1 essentially the same width as the metal layer 11 , Since no greater clearance is required, the width of the exposed portion of the module contact 21 that is not through the active layer 24 is covered, thereby minimizing a larger area of the module substrate 22 from the active layer 24 the solar cells 23 can be covered, as in 2 shown.

The composition of a contact ribbon 1 According to an advantageous embodiment is in 3 shown in a schematic cross-sectional view. The contact ribbon 1 is stretched in the longitudinal direction L, represented by the two-sided arrow in FIG 3 , It covers a covered section 14 in which the metal layer 11 of the contact band 1 is covered on both sides, namely by means of Leitkleberschicht 13 on the one and the top layer 12 on the other hand. In addition, the contact strip includes 1 an exposed section 10 in which the metal layer 11 exposed on both sides. Preferably, the contact band comprises 1 a plurality of exposed portions distributed along the longitudinal direction L. 10 , Preferably, the distribution of the exposed portions 10 along the longitudinal direction L equidistant. Advantageously, the contact band 1 wound into a tape reel.

As in 4 shown, the contact strip 1 on the exposed sections 10 cut (represented by the scissors symbol) to two separate contact strips 1 to receive, each a covered section 14 and an exposed section 10 include. The arrangement of the contact ribbon 1 on the module contact 21 can be automated.

The cutting of the contact ribbon 1 on the exposed sections 10 can after attaching the contact strip 1 on a solar module 2 done as in 5 shown. 5 shows a schematic perspective view of a solar module 2 with a first edge area 201 and a second border area 202 , at each of which a module contact 21 is formed. Each of the two module contacts 21 is an electrical pole of the solar module 2 , The contact ribbon 1 is positioned on the solar panel so that a covered section 14 at the first edge area 201 is attached and another covered section 14 at the second edge area 201 on the opposite side of the solar module 2 is attached. The contact ribbon 1 has an exposed section 10 on, then in two separate exposed sections 10 is cut to the module contact 21 at the first edge area 201 from module contact 21 at the second edge area 202 to disconnect electrically.

LIST OF REFERENCE NUMBERS

1

contact strips

10

Exposed section

11

metal layer

12

topcoat

13

Leitkleberschicht

14

Covered section

2

solar module

20

border area

201

First edge area

202

Second edge area

21

Contact module

22

module substrate

23

solar cell

24

Active layer of the solar cell

25

Upper contact layer of the solar cell

31

metal strips

32

electrical tape

33

tape

L

longitudinal direction

Claims (12)

Method for interconnecting a solar module ( 2 ), comprising the following steps: - providing a contact strip ( 1 ) comprising a band-shaped metal layer ( 11 ), which is stretched in the longitudinal direction (L), a Leitkleberschicht ( 13 ) on a lower side of the metal layer ( 11 ) and a cover layer ( 12 ) on an upper side of the metal layer ( 11 ); - Provision of a solar module ( 2 ) comprising a module contact ( 21 ), which is connected to one or more solar cells of the solar module ( 2 ) is electrically connected and - positioning of the contact strip ( 1 ) on the module contact ( 21 ) of the solar module ( 2 ) such that the conductive adhesive layer ( 13 ) on the module contact ( 21 ) and an electrical connection is made. Method according to claim 1, characterized in that the contact strip ( 1 ) an exposed section ( 10 ), which extends along the longitudinal direction (L) of the metal layer ( 11 ), wherein the metal layer ( 11 ) along the exposed section ( 10 ) is exposed on both sides. Method according to claim 1 or 2, characterized in that the positioning of the contact strip ( 1 ) on the module contact ( 21 ) a positioning of a first covered section ( 14 ), in which the metal layer ( 11 ) through the conductive adhesive layer ( 13 ) and the top layer ( 12 ) on a first module contact ( 21 ) and a subsequent positioning of a second covered section ( 14 ) on a second module contact of opposite polarity to the first module contact ( 21 ) in the solar module ( 2 ), the exposed portion ( 10 ) of the contact strip ( 1 ) between the first and second covered sections ( 14 ) is arranged. Method according to one of the preceding claims, characterized in that the positioning of the contact strip ( 1 ) on the module contact ( 21 ) a positioning of a first covered section ( 14 ), in which the metal layer ( 11 ) through the conductive adhesive layer ( 13 ) and the top layer ( 12 ) is covered along a first edge region ( 201 ) of the solar module ( 2 ) and a positioning of a second covered section ( 14 ) along a second edge region ( 202 ) of the solar module ( 2 ) opposite the first edge area ( 201 ), the exposed portion ( 10 ) of the contact strip ( 1 ) between the first and second covered sections ( 14 ) is arranged. A method according to claim 3 or 4, characterized by a severing of the contact strip ( 1 ) in the exposed section ( 10 ) between the first and second covered sections ( 14 ) after positioning the contact strip ( 1 ) on the module contact ( 21 ). Contact Ribbon ( 1 ) suitable for attachment to a module contact ( 21 ) of a solar module ( 2 ), comprising a band-shaped metal layer ( 11 ), which is stretched in the longitudinal direction (L), a Leitleberschicht ( 13 ) on a lower side of the metal layer ( 11 ), suitable for adhering to the module contact ( 21 ) of the solar module ( 2 ), so that an electrical connection between the metal layer ( 11 ) and the module contact ( 21 ), a topcoat ( 12 ) on an upper side of the metal layer ( 11 ) and an exposed section ( 10 ), which extends along the longitudinal direction (L) of the metal layer ( 11 ), wherein the metal layer ( 11 ) along the exposed section ( 10 ) is exposed on both sides. Contact Ribbon ( 1 ) according to claim 6, characterized in that the cover layer ( 16 ) a width perpendicular to the longitudinal direction (L) and perpendicular to the thickness of the cover layer ( 12 ) which is at most 30%, 20%, 10% or 5% larger than the width of the metal layer. Contact Ribbon ( 1 ) according to claim 6 or 7, characterized in that the cover layer ( 12 ) is a lacquer layer, which on the metal layer ( 11 ) is applied or vapor-deposited. Contact Ribbon ( 1 ) according to claim 6 or 7, characterized in that the cover layer ( 12 ) comprises a tape which is applied to the metal layer ( 11 ) is applied. Contact Ribbon ( 1 ) according to one of claims 6 to 9, characterized in that the conductive adhesive layer ( 13 ) made of a material with a Contact resistance of less than 10 ohm cm ² , preferably less than 0.2 ohm cm ^{2 is} formed. Contact Ribbon ( 1 ) according to one of claims 6 to 10, characterized in that the exposed portion ( 10 ) in the longitudinal direction (L) has a length of more than 1, 2, 5, 10 or 20 mm. Contact Ribbon ( 1 ) according to one of claims 6 to 11, characterized in that the cover layer ( 13 ) by means of a further adhesive layer on the metal layer ( 11 ) is attached.

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