WO2016063244A1

WO2016063244A1 - Interconnecting device and method

Info

Publication number: WO2016063244A1
Application number: PCT/IB2015/058155
Authority: WO
Inventors: Wlodzimierz BLASZCZAK
Original assignee: Somont Gmbh
Priority date: 2014-10-24
Filing date: 2015-10-22
Publication date: 2016-04-28

Abstract

The invention also relates to an interconnecting device (1) for electrically interconnecting end portions of longitudinal connectors (4) of at least one string (3) of solar cells (2) by means of cross connector (5), comprising: - first transporting means (10) adapted to transport at least one string (3), preferably multiple strings (3) arranged one after another, in a first transporting direction (11), with a first transporting velocity and with the longitudinal extension of the at least one string (3) being essentially perpendicular to the first transporting direction (11); - at least one feeding station (6) for feeding cross connector (5) to the end portions of longitudinal connectors (4).

Description

Interconnecting device and method

The invention refers to an interconnecting device and interconnecting method for electrically interconnecting at least one end portion of at least one longitudinal connector of at least one solar cell string to a cross connector, the longitudinal connector preferably extending essentially in longitudinal direction of the string.

US2007079862A1 discloses a method of interconnecting individual solar cells to form a longitudinal string. Individual solar cells are electrically connected with each other by interconnectors which are soldered to the solar cells. The producing apparatus has a positioning belt and a heating belt adjacent to each other such that solar cells can be delivered between the belts. The apparatus also has a pressing belt opposite the positioning belt and the heating belt, the pressing belt being provided so as to straddle the positioning belt and the heating belt. The

interconnectors are soldered to the solar battery cells while transporting the solar battery cells and the interconnectors. The transporting direction is parallel to the longitudinal extension of the resulting string.

US2008061111A1 relates to interconnecting individual solar cells to form a longitudinal string. A solar cell fabrication apparatus including a lower belt carrying a solar cell main body and tab lead to convey the same, and an upper belt pressing the same are disclosed. A phosphor bronze plate is provided to apply an urging force against upper belts towards the lower belt. A plurality of lower heater blocks and upper heater blocks are provided to heat the solar cell main body and tab lead from below and above, respectively. As in US2007079862A1 the transporting direction of the belt is parallel to the longitudinal extension of the resulting string.

Both documents disclose the production of strings of solar cells. However, they do not disclose how to interconnect the longitudinal interconnectors (extending in longitudinal direction of the string) by means of cross connectors (mainly perpendicular to the longitudinal direction of the string).

It is known to use inductive soldering to connect ribbons to solar cells. This is e.g. known from applications like US4685608A, DE102005036130A1 , DE

102010047678A1 , DE10335438B4. Longitudinal interconnectors (also called: ribbons) electrically connect the solar cells of a string and extend in longitudinal direction of the string. They normally interconnect (only) adjacent solar cells. The longitudinal interconnectors usually extend beyond both ends of the string. In order to form a solar cell matrix, multiple strings have to be arranged one after another and electrically interconnected This is done by cross connectors, which are welded or soldered to the end portions of the longitudinal connectors as to electrically connect at least two longitudinal connectors.

According to prior art multiple strings are arranged next to each other and a cross connector is soldered to the end portions of longitudinal connectors (the end portions protruding from the two end cells of the respective string). The

interconnecting procedure may be done by hand, which is costly and time- consuming. Also manual soldering is not esthetical pleasing. Failures due to non- reproducible procedures results in deficiencies of overall quality and low throughput yield.

It is also known to use large, costly robots with multiple axis to place the cross connectors on the end portions of longitudinal connectors. In addition multiple soldering heads are required to speed up the soldering process. However, the processing speed remains limited. The strings remain stationary during the soldering process.

The object of the invention is to overcome these problems and to provide a reliable solution for electrically interconnecting at least one end portion of at least one longitudinal connector of at least one solar cell string to a cross connector. The interconnecting device and method shall be cost-effective and time-saving. The interconnecting device shall have a place-saving construction.

This object is achieved with a interconnecting device as mentioned at the beginning wherein the interconnecting device comprises: first transporting means adapted to transport at least one string, preferably multiple strings arranged one after another, in a first transporting direction and with a first transporting speed wherein preferably the first transporting means is a conveyor belt; at least one feeding station for feeding cross connector to the at least one end portion of the longitudinal connector; at least one interconnecting station (arranged downstream of the feeding station), preferably a welding or soldering station, for electrically interconnecting the at least one end portion of longitudinal connector with cross connector; at least one pressing means for pressing cross connector and end portion of the longitudinal connector against each other, wherein at least a portion of the pressing means extends in the working area of the interconnecting station; wherein the working area of the interconnecting station and the pressing zone of the pressing means extend laterally along the transport path of the strings on the first transporting means and/or in a lateral region of the first transporting means. I.e. the first transporting means defines the transport path of the strings. Preferably, the strings are transported essentially in the horizontal plane.

The first transporting means is capable to transport the string(s) with the longitudinal extension of the at least one string being essentially perpendicular to the first transporting direction. The first transporting means may be e.g. a conveyor belt and transports the string towards the feeding station. Here, the cross connectors are placed on the end portions of the longitudinal connectors to be electrically connected. With the inventive solution the placing of the cross connectors on the end portions of the longitudinal connectors can be done without stopping the first transporting means, i.e. the strings are continuously moved, preferably at an essentially constant speed. Alternatively the strings may be stopped during soldering, but this would decrease throughput.

With the invention it is possible to interconnect the longitudinal connector(s) with a cross connector in a time-saving working process and without stopping or even slowing down the transport movement of the strings on the first transporting means. The interconnecting process in the interconnecting station may be thus performed during movement of the strings. With other words: the strings are moved (by the first transporting means) along or pass the interconnecting station, without stopping. While the longitudinal connectors extend along the longitudinal extension of the strings, the cross connectors usually extend essentially perpendicular to the longitudinal connector in the assembled solar cell matrix. Thus in the feeding station, the cross connectors are brought in an orientation perpendicular to the longitudinal connectors. Orientation and/or placing of cross connectors may be done manually. In this case the feeding station is a workplace for workers. However, in a preferred embodiment feeding is done automatically by means of a feeding device, as will be discussed later in more detail.

The cross connectors may be placed on the longitudinal connectors from the side, i.e. they may be transported in a direction essentially parallel to the longitudinal connectors. In alternative embodiments they may be also transported transversely to the longitudinal connectors. Any other feeding or transporting direction would be possible.

Referring to the pressing means and the interconnecting station it is mentioned, that the working area and pressing zone extend laterally along the transport path of the strings. However, other parts of the pressing means and the interconnecting station (e.g. drives, voltage/current sources, mechanical supports) may of course extend somewhere else, e.g. above or below the transport path. The pressing zone is that area, in which the longitudinal connector and cross connector are subjected to a pressing force, pressing them together. The working area of the interconnecting station is that area where the longitudinal connector and cross connector are at least partially joined, they are e.g. heated. Preferably, the working area of the

interconnecting station and the pressing zone of the pressing means are spatially restricted to at least one area extending laterally of the transport path of the strings on the first transporting means, i.e. the working area and the pressing zone do not extend in an area overlapping with the solar cells of the strings when transported by the first transporting means along interconnecting station and pressing means.

Preferably, the working area of the interconnecting station and the pressing zone of the pressing means overlap at least partially.

It is also possible that the pressing means is part of the interconnecting station, e.g. part of the welding or soldering device. It would be e.g. possible that the

welding/soldering head presses (as pressing means) against the connectors to be interconnected. The width of the transport path of the strings on the first transporting means may be also smaller than the width of the first transporting means itself, e.g. the width of a conveyor belt. In such an embodiment the working area of the interconnecting station and the pressing zone of the pressing means may overlap with the first transporting means.

In an embodiment of the invention the working area of the interconnecting station and/or the pressing zone of the pressing means do not overlap with the first transporting means (seen from a direction perpendicular to the transporting plane of the strings). It is also possible, that the transport path of the strings on the first transporting means may be wider than the width of the first transporting means itself, e.g. the width of a conveyor belt. The width of the transporting path being defined by extending longitudinal connectors. In such an embodiment the working area of the interconnecting station and the pressing zone of the pressing means need not overlap with the first transporting means. The interconnecting station is preferably stationary with respect to the transport movement of the first transporting means. I.e. the end portions of longitudinal connectors - with the cross connectors already positioned on the end portions of the longitudinal connectors - are moved through the working area of the interconnecting station. The working area is that area of the interconnecting station, in which an automatic connecting procedure takes place; with other words: where the connectors are subjected to the action (welding, soldering process) of the interconnecting station.

The interconnecting station may be e.g. adapted to perform one or more of the following processes: soldering, gluing, (cold) welding, electro-plating, crimping, bonding, (plasma) sputtering, printing and any other way of electrically

interconnecting.

A string according to the present invention may be formed from solar cells, i.e. at least two, preferably multiple solar cells. However, it would be also possible that a string is build up from only one solar cell that is string-shaped, i.e. having longitudinal extension, e.g. due to extending longitudinal connectors.

Preferably, the pressing means has at least one movable portion defining a transport path of (or pressing path for) the end portions of longitudinal connectors and/or the cross connector and adapted to press end portions of longitudinal connectors and the cross connector together, wherein preferably the movable portion is movable in a direction essentially parallel to the transporting direction of the first transporting means and/or preferably with a speed that is essentially the same as the first transporting speed. The movable portion allows to adapt the pressing procedure to the transport of the strings by the first transporting means. The pressing means (comprising e.g. a belt or a roll) may be adapted such that the movable portion moves and/or rotates with the same speed as the transporting speed of the first transporting means. The assembly of cross connector and longitudinal connectors are processed smoothly without the risk of a relative shift.

Preferably, a movable portion of the pressing means is formed by a first circulating belt running in at least one section parallel to a counter surface for pressing the at least one end portion of longitudinal connector and the cross connector between the belt and the counter surface against each other. This allows to reliably build up pressure onto the connector assembly. The counter surface may be stationary or movable. It would be also possible to use a portion of the first transporting means (which may be a conveyor belt) as counter surface.

Preferably, the counter surface is formed by a second circulating belt. This reliably reduces the risk of relative shifts of connectors. The second circulating belt is provided additionally to (i.e. independent from) the first transporting means. The extension of the second circulating belt is preferably larger than the first circulating belt, in order to receive the cross connectors in a reliable manner.

Preferably the first circulating belt and/or the second circulating belt are wider than the width of the cross connectors so that the cross connectors do not have to be positioned very accurately.

Preferably the first circulating belt and/or the second circulating belt is transparent to infrared radiation so that the temperature of the electrical interconnection can be monitored using a pyrometer. It may e.g. be made of a Teflon® material reinforced with glass fibres. Preferably, a movable portion of the pressing means comprises at least one pressing roll having a rotational axis that is essentially perpendicular to the transport direction of the first transporting means and essentially parallel to the transporting plane defined by the first transporting means. A pressing roll allows to locally build up pressure and may be used directly within the interconnecting station. Preferably, the pressing roll is arranged such as to mechanically act against the connectors within the perimeter defined by an induction coil for welding. The pressing roll may be provided additionally to pressing belt(s).

According to these embodiments movable pressing means may be provided for pressing the cross connectors to the ribbons. Movable pressing means may comprise or be a circulating belt or roll(s). Above the movable pressing means, particularly a conveyor belt, additional pressing means may be provided pushing down the pressing means to obtain higher pressure. Particularly, above or below the circulating belt at least one roll or at least one stationary element may serve as to press the belt towards the connectors.

In the case of pressing means in form of circulating belts tensioning means, e.g. a spring, may be provided for the tensioning the belts. Preferably, the interconnecting device comprises at least one second transporting means adapted to transport cross connector in a second transporting direction, and with a second transporting speed, wherein preferably the second transporting means is part of the pressing means.

Preferably, the second transporting means (e.g. a moving or circulating belt) has a receiving portion for receiving the cross connectors (upstream of the pressing zone) and a pressing portion extending within the pressing zone of the pressing means (i.e. where the pressing action is performed). The receiving portion of the second transporting means may extend in the feeding station.

In a preferred embodiment the second transporting means may be part of the pressing means and may be adapted for transporting or conducting the cross connector when already placed at (i.e. in contact with) the longitudinal connector or before (preferably: at a time shortly before) coming in contact with the longitudinal connector(s). The second transporting means has the function of conveying or conducting the cross connector during the step of pressing cross connector and end portion of longitudinal connector against each other. Preferably, the movable portion of the pressing means is formed by the second transporting means.

Preferably, the interconnecting device comprises at least one third transporting means adapted to transport cross connector in a third transporting direction and with a third transporting speed, wherein the third transporting means is part of the feeding station, wherein preferably the third transporting means comprises at least one g ripper adapted to pull cross connector in the third transporting direction.

Here, the third transporting means is part of the feeding station and is adapted for transporting cross connectors towards and/or in the vicinity of the end portions of the longitudinal connectors. The third transporting means is used for transporting cross connector prior to placing cross connector at the end portion(s) of longitudinal connector(s) and may also place them on the longitudinal connector(s).

In a preferred embodiment both, the feeding station and the pressing means, each comprises a transporting means. The second and third transporting means may be provided separately, i.e. they may be independent of each other.

In the embodiment having a second and/or third transporting means, also the feeding and/or pressing of the cross connectors can be automated. Preferably, the transport path(s) defined by the second and/or third transporting means also extend(s) laterally along the transport path of the strings on the first transporting means. Here, second and/or third transporting means, pressing means and interconnecting station define a processing path for the end portions of longitudinal connectors and cross connectors. That processing path extends laterally along the transport path of the strings on the first transporting means and preferably is a straight path. Preferably, the second transporting means is adapted to transport cross connector with the longitudinal extension of cross connector being essentially parallel to the second transporting direction and/or wherein the third transporting means is adapted to transport cross connector with the longitudinal extension of cross connector being essentially parallel to the third transporting direction. Transporting cross connector with its longitudinal extension being essentially parallel to the second transporting direction allows to bring and/or hold the cross connector in a defined position relative to the strings and/or to provide the cross connectors from an "endless" supply, wherein cutting means may be provided to give the cross connectors the desired length.

Preferably, the invention refers to an interconnecting device and interconnecting method for electrically interconnecting end portions of at least two - preferably multiple - longitudinal connectors of strings of solar cells by means of cross connector(s) - thus forming an electrically interconnected solar cell matrix.

The strings have longitudinal connectors extending essentially in longitudinal direction of a string and protruding from the ends of the string (i.e. from the solar cells forming the ends of the string). The longitudinal connectors may be a plurality of wires, a mesh or a foil. They may protrude from the end of the strings and be used for the cross-connection with cross connector(s). The term "end portion" of longitudinal connector is understood as that portion projecting beyond an end of the string; with other words: projecting beyond the solar cell forming an end of the string.

The second and/or third transporting means may comprise a conveyor belt. The second and/or third transporting means may also comprise an active holding means for holding the cross connectors. This may be e.g. a suction belt portion for holding the cross connectors. Alternative holding means may comprise an electrostatic charger or a belt (partially) made of a sticky material. The second and/or third transporting means may be also formed from a movable arrangement of suction g rippers.

With the invention it is possible to solder the cross connectors to the longitudinal connectors (or ribbons) while the strings are in their final relative position. The final relative position most commonly being an anti-parallel arrangement of the strings, i.e. the polarity of every second string is reversed. Other ways of interconnecting strings are conceivable as well. The cross connectors are moved along with the strings thereby passing an interconnecting station. The interconnecting station may comprise e.g. an inductive (or any other, preferably touch-less) welding machine for soldering the cross connectors to the longitudinal connectors (or ribbons).

The present invention may be realized by cost-effective machinery to solder the cross connectors to the longitudinal connectors e.g. while the string are transported to the lay-up station, thus saving time. The inventive device is highly flexible an can be easily adapted to solder cross connectors of different lengths, with different number of soldering joints (different number of ribbons or even a mesh of wires) and in different locations to the end portions of longitudinal connectors extending beyond the ends of the strings.

According to the invention it is possible to interconnect longitudinal connectors belonging to a single string (the "tabbed" string may be connected to other strings by other means or in a subsequent step or the cross connector is used for leading to the interconnection and junction box) or to interconnect longitudinal connectors of different strings.

The feeding station is adapted to bring the cross connector in the vicinity to the end portions of longitudinal connectors, such that the cross connector overlaps with at least one longitudinal connector protruding from a string. Preferably, the third transporting means moves essentially with the same speed as the first transporting means, such that a defined relative position between cross connector and longitudinal connectors can be achieved. Also the interconnecting device and the pressing means allow a continuous process. Thus, preferably the first transporting means moves the strings along the feeding station, the pressing means and the interconnecting station without stopping.

The interconnecting means creates an electrical connection but also a mechanical connection (soldering or welding) between cross connector and longitudinal connectors. The longitudinal connectors and/or the cross connectors may be coated with a soldering paste so that they can be soldered with each other right away.

Additionally, soldering flux may be applied to the longitudinal connectors and/or to the cross connectors prior to the interconnecting process in the interconnecting station. Preferably, the transporting direction of the second transporting means and/or the third transporting means is essentially parallel to the transporting direction of the first transporting means. A parallel transporting direction prior to releasing (e.g. laying down) cross connector to the end portions of longitudinal connectors allows a defined alignment of the cross connector with respect to the string(s), i.e. it is not necessary to change the orientation of the cross connector, once moving into the second or third transport direction. The term 'second and/or third transporting direction' may be understood in that at least one transport section defined by the second and/or third transporting means has a transporting direction that is essentially parallel to the first transporting direction.

Preferably, (at least during the feeding process) the second transporting speed and/or the third transporting speed is essentially the same as the transporting speed of the first transporting means. The feeding procedure and/or the pressing procedure is optimally adapted to the transport of the strings by the first transporting means. Releasing the cross connector from the third transporting means (e.g. laying down the cross connector on the end portions of longitudinal connectors) results in an exact relative position between cross connector and longitudinal connectors. Preferably, the interconnecting device comprises a cutting device for cutting cross connector into pieces, wherein preferably the transporting path defined by the third transporting means extends through the working area of the cutting device. This allows to use endless wire (e.g. wound on a reservoir or supply spool) for the cross connectors. The cutting device may be arranged in immediate vicinity of the transporting path of the first transporting means. The feeding is simplified and the cutting of cross connectors may be done in immediate vicinity of the first transporting means.

The cross connectors may be supplied from a spool, be cut to the appropriate length and optionally be stretched so that they are straighter than they are on the spool. This may be important so that cross connectors are not bent and extend

perpendicularly to the longitudinal direction of the strings (or: not bent out of the plane the strings run in, i.e. the transporting plane of the first transporting means). Straightening the cross connectors prior to placing them onto the longitudinal connectors prevents the cross connectors from being curved out from the plane of the strings. This measure guarantees that the end portions of the longitudinal connectors lie on a straight line or in a straight plane, respectively.

The pressing means is arranged downstream of the third transporting means.

Preferably, the extension of the pressing means in the first transporting direction is shorter than that of the first transporting means. Preferably, the interconnecting station comprises at least one - preferably contactless - heating means for heating up the end portions of the longitudinal connector and/or the cross connector, wherein preferably the heating means comprises at least one induction element, particularly a coil, winding(s) or loop(s). The connectors are heated during their travel through the interconnecting station. There is not necessity to stop the movement of the strings. Also glue may be activated by heat. Any heating means may be used, preferably touch-less heating means are used so that no friction occurs between pressing means and heating means and between cross connector and pressing means, thus preventing wear and soiling. The heating means may comprise an induction coil extending above or below the transport path of the cross connector (e.g. above or below the pressing means. In the case of two coils (above and below) essentially the same electrical power is applied to both coils.

Heating in the zones may be determined by the distance of the inductive coil(s) to the connectors, by the current through the coil(s) and/or by the number of loops of the coil (s). The coil may be arranged above and/or below the transport path of the connectors.

The coil(s) may be wound in a plane parallel to the transporting direction or perpendicular to the transporting direction thereby forming a C-iike shape forming an opening for the connectors to extend through.

Preferably, the induction element extends adjacent to and/or surrounds at least one movable portion of the pressing means. Pressing force can be applied in the immediate vicinity of the welding process (i.e. directly in the working area of the welding or soldering means).

Preferably, the induction element is arranged on that side of the movable part (wherein that movable part is preferably a belt) of the pressing means facing away from the transport path of the first transporting means.

Preferably, the heating means comprises at least two induction elements (e.g. coils) enclosing from opposite sides, preferably from the upper and lower side, a transport path section of the end portions of longitudinal connectors and the cross connectors as defined by the pressing means. This allows a uniform heating and thus a reliable soldering or welding process to connect cross connector(s) with longitudinal connectors. The interconnecting device may comprise as interconnecting station a soldering or welding device. In the case of a laser welding device the pressing means are preferably transparent to electromagnetic radiation. An alternative embodiment an ultra-sonic welding device can be provided. The interconnecting device may further comprise

- a gluing device for applying glue to (future) connection points on the longitudinal connectors (wherein cross connector is placed on these points and the glue is heated e.g. between belts); and/or

- crimping machine for deforming longitudinal connector and/or cross connector. Preferably, the interconnecting station comprises a pre-heating zone upstream of the heating means and/or a cooling zone downstream of the heating means. The pre-heating zone may comprises a separate heating means or the heating means used for welding works with reduced power when the connectors travel through the pre-heating zone. The cooling zone may comprise active cooling means, e.g. a ventilator for venting air.

As already mentioned, separate pre-heating means may be provided (alternatively to a single large heating unit) for material preheating. The cross connectors or longitudinal connectors (ribbons) or both may be pre-heated, preferable to a temperature where the solder does not melt, because it may change the relative position of cross connector and ribbons. A subsequent soldering or welding zone may be provided where the temperature of the cross connector or longitudinal connectors or both is elevated above the soldering/welding temperature. It is preferred to apply the highest pressure within the transport path.

The cooling zone may be a zone where pressure is still applied, but the temperature is reduced: by adding less heat, by adding no heat or by active cooling.

Preferably, the feeding station comprises a reservoir spool for carrying cross connector in endless form. This allows a continuous and time-saving process without stopping the strings during their movement along the feeding station.

Preferably, the third transporting means comprises at least one g ripper adapted to pull cross connector in the third transport direction. As g ripper any kind of device is understood capable of holding the cross connector. In the case the cross connector is provided from an endless wire the g ripper grips the end of the wire and moves the wire along the cutting device or through the working area of the cutting device. Once the desired length has traveled along or through the cutting device the cutting device is activated and cuts cross connector from the endless wire. Preferably, the g ripper transports cross connector prior to cutting and/or subsequent to cutting with a transporting speed which is essentially the same as the transporting speed of the first transporting means. Means may be provided for attaching a new endless roll to the used-up endless wire as is known from the state of the art. Preferably, the third transporting means comprises two g rippers for tensioning cross connector. This allows to remove a bend from the cross connector in the case the cross connector is provided from an endless wire wound on a reservoir spool.

Preferably, the interconnecting device has on both sides of the first transporting means a second and/or third transporting means, an interconnecting station and a pressing means. This allows to interconnect strings on opposite sides at the same time. The interconnecting device may be thus adapted for connecting also the other ends of the strings, so that the string can be interconnected on both sides, preferably in time parallel.

Preferably, the feeding station defines at least two feeding tracks of cross connector, the feeding tracks being spaced from each other in a direction perpendicular to the transport direction and parallel to the transporting plane of the first transporting means. This allows to provide at least two cross connectors at the same time, in order to create an advanced connection pattern.

In an alternative embodiment the interconnecting device has on one side of the first transporting means at least two feeding stations defining at least two feeding tracks of cross connector, the feeding tracks being spaced from each other in a direction perpendicular to the transport direction of the first transporting means. This allows to individually bring cross connectors for different purposes and of different length towards the strings. A single string interconnecting device may thus have multiple tracks, meaning that if cross connectors need to be attached on different distances from the last cells of the strings the device can handle this. Moreover, the cross connectors transporting means and the interconnecting station may be wide enough to respectively support and serve both tracks. Alternatively, two neighboring cross connectors transporting means and/or two interconnecting means may be provided, one for each track. Heating means of the interconnecting station may extend over multiple tracks or be movable from one track to another. Two or more interconnecting devices may be provided on opposite sides of the first transporting means, so that cross connectors may be attached to a string on both of its ends.

The object is also achieved with an interconnecting method for electrically interconnecting at least one end portion of at least one longitudinal connector of at least one solar cell string to a cross connector, wherein longitudinal connector preferably extends essentially in longitudinal direction of the string and an end portion of longitudinal connector extends beyond the end of the string, the method being performed in an interconnecting device, preferably according to one of the preceding embodiments, and comprising the steps of: (a) transporting at least one string, preferably multiple strings arranged one after another, by a first transporting means in a first transporting direction, with a first transporting speed and with the longitudinal extension of the at least one string being essentially perpendicular to the first transporting direction;

(b) feeding cross connector to the at least one end portion of longitudinal connector;

(c) placing cross connector at end portion of longitudinal connector such that cross connector at least partially overlaps with end portion of longitudinal connector;

(d) pressing cross connector and end portion of the longitudinal connector against each other by a pressing means; (e) electrically interconnecting end portion of longitudinal connector with cross connector; wherein step e) is performed during step d), and wherein preferably step b) and/or step c) and/or step (d) and/or step (e) is/are performed during step a). Preferably, the strings are continuously moved by the first transporting means during all steps a) to e), i.e. without stopping, and preferably with an essentially constant speed.

Preferably, step d) is done while transporting cross connector in a second transporting direction and with a second transporting speed.

Preferably, the second transporting direction is essentially parallel to the

transporting direction of the first transporting means.

Preferably, the second transporting speed is - at least temporarily - essentially the same as the transporting speed of the first transporting means. Preferably, cross connector is transported with the second and/or third transporting means with the longitudinal extension of cross connector being essentially parallel to the second transporting direction.

Preferably, the cross connectors are straightened prior to step c), i.e. prior to placing them at end portions of longitudinal connectors. This is preferably done by tensioning cross connector by means of at least one g ripper, preferably by means of two g rippers holding the cross connector on its opposed ends.

In an embodiment multiple interconnecting devices may be distributed in a complete production line. E.g. two strings may be interconnected according to the present invention thereby forming a pair of strings interconnected with each other on one end (cross connector and longitudinal connectors forming an U-type run). From such pairs of strings the complete solar cell matrix may be formed in a later stage and/or in a different station. The interconnection of such pairs of strings may be also performed using the inventive or any other method.

Additionally, cutting means may be provided upstream or downstream of the interconnecting station for cutting protruding portions of the longitudinal connectors to an appropriate length.

The pressing means and/or the second transporting means (for transporting the cross connectors) may be a conveyor belt made of any material that can withstand temperatures of more than 300°C, such as a glass fiber coated with PTFE or Teflon, If inductive heating is used, it is preferred that the belt is made from non-metalic material.

Exemplary 10-12 solar cells may be connected to a so-calied string. This is done in a so-called stringer. E.g. six of such strings are interconnected and form the cell matrix of the solar cell module. All cells of the matrix are preferably connected in series with each other.

It is possible that the solar cells of a string are interconnected with at least one, usually two longitudinal connectors (the number of longitudinal connectors equals the number of bus bars of a solar cell). The longitudinal connectors may be a wire, ribbons, a foil, mesh, etc.. Nowadays, almost all cells have three or more bus bars and thus ribbons. This is in order to achieve enough conductivity so that the ribbons can conduct the current without dissipating too much energy. The current can be as high as 8 Amps. Normally, the strings are interconnected using wider ribbons, enabling the use of only one single connection. The longitudinal connectors are normally connected to the bus bars by (normal) soldering, induction brazing, laser soldering, ultra-sonic soldering, hot air, infra-red, halogen or any other way. For an efficient solar module, the electrical resistivity of the connection between the ribbon and the bus bar must be minimized.

The thus formed cell matrix can be formed, e.g. laminated into a module in the usual ways.

Further embodiments of the invention are indicated in the figures and in the dependent claims. The list of reference marks forms part of the disclosure. The invention will now be explained in detail by the drawings. In the drawings:

Fig. 1 shows a string of solar cells connected with longitudinal connectors; Fig. 2 shows an array of strings with the longitudinal the support with the

longitudinal connectors being interconnected by means of cross connectors,

Fig. 3 to 8show an interconnecting device with the strings in different working

positions, Figs. 9 shows the interconnecting device in a side view, Fig. 10 shows the pressing means and the interconnecting station in detail, Fig. 1 1 show an embodiment of the interconnecting station,

Fig. 12 shows schematically a preferred embodiment of the interconnecting method.

Fig. 1 shows a string 3 of solar cells 2 being interconnected by means of longitudinal connectors 4 protruding at ends of string 3. In Fig. 1 longitudinal interconnectors 4 are formed from flat interconnectors, also called ribbons. Alternatively, longitudinal connectors maybe formed from a wire, a conductive foil or a mesh.

Fig. 2 shows a solar cell matrix formed from several (here: six) strings 3.

Longitudinal connectors 4 are interconnected by means of cross connectors 5. In the present embodiment the solar cells 2 are connected in series within the solar cell matrix.

Figs. 3 to 9 show a preferred embodiment of an interconnecting device 1 for electrically interconnecting end portions of longitudinal connectors 4 of at least one string 3 of solar cells 2 by means of cross connector 5. The end portions of longitudinal connectors 4 extend beyond the end of the string 3 (Fig. 1 ).

A first transporting means 10 in form of a conveyor belt is adapted to transport at least one string 3, preferably multiple strings 3 arranged one after another, in a first transporting direction 1 1 , with a first transporting speed and with the longitudinal extension of the at least one string 3 being essentially perpendicular to the first transporting direction 1 1. The strings 3 are transported along a defined transport path 24 having a width, which in the embodiment of Fig. 3 is slightly smaller than the width of the conveyor belt. The width of the transport path 24 of the strings 3 corresponds to the length of a string 3 measured between the outer edges of that solar cells forming the two ends of the solar cell string 3. As can be seen from Fig. 3 the working area of an interconnecting station 9 and the pressing zone of a pressing means 8 extend laterally along the transport path 24 of the strings 3 on the first transporting means 10 (i.e. along the transport path 24 of the strings 3 when transported with the first transporting means 10). The protruding end portions of longitudinal connectors 4 and the cross connectors 5 are conveyed through the working area of the interconnecting station 9 and the pressure zone of the pressing means 8 when the string 3 is transported by the first transporting means 10. The pressing means 8 comprises a second transporting means 20' adapted to transport cross connector 5 in a second transporting direction 21 ' and with a second transporting speed. Here, second transporting means 20' is formed by the circulating belt 18, to which the cross connectors 5 are laid. The circulating belt 18 constitutes a movable portion of the pressing means 8.

The second transporting means 20' has a portion for receiving the cross connectors 5 (upstream of the pressing zone) and a portion extending in the pressing zone of the pressing means 8.

The transporting direction 21 ' of the second transporting means 20' is essentially parallel to the transporting direction 1 1 of the first transporting means 10. The second transporting speed is essentially the same as the transporting speed of the first transporting means (10). The second transporting means 20' is adapted to transport cross connector (5) with the longitudinal extension of cross connector (5) being essentially parallel to the second transporting direction (21 ). At least one feeding station 6 is provided for feeding cross connector 5 to the end portions of longitudinal connectors 4. The feeding station 6 comprises a third transporting means 20 adapted to transport cross connector 5 in a third transporting direction 21. with a third transporting speed and with the longitudinal extension of cross connector 5 being essentially parallel to the third transporting direction 21 . The third transporting means 20 is part of the feeding station 6 and thus adapted for transporting cross connectors 5 towards and/or in the vicinity of the end portions of the longitudinal connectors 4. Here, the third transporting means 20 is used for transporting cross connector 5 prior to placing cross connector 5 at the end portion(s) of longitudinal connector(s) 4. In the present embodiment the feeding station 6 comprises a reservoir spool 16 for carrying one or multiple cross connectors 5 in (semi-)endless form (see also Fig. 9). A pulley deflects the moving direction of cross connector 5 in a direction parallel to the first transporting direction 1 1 . The third transporting means 20 comprises a g ripper 22 adapted to pull cross connector 5 in that second transport direction 21 (Fig. 3 to 5). The transport direction 21 of the third transporting means 20 is essentially parallel to the transporting direction 1 1 of the first transporting means 10. The transporting speed of the third transporting means 20 is preferably essentially the same as the transporting speed of the first transporting means 10, at least when the cross connectors 5 are connected to the end portions of longitudinal connectors

4.

The feeding station 6 comprises a cutting device 7 for cutting cross connector 5 into pieces, wherein the transporting path defined by the third transporting means 20 extends through the working area of the cutting device 7. A second g ripper 23 in cooperation with the first g ripper 22 allows to tension cross connector 5 after being cut, in order to provide straightened cross connectors 5. Second g ripper 23 is also used to hold the end of the cross connectors 5 still on the reservoir spool 16. The g ripper 22 holding the cross connector 5 moves in the second transporting direction. Subsequently, the gripper 22 releases cross connector 5 (Fig. 5) and thus places cross connector 5 on the end portions of longitudinal connectors 4 such that cross connector 5 at least partially overlaps with end portions of longitudinal connectors 4. Alternatively the cross connector 5 is placed on belt 19 and the end portions of longitudinal connectors 4 are moved over it.

Downstream of the feeding station 6 an interconnecting station 9, preferably a welding or soldering station, is provided for electrically interconnecting the end portions of longitudinal connectors 4 with cross connector 5.

At least one pressing means 8, e.g. comprising belt 18, is provided for pressing cross connector 5 and end portions of longitudinal connectors 4 against each other (Fig. 7), wherein at least a portion of the pressing means 8 extends in the working area of the interconnecting station 9.

In the embodiment shown in Fig. 3 the pressing means 8 has a second transporting means 20' defining a second transport direction 2Γ. The second transporting means 20' is adapted for transporting or conducting the cross connector 5 when already placed at (i.e. in contact with) the longitudinal connector 4. Here, the second transporting means 20' has the function of conveying or conducting the cross connector 5 during the step of pressing cross connector 5 and end portion of longitudinal connector 4 against each other. The second transporting means 20' of the pressing means 8 may be formed by one belt 18 and/or at least two belts 18, 19 for receiving connectors 4, 5 in between. The belts may also transmit the pressing force as will be described later. Preferably, the second transporting speed and the second transporting direction 21 ' of the second transporting means 20' (being part of the pressing means 8) are essentially the same as the transporting speed and the first transporting direction 1 1 of the first transporting means 10. In the preferred embodiment shown in the Figs, both, the feeding station 6 and the pressing means 8, each comprises a transporting means 20, 20'.

The transporting path of the second transporting means 20' and/or the third transporting means 20, the working area of the interconnecting station 8 and the pressing zone of the pressing means 7 extend laterally along the transport path of the strings when transported by the first transporting means 10, i.e. the transport path of the strings 3 being defined by the first transporting means 10.

The pressing means 8 has a movable portion defining a transport path of the end portions of longitudinal connectors 4 and the cross connector 5. Pressing means 8 is adapted to transmit pressure on the end portions of longitudinal connectors 4 and the cross connector 5 (i.e. pressing them together, e.g. with belts 18 and 19) when transported by the first transporting means 10. The movable portion is movable in a direction essentially parallel to the transporting direction 1 1 of the first transporting means 10. As can be seen from Fig. 1 to 10 the movable portion of the pressing means 8 is formed by a first circulating belt 18 running in at least one section parallel to a counter surface for pressing the end portions of longitudinal connectors 4 and the cross connector 5 between the belt 18 and the counter surface against each other. In the present embodiment the counter surface is formed by a second circulating belt 19. Alternatively the counter surface may e.g. also be a low friction surface. From Fig. 1 1 it can be seen that the pressing means 8 may further comprise a pressing roll 17 having a rotational axis that is essentially perpendicular to the transport direction 1 1 of the first transporting means 10. The pressing roll 17 presses against the belt 18 and belt 18 transmits the force of the pressing roll 17 to the connectors 4, 5. The interconnecting station 9 comprises at least one - preferably contactless (in this document meaning that it need not exert a force in order to connect the elements to be connected) - heating means 13 for heating up the end portions of the longitudinal connector 4 and/or the cross connector 5 (for soldering or welding). In the embodiment shown in Figs. 10 and 1 1 the heating means 13 comprises an induction coil 15. Alternate embodiments may comprise a laser head or ultra-sonic welding head. As can be seen from Fig. 1 1 the induction coil 16 surrounds the pressing roll 17.

The heating means 13 of Fig. 10 and 1 1 comprises two induction coils 15 (that may be electrically connected in parallel, in series or to different power sources) enclosing from opposite sides (from the upper and lower side) a transport path section of the end portions of longitudinal connectors 4 and the cross connectors 5 as defined by the pressing means 8. The circulating belts 18 and 19 also extend between the coils 15.

As can be seen from Fig. 10 the interconnecting station 9 comprises a pre-heating zone 12 (for pre-heating connectors 4, 5) upstream of the heating means 13 and a cooling zone 14 downstream of the heating means 13. Contrary to the embodiment shown, the interconnecting device 1 may have on both (lateral) sides of the first transporting means 10 a second or third transporting means 20, 20', an interconnecting station 9 and a pressing means 8. This allows to interconnect strings 3 on both ends while not removing them from first transporting means 10 or even in time parallel. It is also possible that the feeding station 6 defines at least two feeding tracks of cross connector 5, the feeding tracks being spaced from each other in a direction perpendicular to the transport direction 1 1 of the first transporting means 10.

Alternatively, the interconnecting device 1 has on one side of the first transporting means 10 at least two feeding stations 6 defining at least two feeding tracks of cross connector 5, the feeding tracks being spaced from each other in a direction perpendicular to the transport direction 1 1 of the first transporting means 10. This allows to place cross connectors 5 in parallel as shown in Fig. 2 (upper ends of strings 3).

The interconnecting method for electrically interconnecting end portions of longitudinal connectors 4 of at least one string 3 of solar cells 2 by means of cross connector 5 can be seen from the Figs. 3 to 8 and is schematically depicted in figure 12. Thereby end portions of longitudinal connectors 4 extend beyond the ends of the string 3 (Fig. 1 ).

The method comprises following steps:

Step (a): transporting at least one string 3, preferably multiple strings 3 arranged one after another, by a first transporting means 10 in a first transporting direction 1 1 , with a first transporting speed and with the longitudinal extension of the at least one string 3 being essentially perpendicular to the first transporting direction 1 1 (starting in the left portion of Fig. 3).

Step (b): feeding cross connector 5 to the end portions of longitudinal connectors 4 by a third transporting means 20 transporting cross connector 5 in a third

transporting direction 21 , with a third transporting speed which is preferably essentially the same as the first transporting speed of the first transporting means (10) and with the longitudinal extension of cross connector 5 being preferably essentially parallel to the second transporting direction 21 (Figs. 3 to 5). Step (c): placing cross connector 5 at end portions of longitudinal connectors 4 such that cross connector 5 at least partially overlaps with end portions of longitudinal connectors 4. In Fig. 5 the g ripper 22 releases cross connector 5. This is preferably done above second circulating belt 19. For this purpose the second circulating belt has a larger extension in the first transporting direction 1 1 than the first circulating belt. The g ripper 22 then re-moves towards its start position, in order to grip another cross connector 5.

Step (d): pressing cross connector 5 and end portions of longitudinal connectors 4 against each other by a pressing means 8 (Fig. 7)

Step (e): electrically interconnecting end portions of longitudinal connectors 4 with cross connector 5 (Fig. 7).

As can be seen from the preferred embodiment of Fig. 12 step e) is performed during step d), and the steps b) to e) are performed during step a). Preferably, the strings 3 are continuously moved by the first transporting means 10 during all steps a) to e), i.e. without stopping, and preferably with an essentially constant speed. The embodiments as described with respect to the figures are preferred embodiments. As already mentioned and apparent from the claims, particularly the second transporting means is an optional feature for the present invention. In an embodiment, in which a second transporting means is provided it would be also possible that belt 19 or belt 19 in cooperation with belt 18 constitute(s) a part of the second transporting means, since they have - additional to their pressing function - also transporting function.

The invention is not restricted to these embodiments. Other variants will be obvious for the person skilled in the art and are considered to lie within the scope of the invention as formulated in the following claims. Individual features described in above specification, particularly with respect to the figures may be combined with each other to form other embodiments and/or applied mutatis mutandis to what is described in the claims and to the rest of the description.

List of reference signs

1 Interconnecting device

2 solar cell

3 solar cell string

4 longitudinal connector

5 cross connector

6 feeding station

7 cutting device

8 pressing means

9 interconnecting station

10 first transporting means

1 1 first transporting direction

12 pre-heating zone

13 heating means

14 cooling zone

15 induction element

16 reservoir spool

17 pressing roll

18 belt

19 belt

20 third transporting means (part of the feeding station 6) 20' second transporting means (part of the pressing means

21 third transporting direction

21 ' second transporting direction

22 g ripper

23 g ripper

24 string transport path

Claims

Interconnecting device (1 ) for electrically interconnecting at least one end portion of at least one longitudinal connector (4) of at least one solar cell string (3) to a cross connector (5), the longitudinal connector (4) preferably extending essentially in longitudinal direction of the string (3), wherein the interconnecting device (1 ) comprises:

- first transporting means (10) adapted to transport the at least one string (3), preferably multiple strings (3) arranged one after another, in a first transporting direction (1 1 ) and with a first transporting speed, wherein preferably the first transporting means (10) is a conveyor belt;

~ at least one feeding station (6) for feeding cross connector (5) to the end portion of the at least one longitudinal connector (4);

- at least one interconnecting station (9), preferably a welding or soldering station, for electrically interconnecting the at least one end portion of longitudinal connector (4) with cross connector (5); at least one pressing means (8) for pressing cross connector (5) and end portion of longitudinal connector (4) against each other, wherein at least a portion of the pressing means (8) extends in the working area of the interconnecting station (9); wherein the working area of the interconnecting station (9) and the pressing zone of the pressing means (8) extend laterally along the transport path (24) of the strings (3) on the first transporting means (10) and/or in a lateral region of the first transporting means (10).

Interconnecting device according to claim 1 , wherein the pressing means (8) has at least one movable portion defining a transport path of the end portions of longitudinal connectors (4) and/or the cross connector (5) and adapted to press end portions of longitudinal connectors (4) and the cross connector (5) together, wherein preferably the movable portion is movable in a direction essentially parallel to the transporting direction (1 1 ) of the first transporting means (10) and/or preferably with a speed that is essentially the same as the first transporting speed.

3. Interconnecting device according to claim 2, wherein the movable portion of the pressing means (8) is formed by a first circulating belt (18) running in at least one section parallel to a counter surface for pressing the at least one end portion of longitudinal connector (4) and the cross connector (5) between the belt (18) and the counter surface against each other, wherein preferably the counter surface is formed by a second circulating belt (19) or by the first transporting means (10).

4. Interconnecting device according to claim 2 or 3, wherein a movable portion of the pressing means (8) comprises at least one pressing roll (17) having a rotational axis that is essentially perpendicular to the transport direction (1 1 ) of the first transporting means (10) and essentially parallel to the transporting plane defined by the first transporting means (10).

5. Interconnecting device according to one of the preceding claims, wherein the interconnecting device (1 ) comprises at least one second transporting means (20^') adapted to transport cross connector (5) in a second transporting direction (21 ') and with a second transporting speed, wherein preferably the second transporting means (20') is part of the pressing means (8).

6. Interconnecting device according to claim 5, wherein the movable portion of the pressing means (8) is formed by the second transporting means (20').

7. Interconnecting device according to one of the preceding claims, wherein the interconnecting device (1 ) comprises at least one third transporting means (20) adapted to transport cross connector (5) in a third transporting direction (21 ) and with a third transporting speed, wherein the third transporting means (20) is part of the feeding station (6), wherein preferably the third transporting means (20) comprises at least one g ripper (23) adapted to pull cross connector (5) in the third transporting direction (21 ).

Interconnecting device according to one of the claims 5 to 7, wherein the transporting direction (21 , 21 ') of the second transporting means (20') and/or of the third transporting means (20) is essentially parallel to the transporting direction (1 1 ) of the first transporting means (10).

9. Interconnecting device according to one of the claims 5 to 8, wherein the

second transporting speed and/or the third transporting speed is/are essentially the same as the transporting speed of the first transporting means (10).

10. Interconnecting device according to one of the claims 5 to 9, wherein the

second transporting means (20') is adapted to transport cross connector (5) with the longitudinal extension of cross connector (5) being essentially parallel to the second transporting direction (21 ') and/or wherein the third transporting means (20) is adapted to transport cross connector (5) with the longitudinal extension of cross connector (5) being essentially parallel to the third transporting direction (21 ).

Interconnecting device according to one of the preceding claims, wherein the interconnecting station (9) comprises at least one - preferably contactless - heating means (13) for heating up the end portions of the longitudinal connector (4) and/or the cross connector (5), wherein preferably the heating means (13) comprises at least one induction element (15), particularly a coil, windings(s) or loop(s).

Interconnecting device according to claim 1 1 , wherein the induction element (15) extends adjacent to and/or surrounds at least one movable portion of the pressing means (8) and/or wherein the induction element (15) is arranged on that side of the movable part of the pressing means facing away from the transport path of the first transporting means (10).

Interconnecting device according to claim 1 1 or 12, wherein the heating means (13) comprises at least two induction elements (15) enclosing from opposite sides, preferably from the upper and lower side, a transport path section of the end portions of longitudinal connectors (4) and the cross connectors (5) as defined by the pressing means (8).

14. Interconnecting method for electrically interconnecting at least one end portion of at least one longitudinal connector (4) of at least one solar cell string (3) to a cross connector (5), wherein longitudinal connector (4) preferably extends essentially in longitudinal direction of the string (3) and end portions of longitudinal connector (5) extend beyond the ends of the string (3), the method being performed in an interconnecting device (1 ), preferably according to one of the preceding claims, and comprising the steps of:

(a) transporting at least one string (3), preferably multiple strings (3) arranged one after another, by a first transporting means (10) in a first transporting direction (1 1 ), with a first transporting speed and with the longitudinal extension of the at least one string (3) being essentially perpendicular to the first transporting direction (1 1 );

(b) feeding cross connector (5) to the at least one end portion of longitudinal connector (4);

(c) placing cross connector (5) at end portion of longitudinal connector (4) such that cross connector (5) at least partially overlaps with end portion of longitudinal connector (4);

(d) pressing cross connector (5) and end portion of longitudinal connector (4) against each other by a pressing means (8);

(e) electrically interconnecting end portion of longitudinal connector (4) with cross connector (5); wherein step e) is performed during step d), and wherein preferably step b) and/or step c) and/or step d) and/or step e) is/are performed during step a).

15. Interconnecting method according to claim 14, wherein step d) is done while transporting cross connector (5) in a second transporting direction (21 ') and with

OC U! !U CSS ! j US UE i ο υΰυ, wherein the second transporting speed is at least temporarily essentially the same as the transporting speed of the first transporting means (10) and/or wherein cross connector (5) is transported with the longitudinal extension of cross connector (5) being essentially parallel to the second transporting direction (21 ').