Equipment for electrical contacting of wafer solar cells, inline production device and manufacturing process for a wafer solar cell

Abstract

The invention relates to a system for electrically contacting wafer solar cells, an inline production device, and a manufacturing process for a wafer solar cell. In particular, the invention relates to a system configured for electrically contacting wafer solar cells with a front-side electrode and a back-side electrode, an inline production device comprising such a system, and a manufacturing process for producing a wafer solar cell using the system or the inline production device. The object of the invention is therefore to provide a system for electrically contacting wafer solar cells which, when used in LECO processing, avoids contact interruptions with the front-side or back-side electrode. Furthermore, the system should also enable bifacial LECO processing of wafer solar cells. This object is achieved by the fact that the upper contact device(1) and the lower contact device (2) each has a first contact element and a second contact element, and these contact elements are designed as electrically conductive conveyor belts, the conveyor belts are guided circumferentially on at least two deflection rollers, and the rotational speed of the conveyor belts corresponds to the transport speed of the wafer solar cell (W) along the inline transport direction (i), and each section of the two circumferential conveyor belts of the upper contact device (1) rests against a section of the front electrode of the wafer solar cell (W), and each section of the two circumferential conveyor belts of the lower contact device (2) rests against a section of the rear electrode of the wafer solar cell (W), and the two circumferential conveyor belts of the upper contact device (1) and the two circumferential conveyor belts of the lower contact device (2) are perpendicular to the inline transport direction (i).They are each arranged at a distance from each other.

Description

[0001] The invention relates to a system for electrically contacting wafer solar cells, an inline production device, and a manufacturing method for a wafer solar cell. In particular, the invention relates to a system designed for electrically contacting wafer solar cells with a front-side electrode and a back-side electrode, an inline production device comprising such a system, and a manufacturing method that produces a wafer solar cell using the system or the inline production device.

[0002] Such a system is known from DE 10 2016 009 560 A1. It comprises an upper contact device for electrically contacting the front electrode of the wafer solar cell, a lower contact device for electrically contacting the back electrode of the wafer solar cell, and an electrical voltage source for applying a defined voltage to the wafer solar cell and regulating the current flow between the upper contact device and the lower contact device. This system is applied to a stationary contacted wafer solar cell, with a single roller or brush being guided along the stationary wafer solar cell to apply voltage to the wafer solar cell. Furthermore, a point light source is guided over the front of the wafer solar cell when the voltage is applied, thereby generating a light-induced current flow.This process is called LECO (Laser Enhanced Cell Optimization) because it particularly improves the electrical contact between the front electrode and the underlying semiconductor material of the wafer solar cell.

[0003] Furthermore, DE 10 2021 123 280 A1 discloses a system for electrically contacting wafer solar cells with a front-side electrode and a back-side electrode. This system comprises an upper contact device for electrically contacting the front-side electrode of the wafer solar cell, a lower contact device for electrically contacting the back-side electrode of the wafer solar cell, and an electrical voltage source for applying a defined voltage to the wafer solar cell and regulating the current flow between the upper contact device and the lower contact device. The upper contact device and the lower contact device are designed and configured to additionally mechanically convey the wafer solar cell during contacting along an inline transport direction for an inline production line for wafer solar cells.In one embodiment, the upper contact device has at least one upper contact element and the lower contact device has at least one lower contact element, wherein the upper and lower contact elements are each designed as a roller or roll with a contact circumference. In a further embodiment, in contrast to the previous embodiment, the lower contact device is designed as a conveyor belt that lies fully against the rear-side electrode and moves at the same speed as the wafer solar cell along the inline transport direction. The system for electrically contacting wafer solar cells known from DE 10 2021 123 280 A1 has generally proven itself. However, wafer solar cells with a typical thickness of approximately 150 µm to 180 µm can have thickness variations of up to 20 µm. The front-side electrode and the rear-side electrode can also have additional height variations of up to 10 µm due to manufacturing reasons.When using the known system for LECO processing, this can lead to contact failures between the contact elements, designed as rollers / rollers, and the front or rear electrode. This impairs homogeneous current flow and can cause damage from local discharges (lightning, hotspots). Furthermore, when using the system with a conveyor belt that fully adheres to the rear electrode, double-sided LECO processing of bifacial wafer solar cells is not possible, as the conveyor belt covers the rear side of the wafer solar cell, making it inaccessible for illumination.

[0004] WO 2007 / 118875 A2 discloses an electrolytic deposition process for solar cells in which the front-side electrode and the back-side electrode are each contacted with spaced-apart, conductive conveyor belts. The corrugations of the conveyor belts are subjected to the same potential.

[0005] From WO 2009 / 073501 A2 a method for contact improvement is known in which a voltage in forward or reverse direction is applied between the front side electrode and the back side electrode of solar cells and the front side is illuminated.

[0006] The object of the invention is therefore to create a system for electrically contacting wafer solar cells that, when used in LECO processing, prevents contact breaks with the front-side electrode or back-side electrode. Furthermore, the system should also enable double-sided LECO processing of bifacial wafer solar cells.

[0007] According to the invention, this object is achieved by a system having the features of patent claim 1. Furthermore, the object is achieved by an inline production device having the features of patent claim 10 and a manufacturing method having the features of patent claim 11. Advantageous modifications and further developments are specified in the subclaims.

[0008] The system for electrically contacting wafer solar cells with a front-side electrode and a back-side electrode comprises: - an upper contact device for electrically contacting the front electrode of the wafer solar cell, - a lower contact device for electrically contacting the backside electrode of the wafer solar cell and - an electrical voltage source to apply a defined voltage to the wafer solar cell and to regulate the current flow between the upper contact device and the lower contact device, - wherein the upper contact device and the lower contact device are designed and configured to additionally mechanically convey the wafer solar cell during contacting along an inline transport direction for an inline production line for wafer solar cells.

[0009] According to the invention, it is now provided: - that the upper contact device has a first upper contact element and a second upper contact element and the first upper contact element and the second upper contact element are designed as electrically conductive conveyor belts, and - that the two conveyor belts of the upper contact device are each guided around at least two deflection rollers and a rotational speed of the two conveyor belts corresponds to the transport speed of the wafer solar cell along the inline transport direction, and - that one section of each of the two circulating conveyor belts of the upper contact device rests against a section of the front-side electrode of the wafer solar cell, and - that the two circulating conveyor belts of the upper contact device are arranged at a distance from each other when viewed perpendicular to the inline transport direction, and - that the lower contact device has a first lower contact element and a second lower contact element and the first lower contact element and the second lower contact element are designed as electrically conductive conveyor belts, and - that the two conveyor belts of the lower contact device are each guided around at least two deflection rollers and a rotational speed of the two conveyor belts corresponds to the transport speed of the wafer solar cell along the inline transport direction, and - that one section of each of the two circulating conveyor belts of the lower contact device rests against a section of the backside electrode of the wafer solar cell, and - that the two circulating conveyor belts of the lower contact device are arranged at a distance from each other when viewed perpendicular to the inline transport direction.

[0010] The invention is based on the basic idea of ​​conveying wafer solar cells with a front electrode and a rear electrode by means of at least four circulating conveyor belts, with two of the at least four conveyor belts being positioned at the front electrode and two of the at least four conveyor belts being positioned at the rear electrode of the wafer solar cell. When the conveyor belts are positioned, the conveyor belts at the front and the conveyor belts at the rear are energized by the electrical voltage source with opposite polarity. The upper contact device and the lower contact device are thus designed to jointly convey wafer solar cells in a continuous process, which have metal contacts in the form of the electrodes on the front and rear.Contact between the upper contact device and the lower contact device and the wafer solar cell therefore occurs while the wafer solar cell is moved, so that it is electrically contacted by the contact devices from its front and rear sides. The electrical voltage source serves to bring the wafer solar cell into a predetermined semiconductor state. The voltage source is preferably designed to apply voltage to the upper contact device and the lower contact device and, via this, to apply a defined voltage to the wafer solar cell contacting it. In this way, in particular, the current flow between the upper contact device and the lower contact device and thus the current flow through the wafer solar cell can be regulated.

[0011] The system can therefore be used to optimize wafer solar cell contacts in the form of front and back electrodes and / or for characterizing wafer solar cells. The system is preferably used to optimize wafer solar cell contacts.

[0012] Wafer solar cells can be designed as monofacial or bifacial, as is well known. In a monofacial design, the front side of the wafer solar cell is the side of the wafer solar cell that receives light, typically sunlight, during normal use, while the back side is the side facing away from light during operation. In a bifacial design, the back side of the wafer solar cell is also designed to absorb light, typically sunlight, and convert it into electrical voltage. The back side of bifacial wafer solar cells is typically optimized to absorb diffuse scattered light. However, designs designed for direct irradiation with sunlight on both sides during normal use are also possible.

[0013] The polarity of the electrical voltage source is preferably adjustable in a range from 0 V to 50 V, more preferably in a range from 10 V to 25 V.

[0014] The contact pressure of the conductive conveyor belts on the front-side electrode and the back-side electrode of the wafer solar cell is preferably selected such that good electrical contact is made with the wafer solar cell, but no mechanical damage to the sensitive semiconductor wafer material occurs.

[0015] The system is advantageous for the electrical contacting of the front electrode of the wafer solar cell because the contact area is significantly increased by the use of electrically conductive conveyor belts compared to contacting with rollers or cylinders, thus preventing contact failures at the front electrode during LECO processing. The spacing of the two circulating conveyor belts of the upper contact device ensures that the coupling of the point light source onto the solar-active areas of the front of the wafer solar cell, which is necessary for LECO processing, is possible. The light emitted by the point light source can be directed onto the solar-active areas of the front of the wafer solar cell in the free area between the two conveyor belts. The system is therefore suitable for the LECO processing of monofacial and bifacial wafer solar cells with illumination of the front of the wafer solar cells.

[0016] The system is advantageous for electrically contacting the backside electrode of the wafer solar cell because the contact area is significantly increased by the use of electrically conductive conveyor belts compared to contacting with rollers or cylinders, thus preventing contact failures at the backside electrode during LECO processing. Likewise, the spacing of the two circulating conveyor belts of the lower contact device ensures that the point light source can also be coupled onto the backside of the wafer solar cell. This enables simultaneous, bilateral LECO processing of bifacial wafer solar cells. The light emitted by the point light source (or another point light source) can be directed onto the solar-active areas on the backside of the wafer solar cell in the free space between the two conveyor belts of the lower contact device.In principle, the system is also suitable for one-sided LECO processing of monofacial or bifacial wafer solar cells.

[0017] In advantageous embodiments of the system according to the invention, the spacing between the circulating conveyor belts is in a range of 1 / 50 to 1 / 4, preferably 1 / 50 to 1 / 10, more preferably 1 / 50 to 1 / 20, of the dimension of the wafer solar cell along the inline transport direction. The smaller the spacing between the conveyor belts, the larger the area contacted by the conveyor belts on the front or back of the wafer solar cell. However, as the spacing decreases, the requirements for guiding the point light source in the area between the adjacent conveyor belts increase.

[0018] In a first embodiment, the conveyor belts themselves are made of a conductive foil or an electrically conductive rubber.

[0019] In a further embodiment, the conveyor belts have a conductive coating.

[0020] It is proposed that the conductive coating be formed from a conductive foil, a conductive rubber, a conductive foam or a contact fleece.

[0021] Furthermore, it is proposed that the conveyor belts of the upper contact device and / or the conveyor belts of the lower contact device are electrically connected to the voltage source via at least one of the two respective deflection rollers.

[0022] In an advantageous embodiment, the at least two deflection rollers are spring-mounted. This improves the secure contact of the conveyor belts with the front electrode of the wafer solar cell or the back electrode of the wafer solar cell.

[0023] One embodiment provides that at least one of the deflection rollers is motor-driven.

[0024] In one embodiment, it is provided that the system has a laser device which moves or projects a laser beam transversely to the inline transport direction in a region formed by the spacing of the transport belts of the upper contact device over a front side of the wafer solar cell and / or in a region formed by the spacing of the transport belts of the lower contact device over a rear side of the wafer solar cell.

[0025] The laser device is preferably designed as a scanning laser capable of generating a high photocurrent. The movement or projection of the laser device is preferably carried out such that the photocurrent generated by the laser device flows via the front electrode and the at least one upper contact element, as well as the rear electrode and the at least one lower contact element, thereby improving the contact properties of the front electrode and / or the rear electrode. The laser device is moved perpendicular to the inline transport direction. Preferably, a laser scanning rate can be automatically adapted to a transport speed at which the wafer solar cell is conveyed in the inline transport direction.

[0026] Furthermore, to achieve the object, an inline production device for a wafer solar cell is proposed, which is equipped with the system according to the invention. In addition to the system described above, the inline production device has a plurality of additional stations for producing the wafer solar cell starting from a semiconductor wafer or from a wafer solar cell semi-finished product.

[0027] Furthermore, a manufacturing method for a wafer solar cell using the system according to the invention is proposed, in which an inline transport speed of the wafer solar cells along the inline transport direction of 0.1 to 60 m / min, preferably of 3 to 20 m / min and particularly preferably of 6 to 20 m / min is realized.

[0028] An embodiment of the invention is explained below with reference to the drawings. They show: Fig. 1 shows a schematic and not-to-scale spatial representation of a system according to a first embodiment during operation. The system is designed for electrically contacting wafer solar cells W with a front-side electrode (not shown) and with a back-side electrode (not shown). The system has an upper contact device 1 for electrically contacting the front-side electrode of the wafer solar cell W and a lower contact device 2 for electrically contacting the back-side electrode of the wafer solar cell W. Furthermore, the system has an electrical voltage source (not shown) for applying a defined voltage to the wafer solar cell W and for regulating the current flow between the upper contact device 1 and the lower contact device 2.The upper contact device 1 and the lower contact device 2 are designed and configured to additionally mechanically convey the wafer solar cell W during contacting along an inline transport direction i for an inline production line for wafer solar cells.

[0029] The upper contact device 1 has a first upper contact element 1.1 and a second upper contact element 1.2, wherein the first upper contact element 1.1 and the second upper contact element 1.2 are designed as electrically conductive conveyor belts. The two conveyor belts 1.1, 1.2 of the upper contact device 1 are each guided in a rotating manner on at least two deflection rollers 1.1a, 1.1b, 1.2a, 1.2b. A rotating speed of the two conveyor belts 1.1, 1.2 corresponds to the transport speed of the wafer solar cell W along the inline transport direction i. In each case, a section of the two rotating conveyor belts 1.1, 1.2 of the upper contact device 1 rests against a section of the front-side electrode of the wafer solar cell W. In the illustration, the lower sections of the two conveyor belts 1.1, 1.2 rest against the front-side electrode of the wafer solar cell W. The two circulating conveyor belts 1.1, 1.2 of the upper contact device 1 are arranged at a distance d1 from each other, viewed perpendicular to the inline transport direction.

[0030] The distances d1, d2 of the circulating conveyor belts are preferably in a range from 1 / 50 to 1 / 4, more preferably from 1 / 50 to 1 / 10, more preferably from 1 / 50 to 1 / 20, of the extent of the wafer solar cell W along the inline transport direction i. The distances d1, d2 do not necessarily have to be equal.

[0031] The lower contact device 2 has a first lower contact element 2.1 and a second lower contact element 2.1, wherein the first lower contact element 2.1 and the second lower contact element 2.2 are designed as electrically conductive conveyor belts. The two conveyor belts 2.1, 2.2 of the lower contact device 2 are each guided in a rotating manner on at least two deflection rollers 2.1a, 2.1b, 2.2a, 2.2b, wherein a rotating speed of the two conveyor belts 2.1, 2.2 corresponds to the transport speed of the wafer solar cell W along the inline transport direction i. One section of each of the two rotating conveyor belts 2.1, 2.2 of the lower contact device 2 rests against a section of the rear-side electrode of the wafer solar cell W. In the illustration, the upper sections of the two conveyor belts 2.1, 2.2 rest against the front-side electrode of the wafer solar cell W. The two circulating conveyor belts 2.1, 2.2 of the lower contact device 2 are arranged at a distance d2 from each other, viewed perpendicular to the inline transport direction i.

[0032] The conveyor belts 1.1, 1.2, 2.1, 2.2 moving at the transport speed of the wafer solar cell W in the inline transport direction i convey the wafer solar cell W and contact the front electrode and the back electrode so that the defined voltage generated by the electrical voltage source is applied to the front electrode and the back electrode of the wafer solar cell W. The arrows shown on the deflection rollers 1.1a, 1.1b, 1.2a, 1.2b, 2.1a, 2.1b, 2.2a, 2.2b symbolize the direction of rotation of these deflection rollers 1.1a, 1.1b, 1.2a, 1.2b, 2.1a, 2.1b, 2.2a, 2.2b, which is transferred to the respective conveyor belts 1.1, 1.2, 2.1, 2.2 and thus results in the inline transport direction i of the wafer solar cell W symbolized by the arrows when conveying the wafer solar cell W.

[0033] In the illustrated embodiment, the conveyor belts 1.1, 1.2, 2.1, 2.2 are made of an electrically conductive rubber. However, the invention is not limited to this. For example, the conveyor belts 1.1, 1.2, 2.1, 2.2 can also be made of a conductive foil. Likewise, the conveyor belts 1.1, 1.2, 2.1, 2.2 can also have a conductive coating, which is formed, for example, from a conductive foil, a conductive rubber, a conductive foam, or a contact fleece.

[0034] The conveyor belt 1.1 of the upper contact device 1 is electrically connected to the voltage source via at least one of the two deflection rollers 1.1a, 1.1b. Similarly, the conveyor belt 1.2 of the upper contact device 1 is electrically connected to the voltage source via at least one of the two deflection rollers 1.2a, 1.2b, the conveyor belt 2.1 of the lower contact device 2 is electrically connected to the voltage source via at least one of the two deflection rollers 2.1a, 2.1b, and the conveyor belt 2.2 of the lower contact device 2 is electrically connected to the voltage source via at least one of the two deflection rollers 2.2a, 2.2b. The two conveyor belts 1.1, 1.2 are connected to one pole of the voltage source, and the two conveyor belts 2.1, 2.2 are connected to the other pole of the voltage source. However, the invention is not limited to an electrical connection of the conveyor belts 1.1, 1.2, 2.1, 2.2 via the deflection rollers 1.1a, 1.1b, 1.2a, 1.2b, 2.1a, 2.1b, 2.2a, 2.2b.For example, additional rollers can be provided for the electrical connection of the conveyor belts to the voltage source.

[0035] For the movement of the conveyor belts 1.1, 1.2, 2.1, 2.2, at least one of the two associated deflection rollers 1.1a, 1.1b, 1.2a, 1.2b, 2.1a, 2.1b, 2.2a, 2.2b is motor-driven.

[0036] However, the invention is not limited to this. Drive can also be provided by additional rollers.

[0037] Furthermore, the system comprises a laser device 4, which moves or projects a laser beam transversely to the inline transport direction i in an area formed by the spacing of the conveyor belts 1.1, 1.2 of the upper contact device 1 over a front side of the wafer solar cell W and in an area formed by the spacing of the conveyor belts 2.1, 2.2 of the lower contact device 2 over a rear side of the wafer solar cell W. With this embodiment, LECO processing of a bifacial wafer solar cell W is possible with simultaneous illumination of the front and rear sides. However, the invention is not limited to this. The laser device 4 can also be designed such that the laser beam is moved or projected only over the front side or only over the rear side of the wafer solar cell.If the laser beam is directed only over the front side of the wafer solar cell, LECO processing of monofacial and bifacial wafer solar cells is possible while illuminating their front side. If the laser beam is directed only over the back side of the wafer solar cell, LECO processing of bifacial wafer solar cells is possible while illuminating their back side.

[0038] Fig. 2 shows a section of the design of the system according to Fig. 1 with the conveyor belts 2.1, 2.2, whereby the area between the conveyor belts 2.1, 2.2 with the wafer solar cell W partially located therebetween is also shown as a detailed illustration. The conveyor belts 1.1, 2.1 and the conveyor belts 1.2, 2.2 are spaced apart from each other so that they do not touch each other. For improved contact of the conveyor belts 1.1, 1.2, 2.1, 2.2 against the front electrode and the rear electrode, the deflection rollers 1.1a, 1.1b, 1.2a, 1.2b, 2.1a, 2.1b, 2.2a, 2.2b are spring-mounted. In the absence of a wafer solar cell, the conveyor belts 1.1, 2.1 and the conveyor belts 1.2, 2.2 are spaced apart at a distance h1 that is smaller than the thickness h2 of the wafer solar cell. When a wafer solar cell is conveyed between the conveyor belts 1.1, 2.1 or the conveyor belts 1.2, 2.2, the deflection rollers 1.1a, 2.1a, 1.2a, 1.2b, 2.1a, 2.1b, 2.2a, 2.2b are guided by the spring-loaded mounting of the deflection rollers 1.1a, 1.1b, 1.2a, 1.2b, 2.1a, 2.1b, 2.2a, 2.2b.1b, 2.1b, the deflection rollers 1.2a, 2.2a and the deflection rollers 1.2b, 2.2b are moved relative to each other, so that their distance from each other is increased and thus also the distance between the conveyor belts 1.1, 2.1 and the conveyor belts 1.2, 2.2 from each other is increased. The distance between the conveyor belts 1.1, 2.1 and the conveyor belts 1.2, 2.2 from each other, with the wafer solar cell W in between, corresponds to the thickness h2 of the wafer solar cell W. Via the spring-loaded mounting of the deflection rollers 1.1a, 1.1b, 1.2a, 1.2b, 2.1a, 2.1b, 2.2a, 2.2b, the conveyor belts 1.1, 1.2, 2.1, 2.2 are pressed against the front electrode or the back electrode of the wafer solar cell W for secure contact. The spring bearing of the deflection rollers 1.1a, 1.1b, 1.2a, 1.2b thus acts in the direction of the front side electrode of the wafer solar cell W located in between and the spring bearing of the deflection rollers 2.1a, 2.1b, 2.2a, 2.2b acts in the direction of the front side electrode of the wafer solar cell W located in between.The spring-loaded mounting of the deflection rollers advantageously provides for automatic adjustment of the distance h1 to the thickness h2 of the wafer solar cell W, which is subject to variations.

[0039] Fig. Figure 3 shows a further embodiment of the system according to the invention for electrically contacting wafer solar cells W with a front-side electrode and a back-side electrode. In this system, three conveyor belts 1.1, 1.2, 1.3 are arranged one behind the other for contacting the front-side electrode, and three conveyor belts 2.1, 2.2, 2.3 are arranged one behind the other for contacting the back-side electrode. Each conveyor belt is guided in a rotating manner by two deflection rollers. Furthermore, in addition to the deflection rollers 1.1a, 1.1b, 1.2a, 1.2b, 2.1a, 2.1b, 2.2a, 2.2b, 3.1a, 3.1b, 3.2a, 3.2b, each conveyor belt is assigned two further rollers 1.1c, 1.2c, 2.1c, 2.2c, 3.1c, 3.2c, which are used, for example, to drive the respective conveyor belt and / or to electrically connect the respective conveyor belt to the corresponding pole of the voltage source. For reasons of clarity, Fig. 3 shows only the reference numerals of the deflection rollers 2.1a, 2.1b and the additional rollers 2.1c of the conveyor belt 2.1. The reference numerals of the other conveyor belts 1.1, 1.2, 1.3, 2.2, 2.3 are analogous. Here, too, the invention is not limited to the number of additional rollers shown. In the free area formed between the conveyor belt 1.1 and the conveyor belt 1.2, a first laser 4.1 of the laser device 4 is moved or projected onto the front side of a wafer solar cell W conveyed between the conveyor belts 1.1, 1.2, 2.1, 2.2. In the free area formed between the conveyor belt 2.2 and the conveyor belt 2.3, a second laser 4.2 of the laser device 4 is moved or projected onto the back side of a bifacial wafer solar cell W conveyed between the conveyor belts 1.2, 1.3, 2.2, 2.3.With the system design shown, a first LECO processing of a bifacial wafer solar cell W is possible with the front side of the wafer solar cell W illuminated, followed by a second LECO processing of this bifacial wafer solar cell W with the back side of the wafer solar cell illuminated. Of course, the arrangement of the first laser 4.1 and the second laser 4.2 can also be reversed, so that a first LECO processing of a bifacial wafer solar cell W is carried out with the back side of the wafer solar cell W illuminated, followed by a second LECO processing of this bifacial wafer solar cell W with the front side of the wafer solar cell illuminated. Fig. 3 there are several wafer solar cells W1, W2, W3 arranged one behind the other in the system.

[0040] One of the systems described above is integrated into an inline production device for a wafer solar cell W (not shown).

[0041] When carrying out a manufacturing method for a wafer solar cell W using one of the above-described systems or the above-mentioned inline production device, an inline transport speed of the wafer solar cells W along the inline transport direction i of 0.1 to 60 m / min, preferably of 3 to 20 m / min and particularly preferably of 6 to 20 m / min is realized. List of reference symbols 1 upper contact device 1.1 first upper contact element, conveyor belt 1.1a Deflection pulley 1.1b Deflection pulley 1.1c role 1.2 second upper contact element, conveyor belt 1.2a Deflection pulley 1.2b Deflection pulley 1.2c roll 1.3 Conveyor belt 1.3a Deflection pulley 1.3b Deflection pulley 1.3c role 2 lower contact device 2.1 first lower contact element, conveyor belt 2.1a Deflection pulley 2.1b Deflection pulley 2.1c role 2.2 second lower contact element, conveyor belt 2.2a Deflection pulley 2.2b Deflection pulley 2.2c role 2.3 Conveyor belt 2.3a Deflection pulley 2.3b Deflection pulley 2.3c role 4 Laser device 4.1 first laser 4.2 second laser

Claims

[1] System for electrically contacting wafer solar cells (W) with a front-side electrode and with a back-side electrode, comprising: - an upper contact device (1) for electrically contacting the front electrode of the wafer solar cell (W), - a lower contact device (2) for electrically contacting the back electrode of the wafer solar cell (W) and - an electrical voltage source for applying a defined voltage to the wafer solar cell (W) and for regulating the current flow between the upper contact device (1) and the lower contact device (2), - wherein the upper contact device (1) and the lower contact device (2) are designed and configured to additionally mechanically convey the wafer solar cell (W) during contacting along an inline transport direction (i) for an inline production line for wafer solar cells, characterized by , - that the upper contact device (1) has a first upper contact element and a second upper contact element and the first upper contact element and the second upper contact element are designed as electrically conductive conveyor belts, and - that the two conveyor belts of the upper contact device (1) are each guided in a rotating manner on at least two deflection rollers and a rotational speed of the two conveyor belts corresponds to the transport speed of the wafer solar cell (W) along the inline transport direction (i), and - that a section of each of the two circulating conveyor belts of the upper contact device (1) rests against a section of the front side electrode of the wafer solar cell (W), and - that the two circulating conveyor belts of the upper contact device (1) are arranged at a distance from each other when viewed perpendicular to the inline transport direction (i), and - that the lower contact device (2) has a first lower contact element and a second lower contact element, and the first lower contact element and the second lower contact element are designed as electrically conductive conveyor belts, and - that the two conveyor belts of the lower contact device (2) are each guided in a rotating manner on at least two deflection rollers and a rotational speed of the two conveyor belts corresponds to the transport speed of the wafer solar cell (W) along the inline transport direction (i), and - that a section of each of the two circulating conveyor belts of the lower contact device (2) rests against a section of the rear electrode of the wafer solar cell (W), and - that the two circulating conveyor belts of the lower contact device (2) are arranged at a distance from each other when viewed perpendicular to the inline transport direction (i). [2] Plant according to one of the preceding claims, characterized by that the conveyor belts are made of a conductive film or an electrically conductive rubber. [3] Plant according to claim 1, characterized by that the conveyor belts have a conductive coating. [4] Plant according to claim 3, characterized by that the conductive coating is formed from a conductive foil, a conductive rubber, a conductive foam or a contact fleece. [5] Plant according to one of the preceding claims, characterized by that the conveyor belts of the upper contact device (1) and / or the conveyor belts of the lower contact device (2) are electrically connected to the voltage source via at least one of the two respective deflection rollers. [6] Plant according to one of the preceding claims, characterized by that at least two pulleys are spring-mounted. [7] Plant according to one of the preceding claims, characterized by that at least one of the pulleys is motor-driven. [8] Plant according to one of the preceding claims, characterized by that the distance between the circulating conveyor belts is in a range from 1 / 50 to 1 / 4, preferably from 1 / 50 to 1 / 10, more preferably from 1 / 50 to 1 / 20, of the extent of the wafer solar cell (W) along the inline transport direction (i). [9] Plant according to one of the preceding claims, characterized by that the system has a laser device which moves or projects a laser beam transversely to the inline transport direction (i) in a region formed by the spacing of the transport belts of the upper contact device (1) over a front side of the wafer solar cell and / or in a region formed by the spacing of the transport belts of the lower contact device (2) over a rear side of the wafer solar cell. [10] Inline production apparatus for a wafer solar cell (W) comprising a system according to one of the preceding claims. [11] Manufacturing method for a wafer solar cell (W) using a system according to one of claims 1 to 7 or the inline production device according to claim 10, wherein an inline transport speed of the wafer solar cells (W) along the inline transport direction (i) of 0.1 to 60 m / min, preferably of 3 to 20 m / min and particularly preferably of 6 to 20 m / min is realized.

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