Method and device for processing a solar module

Abstract

The invention relates to a method for processing a solar module, wherein the solar module comprises – at least one silicon main body (2) having a charge-doped zone, a hole-doped zone and a first surface and – first metallic conductor tracks (4) on the first surface of the main body (2), wherein the method comprises the following steps: a) providing a prepared solar module in which the first metallic conductor tracks (4) are accessible from outside, b) removing a removal portion of the main body (2), wherein the first metallic conductor tracks (4) are situated on the removal portion, c) collecting the removed material.

Description

[0001] Method and device for processing a solar module

[0002] The invention relates to a method for processing a solar module, wherein the solar module comprises at least one silicon base body with a charge-doped zone, a hole-doped zone, and a first surface, as well as first metallic conductor tracks on the first surface of the base body. The invention also relates to a device for carrying out such a method.

[0003] Solar modules of the above-mentioned type are being used in increasing numbers to generate electricity from sunlight. These solar modules can be installed in small numbers on private roofs, for example, on residential buildings, to at least partially cover the electricity needs of the house on which the solar modules are mounted. Such decentralized energy supplies are being used in increasing numbers, also for the decentralized charging of electric vehicles, for example. However, solar modules of the above-mentioned type are also being used in large systems on otherwise agricultural land to generate commercial electricity and feed it into the public grid.

[0004] The disadvantage is that solar modules only have a limited lifespan. Expensive raw materials are used in their production. For example, the conductive paths in a large number of modules are made of silver. For this reason alone, there is a need for a process to recycle these raw materials and make them reusable. However, the increasing number of solar modules that reach the end of their lifespan and are discarded also creates a large amount of waste that should be recycled or at least processed, especially given the environmental compatibility of power generation, which solar modules and the generation of electricity from sunlight stand for. For solar modules in which metal components are arranged on a glass substrate, JP 2014 / 054593 A proposes a process in which the components are removed mechanically.The glass described therein is able to withstand mechanical stress, which is why precisely these substrates are described and disclosed there. For other substrates, the only known methods from the prior art are wet-chemical processes, which are disadvantageous due to the high costs, the substances used, which are often harmful to the environment and / or health, and the high complexity involved.

[0005] The base body of a solar module has an upper side which, when the solar module is in operation, faces the light to be captured and is generally covered with a cover layer made of glass or another material. This cover layer is preferably transparent or at least partially transparent to the light to be captured. The base body also has an underside opposite the upper side. The underside is preferably covered with a carrier layer. This preferably means that the underside of the base body is arranged on the carrier layer. Metallic conductor tracks can be arranged on both the upper side and the underside of the base body. Metallic conductor tracks on the upper side are preferably located between the upper side of the base body and the cover layer. Metallic conductor tracks on the underside are preferably located between the underside of the base body and the carrier layer.In both cases, additional layers or materials can be arranged between the base body and the cover layer or carrier layer. This could be, for example, an adhesive layer.

[0006] The invention is therefore based on the object of proposing a method with which the disadvantages of the prior art can be eliminated or at least mitigated.

[0007] The invention solves the problem by a method of the type mentioned at the outset, which comprises the following steps: a) providing a prepared solar module in which the first metallic conductor tracks are accessible from the outside, b) removing an ablated portion of the base body, wherein the first metallic conductor tracks are located on the ablated portion, c) collecting the removed material.

[0008] Any carrier layers or covering layers, such as cover glasses or protective layers against mechanical damage, which many solar modules have, have been removed from the prepared solar module. This can be done using a process as described here. This will be described in detail later. However, it is also possible to perform this preparation not using the processes described here, but to start the process with an appropriately prepared solar module. Such a module can be purchased externally, for example.

[0009] The first surface can be the top side of the base body. In this case, the first metallic conductor tracks are the conductor tracks arranged on the top side of the base body. These can also be referred to as upper conductor tracks. However, the first surface can also be the bottom side of the base body. In this case, the first metallic conductor tracks are the conductor tracks arranged on the underside of the base body. These can also be referred to as lower conductor tracks. For the process, it is irrelevant whether upper or lower conductor tracks are considered the first conductor tracks. What is important is that the solar module is prepared in such a way that these first conductor tracks are accessible from the outside. For this purpose, a cover layer has been removed if the first conductor tracks are upper conductor tracks, and a carrier layer has been removed if the first conductor tracks are lower conductor tracks.

[0010] In a prepared solar module, the first conductor tracks are accessible from the outside. This means, in particular, that they are not covered by a solid layer, such as glass or plastic. However, it does not necessarily mean that the conductor tracks must not be covered at all, even if this is the preferred design. It is entirely possible that the conductor tracks are covered by an adhesive layer or by its remnants or parts that were required or used to attach a cover layer or a carrier layer. The important thing is simply that the conductor tracks are accessible in such a way that they can be removed with a removal tool together with the portion of the base body lying beneath the conductor tracks.

[0011] This happens in process step b). A query portion of the base body on which the first metallic conductor tracks are located is removed. The query portion therefore includes in particular the part of the first surface of the base body on which the first conductor tracks are arranged. It is important for the process that as large a portion of the first surface as possible, where there are no conductor tracks, is not removed. This increases the proportion of metal in the removed material. During the query, a small swathe or groove is made in the first surface of the base body. This usually has irregular borders and edges, since the material being removed is preferably broken out of the base body. Instead of speaking of a groove or swathe, one could also say that a depression is made in the first upper surface.The recess preferably extends along the path along which the conductor tracks were arranged on the first surface. The recess is preferably a maximum of twice as wide as the conductor track. As already explained, the first surface can be the top or bottom of the base body.

[0012] The removed material is collected and sent for further processing. This further processing takes place, for example, in a separating device in which the metal of the metallic conductor tracks is separated from the silicon of the base body, which was also removed. From an economic perspective, one is interested in the metal of the metallic conductor tracks. It is therefore advantageous to keep the proportion of silicon in the collected material as low as possible. The depth of the depression that is made in the first surface during scanning is preferably small, for example less than 1 cm, preferably less than 5 mm, particularly preferably less than 2 mm. Preferably, an removal tool is used to remove the removed portion. This tool penetrates the base body with a penetrating element and breaks out the removed portion. The removal tool is preferably a milling cutter, a wedge, or a knife.A rolling cutting tool, similar to a pizza roller used for cutting a pizza, can also be used.

[0013] It is advantageous that the removal tool has a penetrating element that penetrates the base body and thus breaks out the material to be collected. The penetrating element penetrates, for example, the first surface of the base body.

[0014] The penetrating element preferably penetrates into a side surface of the base body or through the first surface of the base body. The base body has a first surface and a second surface opposite the first surface. Between the first surface and the second surface is the side surface which connects the two surfaces. By the penetration of the penetrating element into this side surface, the depth of the depression to be produced can be easily and precisely adjusted. A penetrating element is preferably wedge-shaped, i.e. has an increasing thickness in at least one direction. The penetrating element then preferably penetrates the base body with a thin side, i.e. with a small thickness. As the thickness of the penetrating element increases, it breaks material out of the base body and moves this material upwards.

[0015] In a preferred embodiment, the removal tool has two penetration elements, each of which penetrates the base body on one side of the metallic conductor tracks, so that the removal portion lies between the two penetration elements. In this embodiment, it is advantageous, but not necessary, for the penetration elements to penetrate the first surface of the base body. Particularly preferably, the two penetration elements extend conically toward each other in the penetration direction. The distance between the two penetration elements thus decreases with increasing penetration depth. This makes it particularly easy to break out the material of the base body lying between them.

[0016] Advantageously, the base body has a second surface opposite the first surface, on which second metallic conductor tracks are located, wherein the interrogation portion includes a portion of the first surface with the first metallic conductor tracks and a portion of the second surface with the second metallic conductor tracks. This increases the metal yield and makes the process more economical. If the top side of the base body forms the first surface, then the second surface is the underside of the base body, and vice versa.

[0017] Preferably, the first metallic conductor tracks and the second metallic conductor tracks are located opposite one another. This means that the depression to be introduced during the interrogation extends through the entire base body, i.e., from the first surface to the second surface, and in this way, both the first conductor tracks and the second conductor tracks are removed. This does not mean that second conductor tracks are also arranged on the second surface wherever first conductor tracks are located on the first surface. However, first conductor tracks are preferably positioned opposite one another on the first surface at the locations where second conductor tracks are located on the second surface of the base body.

[0018] Preferably, there are fewer second conductive paths on the second surface than first conductive paths on the first surface. Even in the case of lateral penetration, if the tip of the penetrating element does not necessarily penetrate the base body, but rather also penetrates, for example, the second conductive paths or a layer lying below it, such as a carrier layer or a cover layer, the penetrating element is referred to in the context of the present invention as penetrating the base body.

[0019] Advantageously, the second conductor tracks are covered by a carrier layer, preferably made of plastic. This carrier layer may be damaged during the interrogation of the interrogation portion, so that material from the carrier layer is also present in the collected material. The carrier layer ensures that the solar module does not break or that the remaining parts of the solar module do not separate from each other, even if the recess created in the base body during removal completely divides the base body.

[0020] In a preferred embodiment, the solar module has a cover layer that is at least partially transparent to visible light, preferably transparent to visible light, and at least one adhesive layer that is arranged between the cover layer and the first metallic conductor tracks, wherein the provision of the prepared solar module includes heating the at least one adhesive layer and the subsequent removal of the cover layer from the base body.

[0021] The adhesive layer is preferably heated by means of infrared radiation and / or magnetic induction and / or microwave radiation. The heating takes place to a temperature of more than 180°C, preferably more than 200°C, more preferably more than 230°C and less than 400°C, preferably less than 350°C, and particularly preferably less than 280°C. Particularly when using infrared or microwave radiation, it is advantageous to apply the radiation through the cover layer, which is preferably at least partially, but preferably completely, transparent to the respective type of radiation. Infrared radiation used for this purpose preferably has a wavelength of 1000 to 4000 nm, preferably 2000 to 2500 nm. The preferred temperature is below 400°C. Above this temperature, pyrolysis occurs, during which some toxic and environmentally harmful gases are released.This can be avoided by using a temperature below 400°C. At temperatures above 180°C, preferably above 200°C, acetic acid is released, preferably in the adhesive layer, creating a lubricating film between the layers bonded by the adhesive layer, i.e., preferably the base body and the cover layer. This reduces the adhesive forces exerted by the adhesive layer, and the two bonded elements can be separated. Preferably, at least one film made of ethylene-vinyl acetate (EVA) is used as the adhesive layer, which releases acetic acid when heated within the specified temperature range.Once the adhesive layer has been heated to the desired temperature, a heat source can either be switched off or controlled so that the temperature is kept constant for a certain period of time, for example 10 minutes, in order to process the solar module at this adhesive layer temperature. Heating is preferably carried out over the entire surface so that the entire adhesive layer of the solar module to be processed is heated evenly. Alternatively, it is also possible to heat part of the adhesive layer and, for example, move the heat source relative to the solar module or vice versa. During heating, the solar module is preferably in a vacuum, i.e., subjected to low pressure. However, heating under normal pressure is also possible.

[0022] If electromagnetic radiation is used as the heat source, it can be introduced directly into the adhesive layer to be heated through the cover layer, which is at least partially transparent to this radiation. This is different when magnetic induction is used as the heat source, as the adhesive layer is generally not magnetic or magnetizable. In this case, the magnetic induction field heats another layer of the solar module, preferably the base body, which can also be called a substrate or wafer, so that it then transfers heat to the adhesive layer arranged on top of it.

[0023] Lasers can also be used in addition to or alternatively to the heat sources mentioned to heat the at least one adhesive layer.

[0024] In a preferred embodiment, the cover layer is removed from the base body by applying opposing tensile forces to the cover layer and the base body. The opposing tensile forces can be applied perpendicular to the top side of the base body. For a solar module lying on a work surface, this means that the tensile forces act upwards and downwards. Vacuum elements, for example suction elements, are preferably used for this purpose. The substrate is preferably positioned on a work surface which has openings which are then closed by the substrate. By applying a vacuum or a suction force to the closed openings, a suction force and thus a tensile force is exerted on the substrate, which holds it to the work surface.Preferably, at least one suction element or at least one suction gripper is arranged on the cover layer, which is designed to apply a suction force to the cover layer directed away from the work surface, i.e., generally acting upwards. This applies two opposing forces and separates the cover layer from the substrate.

[0025] Alternatively or additionally, a force acting parallel to the work surface on which the substrate is arranged is applied to the cover layer by at least one slider. The substrate is preferably held against the work surface by the suction force already described. Alternatively or additionally, the work surface has a stop which protrudes from the work surface and against which the substrate rests. The substrate rests against the stop in such a way that any movement of the substrate which would be caused by the force applied by the slider is prevented and is not possible. If the slider applies a force to a first side surface of the cover layer, the substrate preferably rests against the projection with the opposite side surface.

[0026] Alternatively, the opposing tensile forces can also be applied parallel to the top of the base body. This creates shear forces that separate the two components.

[0027] In a preferred embodiment, the cover layer is damaged or destroyed before heating the adhesive layer or before removing the cover layer from the base body. The cover layer is preferably divided into several parts by mechanical stress. This can be done, for example, by striking the cover layer with a hammer. The cover layer is then present in several individual parts, most of which, preferably all of which, are still connected to the base body via the adhesive layer. These individual parts can then be removed from the base body in the ways already described.

[0028] If the cover layer and the base body are separated in such a way that they are moved parallel, little bending moment is applied, especially to the base body, on whose upper surface the conductor tracks are located, thus reducing the risk of the base body breaking. This is advantageous because the conductor tracks are mechanically removed from the base body, which is easier the less mechanically damaged the base body is.

[0029] Preferably, before removing the cover layer, the cover layer is damaged using a tool, preferably a spatula, scraper, knife, or wire, whereby the tool is preferably inserted between the cover layer and the base body. Unlike the base body, which is preferably undamaged and free of fractures after removal from the cover layer, the cover layer is damaged to facilitate the removal of individual parts of the cover layer.

[0030] Preferably, when removing the cover layer, the at least one adhesive layer is also removed at least partially, but preferably completely. This ensures that as few portions of the adhesive layer as possible remain on the upper side of the base body and thus on the conductor tracks. These portions would be removed when the interrogation portion is removed and collected with the removed material.

[0031] Preferably, the adhesive layer is therefore removed at least partially, but preferably completely, after the removal of the cover layer. It may be advantageous to reheat the remaining portions of the adhesive layer if the adhesive layer no longer has sufficient heat. Particularly preferably, a mechanical tool, such as a wire, a spatula, a scraper, a blade, a knife, or a brush, is used to remove the at least one adhesive layer after the removal of the cover layer.

[0032] The removed material is collected. It is preferably vacuumed and collected in a container. It is advantageous if the tool used for removal is already inside a box or bell jar so that the removed dust can be collected as easily as possible. The material can be collected with a stream of air or a stream of liquid, such as water or oil. However, liquid is preferably not used, as the removed chips or dust must be dried later.

[0033] The invention achieves the stated object by means of a device for carrying out a method described herein, which device comprises a removal tool and a collecting device. Preferably, the device has at least one heating device for heating the at least one adhesive layer and at least one pulling device for exerting a pulling force. The pulling device preferably has at least one, preferably several, vacuum grippers and / or at least one, but preferably several, Bernoulli grippers.

[0034] In a preferred embodiment, the device also has an electrical control and the removal tool has at least one mechanical tool, wherein the electrical control is configured to control at least one operating parameter of the at least one mechanical tool.

[0035] The at least one operating parameter is preferably a contact pressure, a displacement, or a force. The electrical control is preferably an electronic data processing device, which is preferably part of the device. However, it is also sufficient if the electronic data processing device is not part of the device, but rather the device communicates with the electronic data processing device via a communication device. An embodiment of the present invention is explained in more detail with the aid of the attached drawing. It shows:

[0036] Figure 1 - the schematic representation of a solar module with

[0037] Removal tool and collection device.

[0038] Figure 1 shows a prepared solar module. It has a base body 2, on whose first surface first conductor tracks 4 are located. Second conductor tracks 6 are shown on the opposite second surface.

[0039] In the exemplary embodiment shown, a carrier layer 8 is located underneath. In the exemplary embodiment shown, the first surface of the base body is the top side of the base body. In the exemplary embodiment shown, the second surface of the base body is the underside of the base body. This is advantageous, but not necessary. In order to be able to recycle the first conductor tracks 4 and the second conductor tracks 6, the illustrated penetrating element 10 of a removal tool will penetrate into the base body. In the exemplary embodiment shown, this occurs in such a way that the penetrating element penetrates between the second conductor track 6 and the carrier layer 8 and, due to its wedge shape, breaks up the layers above and thus removes them. The material thus removed is collected by a suction device 12 and fed for further processing.

[0040] List of reference symbols

[0041] 2 basic bodies

[0042] 4 first conductor tracks

[0043] 6 second conductor tracks

[0044] 8 Carrier layer

[0045] 10 Penetrating element

[0046] 12 Extraction

Claims

Patent claims 1. A method for processing a solar module, wherein the solar module - at least one silicon base body (2) with a charge-doped zone, a hole-doped zone and a first surface and - has first metallic conductor tracks (4) on the first surface of the base body (2), the method comprising the following steps: a) providing a prepared solar module in which the first metallic conductor tracks (4) are accessible from the outside, b) removing an ablated portion of the base body (2), the first metallic conductor tracks (4) being located on the ablated portion, c) collecting the removed material.

2. Method according to claim 1, characterized in that for removing the removal portion, a removal tool is used which penetrates into the base body (2) with a penetrating element (10) and breaks out the removal portion.

3. Method according to claim 2, characterized in that the penetration element (10) penetrates into the base body (2) on a side surface of the base body (2) or through the first surface of the base body (2).

4. Method according to claim 2 or 3, characterized in that the removal tool has two penetration elements (10) which penetrate into the base body (2) on one side of the first metallic conductor tracks (4) in each case, so that the removal portion lies between the two penetration elements (10). Method according to one of the preceding claims, characterized in that the base body (2) has a second surface opposite the first surface, on which second metallic conductor tracks (6) are located, wherein the removal portion includes a part of the first surface with the first metallic conductor tracks (4) and a part of the second surface with the second metallic conductor tracks (6). Method according to claim 5, characterized in that the first metallic conductor tracks and the second metallic conductor tracks (6) lie opposite one another. Method according to one of the preceding claims, characterized in that the first or second metallic conductor tracks (6) are covered by a carrier layer (8), preferably made of a plastic.Method according to one of the preceding claims, characterized in that the solar module has a cover layer that is at least partially transparent to visible light, preferably transparent to visible light, and at least one adhesive layer arranged between the cover layer and the first or second metallic conductor tracks (6). Providing the prepared solar module includes heating the at least one adhesive layer and subsequently removing the cover layer from the base body (2). A device for carrying out a method according to one of the preceding claims, comprising a removal tool and a collecting device.

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