Method for repairing a solar cell module

Abstract

Method for repairing a defective solder joint in a solar cell module, comprising the following steps: Detecting (S110) the defective solder joint; and Heating (S120) the defective solder joint by an induction field (200) to cause the defective solder joint to heal, wherein the solar cell module is laminated and the step of heating (S120) the defective solder joint is carried out through the laminate.

Description

[0001] The present invention relates to a method for repairing and a method for manufacturing solar cell modules and in particular to inductive soldering in the final solar module or laminate assembly. background

[0002] Solar cell modules are frequently exposed to extreme weather conditions, such as significant temperature fluctuations. The resulting thermal stresses can cause damage to the solder joints used to connect individual solar cells or to make contact. To ensure proper functioning, such defective solder joints must be identified and subsequently repaired.

[0003] In the prior art, this problem was previously solved by opening the laminate of the solar cell modules at the back – for example, by grinding and peeling off the foil stack. This approach is fundamentally unsuitable for solar cell modules formed between two glass substrates. Therefore, such solar cell modules were often completely replaced if defective solder joints were discovered.

[0004] Another option for repairing defective solder joints is the use of laser radiation. This option is applicable if the solar cell module has a laminate or backsheet that is transparent to the laser radiation. In this case, the defective solder joint can be soldered through the laminate, allowing subsequent repair without opening the solar cell module.

[0005] However, this process can only be used if the laminate or backsheet is sufficiently transparent for the laser radiation, which is not always the case. Over time, the material of the backsheet or laminate can become increasingly opaque, making this process no longer reliable. Furthermore, the laser only heats and melts a surface area, which is often insufficient to form a reliable solder joint.

[0006] Further conventional methods for repairing solder joints are disclosed in WO 2011 / 000 814 A2. Furthermore, DE 10 2010 016 976 A1 discloses a conventional method for interconnecting solar cells, and DE 10 2013 204 343 A1 discloses a conventional method for manufacturing photovoltaic modules.

[0007] Therefore, there is a need for additional ways to repair defective solder joints without damaging the solar cell module. There is also a need for a manufacturing process that allows the formation of solder joints to be performed post-process on the finished laminate. Summary

[0008] At least some of the above-mentioned problems are solved by a repair method according to claim 1. The dependent claims relate to further advantageous embodiments of the method according to claim 1.

[0009] The present invention relates to a method for repairing one or more defective solder joints in a solar cell module. The method comprises the steps of detecting the defective solder joint and heating the defective solder joint using an induction field to cause the defective solder joint to heal.

[0010] Optionally, the solar cell module is laminated and the step of heating the defective solder joint is carried out through the laminate.

[0011] The heating step may in particular be carried out by an opaque material from a back side of the solar cell module, wherein the opaque material may comprise or be a part of a film or an opaque substrate.

[0012] Optionally, the step of detecting the defective solder joint can be performed using electroluminescence to identify the defective solder joint.

[0013] Optionally, the defective solder joint can be heated by an induction field that is focused on the solar cell module and generated by a manually operated induction head.

[0014] The induction field can be generated by an induction coil through which an alternating current flows, which can be characterized by the following parameter ranges: Current: I = 3-30 A, Voltage: U = 100-400 V, Frequency: f = 40 - 1000 kHz.

[0015] The field strength generated depends on the geometric design of the coil head, which in turn can be adapted to the specific task, taking into account, for example, different thicknesses of the backing materials (plastic backing film, glass, etc.).

[0016] The present disclosure also relates to an example for manufacturing a solar cell module. The manufacturing method comprises the steps: (a) arranging a stack with at least two solar cells and connecting elements (e.g. cross connectors, cell connectors, etc.); (b) laminating the stack; and (c) Forming a solder connection between the solar cells by inductive heating.

[0017] The connecting elements include cell connectors and cross connectors. Cell connectors, for example, establish an electrical connection between the solar cells to form strings of solar cells, while cross connectors, for example, form electrical cross connections for current paths through interconnected strings of solar cells.

[0018] According to the invention, step (b) is carried out before step (c). Short description of the characters

[0019] The embodiments of the present invention will be more fully understood from the following detailed description and the accompanying drawings, which, however, should not be construed as limiting the disclosure to the specific embodiments, but are for explanation and understanding only. Fig. 1 shows a flowchart for a method for repairing a defective solder joint in a solar cell module according to an embodiment of the present invention. Fig. 2 shows an example of a flow chart for a method for producing a solar cell module. Fig. Figure 3 shows a schematic representation of an exemplary implementation of the methods. Detailed description

[0020] Fig. Figure 1 shows a flowchart for a method for repairing a defective solder joint in a solar cell module. The method comprises the following steps: - Detect S110 of the defective solder joint, and - Heating S120 of the defective solder joint using an induction field to heal the defective solder joint.

[0021] The induction field can be selected according to the solar cell module and the solder material used. Conversely, a solder material can also be specifically selected to achieve inductive heating / melting efficiently. For example, a high-frequency induction field can be introduced into the module from the outside, causing the solder to melt under the high-frequency induction field, thereby repairing the defective solder joints and closing any potential cracks in the solder material. Therefore, at least some of the technical problems mentioned above are solved by inductive healing of damaged solder joints.

[0022] In order to determine the exact location of the defective solder joint, exemplary embodiments use electroluminescence. A current is passed through the solar cells, whereupon they themselves emit light (or electromagnetic radiation in general), with the most intense light being generated where a large current flows, i.e. where the solder joints are undamaged. This current strength and thus the electroluminescence is influenced by the defective solder joints and is therefore visible. The areas where the solder joints have cracks are darker or the radiation is less intense. By detecting the radiation generated by the solar cells, the defective areas (e.g. microcracks in the solder joint) can be precisely located. Once the location of the defective solder joint has been determined, inductive fusion can be carried out specifically there.However, other methods can also be used to detect exemplary cracks in solder joints (e.g. high-precision optical analyses).

[0023] However, this approach should not be limited to repairs. Rather, the inventive concept can also be used to manufacture a solar cell module. In this case, no detection of the defective solder joints is required.

[0024] Fig. 2 shows a flowchart for an exemplary manufacturing method of a solar cell module, which includes the following steps: - arranging S210 a stack with at least two solar cells, cross connectors, cell connectors or general connecting elements; - Laminating S220 of the stack; and then - Forming S230 a solder connection between the solar cells by means of inductive heating.

[0025] The stack can contain all the components of the solar module, so that after inductive soldering, the solar cell module is fully processed. In this manufacturing process, the components of the solar cell module are first correctly positioned (optionally with a backsheet), and the stack is laminated without soldering. After lamination, the electrical connections between the components are finally soldered using the induction soldering unit. This allows a current path to be created between the solar cells and / or the transverse and longitudinal connectors after the stack has been laminated.

[0026] Fig.3 shows a schematic representation of the use of a mobile inductive soldering device 110 for soldering electrical connections in solar cell modules, as defined in the aforementioned methods. The solar cell module comprises a glass 50 on the light-facing side (front side) and a backsheet 60 on the light-remote side (rear side), between which are solar cells 52 embedded in at least one EVA film (EVA = ethylene vinyl acetate). The solar cells 52 are electrically connected to one another by cross-connectors 53 and cell connectors 54 as connecting elements. Instead of the backsheet 60, a glass substrate can also be present on the rear side. The entire stack 70 is sealed by lamination to protect it against external influences.

[0027] Any damage to or opening of the laminated stack 70 carries the risk of micro-openings remaining during resealing, which could permanently damage the entire solar cell module. Embodiments of the invention circumvent this problem by not opening the stack 70 for repair, but rather by repairing the defective solder joints using the induction soldering unit 110, which is brought into proximity with the defective solder joint. An induction field (high-frequency magnetic field) 200 is formed there, which inductively heats the solder material and, for example, repairs the defective solder joints by melting it. Embodiments thus achieve contactless formation / repair of electrical connections using induction.

[0028] In contrast to conventional repair methods, the solar cell module does not need to be opened or damaged in any way and can be immediately reinstalled after soldering (without resealing). This method is applicable regardless of whether the laminate or the backsheet 60 is / are transparent or has become cloudy over the years. In particular, it is possible to carry out the repair of the solar cell modules on-site using a mobile induction soldering unit 110, without having to uninstall the solar cell modules.

[0029] As mentioned above, in order to locate defective solder joints without damaging the solar cell module (opening the laminate), a measurement based on electroluminescence can be performed. The detected defective solder joints can then be repaired using the mobile induction soldering head 110. This process can be performed from both the glazed side and the foil side, with the electroluminescence measurements particularly allowing the detection of defective solder joints on the cross-connections.

[0030] Examples offer a number of advantages that can be summarized as follows: - Induction primarily heats only conductive parts (since no eddy currents are induced in insulating materials). In contrast, conventional soldering processes using laser beams heat all light-absorbing parts, including insulating areas. This is often undesirable. - Induction heating also offers the advantage that even deeper areas can be heated and melted very well - which would not be the case with heating using laser radiation. - Inductive heating works particularly well in areas with increased electrical resistance. For these reasons, it is not absolutely necessary to know the exact location of the defective solder joints in the examples, since microcracks in the solder joints increase the electrical resistance and these areas are heated particularly hot. - With a corresponding soldering head design, the repair of the defective solder joint can be carried out from the back (but also from the front) without first removing the frame of the solar cell module, which is not possible with a conventional repair of common module designs. - In contrast to the state of the art, the repair can be carried out on site.

Claims

[1] A method for repairing a defective solder joint in a solar cell module, comprising the following steps: Detecting (S110) the defective solder joint; and Heating (S120) the defective solder joint by an induction field (200) to cause the defective solder joint to heal, wherein the solar cell module is laminated and the step of heating (S120) the defective solder joint is carried out through the laminate. [2] The method according to claim 1, wherein the heating step (S120) is performed through an opaque material, in particular through a film or an opaque substrate from a back side of the solar cell module. [3] Method according to one of the preceding claims, wherein the step of detecting (S110) the defective solder joint is carried out by means of electroluminescence in order to identify the defective solder joint. [4] Method according to one of the preceding claims, wherein the induction field (200) is formed focused on the solar cell module by a manually operable induction head (110). [5] Method according to one of the preceding claims, wherein the induction field (200) is generated by an induction coil through which an alternating current flows with a current intensity in a range of 3 A to 30 A at a voltage in a range of 100 V to 400 V, the alternating current having a frequency in a range of 40 kHz to 1000 kHz.

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