Apparatus and method for improving ohmic contact between front contact grid and doped layer of a crystalline solar cell

Abstract

The invention relates to a device for improving the ohmic contact between the front contact (14) and the doped layer of a wafer solar cell (1) having a front side (11), a back side (12), a front contact (14) and a back contact (15) in the form of strips or grids, the device having: - two contact means (6) for electrical contact with the front contact (14) and the back contact (15), - a voltage source (7) having one pole electrically connected to one contact means (6) and the other pole electrically connected to the other contact means (6), - two point light sources (4), one of which is used to illuminate the front side (11) and the other of which is used to illuminate the back side (12), wherein the contact means (6) each comprise: · An optically transparent material coated with an optically transparent conductive layer, · An optically transparent material (62) having a surface integrated with a plurality of fine conductive lines (61), · An optically transparent conductive material having a surface integrated with a plurality of fine conductive lines, · A woven or mesh structure (61) composed of a plurality of fine conductive lines. The invention also relates to a method for improving the ohmic contact between the front contact (14) and the doped layer of the wafer solar cell (1) using the device.

Description

Technical Field

[0001] This invention relates to a method for improving the ohmic contact between the front contact grid and the doped layer of a crystalline solar cell. The front side of the crystalline solar cell represents the side facing the sun when the crystalline solar cell is operating, while the back side of the crystalline solar cell represents the side facing away from the sun when the crystalline solar cell is operating. Background Technology

[0002] In the production of crystalline solar cells with a doped emitter layer and a front contact grid, high contact resistance can occur at the transition between the metal paste provided for producing the front contact grid and the doped layer, depending on the specific process control. This high contact resistance typically leads to a reduction in the efficiency of the crystalline solar cell.

[0003] DE102016009560A1 and DE102018001057A1 disclose methods for improving the ohmic contact between a front contact gate and a doped layer designed as an emitter layer. First, a doped layer, a front contact gate, and a back contact gate are formed on a crystalline solar cell. Then, the front contact gate is electrically connected to one pole of a voltage source, and a contact device electrically connected to the other pole of the voltage source is connected to the back contact gate. The voltage source is used to apply a voltage opposite to that of the crystalline solar cell, the magnitude of which is lower than the breakdown voltage of the crystalline solar cell. When the voltage is applied, a point light source is directed to the sun-facing side of the crystalline solar cell. A segment of a localized area on the sun-facing side is illuminated, thereby inducing a current in that segment of the localized area. The current density is 200 A / cm². 2 Up to 20,000 A / cm 2 Between these two points, the duration of the effect on this segment is 10ns to 10ms.

[0004] This method achieves localized and subsequent improvements in the contact resistance of crystalline solar cells by applying a reverse voltage and localized illumination. A large current flows through a small area, improving the metal-semiconductor contact at that location. To apply the voltage, the crystalline solar cell must be in contact on both sides. Furthermore, the contact device is often located in the optical path of a point light source, thus in areas where the contact device is, for example, an opaque, strip-shaped region, it is either impossible or only partially functional.

[0005] Figure 1 This is a cross-sectional view of a known device according to prior art (DE102016009560A1). The crystalline solar cell 1 has a front side 11 and a back side 12. The front side 11 has a front contact 14, and the back side 12 has a back contact 15. The front contact 14 and / or the back contact 15 are in the form of strips or grids. The device also has:

[0006] - A contact device 3 for making electrical contact with the front contact 14, the contact device 3 is configured with four parallel wires, one of which is shown in the cross-sectional view. Figure 1 ,

[0007] - Another contact device 2 for making electrical contact with the back contact 15, the other contact device 2 having a conductive material that completely covers the back contact 12 during electrical contact and is optically opaque.

[0008] - Voltage source 7, one pole of which is electrically connected to contact device 3, and the other pole of which is electrically connected to another contact device 2, and

[0009] - A point light source 4, which is configured to illuminate the front side 11 of the crystalline solar cell 1.

[0010] In existing methods, the front contact 14 is in electrical contact with the contact device 3, and the back contact 15 is in electrical contact with another contact device 2. Furthermore, a voltage is applied by the voltage source 7 to generate a reverse current, and the point light source 4 is directed to the front surface 11, thereby partially illuminating a portion of the front surface 11 with the beam 5.

[0011] However, in this method, the current passing through the front contact 14 experiences significant voltage loss along the path. Furthermore, the contact device 3, consisting of four wires, can obstruct the point light source 4, and there is a risk of damage to the crystalline solar cell 1 due to mechanical interactions. Additionally, the wires may burn out due to the very large local current generated in the so-called shunt.

[0012] Figures 2a to 2c This is a cross-sectional view of another prior art device that employs a method to improve the ohmic contact between the front contact grid and the doped layer of a crystalline solar cell. Figure 2a This is a cross-sectional view of the device, and... Figure 1 The corresponding device is shown, except that contact device 3 does not have four wires, but rather two opposing conductive strips, and for clarity, the voltage source is not shown. Figure 2a As shown, one of the two conductive strips is in contact with the front contact 14, while the other is not in contact with the front contact 14 because the point light source 4 is guided to a portion of the front contact 14 and moves on the front of the crystalline solar cell 1. This prevents shading of the illuminated section. Then, the other conductive strip is connected to the opposite side of the first conductive strip, while simultaneously guiding the point light source 4 to the center of the crystalline solar cell 1. Then, one conductive strip is removed, thus... Figure 2c In the middle, originally in Figure 2aThe shaded portion of the epitaxial solar cell 1 can still be illuminated by the point light source 4. This electrical contact method results in significant voltage loss due to the current flowing through the front contact 14 to the illuminated operating point. The current at the edge of the epitaxial solar cell 1 must flow through the entire front contact 14 to the conductive strip on the opposite side. Therefore, the voltage applied to the illuminated operating point is unevenly distributed on the surface of the epitaxial solar cell 1, thus failing to uniformly act on the front side of the epitaxial solar cell 1. Furthermore, the conductive strip is not redundant. If the conductive strip fails to make proper contact with the front contact 14, the cell will not function.

[0013] It is evident that shading of the crystalline solar cell by the contact device can cause problems. As the contact passes through the solar cell, some voltage drops due to resistance. Consequently, the effective processing parameters differ between contacts closer to and farther from the contact device. This results in an uneven distribution of the applied reverse voltage on the front of the crystalline solar cell, severely impacting its proper operation and ultimately reducing its efficiency.

[0014] Furthermore, WO2017 / 175491A1 describes a method for manufacturing a series-connected battery, which includes a first solar cell and a second solar cell having a first electrode. In this method, a reverse voltage is applied between a region of the first electrode and the second solar cell, while simultaneously applying a reverse voltage to the second solar cell and irradiating it. Summary of the Invention

[0015] The objective of this invention is to provide an apparatus and method for improving the ohmic contact between the front contact and the doped layer of a crystalline solar cell. This apparatus and method can prevent or at least reduce shading and achieve more homogeneous operational control, thereby improving the efficiency of the crystalline solar cell.

[0016] According to the present invention, the above-mentioned task can be solved by an apparatus having the technical features of claim 1 and a method having the technical features of claim 6. Preferred improvements and modifications of the present invention are given in the dependent claims and are described below.

[0017] In each solar cell contact, the reverse current reaches the point where the point light source produces the light spot with little or no loss, because the path to that point is very short.

[0018] This device and method provide a fully conductive and transparent pressure plate on the surface of a crystalline solar cell to be irradiated. To avoid large-area shading of the point light source, a transparent pressure plate with an electrical conductor, such as an adhesive or embedded type, or an open electrical conductor grid unfolded on one side of the crystalline solar cell to prevent large-area shading, is provided as a contact device. This allows the front and back contacts of the crystalline solar cell to be electrically contacted and simultaneously irradiated. In this way, the reverse current path is always shorter, and each contact of the corresponding contact grid can be optimized. Furthermore, the solar cell is already electrically contacted with the contact device before irradiation; therefore, the interlayer formed by the crystalline solar cell and the two contact devices can be irradiated instantaneously without time delay.

[0019] The contact devices are preferably optimized for low voltage loss. Since the two contact devices are located on opposite sides of the crystalline solar cell and offset from each other, irradiation occurs from both sides, but preferably not at the same point. Sections of the crystalline solar cell shaded on one side are preferably treated by irradiation from the other side. This avoids voltage loss and the creation of untreated areas due to shadows. With an increased number of contacts, the layout of the front and back contacts becomes more flexible. Circuit breaking in the contacts can be implemented similarly to contact fingers and current collectors (e.g., busbars). Furthermore, the fault redundancy of the front and back contacts is higher. Another advantage of this contact method is that the contact devices can also function as units and can operate in cycles, which is particularly advantageous.

[0020] This invention relates to an apparatus for improving the ohmic contact between the front contact and the doped layer of a crystalline solar cell, the crystalline solar cell having:

[0021] The structure consists of a front side, a back side, a front contact, a doped layer, and a back contact, wherein the front and back contacts are in the form of strips or grids.

[0022] The device includes:

[0023] - Two contact devices, one for electrical contact with the front contact and the other for electrical contact with the back contact.

[0024] - A voltage source, one pole of which is electrically connected to one of the contact devices, and the other pole of which is electrically connected to another contact device.

[0025] - Two point light sources, one used to illuminate the front of the crystalline solar cell, and the other used to illuminate the back of the crystalline solar cell.

[0026] According to the present invention, the contact device includes:

[0027] • Optically transparent materials coated with an optically transparent conductive layer, or

[0028] • Optically transparent material, wherein multiple fine conductive lines are integrated on the surface of the optically transparent material, or

[0029] • Optically transparent conductive material, wherein the surface of the optically transparent conductive material is integrated with multiple fine conductive lines, or

[0030] • A braided or mesh structure composed of multiple fine conductive wires.

[0031] Another option for the contact device is one whose entire surface is optically transparent and conductive, thus completely or minimally reducing the negative impacts caused by light shielding and voltage losses during the flow to the irradiated working point. The improved contact device is designed and configured for electrical contact of the front or back contact body. In this invention, optically transparent material refers to a material with a transmittance of at least 90% in a wavelength range of 400 to 1,500 nm.

[0032] Another construction option for the contact device includes the use of fine conductive wires. These fine conductive wires are characterized by a diameter of less than 1 millimeter. The diameter of these conductive wires is preferably less than 500 micrometers, and most preferably less than 200 micrometers. For conductive wires of this diameter, the illumination area of ​​a point light source will be significantly larger than the diameter of the conductive wire. Due to the use of such fine conductive wires, the corresponding contact device is macroscopically optically transparent.

[0033] The aforementioned apparatus and method provide an optically transparent, or at least macroscopically optically transparent, all-conductive pressure plate for the contact members on the irradiated side of a crystalline solar cell. This allows the front or back contacts of the crystalline solar cell to be electrically contacted while the corresponding solar cell surface, previously shielded by the contact device, is also irradiated. This ensures that the reverse current, which has a significant thermal effect, always has a shorter path, minimizing voltage loss. Thus, each contact of the corresponding contact grid is optimized under very similar operating parameters. Furthermore, since the crystalline solar cell is already electrically contacted with the contact device before irradiation, the interlayer consisting of the crystalline solar cell and the two contact devices can be irradiated immediately without delay, thereby saving production time.

[0034] In a preferred embodiment, the optically transparent material coated with the optically transparent conductive layer is configured as an optically transparent material in the form of glass or plastic coated with an optically transparent conductive oxide coating. The conductive oxide can be a TCO (transparent conductive oxide), such as ITO (indium tin oxide) or ZnO:Al. This allows for full-surface electrical contact of the front or back contacts while ensuring that the side of the crystalline solar cell that makes electrical contact with the improved contact device is also illuminated.

[0035] Optically transparent materials are preferably glass or transparent plastics. Optically transparent conductive materials are preferably made of TCO, such as ITO or ZnO:Al.

[0036] The multiple conductive wires are preferably arranged in parallel to each other and embedded in the surface of the transparent material as a grid-like or braided structure. In this way, while ensuring sufficient transparency required for point light source illumination, full-surface electrical contact of the front or back contact can be achieved.

[0037] In a preferred embodiment, the plurality of fine conductive wires are made of metal and / or metal alloys. Preferably, the plurality of fine conductive wires are made of semi-noble metals and / or noble metals, such as silver wire, gold wire, or copper wire.

[0038] Preferably, both the front and back contacts have fingers arranged parallel to each other, with the width of the fingers parallel to the surface of the solar cell and perpendicular to the extension direction of the fingers. Preferably, the width of the fine conductive lines among the multiple conductive lines is smaller than the width of the fingers. This further ensures minimal shading.

[0039] For example, a point light source can be a focused beam from a laser, a light-emitting diode, or a flash lamp. The wavelength of the beam emitted by the point light source is preferably in the range of 400 nm to 1500 nm. Preferably, the point light source is a laser, particularly a laser diode.

[0040] The present invention also relates to a method for improving the ohmic contact between the front contact and the doped layer of a crystalline solar cell using the apparatus according to one or more of the above embodiments, comprising the following steps:

[0041] a) The front contact is in electrical contact with one contact device, and the back contact is in electrical contact with another contact device.

[0042] b) Apply a voltage opposite to that of the crystalline solar cell to the front and back contacts using a voltage source. The magnitude of the applied voltage is lower than the breakdown voltage of the crystalline solar cell.

[0043] c) During the application of voltage, one point light source is directed to the section facing the sun and the other point light source is directed to the section facing away from the sun. The distance between the front section and the back section is less than 5 mm, preferably less than 3 mm, so that current is generated in these sections and acts on these sections.

[0044] To avoid light shading, contact units that are close to each other on the front or back of the contact body are preferably electrically contacted alternately with the corresponding contact device on the front or back. In this way, when voltage is applied and irradiation is performed, the heating reverse current always has a very short path, and each contact of the front contact body can be optimized by irradiating the side not blocked by the operating point.

[0045] In a preferred embodiment, steps a) through c) are performed statically in the apparatus. This method is applicable to both static implementation and individual crystalline solar cell processing.

[0046] Preferably, the apparatus for improving the ohmic contact between the front contact and the doped layer of the crystalline solar cell is configured as a component of the inline crystalline solar cell production facility. Step a) includes loading the crystalline solar cell into the contact device, for example, from a loading conveyor belt, and contacting both sides of the crystalline solar cell with each contact device. Between steps a) and c), using the contact device as a transport unit, the crystalline solar cell is transported from the loading / contact area of ​​the apparatus for improving the ohmic contact between the front contact and the doped layer (where step a) is performed) to the irradiation area (where steps b) and c) are performed), and then to the unloading area (where the contact device and the crystalline solar cell are spatially separated). Finally, the crystalline solar cell is unloaded onto the unloading conveyor belt. The cycle time of this method is shortened.

[0047] Preferably, the contact device, as a component of the inline production facility, which improves the ohmic contact between the front contact and the doped layer of the crystalline solar cell, moves together with the electrically contacted crystalline solar cell in the inline transport loop, from the loading / contact area through the irradiation area to the unloading area, and then back to the loading / contact area via a return loop. Thus, two contact devices are guided in one cycle or loop process. After unloading, they are sent back outside the operating area for reloading. This further significantly reduces the cycle time. The contacting, handling, and unloading of the crystalline solar cell are not completed in one cycle, but are performed in steps. Each step is executed within one cycle.

[0048] This method is preferably executed with the following parameters:

[0049] A reverse voltage, ranging from 1 to 40V, is applied to the front and back contact gates by a voltage source. The power density of the localized irradiation is preferably between 200 and 500,000 W / cm². The process preferably involves a current of 0.1 to 10A flowing between the front and back contacts.

[0050] Preferably, prior to implementing the method of the present invention, the contact resistance of the provided crystalline solar cell, measured using the TLM method (transfer length method), is >50 mΩ·cm². In a preferred embodiment, prior to implementing the method of the present invention, the contact area of ​​the provided crystalline solar cell is less than 0.1%. That is, the metallized area of ​​the metal semiconductor contact is less than 0.1% of the surface on which the metal semiconductor contact is located. The provided crystalline solar cell preferably has one or more passivation layers and / or antireflective layers. The thickness of the antireflective layer is preferably greater than 100 nm. For example, the antireflective layer can be made of SiN. x(Silicon nitride) is formed. The antireflective layer can also be made of SiN. x (Silicon nitride) / SiO x N y (Silicon oxynitride) bilayer, or SiN x (Silicon Nitride) / SiO x N y The silicon oxynitride (SiO2) / SiO2 (silicon dioxide) three-layer structure is formed, with a thickness greater than 100 or 110 nm. Preferably, the sheet resistance of the front doped layer of the provided crystalline solar cell is higher than that of the back doped layer.

[0051] The crystalline solar cell using this method can be a single solar cell, a multi-junction solar cell, or a sub-cell of a multi-junction solar cell. Attached Figure Description

[0052] Other advantages and features of this method will be described through the preferred embodiments described below. However, the accompanying drawings are not drawn to scale and are for illustrative purposes only.

[0053] In a illustrative manner rather than to scale:

[0054] Figure 1 It is a cross-sectional view of a device based on existing technology;

[0055] Figures 2a-2c These are cross-sectional views of another apparatus for implementing the existing technical method;

[0056] Figure 3 This is a cross-sectional view of the apparatus described in the first embodiment of implementing one step of the method of the present invention;

[0057] Figure 4 This is a cross-sectional view of the apparatus described in the second embodiment of implementing one step of the method of the present invention;

[0058] Figure 5 This is a cross-sectional view of the apparatus described in the third embodiment of implementing one step of the method of the present invention;

[0059] Figure 6 This is a perspective view of the apparatus described in the fourth embodiment of the method of the present invention.

[0060] List of reference numerals

[0061] T conveying direction

[0062] Z1 Loading / Contact Area

[0063] Z2 irradiation area

[0064] Z3 Uninstallation Area

[0065] Z4 return loop

[0066] 1 Epistar Solar Cell

[0067] 11 front

[0068] 12 Back

[0069] 14 frontal contact bodies

[0070] 15 Backside Contacts

[0071] 2 Contact device

[0072] 3 Contact device

[0073] 4-point light source

[0074] 5 beams

[0075] 6 contact devices

[0076] 61 conductive wire

[0077] 62 transparent areas

[0078] 7 voltage sources Detailed Implementation

[0079] Figure 1 A cross-sectional view of an apparatus according to the prior art is shown; Figures 2a-2c Cross-sectional views of another apparatus according to the prior art are shown, implementing methods known in the prior art. Please refer to the description of these figures above.

[0080] Figure 3 A cross-sectional view of the apparatus described in a first embodiment of implementing one step of the method of the present invention is shown. Figure 3 The device shown is Figure 1 The device shown corresponds to the one shown, except that, Figure 3 The device shown does not have contact devices 2 and 3, but rather contact device 6. Contact device 6 has an optically transparent conductive layer coated on its optically transparent material. A point light source 4 illuminates a section of the front side 11 with a beam of light 5, and another point light source 4 partially illuminates another section of the back side 12 with a beam of light 5. Simultaneously, a voltage opposite to that of the crystalline solar cell 1 is applied to the front contact 14 and the back contact 15 through a voltage source 7, contact device 2, and the other contact device 6. This voltage is lower than the breakdown voltage of the crystalline solar cell 1, and the distance between the partial sections of the front side and the partial sections of the back side is less than 5 millimeters, thereby generating current in these partial sections and acting on them.

[0081] Figure 4 A cross-sectional view of the apparatus described in a second embodiment of implementing one step of the method of the present invention is shown. Figure 4 The device shown is Figure 3Corresponding to the illustrated device, the difference lies in that each contact device 6 employs an optically transparent material 62, the surface of which is integrated with multiple fine conductive lines 61. When a reverse current is generated, the point light source 4 moves along the direction of the arrow on the front side 11 or the back side 12.

[0082] Figure 5 A cross-sectional view of the apparatus described in a third embodiment of implementing one step of the method of the present invention is shown. Figure 5 The device shown is Figure 4 The device shown is different in that each contact device 6 has a braided or mesh structure composed of multiple fine conductive wires 61.

[0083] Figure 6 A perspective view of the apparatus described in the fourth embodiment of the method of the present invention is shown. This apparatus for improving the ohmic contact between the front contact and the doped layer of a crystalline solar cell is configured as a component of the inline production facility for the crystalline solar cell 1, and is used to improve the front contact of the crystalline solar cell 1 (…). Figure 6 The ohmic contact between the front contact (not shown in the figure) and the doped layer (not shown in the figure) and the back contact (not shown in the figure) of the crystalline solar cell 1 has a front contact, a doped layer and a back contact (not shown in the figure). Figure 6 (Not shown in the image), the front and back contacts are respectively designed as strips or grids. The device has two contact devices 6 for electrical contact with the front and back contacts, and a voltage source (…). Figure 6 (Not shown in the image), one electrode is used for electrical connection with one contact device 6, and the other electrode is used for electrical connection with another contact device 6. There are also two point light sources 4, one of which is configured to illuminate a portion of the front side of the crystalline solar cell 1 with a beam 5, and the other of which is configured to illuminate a portion of the back side of the crystalline solar cell 1 with a beam 5. Each of these contact devices 6 has an optically transparent material coated with an optically transparent conductive layer, or an optically transparent material (not shown) with multiple fine conductive lines (not shown) integrated on its surface, or a braided or mesh structure composed of multiple fine conductive lines (not shown). The device for improving the ohmic contact between the front contact and the doped layer of the crystalline solar cell also includes a loading / contact area Z1, an illumination area Z2, an unloading area Z3, and a return loop Z4.

[0084] In the loading / contact zone Z1, the crystalline solar cell 1 is loaded into the contact device, with the front contact making electrical contact with another contact device 6 and the back contact making electrical contact with contact device 2. Then, the contact device 6 is used as a transport device for the crystalline solar cell 1, transporting the sandwich consisting of the crystalline solar cell 1 and the two contact devices 6 from the loading / contact zone Z1 to the irradiation zone Z2. In the irradiation zone Z2, a voltage opposite to that of the crystalline solar cell 1 is applied to the front and back contacts via a voltage source. The applied voltage is lower than the breakdown voltage of the crystalline solar cell 1. Simultaneously, a point light source 4 is guided to the front or back contact, irradiating it locally and generating current in a specific section, acting on that section. Next, the sandwich is transported to the unloading zone Z3, where the contact devices 6 and the crystalline solar cell 1 are spatially separated. Then, the two contact devices 6 are returned to the loading / contact zone Z1 in the return loop Z4 for reloading.

[0085] The contact device 6, together with the electrically contacted crystalline solar cell 1, moves in an online transport cycle from the loading / contact area Z1 through the irradiation area Z2 to the unloading area Z3, and then back to the loading / contact area Z1 through the return loop Z4, thereby forming a circulating system suitable for inline mass production.

Claims

1. An apparatus for improving the ohmic contact between the front contact (14) and the doped layer of a crystalline solar cell (1), the crystalline solar cell (1) having: The front side (11), the back side (12), the front contact (14), the doped layer, and the back contact (15) are designed as strips or grids. Its features are, The device includes: - Two contact devices (6), one for making electrical contact with the front contact (14) and the other for making electrical contact with the back contact (15). - A voltage source (7), one pole of which is electrically connected to one of the contact devices (6), and the other pole of which is electrically connected to another contact device (6). - Two point light sources (4), one of which is configured and designed to illuminate the front (11) of the crystalline solar cell (1), and the other of which is configured and designed to illuminate the back (12) of the crystalline solar cell (1). The irradiation occurs from both sides of the crystalline solar cell, but not at the same point. A section of the crystalline solar cell shaded on one side is treated by irradiation from the other side. The contact devices (6) all have: • Optically transparent materials coated with an optically transparent conductive layer, or • Optical transparent material (62), wherein multiple conductive lines (61) are integrated on the surface of the optical transparent material (62), or • A braided or mesh structure composed of multiple conductive wires (61).

2. The apparatus according to claim 1, characterized in that, Optically transparent materials coated with an optically transparent conductive layer are defined as transparent materials in the form of glass or plastic coated with an optically transparent conductive oxide coating.

3. The apparatus according to claim 1, characterized in that, Multiple conductive wires (61) are arranged in parallel to each other and embedded in the surface of the transparent material (62) as a grid or braided structure.

4. The apparatus according to any one of claims 1 or 3, characterized in that, The multiple conductive wires (61) are made of metal and / or metal alloys.

5. The apparatus according to any one of claims 1 and 3, characterized in that, The front contact (14) and the back contact (15) each have a finger that is parallel to each other. The width of the finger is parallel to the surface of the solar cell and perpendicular to the extension direction of the finger. The width of each of the multiple conductive lines (61) is smaller than the width of the finger.

6. The apparatus according to claim 4, characterized in that, The front contact (14) and the back contact (15) each have a finger that is parallel to each other. The width of the finger is parallel to the surface of the solar cell and perpendicular to the extension direction of the finger. The width of each of the multiple conductive lines (61) is smaller than the width of the finger.

7. An apparatus for improving the ohmic contact between the front contact (14) and the doped layer of a crystalline solar cell (1), the crystalline solar cell (1) having: The front side (11), the back side (12), the front contact (14), the doped layer, and the back contact (15) are designed as strips or grids. Its features are, The device includes: - Two contact devices (6), one for making electrical contact with the front contact (14) and the other for making electrical contact with the back contact (15). - A voltage source (7), one pole of which is electrically connected to one of the contact devices (6), and the other pole of which is electrically connected to another contact device (6). - Two point light sources (4), one of which is configured and designed to illuminate the front (11) of the crystalline solar cell (1), and the other of which is configured and designed to illuminate the back (12) of the crystalline solar cell (1). The irradiation occurs from both sides of the crystalline solar cell, but not at the same point. A section of the crystalline solar cell shaded on one side is treated by irradiation from the other side. The contact devices (6) all have: • An optically transparent conductive material, wherein multiple conductive lines are integrated on the surface of the optically transparent conductive material.

8. The apparatus according to claim 7, characterized in that, The multiple conductive wires are made of metal and / or metal alloys.

9. The apparatus according to claim 8, characterized in that, The front contact (14) and the back contact (15) each have fingers that are parallel to each other. The width of the fingers is parallel to the surface of the solar cell and perpendicular to the extension direction of the fingers. The width of each of the multiple conductive lines is smaller than the width of the fingers.

10. A method for improving the ohmic contact between the front contact (14) and the doped layer of a crystalline solar cell (1) using the apparatus according to any one of claims 1 to 6, 7 to 9, comprising the following steps: a) The front contact (14) is in electrical contact with one of the contact devices (6), and the back contact (15) is in electrical contact with the other contact device (6). b) A voltage source (7) applies a voltage opposite to that of the crystalline solar cell (1) to the front contact (14) and the back contact (15), and the applied voltage is lower than the breakdown voltage of the crystalline solar cell (1). c) During the application of voltage, one of the point light sources (4) is directed to a section facing the sun (11) and the other point light source (4) is directed to a section facing away from the sun (12), the distance between the front section and the back section being less than 5 mm, so as to generate current in the respective sections and act on the respective sections.

11. The method according to claim 10, characterized in that, Steps a) through c) are executed statically.

12. The method according to claim 10, characterized in that, The device for improving the ohmic contact between the front contact (14) and the doped layer of the crystalline solar cell (1) is set as a component of the inline production facility of the crystalline solar cell (1), and step a) includes loading the crystalline solar cell (1) into the contact device (6). Between step a) and step c), the contact device (6) acts as a transport unit for the crystalline solar cell (1), transporting the solar cell (1) from the loading / contact area (Z1) of the device for improving the ohmic contact between the front contact (14) and the doped layer of the crystalline solar cell (1) to the irradiation area (Z2), and then to the unloading area (Z3), in which the contact device (6) is spatially separated from the crystalline solar cell (1).

13. The method according to claim 12, characterized in that, The contact device (6) of the improved crystalline solar cell (1) of an inline production facility, which is a device for ohmic contact between the front contact (14) and the doped layer, together with the contacted crystalline solar cell (1), moves in an inline transport cycle from the loading / contact area (Z1), through the irradiation area (Z2), to the unloading area (Z3), and back to the loading / contact area (Z1) via the return loop (Z4).

Images