A method for improving the ohmic contact characteristics of a contact grid of a silicon solar cell, and an apparatus for carrying out the same.
By employing a delayed second contact arrangement with a voltage opposite to the forward direction, the method ensures full illumination of the solar active surface, improving the ohmic contact characteristics of the silicon solar cell's contact grid.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- CE CELL ENG GMBH
- Filing Date
- 2024-07-25
- Publication Date
- 2026-07-29
AI Technical Summary
The ohmic contact characteristics of a silicon solar cell's contact grid are hindered by the partial obscuration of the solar active surface due to contact devices, preventing complete illumination with a point light source.
A method involving a second contact arrangement positioned with a time delay after the first contact arrangement, allowing full illumination of the solar active surface by applying a voltage opposite to the forward direction through both contact arrangements, thereby improving ohmic contact characteristics.
Enables complete illumination of the solar active surface, enhancing the ohmic contact characteristics of the contact grid across the entire surface of the silicon solar cell.
Smart Images
Figure 2026525372000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for improving the ohmic contact characteristics of a contact grid of a silicon solar cell. In this method, first, a silicon solar cell equipped with a contact grid is prepared. The contact grid is contacted using a first contact device electrically connected to one pole of a voltage source. The voltage source is used to apply a voltage in the direction opposite to the forward direction of the silicon solar cell, and the absolute value of this voltage is smaller than the breakdown voltage of the silicon solar cell. When the voltage is applied, a point light source is guided over the solar active surface of the silicon solar cell. Furthermore, the present invention also relates to a device for implementing the same method.
Background Art
[0002] As prior art, DE102018001057.1 discloses a method for improving the ohmic contact characteristics of a contact grid of a silicon solar cell. In this case, the front and back surfaces of the silicon solar cell are electrically biased in the direction opposite to their forward direction. The electrically biased silicon solar cell is then scanned (at least partially) across its solar active surface by a point light source. Thereby, a current density of 200 A / cm 2 to 20,000 A / cm 2 is obtained, and a current acting on the partial region is induced between 10 ns and 10 ms. This method compensates for inappropriate process control in the firing of the metal paste and ensures that the solar cell still achieves the optimal series resistance for its design. For the purpose of applying a voltage in the direction opposite to the forward direction, the front surface of the silicon solar cell is electrically connected to one pole of the voltage source via a first contact device, and the back surface of the silicon solar cell is electrically connected to the other pole of the voltage source via a second contact device.
Summary of the Invention
Problems to be Solved by the Invention
[0003] This type of contact device typically has contact pins or contact bars mounted on the front or back surface of a silicon solar cell for this purpose. A silicon solar cell has a contact grid with contact fingers (Kontaktfinger) on the front surface, which are connected by busbars. If the silicon solar cell has a single-sided design, the back surface is usually metallized over its entire surface. If the silicon solar cell has a double-sided design, the back surface also has contact fingers connected by busbars. The contact pins or contact bars should preferably be mounted on the busbars. Because the busbars are not typically located at the edges of the silicon solar cell, the solar active surface of the silicon solar cell is partially obscured by the respective contact device, thereby preventing access to individual areas when scanning the silicon solar cell with a point light source. This prevents overall improvement of the ohmic contact characteristics of the contact grid on the silicon solar cell.
[0004] The object of the present invention is to further develop a method for improving the ohmic contact characteristics of the contact grid of a silicon solar cell so that complete illumination of the silicon solar cell is possible when scanning with a point light source. [Means for solving the problem]
[0005] This problem is solved using a method having the features of claims 1 and 6. Advantageous embodiments of the method can be found in dependent claims 2 to 5 and 7 to 9. Furthermore, this problem is solved using an apparatus having the features of claim 10. Advantageous embodiments of the apparatus can be found in dependent claims 11 to 13. [Effects of the Invention]
[0006] According to the present invention, the second contact arrangement (zweite Kontaktanordnung) is positioned after the first contact arrangement (erste Kontaktanordnung) with a time delay. From a timing standpoint, the first contact arrangement is already positioned on the contact grid before the second contact arrangement is positioned. This makes it possible to illuminate the second region, which will later be contacted by the second contact arrangement, while a voltage opposite to the forward direction of the silicon solar cell, which is a voltage that generates current, is applied through the first contact arrangement. After the second contact arrangement is positioned on the contact grid and the first contact arrangement is removed, it becomes possible to illuminate the first region that was shielded by the first contact arrangement. Subsequently, the voltage opposite to the forward direction of the silicon solar cell, which is a voltage that generates current, is supplied through the second contact arrangement. As a result, it becomes possible to fully illuminate the solar active surface of the silicon solar cell, thereby improving the ohmic contact characteristics of the contact grid on the silicon solar cell across the entire surface.
[0007] Embodiments of the present invention will be described below with reference to the drawings. The drawings show the following: [Brief explanation of the drawing]
[0008] [Figure 1a] A top view of one embodiment of the apparatus according to the present invention for improving the ohmic contact characteristics of a contact grid on the front surface of a silicon solar cell, with the first contact arrangement of the first contact device in place. [Figure 1b] Side view of the apparatus shown in Figure 1a [Figure 1c] A further top view of the device according to Figure 1a, with both the first contact arrangement of the first contact device and the second contact arrangement of the first contact device in place. [Figure 1d]A further top view of the device according to Figure 1a, with the first contact arrangement of the first contact device removed and the second contact arrangement of the first contact device in place. [Figure 2a] This is a side view of a further embodiment of the apparatus according to the present invention for improving the ohmic contact characteristics of a first contact grid on the front surface of a bifacial silicon solar cell and / or a second contact grid on the back surface of a bifacial silicon solar cell, showing both the first contact arrangement of the first contact device and the first contact arrangement of the second contact device in place. [Figure 2b] A side view of the device according to Figure 2a, showing the state in which all of the first contact arrangements of the first contact device, the second contact arrangement of the first contact device, the first contact arrangement of the second contact device, and the second contact arrangement of the second contact device are arranged. [Figure 2c] A side view of the apparatus according to Figure 2a, with the second contact arrangement in place and the first contact arrangement removed. [Figure 3a] Side view of a further embodiment of the apparatus according to the present invention for improving the ohmic contact characteristics of a first contact grid on the front surface of a silicon solar cell. [Figure 3b] Side view of a further embodiment of the apparatus according to the present invention for improving the ohmic contact characteristics of a first contact grid on the front surface of a silicon solar cell. [Figure 4a] Side view of a further embodiment of the apparatus according to the present invention for improving the ohmic contact characteristics of a first contact grid on the front surface of a silicon solar cell. [Figure 4b] Side view of a further embodiment of the apparatus according to the present invention for improving the ohmic contact characteristics of a first contact grid on the front surface of a silicon solar cell. [Modes for carrying out the invention]
[0009] Figure 1a shows a top view of apparatus 1 according to the present invention for improving the ohmic contact characteristics of a contact grid on the front surface 2a (Figure 1b) of a single-sided silicon solar cell 2. Apparatus 1 comprises a first contact device 4, a second contact device 5, a voltage source, and a point light source (Figure 1b) 3. The first contact device 4 is electrically connected to one pole of the voltage source, and the second contact device 5 is electrically connected to the other pole of the voltage source. The voltage source is not shown in the figure. The voltage source is configured to apply a voltage via the two contact devices that is in the opposite direction to the forward direction of the silicon solar cell 2 and has an absolute value smaller than the breakdown voltage of the silicon solar cell. Furthermore, the point light source 3 is configured to be guided onto the solar active surface on the front surface 2a of the silicon solar cell 2 when a voltage in the opposite direction to the forward direction of the silicon solar cell 2 is applied. Advantageously, the point light source 3 is a laser and can be guided onto the solar active surface on the front surface 2a of the silicon solar cell 2, for example, using a movable mirror. However, the present invention is not limited thereto. Similarly, the point light source 3 is not limited to a laser. For example, the point light source 3 may be a focused white light source.
[0010] In Figure 1a, the front surface 2a of the silicon solar cell 2 is visible, but the contact grid on the front surface 2a is not shown. The back surface 2b of the silicon solar cell 2 is not visible in the figure. The back surface 2b of a single-sided silicon solar cell 2 is usually metallized over its entire surface and forms the back surface electrical contacts of the silicon solar cell. In the shown embodiment, the second contact device 5 takes the form of two contact bars that abut against the back surface 2b of the silicon solar cell 2. For this purpose, the contact bars can be moved to the back surface 2b of the silicon solar cell 2, or the silicon solar cell 2 can be moved so that its back surface 2b is in contact with the contact bars. Advantageously, the attractive force between the contact bars and the back surface 2b of the silicon solar cell 2 ensures that the contact bars are securely held against the back surface 2b of the silicon solar cell 2.
[0011] The first contact device 4 is configured to contact the contact grid on the front surface 2a of the silicon solar cell 2. For this purpose, the first contact device 4 has a first contact arrangement 4a and a second contact arrangement 4b.
[0012] After the silicon solar cell 2 is positioned on the apparatus 1, the first contact arrangement 4a is placed on a portion of the contact grid (Kontaktgitterabschnitt) in the first region 6a on the front surface 2a. Similarly, the second contact apparatus 5 is placed on the back surface 2b of the silicon solar cell 2 before, during, or after the placement of the first contact arrangement. Once the back surface 2b is in contact, and a portion of the contact grid in the first region 6a on the front surface 2a is also in contact, a voltage in the opposite direction to the forward direction of the silicon solar cell 2 is then supplied by the voltage source, and thereafter, the point light source 3 is guided onto the second region 6b on the front surface 2a, which is located outside the first region 6a. In the figure, the path 7 of the light beam 8 (Figure 1b) emitted by the point light source 3 (Figure 1b) on the front surface 2a is shown by a dashed line. This is one possible path 7 for the point light source 3 in the second region of the front surface 2a, but the present invention is not limited thereto. In principle, other paths 7 for the point light source 3 in the second region of the silicon solar cell 2 are also possible. When the light beam emitted by the point light source 3 is guided over the second region of the front surface 2a of the silicon solar cell 2, a current is induced in the silicon solar cell 2, particularly in the irradiated region, improving the ohmic contact characteristics of the contact grid on the front surface 2a of the single-sided silicon solar cell 2 (especially in the irradiated region). The current typically generated during this process is 1000 A / cm² relative to the irradiated region. 2 From 200,000 A / cm² 2 It has a current density in the range of [this range].
[0013] Figure 1b shows a side view of the apparatus 1 according to Figure 1a. Furthermore, this figure also shows a point light source 3 configured as a laser. The light beam 8 emitted by the point light source 3 is shown by a dashed line, and the position of the light beam 8 represents a snapshot.
[0014] The first contact arrangement 4a of the first contact device 4 and the second contact arrangement 4b of the first contact device 4 are configured as lever arms having electrically conductive contact pads, and by tilting the respective lever arms, they can be placed on corresponding parts of the contact grid on the front surface 2a of the silicon solar cell 2. In the method step shown, the first contact arrangement 4a is arranged on a part of the contact grid in the first region 6a on the front surface 2a of the silicon solar cell 2. The second contact arrangement 4b is removed from a part of the contact grid in the second region 6b on the front surface 2a of the silicon solar cell 2. As a result, in this state, the second region 6b of the front surface 2a is not shaded by the second contact arrangement 4b and can be irradiated by the point light source 3.
[0015] The two contact bars of the second contact device 5 are integrated into the suction table. For the purpose of contacting the back surface 2b, the suction table having the contact bars is moved to the back surface 2b of the silicon solar cell 2, or the silicon solar cell 2 is moved such that its back surface 2b contacts the suction table.
[0016] In the figure according to Figure 1b, the voltage source of the device 1 is not shown.
[0017] Figure 1c shows a further top view of the device 1 according to Figure 1a after the second region 6b on the front surface 2a of the silicon solar cell has been irradiated. In addition to the first contact arrangement 4a of the first contact device 4, the second contact arrangement 4b of the first contact device 4 is also in contact with a part of the contact grid on the front surface 2a of the silicon solar cell 2. For this purpose, the second contact arrangement 4b is arranged on a part of the contact grid in the second region 6b on the front surface 2a. After the second contact arrangement 4b is arranged, the point light source 3 is guided onto a third region 6c on the front surface 2a that is located outside the first region 6a and the second region 6b. Again, in the silicon solar cell 2, a current is induced, especially in the irradiated region of the silicon solar cell 2, and the ohmic contact characteristics of the contact grid on the front surface 2a of the single-sided silicon solar cell 2 are improved (especially in the irradiated region).
[0018] Figure 1d shows a further top view of the device 1 according to Figure 1a after the third region 6c on the front surface 2a of the silicon solar cell has been irradiated. The first contact arrangement is removed from a part of the contact grid in the first region 6a on the front surface 2a. The second contact arrangement 4b of the first contact device 4 remains arranged on a part of the contact grid in the second region 6b on the front surface 2a. With the contact grid thus contacted, the point light source 3 is guided onto the first region 6a on the front surface 2a.
[0019] To arrange the first contact arrangement 4a of the first contact device 4 on the contact grid on the front surface 2, the lever arm of the first contact arrangement 4a is rotated downward. To remove the first contact arrangement 4a of the first contact device 4 from the contact grid on the front surface 2, the lever arm of the first contact arrangement 4a is rotated upward. To arrange the second contact arrangement 4b of the first contact device 4 on the contact grid on the front surface 2, the lever arm of the second contact arrangement 4a is rotated downward. To remove the second contact arrangement 4b of the first contact device 4 from the contact grid on the front surface 2, the lever arm of the second contact arrangement 4b is rotated upward.
[0020] The apparatus 1 and method described above can also be applied to a bifacial silicon solar cell 2. Instead of having planar back contacts, the bifacial silicon solar cell similarly has back contacts in the form of a contact grid, i.e., it has a first contact grid on the front surface 2a and a second contact grid on the back surface 2b. In the case of the bifacial silicon solar cell 2, this results in the presence of solar active surfaces on both the front surface 2a and the back surface 2b. The bifacial silicon solar cell 2 can be inserted into the apparatus 1 described above such that the first contact grid on the front surface 2a is contacted by the first contact device 4 and the second contact grid on the back surface 2b is contacted by the second contact device 5, or the first contact grid on the front surface 2a is contacted by the second contact device 5 and the second contact grid on the back surface 2b is contacted by the first contact device 4. Correspondingly, in the first case, the point light source 3 illuminates the front surface 2a of the bifacial silicon solar cell 2, and in the second case, it illuminates the back surface 2b. By processing the double-sided silicon solar cell 2 using the apparatus 1 and method described above, the ohmic contact characteristics of the contact grid on both the front surface 2a and the back surface 2b are simultaneously improved.
[0021] Figure 2a shows a side view of a further embodiment of the apparatus 1 according to the present invention for improving the ohmic contact characteristics of a first contact grid on the front surface 2a of a bifacial silicon solar cell 2 and / or a second contact grid on the back surface 2b of a bifacial silicon solar cell.
[0022] In contrast to the apparatus 1 shown in Figure 1a, in the embodiment of apparatus 1 according to the present invention shown in Figure 2a, the second contact device 5 no longer has a fixed contact bar, and instead again has a first contact arrangement 5a and a second contact arrangement 5b that are movable during irradiation. This apparatus 1 is particularly suitable for bifacial silicon solar cells, but can also be used for single-sided silicon solar cells 2.
[0023] As shown in Figure 2a, when the first contact arrangement 4a of the first contact device 4 is positioned on a portion of the first contact grid in the first region 6a on the front surface 2a, the first contact arrangement 5a of the second contact device 5 is also positioned on a portion of the second contact grid in the first region 6a on the back surface 2b, and thereafter the second region 6b on the front surface 2a of the double-sided silicon solar cell 2 is illuminated by the point light source 3.
[0024] As shown in Figure 2b, when the second contact arrangement 4b of the first contact device 4 is positioned on a portion of the first contact grid in the second region 6b on the front surface 2a, the second contact arrangement 5b of the second contact device 5 is also positioned on a portion of the second contact grid in the second region 6b on the back surface 2b, and thereafter the third region 6c on the front surface 2a of the double-sided silicon solar cell 2 is illuminated by the point light source 3.
[0025] As shown in Figure 2c, when the first contact arrangement 4a of the first contact device 4 is removed from a portion of the contact grid in the first region 6a on the front surface 2a, the first contact arrangement 5a of the second contact device is also removed from a portion of the contact grid in the first region 6a on the back surface 2b, and thereafter the first region 6a on the front surface 2a of the double-sided silicon solar cell 2 is illuminated by the point light source 3. However, if only the front surface 2a of the double-sided silicon solar cell 2 is illuminated, it is not necessary for the first contact arrangement 5a of the second contact device to be removed from a portion of the contact grid in the first region 6a on the back surface 2b.
[0026] In the embodiment shown in Figures 2a to 2c, the back surface 2b of the double-sided silicon solar cell 2 can also be irradiated by the point light source 3 as an alternative to irradiating the front surface 2a. Furthermore, it is possible to irradiate both the front surface 2a and the back surface 2b of the double-sided silicon solar cell 2 simultaneously. This can be achieved by using an additional point light source 3, or by using an existing point light source 3 to split the synchrotron radiation with a beam splitter and guiding it to the front surface 2a and back surface 2b with a mirror system. In this case, it is advantageous that both the first contact arrangement 4a and the second contact arrangement 4b of the first contact device 4, and the first contact arrangement 5a and the second contact arrangement 5b of the second contact device 5, can be positioned and removed relative to the first contact grid on the front surface 2a and the second contact grid on the back surface 2b of the silicon solar cell 2 during the irradiation of regions 6a and 6b.
[0027] The first contact arrangement 5a and the second contact arrangement 5b of the second contact device 5 are configured as lever arms having electrically conductive contact pads, and by tilting each lever arm, they can be placed on corresponding portions of the contact grid on the back surface 2b of the silicon solar cell 2. To position the first contact arrangement 5a on the contact grid on the back surface 2, the lever arm of the first contact arrangement 5a is rotated downward. To remove the first contact arrangement 5a from the contact grid on the back surface 2, the lever arm of the first contact arrangement 5a is rotated upward. To position the second contact arrangement 5b on the contact grid on the back surface 2, the lever arm of the second contact arrangement 5b is rotated downward. To remove the second contact arrangement 5b from the contact grid on the front surface 2, the lever arm of the second contact arrangement 5b is rotated upward.
[0028] In the case of a contact grid in which contact fingers are connected to each other via busbars, the contact arrangement should preferably be positioned on these busbars, but the present invention is not limited thereto.
[0029] In the embodiments shown in Figures 3a and 3b, the apparatus 1 for improving the ohmic contact characteristics of the contact grid on the front surface 2a of a silicon solar cell comprises a first contact device 4, a second contact device 5, a voltage source, and a point light source 3. The first contact device 4 is electrically connected to one pole of the voltage source, and the second contact device 5 is electrically connected to the other pole of the voltage source. The first contact device 4 is configured to contact the contact grid, and the second contact device 5 is configured to contact the back surface contacts of the silicon solar cell 2. The voltage source is configured to apply a voltage in the opposite direction to the forward direction of the silicon solar cell 2, and a voltage whose absolute value is less than the breakdown voltage of the silicon solar cell. The point light source 3 is configured to be guided across the solar active surface on the front surface 2a of the silicon solar cell 2 when a voltage in the opposite direction to the forward direction of the silicon solar cell 2 is applied. The first contact device 4 has a first contact arrangement 4a and a second contact arrangement 4b. The first contact arrangement 4a is configured to be positioned on and detachable from a portion of the contact grid in a first region 6a on the front surface 2a. The second contact arrangement 4b is configured to be positioned on and detachable from a portion of the contact grid in the second region 6b on the front surface 2a, which is located outside the first region 6a. The point light source 3 is configured to be guided over the second region 6b on the front surface 2a while the first contact arrangement 4a is positioned on a portion of the contact grid in the first region 6a on the front surface 2a, and the second contact arrangement 4b is not positioned on a portion of the contact grid in the second region 6b on the front surface 2a. Furthermore, the point light source 3 is configured to be guided over the first region 6a on the front surface 2a while the first contact arrangement 4a is not positioned on a portion of the contact grid in the first region 6a on the front surface 2a, and the second contact arrangement 4b is positioned on a portion of the contact grid in the second region 6b on the front surface 2a.
[0030] In the shown embodiment, the second contact device 5 is formed by two contact strips that abut against the back surface 2b of the silicon solar cell 2. For this purpose, the contact bar can be moved to the back surface 2b of the silicon solar cell 2, or the back surface 2b of the silicon solar cell 2 can be moved to the contact bar. Advantageously, the attraction between the contact bar and the back surface 2b of the silicon solar cell 2 helps to keep the contact bar in secure contact with the back surface 2b of the silicon solar cell 2. The first contact arrangement 4a and the second contact arrangement 4b of the first contact device 4 are configured according to the embodiment shown in Figure 1b.
[0031] For the purpose of bringing the first contact device 4 into contact with the contact grid, first the first contact arrangement 4a of the first contact device 4 is placed on a portion of the contact grid in the first region 6a on the front surface 2a, and after applying a voltage in the opposite direction to the forward direction of the silicon solar cell 2, the point light source 3 is first guided onto the second region 6b on the front surface 2a, which is located outside the first region 6a. Next, the second contact arrangement 4b of the first contact device 4 is placed on a portion of the contact grid in the second region 6b on the front surface 2a, and the point light source 3 is guided onto the first region on the front surface 2a while the first contact arrangement 4a of the first contact device 4 is not on a portion of the contact grid in the first region 6a on the front surface 2a.
[0032] In contrast to the embodiments shown in Figures 3a and 3b, the embodiments shown in Figures 4a and 4b have a modified second contact device 5. The second contact device 5 has a first contact arrangement 5a and a second contact arrangement 5b. The first contact arrangement 5a of the second contact device 5 is configured to be positioned on a portion of the contact grid in the first region 6a on the back surface 2b after the first contact arrangement 4a of the first contact device 4 is positioned on a portion of the contact grid in the first region 6a on the front surface 2a. The first contact arrangement 5a of the second contact device 5 is configured to be positioned on a portion of the contact grid in the first region 6a on the back surface 2b after the first contact arrangement 4a of the first contact device 4 is removed from a portion of the contact grid in the first region 6a on the front surface 2a. The second contact arrangement 5b of the second contact device 5 is configured to be positioned on a portion of the contact grid in the second region 6b on the back surface 2b after the second contact arrangement 4b of the first contact device 4 is positioned on a portion of the contact grid in the second region 6b on the front surface 2a. The second contact arrangement 5b of the second contact device 5 is configured to be removed from a portion of the contact grid in the second region 6b on the back surface 2b after the second contact arrangement 4b of the first contact device 4 has been removed from a portion of the contact grid in the second region 6b on the front surface 2a.
[0033] In addition to the methods described in Figures 3a and 3b, the methods shown in Figures 4a and 4b also include the following steps: When the first contact arrangement 4a of the first contact device 4 is positioned on a portion of the first contact grid in the first region 6a on the front surface 2a, the first contact arrangement 5a of the second contact device 5 is positioned on a portion of the second contact grid in the first region 6a on the back surface 2b. When the second contact arrangement 4b of the first contact device 4 is positioned on a portion of the first contact grid in the second region 6b on the front surface 2a, the second contact arrangement 5b of the second contact device 5 is positioned on a portion of the second contact grid in the second region 6b on the back surface 2b. When the first contact arrangement 4a of the first contact device 4 is removed from a portion of the contact grid in the first region 6a on the front surface 2a, the first contact arrangement 5a of the second contact device 5 is also removed from a portion of the contact grid in the first region 6a on the back surface 2b. The first contact arrangement 4a of the first contact device 4, the second contact arrangement 4b of the first contact device 4, the first contact arrangement 5a of the second contact device 5, and the second contact arrangement 5b of the second contact device 5 are configured in accordance with the embodiment shown in Figure 2a.
[0034] In the embodiments described above, the first contact arrangement 4a of the first contact device 4 and / or the second contact arrangement 4b of the first contact device 4 and / or the first contact arrangement 5a of the second contact device 5 and / or the second contact arrangement 5b of the second contact device 5 are preferably movable relative to the silicon solar cell 2 by electric motor or pneumatic drive, thereby enabling automation of the entire process. [Explanation of Symbols]
[0035] 1 device 2. Silicon solar cells 2a front 2b Back side 3 point light source 4 First contact device 4a First contact arrangement of the first contact device 4 4b Second contact arrangement of the first contact device 4 5 Second contact device 5a First contact arrangement of the second contact device 5 5b Second contact arrangement of the second contact device 5 6a 1st area 6b 2nd area 6c 3rd area 7. Path of point light source 3 on silicon solar cell 1 8-point light source 3 light beam
Claims
1. A method for improving the ohmic contact characteristics of a first contact grid on the front surface (2a) of a single-sided or double-sided silicon solar cell, First, a silicon solar cell (2) is prepared, which has the first contact grid on the front surface (2a) of the silicon solar cell (1) and back surface contacts on the back surface (2b) of the silicon solar cell (1). The first contact grid is made contact using a first contact device (4) electrically connected to one pole of the voltage source, and the back contact is made contact using a second contact device (5) electrically connected to the other pole of the voltage source. The voltage source is used to apply a voltage in the opposite direction to the forward direction of the silicon solar cell (2) and whose absolute value is smaller than the breakdown voltage of the silicon solar cell. A method by which a point light source (3) is guided onto the solar active surface on the front surface (2a) of the silicon solar cell (2) when the voltage is applied, For the purpose of bringing the first contact grid into contact with the first contact device (4), first, the first contact arrangement (4a) of the first contact device (4) is positioned in a part of the first contact grid in the first region (6a) of the front surface (2a), After applying a voltage in the opposite direction to the forward direction of the silicon solar cell (2), the point light source (3) is first guided onto the second region (6b) of the front surface (2a) located outside the first region (6a), Next, the second contact arrangement (4b) of the first contact device (4) is positioned in a part of the first contact grid in the second region (6b) of the front surface (2a), The method is characterized in that the point light source (3) is guided onto the first region (6a) of the front surface (2a) after the first contact arrangement (4a) of the first contact device (4) has been removed from the portion of the first region (6a) of the front surface (2a).
2. The method according to claim 1, characterized in that after the point light source (3) is guided onto the first region of the front surface (2a), and before the first contact arrangement (4a) of the first contact device (4) is removed from a portion of the contact grid in the first region (6a) of the front surface (2a), the point light source (3) is guided onto a third region (6c) of the front surface (2a) that is located outside the first region (6a) and the second region (6b).
3. The method according to claim 1 or claim 2, characterized in that, in the case of a double-sided solar cell, the back surface contact on the back surface (2b) of the silicon solar cell (1) consists of a second contact grid.
4. When the first contact arrangement (4a) of the first contact device (4) is positioned on a portion of the first contact grid in the first region (6a) of the front surface (2a), the first contact arrangement (5a) of the second contact device (5) is positioned on a portion of the second contact grid in the first region (6a) of the back surface (2b), The method according to claim 3, characterized in that when the second contact arrangement (4b) of the first contact device (4) is positioned on a portion of the first contact grid in the second region (6b) of the front surface (2a), the second contact arrangement (5b) of the second contact device (5) is positioned on a portion of the second contact grid in the second region (6b) of the back surface (2b).
5. The method according to claim 4, characterized in that when the first contact arrangement (4a) of the first contact device (4) is removed from a portion of the first contact grid in the first region (6a) of the front surface (2a), the first contact arrangement (5a) of the second contact device is also removed from a portion of the second contact grid in the first region (6a) of the back surface (2b).
6. A method for improving the ohmic contact characteristics of a first contact grid on the front surface (2a) of a double-sided silicon solar cell (2) and / or a second contact grid on the back surface (2b) of a double-sided silicon solar cell, First, the silicon solar cell (2) having two contact grids is prepared. The first contact grid is made contact using a first contact device (4) electrically connected to one pole of the voltage source, and the second contact grid is made contact using a second contact device (5) electrically connected to the other pole of the voltage source. The voltage source is used to apply a voltage in the opposite direction to the forward direction of the silicon solar cell (2) and whose absolute value is smaller than the breakdown voltage of the silicon solar cell. For the purpose of bringing the second contact grid into contact with the second contact device (5), first, the first contact arrangement (5a) of the second contact device (5) is positioned in a part of the second contact grid in the first region (6a) of the back surface (2b), After applying a voltage in the opposite direction to the forward direction of the silicon solar cell (2), the point light source (3) is first guided onto the second region (6b) of the back surface (2b) located outside the first region (6a), Next, the second contact arrangement (5b) of the second contact device (5) is positioned in a part of the second contact grid in the second region (6b) of the back surface (2b), Next, the method is characterized in that the point light source (3) is guided onto the first region of the back surface (2b) of the silicon solar cell (2) while the first contact arrangement (5a) of the second contact device (5) is not positioned on the part of the first region (6a) of the back surface (2b).
7. The method according to claim 6, characterized in that after the point light source (3) has been guided onto the first region of the back surface (2b), and before the first contact arrangement (5a) of the second contact device (5) is removed from a portion of the second contact grid in the first region (6a) of the back surface (2b), the point light source (3) is guided onto a third region (6c) of the back surface (2b) located outside the first region (6a) and the second region (6b).
8. When the first contact arrangement (5a) of the second contact device (5) is positioned on a portion of the second contact grid in the first region (6a) of the back surface (2b), the first contact arrangement (4a) of the first contact device (4) is positioned on a portion of the first contact grid in the first region (6a) of the front surface (2a), The method according to claim 7, characterized in that when the second contact arrangement (5b) of the second contact device (5) is positioned on a portion of the second contact grid in the second region (6b) of the back surface (2b), the second contact arrangement (4b) of the first contact device (4) is positioned on a portion of the first contact grid in the second region (6b) of the front surface (2a).
9. The method according to claim 8, characterized in that when the first contact arrangement (5a) of the second contact device (5) is removed from a portion of the second contact grid in the first region (6a) of the back surface (2b), the first contact arrangement (4a) of the first contact device is also removed from a portion of the first contact grid in the first region (6a) of the front surface (2a).
10. An apparatus (1) for improving the ohmic contact characteristics of a contact grid on the front surface (2a) of a silicon solar cell (2), The system comprises a first contact device (4), a second contact device (5), a voltage source, and a point light source (3), The first contact device (4) is electrically connected to one pole of the voltage source, and the second contact device (5) is electrically connected to the other pole of the voltage source. The first contact device (4) is configured to contact the contact grid, and the second contact device (5) is configured to contact the back surface contacts of the silicon solar cell (2). The voltage source is configured to apply a voltage in the opposite direction to the forward direction of the silicon solar cell (2) and whose absolute value is smaller than the breakdown voltage of the silicon solar cell. In a device in which the point light source (3) is guided onto the solar active surface on the front surface (2a) of the silicon solar cell (2) when the voltage is applied in the opposite direction to the forward direction of the silicon solar cell, The first contact device (4) has a first contact arrangement (4a) and a second contact arrangement (4b), The first contact arrangement (4a) is positioned in a portion of the contact grid in the first region (6a) of the front surface (2a) and is removable. The second contact arrangement (4b) is positioned in a portion of the contact grid in the second region (6b) of the front surface (2a) and is removable. When the first contact arrangement (4a) of the first contact device (4) is positioned on a portion of the contact grid in the first region (6a) of the front surface (2a), and the second contact arrangement (4b) is removed from the portion of the contact grid in the second region (6b) of the front surface (2a), the point light source (3) is guided onto the second region (6b) of the front surface (2a). The apparatus (1) is characterized in that when the first contact arrangement (4a) of the first contact device (4) is removed from a portion of the first region (6a) of the front surface (2a), and the second contact arrangement (4b) of the first contact device (4) is positioned on a portion of the contact grid in the second region (6b) of the front surface (2a), the point light source (3) is guided onto the first region (6a) of the front surface (2a).
11. The apparatus (1) according to claim 10, characterized in that the first contact arrangement (4a) is located on a portion of the contact grid in the first region (6a) of the front surface (2a), and the second contact arrangement (4b) is located on a portion of the contact grid in the second region (6b) of the front surface (2a), while the point light source (3) is configured to be guided onto the third region (6c) of the front surface (2a).
12. The second contact device (5) has a first contact arrangement (5a) and a second contact arrangement (5b), The first contact arrangement (5a) of the second contact device (5) is configured to be positioned on a portion of the first region (6a) of the back surface (2b) when the first contact arrangement (4a) of the first contact device (4) is positioned on a portion of the contact grid in the first region (6a) of the front surface (2a). The first contact arrangement (5a) of the second contact device (5) is configured to be removed from a portion of the first region (6a) on the back surface (2b) when the first contact arrangement (4a) of the first contact device (4) is removed from a portion of the contact grid in the first region (6a) on the front surface (2a). The second contact arrangement (5b) of the second contact device (5) is configured to be positioned on a portion of the second region (6b) of the back surface (2b) when the second contact arrangement (4b) of the first contact device (4) is positioned on a portion of the contact grid in the second region (6b) of the front surface (2a). The apparatus (1) according to claim 10 or claim 11, characterized in that the second contact arrangement (5b) of the second contact device (5) is configured to be removed from a portion of the second region (6b) of the back surface (2b) when the second contact arrangement (4b) of the first contact device (4) is removed from a portion of the contact grid in the second region (6b) of the front surface (2a).
13. The apparatus (1) according to any one of claims 10 to 12, characterized in that the first contact arrangement (4a) of the first contact device (4) and / or the second contact arrangement (4b) of the first contact device (4) and / or the first contact arrangement (5a) of the second contact device (5) and / or the second contact arrangement (5b) of the second contact device (5) are movable relative to the silicon solar cell (2) by an electric motor or pneumatic drive.