Method for improving ohmic contact characteristic of contact gate of silicon solar cell and device for implementing method

Abstract

The invention relates to a method for improving the ohmic contact properties of a contact gate of a silicon solar cell, in which first a silicon solar cell having a contact gate is provided, the contact gate being in contact with a first contact device (4) which is electrically connected to one of the poles of a voltage source, a voltage source is used to apply a voltage which is opposite to the silicon solar cell in forward direction and is less than the breakdown voltage of the silicon solar cell, and the point light source (3) is guided to pass through the solar active area of the silicon solar cell while the voltage is applied. The invention aims to improve the method for improving the ohmic contact characteristic of the contact gate of the silicon solar cell, so that the complete irradiation of the silicon solar cell can be realized when a point light source is used for scanning. This problem is solved in that the silicon solar cells are in alternating electrical contact with the first contact unit (4a) and the second contact unit (4b) of the first and / or second contact means when illuminated with the point light source (3).

Description

Technical Field

[0001] This invention relates to a method for improving the ohmic contact characteristics of a contact grid in a silicon solar cell. The method first provides a silicon solar cell with a contact grid, the contact grid being contacted by a first contact device electrically connected to one pole of a voltage source. A voltage opposite to the positive voltage of the silicon solar cell and less than its breakdown voltage is applied by the voltage source. Simultaneously, a point light source is guided through the solar active region of the silicon solar cell. Furthermore, the invention also relates to an apparatus for performing this method. Background Technology

[0002] In the prior art, DE 10 2018 001 057.1 discloses a method for improving the ohmic contact characteristics of the contact gate in silicon solar cells. In this method, a pre-bias voltage opposite to the forward direction is applied to the front and back sides of the silicon solar cell. Subsequently, the pre-biased silicon solar cell (at least segmented) is scanned over the solar active region using a point light source. This process induces a current flow, wherein the current flow has a current flow of 200 A / cm in the illuminated local area. 2 Up to 20,000 A / cm 2 The current density is measured, and the duration of the current applied to the local area is 10 ns to 10 ms. This method compensates for process defects that occur during the sintering of the metal paste, allowing the solar cell to still achieve the optimal series resistance suitable for its structure. To apply a voltage opposite to its forward direction, the front side of the silicon solar cell is electrically connected to one pole of the voltage source via a first contact device, and the back side of the silicon solar cell is electrically connected to the other pole of the voltage source via a second contact device.

[0003] Typically, such contact devices are equipped with contact pins or contact strips, respectively located on the front or back of the silicon solar cell. The front of the silicon solar cell has a contact grid with contact fingers and a busbar connecting these contact fingers. For single-sided silicon solar cells, the back is usually fully metallized. For bifacial silicon solar cells, the back also has contact fingers and a busbar connecting these contact fingers. Preferably, the contact pins or contact strips are located on the busbar. Since the busbar is usually not arranged at the edge of the silicon solar cell, the contact device partially obstructs the photovoltaic active surface of the silicon solar cell. This results in some areas not being illuminated by the point light source when scanning the silicon solar cell with a point light source. Consequently, the ohmic contact characteristics of the silicon solar cell contact grid cannot be improved across the entire surface. Summary of the Invention

[0004] The present invention aims to improve the method for enhancing the ohmic contact characteristics of the contact grid of silicon solar cells in order to achieve complete illumination of the silicon solar cells when scanning with a point light source.

[0005] This task is accomplished by methods having the features of claims 1 and 6, respectively. Advantageous embodiments of the invention are embodied in dependent claims 2 to 5 and 7 to 9. Furthermore, this task is also accomplished by an apparatus having the features of claim 10. Advantageous embodiments are embodied in dependent claims 11 to 13.

[0006] According to the present invention, each second contact unit is placed on the surface after the corresponding first contact unit in a time-staggered manner. The first contact unit is placed on the contact grid before the second contact unit. This allows for the illumination of the second region subsequently contacted by the second contact unit, while a voltage opposite to the positive direction of the silicon solar cell, required for current flow, is applied through the first contact unit. If the first contact unit is removed while the second contact unit is on the contact grid, illumination of the first region blocked by the first contact unit is achieved. At this time, a voltage opposite to the positive direction of the silicon solar cell, required for current flow, is provided through the second contact unit. This allows for the full-surface illumination of the solar active surface of the silicon solar cell, thereby improving the ohmic contact characteristics of the silicon solar cell contact grid across the entire surface. Attached Figure Description

[0007] The embodiments of the present invention will now be described with reference to the accompanying drawings. The details are as follows:

[0008] Figure 1a This is a top view of one embodiment of the device of the present invention, which is used to improve the ohmic contact characteristics of the front contact grid of a silicon solar cell, showing a first contact unit of a first contact device placed on the surface.

[0009] Figure 1b for Figure 1a Side view of the device shown

[0010] Figure 1c for Figure 1a Another top view of the device shows a first contact unit of the first contact device placed on the surface, and a second contact unit of the first contact device placed on the surface.

[0011] Figure 1d for Figure 1a Another top view of the device shows the first contact unit of the first contact device that has been removed, and the second contact unit of the first contact device that has been placed on the surface.

[0012] Figure 2aThis is a side view of another embodiment of the device of the present invention, which is used to improve the ohmic contact characteristics of the first contact grid on the front side and / or the second contact grid on the back side of a bifacial silicon solar cell. It shows the first contact unit of the first contact device placed on the surface and the first contact unit of the second contact device placed on the surface.

[0013] Figure 2b for Figure 2a The side view of the device shown illustrates a first contact unit placed on a surface, a first contact unit of a first contact device placed on a surface, and a second contact unit of a second contact device placed on a surface.

[0014] Figure 2c for Figure 2a The side view of the device shown illustrates the second contact unit placed on the surface and the first contact unit that has been removed.

[0015] Figure 3a , Figure 3b This is a side view of another embodiment of an apparatus of the present invention for improving the ohmic contact characteristics of the first contact grid on the front side of a silicon solar cell.

[0016] Figure 4a , Figure 4b This is a side view of another embodiment of an apparatus for improving the ohmic contact characteristics of the first contact grid on the front side of a silicon solar cell according to the present invention. Detailed Implementation

[0017] Figure 1a This is a top view of the device 1 for improving the ohmic contact characteristics of the contact grid on the front side 2a of a single-sided silicon solar cell according to the present invention. The device 1 includes 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 voltage source is not shown in the figure. The voltage source is designed to apply a voltage opposite to the forward direction of the silicon solar cell 2 and less than the breakdown voltage of the silicon solar cell between the two contact devices. Furthermore, the point light source 3 is designed to be guided through the solar active region of the front side 2a of the silicon solar cell 2 when a voltage opposite to the forward direction of the silicon solar cell 2 is applied. Preferably, the point light source 3 is a laser, for example, guided through the solar active region of the front side 2a of the silicon solar cell 2 by a movable reflector. Of course, the present invention is not limited to this. The point light source 3 is also not limited to a laser; for example, the point light source 3 can also be a focused white light source.

[0018] exist Figure 1aThe front side 2a of the silicon solar cell 2 is shown in the diagram, but the contact grid on the front side 2a is not shown. The back side 2b of the silicon solar cell 2 is not visible in the diagram. The back side 2b of a single-sided silicon solar cell 2 is typically metallized on its entire surface, forming the back contact of the silicon solar cell. In the illustrated embodiment, the second contact device 5 consists of two contact strips that are attached to the back side 2b of the silicon solar cell 2. For this purpose, the contact strips can be guided onto the back side 2b of the silicon solar cell 2, or the back side 2b of the silicon solar cell 2 can be guided onto the contact strips. Preferably, a strong adhesion between the contact strips and the back side 2b is ensured by the adsorption effect formed between the contact strips and the back side 2b of the silicon solar cell 2.

[0019] The first contact device 4 is designed to contact the contact grid on the front side 2a of the silicon solar cell 2. For this purpose, the first contact device 4 includes a first contact unit 4a and a second contact unit 4b.

[0020] After the silicon solar cell 2 is provided to the device 1, the first contact unit 4a is placed on a portion of the contact grid within the first region 6a of the front side 2a. Similarly, before, during, or after the first contact unit is placed on the surface, the second contact device 5 is placed on the back side 2b of the silicon solar cell 2. After contacting the back side 2b and the portion of the contact grid within the first region 6a of the front side 2a, a voltage opposite to the positive direction of the silicon solar cell 2 is applied by a power source, subsequently guiding the point light source 3 through a second region outside the first region 6a of the front side 2a. In the illustration, the beam 8 emitted by the point light source 3 ( Figure 1b The path 7 on the front side 2a is indicated by a dashed line. This is one possible path 7 of the point light source 3 on the second region of the front side 2a, but the invention is not limited thereto. In principle, the point light source 3 can also have other paths 7 on the second region of the front side of the silicon solar cell 2. When the light beam emitted by the point light source 3 is guided through the second region of the front side of the silicon solar cell 2, a current flow is excited within the silicon solar cell 2, especially in the irradiated area, thereby improving the ohmic contact characteristics of the contact grid on the front side 2a of the single-sided silicon solar cell 2 (especially in the irradiated area). Typically, this process generates a current intensity in the range of 1,000 A / cm on the irradiated surface. 2 Up to 200,000 A / cm 2 The current.

[0021] Figure 1b for Figure 1a The figure shows a side view of device 1. Additionally, a point light source 3, designed as a laser, is also shown in the figure. The beam 8 emitted by the point light source 3 is indicated by a dashed line, and the position of the beam 8 is a snapshot.

[0022] The first contact unit 4a and the second contact unit 4b of the first contact device 4 are designed as lever arms with conductive contact pads. These lever arms can be tilted and placed on corresponding portions of the contact grid on the front side 2a of the silicon solar cell 2. In the illustrated process state, the first contact unit 4a is placed on a portion of the contact grid within the first region 6a of the front side 2a of the silicon solar cell 2. The second contact unit 4b is then lifted away from the contact grid portion within the second region 6b of the front side 2a of the silicon solar cell 2. Therefore, in this state, the second contact unit 4b does not obstruct the second region 6b of the front side 2a, allowing this region to be illuminated by the point light source 3.

[0023] The two contact strips of the second contact device 5 are integrated into an adsorption platform. In order to make contact with the back surface 2b, the adsorption platform together with the contact strips is guided to the back surface 2b of the silicon solar cell 2, or the silicon solar cell 2 and its back surface 2b are guided to the adsorption platform.

[0024] exist Figure 1b The voltage source of device 1 is not shown in the content shown.

[0025] Figure 1c for Figure 1a The diagram shows another view of the device 1 after illuminating the second region 6b of the front side 2a of the silicon solar cell. In addition to the first contact unit 4a of the first contact device 4, the second contact unit 4b of the first contact device 4 has also made contact with a portion of the contact grid of the front side 2a of the silicon solar cell. For this purpose, the second contact unit 4b is placed on a portion of the contact grid within the second region 6b of the front side 2a. After the second contact unit 4b is placed on the surface, the point light source 3 is guided through a third region 6c of the front side 2a, located outside the first and second regions 6b. During this process, current flows in the silicon solar cell 2, particularly in the illuminating region, thereby improving the ohmic contact characteristics of the contact grid of the front side 2a of the single-sided silicon solar cell 2 (especially in the illuminating region).

[0026] Figure 1d According to Figure 1a The illustrated device 1 is shown in another view after illuminating the third region 6c of the front side 2a of the silicon solar cell. The first contact unit has been lifted away from a portion of the contact grid within the first region 6a of the front side 2a. The second contact unit 4b of the first contact device 4 remains positioned on a portion of the contact grid within the second region 6b of the front side 2a. In this contact state of the contact grid, the point light source is being guided through the first region 6a of the front side 2a.

[0027] To place the first contact unit 4a of the first contact device 4 onto the contact grid on the front side 2, the lever arm of the first contact unit 4a swings downward. To remove the first contact unit 4a from the contact grid on the front side 2, the lever arm of the first contact unit 4a swings upward. To place the second contact unit 4b of the first contact device 4 onto the contact grid on the front side 2, the lever arm of the second contact unit 4b swings downward. To remove the second contact unit 4b of the first contact device 4 from the contact grid on the front side 2, the lever arm of the second contact unit 4b swings upward.

[0028] The apparatus 1 and method described above are also applicable to the bifacial silicon solar cell 2. The bifacial silicon solar cell also employs a back contact in the form of a contact grid, rather than a planar back contact; therefore, a first contact grid is provided on the front side 2a, and a second contact grid is provided on the back side 2b. Thus, both the front side 2a and the back side 2b of the bifacial silicon solar cell 2 have solar active regions. The bifacial silicon solar cell 2 can be placed in the apparatus 1 described above such that either the first contact device 4 contacts the first contact grid on the front side 2a, and the second contact device 5 contacts the second contact grid on the back side 2b; or the second contact device 5 contacts the first contact grid on the front side 2a, and the first contact device 4 contacts the second contact grid on the back side 2b. Accordingly, in the first case, a point light source 3 illuminates the front side 2a of the bifacial silicon solar cell 2; in the second case, it illuminates the back side 2b. When processing the bifacial silicon solar cell 2 using the apparatus 1 and method described above, the ohmic contact characteristics of both the contact grid on the front side 2a and the contact grid on the back side 2b can be improved simultaneously.

[0029] Figure 2a This is a side view of the apparatus 1 of the present invention for improving the ohmic contact characteristics of the first contact grid on the front side 2a and / or the second contact grid on the back side 2b of the bifacial silicon solar cell 2.

[0030] and Figure 1a The device shown is different from device 1. Figure 2a In the embodiment of the device 1 shown in the invention, the second contact device 5 is no longer a fixed contact strip, but is designed to have a first contact unit 5a and a second contact unit 5b that are movable during illumination. This device 1 is particularly suitable for bifacial silicon solar cells, but can also be used for single-sided silicon solar cells 2.

[0031] according to Figure 2a When the first contact unit 4a of the first contact device 4 is placed on a portion of the first contact grid in the first region 6a of the front side 2a, the first contact unit 5b of the second contact device 5 is also placed on a portion of the second contact grid in the first region 6a of the back side 2b, and then the second region of the front side 2a of the bifacial silicon solar cell 2 is illuminated by the point light source 3.

[0032] according to Figure 2b When the second contact unit of the first contact device 4 is placed on a portion of the first contact grid in the second region 6b of the front side 2a, the second contact unit 5b of the second contact device 5 is placed on a portion of the second contact grid in the second region 6b of the back side 2b, and then the third region 6c of the front side 2a of the bifacial silicon solar cell 2 is illuminated by the point light source 3.

[0033] according to Figure 2c When the first contact unit 4a of the first contact device 4 is moved away from the contact grid portion within the first region 6a of the front side 2a, the first contact unit 5b of the second contact device will also be moved away from the contact grid portion within the first region 6a of the back side 2b. Subsequently, the first region of the front side 2a of the bifacial silicon solar cell 2 is illuminated with the point light source 3. Of course, if only the front side 2a of the bifacial silicon solar cell 2 is illuminated, it is not necessary to move the first contact unit 5b of the second contact device away from the contact grid portion within the first region 6a of the back side 2b.

[0034] according to Figures 2a to 2c In the illustrated embodiment, in addition to illuminating the front side 2a of the bifacial silicon solar cell 2 with the point light source 3, the back side 2b of the bifacial silicon solar cell 2 can also be illuminating with the point light source 3. Similarly, the front side 2a and the back side 2b of the bifacial silicon solar cell 2 can be illuminating simultaneously. For this purpose, another point light source 3 can be used, or the light emitted by the existing point light source 3 can be separated by a beam splitter, and the light can be guided by a reflector system to illuminate the front side 2a and the back side 2b respectively. In this case, it is more advantageous if the first contact unit 4a and the second contact unit 4b of the first contact device 4, and the first contact unit 5a and the second contact unit 5b of the second contact device 5, can be placed and removed on the first contact grid of the front side 2a or the second contact grid of the back side 2b of the silicon solar cell 2 when they are in the illuminating areas 6a and 6b respectively.

[0035] The first contact unit 5a and the second contact unit 5b of the second contact device 5 are designed as lever arms with conductive contact pads. By tilting their respective lever arms, they can be placed on the corresponding portions of the contact grid on the back side 2b of the silicon solar cell 2. To place the first contact unit 5a on the contact grid on the back side 2, the lever arm of the first contact unit 5a needs to be swung downwards. To remove the first contact unit 5a from the contact grid on the back side 2, its lever arm needs to be swung upwards. To place the second contact unit 5b on the contact grid on the back side 2, the lever arm of the second contact unit 5b needs to be swung downwards. To remove the second contact unit 5b from the contact grid on the front side 2, its lever arm needs to be swung upwards.

[0036] If the contact fingers of the contact gate are interconnected via busbars, then the contact units are preferably placed on these busbars, but the invention is not limited thereto.

[0037] according to Figure 3a and Figure 3b The illustrated embodiment of the device 1 for improving the ohmic contact characteristics of the contact grid on the front side 2a of a silicon solar cell includes 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 designed to contact the contact grid, and the second contact device 5 is designed to contact the back contact of the silicon solar cell 2. The voltage source is designed to apply a voltage in the opposite direction to the positive direction of the silicon solar cell 2 and less than the breakdown voltage of the silicon solar cell. The point light source 3 is designed to be guided through the solar active region of the front side 2a of the silicon solar cell when a voltage opposite to the positive direction of the silicon solar cell 2 is applied. The first contact device 4 has a first contact unit 4a and a second contact unit 4b. The first contact unit 4a is designed to be placed within and removable from a first region 6a of the front side 2a, representing a portion of the contact grid. The second contact unit 4b is designed to be placed within and removable from a second region 6b of the front side 2a, located outside the first region 6a. The point light source 3 is designed to be guided through the second region 6b of the front surface 2a when the first contact unit 4a is placed within a portion of the contact gate in the first region 6a of the front surface 2a and the second contact unit 4b is moved away from the portion of the contact gate in the second region 6b of the front surface 2a. Furthermore, the point light source 3 is also configured to be guided through the first region 6a of the front surface 2a when the first contact unit 4a is moved away from the portion of the contact gate in the first region 6a of the front surface 2a and the second contact unit 4b is placed within a portion of the contact gate in the second region 6b of the front surface 2a.

[0038] In the illustrated embodiment, the second contact device 5 consists of two contact strips that are attached to the back surface 2b of the silicon solar cell 2. The contact strips can be guided onto the back surface 2b of the silicon solar cell 2, or the back surface 2b of the silicon solar cell 2 can be guided onto the contact strips. Preferably, reliable contact between the contact strips and the back surface 2b is ensured by forming an adsorption between the contact strips and the back surface 2b of the silicon solar cell 2. The first contact unit 4a and the second contact unit 4b of the first contact device 4 are designed to... Figure 1b The implementation methods shown are similar.

[0039] To make the contact gate contact the first contact device 4, the first contact unit 4a of the first contact device 4 is first placed on a portion of the contact gate within the first region 6a of the front side 2a. After applying a voltage opposite to the conduction direction of the silicon solar cell 2, the point light source 3 is first guided through the second region 6b of the front side 2a, which is located outside the first region 6a. Subsequently, the second contact unit 4b of the first contact device 4 is placed on a portion of the contact gate within the second region 6b of the front side 2a, and the point light source 3 is guided through the first region of the front side 2a. At this time, the first contact unit 4a of the first contact device 4 has been removed from the portion of the contact gate in the first region 6a of the front side 2a.

[0040] and Figure 3a and Figure 3b The implementation shown is the opposite. Figure 3a and Figure 3b The illustrated embodiment shows a modified second contact device 5. The second contact device 5 includes a first contact unit 5a and a second contact unit 5b. The first contact unit 5a of the second contact device 5 is designed such that when the first contact unit 4a of the first contact device 4 is placed on a portion of the contact gate in the first region 6a of the front side 2a, it can also be placed on a portion of the contact gate in the first region 6a of the back side 2b. The first contact unit 5a of the second contact device 5 is designed such that when the first contact unit 4a of the first contact device 4 is moved away from the contact gate portion in the first region 6a of the front side 2a, it also moves away from the contact gate portion in the first region 6a of the back side 2b. The second contact unit 5b of the second contact device 5 is designed such that when the second contact unit 4b of the first contact device 4 is placed on a portion of the contact gate in the second region 6b of the front side 2a, it can also be placed on a portion of the contact gate in the second region 6b of the back side 2b. The second contact unit 5b of the second contact device 5 is designed such that when the second contact unit 4b of the first contact device 4 is moved away from the contact gate portion in the second region 6b of the front side 2a, it also moves away from the contact gate portion in the second region 6b of the back side 2b.

[0041] Apart from Figure 3a and Figure 3b In addition to the methods described in the text, Figure 4a and Figure 4bThe method shown also includes the following steps. When the first contact unit 4a of the first contact device 4 is placed on a portion of the first contact grid in the first region 6a of the front side 2a, the first contact unit 5b of the second contact device 5 is placed on a portion of the second contact grid in the first region 6a of the back side 2b. When the second contact unit of the first contact device 4 is placed on a portion of the first contact grid in the second region 6b of the front side 2a, the second contact unit 5b of the second contact device 5 is placed on a portion of the second contact grid in the second region 6b of the back side 2b. When the first contact unit 4a of the first contact device 4 moves away from the contact grid portion in the first region 6a of the front side 2a, the first contact unit 5b of the second contact device 5 also moves away from the contact grid portion in the first region 6a of the back side 2b. The design of the first contact unit 4a of the first contact device 4, the second contact unit 4b of the first contact device 4, the first contact unit 5a of the second contact device 5, and the second contact unit 5b of the second contact device 5 is consistent with... Figure 2a The implementation methods shown are similar.

[0042] Preferably, in the embodiment, the first contact unit 4a and / or the second contact unit 4b of the first contact device 4 and / or the first contact unit 5a and / or the second contact unit 5b of the second contact device 5 are movable relative to the silicon solar cell 2 in an electric or pneumatic manner, thereby enabling automation of the entire process.

[0043] List of symbols:

[0044] 1 device

[0045] 2. Silicon solar cells

[0046] 2a Front

[0047] 2b Back

[0048] 3 point light sources

[0049] 4 First contact device

[0050] 4a First contact unit of first contact device 4

[0051] 4b The second contact unit of the first contact device 4

[0052] 5 Second contact device

[0053] 5a The first contact unit of the second contact device 5

[0054] 5b Second contact device 5 second contact unit

[0055] 6a First Area

[0056] 6b Second Area

[0057] 6c Third Region

[0058] 7. Path of point light source 3 on silicon solar cell 1

[0059] The beam of light from point light source 3 of point 8

Claims

1. A method for improving the ohmic contact characteristics of the first contact grid on the front side (2a) of a single-sided or double-sided silicon solar cell, comprising firstly providing a silicon solar cell (2) having a first contact grid on the front side (2a) of the silicon solar cell (1) and a back contact body on the back side (2b) of the silicon solar cell (1), wherein the first contact grid is in contact with a first contact device (4) electrically connected to one pole of a voltage source, and the back contact body is in contact with a second contact device (5) electrically connected to the other pole of the voltage source, and applying a voltage opposite to the positive direction of the silicon solar cell (2) by the voltage source, the voltage value being less than the breakdown voltage of the silicon solar cell, and simultaneously guiding a point light source (3) through the solar active region on the front side (2a) of the silicon solar cell (2), characterized in that, To achieve contact between the first contact device (4) and the first contact grid, the first contact unit (4a) of the first contact device (4) is first placed on a portion of the first contact grid in the first region (6a) of the front side (2a), and after applying a voltage opposite to that of the silicon solar cell (2), the point light source (3) is first guided through the second region (6b) located outside the first region (6a) of the front side (2a); and subsequently, after the first contact unit (4a) of the first contact device (4) is moved away from the portion of the first contact grid in the first region (6a) of the front side (2a), the second contact unit (4b) of the first contact device (4) is placed on a portion of the first contact grid in the second region (6b) of the front side (2a), and the point light source (3) is guided through the first region (6a) of the front side (2a).

2. The method according to claim 1, characterized in that, After the guide point light source (3) passes through the first region of the front (2a) and before the first contact unit (4a) of the first contact device (4) moves away from a portion of the contact grid in the first region (6a) of the front (2a), the guide point light source (3) passes through the third region (6c) of the front (2a) outside the first region (6b) and the second region (6b).

3. The method according to claim 1 or 2, characterized in that, In the case of bifacial solar cells, the back contact of the back side (2b) of the silicon solar cell (1) is the second contact grid.

4. The method according to claim 3, characterized in that, When the first contact unit (4a) of the first contact device (4) is placed on a portion of the first contact gate on the front side (2a) of the first region (6a), the first contact unit (5b) of the second contact device (5) is placed on a portion of the second contact gate on the back side (2b) of the first region (6a); and when the second contact unit (4b) of the first contact device (4) is placed on a portion of the first contact gate on the front side (2a) of the second region (6b), the second contact unit (5b) of the second contact device (5) is placed on a portion of the second contact gate on the back side (2b) of the second region (6b).

5. The method according to claim 4, characterized in that, When the first contact unit (4a) of the first contact device (4) is moved away from the first contact gate portion in the first region (6a) of the front side (2a), the first contact unit (5b) of the second contact device is simultaneously moved away from the second contact gate portion in the first region (6a) of the back side (2b).

6. A method for improving the ohmic contact characteristics of a first contact grid on the front side (2a) and / or a second contact grid on the back side (2b) of a bifacial silicon solar cell (2), firstly providing a silicon solar cell (2) having two contact grids, wherein the first contact grid is in contact with a first contact device (4) electrically connected to one pole of a voltage source, the second contact grid is in contact with a second contact device (5) electrically connected to the other pole of the voltage source, and a voltage opposite to the positive direction of the silicon solar cell (2) is applied by the voltage source, wherein the voltage value is less than the breakdown voltage of the silicon solar cell, characterized in that... To achieve contact between the second contact grid and the second contact device (5), the first contact unit (5b) of the second contact device (5) is first placed on a portion of the second contact grid within the first region (6a) of the back surface (2b). After applying a voltage opposite to that of the silicon solar cell (2), the point light source (3) is first guided through the second region (6b) of the back surface (2b) located outside the first region (6a). Then, the second contact unit (5b) of the second contact device (5) is placed on a portion of the second contact grid of the back surface (2b) within the second region (6b). The point light source (3) is then guided through the first region of the back surface (2b) of the silicon solar cell (2). At this time, the first contact unit (5b) of the second contact device (5) has moved away from the portion of the second contact grid within the first region (6a) of the back surface (2b).

7. The method according to claim 6, characterized in that, After the guide point light source (3) passes through the first region of the back side (2b) and before the first contact unit (5a) of the second contact device (5) is removed from a portion of the second contact gate in the first region (6a) of the back side (2b), the guide point light source (3) passes through the third region (6c) of the back side (2b) located outside the first and second regions (6b).

8. The method according to claim 7, characterized in that, When the first contact unit (5b) of the second contact device (5) is placed in part of the second contact grid in the first region (6a) of the back side (2b), the first contact unit (4a) of the first contact device (4) is placed in part of the first contact grid in the first region (6a) of the front side (2a); and when the second contact unit (5b) of the second contact device (5) is placed in part of the second contact grid in the second region (6b) of the back side (2b), the second contact unit (4b) of the first contact device (4) is placed in part of the first contact grid in the second region (6b) of the front side (2a).

9. The method according to claim 8, characterized in that, When the first contact unit (5b) of the second contact device (5) is moved away from the second contact gate portion in the first region (6a) of the back side (2b), the first contact unit (4a) of the first contact device is simultaneously moved away from the first contact gate portion in the first region (6a) of the front side (2a).

10. An apparatus (1) for improving the ohmic contact characteristics of the contact grid on the front side (2a) of a silicon solar cell, wherein the apparatus (1) comprises a first contact device (4), a second contact device (5), a voltage source, and a point light source (3), wherein 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, wherein the first contact device (4) is designed to contact the contact grid, and the second contact device (5) is designed to contact the back contact of the silicon solar cell (2), wherein the voltage source is designed to apply a voltage opposite to the positive direction of the silicon solar cell (2), the voltage value being less than the breakdown voltage of the silicon solar cell, wherein the point light source (3) is designed to be guided through the solar active region on the front side (2a) of the silicon solar cell (2) when a voltage opposite to the positive direction of the silicon solar cell (2) is applied, characterized in that, The first contact device (4) has a first contact unit (4a) and a second contact unit (4b); and the first contact unit (4a) can be placed on a portion of the contact gate in the first region (6a) of the front side (2a) and can be removed from that portion; and the second contact unit (4b) can be placed on a portion of the contact gate in the second region (6b) of the front side (2a) and can be removed from that portion; and when the first contact unit (4a) of the first contact device (4) is placed on a portion of the contact gate in the first region (6a) of the front side (2a) and the contact unit (4b) is removed from that portion; When the second contact unit (4b) moves away from the contact gate portion in the second region (6b) of the front (2a), the point light source (3) can be guided through the second region (6b) of the front (2a); and when the first contact unit (4a) of the first contact device (4) moves away from the contact gate portion in the first region (6a) of the front (2a) and the second contact unit (4b) of the first contact device (4) is placed on a part of the contact gate in the second region (6b) of the front (2a), the point light source (3) can be guided through the first region (6a) of the front (2a).

11. The apparatus (1) according to claim 10, characterized in that, When the first contact unit (4a) is placed on a portion of the contact grid in the first region (6a) of the front (2a) and the second contact unit (4b) is placed on a portion of the contact grid in the second region (6b) of the front (2a), the point light source (3) is designed to be guided through the third region (6c) of the front (2a).

12. The apparatus (1) according to claim 10 or 11, characterized in that, The second contact device (5) has a first contact unit (5a) and a second contact unit (5b); and the first contact unit (5a) of the second contact device (5) is designed such that when the first contact unit (4a) of the first contact device (4) is placed on a portion of the contact grid in the first region (6a) of the front side (2a), it is placed on a portion of the first region (6a) of the back side (2b); and the first contact unit (5a) of the second contact device (5) is designed such that when the first contact unit (4a) of the first contact device (4) is moved away from the portion in the first region (6a) of the front side (2a), it is moved away from the first region (6a) of the front side (2a). The portion within the first region (6a) of the back side (2b); and the second contact unit (5b) of the second contact device (5) is designed such that when the second contact unit (4b) of the first contact device (4) is placed on a portion of the contact gate within the second region (6b) of the front side (2a), it is placed on a portion of the second region (6b) of the back side (2b); and the second contact unit (5b) of the second contact device (5) is designed such that when the second contact unit (4b) of the first contact device (4) is removed from the portion of the contact gate within the second region (6b), it is moved away from the portion of the second region (6b) of the back side (2b).

13. The apparatus (1) according to any one of claims 10 to 12, characterized in that, The first contact unit (4a) of the first contact device (4) and / or the second contact unit (4b) of the first contact device (4) and / or the first contact unit (5b) of the second contact device (5) and / or the second contact unit (5b) of the second contact device (5) are movable relative to the silicon solar cell (2) in an electric or pneumatic manner.

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