Solar cell test device for measuring the electrical characteristics of a solar cell

Abstract

The invention relates to a solar cell test device for measuring the electrical characteristics of a solar cell (1) with a top (10) and a bottom (11), comprising a transfer contact unit (14) configured to tap and transmit the first signals from the first contact strip (8) during a measurement, and a conductor (12) configured to tap and transmit the second signals from the second contact strip (9) during the measurement. The transfer contact unit (14) is configured to transmit signals tapped from the first contact strip (8) during the measurement to a side of the solar cell (1) opposite the first contact strip (8), on which the second contact strip (9) and the conductor (12) are arranged.The conductor (12) is configured either to carry the first and second signals, tapped from the second contact strip (9), together to the measuring device (3), or to be connected to the measuring device (3) via the transfer contact unit (14) on the side of the solar cell (1) on which it is located, so that the first and second signals are carried together to the measuring device (3) on the side of the solar cell (1) on which the second contact strip (9) is located. Alternatively, an amplifier (15) is provided, which is associated with the transfer contact unit (14) and the conductor (12) of the first contact strip (8) or the second contact strip (9), wherein the amplifier (15) is configured to receive the first and second signals during the measurement and to amplify the difference to be carried to the measuring device (3).

Description

[0001] The invention relates to a solar cell testing device for measuring electrical characteristics of a solar cell.

[0002] Solar cell test devices for measuring the electrical characteristics of a solar cell, also called flashers, are known. An example of such a device is described in Fig. 1. The Fig. The solar cell testing device shown in Figure 1 for measuring electrical characteristics of a solar cell 1 having a top side 10 and a bottom side 11 has a contacting device for contacting the solar cell 1, which has a first contact strip (not shown) for electrically contacting the top side 10 and a second contact strip (not shown) for electrically contacting the bottom side 11. Furthermore, it has a junction box 2 and a measuring device 3, which is designed to carry out the measurement of electrical characteristics of the solar cell 1. The first contact strip and the junction box 2 are connected via a first current (+) line 4 and a first voltage (+) line 6 or sense line, while the second contact strip and the junction box 2 are connected via a second current (-) line 5 and a second voltage (-) line 7 orSense line are connected, wherein all lines 4, 5, 6, 7 are designed as individual lines and are contacted at each first and second contact strip 8, 9 with a current contact of the contact strip and a sense contact of the contact strip (not shown). The polarities can also be reversed depending on the type of solar cell, e.g. whether it is an n-type or p-type silicon solar cell. The junction box 2 is connected to the measuring device 3 via a connecting line 13, which bundles the first and second lines 4, 5, 6, 7 into a single cable carrying the individual measuring lines 4, 5, 6, 7. The first and second signals, respectively, are transported from the first contact strip and the second contact strip to the measuring device 3 via the first and second lines 4, 5, 6, 7 and the connecting line 13.

[0003] The first and second signals are therefore tapped separately from each of the first and second contact strips by means of single-core cables, each as two first and second lines 4, 5, 6, 7. The first and second lines 4, 5, 6, 7 must be routed separately from the first contact strip and the second contact strip to the junction box 2, since the solar cell 1 to be contacted is located between them and is transported by means of a bogie or a linear transport device (not shown). This results in very large areas of the spanned conductor loops. The interference fields coupled into this spanned conductor loop have a detrimental effect on the first and second signals.

[0004] In an automated solar cell testing device, the bogie or the linear transport device transports the solar cells 1 one after the other with a holder provided for this purpose between the contacting unit so that the solar cell 1 to be tested can be electrically connected to the measuring device 3 from above and below by means of the first and second contact strips. As soon as the solar cell 1 to be tested is positioned for measurement, the contacting moves together symmetrically and presses spring contacts of the first and second contact strips onto the solar cell 1. Once the solar cell 1 is contacted, it can be illuminated, for example, using a light source, and a voltage ramp or a constant voltage is applied via lines 4, 5. The voltage actually applied to the solar cell 1 is read back via the voltage (+) and voltage (-) lines 6, 7. This measures the voltage actually applied to the solar cell 1.This is lower than the voltage applied to the measuring device 3, which, due to the non-negligible resistances of the lines 4, 5 and the contact resistances between the first and second contact strips and the contacts of the solar cell 1, causes a voltage drop, thus reducing the voltage actually fed into the solar cell 1. The current is conducted and measured on the current (+) and current (-) lines 4, 5. Electromagnetic interference fields, which are inevitably caused, for example, by the automation located in the immediate vicinity of the solar cell testing device, can inductively couple into the conductor loops of the first and second contact strips or lines 6, 7 and thereby impair the sensitive measuring voltages to an intolerable extent.

[0005] There is also a need for faster cycle times in solar cell production, which requires shorter measurement times. It is desirable to shorten the usual measurement time of 200 ms to, for example, 20 ms. However, it has been found that a shorter measurement time results in insufficient accuracy, particularly for voltage measurements. The insufficient accuracy, particularly for voltage measurements, is due to the fact that in order to achieve the shorter measurement time, the number of samples in the averaging process is reduced, which worsens the signal-to-noise ratio. Since averaging is a low-pass filter and the cutoff frequency is inversely proportional to the number of samples, higher frequencies are measured with shorter measurement times, with increasing bandwidth and more and more interference becoming visible because interference fields couple in better with increasing frequency.

[0006] It is an object of the present invention to provide a solar cell testing device with which a required measurement accuracy is achieved in a relatively short measurement time.

[0007] The object is achieved by a solar cell testing device having the features of patent claim 1 and a solar cell testing device having the features of patent claim 8. Advantageous further developments and modifications are specified in the subclaims.

[0008] The invention is based on the basic idea that the first and second signals of the line(s) are guided from the first and second contact strips in such a way that the spanned areas of the different potentials are minimal.

[0009] A shortened measurement time requires a higher bandwidth of the measurement electronics. This increased bandwidth also places greater demands on interference immunity, as interference coupling also increases with higher bandwidth. Fig. 1 are designed as single wires that extend from the connection box 2 to the first and second contact strips, the Fig. The measuring arrangement shown in Figure 1, together with the solar cell 1, which has a very low resistance, can be regarded as a coil with one turn. Under constant ambient conditions, e.g. an interfering magnetic field from a motor of a transport device, the voltage induced in the coil (induction voltage) increases with an increase in the coil area. In general, the induction voltage in a coil increases with the larger the cross-sectional area of ​​the coil, the higher the number of turns of the coil, the stronger the magnetic field changes, the faster the magnetic field changes, and the higher the bandwidth. Therefore, a larger cross-section of the area spanned by the first and second sense lines causes greater interference coupling than a smaller one. By means of the invention, fewer interference fields are coupled in by minimizing the spanned area of ​​the transfer contact unit and the sense line.

[0010] The basic idea of ​​the invention is therefore to prevent the coupling of interference fields into the conductor loop of the sense line(s) or to reduce it as much as possible by minimizing the effective conductor loop spanned across the solar cell measuring bed, i.e., the area of ​​the unshielded or unamplified sense signals. To this end, the first and second sense signals are routed via the shortest possible route to a transfer point, from which the line routing is shielded or from which the sense signals are amplified via an amplifier such that the harmful influences no longer have a significant impact.

[0011] Preferably, the first contact strip is an upper contact strip configured to electrically contact the upper side during the measurement and to tap the first signals, while the second contact strip is a lower contact strip configured to electrically contact the lower side during the measurement and to tap the second signals. The solar cell testing device can have a plurality of first contact strips and a plurality of second contact strips. It can, for example, have a plurality of first contact strips and / or a plurality of second contact strips configured to measure current or voltage.

[0012] The invention relates to a solar cell testing device for measuring electrical characteristics of a solar cell having a top side and a bottom side, comprising - a measuring device designed to measure electrical characteristics of the solar cell, - a contacting device comprising a first contact strip designed to electrically contact one of the top or bottom sides during the measurement and to pick up first signals, and a second contact strip designed to electrically contact the other of the top or bottom sides and to pick up second signals, - a transfer contact unit designed to pick up and transport the first signals from the first contact strip during a measurement, - a line designed to pick up and transport the second signals from the second contact strip during the measurement, - wherein the transfer contact unit is designed to transport signals tapped from the first contact strip during the measurement to a side of the solar cell opposite the first contact strip, on which side the line is arranged, wherein the line is designed to transport the first and the second signals tapped from the second contact strip in a bundle to the measuring device, or is designed to be connected to the transfer contact unit in a bundle to the measuring device on the side of the solar cell on which it is arranged, so that the first and second signals are transported together on the side of the solar cell to the measuring device on which the second contact strip is located.

[0013] By tapping the signals from only one side of the solar cell, a short measurement time with sufficient accuracy is achieved. In particular, by tapping the sense signals from only one side of the solar cell, the area covered by the transfer contact unit and the sense line is minimized, thus achieving a short measurement time with sufficient accuracy. The first and second sense signals of the transfer contact unit and the sense line are routed in such a way that the areas covered by the different potentials are minimal.

[0014] The line is preferably a voltage or sense line, i.e. a line designed to conduct voltage, and the first and second signals are then preferably first and second sense signals, respectively. The solar cell testing device is designed to measure the solar cell by mechanically moving the first contact strip and the second contact strip onto the solar cell in order to make contact with it. In order to minimize the conductor loop spanning the sense signals between the first contact strip and the second contact strip, the first sense signals are routed via the transfer contact unit, which is located, for example, directly on the first contact strip or a few millimeters next to the solar cell, to the side of the solar cell on which the second sense line taps off the second sense signals from the second contact strip, and are tapped off from there. This reduces the conductor loop and reduces interference.

[0015] Position and direction specifications refer to a proper operating position of the solar cell test device including the solar cell to be tested. The bundled lines, preferably sense lines, are preferably arranged below the underside of the solar cell. The transfer contact unit preferably transports the first signals, preferably sense signals, on this side.

[0016] The transfer contact unit preferably has two electrical contacts or, more preferably, it consists of two electrical contacts, each located on or near the first contact strip on the first side of the solar cell. One electrical contact is preferably designed as a current contact, while the other electrical contact is preferably designed as a voltage contact. To transmit the current of the current line from the first contact strip to the second contact strip and the voltage of the sense line from the first to the second contact strip, two electrical current contact pins and two voltage (sense) contact pins are required, each located on opposite sides of the solar cell, i.e. one of the electrical current contact pins and one of the voltage (sense) contact pins is located on one or the opposite side of the solar cell.

[0017] The measuring device is preferably designed to apply a current or voltage to the contacting device. It is designed, for example, as a so-called SMU (Source Measure Unit).

[0018] The transfer contact unit is preferably designed as a contact pin that mechanically connects and electrically contacts the first contact strip and the second contact strip. The contact pin is, for example, a spring contact pin. One or both of the current and voltage contacts can be designed as a contact pin that mechanically connects and electrically contacts the first contact strip and the second contact strip. Preferably, each of the first and second contact strips is connected to both the current contact and the voltage contact.

[0019] In a preferred embodiment, the contact pin is designed to transfer the first signals to the second contact strip during the measurement, with the line being designed to transport the first and second signals from the second contact strip in a bundled manner to the measuring device. Since the differential signals are bundled via the transfer contact unit only millimeters away from the solar cell, this results in the smallest possible surface area and thus the lowest possible interference coupling.

[0020] In a preferred embodiment, the line is a sense line embodied as a coaxial cable having an inner conductor embodied to transport the first sense signals, and an outer conductor enclosing the inner conductor embodied to transport the second sense signals. By means of the coaxial cable, the first and second sense signals are transported via a single cable. The transfer contact unit can be an exposed part of the inner conductor. Preferably, the transfer contact unit is embodied as the contact pin that mechanically and electrically connects the first and second contact strips when the sense line is embodied as a coaxial cable. The inner conductor can then transport the first sense signals embodied by the transfer contact unit to the second contact strip, and the outer conductor can transport the second sense signals embodied by the second contact strip to the measuring device.

[0021] In a preferred embodiment, the transfer contact unit and the line—preferably the sense line—are twisted together on one side of the solar cell and routed to the measuring device on which the second contact strip is arranged. Preferably, the transfer contact unit and sense line are twisted together on one side below the second contact strip and routed to the measuring device. In this embodiment, the transfer contact unit is preferably designed as a sense line.

[0022] The lengths of the transfer contact unit and the line, preferably the sense line, should be kept as short as possible. The transfer contact unit preferably has a percentage share of up to 5.00% of the total line length, consisting of the line lengths of the contact unit and the lines, preferably the sense lines.

[0023] In a preferred embodiment, the solar cell testing device further comprises an amplifier associated with the transfer contact unit and the sense line of the first contact strip and the second contact strip, respectively. The amplifier is configured to receive the first and second sense signals during the measurement and to amplify the difference to be transmitted to the measuring device. The amplifier on or near the second contact strip amplifies the difference between the first and second sense signals and forwards it, thereby resulting in a better signal-to-noise ratio.

[0024] Furthermore, the invention relates to a solar cell testing device for measuring electrical characteristics of a solar cell having a top side and a bottom side, comprising: - a measuring device designed to measure electrical characteristics of the solar cell, - a contacting device comprising a first contact strip designed to electrically contact one of the top or bottom sides during the measurement and to pick up first signals, and a second contact strip designed to electrically contact the other of the top or bottom sides and to pick up second signals, - a transfer contact unit configured to transport the first signals from the first contact strip to the measuring device, and a line configured to transport the second signals from the second contact strip to the measuring device, - an amplifier which is assigned to the transfer contact unit and the line of the first contact strip or the second contact strip, wherein the amplifier is designed to receive the first and second signals during the measurement and to amplify the difference to be transported to the measuring device.

[0025] The design of the solar cell test device results in a better signal-to-noise ratio on the measuring device.

[0026] Preferably, the amplifier is arranged on and / or on or at a distance of less than 10 cm, preferably 5 cm, preferably 3 cm from the second contact strip

[0027] Two amplifiers can also be provided, one for voltage measurement and possibly another for current measurement. However, only one amplifier is preferably provided, which is designed to amplify the difference between the first and second voltage (sense) signals.

[0028] In a preferred embodiment, the transfer contact unit and / or the line, preferably the sense line, has or have a shield. This further increases measurement accuracy. The shield is designed, for example, as a multilayer PCB and / or edge plating.

[0029] The solar cell testing device preferably has a suitable number of first and second contact strips, transfer contact units, and lines to perform both a current measurement and a voltage measurement. The solar cell testing device is preferably designed to measure current and voltage, so that it has a current transfer contact unit and a voltage transfer contact unit as two transfer contact units of the upper contact strip, and a current line and a sense or voltage line as two lines of the lower contact strip.

[0030] Preferably, the solar cell testing device further comprises a light source configured to illuminate the solar cell during the measurement.

[0031] Preferably, the solar cell testing device further comprises a junction box which is connected between the measuring device and the transfer contact unit or line and which is designed to transport the first and second signals from the transfer contact unit or line in a bundled manner to the measuring device.

[0032] Various embodiments of the invention are illustrated purely schematically in the drawings and are described in more detail below. The drawings are schematic and not to scale: Fig. 1 a sketched representation of a solar cell testing device according to the prior art; Fig. 2 is a schematic diagram of a solar cell testing device according to a first embodiment; Fig. 3 is a schematic diagram of a solar cell testing device according to a second embodiment; Fig. 4 is a schematic diagram of a solar cell testing apparatus according to a third embodiment; Fig. 5 is a schematic diagram of a solar cell testing apparatus according to a fourth embodiment; Fig. 6 one with the Fig. 1 shown solar cell test device; Fig. 7 one with the Fig. 3 shown solar cell test device; and Fig. 8 one with the Fig. Measurement performed using the solar cell test device shown in Figure 4.

[0033] Fig. Figure 1 shows a schematic representation of a solar cell testing device according to the prior art. To describe the Fig. 1, reference is made to the introduction to the description above.

[0034] To measure characteristic values ​​of solar cell 1, the first and second contact strips are lowered onto solar cell 1 and subjected to a voltage ramp or a constant voltage, with a light source (not shown) possibly illuminating solar cell 1. The first and second sense lines 6, 7 pick up the first and second sense signals, respectively, and transport them to junction box 2, from which they are transported via connecting line 13 to measuring device 3.

[0035] Fig. Figure 2 shows a schematic representation of a solar cell testing device according to a first embodiment. Fig. The solar cell testing device shown in Figure 2 comprises a measuring device 3 configured to measure electrical characteristics of the solar cell 1, and a contacting device comprising a first contact strip 8 configured to electrically contact a top side 10 during the measurement and to tap first signals, and a second contact strip 9 configured to electrically contact the bottom side 11 and to tap second signals. Furthermore, the solar cell testing device comprises a transfer contact unit 14 configured to tap and transport the first signals from the first contact strip 8 during a measurement, and a line 12 configured to tap and transport the second signals from the second contact strip 9 during the measurement.The transfer contact unit 14 is designed to transport the first signals picked up by the first contact strip 8 during the measurement to a side of the solar cell 1 opposite the first contact strip 8, on which the line 12 is arranged. The line 12 is designed to transport the first and the second signals picked up by the second contact strip 9 in a bundled manner to the measuring device 3.

[0036] The first signals are, in particular, first sense signals, the second signals are, in particular, second sense signals, and line 12 is, in particular, designed as a sense line. Alternatively, the first and second signals can be current signals, and line 12 can be a current line.

[0037] To measure characteristic values ​​of the solar cell 1, the first and second contact strips 8, 9 are lowered onto the solar cell 1 and subjected to a voltage ramp or a constant voltage, with a light source (not shown) optionally illuminating the solar cell 1. The transfer contact unit 14 and the line 12 pick up the first and second signals from them, respectively. The transfer contact unit 14 transfers the first signals to the second contact strip 9. The line 12 picks up the first and second signals from the second contact strip 9 and transports the first and second signals in bundled form to the junction box 2, from where they are transported via the connecting line 13 to the measuring device 3.

[0038] Fig. 3 shows a schematic representation of a solar cell testing device according to a second embodiment. Fig. The solar cell test device shown in Figure 3 corresponds to the one shown in Fig. 2, with the difference that the line is a sense line 12 embodied as a coaxial cable. It has an inner conductor 12a configured to transport the first sense signals, and an outer conductor 12a surrounding the inner conductor, which is configured to transport the second sense signals. Furthermore, the sense line 12 has a shield 16 surrounding the outer conductor 12b.

[0039] To measure characteristic values ​​of the solar cell 1, the first and second contact strips 8, 9 are lowered onto the solar cell 1 and subjected to a voltage ramp or constant voltage, with a light source (not shown) possibly illuminating the solar cell 1. The transfer contact unit 14 and the sense line 14, 12 pick up the first and second sense signals from the contact strips 8, 9, respectively. The transfer contact unit 14 transfers the first sense signals to the second contact strip 9. The sense line 12 picks up the first and second sense signals from the second contact strip 9 and transports the first sense signals via the inner conductor 12a and the second sense signals via the outer conductor 12b to the junction box 2, from where they are transported via the connecting line 13 to the measuring device 3. The first and second sense signals are, for example, voltage sense signals.

[0040] Fig. Figure 4 shows a schematic diagram of a solar cell testing device according to the third embodiment. Fig. The solar cell test device shown in Figure 4 corresponds to the one shown in Fig. 2, with the difference that the transfer contact device 14 and the sense line 12 are twisted on one side of the solar cell to the measuring device 3. In this case, the transfer contact unit 14 and the sense line 12 are twisted below the underside of the solar cell 1 to the measuring device 3. The transfer contact device 14 has a section that is untwisted and is guided from the first contact strip 8 toward the second contact strip 9, so that from there the twisted transfer contact unit 14 and line 12 are guided to the junction box 2.

[0041] To measure characteristic values ​​of the solar cell 1, the first and second contact strips 8, 9 are lowered onto the solar cell 1 and subjected to a voltage ramp or a constant voltage, with a light source (not shown) possibly illuminating the solar cell 1. The transfer contact unit 14 and the sense line 12 pick up the first and second sense signals, respectively, from the contact strips 8, 9 and transport them to the junction box 2, from which they are transported via the connecting line 13 to the measuring device 3.

[0042] Fig. 5 shows a schematic representation of a solar cell testing device according to a fourth embodiment. Fig. The solar cell test device shown in Figure 5 corresponds to the one shown in Fig. 1, with the difference that it has an amplifier 15, which is assigned, for example, to the second contact strip 9. It can be located as close as possible to the solar cell 1 in order to keep the conductor loop small, alternatively, for example, between the solar cell 1 and the junction box 2. The amplifier 15 is assigned to the transfer contact unit 14 and the line 12, which is designed as a sense line, to the first contact strip 8 and the second contact strip 9, respectively. The amplifier 15 is designed to receive the first and second sense signals during the measurement and to amplify the difference to be transported to the measuring device 3.

[0043] To measure the characteristics of solar cell 1, the first and second contact strips 8, 9 are lowered onto solar cell 1 and subjected to a voltage ramp or constant voltage, with a light source (not shown) optionally illuminating solar cell 1. The transfer contact unit 14 and the sense line 12 pick up the first and second sense signals, respectively, and the amplifier 15 amplifies a difference between the first and second sense signals. This difference is transported to the junction box 2, from which it is transported via the connecting line 13 to the measuring device 3.

[0044] Fig. 6 shows one with the Fig. The measurement was performed using the solar cell test device shown in Figure 1. To measure the solar cell's characteristics, the first and second contact strips were lowered onto the solar cell and subjected to a constant contact voltage of 1 V. Five measurements were performed, each with and without interference in the form of a jammer. The standard deviation of each measurement was then calculated and averaged across the five measurements. The measurement without interference 17 serves as the reference. To determine the effect of interference, the reference is subtracted from the measurement with interference 18. This shows that the interference increases the standard deviation by 3952.22 µV.

[0045] Fig. 7 shows one with the Fig. 4 shown solar cell test device, wherein a voltage is measured as described above. Fig. 6. Five measurements were performed, each with and without interference in the form of a jammer. The standard deviation of each measurement was then calculated and averaged over the five measurements. The measurement without interference 17 serves as a reference. To determine the effect of interference, the reference is subtracted from the measurement with interference 18. This results in the interference coupling compared to the measurements in Fig. 6 measurement by 348 times compared to the one shown in Fig. 6 shown measurement is reduced.

[0046] Fig. 8 shows one with the Fig. 3 shown solar cell test device, wherein a voltage is measured as described above. Fig. 6. Five measurements were performed, each with and without interference in the form of a jammer. The standard deviation of each measurement was then calculated and averaged over the five measurements. The measurement without interference 17 serves as a reference. To determine the effect of interference, the reference is subtracted from the measurement with interference 18. This results in the interference compared to the measurement in Fig. 6 shown measurement is reduced. List of reference symbols: 1 solar cell 2 junction boxes 3 measuring unit 4 Power (+) line 5 Power (-) line 6 Voltage (+)-- line or sense line 7 Voltage (-) line or sense line 8 first contact strip 9 second contact strip 10 Top 11 Subpage 12 Line 13 connecting line 14 Transfer contact unit 15 amplifiers 16 Shielding device 17 Measurement without jammers 18 Measurement with jammer

Claims

[1] Solar cell test device for measuring electrical characteristics of a solar cell (1) with a top side (10) and a bottom side (11), comprising - a measuring device (3) designed to carry out the measurement of electrical characteristics of the solar cell (1), - a contacting device comprising a first contact strip (8) designed to electrically contact one of the top or bottom sides (10, 11) during the measurement and to pick up first signals, and a second contact strip (9) designed to electrically contact the other of the top or bottom sides (10, 11) and to pick up second signals, - a transfer contact unit (14) which is designed to pick up and transport the first signals from the first contact strip (8) during a measurement, - a line (12) which is designed to pick up and transport the second signals from the second contact strip (9) during the measurement, - wherein the transfer contact unit (14) is designed to transport signals picked up from the first contact strip (8) during the measurement to a side of the solar cell (1) opposite the first contact strip (8), on which side the line (12) is arranged, - wherein the line (12) is designed to transport the first and the second signals tapped from the second contact strip (9) in a bundled manner to the measuring device (3), or is designed to be connected to the transfer contact unit (14) in a bundled manner to the measuring device (3) on the side of the solar cell (1) on which it is arranged, so that the first and second signals are transported together on the side of the solar cell (1) to the measuring device (3) on which the second contact strip (9) is located. [2] Solar cell testing device according to claim 1, characterized by that the transfer contact unit (14) is designed as a contact pin which mechanically and electrically connects the first contact strip (8) and the second contact strip (9). [3] Solar cell testing device according to claim 2, characterized by that the contact pin is designed to transfer the first signals to the second contact strip (9) during the measurement, wherein the line (12) is designed to transport the first and second signals from the second contact strip (9) in a bundled manner to the measuring device (3). [4] Solar cell testing device according to claim 1 or 2, characterized by that the line (12) is designed as a sense line which is designed as a coaxial cable having an inner conductor (12a) which is designed to transport the first signals, and an outer conductor (12b) which surrounds the inner conductor (12a) and is designed to transport the second signals. [5] Solar cell testing device according to claim 1, characterized by that the transfer contact unit (14) and the line (12) are twisted on one side of the solar cell to the measuring device (3) on which the second contact strip (9) is arranged. [6] Solar cell testing device according to one of the preceding claims, characterized by that the transfer contact unit (14) has a line length with a percentage share of a total line length from the line lengths of the transfer contact unit and line (14, 12) which is up to 5%. [7] Solar cell testing device according to one of the preceding claims, characterized byan amplifier (15) which is assigned to the transfer contact unit (14) and the line (12) of the first contact strip (8) or the second contact strip (9), wherein the amplifier (15) is designed to receive the first and second signals during the measurement and to amplify the difference to be transported to the measuring device (3). [8] Solar cell test device for measuring electrical characteristics of a solar cell (1) with a top side (10) and a bottom side (11), comprising - a measuring device (3) designed to carry out the measurement of electrical characteristics of the solar cell (1), - a contacting device comprising a first contact strip (8) designed to electrically contact one of the top or bottom sides (10, 11) during the measurement and to pick up first signals, and a second contact strip (9) designed to electrically contact the other of the top or bottom sides (10, 11) and to pick up second signals, - a transfer contact unit (14) designed to transport the first signals from the first contact strip (8) to the measuring device (3), - a line (12) designed to transport the second signals from the second contact strip (9) to the measuring device (3), - an amplifier (15) which is assigned to the transfer contact unit (14) and the line (12) of the first contact strip (8) or the second contact strip (9), wherein the amplifier (15) is designed to receive the first and second signals during the measurement and to amplify the difference to be transported to the measuring device (3). [9] Solar cell testing device according to claim 7 or 8, characterized by that the amplifier (15) is arranged on and / or on or at a distance of less than 10 cm, preferably 5 cm, more preferably 3 cm from the first contact strip (8). [10] Solar cell testing device according to one of the preceding claims, characterized by that the transfer contact unit (14) and / or the line (12) has or have a shield (16). [11] Solar cell testing device according to one of the preceding claims, characterized bythat the transfer contact unit (14) is designed as a current or voltage line and / or the line (12) is designed as a current or voltage line. [12] Solar cell testing device according to one of the preceding claims, characterized by a light source designed to illuminate the solar cell during the measurement. [13] Solar cell testing device according to one of the preceding claims, characterized by a connection box (2) which is connected between the transfer contact unit (14) or line (12) and the measuring device (3) and is designed to transport the first and second signals in a bundled manner to the measuring device (3).

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