EP4176512A2

EP4176512A2 - Contacting device, solar-cell testing device and light source

Info

Publication number: EP4176512A2
Application number: EP21754909.6A
Authority: EP
Inventors: Maximilian Scherff
Original assignee: Wavelabs Solar Metrology Systems GmbH
Current assignee: Wavelabs Solar Metrology Systems GmbH
Priority date: 2020-07-06
Filing date: 2021-06-28
Publication date: 2023-05-10
Also published as: DE102020117760A1; WO2022007995A2; WO2022007995A3

Abstract

The invention relates to a contacting device for electrically contacting a solar cell (3) during the measurement of electrical characteristic data of the solar cell (3), which has a solar-cell surface (30), the contacting device comprising at least one measuring strip (1), which has at least one contact connection point for electrical contact with a solar-cell testing device and is designed to electrically contact the solar cell when the measuring strip (1) is placed onto the solar-cell surface (30), wherein the measuring strip (1) extends, in a longitudinal direction (L) running along the solar-cell surface (30), over a strip length (l), extends, perpendicularly to the longitudinal direction (L) away from the solar-cell surface in a transverse direction (Q), over a strip width (q), and has, perpendicularly to the longitudinal direction (L) and to the transverse direction (Q), a strip thickness (d) which is less than the strip length (l) and the strip height (q), characterized in that the transverse direction (Q) forms an angle (w) not equal to 90° with the solar-cell surface. The invention also relates to a solar-cell testing device for measuring electrical characteristic data of a solar cell (3), comprising the contacting device. The invention also relates to a light source (2) for the solar-cell testing device for measuring electrical characteristic data of a solar cell, comprising at least one lighting module (21).

Description

Contacting device, solar cell test device and light source Description:

The invention relates to a contacting device, a solar cell test device and a light source. In particular, the invention relates to a contacting device for making electrical contact with a solar cell when measuring electrical characteristics of the solar cell

Solar cell test device for measuring electrical characteristics of a solar cell, which has such a contacting device and a light source, and the light source for this solar cell test device. DE 102008038 184 A1 discloses a contacting device for making electrical contact with a solar cell when measuring electrical characteristics of the solar cell. During the measurement, the contacting device is designed to temporarily contact a solar cell that has a large number of finger electrodes that are formed on a solar cell surface. The contacting device has at least one measuring strip, which has at least one contact connection for making electrical contact with a solar cell test device and is designed to contact the multiple finger electrodes of the solar cell when the measuring strip is placed on the solar cell surface. The measuring bar is designed to intersect in a number of finger electrodes, along which

solar cell surface running longitudinal direction over a strip length, which extends perpendicularly to the longitudinal direction away from the solar cell surface in a transverse direction over a strip width and perpendicular to the longitudinal direction and the transverse direction has a strip thickness smaller than the strip length and the strip height. The at least one measuring bar can have a trapezoidal cross section, which is designed, among other things, in such a way that a shadow cast by the measuring bar in relation to the solar cell does not protrude beyond predetermined areas. The at least one measuring bar can also have a different shape, e.g. B. with have a rectangular cross-section, provided they cause no or only minimal shading of the light-active surface of the solar cell. The measuring bars are always arranged perpendicularly to the solar cell surface, so that the transverse direction forms an angle of 90° with the solar cell surface, and the bar thickness is in the range of only a few millimeters and the bar height is in the range of a few centimeters in order to minimize shadowing effect in the measurement.

In addition to the contacting device, the solar cell test device has a light source which is intended to cast as little shadow as possible on the solar cell to be tested. The light source is designed to illuminate the solar cell during the measurement. If the light source is a point light source, the problem arises that the measuring strips, which contact the solar cell during illumination, produce a hard, undesirable shadow on one side. This shadow creates an inhomogeneous generation of charge carriers in the solar cell, which does not occur during operation and accordingly falsifies the electrical characteristics of the solar cell during the measurement. This should be avoided, since the total shaded area increases with the number of measuring bars.

In addition, as the number of measuring bars increases, the outer measuring bars move further and further outwards, with the result that the proportion of light falling obliquely on the measuring bar increases and the outer shadows widen. A similar effect occurs when the light source is flat. Here, however, the width of the shadows not only depends on the position of the measuring bar, its height and the distance from the light source, but also on the width of the light source. In addition, a shadow appears on both sides of the gauge bars, which becomes stronger towards the gauge bar and is asymmetrical.

A light source for use in the solar cell test device is known, for example, from WO 2012/098019 A1. The light source has a lighting module with a plurality of light generating units, each of the Light generating units has at least one semiconductor light source with a downstream, light-focusing primary optics. Furthermore, the lighting module has light-homogenizing secondary optics downstream of the light generation units and imaging tertiary optics downstream of the secondary optics, with the semiconductor light sources generating light in a plurality of separately controllable wavelength ranges.

The light source may include LEDs (Light Emitting Diodes) as light generating units. In order to be able to guarantee the spectra required by standards, LEDs of different wavelength ranges must be used. These also include those that have a comparatively poor degree of efficiency, which increases the number required. As a result, and due to the optical system required for each LED, the surface area of the light source increases, which is disadvantageous for the shadows cast. Moving the LEDs closer together is only possible to a limited extent due to the required optical system and physical limitations. In order to create narrower shadows, the light source would have to be further away (many meters) from the solar cell, which is not desirable or even possible. The amount of shadow cast would then be a function of installation conditions, which is also undesirable.

There is therefore still a need to ensure the most homogeneous possible illumination of the solar cell when measuring electrical characteristics of the solar cell. It is therefore an object of the invention to provide a contacting device, a solar cell test device and a light source in which a more homogeneous illumination of the solar cell is achieved when measuring electrical characteristics of the solar cell.

The object is achieved by a contacting device having the features of patent claim 1, a solar cell test device having the features of patent claim 8 and a light source having the features of patent claim 13. Advantageous developments and modifications are specified in the dependent claims. When using the contacting device, the solar cell test device and/or the light source, shading of the solar cell during the measurement of electrical characteristics of the solar cell is eliminated or at least reduced. In particular, a shadow cast is eliminated or at least reduced, which is caused by light from the light source striking the measuring bar at an angle.

The invention relates to a contacting device for making electrical contact with a solar cell when measuring electrical characteristics of the solar cell, the solar cell having a solar cell surface. The contacting device has at least one measuring strip, which has at least one contact connection for making electrical contact with a solar cell test device and is designed to make electrical contact with the solar cell when the measuring strip is placed on the solar cell surface. The measuring bar extends in a longitudinal direction, which runs along the solar cell surface. And it extends over a bar length. The measuring bar also extends perpendicularly to the longitudinal direction away from the solar cell surface in a transverse direction over a bar height. Finally, the measuring strip extends perpendicularly to the longitudinal direction and the transverse direction over a strip thickness that is smaller than the strip length and the strip height. In other words, the slat length, slat height, and slat thickness are each measured along directions all three of which are perpendicular to one another.

If the solar cell is designed with several or a large number of finger electrodes on the solar cell surface, the contacting device should be designed in such a way that the measuring strip makes electrical contact with at least some or all of the finger electrodes when the measuring strip is placed on the solar cell surface. In this case, the measuring bar can be designed to cross the finger electrodes. This means that the longitudinal direction runs at an angle to the finger electrodes, which are preferably arranged parallel to one another. In other words, the gauge crosses some or all finger electrodes. Alternatively, it can be provided that the measuring strip runs along a finger electrode and thus the longitudinal direction runs parallel to the finger electrode or electrodes.

According to the invention, it is provided that the transverse direction forms an angle with the solar cell surface that deviates from 90°. This is realized in particular in that the at least one measuring strip is inclined and not arranged perpendicular to the solar cell surface. In particular, when used in the solar cell testing device, the measuring bar is inclined toward the center of the light source used in the measurement with the contacting device. This further reduces the shadow cast during the measurement. In the case of the angle, one can also speak of an angle of inclination of the measuring bar on the solar cell surface.

The measuring bar is designed to extend in a longitudinal direction crossing several of the finger electrodes and running along the solar cell surface over a bar length, which extends perpendicularly to the longitudinal direction away from the solar cell surface in a transverse direction over a bar width. The transverse direction and the longitudinal direction are vectors that span the measuring bar, with the transverse direction running perpendicular to the longitudinal direction, so that the angle is not in the plane of the measuring bar, but in particular in a plane perpendicular to the measuring bar.

In a preferred embodiment, the measuring bar has a bar thickness in the range of 0.1 to 5 mm, or 0.5 to 4 mm, or 1 to 3 mm. In this way, relatively little optical shadowing of the solar cell surface is achieved when measuring the electrical characteristics of a solar cell using the contacting device. The measuring bar is preferably up to 3mm thick.

Their bar thickness can be adjusted according to the solar cells to be tested.

The measuring strip is preferably formed from sheet metal. The material of the measuring bar is preferably an electrically conductive material metal or metal alloy. The metal or metal alloy is preferably corrosion-resistant and has good electrical conductivity. The measuring strip is preferably a metal sheet. The material is preferably selected from the group consisting of copper and copper alloys such as Cu, CuBe2, CuZn37 and CuSn6. The modulus of elasticity of the material is preferably in the range of 70000-210000 N/mm ² , measured according to DIN EN ISO 6892-1:2017-02. Furthermore, the material preferably has a yield point in the range of ^{140-1500 N/mm 2} , measured according to DIN EN ISO 6892-1:2017-02. The metal sheet can be provided with an electrically insulating layer.

In a particular embodiment, the measuring strip can have contact spring sections on its underside, with which it contacts the finger electrodes of the solar cell. In particular when the measuring strip is designed as a metal sheet, the contact spring sections which are designed in one piece with the measuring strip can be cut out and/or punched out of this metal sheet in the form of wires. In this case, the modulus of elasticity and the yield point, which can be selected as described above for the measuring strip, determine the spring force and the maximum spring deflection of the contact spring sections.

In a preferred embodiment, the angle between the transverse direction and the solar cell surface is in a range between 81° and 88° or between 83° and 86°. This ensures that optical shadowing of the solar cell surface is eliminated or at least minimized when measuring the electrical characteristics using the contacting device.

The angle between the transverse direction and the solar cell surface preferably varies along the longitudinal direction. The angle between the transverse direction and the solar cell surface preferably varies along the longitudinal direction in that edge areas of the measuring bar are more inclined than a central area of the measuring bar. This embodiment is special advantageous when using the contacting device in a solar cell test device that has a relatively small (point) light source and/or that does not have a parabolic mirror or the like to generate parallel light. In the event that the angle of inclination of the measuring bar varies along the longitudinal direction, it can, strictly speaking, be assumed that an underside or bottom edge of the measuring bar resting on the solar cell surface extends in a straight line along the longitudinal direction.

In a preferred embodiment, the angle between the transverse direction and the solar cell surface decreases along the longitudinal direction from a central area of the measuring bar to an edge area of the measuring bar. This is realized, for example, in that a measuring strip area is all the more inclined the further out the measuring strip area is located. Or to put it another way: the angle varies between the transverse direction and the solar cell surface along the longitudinal direction in such a way that edge areas of the measuring bar are more inclined than a central area of the measuring bar. The angle preferably varies in the edge areas and middle areas in such a way that it is not equal to 90° and decreases along the longitudinal direction from a middle area of the measuring bar to an edge area of the measuring bar.

In a preferred embodiment, the contacting device also has one or more additional measuring strips. The measuring bar and the other measuring bar(s) preferably extend in the longitudinal direction, are spaced apart from one another along the solar cell surface and extend perpendicularly to the longitudinal direction away from the solar cell surface in a transverse direction assigned to the respective measuring bar, with the transverse directions being at least two, three or cross all measuring bars in pairs. This means that the transverse directions of the measuring strips are not, or at least not all, parallel to one another. The measuring strip and the further measuring strip(s) preferably extend parallel to one another in the longitudinal direction. In particular, this means that the lower edges of the measuring strips resting on the solar cell surface extend parallel to one another. Each measuring bar can have current-carrying and voltage-measuring contacts. In particular, this allows the 4-wire measurement technique that is customary in solar cell characterization to be used to read out the electrical characteristics of the solar cell. If the measuring bar is formed from sheet metal, it can also be a sheet stack made of sheets insulated from one another. The electrical insulation is realized, for example, by means of a sufficiently electrically insulating film or by paper, which is arranged over a surface area between the at least two metal sheets of a measuring strip. In the case of solar cells that are sensitive to the light radiation on both sides (so-called bifacial solar cells), contact strips on the back of the solar cell can also be used in the solar cell characterization, which are then inclined towards the center of a light source on the back.

The transverse directions of at least two of the measuring bars cross and are therefore not parallel. The transverse direction of one or more of the other measuring strips can form an angle of 90° with the solar cell surface. The measuring bar and the other measuring bar(s) form different angles to the solar cell surface and therefore have different inclinations and different transverse directions to the solar cell surface.

The transverse direction of a further measuring strip arranged centrally in the contacting device preferably forms an angle of 90° with the solar cell surface, ie it is arranged perpendicularly to the solar cell surface. The angle formed between the transverse direction and the solar cell surface preferably decreases the further away the measuring strip is from the center of the contacting device; i.e. the more inclined it is in relation to the solar cell surface.

A total number of measuring strips and further measuring strips, ie the number of measuring strips used, can depend, for example, on which types of solar cells are to be tested with the contacting device. Nowadays, solar cells with three to twelve or possibly more busbars are in production. The contacting device is preferably designed in such a way that each busbar is contacted by a (further) measuring strip during the measurement. There are also solar cells that only have finger electrodes and do not have a busbar. In this case, the measuring bar can contact all finger electrodes and act like a busbar. The contacting device is therefore alternatively preferably designed in such a way that each finger electrode is contacted with a (further) measuring strip during the measurement. The angle or the angle of inclination of the measuring strips preferably decreases from measuring strip to measuring strip towards the outside, as seen from the center of the solar cell. That is to say, the further out the (further) measuring strip is, the more inclined it is preferably and the smaller the angle that its transverse direction forms with the solar cell surface. Solar cells that do not have finger electrodes are also conceivable. For example, the solar cell surface can be provided with an electrically conductive anti-reflection layer. The measuring strip can then make electrical contact with the solar cell simply by placing it on the solar cell surface. In particular, it can be aligned along a solar cell edge of the solar cell, so that the longitudinal direction accordingly runs parallel to the solar cell edge. The at least one (further) measuring bar can have one or more

Have contact connections. The (additional) measuring strip(s) preferably have at least two contacts which are electrically insulated from one another. According to an advantageous embodiment, the measuring strip itself is not electrically conductive. Alternatively, if necessary, it can itself be electrically conductive. Each measuring strip preferably includes or consists of electrically insulating material into which contact pins are introduced which contact the solar cell and are electrically connected to one another and are then connected to measuring electronics. A measuring current is passed through these contact pins when measuring the characteristic curve of the solar cell. It is also possible that some of the contact pins are connected to one another separately, through which the measurement current does not flow but with which a cell voltage is measured precisely on the solar cell. In addition, the solar cells can also be divided for the measurement, for example halved, divided into thirds, etc., and the various parts can be measured at the same time. For this purpose, the (additional) measuring strips are divided electrically accordingly and the number of contact connections is adjusted accordingly. The (additional) measuring strip can therefore also have more than two contact connections, typically a multiple of two connections.

The invention also relates to a solar cell test device for measuring electrical characteristics of a solar cell, with a contacting device according to one or more of the embodiments described above and a light source which is designed to illuminate the solar cell surface during measurement of the electrical characteristics. Preferably, the angle is in a range between one

Minimum angle of incidence and a maximum angle of incidence, which are formed at the position of the measuring bar between the light beams emanating from the light source and the solar cell surface when the solar cell surface is illuminated.

The definitions of the minimum angle of incidence and the maximum angle of incidence are based on the basic idea that a light ray emanates from every point of the light source to every point on the solar cell. The angle, ie the angle of inclination of the measuring bar, is selected at least in such a way that the least possible shadow is cast in an angular range of these light beams due to the measuring bar. This is the case when the angle of inclination of the measuring bar essentially corresponds to the angle of incidence of the light rays on the solar cell surface at the position of the measuring bar.

In a preferred embodiment, the light source extends in the longitudinal direction over a light source length which is greater than a light source width over which the light source extends in a width direction extends perpendicular to the longitudinal direction and parallel to the solar cell surface. A light source with a linear structure is thus provided. This further reduces shadowing.

Preferably, the light source length is at least 1.5 times, 2 times, 3 times, 4 times, 5 times, 10 times, 50 times, 100 times, 200 times or 400 times as large as that light source width. A larger ratio between light source length and light source width emphasizes the linear character of the light source more clearly.

In a preferred embodiment, the light source is composed of several light modules. Due to the modular structure of the light source, it is flexible and can be retrofitted. The modular structure is preferably such that the length of the light sources in particular can be changed. As a result, the linear structure of the light source is further enforced.

The invention thus also relates to a light source for a solar cell test device for measuring electrical characteristics of a solar cell, with at least one light module which has a plurality of light generation units with primary optics, secondary optics and tertiary optics. Each of the light generating units has at least one illuminant with a downstream, light-bundling primary optics. The secondary optics is light-homogenizing and downstream of the light-generating units. The secondary optics are followed by the tertiary optics. It is an imaging optics.

The light source is preferably a semiconductor light source. However, other light sources can also be used, for example fluorescent tubes. Although semiconductor light sources are mentioned below as illuminants, the embodiments described below apply to any type of illuminant. The semiconductor light sources generate light in several separately controllable wavelength ranges. According to the invention, it is provided that the secondary optics and/or the tertiary optics fill a luminous surface which extends along a first direction over a light source length and along a second direction perpendicular thereto over a light source width, the light source length being at least 1.5 times, 2 times , 3 times, 4 times or 5 times the width of the light source. The luminous surface is therefore a surface of the light source from which the light is emitted. The light emitted by the light source from the luminous surface preferably fills the entire solar cell surface as completely and as uniformly as possible.

The light source is linear or elongated. As a result, shadows can be further reduced when using the light source in the solar cell test device. It is irrelevant whether the

Light source is used together with the contacting device described above or another contacting device. With a combination of the light source according to the invention with the contacting device according to the invention, however, the shadow-reducing effect is intensified.

The design of the light source is based on the basic idea of making it as narrow as possible in a first dimension, specifically in an extent that causes the shadow to be cast, and making it as wide as possible in a second dimension. An extreme embodiment of this is a strip-shaped or line-shaped light source.

The primary optic is preferably a collimator lens. The secondary optics is preferably a microlens. The tertiary optics is preferably a Fresnell lens. The primary, secondary and tertiary optics form an optical system consisting of three stages, which initially focus the light from each individual semiconductor light source using primary optics onto, for example, a microlens as secondary optics. The secondary optics ensure that the light of each semiconductor light source the area to be illuminated is evenly distributed, so that even with inhomogeneous semiconductor light source distribution or inhomogeneous semiconductor light source intensity distribution, homogeneous illumination is guaranteed at a defined distance. The subsequent tertiary optics focus the light beam onto the solar cell. Each semiconductor light source is preferably in the form of an LED (light-emitting diode).

In the solar cell test device, the light source can be aligned perpendicularly to or in the direction of the solar cell surface of the solar cell to be tested. The optical system of the light source can be adjusted accordingly. The solar cell test device can have multiple light sources.

The long and narrow, i.e. linear, light source will reduce or eliminate the shadows. The oblique incidence of light on the solar cell surface only occurs in the alignment of the (further) measuring bars and does not produce any shadows.

The light source influences the shadows not only in relation to the contacting device according to the invention but also in relation to commercially available contacting devices. The shadow produced is similar to the shadow produced by a point light source. When using a point light source, a 100% drop shadow with a width X is always realized. The width X increases the more the measuring strips are shifted outwards at an angle of 90° on the solar cell surface. Due to the increasingly acute angle of incidence of light, the shadow grows by an additional amount Y when using the point light source on the edge areas of the measuring bars or corners of the usually rectangular, especially square, solar cell. The area Y is always a 100% cast shadow, is in the middle of the bar equals zero and has its highest value at the edge of the bar. With the (ideally linear) light source according to the invention, when it is aligned parallel to the measuring bars with an angle of 90° formed by the transverse direction to the solar cell surface, the shadow in width X is just as wide as with the point light source and also a 100% cast shadow . However, the width Y is always the same width along the gauge, starting at 100% at the end of the X shadow and then decreasing to the edge of Y to 0% shadow. As a result, the measurement conditions in the corners of the solar cell are the same as in the middle of the measuring bar. Anywhere along the measuring bar beyond the area X, where there is no longer a shadow, at least some charge carriers would be generated in the solar cell during the measurement, which is not the case with the point light source in the corners of the solar cell.

This means that the area of total shadowing is narrower and more homogeneous over the length of the measuring bar. As a result, the shadow cast is minimized and relatively homogenized by means of the light source according to the invention, even in the case of measuring bars whose transverse direction forms an angle of 90° with the solar cell surface.

The luminous surface extends along a first direction over a light source length and along a second direction perpendicular thereto over a light source width. The luminous area is an area in which light is generated to illuminate the solar cell. The length of the light source and the width of the light source form a luminous plane. The luminous plane is preferably a plane of the light source. The secondary optics and/or the tertiary optics preferably fill the luminous surface perpendicular to the light emission direction. The light emission direction is preferably the direction of the line of the shortest connection between the light source and the solar cell.

When used in the solar cell test device with the contact device according to the invention, the light source is preferably designed and aligned in such a way that the measuring strip(s) are inclined towards the light source at the edges, in particular towards the center of the light source. This is preferred realized in that the angle between the transverse direction and the solar cell surface varies along the longitudinal direction.

The length of the light source is preferably at least 10 times, 50 times, 100 times, 200 times or 400 times the size of the light source width. This ensures the linear structure of the light source.

In a preferred embodiment, the light source also has at least one additional lighting module, the lighting module and the additional lighting module being arranged next to one another along the length of the light source. Despite this linear arrangement, the light fields generated by individual light modules are not projected side by side. This prevents inhomogeneities that usually occur in the otherwise occurring transition areas. The individual lighting modules are arranged and/or designed in such a way that their light is projected onto the same surface. This can be achieved, for example, with the help of "shift technology", i.e. a shifted Fresnel lens or by tilting the light sources on both sides, so that inhomogeneities caused by different distances are compensated. The linear arrangement of the light modules reduces shadows. The individual lighting modules can be designed identically. The modular design allows for a low-cost basic version that can be easily upgraded, also in terms of intensity and spectrum. The modular structure is also scalable in terms of intensity. The shading on the measuring strips does not increase through linear scaling, but the scaling does not necessarily have to be linear if an optical axis of the tertiary optics is adjusted accordingly.

In order to increase the intensity, for example in the light module of the basic version, only another tertiary optics with a shifted optical axis can be used and another light module can also be provided, which is also equipped with such a tertiary optics. An additional light module with the required wavelength ranges can also be used to spectrally upgrade the basic version to be provided. The modular character of the light source has the advantage that, for example, a first lighting module can be used initially, which generates light in a specific first wavelength range. A second light module can then be added to this first light module along the longitudinal direction, which light module generates light in a specific second wavelength range. The optics then ensure that light of both wavelength ranges is distributed homogeneously on the solar cell surface. The basic version of the light source according to the invention can consist, for example, of one or two light modules, which is or are equipped in such a way that it tends to deliver a relatively high intensity in powerful and inexpensive wavelength ranges and, on the other hand, in the expensive, low-power ranges such as UV, IR and Wavelength ranges delivers relatively little. Such a light source is inexpensive and only relatively little waste heat is produced. Due to the modular design, the basic version can be adapted and/or expanded at any time, which may be necessary, for example, if a measurement with higher intensity is required or the cell area of the solar cell to be tested is larger. Preferably, the light source and / or

Basic version LEDs with a relatively high efficiency. As a result, a relatively small or no heat sink is required for the light source, which generates heat during operation. In addition, the light source is cheaper. The modular design also allows cameras such as EL (electroluminescence) and IR (infrared) cameras to be positioned between the light modules or centrally on the sides of the light source and thus relatively close to the center of the light source. The lighting module and the further lighting module are preferably designed and/or arranged in such a way that the light they emit is parallel to and spaced from the lighting plane in an illumination plane essentially completely overlapped. The plane of illumination is preferably a plane of the solar cell surface that is illuminated by the light source.

The light-emitting module preferably has a light-emitting surface and the further light-emitting module has a further light-emitting surface, a perpendicular crossing perpendicular to the luminous surface and a further perpendicular crossing perpendicular to the further luminous surface. This means that the two luminous surfaces do not run in the same plane or in parallel planes. By arranging the two light modules at different angles, they can be aligned in such a way that they both illuminate and fill the entire solar cell surface.

An alternative arrangement for the purpose that each of the two light modules fills the solar cell surface is that the light modules point in the same direction, i.e. that both light surfaces are either in the same plane or at least parallel to one another, but that the light modules or the light you generate experiences a shift effect due to a subsequent tertiary optics, so that the light module and the other light module fill the same area at the level of the solar cell.

Various exemplary embodiments of the invention are shown purely schematically in the drawings and are described in more detail below. It shows schematically and not to scale

1 is a perspective view of one according to the invention

Solar cell testing device having a solar cell to be tested;

Fig. 2 is a side view of the solar cell testing device shown in Fig. 1 with the solar cell to be tested;

3a, 3b, 3c each show side views of a measuring bar which is arranged at different angles on the solar cell to be tested;

4 is a side view of another embodiment of the invention

Solar cell testing device having a solar cell to be tested; 5 is a perspective view of still another solar cell testing device according to the present invention having a solar cell to be tested; and FIG. 6 shows a partial side view of an arrangement with a solar cell illuminated by a light source.

1 schematically shows a perspective view of a solar cell test device according to the invention with a solar cell to be tested. The solar cell test device is provided for measuring electrical characteristic data of the solar cell 3 , which has a large number of finger electrodes 32 on a solar cell surface 30 . The solar cell test device has a light source 2 according to the invention and a contacting device according to the invention.

The light source 2 is designed to illuminate the solar cell surface 30 during the measurement of the electrical characteristic data. It has a lighting module 21 . The light-emitting module 21 has a plurality of light-generating units (not shown). Each of the light generation units has at least one semiconductor light source (not shown) with a downstream, light-bundling primary optics (not shown). Furthermore, the light-emitting module 21 has a den

Light generating units downstream, light-homogenizing secondary optics (not shown) and the secondary optics downstream, imaging tertiary optics (not shown). The secondary optics and/or the tertiary optics fill out a luminous surface which extends along a first direction over a light source length and along a second direction perpendicular thereto over a light source width. The length of the light source (not shown) is several times greater than the width of the light source (not shown), so that the light source 2 is linear. The semiconductor light sources generate light in several separately controllable wavelength ranges. Generated light beams are indicated by arrows. The secondary optics scatter the generated light in such a way that each light module illuminates the entire solar cell homogeneously. If, for example, a light module fails, the entire intensity decreases homogeneously over the solar cell surface. The solar cell test device also contains the contacting device according to the invention. The contacting device has a measuring bar 1, which has at least one contact connection (not shown) for making electrical contact with the solar cell test device and is designed to contact the multiple finger electrodes 32 when the measuring bar 1 is placed on the solar cell surface 30, which is shown here. The measuring bar 1 extends in a longitudinal direction L crossing the finger electrodes 32 and running along the solar cell surface 30 over a bar length l. It also extends perpendicularly to the longitudinal direction L away from the solar cell surface 30 in a transverse direction Q over a strip height q and has a strip thickness d perpendicular to the longitudinal direction L and the transverse direction Q, which is smaller than the strip length l and the strip width q . The transverse direction Q forms an angle with the solar cell surface 30 that deviates from 90°. As a result, the measuring strip 1 is not arranged vertically, but at an angle or inclined to the solar cell surface 30 . The angle or angle of inclination w is not shown in FIG. However, it can be seen that the measuring bar 1 does not lie perpendicularly on the solar cell surface 30 but is inclined towards the light source 2 . The measuring strip 1 has a strip thickness d of 2 mm, for example.

Furthermore, the contacting device--purely as an example two--further measuring strips 12; 13 on. The measuring bar 1 and the other measuring bars 12; 13 extend in the longitudinal direction L and are spaced apart from one another perpendicularly to the longitudinal direction along the solar cell surface 30 . The further measuring strip 12 has a transverse direction (not shown) which forms a further angle (not shown) with the solar cell surface 30 which is equal to 90°. The further measuring strip 13 has a transverse direction (not shown) which forms a further angle (not shown) with the solar cell surface 30 which deviates from 90°. The further measuring bar 13 and the measuring bar 1 are inclined towards one another in a mirror-inverted manner. The transverse directions of the three measuring bars 1, 12, 13 cross in the area of the light source 2. FIG. 2 shows an enlarged side view of the solar cell test device shown in FIG. 1 with the solar cell to be tested, the light source not being shown. The transverse direction (not shown) forms an angle w with the solar cell surface 30 which is less than 90° and is, for example, 87° or less. The impingement of the light generated by the light source on the solar cell surface 30 is indicated by dashed arrows.

3a, 3b, 3c each show a measuring strip 1 which rests on the solar cell 3 to be tested at different angles w. For purposes of illustration, a light beam emanating from the light source and impinging on the solar cell surface 30 is shown as an arrow in each of the three figures.

3a shows a measuring strip 1 which lies perpendicularly, ie at an angle w of 90°, on the solar cell surface 30. FIG. The measuring bar 1 therefore has a transverse direction that forms an angle of 90° with the solar cell surface 30 . A light beam generated by the light source, which is indicated by an arrow, produces a shadow with a relatively large shadow-casting width s. This arrangement is therefore undesirable.

3b shows a measuring bar 1, the transverse direction of which forms an angle w with the solar cell surface 30, which deviates from 90°. A light beam generated by the light source, which is indicated by an arrow, creates a shadow with a shadow width s. This shadow width s is smaller than the shadow width shown in FIG. 3a.

FIG. 3c shows a measuring bar 1 in a variant of FIG. 3b with a transverse direction that forms an angle w with the solar cell surface 30 that deviates from 90° and is smaller than the angle shown in FIG. 3b. A light beam generated by the light source, which is indicated by an arrow, creates a shadow with a shadow-casting width s. This shadow-casting width s is smaller than the shadow-casting width shown in FIGS. 3a and 3b. The more the angle w approaches 90°, the greater the shadow width s. Vice versa the arrangement shown in FIG. 3c has the smallest possible shadow width s because the transverse direction of the measuring bar 1 essentially coincides with the direction of incidence of the light beam.

4 shows a side view of a further solar cell test device according to the invention with a solar cell to be tested. The solar cell test device shown in FIG. 4 corresponds to the solar cell test device shown in FIG. 1 with the difference that the light source 2 has a number of other light modules 22 in addition to the light module 21, which are spaced apart from one another perpendicularly to the longitudinal direction. For each light-emitting module 21, 22, a light beam is shown as a dashed arrow, which, starting from the light-emitting module 21, 22, hits the left measuring bar 13. The further lighting modules 22 can be configured identically to the lighting module 21 . Because each light module 21, 22 hits the solar cell surface 30 at a different angle in the area of the left measuring bar 13, the shadow cast by one light module 21 is different than the shadow cast by another light module 22. Here the light modules 21, 22 are arranged side by side so that they form a rather square light area overall.

Fig. 5 shows a perspective view of yet another solar cell test device according to the invention with a solar cell 3 to be tested. The solar cell test device shown in Fig. 5 corresponds to the solar cell test device shown in Fig. 1 with the difference that the light source 2 has several other light modules 22 in addition to the light module 21 has, which are arranged side by side. Cameras (not shown) are positionable between them. The further lighting modules 22 can be configured identically to the lighting module 21 . Unlike in the embodiment according to FIG. 4, the light modules 21, 22 are arranged one behind the other here, that is to say spaced apart along the longitudinal direction. This creates an elongated, ideally linear, light source or luminous surface. FIG. 6 shows an arrangement in which a solar cell surface 30 is illuminated by a light source 2 with a specific width. It is intended to illustrate the purpose of an embodiment according to the invention, although no measuring bar is shown in FIG. 6 . The image plane should be arranged perpendicularly to a longitudinal direction along which a measuring bar would be oriented. Two rays of light are shown here striking the solar cell surface 30 from the outer edges of the light source where a metering bar would be located. Due to the width of the light source in the image plane, i.e. perpendicular to the longitudinal axis, there is a light ray with a smallest angle of incidence, the minimum angle of incidence w1, and a light ray with a largest angle of incidence, the maximum angle of incidence w2. If the angle w of the measuring bar arranged there is in a range between the minimum angle of incidence w1 and the maximum angle of incidence w2, then the shadow cast due to the measuring bar is reduced or minimized for some of the light rays.

In addition, it becomes clear that the shadow cast can be further reduced by means of a light source which has a smaller light source width in relation to its light source length. In this case, the values of the minimum impact angle w1 and the maximum impact angle w2 approach each other. If then the angle w of the measuring bar is selected accordingly, then a larger proportion of the light rays shown in FIG. 6 hit an optimized angle w for a minimized shadow cast.

List of reference symbols: d Strip thickness

L Longitudinal l Bar length Q Transverse direction of the measuring bar

Q2, Q3 each in the transverse direction of the other measuring bar q bar height s shadow width w angle w1 minimum angle of incidence w2 maximum angle of incidence

1 measuring bar

12, 13 each additional measuring bar

2 light source 21 light module

3 solar cell 30 solar cell surface 32 finger electrode

Claims

Patent Claims:

1 . Contacting device for making electrical contact with a solar cell (3) when measuring electrical characteristics of the solar cell (3) which has a solar cell surface (30), the contacting device having at least one measuring strip (1) which has at least one contact connection for making electrical contact with a solar cell test device and is designed to electrically contact the solar cell when the measuring bar (1) is placed on the solar cell surface (30), the measuring bar (1) extending in a longitudinal direction (L) running along the solar cell surface (30) over a bar length (l), which extends perpendicular to the longitudinal direction (L) away from the solar cell surface (30) in a transverse direction (Q) over a bar height (q) and perpendicular to the longitudinal direction (L) and the transverse direction (Q) a bar thickness (d) smaller as the strip length (l) and the strip width (q), characterized in that the transverse direction g (Q) forms an angle (w) with the solar cell surface (30) which deviates from 90°.

2. Contacting device according to claim 1, characterized in that the measuring bar (1) has a bar thickness (d) in the range of 0.2 to 5 mm, or 0.5 to 4 mm, or 1 to 3 mm.

3. Contacting device according to claim 1 or 2, characterized in that the measuring strip (1) is formed from sheet metal.

4. Contacting device according to one of the preceding claims, characterized in that the angle (w) between the transverse direction (Q) and the solar cell surface (30) is in a range between 81° and 88° or between 83° and 86°.

5. Contacting device according to one of the preceding claims, characterized in that the angle (w) between the transverse direction (Q) and the solar cell surface (30) varies along the longitudinal direction (L).

6. Contacting device according to Claim 5, characterized in that the angle (w) between the transverse direction (Q) and the solar cell surface (30) changes along the longitudinal direction (L) from a central area of the measuring bar (1) to an edge area of the measuring bar (1 ) reduced.

7. Contacting device according to one of the preceding claims, characterized by one or more additional measuring bar(s) (12; 13), the measuring bar (1) and the additional measuring bar(s) (12; 13) extending in the longitudinal direction (L). , are spaced apart from one another along the solar cell surface (30) and each extend perpendicular to the longitudinal direction (L) away from the solar cell surface in a transverse direction (Q, Q2; Q3) assigned to the respective measuring bar (1, 12; 13), with the Cross the transverse directions (Q, Q2; Q3) of the measuring strips (1, 12; 13).

8. Solar cell test device for measuring electrical characteristics of a solar cell (3), with a contacting device according to one of the preceding claims and a light source (2), which is designed to illuminate the solar cell surface (30) during the measurement of the electrical characteristics.

9. Solar cell test device according to claim 8, characterized in that the angle (w) is in a range between a minimum angle of incidence (w1) and a maximum angle of incidence (w2), which is at the position of the measuring strip (12) between the light source (2). Light beams and the solar cell surface (30) are formed in the illumination of the solar cell surface (30).

10. Solar cell test device according to claim 6 or 7, characterized in that the light source (2) extends in the longitudinal direction (L) over a light source length which is greater than one Light source width over which the light source (2) extends in a width direction perpendicular to the longitudinal direction and parallel to the solar cell surface (30).

11. Solar cell test device according to claim 10, characterized in that the light source length is at least 1.5 times, 2 times, 3 times, 4 times, 5 times, 10 times, 50 times, 100 times, 200 times times or 400 times as large as the light source width.

12. Solar cell test device according to one of claims 8 to 11, characterized in that the light source (2) is composed of a plurality of light-emitting modules (21).

13. Light source (2) for a solar cell test device for measuring electrical characteristics of a solar cell, with at least one light-emitting module (21), which has:

- Several light-generating units, each of the light-generating units having at least one illuminant with a downstream, light-bundling primary optics;

- A light-homogenizing secondary optics downstream of the light-generating units;

- an imaging tertiary optics downstream of the secondary optics, with the illuminant generating light in a plurality of separately controllable wavelength ranges, characterized in that the secondary optics and/or the tertiary optics fill out a luminous surface which extends along a first direction over a light source length and along a second direction perpendicular thereto Direction extends over a light source width, wherein the light source length is at least 1.5 times, 2 times, 3 times, 4 times or 5 times as large as the light source width.

14. Light source (2) according to claim 13, characterized in that the light source length is at least 10 times, 50 times, 100 times, 200 times or 400 times as large as the light source width.

15. Light source (2) according to claim 13 or 14, characterized by at least one further light-emitting module (21), wherein the light-emitting module (21) and the further light-emitting module (21) are arranged next to one another along the length of the light source.

16. Light source (2) according to claim 15, characterized in that the lighting module (21) and the further lighting module (22) are designed and/or arranged in such a way that the light they emit is parallel to and spaced from the Luminous plane essentially completely overlapped.

17. Light source (2) according to claim 15 or 16, characterized in that the luminous module (21) has a luminous surface and the further luminous module (22) has a further luminous surface, with a perpendicular perpendicular to the luminous surface and a further perpendicular perpendicular to the further luminous surface intersect.