Solar cell test rail

Abstract

Provision of improved test rails for testing busbarless solar cells. [Solution] The present invention provides a test rail (10) having an elongated lamellar base body (2) on which a plurality of contact elements (3) are arranged on one surface and formed integrally with the base body (2), each of the contact elements (3) having a line contact portion (4) arranged at its end and extending a predetermined length (L1) parallel to the longitudinal extension direction (L) of the base body (2), and each of the contact elements (3) having a spring element (5) arranged between the base body (2) and the contact portion (4), extending in a serpentine pattern between the base body (2) and the contact portion (4) perpendicular to the longitudinal extension direction (L) of the base body (2), and lying on a plane with the base body (2), wherein the widthwise extension amount (B) of the spring element (5) parallel to the longitudinal extension direction (L) of the base body (2) is greater than the length (L1) of each of the contact portions (4).

Description

[Technical field]

[0001] The present invention relates to a test rail and associated test apparatus for testing "busbarless" or "busbarless solar cells", in particular for releasably contacting finger electrodes of the solar cells. [Background technology]

[0002] Devices for detachable electrical contacting of solar cells for testing purposes and suitably designed measuring or test elements are known from the prior art. In particular, it is known to electrically contact the busbars of the solar cell by applying pressure, which are arranged on the solar cell. The solar cell can be checked, i.e. qualitatively evaluated, by simultaneous current and voltage measurements and irradiation with light by a testing device with one or more measuring and testing elements. Modern solar cells have a busbar-less structure, in which only finger electrodes arranged in parallel on the solar cell, the so-called "cell fingers", are present. Such solar cells can be test tapped (Pruefabgriff) simply by increasing the cell density and arranging the aforementioned finger electrodes in parallel at a given distance.

[0003] Patent document 1 describes a method and device for temporarily electrically contacting a solar cell for testing purposes, in which the test probe comprises a plurality of pointed contact elements arranged in a comb-like manner on a rail for scratching the busbar of the solar cell. A protrusion with a centrally located contact element on the outer plane of the rail is intended to provide a spring effect. However, the finger electrodes of busbarless solar cells cannot be safely contacted due to the specific design of the test rail. Also, the design of the protrusions may cause parts of the solar cell to be shaded during testing, compromising the test results.

[0004] Patent document 2 describes an integrated test rail for electrically contacting the busbars of solar cells, which includes a plurality of pointed contact fingers extending substantially perpendicular to the longitudinal direction of the test rail. Bending elements extending laterally from the linear extension of the contact fingers in the longitudinal direction of the test rail are intended to provide a spring effect in the longitudinal direction of the contact fingers. Furthermore, this design is not suitable for safely contacting the cell fingers of busbarless solar cells.

[0005] US Patent No. 5,399,633 describes a test rail for busbarless solar cells, comprising a thin-walled body, a number of contact elements connected thereto, and a spring element disposed therebetween. The spring elements each have two wire elements arranged on either side of the respective contact element, running parallel at an angle perpendicular to the plane of the body, and angled with respect to each other. However, this design of the spring elements results in undesirable tilting of the contacts when contacting the finger electrodes, compromising the contact quality during the test process. Furthermore, the out-of-plane positioning of the angled spring elements with respect to the body would result in undesirable increased shading during the test process.

[0006] Patent Document 4 describes a busbarless solar cell test rail that includes a rail-shaped body and a number of loop-shaped or hook-shaped contact springs extending therefrom. The hook-shaped design encourages the contact parts of the solar cell to be tested to tilt unexpectedly. The loop-shaped design is a major constraint due to the stroke required for testing the solar cell and the tendency of adjacent contact parts to come into contact along the length of the rail. In particular, the loop-shaped design causes the contact parts to tilt or bend significantly, impairing the contact quality and test accuracy. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] DE 10 2008 038 184 A1 [Patent Document 2] WO 2012 / 095275 [Patent Document 3] DE10 2018 132 451A1 [Patent Document 4] WO2019 / 154464A1 Summary of the Invention [Problem to be solved by the invention]

[0008] Based on the known prior art, it is an object of the present invention to provide an improved test element for testing solar cells, in particular for testing busbar-less solar cells, which addresses the aforementioned drawbacks of the prior art, in particular by allowing a simple construction design and reliable contact for many test cycles in addition to a high contact quality and high test quality. [Means for solving the problem]

[0009] This problem is solved by a test rail and a testing device according to the independent claims. Advantageous further embodiments of the invention are described in the dependent claims.

[0010] In a first aspect, the invention relates to a test rail for detachable electrical contacting of conductive substrates, in particular busbar-less solar cells, characterized in that it comprises an elongated lamellar-shaped base body and a number of contact elements arranged on one side thereof and integrally formed with the substrate, each of the contact elements having a linear contact portion arranged on its tip side and extending a given length parallel to the longitudinal extension of the base body, and in each case having a spring element arranged between the base body and the contact portion, extending in a meandering manner essentially perpendicular to the longitudinal extension of the base body between the base body and the contact portion and lying in a plane with the base body such that the width extension of the spring element parallel to the longitudinal extension of the base body is greater than the length of the respective contact portion.

[0011] The design of the test rail according to the invention, in combination with the design of the linear contacts and the spring elements according to the invention, makes it possible to improve the contact quality when contacting the finger electrodes of the solar cell being tested under the application of relatively low forces during the test procedure. Due to the selection of a width of the serpentine spring elements that is greater than the length of the contacts, on the one hand an effective spring effect is obtained for many test cycles and at the same time a stable alignment of the contacts is achieved even in the compressed state of the contact elements. In this case, a tendency of tilting and / or displacement of the respective contacts when contacting the finger electrodes is avoided, in particular in comparison with the angled spring elements according to the prior art. Furthermore, the design according to the invention allows a relatively high stroke of the contact elements and a close juxtaposition of adjacent contacts in the longitudinal direction, whereby a reliable contact of the finger electrodes of the solar cell is achieved. Due to the respective contacts being arranged parallel to the longitudinal direction of the base body and the spring elements being arranged flush with the base body, shadows during the test procedure can be minimized and a high test quality can be achieved.

[0012] The term "meandering" is understood to mean a plurality of alternatingly bent courses of spring elements in a direction essentially perpendicular to the longitudinal extension of the main body or contact element, which have a predetermined width of extension, i.e. perpendicular to the basic extension of the spring elements. The spring elements preferably do not have straight sections that are arranged perpendicular to the longitudinal extension of the main body. The spring elements also preferably do not have straight sections that are angled with respect to one another.

[0013] The term "lying in a plane" is understood to mean that the spring elements extend or are arranged completely in a plane in which the lamella base body also extends or is arranged. This is defined by the longitudinal extension of the basic body and a direction perpendicular thereto, in particular the extension in the height direction of the basic body. Thus, the spring elements run parallel to the lamella base body. The contacts are preferably also in the plane with the base body.

[0014] Each contact is preferably lamellar and has a linear contact surface facing away from the substrate for contacting the electrically conductive substrate, particularly preferably for contacting at least two, preferably up to three, parallel finger electrodes of the solar cell which are arranged perpendicular to the contact, with particular preference being given to designing the contact surface for contacting two or three parallel finger electrodes of the solar cell.

[0015] The line contact preferably extends from the end bend of the spring element over a certain length parallel to the longitudinal extension of the main body and exceeds the longitudinal cross-sectional or width extension of the end bend of the main body, i.e., the line contact is thus not formed, for example, as a simple flattening of the end bend of the spring element, but extends therefrom, in particular beyond the cross-sectional and / or width of the end bend as a separate contact, parallel to the longitudinal extension of the main body.

[0016] The linear contact surface preferably extends between two ends of each contact portion which are formed at right angles to the contact surface.

[0017] The spring element preferably extends from a first end of the contact portion formed perpendicular to the contact surface of the contact portion, and from a side or back surface of the contact portion facing away from the contact surface.

[0018] The spring element is preferably designed in such a way that the lines of force perpendicular to the longitudinal extension of the contact, resulting from contact with the substrate surface or the surface of the parallel finger electrodes, essentially intersect the contact at a distal second end of the contact or are stationary relative to the contact. In this case, the spring element is preferably designed in such a way that the lines of force of the spring element are applied to or intersect said distal second end of the contact during compression. This makes it possible to essentially prevent torques from being generated on the contact and to optimize the alignment of the contact when it is brought into contact with the finger electrodes.

[0019] In a preferred embodiment, the spring element extends, in side view, over its width on at least one, and preferably both, surface boundaries of an imaginary rectangular projection plane between the respective linear contact portion and the base body arranged parallel thereto, i.e. in a direction perpendicular to the longitudinal extension of the base body.

[0020] The length of the abutting portion is preferably 30 to 65%, more preferably 35 to 65%, and even more preferably 40 to 50% of the extension line of the width direction of the spring element in the longitudinal direction of the base body. The meandering configuration of the spring element is preferably composed of first and second portions bent or curved in the same direction and an intermediate third portion or a bent third portion bent or curved in the opposite direction. In a preferred embodiment, the spring element is formed from the three curved portions described above.

[0021] The spring element may have a first and a second curved portion, bent in the same direction and preferably having the same first bending radius, and a third curved portion, having a second bending radius or intermediate therebetween. The second bending radius may be larger or smaller than the first bending radius. The first bending radius is preferably 1.3-2.5 mm, more preferably 1.5-2 mm. The second bending radius is preferably 2 mm to 3 mm, more preferably 2.2 mm to 2.6 mm. In the opposite case, i.e. when the second bending radius is smaller than the first bending radius, the first bending radius is preferably 2-3 mm, more preferably 2.2-2.6 mm, and the second bending radius is preferably 1.3-2.5 mm, more preferably 1.5-2 mm.

[0022] The first and second curved sections are preferably substantially quarter-circular sections, and the intermediate third curved section is preferably semi-circular.

[0023] The first and second bends are preferably located substantially between a first end of the contact portion and the opposing base. The third bend is preferably located substantially between a second distal end of the contact portion and the opposing base. The bends of the spring element preferably run in alternating directions between the base and the contact portion.

[0024] The spring element preferably has a straight portion between the first and / or second curved portion and the third curved portion, the straight portion extending substantially parallel to the longitudinal direction of the contact portion or the base body. The straight portion preferably has a length that is 20 to 30%, more preferably 22 to 28%, of the length L1 of each contact portion. The length of the linear portion is preferably 0.3 to 1.2 mm, more preferably 0.5 to 0.9 mm.

[0025] The spring elements are preferably designed to have a stroke in a direction perpendicular to the longitudinal extension of the main body of 0.8 mm to 2.0 mm, preferably 1 to 1.5 mm. The spring elements are preferably designed to be compressed by 10 to 20%, more preferably 10 to 15%, of their height during said stroke. Each spring element preferably has a spring force of less than 0.4 N, more preferably less than 0.2 N. This allows for more effective and particularly gentle contact with the solar cell under test than ever before.

[0026] The spring elements are preferably designed to tolerate over one million load changes without significant change in shape and / or suspension characteristics.

[0027] The spring element is preferably designed to allow the stroke without changing, and in particular without increasing, the width of the spring element, i.e. the spring element is preferably designed such that in the compressed state its width does not increase compared to the uncompressed state.

[0028] In a preferred embodiment, the spring elements of each contact element of the test rail are arranged such that spring elements arranged adjacent to one another in the longitudinal extension direction are partially intermeshed, the spring elements being preferably arranged in the same manner on the test rail with respect to the serpentine course.

[0029] Preferably, the spring elements can also be arranged in such a way that no contact occurs between adjacent spring elements during the intended stroke in the direction perpendicular to the longitudinal extension of the basic body. In this case, the respective bends of adjacent spring elements can at least partially engage with each other without contacting each other in the side view of the test note. However, the respective bends of adjacent spring elements can at least partially engage with each other without contacting each other both in the unloaded and in the loaded state, i.e. when in contact with the solar cell.

[0030] The spring elements and / or the contact portions are preferably laminar and / or preferably have a uniform width. The spring elements and / or the contact portions preferably have a substantially rectangular cross section.

[0031] The length of the contact is preferably designed to be able to contact at least two, preferably up to three, conductive substrates, in particular the finger electrodes of a solar cell, preferably extending perpendicular to the contact.

[0032] Each contact portion of the contact element has a length (L1) of preferably 2.5 to 3 mm, more preferably 2.7 to 2.9 mm, and is preferably arranged such that the distance between adjacent contact portions in the longitudinal direction is 0.4 mm or less, more preferably 0.2 mm or less.

[0033] Each contact element extends from the base body over a distance or height, measured perpendicular to the longitudinal extension of the base body, of between 6 and 20 mm, more preferably between 8 and 15 mm.

[0034] The test rail preferably has a homogeneous or uniform thickness of 0.1 to 0.25 mm, more preferably 0.12 to 0.18 mm. The spring elements and each contact element constituting the contact portion preferably have a uniform thickness with the rest of the test rail.

[0035] The test rail is preferably one-piece, i.e. formed in one piece. The test rail is made of an electrically conductive material, in particular a metal. The test rail is preferably formed from a metal sheet, whereby the base body and the contact elements are pressed or machined from a homogeneous part, preferably in a single process step. In a particularly preferred embodiment, the test rail is made of copper-beryllium (CuBe2) or a copper-beryllium alloy.

[0036] The test rail may optionally be coated or plated with a conductive material. For example, the coating may consist of a gold alloy, a silver alloy, a nickel alloy, etc. Preferably, it is applied using an electroplating manufacturing process. Particularly preferably, the test rail is electroplated with a gold alloy. The coating may be applied to the entire test rail or to a portion of it, in particular only to the contact elements. In an alternative embodiment, the test rail may be made of a non-conductive material, in particular a plastic material, and is at least partially, preferably completely, coated with a conductive material. The coating may be formed by a conductive paint or a cooled liquid metal applied to the non-conductive material.

[0037] The contact elements of the test rail are preferably arranged equidistant from one another in the longitudinal direction on the base, in particular the contacts are aligned such that the mid-distance between adjacent contacts is constant.

[0038] The test rail preferably has connection means arranged on both longitudinal sides for electrical contact of the test rail, e.g. openings or holes provided in the test rail which can be used for electrical contact with correspondingly shaped connection elements.

[0039] The test rail preferably has attachment means arranged on both sides in the longitudinal direction, for example attachment holes arranged on both ends, for connection to a test device.

[0040] In a further aspect, the invention relates to a test element comprising at least two test rails according to the invention as described above, which are arranged next to each other in the transverse direction, i.e. in the thickness extension direction of the base body perpendicular to the longitudinal extension direction. In this case, the test rails are arranged in particular such that the meander-shaped formations of the spring elements of the respective test rails are arranged in opposite or the same longitudinal extension direction or longitudinal orientation. Test rails with opposite or equal longitudinal extension directions or longitudinal orientations are further preferably arranged in such a way that the distance between two contacts of a first test rail arranged adjacently in the longitudinal direction is covered by a contact of a second test rail arranged opposite or equal in side view, i.e. perpendicular to the longitudinal extension direction. This allows the contact parts of adjacent test rails to overlap, optimizing the contact to the conductive substrate, in particular to the finger electrodes of the solar cell.

[0041] In a further embodiment, the test element may further comprise a third test rail as described above and an insulating strip or rail arranged laterally intermediate the adjacent first and second test rails. The insulating rail preferably has substantially the same outer shape as the test rails. The first and second test rails can be used, for example, for current measurement or for measuring the current intensity during the test process, and the third test rail can be used for voltage measurement.

[0042] The insulating rail is preferably made of a composite material of epoxy resin and woven glass fiber (FR4) and has a substantially uniform thickness of preferably 0.1 to 0.3 mm, more preferably 0.15 to 0.25 mm.

[0043] In a further preferred embodiment, the test element has, in addition to the first and second test rails, at least one third test rail and two insulating strips or insulating rails, the first test rail being sandwiched between the two insulating rails and the second and third test rails being arranged outside the respective insulating rails. The three test rails form a symmetrical layer structure of the test element. Furthermore, outside the respective second and third test rails, a fourth and a fifth test rail can be arranged with spring elements arranged in the opposite or same direction, preferably directly adjacent to the respective second and third test rails. Test rails arranged directly adjacent to each other, i.e. test rails without intermediate insulating rails, are preferably arranged in such a way that the distance between two contacts of a first adjacent test rail arranged adjacent to each other in the longitudinal direction is covered by the contacts of a second adjacent test rail arranged in the opposite or same direction.

[0044] The respective outer test rails of the test element, i.e. the second and third test rails, optionally together with the respective adjacent fourth and fifth test rails, can for example be used for current measurements or for measuring the current intensity during the test process, while the centrally located first test rail can be used for voltage measurements. A test element designed in this way allows particularly optimal current-voltage measurements and, in particular, the uniform or symmetrical arrangement of the respective test rails makes it possible to minimize the formation of capacitances.

[0045] Instead of providing insulating strips or rails, an insulating surface or coating can be provided on one or both sides of each test rail. This can be partially or completely insulated on one or both sides, for example by a partial or full surface coating or lacquering.

[0046] In a preferred embodiment, the test element is provided with two outer protective elements, in particular thin-walled protective plates, which are preferably designed to frame the test rail arranged between them, such that only the contact parts of the respective test rails protrude in a side view of the test element. The respective spring elements preferably protrude only partially laterally. In this way, the remaining part of the test rail is covered by the protective elements.

[0047] The protective element is preferably made of metal or metal plate, for example stainless steel, and has a surface designed to minimize or suppress reflections. In particular, the protective element has a dull, i.e. non-shiny, and / or dark-colored, in particular black, surface. In this way, adverse effects on the test quality can be minimized. The thickness of the protective member is preferably 0.02-0.07 mm, more preferably 0.04-0.06 mm.

[0048] As an alternative to the aforementioned protective elements, the respective outer test rails of the test elements can be provided with a matte and / or dark coating for minimizing or suppressing reflections, which is preferably designed and arranged to cover, preferably completely, the respective outer side of the base body of the test rail.

[0049] In another aspect, the present invention relates to a test device comprising a plurality of test elements arranged parallel to one another as described above. The test device has a preferably rectangular support frame, which is designed to selectively receive and fix the test elements or test rails according to the invention, where the support frame preferably consists of coupling elements arranged opposite one another for fixing the respective test elements or test rails. The device can also have integrated or separately attachable electrical connection means for electrically contacting the individual test elements or test rails.

[0050] The carrier frame is preferably designed so that the respective test elements or test rails run parallel to one another and can, for example, be accommodated in a test device or can be contacted simultaneously with the parallel finger electrodes of the solar cells to be tested by pivoting or folding the carrier frame over the solar cells which are placed in a position defined for this purpose.

[0051] In a further aspect, the present invention relates to the use of the above-mentioned "test rail, test element or test device" for checking busbar-less solar cells, in particular for measuring the current intensity and / or the current-voltage by electrical contact of finger electrodes arranged parallel to the surface of the solar cell, preferably by simultaneous light impingement on the solar cell. In particular, this test rail can be used for efficiency measurements of busbar-less solar cells.

[0052] Further advantageous effects and details of the invention will now be explained with reference to the purely schematic and merely exemplary drawings in which: FIG. [Brief description of the drawings]

[0053] [Figure 1] FIG. 1 is a side view of a preferred embodiment of a test rail according to the present invention; [Diagram 2] FIG. 4 is a detailed view of a spring element of the test rail according to the invention. [Diagram 3] FIG. 2 is a detailed view of a contact element of a test rail according to the invention. [Figure 4a] 4A and 4B show the unsprung and sprung states of adjacent contact elements of a test rail according to the invention; [Figure 4b] 4A and 4B show the unsprung and sprung states of adjacent contact elements of a test rail according to the invention; [Diagram 5] FIG. 2 is a perspective side view of a preferred embodiment of a test element according to the invention consisting of two test rails according to the invention having different longitudinal orientations. [Figure 6]FIG. 6 is a detailed side view of the laterally overlapping contact elements of the test element according to the present invention shown in FIG. 5. [Figure 7a] FIG. 2 is a perspective side view of a further preferred embodiment of a test element according to the invention, which consists of a number of test rails and side protection elements. [Figure 7b] FIG. 2 shows a top view of a further preferred embodiment of a test element according to the invention, which consists of a number of test rails and side protection elements. [Figure 7c] FIG. 2 is an exploded view of a further preferred embodiment of a test element according to the invention, which consists of a number of test rails and side protection elements. [Figure 8a] FIG. 2 shows an exploded view of a further preferred embodiment of a test element according to the invention consisting of multiple test rails without protective elements. [Figure 8b] FIG. 2 shows an exploded view of a further preferred embodiment of a test element according to the invention with a symmetrical arrangement of the test rails; [Figure 9a] FIG. 2 shows an exploded view of a further preferred embodiment of a test element according to the invention, which consists of several test rails with their respective spring elements arranged in the same direction; [Figure 9b] FIG. 2 is a side view of a further preferred embodiment of a test element according to the invention, which consists of a number of test rails with respective spring elements arranged in the same direction; [Figure 9c] FIG. 2 is a detailed view of a further preferred embodiment of a test element according to the invention, which consists of several test rails with respective spring elements arranged in the same direction. [Figure 10a] FIG. 2 shows the unsprung state of adjacent contact elements of a further preferred embodiment of a test rail according to the invention. [Figure 10b] 4A-4D show the spring state of adjacent contact elements of a further preferred embodiment of a test rail according to the invention; [Figure 11] 1 is a perspective side view of a preferred embodiment of a test device according to the present invention; [Figure 12] 2 is a perspective side view of a connecting element of a test device for selectively fixing a respective test element or test rail in the test device; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] A preferred embodiment of a test rail 10 according to the invention will now be described with reference to Figures 1 to 3. The test rail 10 comprises an elongated lamellar base body 2 extending along a longitudinal direction L and a plurality of uniformly formed contact elements 3 attached thereto. The contact elements 3 extend essentially perpendicular to the longitudinal direction L, in particular to the height direction H, of the test rail 10 . The contact elements 3 here are preferably arranged at a constant distance from one another in the longitudinal direction of the base body 2 .

[0055] The substrate 2 preferably has a uniform thickness t. The substrate 2 may also have a uniform height. The substrate preferably has at its two ends projections 6 arranged on both sides, which serve for electrical contact of the test rails 10. These consist of electrical connection means 6a, e.g. respective openings or holes for electrical contact by corresponding connection elements.

[0056] The base body 2 further preferably has mounting means 7 arranged on both sides in the longitudinal direction, for example mounting holes or mounting bores arranged at each end, for connection to an inspection device 30.

[0057] Furthermore, the base body 2 may have a number of further bores 8, preferably centrally located and preferably of uniform size, which may provide a weight saving. In addition, a galvanic application process may take place. In particular, it is possible to optimize the process for the coating of test rails. Material savings are thereby achieved, particularly due to the surface reduction.

[0058] Each contact element 3 has a linear contact portion 4 at its tip, which extends a predetermined length L1 parallel to the longitudinal extension direction L of the base body 2, and is capable of pressing and contacting at least two, and preferably up to three, parallel finger electrodes 11 of the solar cell S under test. In the testing process, the finger electrodes 11 are preferably brought into contact in a direction perpendicular to the parallel arrangement of the finger electrodes (see FIG. 3). The individual contact portions 4 are arranged such that the distance a between adjacent contact portions 4 in the longitudinal direction L is less than 0.4 mm, and preferably less than 0.2 mm. Each contact portion 4 preferably has a uniform thickness b. The thickness b is preferably 0.1 to 0.2 mm, and more preferably 0.13 to 0.18 mm.

[0059] In a preferred embodiment, the contact portion 4 and the associated spring element 5 preferably have a substantially equal thickness b. The contact portion 4 and / or the spring element 5 preferably have a substantially rectangular cross-section.

[0060] The finger electrodes 11 are in contact with each other such that the linear or planar contact surface 4c of each contact portion 4 is located on the side of the contact portion 4 that is remote from the base 2. The contact surface 4c extends between the two ends 4a, 4b of the contact portion 4 and is preferably perpendicular to the contact surface 4c.

[0061] The spring elements 5 are arranged between the base body 2 and the contact parts 4 of the contact element, extend between them in a serpentine manner and lie in the same plane with the base body 2 and the contact parts 4. The spring elements 5 here have, in a side view, i.e. in a direction perpendicular to the longitudinal extension of the test rail 10, multiple curved courses with a width extension B, which, parallel to the longitudinal extension L of the basic body 2, is greater than the length L1 of the contact parts 4 respectively assigned to the spring elements.

[0062] The extension line B of the spring element 5 in the width direction preferably extends beyond at least one, more preferably both, surface boundary lines E1, E2 of imaginary rectangular protruding surfaces E arranged between each linear contact portion 4 and the base body 2 arranged parallel thereto. The boundary lines E1, E2 of each protruding surface E are located at opposing ends 4a, 4b of the linear contact portion 4 and are aligned perpendicular to the linear course of the linear contact portion 4.

[0063] The spring element 5 extends from a first end 4a of the contact portion 4, preferably formed perpendicular to the contact surface 4c of the contact portion 4, and is arranged in a serpentine manner on the rear side of the contact surface 4c toward the base body 2 on the opposite side.

[0064] The spring element 5 comprises first and second curved portions 5a, 5b with a first, preferably equal, bending radius r1 and an intermediate third curved portion 5c with a second bending radius r2, which is preferably greater than the bending radius r1. The curved portions 5a, 5b, 5c of the spring element 5 run between the base body 2 and the contact portion 4 with alternating bending directions. In an alternative embodiment of the spring element 5 (see Figs. 10a, 10b), the first and second curved portions 5a, 5b have a bending radius r1 greater than the bending radius r2 encompassed by the third intermediate curved portion 5c.

[0065] The first and second curved portions 5a, 5b form substantially quarter-circular arcs. The third curved portion 5c forms a substantially semicircular arc. Between the first and second curved portions 5a, 5b and the third curved portion 5c, the spring element preferably has respective straight portions 5d arranged substantially parallel to the longitudinal extension direction L1 of the contact portion 4. The individual curved portions may also merge into one another without a straight portion.

[0066] As shown in Fig. 2, the spring elements 5 of adjacent contact elements 3 are arranged such that they partially engage without coming into contact with each other. In particular, in a side view of the test rail 10, the extension lines B of the width direction of adjacent contact elements 2 overlap. Here, for example, the third curved portion 5c of the spring element 5 is arranged midway between the first and second curved portions 5a, 5b of the adjacent spring element. The individual spring elements 5 preferably have a uniform width b. This is preferably the case if the width b of the associated contact portion 4 is uniform.

[0067] 4a, 4b show the unsprung, in particular non-contact, and spring, in particular contact, states of adjacent contact elements 3 of a test rail 10 according to the invention upon application of a predetermined force K in a direction perpendicular to the longitudinal extension directions L, L1. As shown there, the partially interlocking spring elements 5 are preferably designed such that they do not come into contact with each other even at the intended stroke h when a solar cell S is contacted. A change, in particular an increase, in the width extension B of the spring elements 5 preferably does not occur when the spring elements are compressed in the direction of the force K.

[0068] Each spring element 5 is preferably designed such that, in a direction perpendicular to the longitudinal extension direction L1 of the contact portion 4, the force lines F of the spring element 5 caused by contacting the solar cell intersect or rest on the contact portion 4 at its distal second end 4b.

[0069] 5 shows a perspective side view of a preferred embodiment of a test element 20 according to the invention, which consists of two test rails 10a, 10b according to the invention as described above, which are arranged next to each other in the transverse direction, i.e. in the thickness direction perpendicular to the longitudinal extension direction L of the base body 2. The test rails 10a, 10b are thereby arranged with their longitudinal extension directions or longitudinal orientations opposed to each other. The electrical connection means 6a and / or the mounting means 7 arranged on each of the test rails 10a, 10b are thereby preferably aligned flush with each other.

[0070] As shown in FIG. 6, the test rails 10a, 10b are preferably arranged relative to each other such that the meandering of the spring elements 5, 5' of the respective test rails 10a, 10b runs in opposite directions. This allows the contact parts 4, 4' of the adjacently arranged test rails 10a, 10b to overlap, optimizing the contact state of the finger electrodes 11. In particular, the test rails 10a, 10b are arranged such that the distance a between the two corresponding contact parts 4 of the first test rail 10a arranged adjacently in the longitudinal direction is covered by the contact part 4' of the second test rail 10b arranged in the opposite direction, in side view, i.e. in a direction perpendicular to the longitudinal extension direction, as shown in FIG. 6. This arrangement allows effective detection and contact of all finger electrodes of the solar cell along the longitudinal direction of the test rail or test element.

[0071] As shown in Figures 5 and 6, the two test rails 10a, 10b in side view are preferably overlapped such that the respective spring elements 5, 5', in particular the respective third curved, preferably semicircular, portions are arranged in series in the longitudinal direction to form a plurality of partially overlapping circular structures 14.

[0072] Figures 7a to 7c show a further preferred embodiment of a test element 20' according to the invention, consisting of a number of test rails 10a, 10b, 10c and lateral protection elements 13a, 13b. Figure 7a shows the connection of the individual components of the test element 20' by means of fastening means 21 provided for this purpose, which can be guided into and fastened to the respective mounting holes 7 of the test rails 10. As shown in Figure 7b, the test element 20' has a uniform thickness t1, which is preferably between 0.5 and 1 mm, more preferably between 0.6 and 0.8 mm.

[0073] FIG. 7c is an exploded perspective view of this embodiment, in which the above-mentioned first and second test rails 10a, 10b are preferably arranged directly adjacent to each other with their longitudinal extension directions or longitudinal directions opposite to each other. The test element 20' also comprises a third test rail 10c electrically isolated from the first and second rails 10a, 10b by the also provided insulating rail 12. This means that the first and second test rails 10a, 10b can be used for measuring current or current intensity during a test procedure, and the third test rail 10c can be used for measuring voltage.

[0074] The test element 20' can also have two outer protective elements, in particular thin-walled protective plates 13a, 13b, which are preferably arranged between them to assemble the test rails 10a, 10b, 10c, in particular in such a way that only the contact parts 4 and the associated spring elements 5 of the respective test rails protrude only partially in a side view of the test element 20', the remaining parts of the test rails being thus covered by the protective elements in a side view. The protective plates 13a, 13b preferably have a matt and / or dark, preferably black, surface, whereby possible adverse effects on the test quality can be further minimized.

[0075] FIG. 8a shows an exploded view of a further preferred embodiment of a test element 20″ according to the invention, which comprises a plurality of, preferably three, test rails 10a, 10b, 10c arranged similarly to the embodiment according to FIGS. 7a-c. In contrast to the embodiment according to FIGS. 7a-c, this embodiment has a coating 22 which is applied not to the protective elements 13a, 13b but to the respective outer test rails 10a, 10c and has a matte and / or dark surface. This is preferably applied at least to the respective outer surface of the substrate 2.

[0076] FIG. 8b shows a test element according to the invention with a symmetrical arrangement of test rails 10. 2 is an exploded view of a further preferred embodiment of the test element 20″′. 20"' has, in addition to the first and second test rails 10a, 10b, at least one third test rail 10c and two insulating rails 12a, 12b, where the first test rail 10a is sandwiched between the two insulating rails 12a, 12b and the second and third test rails 10b, 10c are each arranged outside the insulating rails. Optionally, further adjacent test rails 10d, 10e can be arranged on each of the outer test rails 10a, 10b, preferably without intermediate elements.

[0077] The test rails 10a-10e form a symmetrical layer structure of the test element 20'''. Directly adjacent test rails 10b, 10d and 10c, 10e respectively are preferably arranged in such a way that the distance between two contacts 4 of a first longitudinally adjacent test rail 10b, 10c is covered by a contact of a second test rail 10d, 10e arranged in the opposite or same direction.

[0078] 9a-c show exploded, side and detailed views of a further preferred embodiment of a test element according to the invention consisting of at least two test rails 10a, 10b with a parallel or co-rotating arrangement of the respective spring elements 5 and contact elements 3. FIG. 9c, the distance between the spring elements 5 and the linear extensions of the contact portions 4 is arranged so that the distance between the contact elements 3 is equal, and the contact elements 3 aligned or arranged in the same direction with respect to the meander-shaped design of the spring elements 5 and the linear extension of the contact portions 4 are arranged so that the distance a between two contact portions 4 of the first test rail 10a arranged adjacently in the longitudinal direction is covered by the contact portion 4' of the second test rail 10b arranged in the same way. In particular, each contact element 3 of the first test rail 10a is arranged offset in the longitudinal direction of the base body 2 with respect to the contact element 3' of the second test rail 10b.

[0079] Figures 10a,b show the unsprung and sprung states of adjacent contact elements 3 of a further preferred embodiment of a test rail 10 according to the invention, similar to the example embodiment according to figures 4a,b. Deviating from figures 4a,b, each contact element 3 here has first and second curved parts 5a,5b, preferably substantially identical, with a first bending radius r1 and an intermediate third curved part 5c with a second bending radius r2, which is smaller than the first bending radius.

[0080] FIG. 11 shows a preferred embodiment of an inspection device 30 according to the present invention, which includes a plurality of The test device 30 comprises a rectangular support frame 31 for selectively mounting the test elements 20 or the test rail 10, which are arranged parallel to one another in the test device 30. The device can also have electrical connection means, e.g. connecting elements of corresponding design (not shown), for electrically contacting the individual test elements 20 or test rail 10, in particular via the respective electrical connection means 6a.

[0081] The support frame 31 preferably consists of connecting elements 32 (see also FIG. 12) arranged opposite one another for easy fastening of the respective test elements 20 or test rails 10 by means of the fastening means 21 assigned to them, which can be guided through and fastened in the respective mounting holes 7 of the test rail 10. In particular, the cylindrical fastening cylinders 21a (see FIG. 7a) of the fastening means 21 arranged on both sides can cooperate with two receiving grooves 32a of the respective connecting elements 32 arranged on the side of the central insert 32b for holding purposes. The following are some aspects included in the present invention. [Embodiment 1] A method for removably electrically contacting a conductive substrate, particularly a busbarless solar cell, comprising: The device comprises an elongated lamellar base body (2) and a plurality of contact elements (3) disposed on one surface thereof and integrally formed with the base body (2); The contact elements (3) each have a linear contact portion (4) arranged at its tip, which extends parallel to the longitudinal extension direction (L) of the base body (2) with a predetermined length (L1), and are arranged in each case between the base body (2) and the contact portion (4), and are in contact with the base body (2) and A test rail (10) having a spring element (5) which meanders between the contact portions (4) and extends essentially perpendicular to the longitudinal direction (L) of the base body (2), so that the spring element (5) lies in a plane with the base body (2) and the widthwise extension length (B) of the spring element (5) parallel to the longitudinal extension direction (L) of the base body (2) is greater than the length (L1) of each of the contact portions (4). [Embodiment 2] In the test rail (10) described in embodiment 1, the contact portion (4) is lamellar-shaped and has a linear abutment surface (4c) facing away from the base body (2) for contacting the conductive substrate, and the test rail (10) extends between both ends (4a, 4b) of the contact portion (4) which are preferably formed perpendicular to the abutment surface (4c). [Aspect 3] In the test rail (10) according to aspect 1 or 2, The spring element (5) extends from a first end (4a) of the contact portion (4), which end is preferably formed perpendicular to the abutment surface (4c) of the contact portion (4) and a test rail (10) extending from a side of the contact portion (4) facing away from the abutment surface (4c). [Aspect 4] In the test rail (10) according to any one of aspects 1 to 3, The spring element (5) is configured such that a line of force (F) of the spring element (5) in a direction perpendicular to the longitudinal extension direction of the contact portion (4) when the spring element (5) contacts the solar cell intersects the contact portion (4) at a distal second end (4b) of the contact portion (4) or contacts the contact portion (4). A test rail (10) formed so as to [Aspect 5] In the test rail (10) according to any one of aspects 1 to 4, A test rail (10) in which the widthwise extension length (B) of the spring element (5) extends over at least one, and preferably both, surface boundary lines (E1, E2) of an imaginary rectangular projection plane (E) between each of the linear contact portions (4) and the base body (2) arranged parallel thereto. [Aspect 6] In the test rail (10) according to any one of aspects 1 to 5, The test rail (10) has a spring element (5) that is made up of first and second portions (5a, 5b) curved in the same direction and an intermediate third portion (5c) curved in the opposite direction. [Aspect 7] In the test rail (10) according to aspect 6, the spring element (5) has the first and second curved portions (5a, 5b) and a third curved portion (5c) therebetween, the first and second curved portions (5a, 5b) having preferably equal first bending radii (r1); The third curved portion (5c) is greater than the first bending radius (r1) or The test rail (10) has a small second bend radius (r2). [Embodiment 8] In the test rail (10) according to embodiment 6 or 7, A test rail (10) in which the first and second curved portions (5a, 5b) are substantially quarter-circular portions and the third curved portion (5c) is substantially a semi-circular portion. [Aspect 9] In the test rail (10) according to any one of aspects 6 to 8, The spring element (5) has the first and / or second curved portions (5a, 5b) and A test rail (10) having a straight portion (5d) between the third curved portion (5c), the straight portion (5d) being arranged substantially parallel to the longitudinal extension direction (L1) of the contact portion (4). [Aspect 10] In the test rail (10) according to aspect 9, The straight portion (5d) of the test rail (10) has a length that is 20 to 30%, more preferably 22 to 28%, of the length (L1) of each contact portion. [Embodiment 11] A test rail (10) according to any one of embodiments 6 to 10, wherein the curved portions (5a, 5b, 5c) of the spring element (5) extend with alternating bending directions between the base body (2) and the contact portion (4). [Embodiment 12] In the test rail (10) according to any one of embodiments 1 to 11, The spring element (5) is designed so that the stroke (h) in a direction perpendicular to the longitudinal extension direction (L) of the base body (2) can be set to 0.8 mm to 2.0 mm, preferably 1 to 1.5 mm, without changing or particularly increasing the widthwise extension (B) of the spring element (5). [Embodiment 13] A test rail (10) according to any one of embodiments 1 to 12, wherein each of the spring elements (5) has a spring force of less than 0.4 N, more preferably less than 0.2 N. [Embodiment 14] A test rail (10) according to any one of embodiments 1 to 13, wherein the spring elements (5) of each of the contact portions (4) are arranged such that the spring elements (5) arranged adjacent to each other in the longitudinal extension direction (L) partially overlap each other. [Embodiment 15] A test rail (10) according to any one of embodiments 1 to 14, wherein the spring elements (5) are arranged such that no contact occurs between adjacent spring elements (5) for a predetermined stroke (h) in a direction perpendicular to the longitudinal extension direction (L) of the base body (2). [Embodiment 16] A test rail (10) according to any one of embodiments 1 to 15, wherein the spring element (5) and / or the contact portion (4) are lamellar in shape and have a uniform width (b). [Embodiment 17] In a test rail (10) described in any one of embodiments 1 to 16, the length (L1) of the contact portion (4) is designed so that it can contact at least two, and preferably up to three, conductive substrates, in particular finger electrodes (11), the finger electrodes (11) preferably operating perpendicular to the contact portion (4) of the solar cell (S). [Embodiment 18] A test rail (10) according to any one of embodiments 1 to 17, wherein each of the contact portions (4) has a length (L1) of 2.5 to 3 mm, preferably 2.7 to 2.9 mm, and / or the distance (a) between adjacent contact portions (4) in the longitudinal extension direction (L) is less than 0.4 mm, preferably less than 0.2 mm. [Embodiment 19] A test rail (10) according to any one of embodiments 1 to 18, wherein the contact element (3) extends from the base body (2) over a distance (d) of 6 to 20 mm, preferably 8 to 15 mm. [Embodiment 20] In a test rail (10) described in any one of embodiments 1 to 19, the test rail (10) has a preferably uniform thickness (t) of 0.1 to 0.25 mm, preferably 0.12 to 0.18 mm, and / or is formed as a single piece. [Embodiment 21] A test rail (10) described in any one of embodiments 1 to 20, wherein the contact elements (3) of each of the test rails (10) are arranged equidistant from each other in the longitudinal extension direction (L) on the base body (2). [Embodiment 22] A test element (10) having at least two test rails (10a, 10b) according to any one of embodiments 1 to 21, The test rails (10a, 10b) are arranged laterally adjacent to one another and with opposite or equal longitudinal extension directions (L), in particular such that the serpentine configurations of the spring elements (5) of each of the test rails (10a, 10b) run in opposite or equal directions and / or such that the distance (a) between two contact portions (4) of a first test rail (10a) arranged adjacent to one another in the longitudinal direction is covered by the contact portions (4') of a second test rail (10b) arranged in the opposite or equal direction. [Embodiment 23] The test element (20) according to embodiment 22, A test element (20) including at least one third test rail (10c), which is a test rail (10) described in any one of embodiments 1 to 21, and an insulating rail (12) arranged in the lateral middle of adjacent first and second test rails (10a, 10b). [Embodiment 24] The test element (20) according to embodiment 22, further comprising at least one third test rail (10c) which is the test rail (10) according to any one of embodiments 1 to 21, and two insulating rails (12a, 12b); A test element (20) arranged such that the first test rail (10a) is sandwiched between the two insulating rails (12a, 12b) and the second and third test rails (10b, 10c) are each positioned outside the insulating rails (12a, 12b). [Embodiment 25] The test element (20) according to any one of embodiments 22 to 24, The test element has two outer protective plates (13a, 13b) with a matt and / or dark surface to minimize reflections, and / or the test rails (10a, 10b, 10c) are arranged between said protective plates such that the contact portions (4) of the test rails (10a, 10b, 10c) protrude completely when viewed from the side of the test element (20) and each of the spring elements (5) protrudes at least partially from the test element (20). [Embodiment 26] A test element (20) according to any one of embodiments 22 to 24, wherein each outer test rail of the test element has a matte and / or dark coating (22) to minimize reflections, which is preferably arranged to completely cover each outer side of the base body (2) of the test rail of the test element (20). [Embodiment 27] An inspection device (30) comprising a plurality of test elements (20) arranged parallel to one another as described in any one of embodiments 22 to 26, and a preferably rectangular support frame (31) for selectively mounting the test elements (20). [Embodiment 28] Use of a test rail (10) described in any one of embodiments 1 to 21, a test element (20) described in any one of embodiments 22 to 26 or an inspection device (30) described in embodiment 27 for testing a busbarless solar cell (S), in particular for measuring current intensity and / or current voltage, by electrical contact of finger electrodes (11) arranged on the surface of the solar cell, preferably by simultaneous irradiation of the solar cell with light.

Claims

1. A test rail (10) for removably electrically contacting a conductive substrate, comprising: The device comprises an elongated lamellar base body (2) and, on one side thereof, a number of contact elements (3) integrally formed with said base body (2), Each of the contact elements (3) comprises a linear contact portion (4) disposed at a tip thereof, extending for a predetermined length (L1) parallel to the longitudinal extension direction (L) of the base body (2), and a spring element (5) disposed between the base body (2) and the contact portion (4); The spring element (5) extends perpendicular to the longitudinal direction (L) of the base body (2) in a serpentine manner between the base body (2) and the end surface of the contact portion (4), A test rail (10) in which the extension length (B) of the spring element (5) is parallel to the longitudinal direction (L) of the base body (2) and is greater than the length (L1) of each of the contact portions (4).

2. A test rail (10) according to claim 1, The contact portion (4) is lamellar in shape and has a linear abutment surface (4c) facing away from the base body (2) for contacting the conductive substrate, the abutment surface (4c) being a test rail (10) extending between both ends (4a, 4b) of the contact portion (4).

3. A test rail (10) according to claim 1 or 2, The spring element (5) extends from a first end (4a) of the contact portion (4), which end is formed at a right angle to the abutment surface (4c) of the contact portion (4) and extends from a side of the contact portion (4) facing away from the abutment surface (4c).

4. A test rail (10) according to any one of claims 1 to 3, The spring element (5) is formed in such a way that a line of force (F) of the spring element (5) in a direction perpendicular to the longitudinal extension direction of the contact portion (4) that arises when the spring element (5) contacts a busbarless solar cell intersects with or contacts the contact portion (4) at a distal second end (4b) of the contact portion (4).

5. A test rail (10) according to any one of claims 1 to 4, A test rail (10) in which the widthwise extension length (B) of the spring element (5) extends over at least one surface boundary line (E1, E2) of an imaginary rectangular projection plane (E) between each of the linear contact portions (4) and the base body (2) arranged parallel thereto.

6. A test rail (10) according to any one of claims 1 to 5, The test rail (10) comprises a spring element (5) having first and second portions (5a, 5b) curved in the same direction and an intermediate third portion (5c) curved in the opposite direction.

7. A test rail (10) according to claim 6, the spring element (5) having the first and second curved portions (5a, 5b) with equal first bending radii and a third curved portion (5c) therebetween; The third curved portion (5c) has a second bending radius (r2) which is greater than or less than the first bending radius (r1).

8. A test rail (10) according to claim 6 or 7, A test rail (10) in which the first and second curved portions (5a, 5b) are substantially quarter-circular portions and the third curved portion (5c) is substantially a semi-circular portion.

9. A test rail (10) according to any one of claims 6 to 8, The spring element (5) has a straight portion (5d) between the first and / or second curved portions (5a, 5b) and the third curved portion (5c), the straight portion (5d) being arranged substantially parallel to the longitudinal extension direction (L1) of the contact portion (4).

10. A test rail (10) according to claim 9, The straight portion (5d) has a length which is 20-30% of the length (L1) of each contact portion of the test rail (10).

11. A test rail (10) according to any one of claims 6 to 10, A test rail (10) in which the curved portions (5a, 5b, 5c) of the spring element (5) extend between the base body (2) and the contact portion (4) with alternating bending directions.

12. A test rail (10) according to any one of claims 1 to 11, The spring element (5) is designed so that the widthwise extension (B) of the spring element (5) is not changed and the stroke (h) in a direction perpendicular to the longitudinal extension direction (L) of the base body (2) can be set to 0.8 mm to 2.0 mm.

13. A test rail (10) according to any one of claims 1 to 12, A test rail (10) in which each of said spring elements (5) has a spring force of less than 0.4N.

14. A test rail (10) according to any one of claims 1 to 13, A test rail (10) in which the spring elements (5) of each of the contact portions (4) are arranged such that the spring elements (5) arranged adjacent to each other in the longitudinal extension direction (L) partially overlap each other.

15. A test rail (10) according to any one of claims 1 to 14, A test rail (10) in which the spring elements (5) are arranged such that no contact occurs between adjacent spring elements (5) for a given stroke (h) in a direction perpendicular to the longitudinal extension direction (L) of the base body (2).

16. A test rail (10) according to any one of claims 1 to 15, A test rail (10) in which the spring elements (5) and / or the contact portions (4) are lamellar and have a uniform width (b).

17. A test rail (10) according to any one of claims 1 to 16, The length (L1) of the contact portion (4) is designed to be able to contact at least two conductive substrates, and the finger electrodes (11) act perpendicular to the contact portion (4) as a test rail (10).

18. A test rail (10) according to any one of claims 1 to 17, A test rail (10) in which each of the contact portions (4) has a length (L1) of 2.5 to 3 mm and / or the distance (a) between adjacent contact portions (4) in the longitudinal extension direction (L) is less than 0.4 mm.

19. A test rail (10) according to any one of the preceding claims, The contact element (3) extends from the base body (2) over a distance (d) of 6 to 20 mm.

20. A test rail (10) according to any one of the preceding claims, The test rail (10) has a uniform thickness (t) of 0.1 to 0.25 mm and / or is formed integrally.

21. A test rail (10) according to any one of claims 1 to 20, The contact elements (3) of each of the test rails (10) are arranged equidistant from one another in a longitudinal extension direction (L) on the base body (2).

22. A test element (10) having at least two test rails (10a, 10b) according to any one of the preceding claims, The test element (20) is arranged such that the test rails (10a, 10b) are arranged laterally adjacent to one another and with their longitudinal extension directions (L) opposite or equal to one another and / or such that the distance (a) between the two contact portions (4) of a first test rail (10a) arranged adjacent to one another in the longitudinal direction is covered by the contact portions (4') of a second test rail (10b) arranged in the opposite or equal direction.

23. A test element (20) according to claim 22, A test element (20) comprising at least one third test rail (10c) which is a test rail (10) according to any one of claims 1 to 21, and an insulating rail (12) arranged in the lateral middle of adjacent first and second test rails (10a, 10b).

24. A test element (20) according to claim 22, At least one third test rail (10c), which is a test rail (10) according to any one of claims 1 to 21, and two insulating rails (12a, 12b), A test element (20) arranged such that the first test rail (10a) is sandwiched between the two insulating rails (12a, 12b) and the second and third test rails (10b, 10c) are each positioned outside the insulating rails (12a, 12b).

25. A test element (20) according to any one of claims 22 to 24, The test element has two outer protective plates (13a, 13b) with a matte and / or dark surface to minimize reflections, and / or the test rail (10a, 10b, 10c) is arranged between said protective plates such that the contact portions (4) of the test rails (10a, 10b, 10c) protrude completely when viewed from the side of the test element (20) and each of the spring elements (5) protrudes at least partially from the test element (20).

26. A test element (20) according to any one of claims 22 to 24, The test element (20) has an outer test rail of each of said test elements having a matte and / or dark coating (22) to minimize reflections.

27. 27. An inspection device (30) comprising a plurality of test elements (20) arranged parallel to one another according to any one of claims 22 to 26, and a support frame (31) for selectively mounting said test elements (20).

28. Use of a test rail (10) according to any one of claims 1 to 21, a test element (20) according to any one of claims 22 to 26 or an inspection device (30) according to claim 27 for testing a busbarless solar cell (S) by electrical contact of finger electrodes (11) arranged on the solar cell surface.

29. In the test rail (10) according to claim 1, The contact portion (4) is lamella-shaped and has a linear abutment surface (4c) facing away from the base body (2) for contacting the conductive substrate, and a test rail (10) extending between both ends (4a, 4b) of the contact surface (4) formed at right angles to the abutment surface.

30. The test rail (10) according to claim 6, the spring element (5) has the first and second curved portions (5a, 5b) and a third curved portion (5c) therebetween, the first and second curved portions (5a, 5b) having an equal first bending radius (r1); The third curved portion (5c) has a second bending radius (r2) which is greater than or less than the first bending radius (r1).

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