Test busbars for solar cells

Abstract

The invention relates to a test busbar (10) for releasably electrically contacting an electrically conductive substrate, in particular a solar cell without a busbar, comprising: an elongated sheet-like base body (2), the base body (2) having a plurality of contact elements (3) arranged on one side thereof and formed integrally with the base body; wherein each contact element (3) has a linear contact section (4) arranged at the end side, the contact section (4) extending parallel to the longitudinal extension direction (L) of the base body (2) with a predefined length (L1); and spring elements (5) arranged between the base body (2) and the contact section (4), the spring elements (5) extending substantially perpendicularly to the longitudinal extension direction (L) of the base body (2) in a meandering manner between the base body (2) and the contact section (4) and in a plane with the base body (2) such that a width extension (B) of the spring elements (5) parallel to the longitudinal extension direction (L) of the base body (2) is greater than the length (L1) of the respective contact section (4).

Description

Technical Field

[0001] The invention relates to a test busbar for testing solar cells without busbars, in particular for releasably contacting finger electrodes of solar cells, and an associated test device. Background Art

[0002] Devices for releasably making electrical contact with solar cells for testing purposes and correspondingly designed measuring or test elements are known in the prior art. In particular, busbars, or so-called "busbars," arranged on the solar cell, which electrically contact the solar cell by pressing are known. By exposing the solar cell to light while performing current and / or voltage measurements using corresponding testing devices with one or more measuring or test elements, the solar cell can be inspected and thus qualitatively evaluated. Newer solar cells have a design without busbars, with only finger electrodes, or so-called "cell fingers," arranged in parallel on the solar cell. Such solar cells can offer increased cell density and have only the aforementioned finger electrodes arranged in parallel at predefined intervals for possible test taps.

[0003] DE 10 2008 038 184 A1 describes a method and a device for temporarily electrically contacting a solar cell for testing purposes. A test probe comprises a plurality of pointed contact elements arranged in a comb-like manner on the busbars of the solar cell for scraping against them. The centrally arranged protrusions of the contact elements, arranged in a plane outside the busbar, are intended to provide a spring action. However, the specific design of the test busbars does not allow reliable contact with the finger electrodes of solar cells, particularly those without busbars. Furthermore, the design of the protrusions can lead to partial shading of the solar cell during testing, which can affect the test results.

[0004] WO 2012 / 095275 describes a one-piece test busbar for electrically contacting a busbar of a solar cell. The test busbar has a plurality of tapering contact fingers extending substantially perpendicularly to the longitudinal direction of the test busbar. Bend elements extending laterally from the linear extension of the contact fingers in the longitudinal direction of the test busbar are intended to provide a spring action in the longitudinal direction of the contact fingers. However, this design is not suitable for reliably contacting the cell fingers of solar cells without a busbar.

[0005] DE 10 2018 13 2 451 A1 describes a test busbar for solar cells without busbars. The test busbar comprises a thin-walled body, a plurality of contact elements connected to the body, and a spring element positioned between the body and the plurality of contact elements. Each spring element comprises two parallel, angled wire elements, which are arranged on either side of the respective contact element and extend obliquely perpendicular to the plane of the body. However, this design of the spring elements results in an undesirable tendency for the contact sections to tilt when contacting the finger electrodes, thereby impairing the contact quality during testing. Furthermore, the arrangement of the angled spring elements in a plane outside the plane of the body leads to an increase in undesirable shadowing during testing.

[0006] WO2019 / 154464A1 describes a test busbar for solar cells without busbars, comprising a busbar-shaped body and contact spring segments extending from the body in a ring-shaped or hook-shaped configuration. The hook-shaped design described therein promotes undesirable tilting of the contact segments on the finger electrodes of the solar cell to be tested. The described ring-shaped configuration leads to significant limitations in the necessary travel when testing the solar cell and in the alignment of adjacent contact segments along the longitudinal direction of the busbar due to the contact tendency of these contact segments. In particular, the ring-shaped configuration shown leads to a significant tendency for the contact segments to tilt and bend, thereby impairing contact quality and test accuracy. Summary of the Invention

[0007] Based on the known prior art, the object of the present invention is to provide an improved test element for testing solar cells, in particular for testing solar cells without busbars, which overcomes the aforementioned disadvantages of the prior art. In particular, the test element should not only have high contact quality and high test quality but also allow for a simple design and reliable contacting for a large number of test cycles.

[0008] This object is achieved by the test busbar and the test device according to the invention. Furthermore, advantageous developments of the invention are described.

[0009] In a first aspect, the invention relates to a test busbar for releasably electrically contacting an electrically conductive substrate, in particular a solar cell without a busbar, comprising: an elongated sheet-like base body having a plurality of contact elements arranged on one side thereof and formed integrally with the base body; wherein the contact elements each have a linear contact section arranged at the end side, which extends with a predefined length parallel to the longitudinal extension direction of the base body; and spring elements respectively arranged between the base body and the contact section, which extend in a meandering manner between the base body and the contact section essentially perpendicular to the longitudinal extension direction of the base body and in a manner located in one plane with the base body, such that the width of the spring element parallel to the longitudinal extension direction of the base body extends greater than the length of the respective contact section.

[0010] The design of the test busbar according to the present invention, through the combination of linear contact segments and the design of the spring element according to the present invention, improves the contact quality when contacting the finger electrodes of the solar cell to be tested, even with relatively low forces applied during testing. The width of the meandering spring element, selected to be greater than the corresponding length of the contact segment, ensures an effective spring action for a large number of test cycles while also ensuring a stable orientation of the contact segment, even when the contact element is in the spring-loaded state. This prevents tilting and / or displacement of the contact segment during contacting the finger electrodes, particularly compared to angled spring elements of the prior art. Furthermore, the design according to the present invention allows for a relatively large stroke of the contact element and close alignment of adjacent contact segments along the longitudinal extension, thereby enabling reliable contacting of the finger electrodes of the solar cell. Furthermore, by aligning the contact segments parallel to the longitudinal extension of the base body and arranging or extending the spring element in a single plane with the base body, shadowing during testing is minimized, thereby achieving high test quality.

[0011] In the present context, the term "meandering" is to be understood as a spring element extending in a direction substantially perpendicular to the longitudinal extension of the base body or contact element, with a predefined width, i.e., an extension perpendicular to the spring element's primary extension direction. The spring element preferably has no linear sections arranged perpendicular to the longitudinal extension of the base body. Furthermore, the spring element preferably has no linear sections that are angled relative to one another.

[0012] The expression "lying in a plane with the base body" should be understood to mean that the spring element extends or is arranged completely in a plane, in which the sheet-like base body also extends or is arranged. This plane is spanned by the longitudinal extension of the base body and a direction perpendicular thereto, in particular the height extension of the base body. Thus, the spring element extends parallel to the sheet-like base body. The contact section also preferably lies in a plane with the base body.

[0013] The respective contact section is preferably plate-shaped and has a linear support surface for contacting the electrically conductive substrate facing away from the base body, in particular for contacting at least two and preferably at most three parallel-running finger electrodes of the solar cell, preferably arranged perpendicular to the contact section. Particularly preferably, the support surface is formed as two or three parallel-running finger electrodes for contacting the solar cell.

[0014] The linear contact section preferably extends by a predefined length from the end-side bent section of the spring element parallel to the longitudinal extension of the base body and beyond the cross-sectional extension or width extension of the end-side bent section parallel to the longitudinal direction of the base body. In other words, the linear contact section is therefore not designed, for example, as an exposed flat portion of the end-side bent section of the spring element, but extends therefrom, in particular beyond the cross-sectional extension and / or width of the end-side bent section, as a separate contact section and parallel to the longitudinal extension of the base body.

[0015] The linear support surface preferably extends between two ends of the respective contact section which are formed at a right angle to the support surface.

[0016] The spring element preferably extends away from a first end of the contact section, which is preferably formed at a right angle to the support surface of the contact section, and away from the side of the contact section facing away from the support surface, ie the rear side.

[0017] The spring element is preferably designed such that the force lines generated when contacting the substrate surface or the parallel-running finger electrodes intersect the contact segment substantially at the second distal end of the contact segment, perpendicular to the longitudinal extension of the contact segment. In this case, the spring element is preferably designed such that the force lines of the spring element, when spring-loaded, intersect the second distal end of the contact segment or intersect this end. This substantially prevents the occurrence of torque on the contact segment, thereby achieving optimal orientation of the contact segment when contacting the finger electrodes.

[0018] In a preferred embodiment, the spring element extends with its width at least through one, preferably two, surface boundary lines of the virtual rectangular projection surface between the corresponding linear contact section and the parallel arranged base body, i.e., in a direction perpendicular to the longitudinal extension direction of the base body when viewed in a side view.

[0019] The length of the contact section is preferably 30% to 65% of the width of the spring element along the longitudinal direction of the base body, more preferably 35% to 65%, and even more preferably 40% to 50%. The spring element's meandering structure preferably includes first and second sections that are bent or angled in the same direction, and a third or intermediate section located between the first and second sections and bent or angled in a direction opposite thereto. In a preferred embodiment, the spring element is formed from these three curved sections.

[0020] In this case, the spring element can have first and second curved sections, preferably having the same first bending radius, and a third curved section located between the first and second curved sections, wherein the first and second curved sections have a second bending radius. In this case, the second bending radius can be larger or smaller than the first bending radius. The first bending radius is preferably between 1.3 mm and 2.5 mm, more preferably between 1.5 mm and 2 mm. The second bending radius is preferably between 2 mm and 3 mm, more preferably between 2.2 mm and 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 between 2 mm and 3 mm, more preferably between 2.2 mm and 2.6 mm, and the second bending radius is preferably between 1.3 mm and 2.5 mm, more preferably between 1.5 mm and 2 mm.

[0021] The first and second curved segments are preferably substantially quarter-circle segments.The third curved segment located between the first and second curved segments is preferably a semicircular segment.

[0022] The first and second curved sections are preferably arranged substantially between the first end of the contact section and the opposing base body. The third curved section is preferably arranged substantially between the second distal end of the contact section and the opposing base body. The curved sections of the spring element preferably extend in alternating curvature directions between the base body and the contact portion.

[0023] The spring element preferably has a linear section between the first and / or second curved section and the third curved section, the linear section extending substantially parallel to the longitudinal extension of the contact section or the base body. The linear section preferably has a length that is 20% to 30%, more preferably 22% to 28%, of the length L1 of the corresponding contact section. The length of the linear section is preferably 0.3 mm to 1.2 mm, more preferably 0.5 mm to 0.9 mm.

[0024] The spring element is preferably designed such that it achieves a travel of 0.8 mm to 2.0 mm, preferably 1 mm to 1.5 mm, in a direction perpendicular to the longitudinal extension of the base body. The spring element is preferably designed such that its height is compressed by 10% to 20%, more preferably 10% to 15%, during this travel. The respective spring element preferably has a spring force of less than 0.4 N, more preferably less than 0.2 N. This allows for effective contacting of the solar cell to be tested, while also being particularly smooth compared to the prior art.

[0025] The spring element is preferably designed in such a way that it can undergo more than one million load changes without any significant change in shape and / or spring properties.

[0026] The spring element is preferably constructed so that the spring element can achieve a stroke without changing and especially increasing the width of the spring element. In other words, the spring element is preferably constructed so that its width extension or width in the spring-loaded state does not increase compared to the non-spring-loaded state.

[0027] In a preferred embodiment, the spring elements of the respective contact elements of the test busbar are arranged so that the spring elements arranged adjacent to each other in the longitudinal extension direction partially engage with each other. Here, the spring elements are preferably arranged in the same manner on the test busbar in terms of their meandering extension.

[0028] Preferably, the spring elements can also be arranged such that no contact between adjacent spring elements occurs within a predetermined travel in a direction perpendicular to the longitudinal extension of the base body. In this case, corresponding bends of adjacent spring elements can at least partially engage with one another in a side view of the test busbar without contact, neither in the unloaded state nor in the loaded state, i.e., when contacting the solar cell.

[0029] The spring element and / or the contact section are preferably designed in a lamellar manner and / or preferably have a uniform width. The spring element and / or the contact section preferably have a substantially rectangular cross section.

[0030] The length of the contact segments is preferably designed so that they can contact at least two and preferably at most three electrically conductive substrates, in particular finger electrodes, of the solar cell, which preferably extend perpendicularly to the contact segments. The respective contact segments of the contact element preferably have a length of 2.5 mm to 3 mm, more preferably 2.7 mm to 2.9 mm. The respective contact segments are preferably arranged so that the distance between adjacent contact segments along the longitudinal extension is less than 0.4 mm, more preferably less than 0.2 mm.

[0031] The respective contact element extends from the base body over a distance or height of 6 mm to 20 mm, more preferably 8 mm to 15 mm, measured perpendicularly to the longitudinal extension of the base body.

[0032] The test busbar preferably has a uniform or uniform thickness of 0.1 mm to 0.25 mm, more preferably 0.12 mm to 0.18 mm. In this case, the corresponding contact element with the spring element and the contact section preferably has a uniform thickness as the rest of the test busbar.

[0033] The test busbar is preferably integral, i.e., one-piece. It is formed from an electrically conductive material, in particular metal. It is preferably formed from sheet metal, with the base body and contact elements preferably being stamped or cut from a single component in a single processing step. In a particularly preferred embodiment, the test busbar consists of copper beryllium (CuBe2) or a copper beryllium alloy.

[0034] The test busbars can optionally be coated or finished with a conductive material. The coating can, for example, include a gold alloy, a silver alloy, a nickel alloy, or the like. The coating is preferably applied using an electroplating manufacturing method. Particularly preferably, the test busbars are electroplated with a gold alloy. The coating can be applied completely or only partially to the test busbars, in particular only to the contact elements. In an alternative embodiment, the test busbars can be formed from a non-conductive material, in particular a plastic material, and at least partially, and preferably completely, coated with a conductive material. The coating can be formed from a conductive paint or cold liquid metal applied to the non-conductive material.

[0035] The corresponding contact elements of the test busbar are preferably arranged equidistant from one another on the base body along the longitudinal extension direction. In this case, in particular, the contact sections are oriented to one another so that the distance between adjacent contact sections is constant.

[0036] The test busbar preferably has connecting means for electrical contacting the test busbar, which are arranged on both sides in the longitudinal extent of the test busbar, for example openings or holes in the test busbar, which can be used for electrical contacting with correspondingly shaped connecting elements.

[0037] The test busbar further preferably has mounting means for connection to a test device, which are arranged on both sides in the longitudinal extension direction, for example mounting openings arranged in each case on the end sides.

[0038] In another aspect, the present invention relates to a test element having at least two test busbars according to the invention as described above, wherein the test busbars are arranged side by side in a transverse direction, i.e., in a direction extending perpendicularly to the longitudinal direction of the base body. In this case, the test busbars are arranged with mutually opposite or identical longitudinal directions of extension or longitudinal orientations, in particular such that the meandering configurations of the spring elements of the respective test busbars are arranged opposite or identically to one another. The test busbars are preferably further arranged with the same or identical longitudinal directions of extension or longitudinal orientations such that the distance between two contact sections arranged adjacently in the longitudinal direction of a first test busbar is covered in a side view, i.e., perpendicularly to the longitudinal direction of extension, by the oppositely or identically arranged contact sections of a second test busbar. As a result, an overlap of the contact sections of adjacently arranged test busbars is achieved, thereby enabling optimized contacting of the conductive substrate and, in particular, the finger electrodes of a solar cell.

[0039] The test element may also include a third test busbar as described above and an insulating strip or insulating busbar, which is arranged in a transverse direction interposed between the adjacent first and second test busbars. The insulating busbar preferably has an outer contour substantially identical to that of the test busbars. The first and second test busbars can, for example, be used for current measurement or current intensity measurement during a test, and the third test busbar can be used for voltage measurement.

[0040] The insulating busbar is preferably formed from a composite material made of epoxy resin and glass fiber fabric (FR4).The insulating busbar preferably has a substantially uniform thickness of 0.1 mm to 0.3 mm, more preferably 0.15 mm to 0.25 mm.

[0041] In another preferred embodiment, the test element includes, in addition to the first and second test busbars, at least one third test busbar and two insulating strips or insulating busbars, wherein the first test busbar is arranged in a sandwich-like manner between the two insulating busbars, and the second and third test busbars are each arranged externally on an insulating busbar. In this case, the three test busbars form a symmetrical layered structure of the test element. Furthermore, a fourth and fifth test busbars having spring elements arranged opposite or in the same direction may be arranged externally on the second and third test busbars, preferably directly adjacent to the respective second and third test busbars. In this case, the respective directly adjacent test busbars, i.e., arranged without an intervening insulating busbar, are preferably arranged such that the distance between two longitudinally adjacent contact sections of a first adjacent test busbar is covered by the oppositely or identically arranged contact sections of a second adjacent test busbar.

[0042] The correspondingly positioned test busbars of the test element, namely the second and third test busbars, optionally together with the fourth and fifth test busbars arranged adjacent to them, can be used, for example, for current measurement or current intensity measurement during a test, and the centrally arranged first test busbar can be used for voltage measurement. A test element constructed in this manner enables particularly optimized current and voltage measurement and, in particular, minimized capacitance buildup due to the uniform or symmetrical arrangement of the corresponding test busbars.

[0043] As an alternative to the arrangement of insulating strips or insulating busbars, the respective test busbar can have an insulating surface or coating arranged on one or both sides. This insulating surface or coating can be designed to be partially or completely insulating on one or both sides, for example by partial or full surface coating or painting.

[0044] In a preferred embodiment, the test element has two outer protective elements, in particular thin-walled protective plates. These two protective plates are preferably designed so that they frame the test busbar, which is arranged between them, preferably in such a way that preferably only the contact section of the respective test busbar protrudes in a side view of the test element. The respective spring element preferably protrudes only partially laterally. The remaining portion of the test busbar is thus covered by the protective element.

[0045] The protective element is preferably formed from metal or metal sheet, such as stainless steel, and has a surface designed to minimize or suppress reflections. In particular, the protective element has a matte, i.e., non-shiny, and / or dark, particularly black, surface. This further minimizes any negative impact on test quality. The protective element preferably has a thickness of 0.02 mm to 0.07 mm, more preferably 0.04 mm to 0.06 mm.

[0046] As an alternative to the aforementioned protective element, the respective outer test busbars of the test element may have a matte and / or dark coating for minimizing or suppressing reflections. The coating is preferably designed or arranged such that it preferably completely covers the respective outer surface of the base body of the test busbar.

[0047] In another aspect, the present invention relates to a test device having a plurality of test elements arranged parallel to one another as described above. In this case, the test device comprises a carrier frame, preferably of rectangular design, configured for selectively receiving and securing test elements or test busbars according to the present invention. In this case, the carrier frame preferably includes correspondingly opposed connecting elements for securing the respective test elements or test busbars. The device may also have integrated or separately attachable electrical connecting means for electrically contacting the individual test elements or test busbars.

[0048] The carrier frame is preferably designed in such a way that the respective test elements or test busbars can extend parallel to one another and preferably simultaneously contact parallel finger electrodes of the solar cell to be tested, for example by pivoting or folding the carrier frame down onto the solar cell which can be accommodated in a test device or can be arranged in a defined position relative to the test device.

[0049] In another aspect, the present invention relates to the use of a test busbar, a test element, or a test device as described above for checking solar cells without busbars, in particular for current intensity and / or current-voltage measurements, by making electrical contact with finger electrodes arranged in parallel on the surface of the solar cell, preferably while simultaneously exposing the solar cell to light. In particular, the test busbar can be used for efficiency measurements of solar cells without busbars. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The details, further advantageous effects and further developments of the invention are explained below with reference to the purely schematic and merely exemplary drawings, in which:

[0051] Figure 1 A preferred embodiment of a test busbar according to the present invention is shown in a side view;

[0052] Figure 2 shows a detailed view of a spring element of a test busbar according to the invention;

[0053] Figure 3 A detailed view showing the contact elements of the test busbar of the present invention;

[0054] Figure 4a 、 Figure 4b shows a non-spring-loaded state and a spring-loaded state of adjacent contact elements of a test busbar according to the invention;

[0055] Figure 5 shows a perspective side view of a preferred embodiment of a test element according to the invention, which has two test busbars according to the invention, the two test busbars having different longitudinal orientations;

[0056] Figure 6 The side view shows the Figure 5 Detailed view of the contact elements of the test element according to the invention overlapping in the lateral direction;

[0057] Figures 7a to 7c A perspective side view, a top view and an exploded view of another preferred embodiment of a test element according to the invention are shown, which has a plurality of test busbars and a lateral protection element;

[0058] Figure 8a shows an exploded view of another preferred embodiment of a test element according to the invention, which has a plurality of test busbars without protective elements;

[0059] Figure 8b shows an exploded view of another preferred embodiment of a test element according to the invention, which has a symmetrical arrangement of the test busbars;

[0060] Figures 9a to 9c shows an exploded view, a side view and a detailed view of a further preferred embodiment of a test element according to the invention, which has a plurality of test busbars with an identically oriented arrangement of the corresponding spring elements;

[0061] Figure 10a 、 Figure 10b shows a non-spring-loaded state and a spring-loaded state of adjacent contact elements of another preferred embodiment of a test busbar according to the present invention;

[0062] Figure 11 shows a perspective side view of a preferred embodiment of a testing device according to the present invention; and

[0063] Figure 12 A perspective side view of a connecting element of a test device for selectively fastening a corresponding test element or a test busbar in the test device is shown. DETAILED DESCRIPTION

[0064] Refer to the following Figures 1 to 3 A preferred embodiment of a test busbar 10 according to the present invention will now be described. The test busbar 10 comprises an elongated, sheet-like base body 2 extending in a longitudinal extension direction L and a plurality of contact elements 3 fastened to and integrally formed with the base body 2. The contact elements 3 extend substantially perpendicularly to the longitudinal extension direction L, in particular in a height direction H of the test busbar 10. In this case, the contact elements 3 are preferably arranged equidistantly from one another in the longitudinal extension direction of the base body 2.

[0065] The base body 2 has a preferably uniform thickness t. The height of the base body 2 may also be uniform. The base body has projections 6, preferably arranged on both sides of its ends, which can be used to electrically contact the test busbars 10. These projections 6 include electrical connection means 6a, such as corresponding openings or holes, for making electrical contact via corresponding connection elements.

[0066] The base body 2 further comprises mounting means 7 for connection to the testing device 30 , which are preferably arranged on both sides in the longitudinal extension direction, for example mounting openings or mounting holes respectively arranged on the end sides.

[0067] Furthermore, the base body 2 can have a plurality of further holes 8, preferably centrally arranged, which preferably have uniform dimensions. These further holes 8 can be provided to reduce weight. Furthermore, this can optimize the galvanic coating process for the test busbar during production, in particular by achieving material savings due to surface reduction.

[0068] The contact elements 3 each have a linear contact section 4 arranged at the end, which extends parallel to the longitudinal extension direction L of the base body 2 over a predefined length L1 so that at least two and preferably a maximum of three parallel-running finger electrodes 11 of the solar cell S to be tested can be contacted by pressing. The finger electrodes 11 are preferably contacted in a direction perpendicular to the parallel arrangement of the finger electrodes during the test (see Figure 3In this case, the contact segments 4 are arranged such that the distance a between adjacent contact segments 4 along the longitudinal extension direction L is less than 0.4 mm, preferably less than 0.2 mm. Each contact segment 4 preferably has a uniform thickness b. The thickness b is preferably 0.1 mm to 0.2 mm, more preferably 0.13 mm to 0.18 mm.

[0069] In a preferred embodiment, the contact section 4 and the associated spring element 5 preferably have substantially the same thickness b. The contact section 4 and / or the spring element 5 preferably have a substantially rectangular cross section.

[0070] The finger electrodes 11 are contacted in particular via a linear or flat support surface 4c of the corresponding contact section 4, which is located on the side of the contact section 4 facing away from the base body 2. The support surface 4c extends between two ends 4a, 4b of the contact section 4, which are preferably formed at a right angle to the support surface 4c.

[0071] A spring element 5 is arranged between the base body 2 and the contact section 4 of the contact element and extends in a meandering manner between the base body 2 and the contact section 4 and lies in one plane with the base body 2 and the contact section 4. In this case, the spring element 5 has a multi-bend extension in a side view, i.e., viewed perpendicularly to the longitudinal extension of the test busbar 10, with a width extension B, wherein the width extension B parallel to the longitudinal extension L of the base body 2 is greater than the length L1 of the contact section 4 assigned to the spring element.

[0072] Here, the width extension B of the spring element 5 preferably extends beyond at least one, more preferably two, surface boundary lines E1, E2 of a virtual rectangular projection surface E, which is arranged between the respective linear contact section 4 and the base body 2 arranged parallel to the contact section 4. In this case, the respective boundary lines E1, E2 of the projection surface E abut against the opposite ends 4a, 4b of the linear contact section 4 and are oriented perpendicularly to the linear extent of the section 4.

[0073] The elastic element 5 extends from a first end 4a of the contact section 4 , preferably at a right angle to the support surface 4c of the contact section 4 , and extends in a meandering manner to the opposite base body 2 , being arranged rearward relative to the support surface 4c .

[0074] The spring element 5 has first and second curved sections 5a, 5b and a third curved section 5c located between the first and second curved sections 5a, 5b. The first and second curved sections 5a, 5b preferably have the same first bending radius r1, and the third curved section 5c has a second bending radius r2. The bending radius r2 is preferably greater than or less than the bending radius r1. The bending radius r2 is preferably greater than the bending radius r1. The curved sections 5a, 5b, 5c of the spring element 5 extend between the base body 2 and the contact section 4 in alternating bending directions. In an alternative embodiment of the spring element 5 (see Figure 10a 、 Figure 10b ), the first and second curved sections 5a, 5b have a curvature radius r1 which is greater than the curvature radius r2 of the interposed third curved section 5c.

[0075] The first and second curved sections 5a, 5b form a substantially quarter-circular arc segment. The third curved section 5c forms a substantially semicircular arc segment. Between the first and second curved sections 5a, 5b and the third curved section 5c, the spring element preferably each has a linear section 5d, which is arranged substantially parallel to the longitudinal extension direction L1 of the contact section 4. Alternatively, the curved sections can also be offset from each other without an intervening linear section.

[0076] like Figure 2 As shown, the corresponding spring elements 5 of adjacent contact elements 3 are arranged so that the spring elements 5 partially engage one another without touching. In particular, in a side view of the test busbar 10, the corresponding width extensions B of adjacent contact elements 2 overlap. In this case, for example, the third bend 5c of the spring element 5 is arranged so as to be interposed with respect to the first and second sections 5a, 5b of the adjacent spring element. Each spring element 5 preferably has a uniform width b. This width b is preferably configured uniformly with the width b of the associated contact section 4.

[0077] Figure 4a 、 Figure 4b The figures show adjacent contact elements 3 of a test busbar 10 according to the invention in their non-spring-loaded, in particular non-contacting, and spring-loaded, in particular contacting, states under a predefined applied force K in a direction perpendicular to the longitudinal extension directions L, L1. As shown in the figures, the spring elements 5, which are arranged partially interlocking, are designed such that, even with a predefined travel h, they preferably do not contact one another when contacting the solar cells S. When the spring elements are compressed in the direction of the force K, the width extension B of the spring elements 5 preferably does not change, or in particular increase.

[0078] The corresponding spring element 5 is preferably designed so that the force line F generated by the spring element 5 when contacting the solar cell intersects the contact section 4 at the second distal end 4b of the contact section 4 in a direction perpendicular to the longitudinal extension direction L1 of the contact section 4 or abuts against the second distal end 4b.

[0079] Figure 5 A perspective side view of a preferred embodiment of a test element 20 according to the present invention is shown, which has two test busbars 10a, 10b according to the present invention as described above. The test busbars 10a, 10b are arranged side by side in a transverse direction, i.e., in a thickness direction extending perpendicularly to the longitudinal extension direction L of the base body 2. The test busbars 10a, 10b are arranged with longitudinal extension directions or longitudinal orientations that are opposite to each other. The electrical connection elements 6a and / or mounting elements 7 arranged in the respective test busbars 10a, 10b are preferably oriented flush with each other.

[0080] like Figure 6 As shown, the test buses 10a, 10b are preferably arranged relative to each other in such a way that the meandering structures of the spring elements 5, 5' of the respective test buses 10a, 10b extend relative to each other. As a result, an overlap of the contact sections 4, 4' of the adjacently arranged test buses 10a, 10b is achieved, thereby achieving an optimized contacting of the finger electrodes 11. In particular, the respective test buses 10a, 10b are arranged in such a way that the distance a between two contact sections 4 arranged adjacent in the longitudinal direction of the first test bus 10a is equal to the distance a between the two contact sections 4' of the second test bus 10b arranged opposite each other in the side view, i.e., as shown in FIG. Figure 6 The covering is shown orthogonal to the longitudinal extension direction. This arrangement enables effective detection and contacting of all electrode fingers of the solar cell along the longitudinal extension of the test busbar or the test element.

[0081] like Figure 5 and Figure 6 As shown, the two test busbars 10a, 10b preferably overlap in a side view such that their respective spring elements 5, 5', in particular their respective third curved and preferably semicircular sections, form a plurality of circular structures 14 arranged in a row and partially overlapping in the longitudinal direction.

[0082] Figures 7a to 7c A further preferred embodiment of a test element 20 ′ according to the invention is shown, which has a plurality of test busbars 10 a , 10 b , 10 c and lateral protection elements 13 a , 13 b . Figure 7a The connection of the individual components of the test element 20' to the fastening means 21 provided therefor is shown, which can be guided through the corresponding mounting openings 7 of the test busbar 10 and fastened there. Figure 7bAs shown, the test element 20' has a uniform thickness t1, which is preferably 0.5 mm to 1 mm, and more preferably 0.6 mm to 0.8 mm.

[0083] Figure 7c An exploded view of this embodiment is shown, which has the previously described first and second test busbars 10a, 10b, which are preferably arranged directly adjacent to each other with opposite longitudinal extension directions or longitudinal orientation. The test element 20' also has a third test busbar 10c, which is electrically separated from the first and second busbars 10a, 10b by a similarly provided insulating busbar 12. Thus, current measurements or current intensity measurements can be performed during the test using the first and second test busbars 10a, 10b, and voltage measurements can be performed using the third test busbar 10c.

[0084] The test element 20' can further comprise two outer protective elements, in particular thin-walled protective plates 13a, 13b, which preferably frame the test busbars 10a, 10b, 10c arranged between them in such a way that, in particular, only the contact section 4 and the associated spring element 5 of the respective test busbar protrude only partially in a side view of the test element 20', and the remaining part of the test busbar is thus covered by the protective elements in a side view. The protective plates 13a, 13b preferably have a matte and / or dark, preferably black, surface, thereby further minimizing any negative influence on the test quality.

[0085] Figure 8a An exploded view of another preferred embodiment of a test element 20 ″ according to the present invention is shown, which has a similar structure to that according to the present invention. Figures 7a to 7c The embodiment of the present invention is characterized in that a plurality of, preferably three, test busbars 10a, 10b, 10c are arranged. Figures 7a to 7c In contrast to the embodiment of the present invention, this embodiment does not have protective elements 13a, 13b, but rather has a coating 22 applied to the respective external test busbars 10a, 10c, which has a matte and / or dark surface. The coating 22 is preferably applied at least to the respective outer surface of the base body 2.

[0086] Figure 8bAn exploded view of another preferred embodiment of a test element 20''' according to the invention is shown, which has a symmetrical arrangement of test busbars 10. In this case, the test element 20''' includes, in addition to first and second test busbars 10a, 10b, at least one third test busbar 10c and two insulating busbars 12a, 12b. The first test busbar 10a is arranged in a sandwich-like manner between the two insulating busbars 12a, 12b, and the second and third test busbars 10b, 10c are each arranged externally on the insulating busbars. Optionally, further adjacent test busbars 10d, 10e can be arranged on the respective external test busbars 10a, 10b, preferably without intermediate elements.

[0087] The test busbars 10a-10e form a symmetrical layered structure of the test element 20''. The test busbars 10b, 10d and 10c, 10e, which are arranged directly adjacent to each other, are preferably arranged such that the distance between two contact sections 4 of adjacent first test busbars 10b, 10c, which are arranged adjacent to each other in the longitudinal direction, is covered by the opposite or identically arranged contact section of an adjacent second test busbar 10d, 10e.

[0088] Figures 9a to 9c The exploded view, side view and detail view of another preferred embodiment of the test element according to the invention are shown, which has at least two test busbars 10a, 10b with an identically directed or equidirectional arrangement of the corresponding spring elements 5 or contact elements 3. In this case, Figure 9c As shown, the contact elements 3, which are arranged in the same direction or in the same direction with respect to the meandering design of the spring elements 5 and the linear extension of the contact sections 4, are arranged such that the distance a between two contact sections 4 arranged adjacent in the longitudinal direction of the first test busbar 10a is covered by the identically arranged contact sections 4' of the second test busbar 10b. In particular, the respective contact elements 3 of the first test busbar 10a are arranged offset relative to the contact elements 3' of the second test busbar 10b in the longitudinal direction of the base body 2.

[0089] Figure 10a 、 Figure 10b shows the non-spring loaded state and the spring loaded state of the adjacent contact elements 3 of another preferred embodiment of the test busbar 10 according to the invention, similar to the embodiment according to Figure 4a 、 Figure 4b In this case, unlike Figure 4a 、 Figure 4bThe respective contact element 3 has first and second curved sections 5a, 5b and a third curved section 5c located between the first and second curved sections 5a, 5b. The first and second curved sections 5a, 5b have substantially the same first curvature radius r1, and the third curved section 5c has a second curvature radius r2. In this case, the second curvature radius r2 is smaller than the first curvature radius.

[0090] Figure 11 A preferred embodiment of a test device 30 according to the present invention is shown, which has a plurality of test elements 20 arranged parallel to one another, as described above. The test device 30 has a rectangular carrier frame 31 for selectively fastening the test elements 20 or test busbars 10. The test elements 20 or test busbars 10 are oriented parallel to one another in the test device 30. The device may also have electrical connection means, such as correspondingly designed connection elements (not shown), for electrically contacting the individual test elements 20 or test busbars 10, in particular via their corresponding electrical connection means 6a.

[0091] The carrier frame 31 preferably comprises correspondingly oppositely arranged connecting elements 32 for easily fastening the respective test element 20 or test busbar 10 by means of the fastening means 21 assigned thereto (see also Figure 12 ), these fastening means 21 can be guided through the corresponding mounting openings 7 of the test busbar 10 and fastened there. In particular, the cylindrical fastening cylinders 21a (see Figure 7a ) can interact with the two receiving grooves 32a of the corresponding connecting element 32 arranged on the side of the central push-in piece 32b for holding purposes.

Claims

1. A test busbar (10) for releasably electrically contacting a solar cell having a conductive substrate, comprising: An elongated sheet-like base body (2), the base body (2) having a plurality of contact elements (3) arranged on one side thereof and integrally formed with the base body; in, The contact elements (3) each have a linear contact section (4) arranged on the end side, the contact section (4) extending with a predefined length (L1) parallel to the longitudinal extension direction (L) of the base body (2); and A spring element (5) is arranged between the base body (2) and the contact section (4), the spring element (5) extending substantially perpendicularly to the longitudinal extension direction (L) of the base body (2) in a meandering manner between the base body (2) and in a plane with the base body (2) such that a width extension (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 the contact section (4).

2. The test bus according to claim 1, wherein: Solar cells do not have busbars.

3. The test bus according to claim 1, wherein: The contact section (4) is plate-shaped and has a linear support surface (4c) facing away from the base body (2) for contacting the conductive substrate, the support surface (4c) extending between two ends (4a, 4b) of the contact section (4) which are formed at right angles to the support surface (4c).

4. The test bus according to claim 1 or 3, wherein: The spring element (5) extends away from a first end (4a) of the contact section (4) which is formed at a right angle to the support surface (4c) of the contact section (4) and a side of the contact section (4) facing away from the support surface (4c).

5. The test bus according to claim 1, wherein: The spring element (5) is designed such that a force line (F) generated by the spring element (5) when contacting the solar cell intersects the contact section (4) at a second distal end (4b) of the contact section (4) in a direction perpendicular to the longitudinal extension direction of the contact section (4) or abuts against the second distal end (4b). The test bus according to claim 1 , wherein: The spring element extends with its width extension (B) at least through a surface boundary line (E1, E2) of a virtual rectangular projection surface (E) between the linear contact section (4) and the base body (2) arranged parallel to the contact section (4).

7. The test bus according to claim 1, wherein: The spring element (5) has first and second curved sections (5a, 5b) curved in the same direction and a third curved section (5c) located between the first and second curved sections (5a, 5b) and curved in a direction opposite to the direction.

8. The test bus according to claim 7, wherein: The spring element (5) has a first and a second curved section (5a, 5b) and a third curved section (5c) located between the first and the second curved sections (5a, 5b), the first and the second curved sections (5a, 5b) having the same first curved radius (r1), and the third curved section (5c) having a second curved radius (r2) that is larger or smaller than the first curved radius (r1).

9. The test busbar according to claim 7 or 8, wherein: The first and second curved sections (5a, 5b) are substantially quarter-circle arc sections, and the third curved section (5c) is substantially semi-circle arc section.

10. The test busbar according to any one of claims 7 or 8, wherein: The spring element (5) has a linear section (5d) between the first and / or second curved section (5a, 5b) and the third curved section (5c), wherein the linear section (5d) is arranged substantially parallel to the longitudinal extension direction (L1) of the contact section (4).

11. The test bus according to claim 10, wherein: The linear section (5d) has a length that is 20% to 30% of the length (L1) of the contact section.

12. The test bus according to claim 1, wherein: The bent section of the spring element (5) extends between the base body (2) and the contact section (4) with alternating bending directions.

13. The test bus according to claim 1, wherein: The spring element (5) is designed such that it achieves a travel (h) of 0.8 mm to 2.0 mm in a direction perpendicular to the longitudinal extension (L) of the base body (2) without changing the width extension (B) of the spring element (5).

14. The test bus according to claim 1, wherein: The spring element has a spring force of less than 0.4N.

15. The test bus according to claim 1, wherein: The spring elements (5) of the contact element (3) are arranged in such a way that spring elements (5) arranged adjacent to each other in the longitudinal extension direction (L) partially engage with each other.

16. The test bus according to claim 1, wherein: The spring elements (5) are arranged in such a way that no contact between adjacent spring elements (5) occurs in the case of a predetermined travel (h) in a direction perpendicular to the longitudinal extension (L) of the base body (2).

17. The test bus according to claim 1, wherein: The spring element (5) and / or the contact section (4) are of plate-shaped design and have a uniform width (b).

18. The test bus according to claim 1, wherein: The length (L1) of the contact section (4) is designed such that the contact section (4) can contact at least two electrically conductive substrates of a solar cell (S) extending perpendicularly to the contact section (4).

19. The test bus according to claim 1, wherein: The contact section (4) has a length (L1) of 2.5 mm to 3 mm, and / or Wherein, the distance (a) between adjacent contact sections (4) along the longitudinal extension direction (L) is less than 0.4 mm.

20. The test bus according to claim 1, wherein: The contact element (3) extends from the base body (2) over a distance (d) of 6 mm to 20 mm.

21. The test bus according to claim 1, wherein: The test busbar (10) has a uniform thickness (t) of 0.1 mm to 0.25 mm and / or is constructed in one piece.

22. The test bus according to claim 1, wherein: The contact elements (3) of the test busbar (10) are arranged equidistant from one another along the longitudinal extension direction (L) on the base body.

23. A test element (20) comprising at least two test busbars according to any one of claims 1 to 22, wherein: The test busbars are arranged adjacent to each other in a transverse direction and in opposite or identical longitudinal extension directions (L), so that the meandering formations of the spring elements (5) of the test busbars are arranged opposite or in the same direction, and / or the distance (a) between two contact sections (4) arranged adjacent to each other in the longitudinal direction of a first test busbar (10a) is covered by opposite or identically arranged contact sections (4') of a second test busbar (10b).

24. The test element according to claim 23, wherein the test busbars further comprise at least one third test busbar (10c) and an insulating busbar (12), wherein the insulating busbar (12) is arranged interleaved with respect to the adjacent first and second test busbars in a lateral direction.

25. The test element according to claim 23, wherein the test busbars further comprise at least one third test busbar (10c) and two insulating busbars (12a, 12b), wherein: The first test busbar (10a) is arranged in a sandwich-like manner between the two insulating busbars (12a, 12b), and the second and third test busbars are each arranged externally on the insulating busbars (12a, 12b).

26. A test element according to any one of claims 23 to 25, comprising two outer protective plates (13a, 13b) having a matte and / or dark surface for minimizing reflections, and / or the two outer protective plates (13a, 13b) frame the test busbar arranged between the two outer protective plates (13a, 13b) in such a way that the contact section (4) of the test busbar protrudes completely in a side view of the test element (20) and the spring element (5) protrudes at least partially.

27. The test element according to any one of claims 23 to 25, wherein The outer test busbar of the test element has a matte and / or dark coating (22) for minimizing reflections, and the coating (22) is arranged in such a way that it completely covers the outer surface of the base body (2) of the test busbar.

28. A test device (30) comprising a plurality of test elements (20) arranged parallel to one another according to any one of claims 23 to 27 and a rectangular carrier frame (31) for selectively fastening the test elements (20).

29. Use of a test busbar (10) according to any one of claims 1 to 22, a test element (20) according to any one of claims 23 to 27 or a test device (30) according to claim 28 for checking a solar cell (S) without a busbar, said use being achieved by electrically contacting finger electrodes (11) arranged in parallel on the surface of the solar cell and simultaneously exposing the solar cell to light.

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