WO2019086075A1

WO2019086075A1 - Contacting element and device for temporarily contacting a solar cell

Info

Publication number: WO2019086075A1
Application number: PCT/DE2018/100881
Authority: WO
Inventors: Michael QUINQUE; André Schwingel; Björn Reiche
Original assignee: Hanwha Q Cells Gmbh
Priority date: 2017-11-02
Filing date: 2018-10-29
Publication date: 2019-05-09
Also published as: DE102017125626A1

Abstract

The invention relates to a contacting element (100) for a device (50) for temporarily contacting a solar cell or a photovoltaic module, wherein said contacting element (100) has an elongate contacting stamp (110) for electrically contacting the solar cell or the photovoltaic module, under pretension, at at least one position.

Description

Contacting element and device for temporary

Contacting a solar cell

The present invention relates to a contacting element and a device for temporarily contacting a solar cell or a photovoltaic module. In particular, the invention relates to a contacting device having segmented spring-loaded contact stems or contact bars for contacting solar cells during a measurement (for example, for detecting a current-voltage characteristic or an electroluminescence measurement).

background

Frequently, at the end of the solar cell production, a test is carried out on the solar cells in order to determine their quality and to classify them according to the determined characteristic data. For this purpose, a temporary electrical contact with at least one solar cell or a part of the finished photovoltaic module is usually produced in order to carry out corresponding measurements. Various measurement technologies are available to determine different solar cell properties. These are, for example, electroluminescent image representations, thermal imaging or the detection of a current-voltage characteristic.

In the electroluminescent image display, the inverse principle of the photovoltaic module cells is used, ie a corresponding current or a corresponding voltage is applied to the cells and the generated radiation (electroluminescence) is detected by a camera system. In this way, it can be determined which solar cells or which parts of solar cells have a sufficient quality and which only have a lower quality. When acquiring the current-voltage characteristic, the solar cells can be irradiated with an artificial light source and an electrical contacting system can be used together with electronic measuring devices to measure and test the solar cells accordingly. Solar cells / photovoltaic modules are typically electrically contacted on a front side via narrow contact fingers which extend parallel to the front side starting from optional current bus bars. The contacting from the rear side takes place, for example, via a backside metallization (for example, if no light is incident therefrom). However, it is likewise possible that the semiconductor material of the solar cell / photovoltaic module is also electrically contacted from the rear side via current busbars / contact fingers.

Both in the electroluminescence measurement and in the detection of the current-voltage characteristic, it is important that the active areas of the solar cell surface can be measured reliably with the electrical contact system. An optimal electrical contacting system is therefore able to contact only inactive areas and to create only minimal shadow on the active areas. Moreover, in detecting the current-voltage characteristic, it is important to make an electrical contact comparable to the use of soldered contact fingers. In particular, the contact resistance should be very low (i.e., comparable to a solder joint) and the contact points should be evenly distributed.

So far, essentially two contacting systems are known: spring-biased contacting elements (see WO 2012/127411) and bent wires (see DE 10 2008 038 184 Ai), both of which are already used for the electrical contacting of solar cells. Spring biased styli include acicular pins biased in telescoping tubes with springs. For contacting the solar cells, a plurality of these spring-biased feeler elements are fixed and aligned via a carrier element. The contact areas are very small compared to the contact fingers.

Fig. 4 shows such a conventional contacting device based on acicular pins for electrically contacting solar cells, wherein a plurality of punctiform contacting elements 400 are arranged along a row. The contacting elements 400 are alternately applied with a voltage value, wherein interposed contacting elements 400 dissipate a current signal, so that a current-voltage characteristic for different areas can be detected. Thus, for a measuring strip, a four-point measurement can be carried out in which, for example, a known current flows between two contacting elements and two further contacting elements are used to measure a voltage drop present there (or vice versa). All contacting elements can also serve for current measurement / current injection. The measuring bar should have a good conductive material.

A disadvantage of these conventional contacting elements 400 is that the contacting accuracy is insufficient. Thus, it is often difficult to contact with the needle-shaped contact pins exactly the contact fingers of the solar cells. Likewise, it often happens that the individual contact pins when moving a contact pressure easier to move or twist and thus do not allow accurate measurement.

Therefore, there is a demand for improved contacting possibilities of solar cells or photovoltaic modules which do not have the above-mentioned problems.

Summary

The above object is achieved by a contacting element according to claim 1, a device according to claim 7 and a use of the Kontaktierungselemen- tes or the device. The dependent claims relate to advantageous developments of the contacting element according to claim 1 or the device according to claim 7.

The present invention relates to a contacting element for a device for temporarily contacting a solar cell or a photovoltaic module. The contacting element comprises a longitudinally shaped contact stamp for electrically contacting the solar cell or the photovoltaic module under a bias voltage at at least one position.

Optionally, the contacting element for electrical connection of the Kon- taktstempels a rod-shaped connecting element with two parts which are movable into each other and are biased by a spring (eg in the form of a telescopic spring).

The elongate contact stamp comprises two opposite long sides and two opposite short sides (the short side being shorter than the long side), wherein optionally latching elements are provided on the two opposite short sides, so that the contact stamp with other contact punches in at least one direction positively is connectable to achieve a stable linear alignment of the contacting elements. For example, the latching elements may have a projection and a recess, wherein the recess is designed to hold the projection in at least one direction in a form-fitting manner.

Optionally, the contact stamp includes a patterned bonding surface that includes one or more edges or peaks to increase the contact pressure during temporary bonding (e.g., formed to be sufficiently acute).

Optionally, the contacting element comprises one or more insulating regions formed to provide lateral electrical isolation to adjacent contacting elements.

Optionally, the elongate shaped contact punch comprises a first length along a longitudinal direction in a range between 3 and 10 mm, a second length in a transverse direction between 0.5 and 3 mm and a thickness in a range between 1 and 3 mm.

The present invention also relates to a device having a plurality of contact elements as defined above, a contact carrier and electrical supply lines. The contact carrier is designed to hold the contacting elements along a straight or curved line. The electrical supply lines are configured to impress or tap current values or voltage values at different positions on the solar cell or the photovoltaic module. Optionally, the contact carrier is designed to alternately apply or pick off a first electrical variable, in particular specific electrical voltage values, and a second electrical variable, in particular electrical current values, at the contacting elements. Therefore, the contacting elements can be used alternately for measuring / applying a voltage and for adding or removing charge carriers (current measurement). For example, a pair of contacting elements may each comprise a so-called current-carrying contacting element and a voltage-measuring contacting element. It is also possible to use a measurement bar for a four-point measurement. Likewise, all contacting elements can be used for current measurement / current application or for voltage measurement / voltage application. Advantageously, the measuring strip comprises a good conductive material.

Optionally, the contact carrier comprises a first carrier element and a second carrier element, which each hold at least one electrical contacting element and are designed to electrically contact the solar cell or the photovoltaic module on opposite sides (in particular at different positions).

The present invention also relates to a use of at least one contacting element in a device as defined above or a corresponding method for determining characteristic data of at least one solar cell in a measuring device using the contacting element and the device.

Embodiments of the present invention provide the following advantages:

The segmented spring-loaded contact punches can in particular enable a continuous contact along a line and also offer a high mechanical stability and security against rotation. This compensates the positioning inaccuracies of a machine so that reliable contacting is always possible. It is possible to contact solar cells with arbitrarily shaped current busbars (busbars) or without current busbars. Compared to conventional contacting devices, the number of contact be reduced due to the bar or stamp form. Likewise, a better distribution of force is achieved by the contact stamp. This minimizes the risk of breakage. Thus, embodiments allow for better electrical contacts, more accurate electrical measurements, improved process feedback (poor manufacturing quality can be quickly detected), and long life (because of higher production quality).

The choice of contact stamp allows an uninterrupted contact line, but in the contacting direction anyway due to the suspension can adapt to an uneven surface. Thus, for example, after every 3-5 mm height adjustment by the respective following contact stamp done.

Brief description of the figures

The embodiments of the present invention will be better understood from the following detailed description and the accompanying drawings, which should not be construed as limiting the disclosure to the specific embodiments but are for explanation and understanding only.

Fig. 1 shows an apparatus for temporarily contacting a solar cell according to an embodiment of the present invention.

FIGS. 2A, 2B show a side view and a plan view of a contacting element according to one exemplary embodiment.

3 illustrates the juxtaposition of a plurality of contacting elements.

Fig. 4 shows a conventional contacting profile for contacting a

Solar cell. Detailed description

1 shows a device 50 for temporarily contacting a solar cell or a photovoltaic module (not shown in FIG. 1). The device 50 comprises a plurality of contacting elements 100, each having a longitudinally shaped contact stamp 110 and being designed to electrically contact the solar cell or the photovoltaic module under a bias voltage at at least one position. The contacting elements 100 each comprise a rod-shaped connecting element 120 for electrically connecting the contact stamps 110, wherein the connecting element 120 may have a spring (not visible in FIG. 1) for applying the prestressing. In this way, a variety of telescopic springs. In addition, device 50 includes a contact carrier 130 for holding the contacting elements 100 along a line and for impressing or tapping current values or voltage values at different positions on the solar cell or the photovoltaic module.

The contacting elements 100 are thus formed in the embodiment shown as a spring-loaded Kontaktierungsstifte that can compensate for unevenness on the surface of the solar cell / photovoltaic modules and provide sufficient contact pressure for secure contact.

As shown in FIG. 1, the contacting elements 100 may extend through the contact carrier 130 so as to be electrically contacted on the back side of the contact carrier 130. As a result, the contact carrier could be made easier, with a flexible contacting is still possible. However, this is not necessarily so. It is also possible that the electrical leads are formed in the contact carrier 130.

FIG. 2A shows a side view of a contacting element 100 for contacting the solar cell or the photovoltaic module according to one exemplary embodiment. The contacting element 100 comprises the contact stamp 110 and a rod-shaped connecting element 120 which, for example, has an external thread 121 on a side opposite the contact stamp 110, in order to provide the contacting screw element 100 into a corresponding carrier 130. In other embodiments, no external thread 121 is provided. Instead, the connecting elements 120 can be inserted into the carrier 130 (eg, using a snap closure). The connector 120 also includes a first portion 122 and a second portion 123 telescopically slidable with a spring (not visible in FIG. 2) formed in the connector 120 for biasing the connector 120 under a bias hold.

Fig. 2B shows a top view of the contact stamp 110, which is designed substantially rectangular with a long side of the length Li and a short side of the length L2. On the short side, a recess (notch) 111 is formed and on the opposite short side, a projection 122 is provided. The recess 111 is formed such that it could receive the projection 112. Thus, a plurality of the contacting elements 100 shown may be arranged along a line, with the respective projections 112 engaging the respective recesses 111, so that a stable fixation along the longitudinal direction is achieved.

The shape of the projection 112 or recess 111 can be chosen arbitrarily. In Fig. 2B, the protrusion 112 and the recess 111 are made square (or rectangular). However, the present invention should not be limited to any particular form of the contacting elements. Rather, any shapes can be formed, as long as they allow electrical contacting of the solar cells. Thus, it is also possible that the projection 112 and the recess 111 have a semicircular shape or a triangular shape or any other shape. It is also possible that the protrusion 112 is head-shaped with a neck-like taper. If the recess 111 is designed to enclose the head-like projection 112, the contact punches 110 can be placed on each other as in puzzle pieces, thus providing high stability (e.g., displacement of the contacting device).

The contact stamp 110 is significantly wider along the long side (eg by more than twice) as the diameter d of the connecting element 120. This makes it possible to reduce the number of contacting elements 100 to be provided. For example, the contact stamp 110 along the long side have a length Li of about 6 mm or in a range between 4 and 10 mm. The length L2 of the short side is for example 2 mm or in a range between 1 and 4 mm. The diameter d of the connecting element 120 may for example be in a range between 1 and 3 mm or about 2 mm. The contact stamp 110 may also have a thickness or depth B of 1 to 3 mm or about 2 mm. These dimensions are only an example, the invention should not be limited to certain dimensions. In general, the dimensions of the contact stamps 110 can be adapted to the specific requirements.

This beam-like shape of the contacting elements 100 ensures that neither incident light nor light emitted by the solar cell is shaded during contacting.

In addition, the contact stamp 110 may have a contacting surface with a surface structure 115, which facilitates contacting of the solar cell or of the photovoltaic module or of corresponding finger contacts / busbars. For example, surface structure 115 may include a plurality of tapered pyramidal structures to achieve reliable electrical contact. To this end, the textured bonding surface 115 may include one or more edges or peaks to increase the contact pressure during temporary bonding (e.g., by selecting the edges / peaks to be sharp or fine, respectively).

Fig. 3 illustrates the juxtaposition of a plurality of Kontaktierungs- elements 100 which mutually engage on the projections 112 and recesses 111 with each other to form a line-shaped Kontaktierungsreihe. This makes it possible to contact the exemplary solar cell or the photovoltaic module at various points electrically linear.

The individual contacting elements 100 can now be connected to supply lines 210, 220 are electrically contacted to impress corresponding electric signals on the solar cell or the photovoltaic module or tap. By way of example, an electrical voltage can be applied to each second contacting element 100a via a first supply line 210 (for example, ground or an electrical voltage can be tapped there), while a corresponding current signal is fed or generated by the contacting elements 100b arranged therebetween via the second supply line 220 Electricity (eg at a light irradiation) is tapped. The individual contacting elements 100a, 100b or a part thereof can be electrically connected to one another. However, it is also possible that at least some of them are controlled separately, for example by each or many contacting elements 100 receive their own, independent electrical supply line. However, it is also possible for all the contacting elements 100 to be used for current measurement (or current injection) or for voltage measurement (or voltage application).

For example, with three adjacent contacting elements 100, the middle contacting element 100b may serve for signal detection, while the two outer contacting elements 100a may be reference elements, e.g. to generate the reference signal with a defined, non-interfering reference potential (e.g., ground potential) are applied.

With this arrangement, it is possible, for example, that all areas of the solar cell or the photovoltaic modules are set to a certain voltage or all areas a certain current is supplied. After that, the individual sections of the solar cell or of the photovoltaic module can be optically detected with a camera in order to be able to record the quality of the respective solar cell from the luminous intensity. The current can also be measured to determine the local current-voltage characteristic.

In order to be able to tap the measured values independently of one another, the contact stamps 110 can have insulations which are formed on the surface regions which are located between two adjacent contact stamps 110. After insertion of the projection 122 into the recess 111 of the As a result, both contacting elements 100 are electrically insulated from one another. For example, the surfaces between the contact punches 110 in FIG. 3 can be provided with an insulating surface coating for this purpose. Optionally, foil-like insulating elements can also be arranged between the contacting elements 110.

Optionally, it is also possible that the solar cell is contacted from two opposite sides. For example, the device as shown in FIG. 1 may contact the solar cell from a front side, while the back side of the solar cell may be electrically powered by a separate contact or also by a device 50 as shown in FIG will be contacted.

Embodiments allow the contacting device 50 to be mounted on a single connection, as well as the simultaneous contacting of a complex connection structure or a busbar. The parallel contact fingers can also be contacted with the described contact device 50. It is also possible to use the contacting device 50 for solar cells which have no current busbars. Likewise, the account assignment device 50 can be used for solar cells which are contacted exclusively via the rear side.

The present invention also relates to a use of the described contacting device 50 for measurements of characteristics of solar cells, e.g. at an automated measuring station, wherein the contacting device 50 is used for temporarily electrically contacting the front and / or back of the solar cells. For contacting the rear side, the contacting device 50 can be used in a mirror image, so that the solar cell is held between a first carrier element with contacting elements 100 and a second carrier element with further contacting elements 100.

The features of the invention disclosed in the description, the claims and the figures may be essential for the realization of the invention either individually or in any combination. LIST OF REFERENCE NUMBERS

50 contacting device

100, 100a, .. contacting elements

110 contact stamp

111 recesses

112 protrusions

115 structured contacting surface

120 rod-shaped connecting element

121 fasteners (e.g., threads)

122.123 parts of the connecting elements

130 contact carrier

210,220 electrical feeders

400 conventional punctiform contact elements

Li, L2 lengths of the contact punch

B depth / thickness of the contact stamp

Claims

claims

1. contacting element (100) for a device (50) for temporarily contacting a solar cell or a photovoltaic module, wherein the contacting element (100) has a longitudinally shaped contact stamp (110) to the solar cell or the photovoltaic module under a bias voltage at least one position electrically to contact.

2. contacting element (100) according to claim 1, further comprising for connecting the contact stamp (110) has a rod-shaped connecting element (120) with two parts (122, 123) which are slidable into each other and a spring for applying the bias voltage is provided.

3. Contacting element (100) according to claim 1 or claim 2, wherein the elongate contact stamp (110) has two opposite long sides and two opposite short sides, wherein on the two opposite short sides latching elements (111, 112) are provided, so that the Contact stamp (110) with further contact punches in at least one direction is positively connected to achieve a stable linear alignment of a plurality of contacting elements (100).

4. contacting element (100) according to one of claims 1 to 3, wherein the contact stamp (110) has a structured contacting surface (115), which comprises one or more edges or peaks in order to increase the contact pressure in the temporary contacting.

5. contacting element (100) according to any one of the preceding claims, further comprising insulating regions which are formed to provide a lateral electrical insulation to adjacent contacting elements.

6. contacting element (100) according to any one of the preceding claims, wherein the elongated shaped contact stamp (110) has a first length (Li) have a longitudinal length in a range between 3 and 10 mm, a second length (L2) in a transverse direction between 0.5 and 3 mm and a thickness (B) in a range between 1 and 3 mm.

7. A device (50) comprising: a plurality of contacting elements (100) according to one of the preceding claims; a contact carrier (130) configured to hold the contacting members (100) along a straight or curved line; and electrical supply lines (210, 220) for impressing or tapping current values or voltage values at various positions on the solar cell or the photovoltaic module.

8. Device (50) according to claim 7, wherein the contact carrier (130) is designed to alternately apply or pick off at the contacting elements (100) a first electrical variable, in particular specific electrical voltage values, and a second electrical variable, in particular electric current values ,

9. Device (50) according to claim 7 or claim 8, wherein the contact carrier (130) comprises a first carrier element and a second carrier element, each hold at least one electrical contacting element (100) and are formed to the solar cell or the photovoltaic module on opposite Contact sides electrically.

10. Use of at least one contacting element (100) according to one of claims 1 to 6 in a device (50) according to one of claims 7 to 9 for determining characteristic data of at least one solar cell in a measuring device.