WO2020212116A1

WO2020212116A1 - Solar cell arrangement

Info

Publication number: WO2020212116A1
Application number: PCT/EP2020/058711
Authority: WO
Inventors: Ansgar Mette; Florian Stenzel
Original assignee: Hanwha Q Cells Gmbh
Priority date: 2019-04-18
Filing date: 2020-03-27
Publication date: 2020-10-22
Also published as: DE102019110348A1

Abstract

A solar cell arrangement comprises a first solar cell (101) and a second solar cell (102), which overlap with one another in an overlap region (112) and each have contact fingers (420) for electrically contacting the individual solar cells (101, 102) and busbars (121, 122,...) for dissipating an electric current (I) from the contact fingers (420). The electric current (I) runs along the busbars (121, 122,...) from a main surface (101a) of the first solar cell (101) to an opposite main face (102b) of a second solar cell (102).

Description

Solar cell array

The present invention relates to a solar cell arrangement and a method of producing it, and in particular to overlapping solar cells.

BACKGROUND

In the manufacture of photovoltaic modules, a large number of solar cells are usually arranged next to one another to form so-called strings and connected accordingly. The individual solar cells are electrically connected to one another by means of bus bars or so-called ribbons. In addition, there are contact fingers for the individual solar cells in order to record the electricity generated in the surface and to derive it accordingly. The solar cells are often connected in series along the strings, so that the cell connections are routed from a front side of the solar cells to a rear side. FIGS. 4A and 4B show, by way of example, a conventional design of a solar cell, FIG. 4A showing a plan view and FIG. 4b showing a cross-sectional view along the cross-sectional line B-B. In the top view it can be seen that a multiplicity of contact fingers 420 are formed parallel to one another in the horizontal direction and are electrically contacted by what are known as busbars 450. The busbar 450, in turn, is connected to a busbar 440 via contact pads 430 (see Fig.

6B) electrically contacted. For this purpose, the contact pads 430 are formed in a recess in the busbar 450. The electrical connection is usually made using a soldered connection. The busbar 450, which is interrupted in the middle, show a cutting line along which the individual solar cell is cut. 4B shows the cross-sectional view along the cutting plane BB, which runs through a busbar 450. As can be seen from FIG. 4B, a plurality of contact pads 430, which are contacted by the busbars 440, are formed on a semiconductor material 410 (cell body). Between two neighboring A section of the busbar 450 can be seen in each case on the ten contact pads 430, which in turn makes contact with the contact fingers 410 (see FIG. 4A). The contact pads 430 are in an overlapping contact with the busbar 450 in the direction perpendicular to the plane of the drawing, so that the current is picked up by the individual contact fingers 420, passed on to the contact pads 430 and diverted via the busbar 440. The (conventional) busbars 440 connect, for example, a plurality of solar cells arranged in series.

When these solar cells are interconnected, however, the area between the individual solar cells is inactive and can only be used passively (e.g. by reflecting on a coating on the back) to generate electricity from the surrounding cells. For the interconnection, for example, 6 cell connectors are provided, which, however, are very thick due to the considerable current, so that pressure points occur on the cell edges. On the one hand, these pressure points prevent a small cell spacing or cause mechanical stresses at the edges of the solar cells. This can lead to breaks at the edge of the solar cells or small cracks can significantly reduce the electrical performance.

For solar cells without cell connectors there is already the option of partially arranging the solar cells one above the other (so-called shingles), which avoid the occurrence of possible micro-cracks at the edges of the solar cells or in the cell connectors. Here, the individual contact fingers of the solar cells are electrically connected to one another via a metalization in the edge area or an electrically conductive adhesive is used for the electrical connection. A disadvantage of this approach is that the current from the solar cell is conducted to the cell edge via the contact strips, which either requires narrow cell strips or leads to increased (serial and / or optical) losses. In addition, other materials are necessary in order to apply the conductive adhesive in the edge area with good electrical conductivity for all contact strips. In addition, the distances for the current discharge are significantly longer compared to cell connectors, which leads to series resistance losses, since the contact fibers are only very thin and are therefore not suitable for higher currents. Finally, the use of the silver paste is on the front is thus strongly limited.

There is therefore a need for new module designs and interconnections that overcome these disadvantages and, in particular, eliminate the distance between the individual adjacent solar cells. Brief description of the invention

At least some of the above-mentioned problems are solved by a solar cell arrangement according to claim 1 and a method for their production according to claim 8. The dependent claims relate to advantageous developments of the subjects of the independent claims. Embodiments relate to a solar cell arrangement with a first solar cell and a second solar cell, which overlap each other in an overlap area and each have contact fingers for electrically contacting the individual solar cells and busbars for carrying an electrical current from the contact fingers. The electrical current is conducted along the busbars from a first main surface of the first solar cell to an opposite, second main surface of the second solar cell. The solar cells used for this purpose can correspond to the conventional solar cells from FIGS. 4A and 4B, the busbars having to be adapted according to the exemplary embodiments (eg with regard to the position and / or length). The busbars can also be so-called cell connectors, ribbons, etc. According to embodiments, the busbars are to be distinguished from printed metallizations. These printed metallizations are, for example, the contact fingers, so-called busbars (see FIGS. 4A and 4B) or other structures that can be printed as a paste on the solar cells in order to collect the electrical current within a given solar cell. The busbars are electrically connected to these printed structures at one or more points (eg soldered, glued, pressed, etc.) and are used to transport the collected electrical current to the next solar cell or to an external power connection. Optionally, the respective busbars on the first main surface are arranged offset to one another compared to the respective busbars on the second main surface, so that in the overlapping area the busbars of the first solar cell and the busbars of the second solar cell are arranged next to one another or at a distance from one another.

Optionally, at least a part of the busbar runs continuously from the first solar cell to the second solar cell. In particular, the continuous busbars can run almost in a straight line and electrically connect the opposite main surfaces to one another. Optionally, the first solar cell and / or the second solar cell in the overlap area comprises a metallization in order to electrically connect the busbars to one another in the overlap area. As a result, the electric current is conducted from the first solar cell to the second solar cell via the busbars of the first solar cell, the metallization and the busbars of the second solar cell.

Optionally, spacers (support structures) are formed between at least two adjacent busbars in the overlap area in order to support a force acting perpendicular to the main surfaces or to support the solar cells on one another. This spacing is always of particular advantage when there are only relatively few (eg fewer than 15) busbars in the overlap area, since otherwise excessive forces could act on the individual busbars, which could damage the solar cell .

The spacers can also (at least partially) extend out of the overlap area in order to provide protection and / or support in the edge area of the overlap area. For example, the spacers can offer additional protection below the solar cell arrangement, where there is a step in the overlap area.

The material of the spacers can be chosen almost arbitrarily, as long as the desired support function is achieved. Possible materials for the spacers include a polymer material and in particular an electrically conductive polymer material. The spacers can also contact at least some of the busbars and, if they are themselves conductive, improve the flow of current (lower electrical resistance).

Optionally, the first solar cell and the second solar cell can be used on both sides to generate electricity. In particular, contact strips can also be formed on both sides.

Further exemplary embodiments relate to a method for producing a solar cell arrangement. The procedure consists of the following steps:

- Providing a first solar cell with Kontaktfmgern and current collector rails;

Providing a second solar cell with contact fingers and current collecting rails; and

Arranging the first solar cell and the second solar cell so that they overlap one another in an overlapping area and the busbars lead the current from the first solar cell to the second solar cell.

Optionally, the method also comprises forming spacers between at least two adjacent busbars in the overlap region in order to support a force acting perpendicular to the main surfaces. Optionally, the provision of a first solar cell and / or the provision of a second solar cell take place in such a way that at least a part of the busbar runs continuously from the first solar cell to the second solar cell. Therefore, the busbars can only extend over a solar cell or run from a solar cell (e.g. from a bottom) to an adjacent solar cell (e.g. on a top). Spacers (support structures) can be present between the busbars passing through in this way in order to absorb the pressure.

All of the aforementioned features of the solar cell arrangement can be implemented as further optional process steps. In particular, for the solar cell The usual arrangement of solar cells can be used, which were previously interconnected to form strings and then to modules. The only modifications that might be required are the relocation of the busbars on the rear side compared to the front side (= main light incidence side). Embodiments effectively overcome the above-mentioned problems in that adjacent solar cells overlap one another in a string direction (in the series connection). In other words, the previously existing distance between the solar cells has been shifted to a negative value. The active area in the module is increased and the module efficiency increases significantly. In addition, the risk of breakage of the cells in the module is reduced, since significantly lower or no mechanical stresses occur in the overlapping area, since the cells are supported on one another.

Embodiments achieve this through at least two configurations. On the one hand, the busbars can first be soldered to the individual solar cells. As a result, the electrical contact between the busbars and the contact fingers or other contact structures (e.g. contact pads, busbars) is established. The solar cells are then pushed over one another, for example in a so-called pick-and-place process. Another possibility is that the busbars run from one solar cell to the neighboring solar cell. Finally, the final soldering takes place. In order to absorb the pressure in these continuous busbars but also in the first variant (pre-soldered busbars), support structures (spacers) are provided according to exemplary embodiments, which ensure a predetermined minimum distance in order to prevent damage. BRIEF DESCRIPTION OF THE FIGURES

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

1 shows a solar cell arrangement according to an embodiment of the present invention.

Fig. 2 shows another embodiment with short Stromsammelschie NEN.

Fig. 3 shows another embodiment with long Stromsammelschie NEN.

FIGS. 4A, 4B show, by way of example, a conventional design of a solar cell.

DETAILED DESCRIPTION

FIG. 1 shows an exemplary embodiment for the solar cell arrangement with a first solar cell 101 and a second solar cell 102, which are arranged in an overlapping area 112 so as to overlap one another. The first solar cell 101 has contact fingers 420 (not visible in FIG. 1; see FIG. 4A) and busbars 121, which supply the electrical current that is generated by the solar cell and delivered to the contact fingers 420 collect and discharge accordingly. The second solar cell 102 also has contact fingers 420 and busbars 122, which likewise collect and divert the electrical current from the second solar cell 102. The contact fingers 420 are arranged vertically between the respective solar cell 101, 102 and the busbars 121, 122.

In addition, the first solar cell 101 comprises a first main surface 101a and a second main surface 101b. The same applies to the second solar cell 102, which likewise has a first main surface 102a and an opposing second main surface 102b. The overlapping arrangement of the first solar cell 101 and the second solar cell 102 takes place in such a way that the second main surface 101b of the first solar cell 101 is partially applied to the first main surface 102a of the second solar cell 102. This results in a series connection of the first solar cell 101 and the second solar cell 102, since an exemplary rear-side configuration clock (for example on the second main surface 101b) to a front side (for example the first main surface 102a of the second solar cell 102).

There are various options for this arrangement, the busbars NEN 121, 122, ... to lead. One possibility is that the busbars i2i, 122,... Each only extend along a given solar cell 101, 102.

2 shows such an exemplary embodiment in which the busbars 121 (or “1” for short) of the first solar cell 101 can be seen in the overlap area 112 in a cross-sectional view. In the exemplary embodiment shown, the busbars 1 are arranged offset from one another along the first main surface 101a compared to the busbars 1 along the second main surface 101b of the first solar cell 101. In the same way, the busbars 122 (or “2” for short) of the second solar cell 102 on its first main surface 102a are arranged offset in comparison to the busbars 2 on the second main surface 102b of the second solar cell 102.

The solar cells can thus be produced in an identical manner and placed one on top of the other, since the offset bus bars 121, 122, ... are arranged at different positions on the respective second main surface 101b, 102b, so that the between the first solar cell 101 and the Second solar cell 102 arranged busbars 1, 2 do not interfere with each other.

Optionally, it is possible that the busbars 1, 2, which are arranged in the overlap area between the first solar cell 101 and the second solar cell 102, contact one another. However, it is also possible that a metallization or an electrical conductor is provided in the overlap area 112, so that a current flow between the busbars 1, 2 arranged in between is possible, even if the busbars 1 of the first solar cell 101 do not align with the busbars 2 the second solar cell 102 are in direct contact. Fig. 3 shows a further embodiment in which the busbars 121, 122 are formed longer than the respective dimension of the solar cells 101, 102. For example, in Fig. 3, a first solar cell 101 and a second solar cell 102 and a third Solar cell 103 can be seen, with the second main surface 101b of the first solar cell and the first main surface 102a of the second solar cell

102 can be contacted by a common bus bar 121. The common busbar 121 thus extends over both the first solar cell 101 and the second solar cell 102 (runs continuously). In the same way, the second solar cell 102 and the third solar cell 103 are connected to one another in series, in that a continuous busbar 122 runs from the second main surface 102b of the second solar cell 102 to the first main surface 103a of the third solar cell 103.

Since in this exemplary embodiment the contact points between the overlapping solar cells 101, 102 are only half as large as in the exemplary embodiment in FIG. 2, support structures (spacers) 140 can optionally be provided that apply a pressure or a force perpendicular to the main surfaces 101a or 101b acts, can remove or support. This protects the solar cells 101, 102 from additional stresses or microcracks.

An advantage of the second exemplary embodiment is that no metallization is required in the overlap region 112, since the current rails 121, 122 passing through them conduct the current very well. This leads to further cost savings.

The solar cells 101, 102, ... can be designed with their contact fingers 420 and the optional contact pads 430 and / or busbars 450 like the conventional solar cells from FIG. 4A. The busbars 121, 122, ... can, however, deviate from the conventional design and can be made longer (see Fig. 3) or laterally on the top or bottom (see Fig. 2).

In further exemplary embodiments, it is also possible that the support structures 140 also between adjacent busbars 1, 2 from the execution Approximate example from FIG. 2 can be used in order to also reduce the mechanical stresses between the solar cells 101, 102 there. This is particularly useful when the number of busbars 121, 122 for the individual solar cells is relatively small (for example less than 10). If there are a lot of busbars 121, 122, the busbars 121, 122 themselves can provide sufficient support to adequately distribute the forces acting. It is then possible to dispense with the formation of support structures 140, since there is a homogeneous distribution of the voltages due to the large number of busbars 121, 122. The support structures 140 can in particular be elastic and comprise, for example, a polymer or an EVA material. However, the invention should not be restricted to specific materials of the support structures 140 - as long as these structures 140 show sufficient effect and the solar cells 101, 102 are reliably protected from cracks and similar stress-induced damage. It is also advantageous if the material of the support structures 140 is electrically conductive. The support structures 140 can be applied, for example, by screen printing, dispensing, dipping or the like.

According to further exemplary embodiments, the support structures 140 can also extend onto the underside (second main surface 101b, 102b) in order to also partially fill the step-shaped cavity there (due to the overlap). This can be useful in particular if the solar cells 101, 102 are only used on one side for power generation and the second main surface 102b, 101b represents a rear side. It should be noted, however, that the present invention is not intended to be restricted to a specific use of the solar cells. According to further exemplary embodiments, both sides can be used to generate electricity.

As with conventional solar cells, the busbars 121, 122 can be soldered to the individual solar cells, but the arrangement of the adjacent solar cells 101, 102 is changed according to exemplary embodiments. For example, the individual solar cells 101, 102 can first be soldered. When The result is the electrical contact between the busbars 121, 122 and the contact fingers 420 or further contact structures 430 (for example contact pads; see FIGS. 4A, 4B). Then the solar cells are pushed over one another. According to exemplary embodiments, this can be done in a so-called pick-and-place process. One advantage of this approach is that it allows the limitations of the screen printing metallization on the cell to be overcome. The staggered arrangement of the busbars 1, 2 on the front and on the back offers the advantage that further contact surfaces are formed, so that the contact pressure is reduced. The features of the invention disclosed in the description, the claims and the figures can be essential for realizing the invention both individually and in any combination.

REFERENCE CHARACTERISTICS LIST loi, 102, ... solar cells

ioia, 102a ... main surface (s)

ioib, i02b ... opposite main surface (s)

112 Overlap area of solar cells

121, 122, ... busbars

140 Spacers / Support Structures

410 cell bodies

420 contact fingers

430 contact pads

440 (conventional) busbar

450 bus bars I electrical current flow

Claims

EXPECTATIONS

1. Solar cell arrangement with a first solar cell (101) and a second solar cell (102) which overlap one another in an overlapping area (112) and each have contact fingers (420) for electrical contacting of the individual solar cells (101, 102) and busbars (121 , 122, ...) for discharging an electrical current (I) from the contact fingers (420), the electrical current (I) along the busbars (121, 122, ...) from a main surface (101a) of the first Solar cell (101) extends to an opposite main surface (102b) of a second solar cell (102).

2. Solar cell arrangement according to claim 1, wherein the respective busbars (121, 122) on the first main surface (101a, 102a) compared to the respective busbars (121, 122) on the second main surface (101b, 102b) are offset from one another are, so that in the overlap area (112) the busbars (121) of the first solar cell (101) and the busbars (122) of the second solar cell (102) are arranged next to one another or at a distance from one another.

3. Solar cell arrangement according to claim 1 or claim 2, wherein at least a part of the busbar (121, 122, ...) run continuously from the first solar cell (101) to the second solar cell (102).

4. Solar cell arrangement according to one of the preceding claims, wherein the first solar cell (101) and / or the second solar cell (102) in the overlap area (112) has a metallization to the busbars (121, 122) in the overlap area (112) electrically connected to each other to the electrical current (I) from the first solar cell (101) to the second solar cell (102) via the busbars (121) of the first solar cell (101), the metallization and the busbars (122) of the second solar cell (102) to conduct.

5. Solar cell arrangement according to one of the preceding claims, wherein between See at least two adjacent busbars (121, 122, ...) in the overlap area (112) spacers (140) are formed in order to support a force acting perpendicular to the main surfaces (101a, 101b).

6. Solar cell arrangement according to claim 5, wherein the spacers (140) at least partially extend out of the overlap area (112) in order to provide protection and / or support in the edge area of the overlap area (112).

7. Solar cell arrangement according to claim 5 or claim 6, wherein the spacers (140) have a polymer material and in particular an electrically conductive Po lymermaterial and / or at least partially contact some of the power supply rails (121, 122, ...).

8. Solar cell arrangement according to one of the preceding claims, wherein the first solar cell (101) and the second solar cell (102) are usable on both sides for generating electricity, in particular contact fingers (420) are ausgebil det on both sides.

9. A method for producing a solar cell arrangement with the following steps:

Providing a first solar cell (101) with contact fingers (420) and busbars (121);

Providing a second solar cell (102) with contact fingers (420) and busbars (122); and

Arranging the first solar cell (101) and the second solar cell (102) so that they overlap one another in an overlapping area (112) and the busbars (121, 122) convey the current (I) from the first solar cell (101) to the second Lead solar cell (102).

10. The method of claim 9 further comprising: Forming spacers (140) between at least two adjacent busbars (121, 122, ...) in the overlapping area (112) in order to support a force acting perpendicular to the main surfaces (101a, 101b).

11. The method according to claim 9 or claim 10, wherein the provision of a first solar cell (101) and the provision of a second solar cell (102) is carried out in such a way that at least part of the busbar (121, 122, ...) is continuously from of the first solar cell (101) to the second solar cell (102).