WO2008125340A2

WO2008125340A2 - Solar cell module

Info

Publication number: WO2008125340A2
Application number: PCT/EP2008/003021
Authority: WO
Inventors: Michael Schlipf; Katja Widmann
Original assignee: Elringklinger Ag
Priority date: 2007-04-16
Filing date: 2008-04-16
Publication date: 2008-10-23
Also published as: WO2008125340A3; DE102007018711A8; DE102007018711A1

Abstract

The aim of the invention is to produce solar cell modules which allow the production cost of solar panels to be reduced. Said aim is achieved by a solar cell module comprising several solar cells and a common frame for the same. The frame has a bottom and a top frame part with webs. The solar cells of the module are arranged substantially on a single plane and are disposed at a distance from one another between the top and bottom frame parts. In the mounted state of the module, the webs are located between adjacent solar cells. The frame parts are made of a thermoplastic, fully fluorinated synthetic material and are connected to form an integral joint such that all edges of the solar cells of the module are entirely surrounded in a liquid-tight manner by the frame parts and the webs thereof.

Description

solar cell module

The invention relates to a solar cell module and solar cell panels, which integrate a plurality of solar cell modules and interconnected.

Traditionally, individual cells are assembled into solar cell modules with individual frames of elastomeric material, such as FPM or EPDM, and the framed individual framed solar cells are then integrated into a solar cell panel. The frames made of elastomeric material are usually constructed of two frame parts, which are connected to each other in a press fit and hold the individual solar cell between them. The frames cover the edges of the solar cells sealingly and protect them and the contact points for electrical connections from acting liquids that flow around the modules with the cells during operation of the panels.

Alternatively, solar cells were fully embedded in EVA films, with the EVA material also completely covering the solar cell surfaces, the edges as well as the electrical contact points.

The solar panels are usually designed for outdoor use and are therefore exposed to sunlight and other weather conditions, especially extreme temperature fluctuations.

The lifetimes of the solar cell panels are currently given as 20 years or more, in which the protective effect for the solar cells must be preserved.

The frames or the foils must not only protect the solar cells permanently against moisture or liquid access, but they must also be dimensioned so that at very fluctuating temperatures the occurring different thermal expansions of the solar cell on the one hand and the Rähmchenmaterials other hand taken into account.

In this case, a coverage of the edges of the solar cells should be as low as possible in order to expose an optimal surface area of the solar cells directly to sunlight and thus to be able to use for the photovoltaic.

The solar cells are provided with electrical connections which are led out of each individual frame and then interconnected in the solar cell panel.

In this type of conventional production of solar panels, a relatively large amount of work is necessary, which has a significant impact on the cost of manufacturing the solar panels.

Object of the present invention is to propose solar cell modules with which a more cost-effective production of solar panels is possible.

This object is achieved by a solar cell module, as defined in claim 1.

The solar cell modules according to the invention reduce the assembly effort in the manufacture of the panels considerably, since the number of components to be handled is significantly reduced by the integration of a plurality of solar cells in a module.

The integration of multiple solar cells in a module also allows a reduction of the wiring effort in the manufacture of the panels by the solar cells of a module internally, ie within the module, can be interconnected and the module requires only two electrical connections then. The number of cable bushings in the frame parts is correspondingly lower, which also has an advantageous effect on the secure shielding of the edges of the solar cells from the surroundings. Preferably, five or more solar cells are integrated into a module according to the invention.

For the integration of several solar cells within a module according to the invention, a single-line arrangement of the solar cells is particularly suitable.

Furthermore, the cohesive connection of the frame parts provides a considerably greater security for the sealing of the solar cell edges and their durability than the compression of Elastomermaterialrähmchen allows.

Unlike the laminated with cells cells, the surface of the solar cell remains uncovered, so that one of the aging effects of the modules, which was due to a reduction in the transparency of the laminating films, completely eliminated.

The production of frame parts, which meets the above requirements, is not possible with the usual elastomer materials. Moreover, the fully fluorinated thermoplastics used according to the invention also have a lower tendency to embrittlement and are in particular equipped with a considerably better temperature, weathering and chemical resistance.

Due to their thermoplastic properties, the plastic materials used in the invention can also be processed with a complex shape.

In this way it is very easy to form adjusting means in the frame parts which allow an exact positioning of the solar cells within the module. The adjusting means are preferably provided on at least one of the frame parts and comprise, for example, projections and / or recesses. In a particularly preferred embodiment, both frame parts following the edge of each solar cell following recesses. This can be achieved that the two frame parts are aligned by the solar cells positioned therebetween. In addition, here offers the opportunity to form the two frame parts identical, so that both frame parts can be manufactured with a single tool.

The excellent dielectric properties, in particular the relative dielectric constant and the damping coefficient, are also advantageous in the case of the plastic materials to be used according to the invention.

Preferably, the solar cells of a module are electrically interconnected within the frame, i. the electrical contact points of the individual solar cells and the electrical connection lines are covered and protected by the frame parts. In particular, the serial electrical interconnection of the cells lends itself here. The module itself with its plurality of solar cells requires only two, the frame material penetrating connections must be interconnected in the manufacture of the panels to the terminals of other modules.

In the context of the present invention, thermoplastic, fully fluorinated plastics are to be understood as meaning plastics which are thermoplastically processable in the conventional sense, i. form a melt that has a viscosity that allows standard melt processing techniques. Such plastics have a non-zero melt index (ASTM D1238-88).

These include co-polymers of tetrafluoroethylene (TFE) with different co-monomers and co-monomer contents, which are known, for example, as FEP, MFA, PFA or ^Teflon® AF.

A newer type of TFE co-polymer is described in the published patent applications WO 00/08071, WO 01/60911 and WO 03/078481 and is available on the market the brand Moldflon ^® available with co-monomer contents <3 mol%. More preferably, the proportion of the co-monomer is less than 1 mol%.

Preferred co-monomers are selected from hexafluoropropylene, perfluoro (alkyl vinyl ether), perfluoro (2,2-dimethyl-l, 3-dioxoles) and chlorotrifluoroethylene.

The Moldflon ^® materials have a over a very wide temperature range, ie, in particular from 0 ⁰ C to 300 ⁰ C, the highest storage modulus E ¹ as compared with PTFE, PFA and FEP, as measured by the Dynamic Mechanical Thermal Analysis DMTA.

Further, the mechanical properties of the Moldflon ^® -Materials remain to get close to the melting point.

The water absorption is very low, so that the frame parts can be realized as precision components, which remain dimensionally stable even in contact with aqueous liquids.

The following Table 1 gives an overview of the most important properties of various examples of polymers to be used according to the invention. It also contains the corresponding data for conventional PTFE for comparison.

As an alternative to co-polymers of TFE, polymer blends with PTFE as a major component and other thermoplastic polymers can be used. Examples can be found in WO 00/08071. Other examples are the materials described in EP 1 077 230 A1.

Table 1 Physical properties of fully fluorinated plastics

The cohesive connection can be done for example by gluing. However, in some cases this does not lead to the desired safety, in particular with regard to the desired long service life of the solar cell modules.

Cheaper in this regard, the welding of the frame parts. However, this is particularly the case with the preferred the fully fluorinated Kunststoffmateiϊalen a challenge, since these materials have melting points, which are far beyond the maximum ambient temperatures allowed for solar cells.

Particularly preferred solar modules therefore have one or more resistance heating elements integrated in the frame. Here, with a short current pulse, a sufficient amount of energy for a reliably sealing weld can be entered into the regions of the frame parts to be welded, without a temperature increase affecting the solar cells being produced at the edges of the solar cells encompassed by the frame parts. This can be realized even if the frame parts are manufactured with a very small tolerance with respect to the dimensions of the solar modules and therefore the edges of the solar cells essentially rest directly against the plastic material of the frame parts.

The resistance heating elements may remain permanently in the solar cell module.

The resistance heating element can be formed as a wire frame part or sheet metal frame part, which essentially follows the contours of a frame part together with its webs. Such a heating element is simply inserted in the production of the module between the two frame parts and then welded into the module or its frame as a lost part.

Alternatively, the resistance heating element may be multi-part, wherein the heating element may then have recesses at the locations where electrical lines transverse to the frame parts and their webs to a physical and electrical contact of the heating element with these lines and a direct energy input into these module parts safely avoid.

Other preferred methods for welding the frame parts include heating the frame parts to superimposed surface areas to above the melting point of the plastic material and subsequent joining at a predetermined joining pressure.

It is advantageous here that no components which are not inherent in the module remain in the finished module. Furthermore, some of these methods are simpler and less expensive.

The heating of the frame parts, for example, with a heating element, also called heating mirror, carried out in physical contact. The mirror temperature so called is selected here at the above Moldflon ^® materials at about 360 ⁰ C.

A proofing time of approx. 30 sec at a joining pressure of approx. 2.5 N / mm ² already provides satisfactory results. Temperatures above 400 ^° C should be avoided as they could lead to the release of harmful substances.

Another option for heating the frame parts is a hot gas welding system. With flue gas temperatures of about 1000 ⁰ C in the combustion space, heating times of about 12 sec, and a bonding pressure of about 3 N / mm ^2, satisfactory results are achieved at Moldflon ^® materials. The distance between the frame part or its surface to be heated to the hot gas welding device is chosen so that the temperature at the frame part surface is about 400 ⁰ C or less.

In addition, infrared radiation can also be used to heat the frame part surface, with long-wave infrared radiation in particular being preferred here.

The invention further relates to a method for producing the solar cell modules according to the invention.

The method according to the invention is characterized by the steps: an upper and a lower frame part made of a fully fluorinated plastic material are provided, which are provided with receptacles for a plurality of solar cells; Positioning the solar cells in the receptacles of a frame part;

Interconnecting the solar cells;

Positioning the second frame part on the one, the solar cell receiving frame part; and cohesively connecting the two frame parts at substantially the entire edge of each solar cell of the module.

The frame parts for use in the method according to the invention can be produced in a variety of methods, wherein in the case of simple contours of the frame parts they can be punched out of a sheet material.

For more complicated geometries, either the frame parts punched out of surface materials can be machined or else a machining operation is used for the entire production of the frame parts.

A particularly preferred method of production is in the injection molding process, since geometries with a complex structure are also available in one production step.

The solar cells to be processed in the process may either be individually contacted and provided with separate connection cables or, preferably, the plurality of solar cells used within a module are interconnected and electrically connected within the module. A cohesive connection of the frame parts can be achieved for example by gluing, as already mentioned above.

Preferably, with a view to greater safety, the welding of the frame parts, as also detailed above.

According to a preferred method, the welding of the frame parts can take place by means of resistance heating elements which are or can remain in the frame as an integral part. The resistance heating elements are formed so that they extend substantially over all the areas of the frame parts to be welded together, but preferably have recesses at the points at which electrical connections between the individual solar cells are made or connection cables from the solar cells through the frame step outside.

Preferably, the resistance heating elements comprise a sheet metal frame part, which essentially reproduces the weld seams to be produced and which is inserted between the two frame parts when the second frame part is positioned. To produce the welded connection, the sheet metal component then only has to be contacted electrically, which is preferably accomplished with electrical connections already provided in the frame.

Alternatively, it is conceivable to incorporate the resistance heating elements into one or both frame parts, for example in the form of resistance wires, in particular to pour them into the injection molding process as inserts.

Other preferred methods for cohesive bonding of the frame parts have already been described above, so that reference may be made to these statements.

These and other advantages of the invention are explained in more detail below with reference to the drawings. They show in detail:

Figure 1: A perspective view of an assembled solar cell module according to the invention;

Figure 2: exploded view of the module of Fig. 1;

Figure 3 is a plan view of a frame part of the module of Figure 1;

FIG. 4 shows a sectional view through a solar cell module according to the invention along line 4-4 in FIG. 1 before the welding of the frame parts; and

FIG. 5 shows the sectional view of FIG. 4 after welding

Frame parts of the module of FIG. 1.

1 shows a perspective view of a solar cell module 10 according to the invention with a frame 12 which is composed of two frame parts, an upper frame part 14 and a lower frame part 16. In window-like openings 20 of the frame 12 solar cells 18 are arranged. The openings 20 are separated by webs 22 from each other.

The solar cells 18 are electrically connected via the two terminals 24 to the environment and otherwise completely surrounded and protected at its edge regions by the material of the frame parts 14 and 16 and their webs 22.

At the respective terminal end edges of the frame 12 Heizleiteranschlüsse 26 exit. Their function will be explained in more detail below with reference to the drawings 2 to 5. FIG. 2 shows the solar cell module 10 in an exploded view. The individual parts of the module 10 are arranged here as it corresponds to the manufacturing process for the production of the complete module 10 approximately.

On the lower frame part 16, a heating element 28 is placed, which essentially follows the contours of the frame part 16 with its webs 20 dividing the windows 20 from each other. The width of the individual parts of the Heizleiterelements 28 are compared to the width of the parts of the lower frame member 16 and its webs 22 is kept slightly narrower, so that on both sides of the individual parts of the Heizleiterelements 28, the material of the lower frame member 16 remains uncovered. The frame part 16 is preferably provided on its upper side with a recessed surface area 30 (cf., FIG. 3) into which the heating conductor element 28 can be inserted.

The outer parts of the lower frame part 16 and the webs 22 which delimit the windows 20 include groove-like recesses 34 and 32, respectively, which receive electrical leads which serve to connect the solar cell modules, i. in particular the connection lines 24 and the electrical lines 36, which connect the solar cells 18 with each other. For the heat conductor connections 26 to be mounted on the front side, a groove 38 is likewise provided on the end regions of the frame parts 16, which grooves receive the heating conductor connections 26.

The Heizleiterelement 28 may be formed in several parts (not shown) and then has in the region of the grooves 32 and 34 interruptions, so that a sufficient distance between the Heizleiterelement 28 and the electrical leads 24 and 36 is ensured. This also avoids a thermal bridge between the heating element 28 and the electrical lines 24 and 36, as well as the solar cells 18 directly connected thereto. In the case of multi-part heating elements, a plurality of connecting line pairs 26 are then required.

This can be of particular importance, since the welding of the two frame parts 14 and 16 temperatures depending on the plastic material up to 300 ⁰ C or more, temperatures that must be avoided for the solar cells in the short term absolutely.

The frame parts 14 and 16 have at their window-like openings 20 all-round projections 40 which form a receptacle for a solar cell 18 with the frame members 16 and 14 and their webs 22 and position this exactly predetermined position in the module.

The depth of the receptacles 40 formed for the solar cells is preferably dimensioned such that they can accommodate approximately half the thickness of the solar cells 18, so that on the positioned in the lower frame member 16 solar cells 18 still aufzustegende upper frame member 14 by the outer contours the solar cell 18 is positioned in an exact manner.

As soon as the frame part 14 has been placed on the solar cells 18 already containing the solar cells 18, a configuration of the frames and the heating conductor element 28 accommodated therebetween results, as shown in the sectional representation of FIG. Thereafter, the frame members 14 and 16 lie with their outer edges 41 directly on each other and hold between them in the recesses 30, the heating element 28. The frame parts 14 and 16 do not touch with their facing surfaces on the windows 20 facing areas and form there in the state shown in Figure 4 still a cavity 42. If, in the last production step, a short current impulse is applied by the heating conductor element 28, the heating conductor element 28 heats up to a temperature above the melting point of the plastic material of the frame parts 14 and 16 and leads to a fusion of the frame parts 14 and 16 both on their outer, directly adjacent to each other Areas 46 and 44, where previously the cavity 42 was present (see Fig. 5).

Thus, all side edges of the heating element 28 are connected by the plastic material of the frame parts 14 and 16 cohesively and close this from the environment. At the same time, the side edges of the Solar cells 18 continuously surrounded by the two frame parts 14 and 16 and their webs 22 and protected. The partially corrosive liquids flowing around the solar cell modules in the assembled state of a panel now only have contact with the surfaces of the solar cells within the areas defined by the windows 20 and can no longer reach the side edges of the solar cells 18.

Due to the inventive selection of plastic materials for the production of the frame parts 14 and 16, namely fully fluorinated thermoplastics, not only ensures that a close concern of these frame parts 14 and 16 takes place at the edges of the solar cells 18 and sealingly seals them, but also ensures the selection of materials in that this tightness is maintained during the lifetime of the solar cells, ie for 20 years or more. This is particularly true for the plastics from Moldflon ^® type.

In cases in which the frame parts 14 and 16 are connected to each other by other methods, eliminating the Heizleiterelemente 28 and their connections 26. The grooves in the frame parts, which serve to accommodate the Heizleiterelemente, can then be replaced by non-return surface areas.

Alternative methods are in particular the heating of the frame parts in direct physical contact with so-called heating mirrors, the hot gas welding or the IR heating of the contact surfaces to be joined frame parts. Thereafter, the frame parts are pressed together under a predetermined joining pressure while materially connected.

Claims

claims

A solar cell module comprising a plurality of solar cells and a common frame therefor, wherein the frame comprises a lower and an upper frame part with webs, wherein the solar cells of the module are arranged substantially in a plane and spaced from each other between the upper and lower frame parts, wherein the webs are arranged in the assembled state of the module between adjacent solar cells, and wherein the frame parts made of a thermoplastic, fully fluorinated plastic material and are materially connected to each other such that the solar cells of the module are completely and liquid-tight surrounded at all edges of the frame members and their webs ,

2. Solar cell module according to claim 1, characterized in that at least one of the frame parts comprises adjusting means by means of which the solar cells are adjustably inserted into the frame.

3. Module according to claim 2, characterized in that the adjusting means comprise projections and / or recesses.

4. Module according to one of claims 1 to 3, characterized in that the solar cells are arranged in a row.

5. Module according to claim 4, characterized in that the solar cells are connected in series with each other electrically.

6. Module according to one of claims 1 to 5, characterized in that a first solar cell is provided with a first passing through the frame outward terminal and that a further, last solar cell is provided with a further passing through the frame outward connection, the solar cells except the first and the last solar cell within the frame of the module are electrically connected to each other without outward-facing terminals.

7. Module according to one of the preceding claims, characterized in that the thermoplastic, fully fluorinated plastic material is a thermoplastically processable PTFE material.

8. Module according to claim 7, characterized in that the thermoplastic PTFE material is a TFE copolymer, wherein the co-monomer content is preferably 3.5 mol% or less, in particular less than 3 mol%, more preferably less than 1 mole%.

9. Module according to claim 8, characterized in that the co-monomer is selected from hexafluoropropylene, perfluoro (alkyl vinyl ether), perfluoro (2,2-dimethyl-l, 3-dioxoles) and chlorotrifluoromethylene.

10. Module according to one of claims 1 to 7, characterized in that the PTFE material is a polymer mixture comprising PTFE and a thermoplastically processable plastic.

11. Module according to one of the preceding claims, characterized in that the frame parts are injection molded components.

12. Module according to one of the preceding claims, characterized in that the frame contains in the cohesively joined regions resistance heating elements.

13. A method for producing a module according to one of claims 1 to 12, characterized in that an upper and a lower frame part, made of a fully fluorinated plastic material, are provided, which are provided with receptacles for a plurality of solar cells; Positioning the solar cells in the receptacles of a frame part;

Interconnecting the solar cells;

14. The method according to claim 13, characterized in that when providing the frame parts they are punched out of a sheet material.

15. The method according to claim 13 or 14, characterized in that the frame parts are obtained by means of a machining process.

16. The method according to claim 13, characterized in that the frame parts are produced by injection molding.

17. The method according to any one of claims 13 to 16, characterized in that the interconnection of the solar cells comprises contacting them with separate connection cables per solar cell.

18. The method according to any one of claims 13 to 16, characterized in that the interconnection of the solar cells comprises an electrical connection of the solar cells within the module.

19. The method according to any one of claims 13 to 18, characterized in that the cohesive connection of the frame parts comprises a welding of the frame parts.

20. The method according to claim 19, characterized in that the welding takes place by means of resistance heating elements.

21. The method according to claim 19, characterized in that the resistance heating elements are inserted during the positioning of the second frame part between the two frame parts.

22. The method according to claim 20, characterized in that the resistance heating elements are incorporated in one or both frame parts.

23. A solar cell panel comprising a housing and a plurality of the solar cell modules according to one of claims 1 to 12.