Method For Fabricating A Curved Photovoltaic Module Including Adapted Positioning Of Photovoltaic Cells

Abstract

A method of fabricating a non-uniformly curved photovoltaic module including multiple photovoltaic cells forming a body part of a vehicle and having differently curved areas. The method includes determining a minimum allowable bending radius of the photovoltaic cells, analysing a curvature radius of one of the photovoltaic cells being assumed to be arranged at a positioning area within the photovoltaic module, with the curvature radius being analyzed for each of multiple positioning areas along a lateral extension of the photovoltaic module, arranging the photovoltaic cells in a curvature limited configuration in which none of the photovoltaic cells overlaps a highly bended area, the curvature radius of which being analyzed to be smaller than the minimum allowable bending radius, and fixing the photovoltaic cells in the curvature limited configuration within the photovoltaic module, thereby preventing excessive bending and resulting breaking or cracking of photovoltaic cells.

Claims

1. Method for fabricating a non-uniformly curved photovoltaic module comprising multiple photovoltaic cells, the method at least comprising: determining a minimum allowable bending radius r.sub.b of the photovoltaic cells, analyzing a curvature radius r.sub.c of one of the photovoltaic cells being assumed to being arranged at a positioning area within the photovoltaic module, wherein the curvature radius r.sub.c is analyzed for each of multiple positioning areas along a lateral extension of the photovoltaic module, arranging the photovoltaic cells in a curvature limited configuration in which none of the photovoltaic cells overlaps a highly bended area the curvature radius r.sub.c of which has been analyzed to be smaller than the minimum allowable bending radius r.sub.b for the photovoltaic cell, and fixing the photovoltaic cells in the curvature limited configuration within the photovoltaic module.

2. Method according to claim 1, wherein the curvature radius r.sub.c is analyzed for one of the photovoltaic cells being assumed to being arranged at the positioning area within the photovoltaic module upon the photovoltaic module being in its final geometry after completion of the fabrication method.

3. Method according to claim 2, wherein the curvature radius r.sub.c of the photovoltaic cell is analyzed by at least one of arrangement experiments, arrangement simulations and arrangement calculations performed for one of measuring, simulating and calculating, respectively, the curvature radius r.sub.c of the photovoltaic cell when being arranged at the positioning area.

4. Method according to claim 1, wherein the curvature radius r.sub.c is analyzed for one of the photovoltaic cells being assumed to being arranged at the positioning area within the photovoltaic module upon the photovoltaic module being deformed into a first temporary geometry during the fabrication method.

5. Method according to claim 4, wherein the curvature radius r.sub.c of the photovoltaic cell is analyzed by at least one of deformation experiments, deformation simulations and deformation calculations performed for one of measuring, simulating and calculating, respectively, the curvature radius r.sub.c of the photovoltaic cell when being arranged at the positioning area upon the photovoltaic cell being subjected to a deformation action, the deformation action occurring as a result of a fabrication procedure and temporarily deforming the curvature of the photovoltaic cell during the fabrication method.

6. Method to claim 1, wherein the curvature radius r.sub.c is analyzed for one of the photovoltaic cells being assumed to being arranged at the positioning area within the photovoltaic module upon the photovoltaic module being deformed into a second geometry resulting upon thermal expansion of the photovoltaic module upon the fabricated photovoltaic module being installed in an intended installation configuration and being subjected to predefined temperature variations.

7. Method according to claim 6, wherein the curvature radius r.sub.c of the photovoltaic cell is analyzed by at least one of expansion experiments, expansion simulations and expansion calculations performed for one of measuring, simulating and calculating, respectively, the curvature radius r.sub.c of the photovoltaic cell when being arranged at the positioning area upon the photovoltaic module being subjected to thermal expansion upon the fabricated photovoltaic module being installed in the intended installation configuration and being subjected to predefined temperature variations.

8. Method according to claim 1, wherein the minimum allowable bending radius r.sub.b of the photovoltaic cell is determined by at least one of bending experiments, bending simulations and bending calculations performed for one of measuring, simulating and calculating, respectively, the curvature radius of the photovoltaic cell upon being successively bent, the minimum allowable bending radius r.sub.b being determined as the curvature radius being established just before the photovoltaic cell breaks due to excessive bending.

9. Method to claim 1, wherein the photovoltaic cells are arranged on both opposite sides with regard to the highly bended area.

10. Method according to claim 1, wherein the photovoltaic cells are arranged at a lateral distance d from the highly bended area, the lateral distance d being larger than a predefined minimum distance.

11. Method according to claim 10, wherein the minimum distance d is predefined in dependence of the curvature radius at the highly bended area.

12. Method according to claim 1, wherein the photovoltaic cells included in PV module are wafer-based photovoltaic cells.

13. Method to claim 1, wherein the arranging and fixing of the photovoltaic cells include: arranging the photovoltaic cells on at least one polymeric foil in the curvature limited configuration, fixing the photovoltaic cells on the polymeric foil in the curvature limited configuration thereby forming a photovoltaic label and preparing a carrier structure for carrying the photovoltaic label wherein the carrier structure is prepared with a polymer being in a moldable condition such that the polymer forms a positive substance jointing with the polymeric foil upon solidifying of the polymer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In the following, advantageous embodiments of the invention will be described with reference to the enclosed drawing. However, neither the drawing nor the description shall be interpreted as limiting the invention.

[0068] FIG. 1 shows a perspective view of a PV module forming a mudguard of a car body.

[0069] FIGS. 2 (a), (b) show a side views onto a PV cell in a planar configuration and in a curved configuration.

[0070] FIG. 3 shows a cross-sectional view along the line A-A indicated in FIG. 1.

[0071] FIG. 4 visualized arranging PV cells in a curvature limited configuration upon fabricating a curved PV module in accordance with an embodiment of the present invention.

[0072] FIG. 5 shows a cross-section through a moulding tool upon fabricating a curved PV module in accordance with an embodiment of the present invention.

[0073] The figures are only schematic and not to scale. Same reference signs refer to same or similar features.

DESCRIPTION OF ADVANTAGEOUS EMBODIMENTS

[0074] FIG. 1 visualises a contour of a non-uniformly curved PV module 1 forming a body part of a vehicle. In the specific example, the PV module 1 forms a mudguard of a car. Therein, the PV module 1 comprises flat or slightly curved areas 3 as well as significantly curved areas 5. The PV module 1 shall comprise a multiplicity of PV cells 7 (only a few of them being visualised with dotted lines as examples in FIG. 1). Accordingly, the PV cells 7 are integrally included in the vehicle body part.

[0075] Preferably, the PV cells 7 shall be wafer-based silicon PV cells. Such wafer-based PV cells 7 are generally rigid and brittle. With no forces being applied to such PV cells 7, they generally have a plate-like, planar shape as shown in FIG. 2(a).

[0076] For fabricating the non-uniformly curved PV module 1, the PV cells 7 have to be included into the PV module 1 in a curved configuration.

[0077] Accordingly, in a fabrication method as proposed herein, a minimum allowable bending radius r.sub.b of the PV cells 7 has to be determined. For such purpose, bending experiments, bending simulations and/or bending calculations may be performed. Therein, real or virtual bending forces 9, respectively, may be applied to the PV cell 7 in order to bend the PV cell 7. Preferably, such forces 9 are applied in a distributed manner along a lateral extension of the PV cell 7 such that the PV cell 7 bends homogeneously. In the bending experiments, simulations and/or calculations, the minimum allowable bending radius r.sub.b is determined to be the radius down to which the PV cell 7 may be bent at a maximum, i.e. just before the PV cell 7 is irreversibly damaged by breaking or cracking.

[0078] Furthermore, a curvature radius r.sub.c of the PV cell 7 upon being included in the PV module 1 has to be analysed, as visualised in FIG. 3. In such analysis, it is assumed that the PV cell 7 is arranged at a positioning area 11 within the PV module 1. Curvature radii r.sub.c1, r.sub.c2, r.sub.c3, r.sub.c4, etc. may be analysed for each of multiple positioning areas 11 along the lateral extension of the PV module 1.

[0079] For such analysis, arrangement experiments, simulations and/or calculations may be performed. Therein, in an arrangement experiment, a real PV cell 7 may be arranged at a positioning area 11 within or on top of a surface of for example a prototype of a PV module 1 such as to assume a curvature with which the PV cell 7 would be bent upon being included in the non-planar PV module 1 upon completion of the fabrication of such PV module 1. Alternatively, in arrangement simulations or calculations, a virtual PV cell 7 may be virtually arranged at a positioning area 11 within a virtual model of the PV module 1 such as to assume a curvature with which the PV cell 7 would be bent upon being included in the non-planar PV module 1 upon completion of the fabrication of such PV module 1. In the arrangement experiments, simulations and/or calculations, the curvature radii r.sub.cx may be measured, simulated or calculated, respectively, for each of various positioning areas 11 within the PV module 1.

[0080] As an alternative or additionally to the arrangements experiments, simulations and/or calculations, the curvature radius of the PV cell 7 may be analysed by deformation experiments, deformation simulations and/or deformation calculations. Therein, the PV cell may be arranged at various positioning areas 11 in a similar manner as described above. However, the PV module 1 is not assumed to be in its final geometry, i.e. in a shape which the PV module 1 assumes directly after completion of the fabrication method. Instead, it is assumed that the PV module 1 is deformed into a first temporary geometry while being fabricated. Such deformed geometry may result from forces applied to the PV module 1 and to the PV cells 7 included therein during the fabrication method. Such forces may apply for example during injection moulding for forming a carrier structure for the PV module 1. Upon deformation of the PV module 1 due to such forces, the PV cell 7 being arranged at a positioning area 11 may be bent to a smaller curvature radius r.sub.c than it is the case for the PV module 1 being in its final geometry after completion of the fabrication method.

[0081] As a further alternative or additionally, expansion experiments, expansion simulations and/or expansion calculations may be used for analysing the curvature radius of the PV cells 7. Therein, the PV module 1 is again assumed to not being in its final geometry but in a geometry resulting upon thermal expansion of the PV module 1 when the PV module 1 is installed in an intended installation configuration and is subjected to predetermined temperature variations.

[0082] In the exemplary embodiment described herein, this may mean that the mudguard-shaped PV module 1 is connected to a chassis of a vehicle at various connection positions. Therein, it is then assumed that the PV module 1 may deform due to thermal expansion thereof and the resulting deformations may influence the curvature radius r.sub.c of the PV cells 7 included in the PV module 1.

[0083] Upon having determined the minimum allowable bending radius r.sub.b of the PV cells 7 as well as having analysed the curvature radius r.sub.c of the PV cell 7 for each of multiple positioning areas 11 in the PV module 1 in a state as fabricated, during fabrication and/or after installation, the PV cells 7 are then arranged in a curvature limited configuration.

[0084] An example of such curvature limited configuration is shown in FIG. 4. Therein, the PV cells 7 are arranged such that none of them overlaps a highly bended area 13 at which the curvature radius r.sub.c of the PV cell 7 upon being arranged in such highly bended area 13 would be smaller than the minimum allowable bending radius r.sub.b. In other words, the PV cells 7 are arranged in the curvature limited configuration such that all PV cells 7 are completely outside the highly bended area. Accordingly, all PV cells 7 included in the PV module 1 in such curvature limited configuration will have a curvature radius r.sub.c > r.sub.b. PV cells 7 may be arranged at both opposing sides with regard to the highly bended area 13. As an additional precaution, the PV cells 7 may be arranged at a lateral distance d from the highly bended area 13. As a result of including the PV cells 7 in the PV module 1 in such curvature limited configuration, a risk of breaking or cracking of PV cells 7 is minimised.

[0085] In order to arrange the PV cells 7 in the curvature limited configuration and then fix the PV cells 7 in this configuration within the PV module 1, a specific procedure is proposed herein, such procedure resembling to an in-mould labelling procedure. Therein, the PV cells 7 are first arranged on a polymeric foil 15 or, preferably, between two polymeric foils 15. A stack including the one or two polymeric foils 15 and the PV cells 7 may then be laminated to form a PV label 17. In such PV label 17, the PV cells 7 are already fixed in their positions in the curvature limited configuration. However, the PV label 17 is not self-supporting and not stable enough for forming a PV module 1. Accordingly, a carrier structure 29 for carrying the PV label 17 is then prepared.

[0086] For such purpose, as schematically visualised in FIG. 5, the PV label 17 may be inserted into an injection moulding tool 19. Such tool 19 comprises a cavity 21, at least one inlet 25 to the cavity 21 and at least one outlet 27 from the cavity 21. A shape of the cavity 21 substantially corresponds to an intended geometry of the non-uniformly curved PV module 1. The PV label 17 is preferably arranged at an outer surface defining one side of the cavity 21. Subsequently, a polymer 23 is introduced into the cavity 21. Therein, the polymer 23 is brought to a mouldable condition. For example, the polymer 23 is heated to an elevated temperature being higher than a glass transition temperature of the polymer 23. Accordingly, the polymer 23, upon being introduced through the inlet 25, will distribute throughout the cavity 21 and will contact an exposed surface of the PV label 17. Upon subsequently cooling down the polymer 23, the polymer 23 will solidify and forms the carrier structure 29 while simultaneously forming a positive substance jointing with the polymeric foil 15 of the PV label 17. The final product of such IML-like procedure may be a PV module 1 in which the PV cells 7 are arranged in the curvature limited configuration.

[0087] While the PV module 1 may be non-uniformly curved and may include one or more highly bended areas 15, the arrangement of the PV cells 7 is specifically adapted such that PV cells 7 are only included in areas outside such highly bended areas 15. Accordingly, none of the PV cells is excessively bent and breaking or cracking of PV cells 7 prevented.

[0088] Finally, it should be noted that the term “comprising” does not exclude other elements or steps and the “a” or “an” does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

TABLE-US-00001 list of reference numerals: 1 PV module 3 flat or slightly curved area 5 significantly curved area 7 PV cell 9 bending forces 11 positioning area 13 highly bended area 15 polymeric foil 17 PV label 19 moulding tool 21 cavity 23 polymer 25 inlet 27 outlet 29 carrier structure