THIN-FILM PHOTOVOLTAIC MODULE

• US 20100131108A1
• Filed: 01/08/2010
• Published: 05/27/2010
• Est. Priority Date: 01/18/2008
• Status: Active Grant

• Current Assignee: Spectrum Solar, LLC
• Original Assignee: Tenksolar, Inc.
• Inventors: Meyer, Dallas W.
• Granted Patent: US 8,212,139 B2
• Time in Patent Office: Days
• US Class Current: 700/275
• CPC Class Codes: H01L 31/048 Encapsulation of modules
• CPC Class Codes: H01L 31/05 Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells electrodes H01L31/0224; electrical interconnection of thin film solar cells formed on a common substrate H01L31/046; particular structures for electrical interconnecting of adjacent thin film solar cells in the module H01L31/0465; electrical interconnection means specially adapted for electrically connecting two or more PV modules H02S40/36
• CPC Class Codes: H01L 31/0504 specially adapted for series or parallel connection of solar cells in a module
• CPC Class Codes: H01L 31/0508 the interconnection means having a particular shape
• CPC Class Codes: H01L 31/0547 comprising light concentrating means of the reflecting type, e.g. parabolic mirrors, concentrators using total internal reflection
• CPC Class Codes: H02S 40/36 characterised by special electrical interconnection means between two or more PV modules, e.g. electrical module-to-module connection
• CPC Class Codes: Y02E 10/52 PV systems with concentrators

Abstract

In some embodiments, a photovoltaic module includes an active layer, a top layer, and a bottom layer. The active layer includes a plurality of strips of thin-film PV material that are arranged spaced apart from and substantially parallel to each other. The top layer is disposed above the active layer and includes a substantially transparent film. The bottom layer is disposed below the active layer, the bottom layer including a conductive backsheet configured to form a current return path for the strips of thin-film PV material. The PV module further includes means for serially and redundantly interconnecting the strips of thin-film PV material together.

Claims

1. A photovoltaic module, comprising:

an active layer including a plurality of strips of thin-film photovoltaic material that are arranged spaced apart from and substantially parallel to each other, each of the plurality of strips being continuous substantially the entire length of the photovoltaic module;

a top layer disposed above the active layer, the top layer including a substantially transparent film;

means for serially and redundantly interconnecting the strips of thin-film photovoltaic material together; and

a bottom layer disposed below the active layer, the bottom layer including a conductive backsheet configured to form a current return path for the strips of thin-film photovoltaic material

2. The photovoltaic module of claim 1, wherein a length of each of the strips of thin-film photovoltaic material is in a range of 20 feet to 40 feet and an aspect ratio of the photovoltaic module is in a range of 6 to 50.

3. The photovoltaic module of claim 1, wherein the substantially transparent film has a thickness in a range of 15 microns to 300 microns, and wherein the substantially transparent film includes a weatherability film and a barrier layer film.

4. The photovoltaic module of claim 1, wherein the means for serially and redundantly interconnecting includes a plurality of top layer conductive strips laminated to a bottom surface of the top layer and interposed between the strips of thin-film photovoltaic material.

5. The photovoltaic module of claim 4, wherein the means for serially and redundantly interconnecting further includes at least one of:

a power collection macro grid intermittently formed on a bottom surface of the top layer, the bottom surface of the top layer being configured to contact an upper surface of each of the strips of thin-film photovoltaic material, wherein each area of the power collection macro grid includes a plurality of interconnected grid lines of conductive material, the plurality of interconnected grid lines of conductive material being between 50 microns to 200 microns wide and 50 microns to 200 microns deep, each area of the power collection macro grid configured to contact and collect power from an underlying strip of thin-film photovoltaic material;

or

a power collection nano grid intermittently formed on the bottom surface of the top layer, wherein each area of the power collection nano grid includes a plurality of conductive nano particles arranged in an interconnected network of conductive traces, each area of the power collection nano grid configured to contact and collect power from an underlying strip of thin-film photovoltaic material.

6. The photovoltaic module of claim 5, wherein each of the plurality of top layer conductive strips at least partially overlaps at least one of an adjacent area of the power collection macro or nano grid such that one lengthwise edge of each of the plurality of top layer conductive strips is connected to at least one of an adjacent area of the power collection macro or nano grid.

7. The photovoltaic module of claim 4, wherein the means for serially and redundantly interconnecting further includes a plurality of bottom layer conductive strips laminated to a top surface of the bottom layer, each of the plurality of bottom layer conductive strips being at least partially disposed beneath a corresponding one of the plurality of top layer conductive strips and an adjacent one of the plurality of strips of thin-film photovoltaic material, each strip of thin-film photovoltaic material including a substrate connected to a bottom layer conductive strip and a transparent conducting oxide connected to a top layer conductive strip such that the strips of thin-film photovoltaic material a serially and redundantly interconnected.

8. The photovoltaic module of claim 7, wherein each of the plurality of top layer conductive strips at least partially overlaps an adjacent one of the plurality of strips of thin-film photovoltaic material, a bottom surface of each top layer conductive strip directly contacting the transparent conducting oxide of an adjacent strip of thin-film photovoltaic material.

9. The photovoltaic module of claim 7, wherein the plurality of top and bottom layer conductive strips comprise metal, the photovoltaic module further comprising a visco-elastic material disposed between the plurality of bottom layer conductive strips and the plurality of top layer conductive strips, the plurality of top and bottom layer conductive strips and visco-elastic material forming a constrained layer damper.

10. The photovoltaic module of claim 4, wherein at least one of:

the plurality of top layer conductive strips have conductivity ranging from 10<sup>−

6</sup> to 10<sup>−

8</sup> ohm-meters;

the plurality of top layer conductive strips include at least one of aluminum, stainless steel, copper, tin, or non-stainless low carbon steel;

the plurality of top layer conductive strips include a coating of nickel, aluminum, copper, tin, silver, or strained layers of polyethylene terephthalate;

or

each of the plurality of top layer conductive strips is configured to be plastically deformed.

11. The photovoltaic module of claim 1, wherein:

the bottom layer includes a plurality of bottom layer conductive strips laminated to a top surface of the bottom layer;

each bottom layer conductive strip overlaps two corresponding adjacent strips of thin-film photovoltaic material;

an isolation material is disposed between the plurality of bottom layer conductive strips and plurality of strips of thin-film photovoltaic material in areas of overlap;

a first longitudinal edge of each bottom layer conductive strip is connected through at least one contact strip to a substrate on a bottom surface of one of the corresponding adjacent strips of thin-film photovoltaic material in the area of overlap of the first longitudinal edge;

the means for serially and redundantly interconnecting includes a plurality of gimbal strips laminated to a bottom surface of the top layer, each gimbal strip configured to discretely connect a second longitudinal edge of each bottom layer conductive strip to a transparent conducting oxide of the other one of the corresponding adjacent strips of thin-film photovoltaic material.

12. The photovoltaic module of claim 1, wherein:

the top layer includes a plurality of stitched contact strips configured to connect each of a plurality of bottom layer conductive strips to a transparent conducting oxide of an adjacent strip of thin-film photovoltaic material;

each stitched contact strip comprises a wire arranged in a stitch pattern, the wire having a diameter in a range of 12 microns to 75 microns;

each wire comprises at least one of copper, gold, aluminum, or tin; and

each stitched contact strip includes a plurality of contact points, at least some of the contact points configured to contact a bottom layer conductive strip and at least some of the contact points configured to contact the transparent conducting oxide of an adjacent strip of thin-film photovoltaic material.

13. The photovoltaic module of claim 1, wherein the top layer includes a plurality of stitched contact strips, a stitch pattern of each stitched contact strip variably encroaching over an underlying flexible strip of thin-film photovoltaic material along the length of the stitched contact strip.

14. The photovoltaic module of claim 1, wherein:

the bottom layer includes a plurality of bottom layer conductive strips laminated to a top surface of the bottom layer and at least partially aligned between the plurality of strips of thin-film photovoltaic material;

each bottom layer conductive strip overlaps an adjacent strip of thin-film photovoltaic material;

a conductive material is disposed between a top surface of each bottom layer conductive strip and a substrate on a bottom surface of each strip of thin-film photovoltaic material in areas of overlap; and

the conductive material comprises one or more of conductive adhesive, conductive epoxy, or conductive tape.

15. The photovoltaic module of claim 1, further comprising:

an electronic circuit layer connected between a first outer strip of thin-film photovoltaic material and the conductive backsheet; and

a substantially electrically insulating material disposed between the conductive backsheet and the plurality of strips of thin-film photovoltaic material;

wherein;

the electronic circuit layer is connected to a top surface of the first outer strip of thin-film photovoltaic material and the conductive backsheet is connected to a substrate on a bottom surface of a last outer strip of thin-film photovoltaic material;

or

the electronic circuit layer is connected to a substrate on a bottom surface of the first strip of thin-film photovoltaic material and the conductive backsheet is connected to a top surface of the last outer strip of thin-film photovoltaic material.

16. The photovoltaic module of claim 15, wherein the electronic circuit layer includes an input bus, a current return bus and a conditioned output bus, the photovoltaic module further comprising a plurality of redundant power conversion circuits connected to each other in parallel between the input bus, current return bus and the conditioned output bus.

17. The photovoltaic module of claim 16, wherein the electronic circuit layer is fabricated within and during fabrication of the photovoltaic module and wherein the redundant power conversion circuits are housed within discrete housings, the discrete housings within and redundant power conversion circuits being attached to the photovoltaic module after completion of photovoltaic module fabrication.

18. The photovoltaic module of claim 15, wherein the substantially electrically insulating material includes at least one of polyethylene terephthalate or poly methyl methacrylate.

19. The photovoltaic module of claim 1, wherein the conductive backsheet comprises less than three non-metal laminated films and wherein an exposed surface of the conductive backsheet is black and has an emissivity greater than 0.6.

20. The photovoltaic module of claim 1, wherein the conductive backsheet comprises an exposed electrical ground.

21. The photovoltaic module of claim 1, wherein lengths of the plurality of strips of thin-film photovoltaic material are substantially equal, widths of the plurality of strips of thin-film photovoltaic material are different from one strip to another, and the current output of each strip under uniform lighting conditions is substantially equal.

22. The photovoltaic module of claim 1, wherein the bottom layer and top layer extend beyond the edges of the plurality of strips of thin-film photovoltaic material.

23. A method of forming a longitudinally continuous photovoltaic module, comprising:

arranging a plurality of strips of thin-film photovoltaic material to be spaced apart from and substantially parallel to each other;

laminating a bottom layer to a first surface of the plurality of strips of thin-film photovoltaic material, the bottom layer including a plurality of bottom layer conductive strips;

laminating a top layer to a second surface of the plurality of strips of thin-film photovoltaic material, the second surface opposite the first surface, the top layer including a plurality of top layer conductive strips;

wherein laminating the bottom layer to the first surface and laminating the top layer to the second surface includes serially and redundantly interconnecting the plurality of strips of thin-film photovoltaic material together by connecting each one of the strips of thin-film photovoltaic material to a different one of the plurality of bottom layer conductive strips and a different one of the plurality of top layer conductive strips.

24. The method of claim 23, further comprising, cutting a sheet of thin-film photovoltaic material into the plurality of flexible strips.

25. The method of claim 24, wherein the sheet of thin-film photovoltaic material includes a transparent conducting oxide on the second surface, the method further comprising, prior to cutting the sheet of thin-film photovoltaic material into the strips of thin-film photovoltaic material, ablating the transparent conducting oxide from a region between each of the subsequently-formed strips of thin-film photovoltaic material, a width of each of the regions being in the range of 100 microns to 400 microns.

26. The method of claim 25, wherein:

ablating the transparent conducting oxide from a region between each of the subsequently-formed strips of thin-film photovoltaic material includes directing a first laser at the regions, the first laser configured to emit light having a wavelength between 400 nanometers and 10 nanometers; and

cutting the sheet of thin-film photovoltaic material into the strips of thin-film photovoltaic material includes directing a second laser at the regions, the second laser configured to emit light having a wavelength between 750 nanometers and 1400 nanometers.

27. The method of claim 25, further comprising, applying a protective layer to ablated regions of the transparent conducting oxide after cutting the sheet of thin-film photovoltaic material into the plurality of strips of thin-film photovoltaic material, the protective layer including at least one of dielectric, sealant or silicone.

28. The method of claim 23, further comprising one or more of:

forming an intermittent power collection macro grid on a first surface of the top layer, the first surface of the top layer being configured to contact the second surface of the strips of thin-film photovoltaic material;

or

forming an intermittent power collection nano grid on the first surface of the top layer.

29. The method of claim 28, wherein forming a power collection macro grid on the first surface of the top layer includes:

partially perforating the first surface of the top layer to form a plurality of interconnected grid lines in the first surface, wherein each of the plurality of interconnected grid lines is between 50 microns to 200 microns wide and 50 microns to 200 microns deep;

filling the plurality of interconnected grid lines with a conductive paste; and

curing the conductive past to drive off organic material from the paste.

30. The method of claim 23, wherein the top layer conductive strips are reflective, the method further comprising, forming regions of the photovoltaic module including the plurality of top layer conductive strips into concentrators.

31. The method of claim 30, wherein a cross-sectional shape and dimensions of each concentrator region depend on at least one of an installation angle and installation latitude of an installation site of the photovoltaic module.

32. The method of claim 31, wherein the concentrators are formed at the installation site.

33. The method of claim 30, further comprising mounting the photovoltaic module to a framing structure, the framing structure including one or more shaped supports having a first shape that is complementary to a second shape of the concentrators.

34. The method of claim 33, further comprising securing the photovoltaic module to the framing structure by securing one or more of the concentrators to the one or more shaped supports using at least one of a metal or plastic nail, a plastic-coated nail, a rubber-coated nail, a nail with a sealing head, a metal or insulating-coated screw, a screw with a sealing head, a clip, or other fastener.

35. The method of claim 23, further comprising forming a plurality of through holes in each of the plurality of top layer conductive strips at regular intervals prior to laminating the top layer to the second surface of the plurality of strips of thin-film photovoltaic material, the through holes being configured to receive fasteners for securing the photovoltaic module to a support structure at an installation site.

36. The method of claim 23, wherein the bottom layer includes a conductive backsheet, the method further comprising forming a plurality of through holes in the conductive backsheet at regular intervals prior to laminating the bottom layer to the first surface of the plurality of flexible strips, the through holes being configured to receive fasteners for securing the photovoltaic module to a support structure at an installation site.

37. The method of claim 23, wherein a visco-elastic material is disposed between the top layer conductive strips and the bottom layer conductive strips to form a constrained damper layer, the method further comprising mounting the photovoltaic module to a support structure, the support structure including a plurality of pieces arranged substantially normal to the length of the plurality of flexible strips, the plurality of pieces of the support structure being spaced on one foot to six foot centers.

38. The method of claim 23, further comprising:

outputting a laminated sheet including the plurality of flexible strips, the bottom layer and the top layer in a roll, the laminated sheet being 100 feet to 2000 feet in length; and

cutting the photovoltaic module to length from the rolled laminated sheet.

39. The method of claim 38, further comprising performing one or more of product testing and burn-in testing on the rolled laminated sheet.

40. A computer-readable storage medium having stored thereon, computer-executable instructions that, if executed by a computing device, cause the computing device to perform a method comprising:

receiving data indicating an installation angle for a photovoltaic module at an installation site, the photovoltaic module including a plurality of plastically deformable reflector regions and a plurality of longitudinally continuous strips of thin-film photovoltaic material;

receiving data indicating a direction the installation site faces;

receiving data indicating a latitude of the installation site;

receiving data indicating elastic and visco-elastic bend relaxation parameters for the photovoltaic module; and

determining a shape for the plurality of plastically deformable reflector regions based on the received data.

41. The computer-readable storage medium of claim 40, further comprising computer-executable instructions for causing a machine to plastically deform the plurality of plastically deformable reflector regions into the optimized shape.