METHOD OF MANUFACTURING PHOTOVOLTAIC (PV) ENHANCEMENT FILMS

• US 20100181014A1
• Filed: 05/06/2009
• Published: 07/22/2010
• Est. Priority Date: 01/16/2009
• Status: Active Grant

• Current Assignee: GLTFuture, LLC
• Original Assignee: Genie Lens Technologies LLC
• Inventors: Lange, Howard G., Weiss, Seth, Raymond, Mark A.
• Granted Patent: US 8,048,250 B2
• Time in Patent Office: Days
• US Class Current: 156/209
• CPC Class Codes: B29C 2035/0827 using UV radiation
• CPC Class Codes: B29C 2035/0877 using electron radiation, e.g. beta-rays
• CPC Class Codes: B29C 59/04 using rollers or endless belts
• CPC Class Codes: F24S 23/10 Prisms
• CPC Class Codes: F24S 23/31 having discontinuous faces, e.g. Fresnel lenses
• CPC Class Codes: G02B 17/086 wherein the system is made of a single block of optical material, e.g. solid catadioptric systems
• CPC Class Codes: G02B 5/003 Light absorbing elements
• 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: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y02E 10/52 PV systems with concentrators
• CPC Class Codes: Y10T 156/1018 Subsequent to assembly of laminae
• CPC Class Codes: Y10T 156/1023 Surface deformation only [e.g., embossing]

Abstract

A method for manufacturing a photovoltaic (PV) enhancement film. The method includes providing an extrusion device with an embossing roller engraved to have a pattern corresponding to a set of absorption enhancement structures. The method includes feeding a web of substantially transparent material, such as an UV-stabilized blend of polycarbonate or acrylic. The method includes rolling the embossing roller against a first side of the web to form the absorption enhancement structures. The absorption enhancement structures each include a light receiving surface that directs at least a portion of light that passes through a second side of the web toward the first side back toward the second side (e.g., the structures may be configured to provide total internal reflection when applied to a PV device). The structures refract incident light to provide an average path length ratio of greater than about 1.10 in the PV device.

Claims

1. A method of manufacturing a photovoltaic (PV) enhancement film, comprising:

providing an extrusion device comprising an embossing roller with a surface engraved with a contoured pattern corresponding to a plurality of absorption enhancement structures;

feeding a web of substantially transparent material at an extrusion temperature to the extrusion device; and

rolling the embossing roller against a first side of the web to form the plurality of absorption enhancement structures, wherein the absorption enhancement structures each comprise a light receiving surface that directs at least a portion of light that passes through a second side of the web toward the first side back toward the second side, wherein each of the absorption enhancement structures comprises an elongated body including at least two sides angled inward, whereby the absorption enhancement structures extend outward from a substrate provided by the web of substantially transparent material.

2. The method of claim 1, wherein the light receiving surface refracts incident light striking the first side to provide an average path length ratio of greater than about 1.10 when the embossed web is applied over a layer of PV material over a range of incidence angles.

3. The method of claim 2, wherein the average path length ratio is determined as an average of a plurality of path length ratios determined within the range of incidence angles and each of the path length ratios being a path length of the refracted incident light traveling through the PV material after passing through the PV enhancement film compared with a path length of the incident light traveling through the PV material in an absence of the PV enhancement film.

4. The method of claim 3, wherein the plurality of path length ratios is determined based on ray tracings performed at a plurality of angles within the range of incidence angles.

5. The method of claim 4, wherein the range of incidence angles is a range of angles selected from the range of negative 80 degrees to positive 80 degrees as measured from an orthogonal plane passing through a light-receiving surface of the PV material.

6. The method of claim 4, wherein the range of incidence angles is a range of angles selected from the range of negative 20 degrees to positive 20 degrees as measured from an orthogonal plane passing through a light-receiving surface of the PV material.

8. The method of claim 1, wherein each of the absorption enhancement structures has a triangular cross section when taken along a plane passing orthogonal to a longitudinal axis and wherein the sides are angled inward at angles of less than about 60 degrees.

9. The method of claim 8, wherein adjacent ones of the absorption enhancement structures have differing heights as measured from the second side to a peak of the triangular cross section of the absorption enhancement structures.

10. The method of claim 1, wherein each of the absorption enhancement structures comprises three interconnected sides including two sides angled inward at angles of less than about 60 degrees and an upper planar side disposed between the two angled sides that is substantially parallel to the light-receiving surface.

14. The method of claim 1, wherein each of the absorption enhancement structures has a base and a height less than about 10 mils in magnitude.

15. The method of claim 1, further comprising cooling the embossed web, applying an adhesive to the second side, and cutting the embossed web into a plurality of PV enhancement films each with a predefined length and width.

16. The method of claim 1, wherein the web material comprises polycarbonate or acrylic, wherein the embossed web has a thickness of less than about 30 mils, wherein the extrusion temperature is at least about 300°

F., and wherein the embossing roller is chilled to a temperature below ambient.

29. The method of claim 1, wherein the elongate bodies extend across the first side of the web in a parallel manner and adjacent ones of the bodies have spaced apart facets defining a valley there between devoid of the substantially transparent material.

7. (canceled)

11. (canceled)

12. (canceled)

13. (canceled)

17. A method of fabricating a photovoltaic apparatus with enhanced energy absorption, comprising:

providing a layer of photovoltaic (PV) material that is positioned under a protective layer of substantially transparent material, wherein incident light striking the protective layer over a range of incidence angles has a first average path length through the PV material;

fabricating a PV enhancement film including extruding a web of plastic through a set of rollers including a chilled embossing roller to form a plurality of absorption enhancement structures on a first side of the plastic web;

applying a layer of adhesive to the second side of the plastic web; and

attaching the plastic web to the protective layer opposite the PV material via the adhesive layer,

wherein each of the absorption enhancement structures comprises a body shaped to transmit light incident upon an outer surface of the body toward the PV material at a differing angle than the incident light striking the protective layer and to direct at least a portion of light reflected from the PV material back toward the PV material using total internal reflection (TIR), wherein the light incident upon the body over the range of incidence angles has a second average path length that is at least about 10 percent greater than the first average path length.

18. The method of claim 17, wherein the protective layer comprises glass and the PV material comprises a silicon-based thin film PV device.

19. The method of claim 17, wherein the bodies of the absorption enhancement structures are elongated with triangular cross sectional shapes with two sides defining a light receiving and trapping surface using TIR to direct the portion reflected light back to the light-receiving surface and using refraction to provide the differing angle and wherein an average path length ratio of the second average path length to the first average path length is greater than about 1.2.

20. The method of claim 17, wherein the bodies of the absorption enhancement structures each are pyramid shaped with at least three facets, hemispherical shaped, or frustoconical shaped.

21. The method of claim 17, wherein the bodies each have a base width and a height of less than about 10 mils.

22. The method of claim 17, wherein the absorption enhancement structures comprise a plurality of elongated, side-by-side members, wherein the bodies of adjacent ones of the members differ in at least one of size or shape, and wherein an average path length ratio of the second average path length to the first average path length is greater than about 1.5.

23. The method of claim 17, wherein the absorption enhancement structures further comprise at least three differing body configurations in which the bodies of the members differ in at least one of size or shape.

24. A method of forming a photovoltaic (PV) enhancement film for use within a solar device with a light-receiving surface, comprising:

providing a volume of substantially transparent material at an extrusion temperature above ambient temperature; and

using a chilled embossing roller with a surface engraved with a pattern to form a plurality of absorption enhancement structures on a light receiving surface of a sheet of the substantially transparent material, wherein each of the absorption enhancement structures comprises at least one facet for receiving incident light on the light receiving surface, for directing the incident light toward the light-receiving surface of the solar device when placed proximate to the solar device whereby a path length in PV material of the solar device is greater than a base path length determined in an absence of the PV enhancement film, and for reflecting a portion of light reflected from the light-receiving surface of the solar device.

25. The method of claim 24, wherein the absorption enhancement structures comprise elongate members with at least two facets for the receiving and the directing of the incident light and for the reflecting of the portion of the reflected light, the reflecting being performed using total internal reflection (TIR) and wherein a ratio of the path length over the base path length is greater than about 1.2 on average over a range of incidence angles including the range of −

20 to +20 degrees as measured from an orthogonal plane extending from the light-receiving surface of the solar device.

26. The method of claim 24, wherein the absorption enhancement structures comprise a plurality of elongated and parallel members each having a triangular cross sectional shape, the sides of each of the members being angled inward at an angle of less than about 60 degrees, the members each having a base with a width of less than about 15 mils and a height of less than about 11 mils, wherein a first set of the members has a height of less than about 8 mils and a second set of the members has a height of greater than about 8 mils with the members of the first and second sets being mixed in a sawtooth pattern on the substrate.

27. The method of claim 24, wherein a ratio of the path length over the base path length is greater than about 1.5 on average over a range of incidence angles including the range of −

40 to +40 degrees as measured from an orthogonal plane extending from the light receiving surface.

28. The method of claim 25, wherein a ratio of the path length over the base path length is greater than about 1.5 on average over a range of incidence angles including the range of −

40 to +40 degrees as measured from an orthogonal plane extending from the light receiving surface.

30. A method of manufacturing a photovoltaic (PV) enhancement film, comprising:

providing an extrusion device comprising an embossing roller with a surface engraved with a contoured pattern corresponding to a plurality of absorption enhancement structures;

feeding a web of substantially transparent material at an extrusion temperature to the extrusion device; and

rolling the embossing roller against a first side of the web to form the plurality of absorption enhancement structures, wherein the absorption enhancement structures each comprise a light receiving surface that directs at least a portion of light that passes through a second side of the web toward the first side back toward the second side,

wherein the light receiving surface refracts incident light striking the first side to provide an average path length ratio of greater than about 1.10 when the embossed web is applied over a layer of PV material over a range of incidence angles.

31. The method of claim 30, wherein the average path length ratio is determined as an average of a plurality of path length ratios determined within the range of incidence angles and each of the path length ratios being a path length of the refracted incident light traveling through the PV material after passing through the PV enhancement film compared with a path length of the incident light traveling through the PV material in an absence of the PV enhancement film.

32. The method of claim 31, wherein the plurality of path length ratios is determined based on ray tracings performed at a plurality of angles within the range of incidence angles.

33. The method of claim 32, wherein the range of incidence angles is a range of angles selected from the range of negative 20 degrees to positive 20 degrees as measured from an orthogonal plane passing through a light-receiving surface of the PV material.

34. The method of claim 30, wherein adjacent ones of the absorption enhancement structures have differing heights as measured from the second side to a peak of the triangular cross section of the absorption enhancement structures.

35. The method of claim 30, wherein each of the absorption enhancement structures comprises an elongated body including a semi-circular cross section.

36. The method of claim 30, wherein each of the absorption enhancement structures has a body with a hemispherical shape with a base supported on the substrate.

37. The method of claim 30, wherein each of the absorption enhancement structures has a body with a pyramid or a frustoconical shape with a base supported on the substrate.