MULTI-JUNCTION SOLAR CELLS WITH A HOMOGENIZER SYSTEM AND COUPLED NON-IMAGING LIGHT CONCENTRATOR

• US 20090071467A1
• Filed: 09/08/2008
• Published: 03/19/2009
• Est. Priority Date: 07/28/2005
• Status: Active Grant

• Current Assignee: Light Prescriptions Innovators, LLC
• Original Assignee: Light Prescriptions Innovators, LLC
• Inventors: Dross, Oliver, Benitez, Pablo, Minano, Juan Carlos, Hernandez, Maikel, Blen, Jose, Mohedano, Ruben
• Granted Patent: US 8,631,787 B2
• Time in Patent Office: Days
• US Class Current: 126/685
• CPC Class Codes: F24S 23/31 having discontinuous faces, e.g. Fresnel lenses
• CPC Class Codes: F24S 23/71 with parabolic reflective surfaces with cylindro-parabolic reflective surfaces F24S23/74
• CPC Class Codes: F24S 23/79 with spaced and opposed interacting reflective surfaces
• 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

Abstract

The present embodiments provide methods and systems to homogenize illumination on a target. Some embodiments provide rotational symmetric dual-reflector solar concentrators that include a concave primary reflector with an aim-direction directed toward the sun to receive optical radiation in a far-field angle within an angle of acceptance and redirect radiation upward and centrally generating flux concentration, a secondary reflector positioned coaxial with said primary reflector to receive said redirected radiation and redirect radiation downward and centrally generating flux concentration solar rays, and a central target zone receiving said concentrated solar rays, where cross sections of said primary and secondary reflectors both further comprise a multiplicity of segments that establish a correspondence between pairs of segments, each of said segments of said primary reflector such as to image said angle of acceptance onto said corresponding segment of said secondary reflector to image onto said target zone.

Claims

1. A rotational symmetric dual-reflector solar concentrator employing Kohler integration to homogenize the illumination on the target, comprising:

a concave primary reflector with an aim-direction directed toward the sun, thereby defining an upward direction, said primary reflector receiving optical radiation therefrom in a far-field angle bounded within an angle of solar-ray acceptance about said aim-direction, said primary reflector redirecting said radiation upward and centrally, said central redirection by said primary reflector generating flux concentration;

a secondary reflector positioned coaxial with said primary reflector to receive said redirected radiation;

said secondary reflector being smaller than said primary reflector and accepting said redirected solar radiation therefrom;

said secondary reflector redirecting said solar radiation downward and centrally, said central redirection by said secondary reflector generating solar radiation concentration;

a central target zone receiving said concentrated solar radiation;

said primary and secondary reflector shaped so that when the sun is within said angle of acceptance the solar radiation is directed to said target zone; and

cross sections of said primary reflector and said secondary reflector both further comprise a multiplicity of curved segments subdividing said cross sections, said subdivision establishing a correspondence between pairs of segments of said primary and secondary reflectors, each of said segments of said primary reflector such as to image said angle of acceptance onto said corresponding segment of said secondary reflector, said corresponding segment of said secondary reflector such as to image said corresponding segment of said primary reflector onto said target zone.

2. The solar concentrator of claim 1 wherein said target zone is disposed in the vicinity of a vertex of said primary reflector.

3. The solar concentrator of claim 1 wherein said angle of acceptance is less than four degrees from said aim-direction.

4. The solar concentrator of claim 1 further comprising a central aperture formed in said primary reflector, said aperture allowing passage therethrough of said concentrated solar radiation onto said target zone, said target zone positioned below a vertex of said primary mirror.

5. The solar concentrator of claim 1 wherein said primary and secondary reflectors are separated by a distance comprising air within the distance and between the primary and secondary reflectors.

6. The solar concentrator of claim 5 further comprising a dielectric lens positioned aligned with said target zone.

7. The solar concentrator of claim 5 further comprising a central aperture formed in said primary reflector, said aperture allowing passage therethrough of said concentrated solar radiation onto said target zone, and a transparent cover disposed over the central aperture of said primary reflector.

8. The solar concentrator of claim 7 wherein said transparent cover supports said secondary reflector.

9. The solar concentrator of claim 1 further comprising at least one optically transparent dielectric media between said primary reflector and said secondary reflector and between said secondary reflector and said target zone.

10. The solar concentrator of claim 1 further comprising at least one photovoltaic cell disposed within said central target zone so as to receive at least a portion of the concentrated solar radiation and convert at least the portion of said concentrated solar radiation into electricity.

11. A rotational symmetric dual-reflector solar concentrator employing Kohler integration to homogenize the illumination on the target, comprising:

a refractive first surface of a transparent dielectric material, said first surface oriented to receive solar radiation in air;

a refractive second surface receiving said radiation from said first surface,

a concave primary reflector having an aim-direction directed toward the sun, thereby defining an upward direction, said first and second surfaces positioned upward of said primary reflector, said primary reflector receiving radiation therefrom in a far-field angle of acceptance of solar rays, said angle bounded within an angle of solar-ray acceptance about said aim-direction, said primary reflector redirecting said radiation upward and centrally, said central redirection by said primary reflector generating solar concentration;

a secondary reflector positioned above said primary reflector and coaxial therewith;

said secondary reflector being smaller than said primary reflector and accepting said redirected solar radiation therefrom;

said secondary reflector redirecting said solar radiation downward and centrally, said central redirection by said secondary reflector generating solar concentration;

a refractive exit surface receiving said concentrated solar rays and passing them therethrough;

a central target zone receiving said concentrated solar rays from said exit surface; and

where said first and second refractive surfaces and said primary reflector and said secondary reflector and said exit surface being five successive surfaces, said five surfaces shaped to act so when the sun is within said angle of acceptance the solar radiation is directed to said target zone,

where three of said five surfaces are fixed and the remaining two are designable and designated as first and second designable surfaces;

where each of said designable surfaces comprises segmentation that subdivides a cross section of said first and second designable surfaces into corresponding pairs of segments, said subdivision establishing a correspondence between pairs of segments of the cross sections of said first and second designable surfaces, each of said segments of said first designable surface such as to image said angle of acceptance onto said corresponding segment of said second designable surface, said corresponding segment of said second designable surface such as to image said corresponding segment of said first designable surface onto said target zone.

12. The solar concentrator of claim 11 wherein said target zone is disposed proximate to a vertex of said primary reflector.

13. The solar concentrator of claim 11 wherein said angle of acceptance comprises all rays less than four degrees from said aim-direction.

14. The solar concentrator of claim 11 further comprising a central aperture defined within said primary reflector, said aperture allowing passage therethrough of said concentrated rays onto said target zone, said target zone positioned below a vertex of said primary mirror.

15. The solar concentrator of claim 11 further comprising at least one photovoltaic cell disposed within said central target zone so as to receive at least a portion of the concentrated solar radiation and convert at least the portion of said concentrated solar rays into electricity.

16. The solar concentrator of claim 11 wherein said first designable surface is said refractive first surface and said second designable surface is said refractive second surface.

17. The solar concentrator of claim 11 wherein said first designable surface is said refractive first surface and said second designable surface is said primary reflector.

18. The solar concentrator of claim 11 wherein said first designable surface is said refractive first surface and said second designable surface is said secondary reflector.

19. The solar concentrator of claim 11 wherein said first designable surface is said refractive first surface and said second designable surface is said refractive exit surface.

20. The solar concentrator of claim 11 wherein said first designable surface is said refractive second surface and said second designable surface is said primary reflector.

21. The solar concentrator of claim 11 wherein said first designable surface is said refractive second surface and said second designable surface is said secondary reflector.

22. The solar concentrator of claim 11 wherein said first designable surface is said refractive second surface and said second designable surface is said refractive exit surface.

23. The solar concentrator of claim 11 wherein said first designable surface is said primary reflector and said second designable surface is said refractive exit surface.

24. The solar concentrator of claim 11 wherein said first designable surface is said secondary reflector and said second designable surface is said refractive exit surface.

25. The solar concentrator of claim 11 wherein said first designable surface is said primary reflector and said second designable surface is said secondary reflector.

26. The solar concentrator of claim 25 wherein said refractive exit surface has a central convexity.

27. The solar concentrator of claim 25 wherein said refractive exit surface has a central concavity.

28. An optical device, comprising:

an aplanatic optical imaging system including;

a) a segmented primary reflective element defining an entrance aperture and having a plurality of aspherical primary reflective segments; and

b) a segmented secondary reflective element having a plurality of aspherical secondary reflective segments, wherein primary and secondary reflective segments are pair-wise correlated so that a primary reflective segment images a field of view onto a corresponding secondary reflective segment, and wherein the secondary reflective segment images the corresponding primary segment onto an exit aperture; and

a target element positioned proximal to a vertex of the primary reflective element.

29. The device of claim 28, wherein the exit aperture is substantially contiguous with the vertex of the primary mirror element.

30. The device of claim 28, wherein the target element comprises a solar cell.

31. The device of claim 28, further comprising a cover positioned proximal to the entrance aperture.

32. The device of claim 28, wherein the plurality of primary and secondary reflective segments are radially symmetric with respect to a central axis.

33. The device of claim 28, wherein the space between the primary and secondary reflective elements comprises air.

34. The device of claim 28, wherein the space between the primary and secondary reflective elements comprises a dielectric material with an index of refraction, n.

35. The device of claim 28, further comprising a flow line concentrator disposed proximal to the exit aperture.

36. An optical device, comprising:

an aplanatic optical imaging system including;

a) a segmented primary reflective element defining an entrance aperture and having a plurality of primary reflective segments; and

b) a segmented secondary reflective element having a plurality of secondary reflective segments, and

a target element positioned proximal to an exit aperture,

wherein primary and secondary reflective segments are pair-wise correlated so that light impinging on a primary reflective segment is focused onto a corresponding secondary reflective segment, and wherein the secondary reflective segment images the corresponding primary segment onto the exit aperture such that the target element is substantially uniformly illuminated.

37. The device of claim 36, wherein the primary reflective segments and the secondary reflective segments are aspherical.

38. The device of claim 36, wherein the target element includes a solar cell.

41. The method of claim 36, wherein the primary reflective segments and the secondary reflective segments are aspherical.

39. A method of concentrating light onto a solar cell, the method comprising:

positioning an aplanatic optical imaging device to receive incident light from a light source, the device including a segmented primary reflective element having a plurality of primary reflective segments, and a segmented secondary reflective element having a plurality of corresponding secondary reflective segments,

reflecting incident light by the primary mirror segment s onto corresponding secondary mirror segments; and

reflecting the reflected light by the secondary mirror segments onto a target cell, wherein the target cell is substantially uniformly illuminated by the incident light.

40. The method of claim 39, wherein the light source is the sun, and wherein the method further includes repositioning the device so as to track the motion of the sun such that incident light from the sun is received within an acceptance angle of the device.