Passively Cooled Solar Concentrating Photovoltaic Device

• US 20070256724A1
• Filed: 05/05/2006
• Published: 11/08/2007
• Est. Priority Date: 05/05/2006
• Status: Active Grant

• Current Assignee: Solfocus, Inc., Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Horne, Stephen, Fork, David
• Granted Patent: US 7,851,693 B2
• Time in Patent Office: Days
• US Class Current: 136/246
• CPC Class Codes: H01L 31/052 Cooling means directly associated or integrated with the PV cell, e.g. integrated Peltier elements for active cooling or heat sinks directly associated with the PV cells cooling means in combination with the PV module H02S40/42
• 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 10/52 PV systems with concentrators

Abstract

A Cassegrain-type concentrating solar collector cell includes primary and secondary mirrors disposed on opposing convex and concave surfaces of a light-transparent (e.g., glass) optical element. Light enters an aperture surface surrounding the secondary mirror, and is reflected by the primary mirror toward the secondary mirror, which re-reflects the light onto a photovoltaic cell. The photovoltaic cell is mounted on a central portion of heat spreader that extends over the primary mirror. The heat spreader transmits waste heat from the photovoltaic cell in a manner that evenly distributes the heat over the optical element, thereby maximizing the radiation of heat from the aperture surface into space. The heat spreader includes a thick copper layer formed on a flexible substrate (e.g., polyimide film) that is patterned with radial arms that facilitate mounting onto the convex surface of the optical element.

Claims

1. A concentrating photovoltaic (CPV) device comprising:

a solid, light-transparent optical element having opposing first and second surfaces and defining a focal point at which light received by the optical element is concentrated;

a heat spreader including a central portion disposed over the of the optical element, and one or more peripheral portions extending from the central portion over the first surface; and

a photovoltaic (PV) cell disposed on the central portion of the heat spreader.

2. The CPV device according to claim 1,

wherein the heat spreader has a lateral thermal resistance extending from the central portion to the peripheral portions,

wherein the optical element has a transverse thermal resistance extending from the first surface to the second surface, and

wherein the transverse thermal resistance is greater than the lateral thermal resistance.

3. The CPV device according to claim 1,

wherein the optical element comprises glass having a thickness in the range of 5 to 12 mm and a diameter of approximately 28 mm, and

wherein the heat spreader comprises copper having a nominal thickness of approximately 70 microns.

4. The concentrating solar collector according to claim 1, wherein the heat spreader comprises a laminate structure including one or more non-conductive layers and one or more metallization layers.

5. The CPV device according to claim 4,

wherein the one or more non-conductive layers comprise a polyimide film, and

wherein the one or more metallization layers comprise one of copper and Fe—

Ni alloy.

6. The CPV device according to claim 4, wherein the PV cell is electrically connected to one or more of the metallization layers.

7. The CPV device according to claim 1, wherein the one or more peripheral portions comprise a plurality of radial arms extending from the central portion, wherein each adjacent pair of radial arms is separated by an associated slit.

8. The CPV device according to claim 1,

wherein the optical element comprises a relatively large convex surface defining a central first side region, and an opposing aperture surface and a relatively small curved surface defined in a central portion of the aperture surface,

wherein the central first side region comprises a cavity, and

wherein the PV cell is disposed inside the cavity between the central portion of the heat spreader and an adjacent surface of the optical element.

9. The CPV device according to claim 8, further comprising a transparent adhesive disposed in the cavity between the PV cell and said adjacent surface of the optical element.

10. The CPV device according to claim 8, further comprising a primary mirror disposed between the convex surface and the peripheral portions of the heat spreader, and a secondary mirror disposed on the curved surface, wherein the primary and secondary mirrors are arranged such that light entering the optical element through the aperture surface is concentrated onto the central first side region, whereby the concentrated light generates heat in the central first side region.

11. The CPV device according to claim 10, wherein the primary mirror and secondary mirror comprise reflective mirror films formed directly onto the convex surface and the curved surface, respectively.

12. The CPV device according to claim 11, wherein the primary mirror and the secondary mirror comprise silver, and wherein the heat spreader comprises copper.

13. The CPV device according to claim 10, wherein each of the primary mirror and secondary mirror comprises a reflective mirror layer, an anti migration layer formed on the reflective mirror layer, and zero or more barrier paint layers formed on the anti-migration layer.

14. The CPV device according to claim 10, wherein the reflective mirror layer comprises silver, and wherein the anti-migration layer comprises copper.

15. The CPV device according to claim 1, further comprising a protective shell layer disposed on a backside surface of the heat spreader.

16. A concentrating photovoltaic (CPV) device comprising:

a solid, light-transparent optical element having a relatively large convex surface defining a central first side region, and an opposing aperture surface and a relatively small curved surface defined in a central portion of the aperture surface;

a heat spreader including a central portion disposed over the central first side region of the optical element, and a plurality of radial arms extending from the central portion and conformally disposed over the convex surface; and

a photovoltaic (PV) cell disposed on the central portion of the heat spreader and being electrically connected to at least one of the plurality of radial arms.

17. The CPV device according to claim 16, wherein the heat spreader comprises a laminate structure including one or more non-conductive layers and one or more metallization layers.

18. The CPV device according to claim 16,

wherein the one or more non-conductive layers comprise a polyimide film, and

wherein the one or more metallization layers comprise one of copper and Fe—

Ni alloy.

19. The CPV device according to claim 16,

wherein the heat spreader has a lateral thermal resistance extending from the central portion to the peripheral portions,

wherein the optical element has a transverse thermal resistance extending from the convex surface to the aperture surface, and

wherein the transverse thermal resistance is greater than the lateral thermal resistance.

20. A method for producing a concentrating photovoltaic (CPV) device comprising:

forming a solid, light-transparent optical element having a relatively large convex surface defining a central first side region, and an opposing aperture surface and a relatively small curved surface defined in a central portion of the aperture surface;

forming a heat spreader including a central portion disposed over the central first side region of the optical element, and a extending from the central portion; and

mounting the heat spreader onto the optical element ouch that the peripheral portion is conformally disposed over the convex surface.

21. The method of claim 20, further comprising:

mounting a photovoltaic (PV) cell on the central portion of the heat spreader,

wherein mounting the heat spreader on the optical element comprises disposing the PV cell inside the central first side region.

22. The method of claim 20, further comprising separating the peripheral portion into a plurality of radial fingers prior to mounting the heat spreader onto the optical element.