Passively Cooled Solar Concentrating Photovoltaic Device

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.

1 . 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 comprising a thermally conductive material and 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 such that the radial arms are conformally disposed over and in thermal contact with 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.   
     
     
         2 . The CPV device 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. 
     
     
         3 . The CPV device according to  claim 1 ,
 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.   
     
     
         4 . 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 convex surface to the aperture surface, and   wherein the transverse thermal resistance is greater than the lateral thermal resistance.   
     
     
         5 . 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   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,   wherein the heat spreader comprise a thermally conductive material and the plurality of radial arms are in thermal contact with and conformally disposed over the convex surface such that heat generated at the focal region is passively transmitted from the central portion to the plurality of radial arms, and from the plurality of radial arms through the optical element for radiation from the substantially flat aperture surface.   
     
     
         6 . The CPV device according to  claim 5 , wherein the heat spreader comprises a laminate structure including one or more non-conductive layers and one or more metallization layers. 
     
     
         7 . The CPV device according to  claim 5 ,
 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.   
     
     
         8 . The CPV device according to  claim 5 ,
 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.