Inflated tubular solar concentrators

Abstract

A solar collector utilizes an inflated tubular film which concentrates sunlight onto a solar receiver. The film incorporates refractive elements in a pattern which focuses light in one or two dimensions to create foci in the form of lines, spots, or other shapes. The film may be replaceable. The film may include layers of material to optimize optical, structural, thermal, and durability characteristics.

What is claimed is: 
     
         1 . A solar concentrator comprising:
 a film configured to refract sunlight, wherein the film forms a tubular shape enclosing a cavity, wherein a first portion of the film includes a refractive region configured to direct the incident sunlight towards one or more focus regions within the cavity;   an inflation gas at least partially filling the cavity, wherein the inflation gas is configured to maintain the tubular shape of the film; and   a receiver configured to capture the energy in the sunlight refracted from the film, the receiver being located inside the cavity and at one of the one or more focus regions.   
     
     
         2 . The solar concentrator of  claim 1  wherein each focus region comprises one or more focal points. 
     
     
         3 . The solar concentrator of  claim 1  wherein the solar concentrator further comprises circuitry to convert the captured energy in the sunlight to electrical energy. 
     
     
         4 . The solar concentrator of  claim 1  wherein the solar concentrator further comprises a thermal energy receiver. 
     
     
         5 . The solar concentrator of  claim 1  wherein the refractive region comprises a plurality of prisms configured to refract the sunlight. 
     
     
         6 . The solar concentrator of  claim 5  wherein the plurality of prisms are arranged in two or more groups of prisms. 
     
     
         7 . The solar concentrator of  claim 6  wherein the two or more groups of prisms are arranged symmetrically within the refractive region. 
     
     
         8 . The solar concentrator of  claim 5  wherein each prism comprises one or more grooves, each groove having a depth. 
     
     
         9 . The solar concentrator of  claim 1  wherein the refractive region is about 30% to 50% of a total surface area of the tubular shape. 
     
     
         10 . The solar concentrator of  claim 1  wherein the refractive region comprises a plurality of tiles, each tile having an area and including one or more prism grooves. 
     
     
         11 . The solar concentrator of  claim 10  wherein the plurality of tiles includes a first tile having a first area and a second tile having a second area, and wherein the first area is larger than the second area. 
     
     
         12 . The solar concentrator of  claim 11  wherein the first tile is located at a first distance from a center of the refractive region and the second tile is located at a second distance from the center of the refractive region, and wherein the first distance is less than the second distance. 
     
     
         13 . The solar concentrator of  claim 1  wherein the film is comprises one or more of PET, acrylic, Polyolefins, Ionomer, or Fluorinated polymers. 
     
     
         14 . The solar concentrator of  claim 1  wherein a portion of the film comprises a metal. 
     
     
         15 . The solar concentrator of  claim 1  wherein the tubular shape has an axis and a diameter and wherein the receiver comprises an active element having a width, wherein the active element is disposed perpendicular to the axis and the width of the active element is less than 15% of the diameter of the tubular shape. 
     
     
         16 . A solar concentrator system comprising:
 one or more tubular solar concentrators configured to receive sunlight and direct the sunlight to a receiver located within each of the one or more tubular solar concentrators; and   a support structure configured to hold the one or more tubular solar concentrators, wherein the support structure further comprises:
 a base frame configured to rotate about an azimuth rotation axis; 
 an upper frame configured to rotate about an elevation rotation axis; and 
 a tracking mechanism configured to continually track the position of the Sun and to position the base frame and the upper frame to follow a path of the Sun. 
   
     
     
         17 . The solar concentrator system of  claim 16  wherein the upper frame comprises one or more rollers, sliders, or linkage arms configured to move the support structure about the elevation rotation axis. 
     
     
         18 . The solar concentrator system of  claim 17  wherein the one or more rollers, sliders, or linkage arms are disposed substantially farther from the elevation rotation axis. 
     
     
         19 . A solar concentrator comprising:
 a transparent film configured to refract incident sunlight;   wherein the transparent film is part of a cylinder structure and the transparent film refracts the incident sunlight to concentrate it in more than one direction.   
     
     
         20 . The solar concentrator of  claim 19  wherein the cylinder structure has a longitudinal cylinder axis and at least one direction in which the incident sunlight is concentrated is not perpendicular to the longitudinal cylinder axis. 
     
     
         21 . The solar concentrator of  claim 19  wherein a direction of refracted sunlight varies at each point on a surface of the cylinder structure that refracts the incident sunlight. 
     
     
         22 . The solar concentrator of  claim 19  further comprising one or more focal regions disposed within the cylinder structure, wherein an average illumination level at the one or more focal regions is about 500 to 2000 times more than an illumination level of the incident sunlight. 
     
     
         23 . The solar concentrator of  claim 19  wherein a substantial amount of the refracted sunlight is focused at one or more points within the cylinder. 
     
     
         24 . The solar concentrator of  claim 19  wherein the transparent film comprises Polyethylene terephthalate (PET). 
     
     
         25 . The solar concentrator of  claim 19  wherein the transparent film has a front surface and an opposing back surface, and wherein a plurality of grooves are disposed on the front surface, or the back surface, or both the front and back surfaces. 
     
     
         26 . The solar concentrator of  claim 25  further comprising one or more tiles disposed on the front surface, or the back surface, or both the front and back surfaces, each of the one or more tiles including a set of grooves from the plurality of grooves. 
     
     
         27 . A solar concentrator comprising:
 a film structure configured to receive and refract incident light, wherein the film structure comprises two or more layers, wherein a first layer in the film structure comprises Polyethylene terephthalate (PET), and   wherein the film structure is configured in a shape of a cylinder enclosing an inflation space, the inflation space being occupied by a gas.   
     
     
         28 . The solar concentrator of  claim 27  wherein the film structure comprises a second layer disposed below the first layer, wherein the second layer comprises acrylic, fluorinated acrylic, ionomer, or other fluorinated polymer. 
     
     
         29 . The solar concentrator of  claim 28  wherein a thickness of the second layer ranges between 0.001 mm and 0.1 mm. 
     
     
         30 . The solar concentrator of  claim 28  further comprising a plurality of grooves formed in the second layer. 
     
     
         31 . The solar concentrator of  claim 27  wherein the film structure comprises a second layer disposed on top of the first layer and wherein the second layer comprises fluorinated polymer or silicone. 
     
     
         32 . The solar concentrator of  claim 31  wherein the second layer further comprises an ultraviolet (UV) radiation absorbing material. 
     
     
         33 . The solar concentrator of  claim 32  wherein the UV absorbing material comprises fluorinated acrylic. 
     
     
         34 . The solar concentrator of  claim 31  wherein the film structure further comprises a third layer disposed between the second layer and the first layer, the third layer configured to block ultraviolet radiation from reaching the first layer. 
     
     
         35 . The solar concentrator of  claim 31  wherein the film structure further comprises a third layer disposed between the second layer and the first layer, the third layer configured to prevent the migration of chemical compounds between the first layer and the second layer. 
     
     
         36 . The solar concentrator of  claim 27  wherein the film structure comprises a second layer disposed on top of the first layer and wherein the second layer comprises a material resistant to (a) temperatures in the range of −40° C. to 80° C., (b) humidity in the range of 0-100% relative humidity, and (c) ultraviolet (UV) exposure. 
     
     
         37 . The solar concentrator of  claim 27  wherein the PET comprises an ultraviolet light absorber material as an additive. 
     
     
         38 . A solar concentrator comprising:
 a first film configured to be exposed to incident sunlight;   a second film attached to the first film and configured to provide structural support, wherein the first film and the second film together form a tubular structure having an enclosed inflation space; and   a receiver detachably connected to the second film and configured to receive refracted sunlight from the first film.   
     
     
         39 . The solar concentrator of  claim 38  wherein the first film refracts incident sunlight to create one or more areas of concentrated solar energy. 
     
     
         40 . The solar concentrator of  claim 38  wherein the second film comprises a metal. 
     
     
         41 . A solar concentrator system comprising:
 a film having a tubular shape and attached to an elongated chassis;   one or more heat sink elements connected to a first surface of the elongated chassis along the length of the elongated chassis, wherein each of the one or more heat sink elements comprises one or more fin structures, and wherein the one or more heat sink elements are connected to the first surface using a material having a thermal conductivity between 0.005 W/m-k and 180 W/m-k;   one or more photovoltaic cells coupled to a second surface of the one or more heat sink elements; and   one or more optical elements configured to direct incident sunlight onto the one or more photovoltaic cells,   wherein the one or more heat sink elements is configured to dissipate heat generated at the one or more photovoltaic cells.   
     
     
         42 . The solar concentrator system of  claim 41  wherein the film comprises one or more refractive prism elements configured to concentrate incident sunlight. 
     
     
         43 . The solar concentrator system of  claim 42  wherein the film encloses an inflation space and wherein the one or more photovoltaic cells are located within the inflation space. 
     
     
         44 . The solar concentrator system of  claim 43  wherein the inflation space comprises a gas including one of: air, helium, carbon dioxide, nitrogen, argon, hydrogen, oxygen, or water vapor. 
     
     
         45 . The solar concentrator system of  claim 42  wherein the film encloses an inflation space and wherein the one or more photovoltaic cells are located at a surface of the tubular structure. 
     
     
         46 . The solar concentrator system of  claim 42  wherein the tubular structure encloses an inflation space and wherein the one or more photovoltaic cells are located outside a perimeter defined by the tubular shape. 
     
     
         47 . A solar concentrator system comprising:
 one or more tubular solar concentrators configured to capture and concentrate sunlight, wherein each tubular solar concentrator has a longitudinal axis and first rotation axis parallel to the longitudinal axis and wherein the tubular concentrator is configured to rotate about the first rotation axis; and   one or more receivers, each receiver coupled to at least one of the one or more tubular solar concentrators, the receiver configured to capture energy from the concentrated sunlight and translate in a direction perpendicular to the first rotation axis.