Rotational Trough Reflector Array For Solar-Electricity Generation

Abstract

A rotational trough reflector solar-electricity generation device includes a trough reflector that rotates around a substantially vertical axis. A strip-type photovoltaic (PV) device, or other solar-energy collection element, is fixedly mounted along the focal line of the trough reflector. A tracking system rotates the trough reflector such that the trough reflector is aligned generally parallel to the incident sunlight (e.g., in a generally east-west direction at sunrise, turning to generally north-south at noon, and turning generally west-east at sunset). A disc-shaped support structure is used to distribute the reflector's weight over a larger area and to minimize the tracking system motor size. Multiple trough reflectors are mounted on the disc-shaped support to maximize power generation. Flat mirrors are disposed at the end of the troughs to increase power in “hot” PV sections that are connected in series.

1 . An apparatus for solar-energy collection comprising:
 a first trough reflector having a reflective surface defining a first focal line;   a first solar-energy collection element disposed on the first focal line; and   means for rotating the first trough reflector around an axis, wherein the axis is non-parallel to the focal line.   
     
     
         2 . The apparatus of  claim 1 , further comprising a support structure connected to the first trough reflector and to the first solar-energy collection element such that the first solar-energy collection element is maintained in a fixed position relative to the first trough reflector. 
     
     
         3 . The apparatus of  claim 2 , wherein the support structure comprises one of a transparent support member and a plurality of support arms extending between the first trough reflector and the first solar-energy collection element. 
     
     
         4 . The apparatus of  claim 1 , wherein said axis is disposed substantially perpendicular to the first focal line such that the solar-energy collection element remains in a predetermined plane that is perpendicular to the axis when said first trough reflector rotates around said axis. 
     
     
         5 . The apparatus of  claim 1 , wherein said means comprises a tracking system including means for detecting a position of the sun relative to trough reflector, and means for rotating the trough reflector such that the first focal line is parallel to solar beams generated by the sun that are directed onto the trough reflector. 
     
     
         6 . The apparatus of  claim 1 , wherein said tracking system including means for controlling a rotational position of the trough reflector such that:
 during a sunrise time period, the focal line is aligned in a first generally east-west direction,   during a midday time period, the focal line is aligned in a generally north-south direction, and   during a sunset time period, the focal line is aligned in a second generally east-west direction.   
     
     
         7 . The apparatus of  claim 1 ,
 wherein the first trough reflector has a longitudinal length measured parallel to the focal line,   wherein said means comprises a circular base structure including means for rotating relative to an underlying support surface around said axis, and having a peripheral edge defining a diameter that is greater than or equal to the longitudinal length of said first trough reflector, and   wherein the first trough reflector is fixedly mounted on the circular base structure such that rotation of the circular base structure relative to said underlying support surface produces rotation of the first trough reflector around said axis.   
     
     
         8 . The apparatus of  claim 7 , wherein said means comprises a tracking system including:
 a drive system coupled to the peripheral edge of the circular base structure,   means for detecting a position of the sun relative to trough reflector, and   means for causing the drive system to apply torque to the peripheral edge of the circular base structure such that the trough reflector is rotated into a position in which the first focal line is parallel to solar beams generated by the sun that are directed onto the trough reflector.   
     
     
         9 . The apparatus of  claim 7 , further comprising one or more second trough reflectors fixedly coupled to said circular base structure, each of said one or more second trough reflectors including an associated focal line, wherein the associated focal lines of the one or more second trough reflectors are parallel to the focal line of the first trough reflector. 
     
     
         10 . The apparatus of  claim 1 , further comprising one or more second trough reflectors fixedly coupled to said first trough reflector, each of said one or more second trough reflectors including an associated focal line, wherein the associated focal lines of the one or more second trough reflectors are parallel to the first focal line of the first trough reflector. 
     
     
         11 . The apparatus of  claim 10 , wherein said one or more second trough reflectors and said first trough reflector are disposed in a raised and tilted position such that a plane defined by said one or more second trough reflectors and said first trough reflector defines an angle with reference to said axis. 
     
     
         12 . The apparatus of  claim 11 , further comprising a tilt mechanism for selectively controlling said raised and tilted position. 
     
     
         13 . The apparatus of  claim 10 ,
 wherein each of said one or more second trough reflectors and said first trough reflector further comprises an associated flat mirror disposed adjacent to an end thereof,   wherein each of said one or more second trough reflectors and said first trough reflector includes a first photovoltaic section disposed on its focal line adjacent to said associated flat mirror, and a second photovoltaic section disposed on its focal line away from said associated flat mirror, and   wherein the first photovoltaic sections of each of said one or more second trough reflectors and said first trough reflector are connected in series.   
     
     
         14 . The apparatus of  claim 10 ,
 wherein the solar-energy collection element comprises a thermally efficient receiver tube disposed on the focal lines of said one or more second trough reflectors and said first trough reflector, and   wherein the apparatus further comprises means for circulating a thermal transfer fluid through the thermally efficient receiver tube.   
     
     
         15 . The apparatus of  claim 10 , wherein the solar-energy collection element comprises one of a photovoltaic material, a thermally efficient receiver tube, and a thermoelectric material. 
     
     
         16 . A method for generating solar-electricity using a first trough reflector, wherein the first trough reflector defines a first focal line, the method comprising:
 disposing the first trough reflector on a planar support surface such that the first focal line defines an angle relative to the planar support surface; and   rotating the first trough reflector around an axis that is substantially perpendicular to the planar support surface, whereby the first focal line remains disposed at said angle relative to said planar surface while said first trough reflector rotates around said axis.   
     
     
         17 . The method of  claim 16 , further comprising fixedly mounting a first photovoltaic element to the first trough reflector such that the first photovoltaic element is disposed along the first focal line, whereby rotation of the first trough reflector causes said first photovoltaic element to rotate around the axis while remaining within the plane. 
     
     
         18 . The method of  claim 16 , further comprising:
 detecting a position of the sun relative to trough reflector, and   rotating the trough reflector such that the first focal line is parallel to solar beams generated by the sun that are directed onto the trough reflector.   
     
     
         19 . The method of  claim 18 , wherein said rotating the trough reflector comprises:
 during a sunrise time period, aligning the focal line in a first generally east-west direction,   during a midday time period, aligning the focal line in a generally north-south direction, and   during a sunset time period, aligning the focal line in a second generally east-west direction.   
     
     
         20 . The method of  claim 16 , wherein disposing the first trough reflector on the planar support surface comprises disposing the first trough reflector on a roof of a residential house. 
     
     
         21 . The method of  claim 16 , wherein disposing the first trough reflector on the planar support surface comprises disposing the first trough reflector on a circular base structure mounted on the planar support surface, wherein the circular base structure includes a peripheral edge defining a diameter that is greater than or equal to a longitudinal length of said first trough reflector, and
 wherein rotating the first trough reflector comprises applying a force to the peripheral edge of the circular base structure such that the circular base structure rotates relative to the planar support surface around said axis.   
     
     
         22 . The method of  claim 21 , further comprising fixedly connecting one or more second trough reflectors to said circular base structure, each of said one or more second trough reflectors including an associated focal line, wherein the associated focal lines of the one or more second trough reflectors are parallel to the focal line of the first trough reflector. 
     
     
         23 . The method of  claim 22 , further comprising fixedly connecting one or more second trough reflectors to said first trough reflector, each of said one or more second trough reflectors including an associated focal line, wherein the associated focal lines of the one or more second trough reflectors are parallel to the focal line of the first trough reflector such that rotating the first trough reflector around the axis causes said associated focal lines to remain disposed within the plane. 
     
     
         24 . A method for generating solar-electricity using a trough reflector, wherein the trough reflector defines a focal line, the method comprising:
 mounting the trough reflector onto a planar support surface such that the focal line defines a predetermined angle relative to the support surface, and   rotating the trough reflector around an axis that is substantially perpendicular to the support surface such that:
 during a sunrise time period, the focal line is aligned in a first generally east-west direction, 
 during a midday time period, the focal line is aligned in a generally north-south direction, and 
 during a sunset time period, the is aligned in a second generally east-west direction. 
   
     
     
         25 . The method of  claim 24 , wherein mounting the trough reflector comprises mounting the trough reflector on a rooftop surface of a residential house.