Asymmetric solar collector system

Abstract

An symmetric solar collector system is disclosed which comprises one or more reflectors in the shape of an asymmetrical vertically-biased parabolic trough, which allows for the reflectors to be stacked vertically, and have a zero footprint. The reflectors each include a reinforced absorber comprising two or more tubes attached to each other in truss-like fashion, with a sag to length ratio of less than about 1/500. In addition, although the vertically-biased trough shape lessens the amount of surface area available for water or ice to accumulate, the reflector surface is partially coated with a material that is highly absorptive of solar wavelengths, and thus, heats any accumulated water/ice to the point of evaporation.

1 . A solar collector comprising:
 a) a reflector assembly for receiving solar radiation; and   b) an absorber positioned for receiving solar radiation reflected from said reflector assembly, wherein   
       said reflector assembly comprises a reflector surface having a longitudinal cross-sectional shape of an asymmetric parabola with a vertical bias. 
     
     
         2 . The solar collector of  claim 1 , wherein said reflector assembly has a forward vertical bias angle of between 5 and 45 degrees. 
     
     
         3 . The solar collector of  claim 2 , wherein said reflector assembly has a forward vertical bias angle of between 15 and 30 degrees. 
     
     
         4 . The solar collector of  claim 2 , wherein said reflector assembly has a forward vertical bias angle of between 18 and 22 degrees 
     
     
         5 . The solar collector of  claim 1 , wherein said reflector assembly comprises a reflector surface consisting of polished anodized aluminium protected by an anti-oxidizing micro-coating; an aluminium foil over a substrate; a mirrored flexible sheet material; a mirrored surface; or a back side reflectively-coated material. 
     
     
         6 . The solar collector of  claim 5 , wherein said mirrored flexible sheet material is mirrored polycarbonate, mirrored acrylic or mirrored fibreglass. 
     
     
         7 . The solar collector of  claim 1  further comprising a means of rotation about an axis adjacent to said absorber. 
     
     
         8 . A device for solar energy collection comprising a plurality of solar collectors of  claim 1  mounted on a plurality of rows adjacent to a vertical or near-vertical surface. 
     
     
         9 . The solar collector of  claim 1 , wherein said absorber comprises two or more tubes aligned adjacently along an entire length of each said tube; and a means for joining said tubes along their lengths, said joining means being thermally stable and rigid. 
     
     
         10 . The solar collector of  claim 9 , wherein said joining means is discontinuous along said length of said tubes. 
     
     
         11 . The solar collector of  claim 9 , wherein said absorber has a sag to length ratio of about 1/500 or less. 
     
     
         12 . The solar collector of  claim 9 , wherein said tubes are preflexed in a direction joining the centres of said tubes. 
     
     
         13 . The solar collector of  claim 9 , wherein each said tube is partially flattened along part of its length. 
     
     
         14 . The solar collector of  claim 13 , wherein two tubes are used, and are joined longitudinally at an angle. 
     
     
         15 . The solar collector of  claim 9 , wherein said absorber has a coating having high absorbance for sunlight wavelengths and low emissivity for blackbody wavelengths at ambient temperature. 
     
     
         16 . The solar collector of  claim 9 , wherein said absorber further comprises glazing, insulation, or a back plate. 
     
     
         17 . The solar collector of  claim 1 , wherein said reflective assembly comprises a reflective surface partially covered with material that is highly absorptive of solar wavelengths. 
     
     
         18 . The solar collector of  claim 17 , wherein said material has a total area that is less than or equal to about 5% of the total surface area of said reflective surface. 
     
     
         19 . The solar collector of  claim 17 , wherein said material is used for removal of liquid water or ice from said reflective surface. 
     
     
         20 . The solar collector in  claim 1 , wherein said reflective assembly comprises a frame partially covered with material that is highly absorptive of solar wavelengths. 
     
     
         21 . The solar collector in  claim 20 , wherein said frame is in thermal contact with said reflective surface. 
     
     
         22 . The solar collector of  claim 20 , wherein said material is used for removal of liquid water or ice from said reflective surface. 
     
     
         23 . A solar absorber having a truss-like structure, comprising two or more tubes and a means of joining said tubes, wherein said absorber has a sag to length ratio of about 1/500 or less.