Photovoltaic (pv) enhancement films or protective covers for enhancing solar cell efficiencies

Abstract

A solar energy conversion assembly for efficiently capturing solar energy by providing additional chances to absorb reflected sunlight and providing longer path lengths in the photovoltaic (PV) material. The assembly includes a PV device including a layer of PV material and a protective top covering the PV material (e.g., a planar glass cover applied with adhesive to the PV material). The assembly further includes a PV enhancement film formed of a substantially transparent material, and film is applied to at least a portion of the protective top such as with a substantially transparent adhesive. The PV enhancement film includes a plurality of absorption enhancement structures on the substrate opposite the PV device. Each absorption enhancement structure includes a light receiving surface that refracts incident light striking the PV enhancement film to provide an average path length ratio of greater than about 1.20 in the layer of PV material.

1 . (canceled) 
     
     
         2 . A film for changing a direction of light passing through the film, the film comprising:
 a substrate of substantially transparent material; and   a plurality of structures on a side of the substrate,   wherein the structures refract light that strike the structures,   wherein each of the structures comprises a body formed of substantially transparent material, and   wherein the bodies each have a base width and a height of less than 10 mils.   
     
     
         3 . The film for changing the direction of light passing through the film of  claim 2 , wherein the structures comprise first and second sets with at least two differing body configurations such that the base width or the height of the first set differs from the base width or the height of the second set. 
     
     
         4 . The film for changing the direction of light passing through the film of  claim 2 , wherein each of the bodies is an elongated shape with at least two sides angled inward. 
     
     
         5 . The film for changing the direction of light passing through the film of  claim 4 , wherein each of the bodies has a triangular cross section when taken along a plane passing orthogonal to a longitudinal axis, and wherein the sides are angled inward at angles of less than 60 degrees. 
     
     
         6 . The film for changing the direction of light passing through the film of  claim 5 , wherein adjacent bodies have differing heights as measured from the substrate to a peak of the triangular cross section. 
     
     
         7 . The film for changing the direction of light passing through the film of  claim 4 , wherein each of the bodies comprises three interconnected sides include two sides angled inward at angles of less than 60 degrees and an upper planar side that is substantially parallel to the film and disposed between the two angled sides. 
     
     
         8 . A method for determining an optimal structure on a film that changes a direction of light passing through the film, the method comprising:
 receiving a first set of parameters that define characteristics for a first structure;   generating a first model of the first structure based on the first set of parameters;   performing a first ray tracing on the first model;   determining a first attribute for light that passes through the first structure based on the first ray tracing;   receiving a second set of parameters that define characteristics for a second structure;   generating a second model of the second structure based on the second set of parameters;   performing a second ray tracing on the second model;   determining a second attribute for light that passes through the second structure based on the second ray tracing;   comparing the first attribute to the second attribute; and   selecting one of the first set of parameters and the second set of parameters based on the comparing.   
     
     
         9 . The method for determining the optimal structure on the film that changes the direction of light passing through the film of  claim 8 , wherein the first ray tracing and the second ray tracing are performed over a range of incidence angles. 
     
     
         10 . The method for determining the optimal structure on the film that changes the direction of light passing through the film of  claim 9 , wherein the range of incidence angles is a range of angles selected from the range of negative 80 degrees to positive 80 degrees as measured from an orthogonal plane passing through the film. 
     
     
         11 . The method for determining the optimal structure on the film that changes the direction of light passing through the film of  claim 9 , wherein the range of incidence angles is a range of angles selected from the range of negative 20 degrees to positive 20 degrees as measured from an orthogonal plane passing through the film. 
     
     
         12 . The method for determining the optimal structure on the film that changes the direction of light passing through the film of  claim 9 , wherein tracing is performed a predetermined number of times evenly spaced throughout the range of incidence angles. 
     
     
         13 . The method for determining the optimal structure on the film that changes the direction of light passing through the film of  claim 9 , wherein tracing is performed at each degree between the range of incidence angles. 
     
     
         14 . The method for determining the optimal structure on the film that changes the direction of light passing through the film of  claim 9 , wherein tracing is performed at each 0.5 degrees between the range of incidence angles. 
     
     
         15 . A sheet for refracting light striking the sheet, the sheet comprising:
 a substrate; and   a plurality of structures on a side of the substrate,   wherein the structures refract light that strike the structures, and   wherein each of the structures comprises a body formed of substantially transparent material.   
     
     
         16 . The sheet for refracting light striking the sheet of  claim 15 , wherein the substrate comprises a substantially polymeric material. 
     
     
         17 . The sheet for refracting light striking the sheet of  claim 15 , wherein each of the bodies is an elongated shape with a semi-circular cross section. 
     
     
         18 . The sheet for refracting light striking the sheet of  claim 15 , wherein each of the bodies is a hemispherical shape with a base supported on the substrate. 
     
     
         19 . The sheet for refracting light striking the sheet of  claim 15 , wherein each of the bodies is a pyramid shape with a base supported on the substrate. 
     
     
         20 . The sheet for refracting light striking the sheet of  claim 15 , wherein each of the bodies is a frustoconical shape with a base supported on the substrate. 
     
     
         21 . The sheet for refracting light striking the sheet of  claim 15 , wherein the sheet comprises a light receiving surface spaced apart from the substrate, the light receiving surface being sinusoidal when viewed from an edge of the sheet.