High efficiency configuration for solar cell string

Abstract

A high efficiency configuration for a string of solar cells comprises series-connected solar cells arranged in an overlapping shingle pattern. Front and back surface metallization patterns may provide further increases in efficiency.

What is claimed is: 
     
         1 . An apparatus comprising:
 a plurality of rectangular or substantially rectangular silicon solar cells arranged in line with long sides of adjacent silicon solar cells overlapping and conductively bonded to each other with an electrically conductive bonding material to electrically connect the silicon solar cells in series to form a string of silicon solar cells, each silicon solar cell comprising a front surface to be illuminated by light and an oppositely positioned rear surface;   wherein the front surface of each silicon solar cell comprises:   a plurality of fingers oriented perpendicularly to the edge of a first long side of the silicon solar cell and spaced along the first long side with a pitch of about 0.7 millimeters to about 1.2 millimeters;   a bypass conductor that interconnects two or more of the plurality of fingers; and   an end conductor that interconnects two or more of the plurality of fingers at their ends opposite from the edge of the first long side of the silicon solar cell;   wherein
 for each pair of adjacent silicon solar cells in the string of silicon solar cells the electrically conductive bonding material is bonded to and electrically interconnects the fingers on the front surface of one of the pair of solar cells adjacent the edge of the first long side of the silicon solar cell to perform a current collecting function of a bus bar, 
 the bypass conductor on the front surface of the solar cell provides multiple current paths between the fingers and the electrically conductive bonding material, and 
 the end conductor provides additional current paths between the fingers and the electrically conductive bonding material. 
   
     
     
         2 . The apparatus of  claim 1 , wherein the electrically conductive bonding material is an electrically conductive adhesive. 
     
     
         3 . The apparatus of  claim 1 , wherein the electrically conductive bonding material provides more mechanical compliance than provided by an electrically conductive solder bond. 
     
     
         4 . The apparatus of  claim 1 , wherein the rear surface of each silicon solar cell that overlaps a front surface of an adjacent silicon solar cell comprises a bus bar or plurality of contact pads conductively bonded to the front surface of the adjacent silicon solar cell by the electrically conductive bonding material. 
     
     
         5 . The apparatus of  claim 1 , comprising a mechanically compliant electrical interconnect conductively bonded to the front surface of one of the silicon solar cells. 
     
     
         6 . The apparatus of  claim 5 , wherein the mechanically compliant electrical interconnect is electrically connected to a bypass diode. 
     
     
         7 . The apparatus of  claim 1 , comprising a mechanically compliant electrical interconnect conductively bonded to the rear surface of one of the silicon solar cells. 
     
     
         8 . The apparatus of  claim 7 , wherein the mechanically compliant electrical interconnect is electrically connected to a bypass diode. 
     
     
         9 . The apparatus of  claim 1 , comprising a mechanically compliant electrical interconnect conductively bonded to the rear surface of one of the silicon solar cells located at an intermediate position along the string of silicon solar cells. 
     
     
         10 . The apparatus of  claim 9 , wherein the mechanically compliant electrical interconnect is electrically connected to a bypass diode. 
     
     
         11 . The apparatus of  claim 1 , comprising another bypass conductor arranged in line with the bypass conductor and interconnecting another two or more fingers to provide multiple current paths from each of the other two or more interconnected fingers to the electrically conductive bonding material. 
     
     
         12 . The apparatus of  claim 1 , wherein the end conductor has a width perpendicular to its long axis that is the same as the width of a finger. 
     
     
         13 . The apparatus of  claim 1 , wherein the front surface of each silicon solar cell comprises a bus bar or a plurality of contact pads positioned adjacent to and running parallel to the edge of the first long side of the silicon solar cell between the bypass conductor and the edge, and for each pair of adjacent silicon solar cells in the string of silicon solar cells the electrically conductive bonding material is bonded to the bus bar or plurality of contact pads. 
     
     
         14 . The apparatus of  claim 13 , wherein the bus bar or plurality of contact pads have a width perpendicular to the edge of the first long side that is the same as the width of one of the plurality of fingers. 
     
     
         15 . The apparatus of  claim 1 , wherein the front surfaces of the silicon solar cells do not comprise bus bars or a plurality of contact pads running parallel to the edge of the first long side of the silicon solar cell between the bypass conductor and the edge. 
     
     
         16 . The apparatus of  claim 1 , wherein the ratio of the length of a long side of the rectangular or substantially rectangular silicon solar cells to the length of a short side of the rectangular or substantially rectangular silicon solar cells is greater than or equal to three. 
     
     
         17 . The apparatus of  claim 1 , sandwiched between a transparent top sheet and a glass substrate. 
     
     
         18 . The apparatus of  claim 1 , wherein the front surface of each silicon solar cell comprises about 125 to about 225 fingers spaced along the first long side.