Metallization and stringing for back-contact solar cells

Abstract

Metallization and stringing methods for back-contact solar cells, and resulting solar cells, are described. In an example, in one embodiment, a method involves aligning conductive wires over the back sides of adjacent solar cells, wherein the wires are aligned substantially parallel to P-type and N-type doped diffusion regions of the solar cells. The method involves bonding the wires to the back side of each of the solar cells over the P-type and N-type doped diffusion regions. The method further includes cutting every other one of the wires between each adjacent pair of the solar cells.

1 . A string of solar cells comprising:
 a plurality of back-contact solar cells, wherein each of the plurality of back-contact solar cells comprises alternating P-type and N-type doped diffusion regions; and   a plurality of conductive wires disposed over a back surface of each of the plurality of solar cells, wherein each of the plurality of conductive wires is substantially parallel to the P-type and N-type doped diffusion regions of each of the plurality of solar cells;   wherein every other one of the plurality of conductive wires is cut in a region between each adjacent pair of the plurality of solar cells.   
     
     
         2 . The string of solar cells of  claim 1 , wherein each of the plurality of solar cells is substantially rectangular, and wherein the P-type doped diffusion regions, the N-type doped diffusion regions, and the plurality of conductive wires are substantially parallel to a first edge of each of the plurality of solar cells. 
     
     
         3 . The string of solar cells of  claim 1 , wherein each of the plurality of solar cells is substantially rectangular, and wherein the P-type doped diffusion regions, the N-type doped diffusion regions, and the plurality of conductive wires are disposed at a non-zero angle relative to edges of each of the plurality of solar cells. 
     
     
         4 . The string of solar cells of  claim 3 , wherein the P-type doped diffusion regions, the N-type doped diffusion regions, and the plurality of conductive wires are disposed at an angle in a range of 1 to 25 degrees relative to edges of each of the plurality of solar cells. 
     
     
         5 . The string of solar cells of  claim 1 , wherein a given cut section of wire of the plurality of conductive wires is to electrically couple at most two solar cells together in series, wherein the P-type doped diffusion regions of one of the two solar cells is connected to the N-type doped diffusion regions of the other of the two solar cells. 
     
     
         6 . The string of solar cells of  claim 1 , further comprising:
 a conductive busbar at an end of the string of solar cells, wherein the conductive busbar is electrically coupled with every other one of the plurality of conductive wires, and wherein the conductive busbar is to electrically couple the string with another string of solar cells.   
     
     
         7 . The string of solar cells of  claim 6 , wherein a cut section of wire of the plurality of conductive wires that is to electrically couple the end of the string of solar cells to the conductive busbar is to couple a single solar cell to the conductive busbar. 
     
     
         8 . The string of solar cells of  claim 1 , wherein a number of the plurality of conductive wires is equal to a number of diffusion regions of each of the plurality of solar cells. 
     
     
         9 . The string of solar cells of  claim 1 , further comprising non-conductive shields disposed between and coupling back sides of each adjacent pair of the plurality of solar cells. 
     
     
         10 . The string of solar cells of  claim 9 , wherein the non-conductive shields cover exposed sections of the plurality of conductive wires between each adjacent pair of the plurality of solar cells. 
     
     
         11 . A method of electrically coupling solar cells, the method comprising:
 aligning conductive wires over back sides of adjacent solar cells, wherein the conductive wires are aligned substantially parallel to P-type and N-type doped diffusion regions of the solar cells;   bonding the conductive wires to the back side of each of the solar cells over the P-type and N-type doped diffusion regions; and   cutting every other one of the conductive wires between each adjacent pair of the solar cells.   
     
     
         12 . The method of  claim 11 , wherein aligning the conductive wires comprises aligning the conductive wires substantially parallel to a first edge of each of the plurality of solar cells. 
     
     
         13 . The method of  claim 11 , wherein aligning the conductive wires comprises aligning the conductive wires at a non-zero angle relative to edges of each of the plurality of solar cells, wherein the P-type doped diffusion regions and the N-type doped diffusion regions are at the non-zero angle relative to edges of each of the plurality of solar cells. 
     
     
         14 . The method of  claim 11 , wherein cutting every other one of the conductive wires comprises cutting the conductive wires to electrically couple at most two solar cells together in series with a given cut section of wire, wherein the given cut section of wire is to connect the P-type doped diffusion regions of one of the two solar cells to the N-type doped diffusion regions of the other of the two solar cells. 
     
     
         15 . The method of  claim 11 , wherein the electrically coupled solar cells form a string of solar cells, the method further comprising:
 electrically coupling a conductive busbar with each wire bonded to an end solar cell of the string;   cutting every other one of the conductive wires between the conductive busbar and the end solar cell; and   electrically coupling the conductive busbar with another string of solar cells.   
     
     
         16 . The method of  claim 15 , wherein cutting every other one of the conductive wires between the conductive busbar and the end solar cell comprises electrically coupling a single solar cell of the string of solar cells with the conductive busbar. 
     
     
         17 . The method of  claim 11 , further comprising attaching a non-conductive shield to back sides of the solar cells between each adjacent pair of the solar cells, hiding exposed sections of the conductive wires when viewed from front sides of the solar cells. 
     
     
         18 . The method of  claim 11 , wherein cutting the every other one of the conductive wires between each adjacent pair of the solar cells comprises cutting the every other one of the conductive wires with a laser or blade. 
     
     
         19 . A system for electrically coupling solar cells, the system comprising:
 a wire support to align conductive wires substantially parallel with P-type and N-type doped diffusion regions of each of the solar cells;   a welder to bond the conductive wires to the back side of each of the solar cells over the P-type and N-type doped diffusion regions; and   a cutter to sever every other one of the conductive wires between each adjacent pair of the solar cells.   
     
     
         20 . The system of  claim 19 , wherein the wire support comprises a grooved roller or a reed to align the conductive wires substantially parallel to a first edge of each of the plurality of solar cells.