Metallization and stringing for back-contact solar cells
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 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 roller downstream from the wire support;
a welder comprising a laser positioned such that a laser beam passes through the roller 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, the roller transparent to the laser beam; and
a cutter to sever every other one of the conductive wires between each adjacent pair of the solar cells.
2 . The system of claim 1 , wherein the wire support comprises a grooved roller to align the conductive wires substantially parallel to a first edge of each of the plurality of solar cells.
3 . The system of claim 1 , wherein the wire support comprises a reed to align the conductive wires substantially parallel to a first edge of each of the plurality of solar cells.
4 . The system of claim 1 , further comprising:
a second cutter downstream from the cutter.
5 . The system of claim 4 , wherein the second cutter is to sever all of the conductive wires at an end of a solar string.
6 . The system of claim 1 , wherein the cutter is downstream from the welder.
7 . The system of claim 1 , wherein the cutter is vertically beneath the welder.
8 . A system for electrically coupling solar cells, the system configured to perform a 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, and wherein aligning the conductive wires comprises using a wire support included in the system;
bonding the conductive wires to the back side of each of the solar cells over the P-type and N-type doped diffusion regions, wherein bonding the conductive wires comprises using a laser welder and a roller included in the system, the laser welder downstream from and vertically beneath the wire support in the system, wherein the laser welder comprises a laser positioned such that a laser beam passes through the roller, the roller transparent to the laser beam;
subsequent to bonding the conductive wires to the backside of each of the solar cells, cutting every other one of the conductive wires between each adjacent pair of the solar cells, wherein cutting every other one of the conductive wires comprises using a first cutter included in the system, the first cutter downstream from the laser welder in the system; and
subsequent to cutting every other one of the conductive wires, severing all of the conductive wires at an end of a solar string, wherein severing all of the conductive wires comprises using a second cutter included in the system, the second cutter downstream from the first cutter in the system.
9 . The system of claim 8 , wherein aligning the conductive wires comprises aligning the conductive wires substantially parallel to a first edge of each of the plurality of solar cells.
10 . The system of claim 8 , 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.
11 . The system of claim 8 , 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.
12 . The system of claim 8 , wherein the electrically coupled solar cells form a string of solar cells, the method performed by the system 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.
13 . The system of claim 12 , 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.
14 . The system of claim 8 , wherein the method performed by the system further comprises 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.
15 . The system of claim 8 , 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 included in the system.