TILED SOLAR CELL LASER PROCESS
In an example, the present invention provides a method of separating a photovoltaic strip from a solar cell. The method includes providing a solar cell, placing the front side of the solar cell on a platen such that the backside is facing a laser source, initiating a laser source to output a laser beam having a wavelength from 200 to 600 nanometers and a spot size of 18 to 30 microns, subjecting a portion of the backside to the laser beam at a power level ranging from about 20 Watts to about 35 Watts to cause an ablation to form a scribe region having a depth, width, and a length, the depth being from 40% to 60% of a thickness of the solar cell, the width being between 16 and 35 microns to create a plurality of scribe regions spatially disposed on the backside of the solar cell.
1 . A method comprising:
providing a solar cell comprising either a single crystalline silicon material or a polycrystalline solar cell, the solar cell having a backside and a front side and a thickness, the backside having a metal material;
placing the front side of the solar cell on a platen such that the backside is facing a laser source;
initiating a laser source to output a laser beam;
subjecting a portion of the backside to the laser beam to cause an ablation to form a V-shaped scribe region having a depth, width, and a length, the depth being from 40% to 60% of the thickness of the solar cell, and the length being equivalent to a length of the solar cell;
removing a vaporized material from a vicinity of the ablation;
capturing the vaporized material using a vacuum; and
applying mechanical stress to initiate a crack defining a fracture plane in the solar cell.
2 . The method of claim 1 wherein removing the vaporized material comprises subjecting a fluid, using a laminar flow, within the vicinity of the ablation.
3 . The method of claim 2 wherein the fluid comprises air.
4 . The method of claim 1 wherein removing the vaporized material comprises delivering a jet of fluid to the vicinity of the ablation.
5 . The method of claim 1 further comprising removing the solar cell from a laser system prior to applying the mechanical stress to initiate the crack.
6 . The method of claim 1 wherein the scribe region is a straight line +/−10 microns.
7 . The method of claim 1 wherein the thickness is from 170 to 220 microns.
8 . The method of claim 1 wherein the depth is between about 65 and 132 microns.
9 . The method of claim 1 wherein the width is from about 15% to 40% of the depth.
10 . The method of claim 1 wherein the width is from about 7% to 20% of the thickness.
11 . The method of claim 1 wherein subjecting the portion of the backside to the laser beam comprises applying the laser beam at a repetition rate of between about 100-300 kHz.
12 . The method of claim 1 wherein subjecting the portion of the backside to the laser beam comprises applying the laser beam at a velocity of between about 4800 to 5000 mm/second.
13 . The method of claim 1 wherein subjecting the portion of the backside to the laser beam is performed at a height varying not more than +/−50 μm.
14 . The method of claim 13 wherein the width varies by 5 μm or less along the length.
15 . The method of claim 1 further comprising marking the solar cell with an identifier after forming the V-shaped scribe region.
16 . The method of claim 15 wherein the identifier is marked with the laser beam.
17 . The method of claim 1 further comprising determining a cutting parameter at which the laser beam is output.
18 . The method of claim 17 wherein the cutting parameter is selected from:
a spot location;
a focal point;
a horizontal travel velocity; and
an energy level.
19 . The method of claim 17 wherein:
the laser beam is applied in a number of passes; and
the cutting parameter comprises a repetition rate.
20 . The method of claim 17 wherein:
the laser beam is applied in a pulse; and
the cutting parameter comprises a pulse frequency.