Tiled solar cell laser process

Abstract

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.