Abstracto

Development of Laser Edge Isolation Process for Industrial Solar Cells

S.R. Reddy, Rahul Prasad, Abhishek Sharan and B. Prasad

In the fabrication of crystalline (mono and multi) silicon solar cells, p-type silicon wafers are diffused with phosphorous to form large area (240 Cm2) p-n junction, which is responsible for separation of photo generated carriers. During emitter diffusion process, phosphorous diffusion also takes place over the edges and rear side of the wafer. This creates shunt paths between the front (n-type) and back (p-type) surface. These shunt paths cause reduction in solar cell efficiency. In the study presented here, Q-switched nanosecond 532 nm wavelength laser is used for isolating the shunts at the edges by scribing on either front or back side of cells. The effect of laser scribing parameters on groove characteristics is studied and optimized so as to get maximum efficiency of solar cells. From our results, we find that laser edge isolation process shows an enhancement of average output power of solar cells by 3.45% compared to the plasma edge isolation process. The laser edge isolation technique developed is suitable for inline production for industrial applications and is environment friendly as no hazardous fluorine based chemicals are used.