Wet chemical etching of solarcell for edge isolation

Abstract

Solar Energy as an alternative for conventional resources is getting popular day by day. As fossil energy sources diminishing gradually and some of them have adverse effects on world climate. One of the most popular methods, now a day for harnessing solar energy is solar panel. Solar cell depends upon the photovoltaic effect for their operation. The efficiency of solar cell depends upon how much energy input of solar energy is converted as output current. Solar cell efficiency also dependent upon some characteristic parameters such as short circuit current (Isc), open circuit voltage (Voc) and fill factor (FF). Parasitic components affect these parameters. These resistive parameters are series and shunt resistances. Shunt in solar panel is a loss mechanism occurs due to defects. Volume shunts are material induced shunts can occur due to impurities, metal particles contamination or aluminum particle contamination while making grid fingers, are impossible to eradicate without destroying the cell. On the other hand, mostly occurred edge shunts due to crack, holes or scratches can be removed in many available techniques. During the manufacturing of solar cell, a very important step called edge isolation process affects IV characteristics of solar cell, which is critical to the efficiency of itself. Deep and crack-free edge isolation to increase shunt resistance in the solar cell achieves higher efficiency and eliminates the source of fatigue cracks to extend lifespan of solar cells. There are many techniques available for removing shunts. In this paper, wet chemical etching method by HNA, is used for edge isolation process. From the experiments results it is found that HNA etching improves the IV characteristics of solar cells and hence it improves the power curves. Efficiency of un-etched solar cells was 3.17% and 3.90%. After etching the solar cell efficiency increase up to 5.53% and 5.31% respectively. From these progressive results, it can be said that wet chemical etching has flawless demands for further study.