**1. Introduction**

The photovoltaic industry plays a critical part in the global energy scenario [1] to compete with the other renewable and conventional energy sources. Crystalline silicon (c-Si) wafer-based technologies [2, 3] dominate the photovoltaic market for terrestrial application due to its high efficiency, stability, and benefits arising out of microelectronic industry. Due to high production cost (i.e., high \$/watt), researchers are continuously putting their efforts to improve low cost Si solar cell technology. Silicon solar cell fabrication process involves various vital steps [4, 5] which includes texturing [6], n+ and p+ diffusion [7, 8], antireflection coatings [9], and contact metallization [7–15]. Electrical parameters of the solar cell, namely open circuit voltage (Voc), short circuit current (Isc), and fill factor (FF) vary with processing conditions. Though the conventional Si processing technology is mature, it is important to modify fabrication process and device structure to improve electrical performance. Approaches such as nickel/copper metallization in conventional solar cell structure [16–18], passivated emitter rear contact (PERC) cells [19] and interdigitated back contacts (IBC) cells [20], etc. are being used in lab scale and production. In this chapter, contact mechanism in conventional structure and novel structures is reviewed.
