Solar energy is a renewable source of energy which can meet all the energy requirements on the earth, if properly utilized. Two different ways of utilizing solar energy is photovoltaic and solar thermal technologies. Photovoltaic (PV) power generation has become one of the booming fields that are capable of bridging the gap between supply and demand to meet the current energy crisis. There are two major factors affecting the output power of a photovoltaic panel - cell temperature and solar radiation absorbed. An efficient way to increase the output power is to increase the amount of radiation received by the PV panel. The intensity of sun’s radiation varies throughout the day, month and year due to motion of earth around the sun and its own axis. The concept of optimal tilt paves way to check the impact of solar radiation reaching the surface of PV panel. This paper reviews various research works, both experimental and modeling types, carried out across the globe to determine the optimal tilt.