Solar Photovoltaic system comprises of photovoltaic (PV) array, converter, inverter and battery storage unit of appropriate capacity to serve the load demand in reliable, efficient and economically feasible manner. The proper selection of technology and size of these components is essential for stable and efficient operation of PV system. Therefore, a number of modeling equations and methodologies for designing a PV system based on application have been developed in order to ensure the optimum performance of the PV system. In this paper, a comprehensive designing process of solar photovoltaic water pumping system, standalone PV system and grid connected PV system is presented. The modeling of PV modules, cell temperature, water pumping system and battery state of charge is tabularized so as to facilitate their utilization for proposing a PV system based on the techno-economic variables and environmental parameters. The financial and reliability parameters for techno-economic size optimization of PV system are also identified and different optimization techniques have been discussed. A state of art literature survey has been presented which is useful in designing and installation of solar PV systems for standalone as well as grid connected power supply.