A comprehensive techno-economic analysis, based on a systems concept approach, has been carried out, to study the performance and cost of integrated solar powered seawater desalination plants, named "Suryajal". In the first (technical) part of this paper, the energy requirement of a typical Seawater Reverse Osmosis (SWRO) system is estimated. Mathematical equations are developed that balances the energy input requirements of a SWRO plant to the energy output of Solar Photo Voltaic (SPV) Power plant. In the second (economic) part, a parametric study is carried out within a framework of six techno-economic operational scenarios. Regression equations are developed for SPV as well as SWRO plants. The specific capital cost trend of both SPV and SWRO plant are seen to decrease rapidly with size. The regression equations, with different financing options, are then used to analyze the trend of plant specific capital cost, and total investment required for integrated SPV-RO plants, as a function of fresh water production capacities, from 0.5 Million Litres per Day (MLD) to 300 MLD. Water costs as a function of capital cost, power cost and maintenance costs; as well as specific capital cost of integrated PV-RO plants, for different plant capacities, are estimated, with full capital cost recovery and without taking into account subsidies available for renewable energy systems. It is observed that plant specific capital cost as well as fresh water cost, fall rapidly and significantly down to current costs of river water, as plant capacity increases, for all techno-economic scenarios considered. It is concluded that seawater desalination, especially on large scales using solar photovoltaic power plants is a technically feasible, economically viable and environmentally friendly option for perennial supply of fresh water from the ocean.