A Plant for trigeneration of freshwater, power and cooling has been developed and optimized for higher efficiency and lower plant cost. Parabolic trough collectors with thermal energy storage are considered using thermal oil as the heat transfer fluid. Solar heat is utilized to produce power via a Toluene-based Rankine cycle for power generation and cooling via an Absorption chiller. A part of the generated power is used to run a Reverse Osmosis desalination plant. The solar data is taken from a southern city in Turkey. Exergy efficiency and plant cost rate of the system vary between 9-14% and 287-335 $/h, respectively. A multiobjective optimization study depicts that optimal exergy efficiency of %12.5 is obtainable at a plant cost rate of 328 $/h. Freshwater cost is strongly dependent on the cost of solar electricity and shows a significant fluctuation due to variable solar availability condition. The results of the studied system depict that sustainable and economical plant operation is possible in short/near terms when the investment costs of utilized technologies are competitive with those used in conventional plants.