This work reports the results of a feasibility study on commercial thermal energy storage systems for the temperature range between 200 and 450C with an investment cost goal of $25 per KWh thermal capacity. The most promising sensible and latent heat storage systems with 200 MWh capacity have been analyzed thermodynamically and economically for their suitability in large scale economically parabolic trough collector power plants. In the final selection a dual medium sensible heat storage system with concrete as storage medium has been optimized with respect to capacity, heat transfer and costs. Phase change systems consisting of different salt mixtures have been investigated. As a third option, active two tank storage systems with a molten eutectic salt as liquid medium were studied. Performance and costs results were summarized and compared.