Concentrated solar power (CSP) is today recognized as a unique renewable energy for electricity generation due to its capability to provide dispatchable electricity incorporating thermal energy storage (TES). Molten salts TES is the most widespread technology in commercial CSP but the industry is looking for cheaper and more efficient TES systems and phase change materials (PCM) have been highlighted as potential low cost and high energy TES systems. This paper presents a completely new concept of PCM energy storage systems to be used in solar thermal electricity plants with its technical assessment. A cascade type PCM storage system is evaluated, using four buckets with the PCM organized based on melting temperature and the latent energy of the materials. Daily, monthly, and annual transient simulations of the plant performance are carried out. The main conclusion is the similarity between this new concept and the commercial two-tank indirect molten salt system. The cumulative power production over the year is similar and the net production of both systems is well matched. The work was partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER)). Dr. Cabeza would like to thank the Catalan Government for the quality accreditation given to her research group (2017 SGR 1537). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia.