The design of the TES system comprises two molten salts tanks.One of them contained the salt at a higher temperature (“hotetank”at 388 C) and the other one accumulated the salt at a lower temperature (“cold-tank” at 288C). The two tanks were of cylindrical shape with the same dimensions, 8 m diameter and about 6 m height (4.4 m cylindrical wall). Each tank was able to store all the salt needed in the installation by itself. The tanks were installed inside independent concrete buckets of 1 m height. The foundations, also independent, were calculated based on the results of the geotechnical study of the emplacement.