PREP-EST is a project funded by the Canary Islands Government under a direct grant awarded on grounds of public interest. The objective of PREP-EST is the realization of the preliminary design of systems and subsystems of the telescope to a sufficient level that allows starting the detailed design stage and, in a next phase, the beginning of the construction of the EST in compliance with its scientific requirements. These tasks will take into account the conceptual design study (DS-EST), and also the main results achieved in SOLARNET, GREST and in the project in progress PRE-EST.