The European Solar Telescope (EST) has completed the Preliminary Design Review (PDR) of its Single Conjugate Adaptive Optics (SCAO) system and real-time controller. We present an overview of the expected SCAO performance based on the consolidated preliminary design, including simulations of a dual-branch configuration at 500nm and 680nm. The results, obtained with the new open-source Solar Adaptive Optics Simulator (SAOS) and validated against DASP, also evaluate key error sources specific to solar observations. We summarise the performance of the proposed real-time controller, the Durham Adaptive Optics (DAO) platform, and the successful demonstration tests conducted with SAOS.