The objective of this present work was to develop, design and pilot test a small scale solar driven, high performance mechanical vapour compression (MVC) desalination unit with nano-filtration (NF) pre-treatment (Solar-NF-MVC). The system electrical and thermal energies was generated using the integration of photovoltaic (PV) and concentrated solar power (CSP) panels. CSP thermal energy was stored in a phase change material (PCM) exchanger for a start-up operation. Nano filtration (NF) membrane was used for feed water pre-treatment in order to increase the top brine temperature (TBT) up to 100°C. Therefore, the operation of the MVC unit could be at atmospheric pressure. This allowed the use of available components in the local market, besides reducing the size of the evaporator, vapour compressor, and vent ejector. Also, the unit air leakage was eliminated reducing corrosion and allowing the use of cheaper tubes material. A comprehensive mathematical model has been developed, programmed using MATLAB program, and was used as a tool for the system’s design and operational performance analysis. Predicted results were verified using the available published data of similar operating systems. Then, the model was used for the detailed design of 1.0 m3/day pilot test unit locally manufactured and tested for its different operational scenarios including both start-up and steady-state operation.