The overall objective of the MEDIRAS project is the development and demonstration of cost effective and very reliable solar driven desalination systems for water scarcity affected regions with high insolation. The modular system set up is based on the highly innovative Membrane Distillation (MD) technology. MD is favorably applicable for small distributed desalination systems in the capacity range between 0.1-20m³/day. MD is very robust against different raw water conditions and operable with alternating energy supply like solar energy. With respect to demonstration and market penetration of MD systems, the project will be focused on cost reduction and quality improvement for life time extension of MD modules and MD systems, on the development of components such as brine cooler and brine disposal units for ground water desalination at inland locations with limited raw water resources, and on the development of scalable system configurations in order to adapt them to different customer demands. Solar energy driven units for potable water disinfection will be integrated into the desalination units for health protection. The emphasize of the MEDIRAS project is on the design, set up and operation of different demonstration systems. Three compact systems of different sizes (150l/day and 300l/day) and two multi module two loop systems (3m³/day and 5m³/day) for full solar energy supply and for combined solar and waste heat energy supply will be installed in different European potential user sites in , Gran Canaria (Spain), Tenerife (Spain) and Pantelleria (Italy), as well as in Tunesia as an example for an North-African country. Comprehensive performance evaluation and water quality analyses will be conducted. With respect to market penetration in addition to the technological goals, focus will also be on the identification of suitable markets and target user-groups for the technology and the preparation of the conditions for the system to enter the identified markets.