This paper proposes an innovative desalination technology for sustainable off-grid systems taking advantage of complementary features of tidal range and solar PhotoVoltaic (PV) energies. According to the literature survey, this proposal has not been considered before. Since fresh water production can be easily stored, the key issue in designing SeaWater Reverse Osmosis (SWRO) desalination plants is to minimise the capital cost required per m3 of fresh water produced throughout the plant lifetime. In addition, water cost of renewable energy - driven desalination strongly depends on decisions concerning battery capacity and nominal power installed, thus hybrid systems play and important role in this regard. The energy analysis performed quantifies the temporal complementarity of tidal and solar resources in an exemplary case study of a semiarid plant location at Broome, Australia. An estimation of the yearly energy production profile of the tidal range power plant is calculated with a zero-dimensional numerical model whereas the System Advisor Model (SAM) is used for the solar PV plant. The main result obtained is the great temporary complementarity of tidal and solar photovoltaic resources for SWRO application. For a given size of the PV generator the inclusion of the tidal range power plant implies an increase of the operating time of the desalination plant at nominal capacity between 1.8 and 2.8 times compared to the only solar PV driven case. This result depends on the SWRO nominal capacity. The recommended design for the case study consists in off-grid desalination plants, with minimum battery capacity if any, powered by a hybrid energy system with a ratio of installed desalination capacities of 55·103 m3/d per each hydraulic turbine of 10 MW. This system can be operated at full load a 42% of the year maximizing the yearly fresh water production.