A sustainable solution to provide fresh drinking water was studied in this paper. A very small batch-ED (electrodialysis) unit fed by a PV (photovoltaic) array was tested to desalt brackish water. The main novelty in the PV generator proposal is its flexibility to change the operating conditions by changing the number of connected cells. The ED unit could also be connected to the grid by means of a controlled rectified. First, the ED-stack model was implemented and experimentally validated. Then, several analyses of the main features of the on-grid and the off-grid connection were performed to further optimize both energy supplies. Very competitive SEC (specific energy consumption) was obtained for brackish water solutions of about 3000 ppm: 1 kWh/m3. An alternative solution to the point of MPPT (maximum power point tracker) was presented here to operate the PV array. Thus, ED–PV combination could not only suppose a clean but also a low maintenance water source for arid and isolated areas in the next future.