A desalination plant, includes a sea water intake, a desalination unit having a reverse osmosis or a thermal desalination unit, a fresh water outlet and a brine outlet. The plant also includes a salinity gradient power unit having a brine inlet, a seawater inlet and a mixed water outlet. The brine outlet is connected to the brine inlet and the salinity gradient power unit is arranged to generate an electrical current. A solar power heater is between the brine outlet and the brine inlet. A method for reducing the power consumption of a desalination plant providing fresh water and brine from sea water, includes a first step of providing a salinity gradient power unit, a next step of feeding the salinity gradient power unit with brine from the desalination plant as high salinity feed and sea water as low salinity feed. A subsequent step heats the brine with solar power prior to feeding the brine to the salinity gradient power unit, followed by the steps of generating an electrical current in the salinity gradient power unit and using the electrical current as an energy source for the desalination plant.