Clean drinking water supplies and electric power are simultaneously produced with conventional solar panels modified by researchers from King Abdullah University of Science and Technology, Saudi Arabia. A three-stage membrane distillation system attached to the back of power-generating solar panels captures waste heat for use in vaporizing seawater.

The porous hydrophobic membranes and heat conduction layers separate a series of water channels carrying saline water. Seawater vaporized by use of waste heat condenses as clean water as the heat passes through a thermal conduction layer to be recycled in the next channel, distilling seawater in the next channel.

The off-the-shelf solar cells incorporated into the system demonstrated an 11% efficiency, and the solar distillation system produced up to 1.64 liters of water/m² of solar panel surface every hour. The technology described in Nature Communications can lower the costs of renewable electricity and freshwater supply by co-locating resources.

Schematic of a photovoltaic-membrane distillation system. A) In dead-end mode, source water is wicked into the evaporation layer in the direction of the red arrow and the condensed water flows out from the condensation layer in the direction of the green arrow. B) In cross-flow mode, source water flows to the evaporation layer in the direction of the red arrow and the condensed water flows out from the condensation layer in the direction of the green arrow through a thermal conduction layer to the next seawater channel, recycling the energy to purify more water. Source: King Abdullah University of Science and Technology