Thermal control to maximize photovoltaic powered reverse osmosis desalination systems productivity

Photovoltaic-powered reverse osmosis (PV/RO) is a practical method for desalinating water, especially for many small, remote, off-grid communities. It is shown here that thermal control can increase its productivity, making it more economically attractive. A solar panel produces more power at lower cell temperatures and an RO unit produces more fresh water for a given power with increasing water temperature. These complementary behaviors are exploited by cooling the solar panel using the RO feed water, which warms the water. Cooling the solar panel also permits the use of concentrating mirrors, which further increases system production. The control must also prevent overheating of the panel and the RO unit, and to balance the pressures in the system. Here, a controller is designed to meet these objectives. The effectiveness of controller design is verified in simulation and experiment.

► In the presented PV/RO system, the PV panels are cooled by the RO feed water, which warms as a result. ► Cooling the PV panels permits the addition of concentrating mirrors. ► PV panel and RO water temperatures are controlled to increase clean water produced. ► A 59% increase in water production is achieved experimentally.