Solar Energy Hybrid System for Seawater Distillation in the Coastal Regions

Coastal regions and small islands in the open sea areas are commonly poor in fresh-water resource availability. Because of its high-level of hardness, the seawater is in general not much used for everyday life. In tropical countries like Indonesia, the daily duration of solar irradiation throughout the year does not vary much, with an average of about 12 hours a day. The solar energy can be used to evaporate seawater and to produce fresh-water coming from the steam condensation through a distillation process. It is shown in this research that using a hybrid system the fresh-water production can be extended to the period when the solar radiation is insufficient, so that the solar energy usage can be maximized. It can be used for heating the seawater directly in an evaporating house while being used at the same time to produce electricity using solar cells. As the voltage generated by the solar cells was not of constant value depending on the incident irradiation, a cuk converter being operated based on the Pulse-Width Modulation (PWM) principle has been used to stabilize the voltage fed into a battery at 15V-level. It was furthermore used to supply the heating system after being inverted into an AC voltage waveform. It would be functioning when the solar irradiation was not sufficient to evaporate the seawater directly. The internal temperature of the evaporating room was known using a sensor PT100. The sensor data needed to be conditioned before being processed furthermore in a microcontroller Arduino Uno. After reaching the desired temperature setting point, a relay circuit module would operate to cut off the current and to turn on/off the heating system. The generated steam has been passed through a condenser to produce the fresh-water. The results of the study showed that an amount of 3.5 litres of seawater being evaporated during 10 hours would produce 1.076 litres of fresh-water using a total power of 184.06W.