Experimental determination and modelling of a PV module with evaporative cooling for hybrid power generation and distilled water production

This research developed a model from experimental data for predicting electrical performance and rate of distilled water production using a photovoltaic (PV) module with evaporative cooling. The model required information of solar radiation incident upon the module, the ambient temperature, the module’s surface area, the mass flow rate and temperature of water entering the cooling pad as well as the nominal operating cell temperature (NOCT). Experiments were performed with a module having an area of 1.94 m2, attached with 5-mm thick cellulose-polypropylene at the rear surface. Moreover, water feed into the pad was controlled at a temperature of 26-28 ℃ and a fixed flow rate of 0.25 L/min to assure that the pad was fully wetted. The solar heat absorbed by the module could be used to generate water vapor from the pad, which was then condensed on a frame underneath. The experimental data showed that the NOCT was reduced to 43 ℃ from 48 ℃ for an unmodified unit. With evaporation and condensation of water vapor, the PV module could generate more electrical energy, and the unit could also produce distilled water at a mass rate that depended linearly on the difference between the PV module and ambient temperatures. The simulation indicated a strong correlation with the actual test results on both clear sky and cloudy days. Additionally, monthly and yearly performances were simulated in three cities, Chiang Mai with its tropical savanna climate, Sihanouk Ville with a tropical climate, and Ouargla with a tropical desert climate. In relation to solar radiation levels, the highest net annual electrical energy was observed in Ouargla, followed by Sihanouk Ville and Chiang Mai, 806.12, 691.59 and 676.20 kWh, respectively. Annual yields of distilled water were 523.44, 460.48, and 372.52 L/y for Sihanouk Ville, Chiang Mai and Ouargla, respectively.