Performance evaluation and economics of a locally-made stand-alone hybrid photovoltaic-thermal brackish water reverse osmosis unit

The performance of a developed brackish water reverse osmosis (BWRO) desalination unit integrated with a stand-alone hybrid photovoltaic-thermal (PVT) module was evaluated under the climatic conditions of Tehran (35.68 degrees N latitude 51.42 degrees E longitude). From the experimental results, the maximum surface temperature of the PV module and thermal efficiency of the PVT module were recorded as 60.38 degrees C and 83.7%, respectively at the set-point temperature of 50.00 degrees C for the thermostat, and under the average solar radiation of 971.34 W/m(2). During the evaluation, the maximum average productivity of the BWRO unit was obtained as 13.98 L/h when temperature values of the PV module, soft water, and brackish feed water (BFW) were recorded as 52.94 degrees C, 28.97 degrees C, and 36.60 degrees C, respectively. From the results, it was also found that the temperature of BFW positively affects the PVT module's thermal performance and improves the whole unit's productivity. Also, water quality parameters of pH, TDS, EC, and DO for treated water were evaluated. The economic analysis of the system revealed that the cost of the produced freshwater for the BFW's salinity of 15,000 ppm is 18.96% higher in comparison with 5000 ppm for all cases, indicating a closer value to freshwater cost of conventional large-scale RO plants.