Photovoltaic Powered Reverse Osmosis Plant for Brackish Water without Batteries with Self Acting Pressure Valve and MPPT

Abstract

This paper presents a PV (photovoltaic) powered RO (reverse osmosis) plant for brackish water without batteries and a self-regulating pressure valve. The aim is to extract the maximum power from the PV module using an MPPT (maximum power point tracking) technique for powering a solar water pump and maintain constant the pressure in the RO membranes by using the self-operated valve. A Buck type converter using the InCond (incremental conductance) MPPT was developed for this application. The MPPT chosen was simulated, tested and validated, showing an efficiency of 86.8%. The technical feasibility of the RO plant was made by PLC (programmable logic controller) and was tested for two salinity levels (1,000 and 1,500 mg/L of TDS (total dissolved solids)). These salinity levels chosen are commonly found in most brackish water wells of the semi-arid region of Northeastern Brazil. The RO plant could permeate 175.3 L/day of drinking water with 120 mg/L of TDS and specific energy consumption of 2.56 kWh/m 3 .