The availability of fresh water in arid regions like Jordan presents a critical challenge that requires solutions benefiting from available renewable resources in the region to develop sustainable and efficient solutions. This study presents a modernization of an existing solar-powered reverse osmosis (RO) desalination system located in the Jordan Valley, which has been operating for more than 12 years. The modification is achieved by increasing the available membrane area and utilizing the residual pressure in the system which is augmented by a booster pump by two bars approximately. For that, two additional membranes have been installed in the existing system which has three membranes. Significant performance improvements have been achieved, including a 25% increase in freshwater production, reduction of specific energy consumption from 2.2 to 1.8 kWh/m3, and a decrease in electrical conductivity of produced water from about 140 & micro;S/cm to below 90 & micro;S/cm considering the same feed water and weather conditions. The new modified system demonstrates retrofitting an ageing solar-driven RO unit to enhance water supply for irrigation providing a cost-effective and environmentally sustainable solution for freshwater scarcity in agricultural arid regions.