The increasing awareness of environmental concerns, coupled with the need to enhance energy security and alleviate the impacts of climate change, has fast-tracked an intensive exploration of renewable energy technologies. The development has indeed recorded a remarkable growth in most developed countries like China, USA, Brazil and China. However, this is not the same with most developing countries in Africa. This work carried out a comprehensive review of the available Renewable Energy Sources (RES) in Nigeria, assess its level of utilization, identified the challenges and suggested effective ways of ensuring adoption of decentralized energy system through the use of RES. Critical analysis of public opinions on the acceptability of RES as a decentralized energy system in the country were carried out. The work sampled the opinions of people in the adoption of RES for decentralized energy system using south west, Nigeria as a case study. The population involves power stakeholders, rural dwellers, RES experts and policymakers across the six states of the South west, Nigeria. A well-structured questionnaire was designed to capture nuanced responses on a range of key parameters, including awareness levels, acceptance, and perceived benefits and challenges associated with decentralized renewable energy systems. The research findings (through the use of questionnaires) showed a very low level of awareness and acceptability of RES, provided valuable insights on the potential barriers and possible facilitating conditions for adoption of renewable energy technologies.