This paper reviews the literature regarding the inherent limitations of Modeling practices for sustainable energy planning in the Global South (GS).GS is undergoing economic changes in its energy-setting socio-economic policies such as liberalisation, financial sourcing, and climate change implications of energy projects. Long-term energy planning lays the foundations for effective policies, investment strategies, and targets at the national or regional level. An astute and up-to-date master plan for energy development fosters predictable investment conditions. This makes it an essential prerequisite for scaling up renewable energy technologies. Active energy planning, built on quantitative setting Modeling and stakeholder consultations, allows policymakers to understand and explore the complexities and uncertainties of future energy system evolution. Modeling and simulation (M&S) is a well-known scientific technique that could analyse a system or predict its behaviour before physical construction. Despite being an established methodical tool in engineering, only a few review articles discussing emerging topics in M&S are available in the open literature, especially for renewable and sustainable energy systems. The International Renewable Energy Agency (IRENA) offers energy planning Support, as a guide, with a view to enhancing institutional capacity at the country level and strengthening each country’s ownership of the planning process. The capacity to interpret key energy data into strong energy planning enables nations to develop all-inclusive national energy master plans and to frequently update these as the basis for comprehensive policies and investments. This paper examines the current Modeling and simulation of the energy sector with insights into the approaches, challenges, and prospects of certain selected and suitable energy systems. Additionally, it reveals the limitations of traditional planning tools such as optimisation, econometric, and general simulation models. The paper posits that traditional approaches are inadequate for SED in the GS due to its inherent weakness in guiding future policy decisions. In this work, the 7th SDG: Affordable and Clean Energy, is brought into focus. The paper addresses the Planning approaches, tools, framework, and techniques as revealed in the literature on energy Modeling and policy formulation. The aim is to enhance the country's capacity to analyse energy data and develop scenarios using Modeling tools for long-term energy planning. The additional tools to support energy planning may be selected according to each country’s needs and existing Modeling expertise. Finally, areas that need further research and development in sustainable energy Modeling are highlighted. Keywords: Sustainability, Energy Planning, Modelling, Global South. Proceedings Citation Format Abraham Rasheed Adeyemi (2023): Sustainable Energy Planning and Modelling for Global South: A Case Study of the Federal Republic of Nigeria.. Proceedings of the 37th iSTEAMS Multidisciplinary Cross-Border Conference. 30th October – 1st November, 2023. Academic City University College, Accra, Ghana. Pp 93-106. dx.doi.org/10.22624/AIMS/ACCRACROSSBORDER2023V2P8