Int. J. Renew. Energy Dev. 2023, 12 (2), 348-365 | 348 https://doi.org/10.14710/ijred.2023.49814 ISSN: 2252-4940/© 2023.The Author(s). Published by CBIORE Contents list available at IJRED website International Journal of Renewable Energy Development Journal homepage: https://ijred.undip.ac.id Comparison of the Grid and Off-Grid Hybrid Power Systems for Application in University Buildings in Nigeria Chidiebere Diyoke a , Marcel Onyekachi Egwuagu a , Thomas Okechukwu Onah a , Kenneth Chikwado Ugwu b , Eberechukwu Chukwunyelum Dim a a Department of Mechanical Engineering, Enugu State University of Science and Technology, PMB 01660. Agbani, Enugu State, Nigeria b Department of Agricultural and Bioresource Engineering, Enugu State University of Science and Technology, PMB 01660. Agbani, Enugu State, Nigeria Abstract. The Nigerian Universities rely on weak and unreliable fossil-based electric grids with diesel engine generators (DEG) as a backup. However, there is a potential to light up the campuses using power systems derived from primary renewable power systems (RPS) like wind turbine (WT) and solar photovoltaic (PV), that can be on or off-grid to improve the energy mix and duration reliably. This study presents the comparative analysis of the optimal hybrid grid and off-grid systems (OGS & OOGS) for serving the demand load of university buildings in four climatic regions of Nigeria. HOMER Pro is used to design and select the systems based on minimal net present cost (NPC) and cost of electricity (COE). The impact of a minimal renewable fraction of 95% on the optimal system architecture (OSA) and COE is studied for both grid and off-grid modes. Also, sensitivity analysis of the impact of key variables on performance for the sites is carried out. It is found that the OGS in the four regions is PV/Converter (Conv), while for the OOGS, it is PV/WT/DEG/battery (BB)/Conv except in Port Harcourt (PH), where it is PV/DEG/BB/Conv. The COE for the OGS in the Savana and monsoon climes of Enugu and PH are 10 and 19% more than that in the warm-semi arid climate zones of Maiduguri and Kano, which is approximately 0.09 $/kWh. The COE ($/kWh) for the OOGS is 0.21 in Maiduguri, 0.245 in Kano, 0.275 in Enugu and 0.338 in PH. An obligatory 95% RF changes the architecture and increases COE in all the locations except Maiduguri, with a slightly improved COE but higher NPC like other locations. It is established that the suggested hybrid system is beneficial and feasible for supplying more reliable and clean energy to educational buildings in different Nigerian locations. Keywords: Renewable energy; Electric load; Nigeria energy resources; Techno-economic analysis; Hybrid system @ The author(s). Published by CBIORE. This is an open access article under the CC BY-SA license (http://creativecommons.org/licenses/by-sa/4.0/). Received: 26 th Oct 2022; Revised: 28 th Dec 2022; Accepted: 28 th January 2023; Available online: 10 th Feb 2023 1. Introduction Energy is the driving force for economic progress and improvement in the living standards in a nation, particularly the developing ones. It can likewise be used to increase a country's productivity indicators, including education and research output. Thus, a steady and quality electricity supply is necessary to aid sustainable development. Nigeria suffers from severe electricity poverty, with a significant gap between demand and supply. Whereas the highest demand is projected to be 24 GW, the capacity of installed generators stands at about 12 GW while the electric grid is only able to dispatch about 5 GW daily, which is insufficient for a country of over about 200 million people (USAID 2022). Thus most of the homes, industries, businesses and universities in Nigeria receive an electricity supply of about 50%, far less than their demand (Diyoke, Ngwaka, & Onah, 2021). Quality education is key to a country's national development and modernization, and every nation can only develop within the quality of its educational system. Thus Nigerian Academies and other research establishments deserve special consideration in terms of access to quality and reliable electricity, among others. It is miserable to note that although the management of Nigerian universities expends a huge chunk of their annual budget on monthly energy bill payments, accessibility to a steady electricity supply in educational establishments in Nigeria which is an essential commodity for effective learning, research, institutional operation and student residency has continued to be irregular and erratic (REA undated). When obtainable, the electric supply is usually of low voltage, thus threatening some extremely delicate teaching and research equipment produced in accordance with the contemporary microelectronic age (Vanguard, 2018). Consequently, various departments in Nigerian universities resort to using ineffective, costly, polluting and very noisy petrol and diesel generating sets to supply their energy requirements. The energy demand in Nigeria, including its university sector, will continue to grow due to increasing urbanisation, development and population explosion (Adewuyi et al., 2020). It is projected that the electricity demand will surge 16.8 times by 2030. There are other estimates that put the predictions for 2025 and 2030 at 77.5 GW and 119.2 GW, respectively (Netherlands Enterprise Agency, 2021). Power supply availability and reliability in the country and the nation's institutions of learning can be improved by deploying microgrid power systems (MPS). An MPS is a self- sufficient energy system that uses distributed generation (DG) energy sources to supply electricity to a distinct geographical footprint like a college campus, hospital complex, business Research Article * Corresponding author Email: chidiebere.diyoke@esut.edu.ng (C. Diyoke)