Design of an off-grid hybrid PV/Wind/DG power system for remote mobile base station (Case study around Bale- Robe at Sanate Hill)

Abstract

There is a clear challenge to provide reliable cellular mobile service at remote locations where a reliable power supply is not available. So, the existing Mobile towers or Base Transceiver Station (BTSs) uses a conventional diesel generator with backup battery banks. This paper presents the solution to utilizing a hybrid of photovoltaic (PV) solar and wind power system with a backup battery bank to provide feasible and reliable electric power for a specific remote mobile base station located at Bale Robe. All the necessary modeling, simulation, and techno-economic evaluation are carried out using Hybrid Optimization Model for Electric Renewable (HOMER) software. The best optimal system configurations namely PV/Battery and PV/Wind/Battery hybrid systems are compared with the conventional stand-alone diesel generator (DG) system. Findings indicated that PV array and battery is the most economically viable option with the total net present cost (NPC) and per unit cost of electricity (COE). Simulation results show that the hybrid energy systems can minimize the power generation cost significantly and can decrease CO2 emissions as compared to the traditional diesel generator only. The sensitivity analysis has been carried out to analyze the effects of probable variation in solar radiation, wind speed, diesel price and average annual energy usage of the system load in the optimal system configurations. Ethiotelecom tower systems, especially those located in rough terrain, are currently powered by solar and diesel generator sets with battery backup. Diesel power generation is associated with several disadvantages which do not make it the best option. Generally, Ethiopia is blessed with Renewable Energy Resources (RES) which can be utilized at such towers to supply power. This study carried out measurements for wind speeds and solar insolation around Bale Robe, at Sanate site and compared these with data from secondary sources. A HPS system was designed based on the data collected. The design process basically involved selecting the best combination of HPS system components based on their cost and power characteristics. Finally, the study compared the designed power system and the current online system at the site in terms of cost of implementation and running.