International Journal of Science and Research (IJSR) ISSN: 2319-7064 Impact Factor (2018): 7.426 Volume 8 Issue 1, January 2019 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Optimal Sizing of Grid Connected PV/Wind Hybrid System Using Homer Software Abiy Mekonnen Addis Abeba Science and Technology University, Ethiopia Abstract: The renewable energy sources have increased significantly due to environmental issues and fossil fuels elevated cost. Integration of renewable energy sources to utility grid depends on the scale of power generation. Large scale power generations are connected to transmission systems whereas small scale distributed power generation are connected to distribution systems. Conventionally a battery bank is used as the backup system in standalone Hybrid Renewable Energy Systems (HRES) while in grid- connected systems the grid performs as the backup during power shortage periods. For the latter, different prices of electricity during peak and off-peak hours raises a question about the cost effectiveness of using the grid as a backup this paper focuses on the design of an optimized grid connected small-scale HRES, The performance of the proposed design method is evaluated based on a case study for a typical Village in Ethiopia. Keywords: Wind energy, solar energy grid-connected hybrid systems 1. Introduction Ethiopia has a lot of small hydropower, solar and wind energy potentials convenient for rural electrification. It is conceivable that a hybrid system has the advantage of improved reliability and therefore gives better energy service when compared to any particular (wind, solar, etc.) type of stand-alone supply system. What this means is that in the absence of one type of energy (example: solar energy during nighttime) another could be available (example: wind) to carry out the service. Hence, hybrid systems are found to be more appropriate than single stand-alone resources. Conventionally the balance between demand and HRES is obtained by grid in grid-connected systems and overproduction is sent into the grid. In these systems, the grid performs as the storage system with infinite capacity which makes the HRES reliable at any time. However different grid electricity prices in peak and off-peak hours could become an economical challenge in maintaining power shortage in peak hours from the grid. The generated power by wind turbine and PV arrays are depended on many parameters that the most effectual of them are wind speed, the height of WTs hub (that affects the wind speed), solar radiations and orientation of PV panels. In certain region, the optimization variables are considered as the number of WTs, number of PV arrays, and installation angle of PV arrays, number of storage batteries, height of the hub and sizes of DC/AC converter. goal of this work is optimal design of hybrid system for the one village in southern part of Ethiopia. The data of hourly wind speed, hourly vertical and horizontal solar radiation and load during a year are taken from some secondary data centers. 1.1 Current status of energy Development in Ethiopia Table 1: Indigenous energy resources in Ethiopia (Report on Ethiopian Energy Sector [1]) Resource Unit Exploitable reserve Exploitable percent Hydro power MW 45000 <5% Solar /day KW/m 2 Av 5.5 <1% Wind power : Speed GW m/s 1350 > 6.5m/s <1% Geothermal MW 7000 <1% Wood Million tones 1120 50% Agriculture Waste Million tones 15-20 30% Natural gas Billion m 3 113 0% Coal Million tones 300 0% Oil share Million tones 253 0% Renewable energy resources like solar and wind offer clean and economically competitive alternatives to conventional power generation where high wind speed and high solar radiation are available. For meeting the energy demand, PV wind hybrid power generating systems can be beneficial in enhancing the economic and environmental sustainability of renewable energy systems. Hybrid power systems are designed for the generation of electrical power using number of power generation devices such as wind turbine, PV, micro hydro and/or other conventional generators. In addition, it includes power electronics and electricity storage bank. Some of the advantages of using RESs are gain an immediate access to reliable electricity at any time; reduce the dependency from oil price fluctuations and the transportation costs of fuels; increase economic productivity and fight climate change. 1.2 Importance of the Hybrid System Hybrid power supply systems consist of different energy sources in order to have more secured supply of electrical loads with increased reliability and durability of the system. The hybrid systems take advantage of the strengths of the subsystems to overcome the weaknesses of the individual systems. The features of the hybrid systems are mainly more reliable and less expensive than the conventional systems, because the solar sources are available during the day while the wind energy is 24 hours a day. It should be noted that wind and solar energy sources are practically free after the installation of their infrastructure. An efficient management or control system can determine the power flow to the loads from various components of the hybrid system during the period of operation. Note that in a hybrid system, the individual power sources are operating like a team supporting each other in a highly reliable manner. It is obvious that when the energy is drawn from the solar Paper ID: ART20194114 10.21275/ART20194114 482