Techno-economic optimum sizing of hybrid renewable energy system

Using off grid hybrid renewable energy systems for rural electrification has become an attractive solution for those areas, where grid electricity is not feasible or cost of the grid extension is relatively large. Hybrid system combines several energy systems together, therefore it can supply high reliable electricity rather than a PV/battery system or a wind/battery system. But the most important thing is that the system should be economically attractive. To achieve both of these features, each of the components in the hybrid system should be optimally sized. This requires a detailed techno-economic analysis of different possible hybrid system configurations. The objective of this study is to investigate an optimum combination of different energy systems which can supply electricity to a rural community in Sri Lanka at an affordable price with an accepted level of reliability. The analysis of the hybrid system is done using the micro grid optimization software “HOMER”. A PV/wind/battery/ generator hybrid system is selected because the selected area receives abundant of sunlight and wind power throughout the year with an annual average solar radiation of 5.32 kWh/m²/day and an annual average wind speed of 6.27 ms^-1. The system with capacities, 20 kW-PV, 40 kW-wind, 20 kW-generator and a battery bank with 40 batteries is chosen as the optimal hybrid system configuration based on the HOMER optimization and sensitivity results. It can supply the electricity with a levelized cost of 0.36 $/kWh, which is substantially higher than the price of the grid electricity in Sri Lanka. But due to the unavailability of the national grid, this type of system is required to supply the electricity for rural communities to improve the rural lifestyle and at the mean time these systems will help to reduce the greenhouse gas emissions as well.