Modelling and optimization of micro grids for rural areas in Lesotho

Abstract

The study analysed different types of hybrid micro grids system configurations and found out the following to be both technically and economically viable: (a) PV with Levelised Cost of Electricity (LCOE) of R4.64/kWh, (b) PV/Wind of R5.03/kWh, (c) PV/Wind/Generator at R5.16 /kWh and lastly (d) PV/Generator of R4.80/kWh. These viable system configurations have more than 93.1 % renewables. All four technically and economically viable system configurations were found to be more sensitive to either price of diesel or inflation rate. As diesel price increased from R13.00/litre to R15.00/litre, LCOE increased from R5.15/kWh to R5.24/kWh. As inflation rate changed from 5.00 % to 6.50%, LCOE decreased from R4.64/kWh to R4.42/kWh. The most suitable system configuration has been found to both technically and economically viable is solar/generator with LCOE of R4.80/kWh and lower carbon emissions of 4843 kg/yr greenhouse gas emissions. For this solar/generator, NPV is R940 994.00, IRR is 18%, while ROI is 15.5% and payback period is 5.81 years. Any hybrid micro grid system that had hydro component in its system configuration was found to be not viable due to the high capital cost which contributed to high LCOE. The high cost of the system configuration that included the hydro component had been brought about by the high cost of civil works for erecting diversion weir for the micro grid power station.