Probabilistic reliability evaluation of off-grid small hybrid solar PV-wind power system for the rural electrification in Nepal

Nepal is a small mountainous developing country where awareness about electricity from renewable energy resources is increasing with the rapid depletion of fossil fuel resources, sustained higher oil prices and environmental concerns. Among the various renewable energy resources, off-grid small hybrid solar PV and wind power system (HSWPS) seems to be the promising solution to provide reliable power supply with improved system efficiency at reasonable cost for the remote rural areas in Nepal. This paper is focused on the study and analysis of hybrid system reliability for the electricity supply for off-grid applications with focus on solar photovoltaic-wind hybrid system based on current load profile of a real system. Various reliability indices like Loss of Load Expectation (LOLE), Expected Energy Not Served (EENS), Energy Index of Reliability (EIR), Expected Customer Interruption Cost (ECOST) are evaluated through Probabilistic Approach using Analytical Method. The paper assesses the reliability of hybrid generation system of a recently completed HSWPS at a remote location in Nepal. The wind turbine generator (WTG) is the primary source of supply to the system; while the solar PV array is the secondary source of supply with the battery included as backup system. It is expected that the findings for this project would be useful for similar hybrid system reliability studies in the future.