Technical and economic design of an off-grid photovoltaic-battery-diesel generator system

Energy supply in the remote areas is generally performed by off-grid fossil fuel based generators. The integration of a photovoltaic (PV) plant and a battery energy storage (BES) system is an effective solution to increase reliability, system autonomy and lifetime, to reduce the generator working hours, to improve the generator management and to reduce the system environmental impact. A PV-BES-Diesel generator system may introduce technical, economical and environmental benefits compared to traditional off-grid systems. This paper presents a technical and economic model for the design and management of an off-grid PV-BES-Diesel generator energy production system. The aim is to determine the PV system rated power, the BES system capacity and the technical configuration able to minimize the Levelized Cost of the Electricity (LCOE). The comparison between LCOE values of a PV-BES-Diesel generator system and a single diesel generator system allows to determine the economic advantages of the studied energy production system. The proposed model is applied to the design of a PV-BES-Diesel generator system to be installed in a remote village in Yakutsk (Russia). The model takes into account the hourly energy demand, the irradiation and temperature profiles of the installation location calculating the hourly PV plant yield, the battery charge-discharge processes and the required generator energy. The results highlight the technical feasibility and the economic profitability of the system for a context with a medium irradiation level, i.e. ~1400kWh/m2year, and relatively low fuel cost, i.e. 0.7€/l. Considering the best PV rated power and the BES capacity configuration, a reduction of 8.5% of the electricity unitary cost respect to the single diesel generator system is obtained.