Technical and economic design of photovoltaic and battery energy storage system

Abstract In the last years, the technological development and the increasing market competitiveness of renewable energy systems, like solar and wind energy power plants, create favorable conditions to the switch of the electricity generation from large centralized facilities to small decentralized energy systems. The distributed electricity generation is a suitable option for a sustainable development thanks to the environmental impact reduction, the load management benefits and the opportunity to provide electricity to remote areas. Despite the current cut off of the national supporting policies to the renewables, the photovoltaic (PV) systems still find profitable conditions for the grid connected users when the produced energy is self-consumed. Due to the intermittent and random nature of the solar source, PV plants require the adoption of an energy storage system to compensate fluctuations and to meet the energy demand during the night hours. This paper presents a technical and economic model for the design of a grid connected PV plant with battery energy storage (BES) system, in which the electricity demand is satisfied through the PV–BES system and the national grid, as the backup source. The aim is to present the PV–BES system design and management strategy and to discuss the analytical model to determine the PV system rated power and the BES system capacity able to minimize the Levelized Cost of the Electricity (LCOE). The proposed model considers the hourly energy demand profile for a reference year relating the analysis to the hourly irradiation and the temperature trend for the installation site. Furthermore, the proposed model is applied to design the grid connected PV–BES system installed at the new buildings of the Engineering and Architecture School of the Bologna University, Italy. A multi-scenario analysis is assessed varying the PV–BES system rated power and capacity. The results highlight the technical feasibility and the economic profitability of such a system for the proposed context. A reduction of 25.5% of the electricity cost respect to the grid electricity price benchmark is among the key outcomes discussed in the present paper.