Comparative Study on Storage Devices for Standalone Hybrid Energy Systems

Background/Objectives: The intermittency in the renewable sources is a great menace to the quality of the power delivered and to the lifetime of the components. In the process of straightening up the short coming storage devices come in handy. Methods/Statistical Analysis: Batteries and fuel cells are the commonly used storage devices for Photovoltaic system. Recently ultra-capacitors are introduced in combination with storage devices as it has a better power density as compared to batteries and fuel cells. Also, the ultra-capacitors can provide higher energy for a short period of time. This paper deals with comparison of different storage devices incorporated with the Photovoltaic panels. A combination of PV/battery, PV/fuel cell and PV/battery/ultra-capacitor are taken into consideration. Findings: The number of PV panels in parallel, number of batteries in parallel and the number of fuel cells are the variables that are considered for the minimization of cost and Expected Energy Not Served (EENS) using the Non-dominated Sorting Genetic Algorithm II (NSGA-II) in MATLAB programming environment. The load profile and the solar irradiation data of Zaragoza (Spain) are considered for implementation. It is finally concluded that PV/battery/ultra-capacitor combination gives minimum cost and EENS as compared to the PV/battery and PV/fuel cell based systems. Applications: This can be applied as an optimization tool to bring out the conclusion in choosing an appropriate storage device, in combination with the renewable PV based standalone system.