This paper focuses on a study of an hybrid energy storage system constituted by lead acid batteries and supercapacitors and designed to work in a low voltage DC microgrid supplying by photovoltaic sources and dedicated to building application. We proposed a simulation methodology in order to evaluate supercapacitors performances and behaviors for long term analysis. We quantity their impacts on battery lifetime and on the levelized cost of electricity of our storage system. This analysis has been validated on the micro-grid developed in LAASCNRS in ADREAM building integrated photovoltaic. The power profiles used for our work correspond to 1 years production and consumption data from 100m 2 floor of the building. Results of comparative studies with different load profiles, SC costs and methods to estimated battery lifetime are presented and discussed.