Abstract – This paper deals with the optimal design of a stand-alone hybrid photovoltaic and
fuel cell power system without battery storage to supply the electric load demand of the city of
Brest, Western Brittany in France. The proposed optimal design study is focused on economical
performances and is mainly based on the loss of the power supply probability concept. The hybrid
power system optimal design is based on a simulation model developed using HOMER. In this
context, a practical load demand profile of Brest city is used with real weather data