This paper deals with the prerequisites for a stand-alone fuel cell system installed to avoid replacing or upgrading an ageing, distant power grid connection which only supplies a few buildings with their power demands. The importance of sizing the included components in the energy system is presented in economic terms. The size of the fuel cell system and the energy storage system (battery, hot-water storage and hydrogen storage) are discussed in relation to the yearly distribution of the buildings' power demand. The main design idea is to decrease the size of the fuel cell system without making the battery too expensive and that the power requirements are fulfilled over test periods with decided length and power output. The fuel cell system installation is not economically viable for the presented conditions, but in the paper future feasible scenarios are presented. The calculated incomes are shown as a function of the size of the fuel cell system and energy storage, the electricity costs, the fuel costs including transportation, the prices of electricity and heat, and the fuel cell system costs and efficiencies. The main factor in the system's economic performance is the fuel price, which contributes more than half the costs for the fuel cell system-based energy system. The cost of the power grid is also determining for the result, where the distance to the main power grid is the important factor. The evaluation is performed from the utility company's point of view. (C) 2003 Elsevier Science B.V. All rights reserved.