In this study the actual costs of electricity produced by PV generators placed on buildings have been examined for UK and Greece. The type of buildings that were considered include medium size houses for up to four people, and buildings for offices/small business and hotels (Greece only). The chosen case studies were considered to be for new or refurbishment buildings, and, in the case of not integrated systems, for existing buildings that have the capacity to incorporate a PV installation on their present structure. The analysis has been done with the aid of PVSYST software. The costs have been derived for a working PV period of 25 years. Apart from that, a forecasting, through sensitivity analysis, of the likely relation between the price of the PV generated electricity and the price of electricity-buying power from the grid has been evaluated, examined, and analysed for the next decade. The main aim was to estimate when the prices of the PV generated electricity would be attractive to the potential costumers. The sensitivity analysis has been focused on different potential scenarios. The results identify that the period in which the profitable installation of a PV system on buildings will be a reality is estimated to be 2007-2011. During this period, BiPV installations on UK will become profitable before those in Greece. (C) 2003 Elsevier Ltd. All rights reserved.