The electricity benefits of daylighting and photovoltaics (PV) in various solar facade layouts in buildings at four locations have been analysed. The optimal division between the window area and the PV area has been determined. A bigger window will reduce the electric lighting requirement, but it will decrease the available facade area for PV electricity production. The window area in the facade layouts studied in this paper ranges from 14 to 60% of the total facade area, with the rest of the southern facade area covered by PV panels. No PV is installed on the northern facade. With a minimum window area, and continuous electric light dimming acid shading of the window, 58% of the annual lighting requirement of the building during the office hours can be provided by daylight in Southern Europe (38 degreesN) and 44% in Northern Europe (60 degreesN). The daylight availability can be increased to 78% in Southern and to 61% in Northern Europe by increasing the window area from the minimum 14 to 24% of the total facade area. A further 10% increase in the daylight availability can be achieved by enlarging the window area to 38%. Considering both the electric lighting requirement replaced by daylight and the electricity produced by the PV panels, the maximum electricity benefit with high-efficiency PV is achieved at all four locations: with a facade layout with a window area of 24% of the total facade area. (C) 2001 Elsevier Science B.V. All rights reserved.