Because poly-crystalline silicon PV-cells are cheaper than mono-crystalline silicon PV-cells and still has a high efficiency these are used for the proto-types of the PV-windows. Silicon wafers are usually not transparent. Therefore the project group has worked with variations in the design of the PV-pane, e. g. the size of the silicon wafers and carving of patterns within the PV-cells, which helps to transmit more daylight through the facade, cf. figure 1. The shaping of the design adds a degree of freedom for architects to work with daylight in building design. But this degree of freedom will raise the price, reduce the total area of the PV-cells in the window and hence reduce the electricity output of the PV-window. Therefore this has to be made as an additional choice to the standard PV-pane. The design of the PV-window must reflect the desire for daylight distribution and the electricity production. Figure 1 illustrates some of the degrees of freedom in placement and carving of the PV-cells in the pane.