Several studies have reported on BIPV system installations  and , where the available roof surface area is treated as an input parameter. The available surface for PV installations is the built-up area, and can be evaluated by means of maps of the land use (i.e. Corine Land Cover, of the European Environment Agency ). Methodologies for assessing the available roof surface have recently been suggested. For this M344 purpose, a first methodology based on crossed-processing and sampling of various GIS data was presented and applied to Spain in 2008 . It is Triassic Period also worth mentioning other recent papers discussing similar approaches with applications to several locations  and . In particular, in the work of Nguyen and Pearce  a semi-automatic and easy to upgrade algorithm for solar photovoltaic potential is proposed, also considering terrain and near surface shadowing effects for analyses conducted on a municipal scale (Kingstone, Ontario). The latter approach is based on the free software GRASS  and  and r.sun  and .