This paper concerns the application of the first European example of a roof mounted, multi-operational ventilated photovoltaic and solar air collector, development of a detailed simulation methodology for such a system, and gives a brief outline of monitored findings after six months of operation. The aim for this simulation development was to provide a method that can aid future system design and optimize performance in line with energy requirements for specific buildings. This work is discussed in relation to two key investigations into the simulation of building integrated hybrid PV thermal collectors. (C) 2003 Elsevier Ltd. All rights reserved.