Performance of Integrated Photovoltaic Roofs

The application of Photovoltaic (PV) systems has been supported strongly by the Dutch Government during the recent years. Several big projects have been heavily subsidised. At first instance this seems surprising, because the costs for PV -systems are very high, specifically in The Netherlands, with low energy prices and a very efficient energy distribution network. The policy however, is based on the opinion that large-scale introduction of network coupled PV -systems is the best solution to the future shortage in fossil fuels. An important advantage of PV -systems is that they do not have any moving parts and therefore are practically maintenance free and also do not produce any noise. Specifically when they are integrated in the building envelope (as building materials) they do not require any extra space such as windmills. Two major projects that recently have been realised are Nieuw-Sloten near Amsterdam and Nieuwland at Amersfoort with 250 kWp and 1,3 MWp installed capacity respectively. The paper describes the procedures that have been developed to evaluate integrated PV -roofs. These procedures are mainly based on prototype testing and need to be scientifically validated. Knowledge gaps are observed, specifically with respect to building physical aspects such as the possible need for ventilation, ther mal performance, pressure equalisation and driving rain effects.