Welcome to the official website of IEA SHC Task 35 "PV/Thermal Solar Systems" - a three year research work task initiated January 1, 2005, as part of the International Energy Agency (IEA) Solar Heating and Cooling (SHC) Programme. This site contains a description and overview of the Task and the results from the work. The objectives of this Task are to catalyse the development and market introduction of high quality and commercial competitive PV/Thermal Solar Systems and to increase general understanding and contribute to internationally accepted standards on performance, testing, monitoring and commercial characteristics of PV/Thermal Solar Systems in the building sector. The heart in a PV/Thermal Solar System is a PhotoVoltaic/Thermal module, or PV/T module which is a combination of photovoltaic cells with a solar thermal collector, forming one device that converts solar radiation into electricity and heat simultaneously. Apart from the PV/T module also components as hot water storage tanks, heat exchangers, piping, controllers, inverters, wiring and heat pumps can form part of a PV/Thermal Solar System. PV/T modules can generate more energy per unit surface area than side by side photovoltaic panels and solar thermal collectors, at a potentially lower production and installation cost. Moreover, PV/T modules share the aesthetic advantage of PV. Because of their high efficiency per unit surface area, PV/T is particularly well suited for applications with both heat and power demand and with limited roof space available. Therefore, the potential of PV/T is especially large in the residential market, both collective and individual. An overview of commercially available PV/T products can be downloaded here. There are many ways to combine the different PV and Solar Thermal technologies to a PV/T collector: crystalline or amorphous silicon or thin-film PV, liquid or air collectors, flat-plate or concentrating technologies with or without transparent cover, some fully building integrated. So far, most development has been done on silicon technologies with liquid and air, flat-plate type collectors. Furthermore, work has been done on concentrating and combined liquid/air PV/T collectors and on building integrated systems for preheating of e.g. ventilation air.