As part of EU Biosolarroofs concept, the project Photovoltaic Roofgardens combines previously separated disciplines as green roof construction, building-integrated photovoltaic systems and roof design. Producing renewable energy, offsetting increasing soil sealing, improving the micro-climate, storing CO2 and rain water and extending the life of the roof membrane – a combined roof system should do all this and much more. The aim of the project is to combine these concepts to develop one holistic system. Synergies will be found between areas that have until now competed with each other. For the development of such a holistic concept, the following comprehensive analysis was carried out: understanding of users and users’ needs, coordination of appropriate vegetation systems in combination with PV shading, effects of shading patterns on people, integration and coordination with the architecture, landscape planning, construction and irrigation concepts as well as cost and revenue. These concepts have been tested using demo simulations. The research project’s initial results were presented at BOKU Wien: the plant-filled roof terrace creates a pleasant, comfortable environment. The photovoltaic pergola with semi-transparent glass-glass modules provides shade and produces green energy. The wooden test facility at BOKU does not yet represent the final architectural design. But it is already clear how the solution works: the previously underutilised terrace has become an attractive recreational and meeting place with a noticeable three to five degree temperature difference. In the test garden, five tons of CO2 are saved every year thanks purely to the photovoltaic system, without taking account of the CO2 retention properties of the plants and soil. The plants also act as a fine dust filter. The final design of the photovoltaic roof garden consists of a green roof structure, a pergola made of wood or steel and a canopy with photovoltaic glass-glass modules. A photovoltaic roof garden unit measures around 56sqm and can be endlessly multiplied. It provides about 5.500 kilowatt hours of green energy a year, or enough to supply one to two households. The costs including plants, steel girder construction and photovoltaic system are around €79.500. At €1.400 per square metre, the photovoltaic roof garden costs roughly the same as a conservatory. But for the same price, it provides both green energy and pleasant, green surroundings.