Photovoltaics on buildings is always tailor-made and can be integrated into a new building or added to an existing building. The PV modules and their mounting structure fulfil important functions of the building envelope in the building-integrated sector, in contrast to rooftop systems. Photovoltaic systems on old buildings are also possible. Preserving the architectural image is very important here and places demands on design, monument templates and integration into the surroundings.