Photovoltaic systems contain about two billions of solar modules worldwide. In order to monitor proper function of these photovoltaic systems, efficient and fast diagnostic methods are needed. Our workgroup "Sensor Technology" investigates such methods, in particular based upon daylight luminescence, in the research project PARK. PARK receives funding by the German federal ministry BMWi. Our project partner Solarzentrum Stuttgart GmbH is worldwide sucessfully using daylight luminescence, which was originally developed at ipv. The EU COST Action PEARL PV enables exchange on related topics with many workgroups all over Europe. Our cooperation with Biametrics GmbH evaluates innovative diagnostic methods for bioanalytics, funded by a technology transfer fund of the University of Stuttgart.