Germany has served as a role model in photovoltaic technology diffusion amongst house owners in the last two decades. A strong feed-in tariff scheme based on the Renewable Energies Act (EEG) supported and to some extent - enabled this development, but due to skyrocketing costs it already has been and will be further reduced. So far changes in public policy have only slightly affected house owners with photovoltaic panels on their own house, but future policies have not been decided yet. This article uses the methodology of System Dynamics to develop a model of the German photovoltaic market for small plants on private houses and tests public policies. Amongst them are different scenarios regarding the reduction or even removal of the feed-in tariff scheme in Germany. The results can improve German public policies in the field of photovoltaic technology diffusion and serve as an example for other countries and other renewable energy diffusion cases. (C) 2018 Elsevier Ltd. All rights reserved.