Due to the increasingly dominant climate change, ?green? energy sources that do not contribute to further damage of the environment play an emerging and relevant role. A big advantage is that this kind of energy can be generated not only on a large scale, such as by wind turbines or hydroelectric power plants, but also by individual households through (among others) so-called Photovoltaic-Battery (PVB) systems which are based on solar energy. Compared with energy from the power grid, such systems naturally involve higher acquisition costs, which can, however, potentially be amortized. This raises the question of how large such systems should be designed, what the optimal strategy of usage is, and how relevant typical sizes of the individual elements available on the market are to the design strategy. Against this background, we investigate the problems addressed, taking into account different pricing strategies, and show, based on a simulation study, that PVB systems can bring major benefits in the long term. Additionally, our results indicate, that ? to a certain extent ? efficient energy management is able to compensate for limitations in sizing.