About three quarters of the photovoltaic capacity installed in Germany is roofing systems and a quarter is open space systems. The area required for one megawatt of open-space photovoltaic systems is steadily decreasing. In 2006, 4.1 ha / megawatt was required, in 2019 – only 1.2 ha / megawatt. This is due, among other things, to the constant increase in the performance of the modules. As a result, significantly more solar energy can be harvested in this area today. Compared, in particular, with bioenergy, the output of electricity from photovoltaic plants, depending on the area, is many times higher.
At the end of 2019, open-air photovoltaic systems in Germany covered a total of 30,000 hectares, of which almost 26 percent was arable land and 14 percent bordering transport routes, some of which could also be arable land. The installed photovoltaic capacity in these two land categories is 0.07 percent of the total agricultural land in Germany. According to EEG 2017, photovoltaic systems are only suitable for confined spaces. On arable land (only in deprived areas), photovoltaics is currently subsidized in only five federal states, in each case in limited quantities. Criteria are being developed as part of a research project commissioned by the Federal Environment Agency. in order to further align the background with environmental concerns and at the same time ensure continuous expansion. However, it is fundamentally desirable to continue installing as much of the required rooftop PV systems as possible in order to reduce the need for additional space.