The construction of solar power plants has until now followed the principle that individual plants should produce as many kilowatt-hours as possible. The reason for this is the Renewable Energy Act, which treats every kilowatt-hour of solar power produced equally, regardless of the date the plant was built. The result of this regulation is that solar plants are mainly concentrated southern Germany, and are mainly south-facing.
In the future, it will not only be important to produce one kilowatt-hour of power as cheaply as possible, but also that they will be integrated as cheaply as possible into the system. Further expansion of photovoltaic arrays in areas of Bavaria, where just under 40 percent of photovoltaic potential has already been exhausted, could bring with it the high cost of expanding distribution networks. That contrasts with Berlin, where only 1.5 percent of photovoltaic potential is used. In addition, the sun does not shine evenly over Germany, so that distributing new facilities widely would create a more balanced production of solar power. In addition, building east- and west-facing solar arrays would bring considerable advantages.
Agora Energiewende asked the Fraunhofer Institute for Solar Energy Systems (ISE) to look more closely at the effects, in order to better understand the trade-off between higher specific power production costs on the one hand, and lower total system costs on the other hand. The knowledge gained from this study can be used in developing tendering models for photovoltaic subsidies, and can also offer ideas for revising the previously state-set feed-in tariffs per kilowatt-hour of power.