„Neighbours are the tests that life sets us,“ as the French playwright Marcel Archand once said. Careful consideration must also be given when wind energy and photovoltaic systems are to be erected in the immediate vicinity. The advantages are obvious: paths, lines, transformer stations and grid connection points can be shared. This reduces costs and increases economic efficiency. The lower land consumption also ensures greater acceptance. 

In terms of planning law, however, it is not so simple, as wind turbines and photovoltaics are subject to different legal requirements. In accordance with Section 35 (1) No. 5 of the German Building Code (BauGB), wind turbines are privileged in outdoor areas. This only applies to photovoltaic systems to a very limited extent in a 200-metre strip along motorways and railway lines of the superordinate network (Section 35 (1) No. 8 BauGB). As a rule, the authorisation of a photovoltaic system in an outdoor area therefore requires a development plan.

The planning of wind turbines is also controlled by regional planning. In future, wind turbines will only be privileged if they are located in so-called „wind energy areas“. By selecting these areas, the federal states fulfil their obligation under the Wind Energy Area Requirements Act, according to which they must designate a percentage of their land area for onshore wind energy. These are areas in which other spatially significant functions or uses are excluded in accordance with Section 7 (3) No. 1 of the Spatial Planning Act (ROG), insofar as these cannot be reconciled with the prioritised use of wind energy. In order to ensure that this priority is also given to local authority planning sovereignty, Section 1 (4) BauGB also stipulates that local authority land-use plans must be adapted to the objectives of spatial planning.

As far as can be seen, case law has not yet decided whether photovoltaics is compatible with the prioritised use of wind energy. In practice, there are isolated voices that consider photovoltaic systems to be inadmissible in priority areas for wind energy. For example, the state government of Mecklenburg-Western Pomerania has taken a corresponding stance in its notes on the spatial planning assessment and building law judgement for large-scale photovoltaic systems in outdoor areas. However, such a blanket exclusion is unlikely to be justified. This is because the technically required distances between wind turbines also leave room for other uses. The decisive factor is that priority is ensured on a permanent basis. What needs to be taken into account depends on the circumstances of the individual case.