Multiple use of areas on land easier than at sea

08.05.2025

Source: E & M powernews

Where space and grid connections are scarce, it could help to combine wind and solar power. Two studies investigate the possibilities for such combinations at sea and on land.

As part of the Berlin Energy Days online, two studies were presented that examine the potential of joint land use for various renewable energy generators. The background to this is the ambitious German expansion targets for renewable energies and the limited space available. In particular, the combination of wind energy and photovoltaic systems appears to make sense, as they often generate electricity at different times and can complement each other.

Hybrid projects offer two main potentials: on the one hand, land requirements can be reduced through the joint use of land and, on the other hand, synergies in the area of grid connections and infrastructure can be leveraged. Corresponding analyses can be found in two research projects commissioned by the Federal Environment Agency on projects with offshore wind turbines and floating PV systems and on projects with onshore wind turbines and ground-mounted PV systems.

Offshore combinations not yet implemented

The areas of an offshore wind farm could, for example, be supplemented by floating PV systems in the future. Such combinations have not yet been implemented commercially; initial trials have only been carried out in China and the Netherlands. The obstruction of shipping traffic and the severe corrosion of the PV modules caused by salt water appear to be problematic here. The integration of tidal, wave or floating wind power would also be possible.

From a legal perspective, multiple use has not yet been explicitly anchored in spatial planning law. Nevertheless, existing planning instruments - in particular the spatial development plan for the Exclusive Economic Zone (EEZ) and the land development plan - already permit such utilization concepts, said Franziska Stamme, one of the study authors. "Hybrid energy generation can be a key to making better use of limited areas in the EEZ. However, the approval regime under the Wind Sea Act would have to be specifically adapted for this," she concluded.

More hybrid land use on land

On land, on the other hand, wind farms are already sometimes combined with ground-mounted PV systems. The recently approved joint use of the grid connection could make this more attractive in the future. The project planners interviewed for the study are particularly interested in the more efficient use of previously contaminated land, especially as contacts already exist with landowners and authorities. Access routes, cable routes and grid connections can also be used.

According to the survey results, however, different approval authorities and procedures for wind (BImSchG) and PV (building regulations of the respective federal states) and the frequent lack of exchange between the authorities are an obstacle. The study therefore suggests that there should be uniform criteria for approvals that apply nationwide and are not designed differently in each municipality and for each grid operator.

The study for offshore turbines was carried out by the Institute for Climate Protection, Energy and Mobility (Ikem) together with Deutsche Windguard GmbH, Bio Consult and Helmut Schmidt University Hamburg. For the combination on land, the study was carried out by Deutsche Windguard, the Environmental Energy Law Foundation and the law firm Engemann und Partner.

The Ikem study on the multiple use of offshore areas is available on the Internet.

The study on the utilization of wind power and PV on land by the German Windguard is available for download as a PDF.

Author: Susanne Harmsen