The development of ground-mounted photovoltaic systems next to transport routes

Since 2009, Germany's Renewable Energy Sources Act has promoted the erection of ground-mounted photovoltaic (PV) plants next to transport routes (railways, federal roads and federal highways) as these areas are considered to be socially, economically and ecologically less valuable. Recent amendments to the act have gradually expanded this strip next to transport routes from 110 m in 2009, to 200 m in 2021 and 500 m in 2023.

Our study investigated the effect of these amendments by analysing the development of ground-mounted PV systems next to transport routes between 2000 and 2023 using geo-information data on plant sites, transport networks and site properties.

The area data for ground-mounted PV plants indicate that more and more PV plants are being built on land next to transport routes. Currently, 39 % of all ground-mounted PV plants (area) are located within 500 m of a transport route (6919.5 MW). Our analysis shows that the introduction of subsidies has stimulated the expansion of such installations along transport routes, however there has also been a general expansion of ground-mounted PV systems. Our research also reveals that this expansion did not start from zero, as it was already common practice that PV plants were being built on the 500-m strip many years before the subsidy was introduced. In terms of land use patterns and soil quality, the areas covered by PV plants next to transport routes are mostly agricultural areas with all levels of yield potential.