From pv magazine Germany

Germany's Fraunhofer ISE has identified significant potential for PV deployment along Germany’s railway network. It found that areas within 2 km of a substation could host up to 37.6 GW of solar capacity.

The institute said inverters enabling direct feed-in to the railway grid will be key to overcoming regulatory and market barriers that have so far limited such installations. The findings stem from the “PV4Rail” research project, funded by the Federal Ministry for Economic Affairs and Energy, which seeks to integrate PV directly into the country’s 16.7-hertz single-phase railway grid.

“A significant portion of the energy demand in the railway power grid could, however, be covered by solar PV, because the potential for photovoltaic areas along railway lines is many times higher than the amount of energy required in the railway power grid,” said Andreas Hensel, PV4Rail project manager at Fraunhofer ISE.

Fraunhofer ISE estimated an annual generation potential of 32,920 GWh from solar systems near railway substations, compared with about 7,500 GWh of electricity demand for train operations in 2023. The potential could be even higher considering the nearly 8,000 km of power grid operated by national rail operator Deutsche Bahn.

While Germany has trialed several pilot projects, they have been constrained by grid compatibility and inverter technology. Vensys Elektrotechnik GmbH, a partner in the project, has developed a 2 MW central inverter divided into two 1 MW sections. One of the units, tested at Fraunhofer ISE’s laboratory, achieved 96.6% efficiency.

Fraunhofer ISE has also developed control systems for grid-forming inverter operation, analyzing connection options based on system size. PV systems up to 5 MW could feed directly into overhead lines, while systems up to 12 MW would need to connect via busbars at substations. Larger systems, up to 40 MW, would require dedicated substations with transformers and switchgear to integrate into the 110 kV railway network.

Austria has already demonstrated large-scale solar integration into its railway grid, with multiple systems above 10 MW feeding power directly into the network. Fraunhofer noted, however, that grid-connection standards differ between Austria’s ÖBB and Deutsche Bahn.

Due to the technical and safety requirements of Germany’s railway grid, only voltage-impressing inverters can currently be used. Fraunhofer said this behavior has been validated in simulations under the PV4Rail project and could advance to real-world implementation in a follow-up phase.

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