Solothurn target grid planning

To efficiently meet the future requirements of the city of Solothurn’s power grid, the BFH Power Grids Laboratory is carrying out a target grid planning project with Regio Energie Solothurn for its medium and low-voltage grid.


  • Lead school(s) School of Engineering and Computer Science
  • Institute Institute for Energy and Mobility Research IEM
  • Research unit IEM / Power grids
  • Duration (planned) 01.08.2023 - 31.12.2024
  • Project management Prof. Michael Höckel
  • Head of project Stefan Schori
  • Project staff Sandro Bühlmann
  • Partner Regio Energie Solothurn
  • Keywords Target grid planning, electrification, sustainable energy supply, scenarios, grid model

Initial situation

The growth in electric mobility and increased use of heat pumps and photovoltaic systems may result in operational systems being overloaded and voltage limits exceeded on the distribution network, unless suitable measures are taken. A target grid planning project is being carried out for the medium and low-voltage levels in collaboration with BFH’s Power Grids Laboratory, to assess the impact on Regio Energie Solothurn’s power grid.


The first phase will evaluate the medium-voltage level, using the existing grid model in the NEPLAN grid simulation tool. The procedure includes a fundamental analysis of the situation in 2023, to assess the capacity utilisation and voltage of the sub-stations, medium-voltage lines and transformer stations. This is done by estimating performance values, factoring in various scenarios. Based on the 2023 scenario, the future development is estimated up to the years 2035 and 2050 for traditional consumption, electric mobility, heat pumps and photovoltaic systems per transformer station. The assessment of the future scenarios includes both the normal state and the state during disruption/switching, whereby various scenarios are defined and simulated.

Once the evaluation of the medium-voltage level has been completed, the entire low-voltage level will be analysed. The 2023, 2035 and 2050 scenarios will also be simulated on this grid level.


The results comprise a detailed analysis of the medium- and low-voltage levels, including capacity utilisation and voltage levels in 2023. The simulation results for 2023 will be compared with existing measurements to validate the accuracy of the simulations. The estimated development up to 2035 and 2050 will also be simulated for the various system types. This procedure is based on local forecasts of Regio Energie Solothurn as well as the Swiss Federal Office of Energy’s ‘Energy Perspectives 2050+’. The simulation results provide a reliable basis for the evaluation and planning of additional measures. They will enable bottlenecks in the distribution network to be detected quickly. The project results will allow Regio Energie Solothurn to make well-informed decisions on future grid investment.


The results of the grid simulation will serve as a basis for defining recommendations and measures. They will help to optimise and develop the power grid to meet the growing challenges presented by the increase in electrification and decentralisation. Future trends up to 2035 and 2050 will be taken into account to structure sustainable, efficient solutions for grid infrastructure. The insights gained will provide Regio Energie Solothurn with a reliable basis for future-oriented and resilient grid planning.