More Solar Power despite Congested Grids: Thüga Moves Medium-Voltage Series Regulator into Series Production

Munich — Rising rooftop solar installations are challenging distribution grid operators to make more efficient use of existing grid capacity. Thüga Aktiengesellschaft has therefore developed a compact medium-voltage series regulator (MSLR) together with TEN Thüringer Energienetze and Hitachi Energy, designed to enable more PV capacity without grid expansion.

In a pilot project in Hopfgarten near Weimar, the regulator has been installed in a distribution grid for the first time worldwide, according to Thüga. A sample calculation shows that this allows around 260 percent more PV capacity to be integrated — at the pilot site alone, this could enable around 2,750 additional balcony PV systems to connect to the grid.

How It Works: Voltage Control instead of Grid Expansion

The newly developed medium-voltage series regulator (MSLR) specifically corrects the voltage band in the medium-voltage grid, thereby increasing the capacity of existing lines to absorb PV feed-in rather than physically reinforcing the grid. The background to the bottleneck: in the grid area of TEN Thüringer Energienetze alone, 17 medium-voltage sections are currently "full" and can no longer accept additional PV feed-in — across the Thüga Group, all regional grid operators from the Baltic Sea to the Alps face the same challenge. The device is standardized based on Thüga specifications, is roughly the size of a large local grid transformer, and can be integrated into existing transformer stations without additional construction work. According to Thüga, pre-series tests have shown that the technology is robust against operator errors, and handling for grid technicians is expected to differ little from that of conventional components.

Cost Savings and Strategic Significance for the Thüga Group

Thüga Aktiengesellschaft defined the requirements for the MSLR based on findings from across the Thüga Group. TEN Thüringer Energienetze GmbH & Co. KG, based in Erfurt and a subsidiary of TEAG Thüringer Energie AG, operates the pilot grid in Hopfgarten. Hitachi Energy, with its German headquarters in Mannheim, will take over series production of the regulator at its transformer plant in Lodz, Poland. "Calculations for regional utilities within the Thüga Group show that by 2035, the use of MSLR could save individual grid operators a three-digit million-euro sum, if we deploy these regulators where it makes sense and is possible," said Dr. Constantin H. Alsheimer, Chief Executive Officer of Thüga Aktiengesellschaft. The MSLR is intended to help direct the billions of euros in planned investments that Thüga Group grid operators intend to make in their power grids over the coming years more effectively. According to Thüga, this can help limit the costs of grid expansion and, in turn, the rise in grid fees.

One Element among Several Grid Solutions

For Thüga, the MSLR is a complementary tool alongside other solutions such as controllable local grid transformers, storage systems or redispatch — particularly for applications requiring additional grid capacity at short notice. Following the launch of the pilot project, the technology is now also available to other distribution grid operators in Germany and Europe, with interested grid operators already able to order the regulator.

Source: IWR Online, 08 Jul 2026