Europe’s largest solar power plant has been officially connected to the 50Hertz transmission grid south of Leipzig.
The Witznitz Energy Park, with an installed capacity of 650 MWp, boasts two remarkable features: it injects electricity directly at extra-high voltage and contributes to grid stability around the clock, even during nighttime.
Construction and Location
The Witznitz Energy Park was constructed over the past two years on a former lignite mining site spanning around 500 hectares within the municipalities of Neukieritzsch, Böhlen, and Rötha, near Hainer See.
A 380 kV overhead line runs along the site’s edge, connecting to the Lippendorf lignite-fired power plant via the Pulgar substation.
The solar plant is linked to this line through a new substation built by MOVE ON. The Energy Park was developed in multiple phases and has been supplying electricity to the grid since December 2023, but has only recently reached its full operational capacity.
Pioneering Grid Integration and Renewable Energy Contribution
Stefan Kapferer, CEO of 50Hertz, highlighted the project’s significance, stating, “In the early months of this year, renewables covered around 75% of electricity demand in eastern Germany and Hamburg.
The Witznitz Energy Park has already contributed to this, demonstrating that the expansion of solar power is reaching new heights.
50Hertz is a pioneer in integrating renewables into the power grid. By activating reactive power and incorporating the solar plant into our congestion management, we are once again leading the way in maximizing the utilization of electricity from renewable sources within the grid’s capacity.”
Reactive Power for Grid Stability
Reactive power, in addition to active power, is essential for the efficient delivery of electricity to consumers. It functions as a “lubricant” for transmission and is used to regulate specific grid sections based on regional supply and demand.
Fluctuations in reactive power can destabilize the standardized voltage. Traditionally, generators at large power plants have supplied reactive power while generating electricity, but it could also be requested by system management teams at transmission system operators (TSOs).
Pilot Project for Reactive Power Management
The Witznitz Energy Park will provide approximately 150 Mvar of reactive power, partially replacing the reactive power supplied by the neighboring Lippendorf lignite-fired power plant.
This power can be activated even when the solar plant’s inverters are not converting direct current into alternating current for grid injection.
Instead, the power electronics within the inverters will draw electricity from the transmission grid to generate reactive power. This capability makes the Witznitz Energy Park a crucial pilot project for 50Hertz, offering valuable lessons for future projects.
Regulatory Framework and Future Outlook
Starting in 2026, an EU Directive on the internal electricity market will mandate TSOs to procure reactive power through market-based tenders. Ruling Chamber 6 recently issued a final ruling on a procurement concept developed by the Federal Network Agency (BNetzA) for this purpose.