Hamburg, November 14, 2025 – With an innovative flagship project, Sunnic Lighthouse GmbH (a subsidiary of ENERPARC AG), Entelios AG, and transmission system operator 50Hertz are setting new standards in the integration of renewable energies into system services: For the first time in Germany, a transmission system operator has prequalified a ground-mounted photovoltaic system for participation in ancillary frequency regulation services (aFRR) – both in a positive and negative direction. Since November 11, 2025, the ENERPARC PV plant in Schkölen (37.4 MWp) has been the first in Germany to be successfully marketed on the aFRR market. Other plants from Sunnic's portfolio are to follow as soon as they are prequalified. Particularly noteworthy is the close, cooperative partnership between the project participants, who recognized the potential of this new asset class at an early stage and jointly developed viable solutions for successful market integration.
Innovative strength through partnership
The project arose from a shared understanding of the growing importance of stabilization in the electricity system—especially against the backdrop of the increasing share of fluctuating renewables. In close cooperation, Sunnic, Entelios, and 50Hertz developed an innovative concept for integrating photovoltaics into ancillary frequency regulation services (aFRR). This results in two central application scenarios in aFRR marketing:
Negative aFRR (curtailment in the event of excess electricity):
During periods of high PV generation, such as in summer, the feed-in can be reduced at short notice. This relieves the grid and reduces the need to maintain fossil fuel power plants for the provision of control energy.
Positive aFRR (feed-in during shortfall):
In the event of an acute power deficit in the grid—even in times of negative electricity prices—a previously curtailed PV system can feed back into the grid within a very short time, thus contributing to grid stability. This rapid availability of renewable power makes PV systems a valuable component in the control energy market.
This flexibility shows how PV systems can contribute not only to decarbonization but also to system stability – a real added value for the entire electricity system.
Technological requirements at the highest level
Participation in secondary control power places high demands on forecasting systems, data quality, and technical processes. A comprehensive overall concept was developed for successful prequalification, addressing both the technical requirements and the regulatory requirements. A combined solution consisting of measurement technology, data management, and an AI-supported forecasting model was implemented on site. In close cooperation between Sunnic, Entelios, and 50Hertz, a robust system was created that forms the basis for successful participation in the aFRR market.
Breaking new ground with combined expertise
As one of Germany's most experienced flexibility service providers, Entelios contributes its comprehensive expertise to the development, simulation, and implementation of the prequalification and implementation concept. Sunnic complements this expertise with in-depth marketing expertise gained from more than a decade of working with PV generation profiles and, as part of the ENERPARC Group, direct access to one of Europe's largest operational solar park portfolios.
The project required intensive conceptual work, significant team resources, and close coordination with the transmission system operator—particularly with regard to regulatory requirements, technical interfaces, and the integration of forecasting systems. The result is a robust and transferable model that will enable other plants to access secondary control power in the future.
"The successful integration of our PV plant into the aFRR market is a paradigm shift – not only for Sunnic and our industry, but also for the entire energy system. Together with Entelios, we were able to implement a forward-looking concept that shows that even volatile renewable generation plants such as photovoltaics are capable of helping to stabilize our power grid in the event of fluctuations. The partnership-based and solution-oriented cooperation was a decisive factor in this success," emphasizes Arved von Harpe, Managing Director of Sunnic Lighthouse.
"We are proud to have been the first in Germany to prequalify a photovoltaic plant for the balancing power market together with Sunnic and 50Hertz. This project is a real milestone – and proof of what is possible when technological innovation meets partnership-based collaboration. For us at Entelios, it is a central goal to break new ground in flexibility marketing and to actively shape the energy transition together with strong partners," explains Fabian Becker, CEO of Entelios AG.
About Sunnic Lighthouse
Sunnic Lighthouse has been active in the German energy market since 2012 and offers tailor-made services from a single source – from direct marketing and electricity supply to trading. The subsidiary of ENERPARC AG specializes in the direct marketing of green electricity, which comes mainly from German photovoltaic and wind power plants. With a trading portfolio of over 4,800 MW of installed plant capacity, Sunnic Lighthouse is one of the largest direct marketers in Germany.
About Entelios AG
Founded in 2010, Entelios is a European pioneer in the field of industrial demand response services with extensive experience in flexibility optimization for complex plants in control reserve markets and intraday trading. Using proprietary systems, Entelios maximizes its customers' revenues by marketing flexibility on all relevant short-term markets and intelligently shifting capacity between FCR, aFRR, and intraday markets. Individual consulting and the identification of flexibility potential play a decisive role at Entelios. As a comprehensive service provider for control reserve markets, we support our customers at every step of the prequalification process and guarantee collateralization through our control reserve pools.
Press contact Sunnic Lighthouse:
Anke Dissel
Head of Marketing and Communications
Email: a.dissel@enerparc.com
Telefon: +49 40 75 66 449-471