PV system participates in the balancing energy market for the first time

14.11.2025

Source: E & M powernews

A 37.4 MW PV system is the first system in Germany to pre-qualify for the supply of secondary balancing power.

Enerparc's PV plant in Schkölen (Thuringia) with a capacity of 37.4 MW has been participating in the balancing energy market since November 11. For the first time in Germany, a transmission system operator has prequalified a ground-mounted photovoltaic system "for participation in secondary balancing power - both in the positive and negative direction", according to a press release from Sunnic Lighthouse.

The grid frequency in the electricity grid must be stable at 50 Hertz. If deviations occur, various reserve power measures take effect in stages. The secondary control power - also known as "aFRR - automatic Frequency Restoration Reserve" - is activated after around 30 seconds and the participant must provide the full agreed power within five minutes. The system operator proves that it meets the technical, operational and organizational requirements for this via prequalification.

The service providers Sunnic Lighthouse, Entelios and the transmission system operator 50 Hertz have developed a joint concept to technically and organizationally integrate photovoltaic systems into the secondary control reserve. The special feature of the solar park is that the system can not only be curtailed, but also provides additional feed-in when there is a shortage of electricity.

"Precise forecasts, high-quality data"

There are two application scenarios for marketing. In the case of negative secondary control power, the output of the system is reduced if there is an oversupply of electricity in the grid. This occurs in particular during periods of high solar production.

If positive secondary control power is required, i.e. when there is a shortage of electricity in the grid, the system feeds power back into the grid at short notice after it has previously been curtailed. In this way, photovoltaics can contribute to the stability of the power supply.

Participation in the secondary control reserve requires precise forecasts, high-quality data and robust technical processes. An overall concept was necessary for the prequalification, "particularly with regard to regulatory requirements, technical interfaces and the integration of the forecasting systems", it continues. This required close coordination with the transmission system operator.

"Paradigm shift" for the industry

Further systems from Sunnic's portfolio are to be integrated into the balancing energy market as soon as they are prequalified. "The successful integration of our PV system into the aFRR market is a paradigm shift - not only for Sunnic and our industry, but also for the entire energy system," says Arved von Harpe, Managing Director of Sunnic Lighthouse.

Sunnic Lighthouse offers services ranging from direct marketing to electricity supply and trading. The Enerparc subsidiary specializes primarily in the marketing of electricity from renewable energies. Entelios is active in the field of industrial demand response solutions and has experience in flexibility optimization for complex plants in control reserve markets and intraday trading.

Author: Stefan Sagmeister