Digital controllability check: SISSY consortium demonstrates a new approach to verifying controllability

With its SISSY Consortium’s digital controllability check, based on intelligent metering systems (iMSys), the consortium is demonstrating a new, scalable method for verifying the controllability of generation plants. This approach makes it possible to verify basic controllability efficiently, in a manner that benefits the grid, and without the need for physical intervention or test-based curtailment of renewable generation capacity. This establishes a procedure that is particularly suitable for large fleets of plants and meets the increasing demands of the energy transition.

Regulatory background and challenge regarding the controllability check

The background to this is the amendment to the Energy Industry Act (EnWG). This took place in February 2025. Section 12(2b) introduced the so-called ‘controllability check’. This requires proof that plants can be reliably controlled when necessary. Under current guidelines from transmission system operators, the controllability check is currently mostly carried out purely physically via metrological verification through active power reduction.

In practice, however, this approach presents significant challenges – particularly in view of the growing number of decentralised generators such as photovoltaic systems, battery storage, heat pumps and charging facilities. This is precisely where the digital controllability check comes in, offering a significantly more efficient and automatable alternative.

Technological approach within the consortium

The underlying concept was jointly developed as part of the SISSY consortium, funded by the BMWE. Power Plus Communications is making a key contribution through the development of software and hardware solutions for the iMSys infrastructure and the integration of standardised communication protocols.

Established technologies and standards are used. These include the EEBUS protocol in combination with WAN protocols such as CLS-EEDI or the DIN VDE V 0418-63-8 (COSEM-XML) standards. No new software development was required, which represents a clear advantage in terms of feasibility and scalability.

Testing under real-world conditions and validation of the approach are being carried out in stages. Following successful tests in the TMZ laboratory environment in Erfurt, the method is currently being tested under realistic operating conditions. Further project phases will involve tests with real installations, including operational photovoltaic systems at the TMZ in Ilmenau.

The aim is to comprehensively demonstrate the practical suitability of the digital controllability check and to create a robust basis for widespread use.

Advantages of the digital controllability check

• Proof of controllability in accordance with Section 12(2b) of the Energy Industry Act (EnWG) for controllable generation plants.
• Functional verification of the installed control technology and infrastructure for controllable consumption facilities in accordance with Section 14a of the Energy Industry Act (EnWG).
• Use of existing interfaces such as EEBUS, CLS-EEDI and DIN VDE V 0418-63-8 – no new infrastructure required.
• No feed-in losses due to test-based curtailment of renewable generation plants.
• Significantly reduced effort in carrying out the annual controllability check.
• A useful complement to existing physical testing methods.

With the digital controllability check, PPC is making an important contribution to the further development of regulatory requirements and the practical implementation of the energy transition as part of the SISSY project. The approach demonstrates how existing infrastructure can be used intelligently to meet new legal requirements efficiently and in a future-proof manner.

In a detailed white paper, the SISSY consortium has compiled the research questions, findings and test conditions relating to the controllability check.