SMA receives first certificate for grid-forming battery inverter with instantaneous reserve

SMA says its Sunny Central Storage power plant battery inverter is the first in Germany to receive a unit certificate for operating in grid-forming mode by offering instantaneous reserve. The certificate applies to high- and extra-high-voltage connections and is based on the requirements of technical standards VDE-AR-N 4410-20 and VDE-AR-N 4130.

Certification means the inverter can be used in projects aiming to participate in the instantaneous reserve market which will be opened in early 2026, on a non-discriminatory and market-supported basis via a tender process. An tender-requirement exemption that had existed since 2020 because battery inverter based instantaneous reserve technology lacked maturity, was lifted the Federal Network Agency in September 2023.

A guidance document published in June by the Verband der Elektrotechnik Elektronik Informationstechnik Forum Netztechnik/Netzbetrieb (VDE FNN) forms the basis for grid forming inverter instantaneous reserve certification. That document outlined detailed technical requirements including overvoltage behavior, settling times, and numerous other characteristics that grid-forming inverters, storage systems, and customer systems must meet. It was drafted via public and industry consultation.

Instantaneous reserve is the immediate response of a generating plant to voltage or frequency changes in the grid, to keep the system stable at 50 Hz. While the service has previously come mainly from the rotating masses of fossil-fuel power plants, it will come from renewables sites and battery storage systems in future. Instantaneous reserve can be provided on a symmetric basis – providing positive and negative power – or by systems which react only in one direction.

“We are not waiting for new requirements to arise but are already enabling our customers to use grid-forming technologies in the interconnected grid that not only meet existing requirements but can also provide advanced stability services such as the immediately effective instantaneous reserve,” said Daniel Duckwitz, product manager for grid stability at SMA.

The VDE-FNN note, which also covers grid-forming storage systems, controllable reference units, and customer systems, marks the last technical milestone before instantaneous reserve tenders can be held.

From pv magazine Deutschland.