Arnoldstein 1, Austria - 10.3 MW / 20.6 MWh

NGEN built the battery at Arnoldstein-Gailitz in Carinthia as its first battery storage project in Austria. Eight Tesla Megapack units provide 10.3 MW of power and 20.6 MWh of storage capacity. The system was integrated into the grid at the end of August 2023 and went live in September 2023. At that point it was the largest battery storage system in Austria and the first Tesla Megapack installation in the country.

The battery is a standalone asset on an industrial site and is not tied to any generating plant. NGEN chose the location because it is an industrial site served by the nearby Gailitz substation, which supplies local consumers with around 14 MW. The battery connects to the grid through the same substation.

From the outset, the focus was on supporting the Austrian transmission grid. Within its first months of operation, the battery was integrated into NGEN's portfolio and prequalified with Austrian Power Grid (APG) to provide automatic frequency restoration reserve (aFRR).

As wind and solar take a larger share of generation, the grid has to absorb surplus output when production is high and draw on stored energy when it falls. Frequency deviations have to be corrected within seconds, and the capacity that does this has to be available around the clock.

Batteries suit this role. They respond almost instantly, switch between charging and discharging without start-up time, and can be sited where the grid needs them. Before Arnoldstein, Austria had no large-scale battery providing these services, and the project was the first investment of its kind in the country.

Connecting the battery was only the first step. To take part in the balancing market, the plant had to pass APG's prequalification and then deliver on every activation. That called for software able to bid, dispatch and monitor the battery continuously.

The eight Megapack units set the physical limits: 10.3 MW for two hours. The units use lithium iron phosphate (LFP) cells, a chemistry chosen for its safety profile. Everything else is a decision about which product to serve and when.

The battery is part of NGEN's portfolio and runs on the company's own software platform. The platform offers the prequalified capacity to APG for aFRR, follows APG's activation signals and uses the remaining flexibility on the electricity market.

APG joined PICASSO, the European platform for exchanging aFRR balancing energy, in June 2022. Balancing energy from the Austrian control area can therefore be shared with the other transmission system operators on the platform.

The battery is supervised around the clock from NGEN's dispatch centre in Žirovnica, Slovenia, just across the border from Arnoldstein.

Austria's largest at commissioning

With 10.3 MW and 20.6 MWh, Arnoldstein was the largest battery storage system in Austria when it went live in September 2023.

First Tesla Megapack system in Austria

The project brought Tesla Megapack technology to Austria for the first time.

aFRR for APG

Within its first months of operation, the battery was prequalified to provide automatic frequency restoration reserve to Austrian Power Grid.

Expansion planned from the start

An expansion was already in planning in 2023. It followed in 2025 as Arnoldstein 2, which more than doubled the site.