Construction starts on Green Turtle, Belgium's biggest battery: 640 Tesla Megapack 3s on an old zinc works

Belgium's largest battery project is under construction. Developer GIGA Storage has started building Green Turtle, a battery park in Dilsen-Stokkem in the province of Limburg, close to the Dutch border. Tesla is not only supplying the batteries but also building the site.

The key facts

• Power: 700 MW.
• Storage: 2,800 MWh, or 2.8 GWh.
• Batteries: 640 Tesla Megapack 3 units with cobalt-free LFP cells.
• Site: the former zinc factory of the Société Anonyme de Rothem on the Rotem industrial estate, which operated for nearly 60 years.
• Grid: a direct link to Belgium's high-voltage grid through a new 380 kV substation that grid operator Elia is building next to the site.
• Timeline: earthworks began in mid-August; commissioning is planned for the end of March 2028.

Tesla's role

Tesla is the EPC partner: it handles engineering and construction, supplies the Megapack 3 units and will look after maintenance for the long term. Tesla in turn hired Belgian firm Stadsbader Contractors for the civil works. After the earthworks and roads come the battery installation, cabling and high-voltage work.

The Megapack 3 is Tesla's newest grid battery, with about 5 MWh per unit. That is about 30% more than the 3.9 MWh of the Megapack 2 XL it replaces.

What it will do

Green Turtle will store electricity when there is plenty of it, for example on sunny or windy days, and feed it back when demand is high. Its capacity will be offered to Elia and to market parties for balancing the grid and easing congestion. At full output, GIGA Storage says it can cover the daily electricity use of about 385,000 households.

The developer also expects the park to avoid about 665,794 tonnes of CO2 a year, comparable to roughly 250,000 petrol cars, once the emissions from construction have been offset six months after commissioning. Those are the developer's own estimates.

The site is getting a green makeover too: around 26,650 m² of native planting, concrete that absorbs CO2 as it cures, and a protocol that moved local toads to a nearby pond.

Belgium becomes a Megapack market

Green Turtle is not Tesla's only big project in Belgium. In May, installer SPIE announced it would build a battery park of nearly 700 MWh for developer Storm in Ruien, Kluisbergen, on the site of a former power plant, using 180 Megapack 3 units. That project is valued at more than €100 million, with installation starting in November 2026 and commissioning by the end of 2027.

Green Turtle is about four times as large. GIGA Storage closed €450 million in financing from a group of ten international banks for it this summer.

Why it matters

Belgium is adding more solar and wind power, and that makes flexible capacity more valuable. Large batteries can respond in fractions of a second, which makes them useful for keeping the grid stable. For Tesla, a 2.8 GWh project where it supplies, builds and maintains everything is exactly the kind of full-service deal it wants in Europe, where Chinese battery makers compete hard on price.

What to watch next

• When the first Megapack 3 units arrive on site.
• Progress on Elia's new 380 kV substation, which the project depends on.
• Whether more Belgian and Dutch projects choose Tesla's Megapack 3.