Contact Energy has teamed up with electric car company Tesla to build a grid-scale 100-megawatt battery at Glenbrook, at a cost of up to $163m. 

The company said the battery would enhance Contact’s renewable-energy flexibility and provide enough electricity to meet peak winter demand for 44,000 homes for more than two hours. 

The battery will be sited next to NZ Steel and Transpower’s grid connection point, and will be closer to Auckland load than any other grid-scale battery project. 

After a competitive tender, Tesla had been selected to supply its Megapack 2 XL battery energy storage system and to provide commissioning and long-term maintenance services. 

The agreement with Tesla includes an option to expand the capacity for the battery to 130MW at this site. 

Contact will manage the project overall and will start construction at the Glenbrook site immediately. 

Contact continued to advance further battery investment options and had been granted consent to build another 100MW grid-scale battery in Stratford, Taranaki, it said. 

The battery at Glenbrook is expected to be on line in the first quarter of 2026. 

Once operational, it would provide Contact and the market with an important source of renewable electricity flexibility, operating across physical, reserve and frequency-keeping markets, the company said. 

Contact’s move follows a groundbreaking decision on May 31 from NZ Aluminium Smelters — the country’s biggest power user — to remain in New Zealand for 20 years after previously threatening to shut the plant down. 

“With New Zealand Aluminium Smelters now confirmed to stay for the long term, providing improved market certainty, Contact is advancing its plans for investment in new intermittent renewable generation across New Zealand,” Contact said. 

The battery would support new wind and solar on an intra-day and intra-week basis and ultimately reduce reliance on gas peakers as Contact transitioned to a low-carbon future, it said. 

Jamie Gray is an Auckland-based journalist covering the financial markets and the primary sector. He joined the Herald in 2011. 

- NZ Herald