The largest lithium-ion battery in the world – Tesla's big battery in South Australia – will undergo a 50 per cent expansion in a move its owners hope will increase the stability of the grid and reduce power bills.

Tech billionaire Elon Musk's Tesla built the huge battery in a remote area of South Australia in 2017. The battery system has the capacity of 100 megawatts and can store 129 megawatt-hours of energy from wind turbines nearby – enough to supply 30,000 homes for eight hours.

French energy giant Neoen has announced plans to expand the capacity of the huge Tesla battery installed at the Hornsdale Power Reserve in South Australia by 50 per cent.

The battery system's capacity will now be increased to 150 megawatts under an expansion plan put forward by French energy giant Neoen, the owner of the site, with the support of Tesla and the state and federal governments.

Paired with the adjacent Hornsdale wind farm, Tesla's grid-scale battery, known as the Hornsdale Power Reserve, has helped reduce intermittency and manage increased demand during summer when the grid is under the most strain. In its first year of operation, it saved consumers more than $50 million, according to Neoen.