Confectionery maker Mars, one of Australia's biggest manufacturers, will shift entirely to renewable energy in just over a year as part of a company goal to reach carbon neutrality from its global operations by 2040.

The maker of the Mars and Snickers chocolate bars and food brands such as Uncle Ben's rice has signed a 20-year power purchase deal that will support development of the Kiamal Solar Farm near Ouyen in northern Victoria, due for completion in mid-2019. It will also support a second renewable energy project planned by the developer, Total Eren, in NSW.

Barry O'Sullivan, a Mars General Manager, at the firm's Wodonga factory.

The move by the company, which runs six factories and two sales offices around Australia, is part of the Mars group's $US1 billion ($1.34 billion) global investment to reduce its environmental impact.

“We’ve got a pretty big footprint on this planet," said Barry O'Sullivan, a Wodonga-based general manager for the company. "Our energy usage in total is equivalent to a small country's.”