A large blaze at Victoria’s “big battery” project has been brought under control by firefighters after burning for more than three days, allowing investigators to begin examining the site. A Tesla battery bank caught fire while it was being set up in Moorabool on Friday morning, and then spread to a second battery. The fire burned throughout the weekend and into a fourth day, before it was declared under control just after 3pm on Monday. Fire crews will remain at the site for the next 24 hours “as a precaution in case of reignition” and will take temperature readings every two hours, the Country Fire Authority said. Investigations into how the fire started will soon begin with multiple agencies involved, including Energy Safe Victoria, WorkSafe, police and the CFA. The 300MW battery project is being produced by French renewable energy giant Neoen and was registered with the energy market operator on 28 July. Neoen Australia managing director Louis de Sambucy told AAP its own “physical inspections and investigations are now underway”. CFA incident controller Ian Beswicke said the fire had been particularly challenging due to the complex nature of the battery site. Sign up to receive an email with the top stories from Guardian Australia every morning “This is the first mega pack fire that’s ever happened in the world, is our understanding,” he said. “They are difficult to fight because you can’t put water on the mega packs … all that does is extend the length of time that the fire burns for.” Firefighters have taken advice from experts including Tesla, the battery’s creators, and UGL, who are installing the battery packs. “The recommended process is you cool everything around it so the fire can’t spread and you let it burn out,” Beswicke said. The site is slated to become the biggest battery in the southern hemisphere and forms part of a state government push to transition to renewable energy. But the fire has sparked calls for the government to conduct its own probe into what happened before pressing forward. “If Labor’s renewable energy solutions go up in flames even before they’re fully operational – what hope do Victorians have that this government will be able to effectively manage the renewable energy transition?” shadow energy minister Brad Rowswell said. A Victorian government spokeswoman said “full and comprehensive” investigation into the fire was underway by several agencies. “This will span investigations into the basis of the fire, how it started and to ensure the site is safe as a workplace,” she told said. Neoen Australia said there were no injuries to workers and confirmed the site had been disconnected from the grid with no impact to electricity supply.