The state government announced a 300-megawatt lithium-ion battery will be built near Geelong, driving down power bills and creating more than 80 construction jobs.

The Tesla battery will be installed near the Moorabool Terminal Station outside Geelong and is expected to operational by the end of next year.

At 300 MW/450 MWh, it is twice the size of SA's newly-expanded Tesla battery which operates at 150 MW/194 MWh.

Energy, Environment and Climate Change Minister Lily D'Ambrosio said the big battery would cost taxpayers $84 million over an 11-year contract, but deliver double the savings.

"Whilst there is a cost to have that service available, the actual net impact on the bill is a net positive for every Victorian consumer, for every Victorian household and every Victorian business," she told reporters on Thursday.

Ms D'Ambrosio was reticent to put an exact figure on average savings for consumers and businesses, saying it was "in the dollars".

"This isn't about thousands of dollars of savings on an energy bill but the fact is this makes absolute economic sense," she said.

"It is about providing security. It is about providing reliability. It is about ensuring that our renewable energy future is one that people can actually depend on."

Ms D'Ambrosio said the benefits were two-fold, injecting economic stimulus as the state emerges from the "deep recesses of COVID".

The $84 million investment is expected to create more than 80 construction jobs and six full-time positions in the Geelong region.

Construction is due to start within the next fortnight.

Environment Victoria chief executive Jono La Nauze said the battery would be a "game-changer" as Victoria transitions away from coal-fired power stations.

"This big battery gets us halfway to the storage target we need to prepare for the closure of Yallourn power station," she said in a statement.

The Climate Council chief executive Amanda McKenzie labelled it a "smart economic move", citing a 90 per cent drop in battery prices over the past decade.

"It will create clean jobs for Victorians, strengthen the state's clean industries, and lower power bills at a time when households need it most," Ms McKenzie said.

Opposition energy spokesman Ryan Smith suggests the battery is being built in a sub-optimal spot, far away from Victoria's main renewable energy production zone.

"This big battery should be built at Mortlake, as we proposed in June, not at Moorabool," he said.

Australian Associated Press