The government is on track to meet its target of sourcing 100 per cent renewable electricity by 2020, with the last of its big providers - stage three of South Australia's Hornsdale wind farm - expected to start feeding into the grid from October 1.

After legislating a permanent 100 per cent renewables target earlier this year, the government has now turned its attention to shoring up its green energy supply beyond 2020.

Minister for Climate Change and Sustainability Shane Rattenbury said the government would call for bids in a new energy auction in mid November.

In previous "reverse auctions", proponents of wind and solar projects have competed to supply the territory with energy in exchange for feed-in tariffs.

The government will be seeking up to 250 megawatts of new generation in the latest auction, which could come from wind, solar, solar thermal, hydrogen or wave energy projects.

In addition to the energy generation, Mr Rattenbury said the successful bidder would be required to build a battery storage facility in the ACT.

The battery would have a total generation capacity of 20 megawatts, and 40 megawatt-hours of energy storage.

That would be enough to power 25,000 "typical" homes for two hours.

Mr Rattenbury said the battery would help stabilise Canberra's electricity network, providing a reliable source of power to stave of blackouts during periods of high demand or when fossil fuel generators failed in heatwave conditions.

"With more and more renewables coming onto the market, we do need to make sure that we are starting to put in place technology that will deal with their intermittent nature," Mr Rattenbury said.

Mr Rattenbury said Tesla's 100-megawatt battery in South Australia - promoted as the largest of its kind in the world - had shown energy storage technology had a range of benefits.

"It doesn't just provide power during blackouts and alike, or potential blackouts, but also a range of ancillary services around stabilising the grid," he said.

Mr Rattenbury expected the successful bidder would be selected early next year, with contracts to be signed by mid-2020.

He said based on government modelling, the extra 200-250 megawatts to be delivered through the latest auction would shore up Canberra's electricity supply until the "middle to later part of the next decade".

The need for further reverse auctions, and more energy, would be determined by the demand for electricity as the city's population grew.

"It will depend a bit on how things electrify," Mr Rattenbury said.

"If we suddenly see a large transition to electric vehicles then [the new generation] might not last as long and we may have to go to another auction sooner."

News of the new auction, to be announced on Thursday, comes as the ACT government prepares to unveil its new climate action strategy in the coming days.

The strategy will outline how the government will help drive the "decarbonisation" of the Canberra region up to 2025 and beyond, Mr Rattenbury said.

He said the timing of the two announcements was coincidental, though he acknowledged they both progressed the ACT's vision for a low-emissions future.

"We have a legislated target to reduce our emissions by 50-60 per cent by 2025 and a key part of that is electrifying because transport and gas will be our two biggest sources of emissions," Mr Rattenbury said.

"Between them they will account for more than 80 per cent of the ACT's emissions."