Victoria must come to the table and help prevent widespread blackouts on extremely hot days this summer, the federal energy minister has declared.
More than one million Victorian households could be left without power if an early heatwave hits the state, the Australian Energy Market Operator has warned.
It pins the problem on a coal-fired station at Loy Yang and a gas-fired plant at Mortlake, which are both months away from being repaired.
"If both power station outages were extended over the summer, and if no additional supply was secured, involuntary load shedding may be experienced in Victoria during extreme weather events," AMEO said.
This could lead to between 260,000 and 1.3 million households being left without power for four hours.
Other states within the national electricity market aren't expected to experience such problems this summer.
In NSW, this is partly thanks to the Liddell coal-fired power station being kept open for longer than expected.
Federal Energy Minister Angus Taylor praised AGL for extending the life of the ageing coal asset.
Mr Taylor wants the Victorian government to step up to the plate.
"We need similar levels of collaboration from other state governments including Victoria," he told reporters in Queensland on Thursday.
"If the Victorian government continues to insist it can knock down coal-fired power stations and replace them with solar and wind, which hasn't got the backup to keep the lights on and keep prices down, then they need to be held to account."
Victorian energy minister Lily D'Ambrosio said the state government did not own the power stations and the generators could only give estimated repair times.
"The problem is when you have a look at the record of the failures of some of these old generators, the dates they say they'll come back is becoming less and less reliable and they're getting pushed out," she said.
She said national rules should be changed to allow AEMO to make contingency plans.
"If the market operator was allowed to sign three-year contracts it would cost us the same amount of money as we're doing now for one single year."
In the longer term, an extra five gigawatts of committed new power generation projects over the next three years - most of which involve renewable energy - will only make a "limited contribution" to meeting demand during peak hours, the AEMO report said.
AEMO chief Audrey Zibelman said the outlook report showed the need for "urgent action and prudent planning and investment" to deliver affordable and reliable power.
She said it was not sustainable or cost-effective for consumers and businesses to "reactively" secure extra electricity resources to meet peak summer demand.
"A more measured course is to take a number of deliberate actions that address the challenges of our ageing coal fleet and which meet the need for secure and dispatchable supply, whilst also taking advantage of Australia's natural resources," she said.
Further action could include a new "reliability standard" which ensured each region has enough power to meet peak demand requirements 90 per cent of the time - a standard used internationally.
Also needed was the acceleration of upgrades and construction of interconnectors and transmission to enable better use of existing and new supply resources.
Acting Labor leader Richard Marles places blame for the blackout risk at the feet of the federal coalition, which had put forward 16 different energy policies since 2013
"We have an ageing electricity grid which has suffered from a lack of investment in it," Mr Marles told reporters in Brisbane.
Australian Associated Press