The total cost of emergency generators secured by the former South Australian Labor government could surge to more than $600 million, the state government says.
An independent report into the lease and upcoming purchase of the generators has been tabled in state parliament with the government describing Labor's decision as an expensive election stunt.
But Energy Minister Dan van Holst Pellekaan says the government won't move to sell them off but will seek to lease them out for 25 years to ensure they are only used to provide cheaper power for SA consumers.
"In all likelihood, these generators will not be needed for emergencies into the future and by leasing them for 25 years they can help deliver more affordable and reliable power," Mr van Holst Pellekaan said on Tuesday.
"By leasing these generators it means they will actually be used and not sit idle while also preventing South Australian taxpayers from bearing the full $609.5 million cost over the lifetime of these assets."
Opposition Leader Peter Malinauskas said the government was essentially privatising the publically-owned power plant.
"The Liberals are simply addicted to privatisation," Mr Malinauskas said.
The independent report put the cost of buying, operating and maintaining the generators over their 25-year lifetime at $494.5 million in addition to the $115 million cost to lease them for the first 13 months.
Investigator Mark Livesey said the government was contractually bound to go ahead with the purchase, with the $227 million bill due to be paid in November.
He also found there was "sparse" evidence in favour of the government owning a permanent, emergency electrical generation facility.
"A recent review of the National Electricity Market apparently shows that load-shedding events have occurred infrequently and, typically, last less than one hour," he said.
"The generators the subject of this report were therefore forecast to operate only a few times each year and then for short periods."
The generators, which can supply up to 276 kilowatts of power, were part of the former government's $550 million energy plan developed after the 2016 statewide blackout.
They are currently installed at two locations in Adelaide but are due to be relocated to a single site within a year or so.
Labor's energy plan also included construction of the world's biggest lithium-ion battery, incentives for more gas-fired electricity generation and support for alternative energy projects.
