Huge amounts of energy were withheld from the South Australian market during a power price spike in July, a new report says.

The State Government was forced to plead for more electricity from a private power station as prices hit $14,000 per megawatt hour.

The report was commissioned by activist group Get Up and claimed about a third of the state's power capacity was withheld while only a small amount was released at very high prices.

Researcher Bruce Mountain said there was plenty of power capacity and about $42 million was gouged from the market.

"I estimate that if prices were matched to the highest cost of a very high cost generator at the time, on the 7th of July, over the peak periods, it would've generated $5 million," he said.

"In practice on that time period it actually gave a total of $47 million."

Australian Energy Council chief executive Matthew Warren denied companies were manipulating the market.

"We have a problem when we have lots of abundant generation some of the time and not enough generation other parts of the time, and that's a problem we need to fix," he said.

"This is not about oligopolistic behaviour.

"This is about getting the market settings right and the solutions in place so we can continue this transformation, but this is not a conspiracy."

South Australia's high energy prices will be discussed at a COAG meeting in Canberra on Friday.