South Australians will have the cheapest power prices in the country in as little as six months, energy experts say.

The state already has some of the lowest wholesale power prices as a result of increased gas generation.

But those cheaper prices are not yet being reflected in household bills where rates are set periodically.

Solar Council chief executive John Grimes says if bills don't drop then consumers have a right to demand answers from suppliers.

"If it's not (cheaper) then the question is, why are the big power companies gouging the people," he told reporters in Adelaide on Thursday.

He said about 4500 jobs would be created from the more than $8 billion being invested in the renewable energy sector, which was leading SA away from the dark days of power blackouts to become a net exporter of electricity.

The former chief executive for the Clean Energy Finance Corporation Oliver Yates said increased investment in renewables would also cut household energy costs.

Increased supply naturally drives down price, he said.

"Every new facility that's being built now in South Australia, and they will all be renewable facilities, is going to produce power at a price lower than what is currently being offered," Mr Yates said.

He said the grid price for South Australia was currently about $80 per megawatt an hour, which was higher than the current value of clean energy.

"Wind is somewhere near $50 and solar is now at $60, so if we can get more of that into the grid we will lower that price," he said.

Mr Yates said the coalition government's National Energy Guarantee was a roadblock to driving down costs because of its exclusion of a clean energy target.

South Australian Energy Minister Tom Koutsantonis agreed and said the plan favoured coal-fuelled generation and assumed renewable energy was the reason for the high cost of electricity.

"It's a nod and a wink to the coal industry," the minister told the Smart Energy Summit on Thursday.

But SA Opposition Leader Steven Marshall said the state Labor government had failed to lower energy bills.

"In fact, this year there has been 18 to 20 per cent increase in energy bills for households," he said.