The South Australian Liberals have pledged to fast-track a new interconnector to New South Wales, subsidise household batteries and scrap a state-owned power plant in favour of a capacity market if elected to Government.

The centrepiece of the Liberals' energy policy is a $200 million interconnection fund, to expedite delivery of new interconnection between South Australia and the rest of the National Electricity Market — with a new interconnector to New South Wales identified as the top priority.

The state's transmission network provider Electranet is currently undertaking a study into options for new interconnectors, which are expected to cost at least $500 million.

Opposition Leader Steven Marshall said modelling provided to it by ACIL Allen Consulting showed the average household bill would fall by up to $302 a year by 2021/22 under the Liberal plan.

If elected in March, the Liberals said they would create a $100 million household battery fund, which would provide means-tested grants averaging $2,500 to 40,000 homes to help them buy batteries.

Applicants would be means tested.

"Plenty of people have invested in solar [systems] on their roofs [in South Australia]," Mr Marshall said.

"What we don't have is the ability for most people to access adequate storage to be able to use that energy when they need it.

"Storage has been left alone by this Government at the household level.

"We want to create that storage opportunity for them in their households, but we also think this can create some opportunities down the track for the producers to be storing that energy and pushing it into the grid when the prices are high across South Australia.

"That will increase the return on the investment they have made."

The State Government announced its $550 million energy plan in March.

Labor's policy 'has been a disaster' for SA

Mr Marshall said he had been "very focused on developing" the Liberal Party's policy over recent months.

Steven Marshall is pledging to fast-track a new interconnector to New South Wales. ( ABC News: Martin Davies )

"We don't shy away from the fact that we've taken the time to get this right, unlike Labor with their kneejerk reactions," he said.

"The reality is, Labor's plan has delivered the least reliable, most expensive power in Australia and it's been a disaster for this state."

Mr Marshall said a Liberal government would proceed with the state Labor government's lease of nine diesel generators to provide backup capacity and prevent blackouts over the next two summers.

But, he said he would not proceed with an option to purchase the generators and transform them into a permanent taxpayer-owned 276 megawatt backup plant.

Instead, a Liberal government would pay operators of private generators to provide backup capacity.

Eastern state companies will put SA last: Premier

Premier Jay Weatherill said the Opposition's new energy policy would put South Australia's future in the hands of east coast power companies.

Mr Weatherll said building an interconnector was a bad idea.

"The South Australian energy plan that we put in place is about taking control of our energy future," he said.

"What Steven Marshall wants to do is give control of our energy to east coast companies that always put South Australians last."

The Australian Energy Council's chief executive Matthew Warren said the proposed shift away from a state-based renewable energy target towards a national approach was consistent with recommendations of the recent Finkel Review into Australia's energy system.

"The SA Government shouldn't need to support new energy investment if we get the national policy settings right," Mr Warren said.

"That is money that can be used more effectively in the state."

But Mr Warren said the industry did not support money being spent on building another interconnector.

"Without a national plan, an interconnector to NSW could make electricity market conditions worse in SA, not better," Mr Warren said.

"Electricity interconnection has an important role to play, but these are expensive, strategic assets that need to be carefully considered."

The Australian Energy Council agreed that the opposition's interconnector plan could be risky.

"You could do more harm than good, as generators in New South Wales using coal with lower costs - just to undercut the South Australian generators...undermine the stability of the grid there," the council's Matthew Warren said.