South Australia's ambitious subsidised home battery scheme has apparently lost its spark, with figures showing just a handful of households have taken up the offer.

Key points: Only 3,700 households have so far applied to be part of the SA Government's battery scheme

Only 3,700 households have so far applied to be part of the SA Government's battery scheme An energy expert believes the high cost of batteries is the reason for the slow uptake

An energy expert believes the high cost of batteries is the reason for the slow uptake The Government remains confident of reaching its target of 40,000 homes over four years

For the past 12 months, the SA Government has offered households $6,000 towards a battery, as well as access to low-cost loans to install solar panels.

But so far only about 3,700 have applied, with only 2,000 batteries installed — significantly less than the target of connecting 40,000 households over four years.

So, in a state known for blackouts and energy instability, why has the battery scheme gone flat?

Energy analyst Tristan Edis said batteries were still too expensive for most households.

"Even taking into account the rebate, you generally don't get a particularly good payback," he said.

"At best, you'd be getting a payback at around eight years. And that's not an exceptional financial investment and for a number of households it would be worse than that."

Mr Edis, who works for Melbourne-based Green Energy Markets, said another reason was that feed-in tariffs to export solar energy back to the grid were still relatively generous — about 15 cents per kilowatt hour.

"The price to export power at the moment is quite high and people are kind of happy, they're making good money exporting electricity and they think 'why do I need the battery?'" he said.

More than 2 million Australian households have rooftop solar, including 31 per cent of homes in South Australia, according to the Clean Energy Regulator.

But only one in every eight homes is adding a battery, according to the Energy Security Board.

Mr Edis said there was a general feeling that battery costs would come down over the next few years, making them an even harder sell.

"People are sitting on the fence waiting. That's why they aren't enthusiastically adopting batteries," he said.

Government confident of reaching uptake target

SA Energy Minister Dan van Holst Pellekaan said batteries were becoming cheaper and subsidies made them an even more attractive option.

"We've developed it so as many South Australians can benefit from it," he said.

"We knew that it would start off slowly, we knew it would pick up pace and that's exactly what's happening.

"I'm confident that at the end of the four years we will get to the 40,000 batteries."

However, Opposition energy spokesman Tom Koutsantonis has criticised the rollout of the scheme.

"Little money has been spent on advertising the campaign and too little in subsidies means the batteries are still too expensive for many South Australians," he said.

$18,000 investment 'made good sense'

The majority of people taking up the offer live in Adelaide's northern suburbs, and Andrews Farm resident Jon Paynter has been one of the early adopters.

Andrews Farm resident John Paynter believes his battery will pay for itself. ( ABC News: Lincoln Rothall )

He said he and his wife Brenda had not paid an electricity bill since they upgraded their solar system and installed a new battery in November last year.

After receiving a $5,000 subsidy, the system still cost them $18,000 — but Mr Paynter thinks it will be worth it.

"I thought it made good sense. After paying $600 per quarter for electricity, it will take me seven years to get my money back," he said.

The SA Government wants more people like the Paynters to speak out about the benefits of solar power connected to a battery.

"The early adopters of home battery storage are already seeing the ongoing benefits and their stories will be the greatest testament for others considering making the same investment," Mr van Holst Pellekaan said.

With the surge in solar showing no sign of slowing, Mr Edis thinks batteries will become more attractive to consumers in the next few years.

He expects excess solar energy generation during the day will cause feed-in tariffs to fall, making a battery a better financial option.

"When you see feed-in tariffs of 4 or 5 cents a kilowatt hour, then I think you'll start seeing people responding far more enthusiastically to that Government rebate," he said.