That was partly a result of a widening drought curbing hydro output and trimming total renewable electricity to 17 per cent of Australia's total, versus 17.3 per cent in 2016.

But the bigger story was the 700 megawatts of large-scale renewable energy capacity added last year and about seven times that total either under construction or with financial support, the Clean Energy Council report shows.

Large-scale solar has particularly ramped up, with capacity rising from 34 megawatts in 2014 to 450 megawatts at the end of last year.

Some 50 large-scale wind and solar projects worth about $11 billion were under construction as of last December or scheduled to begin soon, the council said.

So far this year, some 291 megawatts of new solar projects have already been completed, with almost as much due to start exporting to the grid soon.

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Various states are touting their gains, with NSW boasting a pipeline of almost 14,000 megawatts of renewable energy projects worth almost $18 billion in potential investment.

"This is in addition to the over 1200 megawatts of wind and solar farms under construction," NSW Energy Minister Don Harwin told Fairfax Media. "We know the private sector is seeing the opportunities to invest in new energy generation in NSW."

Victoria's first 650-megawatt renewable energy auction, meanwhile, is the single largest renewable energy tender in the country.

While the current boom is driven by the 2020 Renewable Energy Target, which should be achieved at least a year early, the industry is seeking clarity about what comes next.

"Our concern is that the momentum we have at the moment is at risk without strong policy certainty in the post-2020 environment," Mr Thornton said.

That certainty, or otherwise, could be determined in coming weeks as states and territories prepare to discuss the final design of the Turnbull government's proposed National Energy Guarantee targeting affordability, reliability and reduced emissions from the electricity sector.

“The continued investment in more supply is essential to driving down electricity prices," Environment and Energy Minister Josh Frydenberg told Fairfax Media.

"That is why we are working to finalise the [NEG] to not only provide investment certainty to spur on more investment but to also ensure there is enough back-up and storage in the system for intermittent renewables.”

Rooftop solar, meanwhile, has now reached 1.825 million Australian households, the annual report noted. Average systems last year were 6.27 kilowatts, more than double the size in 2012.

Interestingly, about one in eight of the 172,000 PV installations last year included a battery, up from 5 per cent in 2016.

For Father Smith, who has already mustered a couple of dozen willing parishioners to take up solar, storage is not the priority.

"Batteries aren't quite there yet, but they're coming," he said.