A report to be released by the commission on Monday shows more than one in 10 Australians are powering their homes with the sun, with more than a million rooftop photovoltaic systems installed nationally. Solar hot water installations have also taken off as the cost of electricity and gas continues to rise.

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In Canberra, more than 20,000 households and businesses have solar panels installed, with one of the city's least wealthy areas, the postcode of 2615, leading the charge with 1502 systems installed. Queensland had the most installations of any state or territory.

Chief climate commissioner and report co-author Professor Tim Flannery said some of the biggest take-up was in mortgage-belt suburbs.

"It has astonished everyone. If you read the old energy white paper of 2009, it predicted we'd have about as much solar as we have today by 2030, so to get it that soon is pretty amazing,'' Professor Flannery said.

"The most significant factor has been the decline in cost. The manufacturing cost scale is so effective that you can now buy panels at a quarter of the price that you would have paid for them in 2002."

The report predicted solar PV would account for about 29 per cent of Australia's energy needs by 2050. Australia has the world's second-largest solar resource, with China's bigger landmass giving it the greatest potential. Despite this, Australia's 2400 megawatt hours per year of total installed solar capacity ranked only sixth in the world, well behind leader Germany's 32,200 MWh/year.

Professor Flannery said while there had been problems with feed-in tariffs and other issues in the industry along the way, solar was now at a point where it was competitive on cost in many cases with traditional fossil fuel energy sources.

Emerging technologies such as solar thermal were also maturing and becoming more viable.

"You would have said that about solar panels five years ago, too, for 30 years they hadn't gone anywhere, then manufacturing took off. If you watch what's happening internationally, costs in Spain [for solar thermal technology] have dropped 20 per cent over the last four years, and these are large-scale plants."

Investment in solar globally also overtook wind power for the first time last year, and accounted for more than 57 per cent of renewable energy investment.

With only 10 per cent of Australian households connected to solar-powered systems, Professor Flannery said there was plenty of scope for continued expansion in Australia.

"The key is stable policy settings. Stop-start programs are annoying for business," he said.