Susan and Ian Wilson with the battery component of their solar panels. Credit:James Boddington Since installing the system, the household power bill has dropped by two-thirds and the house is now immune from blackouts. The Croydon home is fitted with a 3.6kw solar power system and a 16kw battery system that can be used when energy from the grid is at its most expensive. Mr Wilson, 58, said he expects to get at least 20 years out of the system and it made sense for environmental and economic reasons. "We have used almost no peak hour energy at all since getting batteries ... we did have a power outage in the area and sailed through it, [it was an] automatic switch over," he said.

Solar remains a popular investment, despite the minimum amount power companies must pay back to homes in Victoria for the power they send back to the grid reducing to 6.2 cents per kilowatt hour from the start of January – down from 8 cents. Damien Moyse from the Alternative Technology Association said households should be paid more for their solar power. "We think the answer is more in the 10 to 20 cent (per kw) range of the actual economic value," he said. Mr Moyse said households should be investing in energy efficiency, including insulation, as well as adopting solar. There were almost 167,000 solar power systems installed across Australia last year, with more than 36,000 in Victoria.

"The business case is there now, it makes sense financially, so you are not relying on people to buy solar because they are motivated by climate change or doing the right thing," Darren Gladman from the Clean Energy Council said. "It becomes a question of 'why not'? It saves you money and it is also good for the planet," he said. Recouping the investment for a rooftop solar system – a recent Choicesurvey put the average upfront cost at $8783 – can take between seven and 11 years depending on the size of the unit and household energy usage pattern. While smaller systems of below 3kw have a quicker payback period, there has been a trend towards bigger systems of 4kw and above. Ric Brazzale from Green Energy Trading said economies of scale made the larger systems attractive. He said in 15 years half the detached homes in Victoria could have solar panels.

"If we keep going at the same rate we are going to hit 20 per cent (of homes with solar panels) by 2016 and hit 50 per cent by 2030," he said. Radley de Silva, from the Master Builders Association of Victoria, said solar panels could help first homebuyers grappling with energy bills, and governments should be making homes more affordable and sustainable by rewarding homeowners who install solar energy. But a new Choice survey has warned consumers to shop around to avoid problems with their solar investment. The survey of Choice members found almost one third had issues with their installer and a quarter experienced problems with their systems. For more information see: www.choice.com.au/solarsurvey