That's 500 megawatts of solar installed on 20 percent of homes across the South-West Interconnected System [SWIS] region, which includes Perth's metropolitan area, and it's only continuing to grow.
"By 2020 we could have half of Perth's households with rooftop solar," says Curtin University Sustainability Professor Peter Newman. "Despite the boom times we actually reduced our power consumption during this period because people are just not needing it if you've got the PV's [photovoltaic] on the roof."
"We are in the extraordinary position of saying that Perth [SWIS] now has rooftop solar as the largest supplier of electricity, it's the biggest power station in WA."
This has left Western Australia's utility companies in a unique position.
"They didn't predict it," Professor Newman says. "They have all these contracts for coal and gas that go 20 or 30 years and they have even got an old power station out of mothballs, fixed it up, but never turned it on."