Fears about rising energy prices have driven consumers and businesses to install solar panels at the fastest rate in at least a decade, lifting total national capacity to the equivalent of powering a city the size of Melbourne.

New figures from the Australian Photovoltaic Institute show the country has passed 6 gigawatts of solar capacity as of the end of March, or enough to supply about 1.3 million households.

"There's been just a huge surge recently on the back of the energy concerns earlier in the year," Renate Egan, chair of the institute, told Fairfax Media.

Total capacity could top 7 gigawatts within a year with a host of solar farms and a rise in companies turning to solar driving the extra demand. That level would be the equivalent of about 1.5 million households' supply, or about Sydney's size.