“Cover the whole roof:” Home solar systems are getting much bigger, here’s why

Not that long ago, the advice many rooftop solar installers were giving their residential customers was to install just enough panels to meet the household’s average electricity demand – unless there were plans for a battery, too.

For some time, this meant the average residential solar system size across Australia was sitting at 6.6kW, and somewhere around that number tended to be where quotes for new rooftop systems would fall.

Not any more.

Rooftop solar systems are getting bigger, shifting the average system size to north of 8kW for Australian households for almost a year now, according to data from leading industry analysts SunWiz.

And it’s not because households are bigger or using more energy, per se, but rather that they are – or at least, soon will be – using more electricity, as homes shift away from costly gas powered appliances and petrol powered cars. And they want less of that electricity to come from the grid.

It’s a trend that PV giant Trina Solar singled out earlier this year at the launch of its Vertex S residential rooftop modules at the Energy Next exhibition in Sydney.

“Households here are moving towards larger system sizes,” said Todd Li, president of Trina Solar Asia Pacific, at the module launch in mid-July.

“A 6.6kW system is no longer sufficient to meet some households’ energy needs. Households need more energy for electric vehicle charging and for heating and cooling.

“With electricity from the grid becoming more expensive, households want to reduce their dependence on the grid completely.

“This is now the priority for many Australian households rather than maximizing rebates available under the STC scheme.”

Residential solar guru and co-founder of Solar Analytics, Stefan Jarnason, agrees. And at the Clean Energy Summit in Sydney in July he called on installers to get with the program and go big on PV quotes to customers.

“We need to encourage covering the roof with solar,” Jarnason told the conference.

“Every single solar system quote I have reviewed over the past four months – and I do multiple every week from companies all across Australia – the systems they’re proposing are sub-optimal for the customer because they’re too small.

“We have interviewed our customers, and about 90% of them when we ask what would they do differently say install a bigger solar system.

“They’re about to switch away from gas to electric and … they’re soon going to add in electric vehicles, so their energy use will double, which means they need a still bigger system.

“So again, I’m gonna say cover the roof with solar, electrify nearly everything, and make sure it’s smart.”

Sophie Vorrath

Sophie is editor of One Step Off The Grid and deputy editor of its sister site, Renew Economy. Sophie has been writing about clean energy for more than a decade.