Can't decide whether to install solar panels?

A new tool is making it easier for households to make the call whether to go solar or not.

It shows the best spots to install panels on the roofs of half a million homes across Auckland. 

Like most parents Hugh Robinson is looking at options to reduce the family's power bill. 

"Definitely the financial reasons would be some reason we'd look at solar as well as the environmental aspects," Mr Robinson says.

Mr Robinson and his wife are looking to renovate and they're looking at the possibility of installing solar panels.

But getting data on whether that's cost effective for his place in Mount Eden is tricky.

"It's thousands of dollars probably to put solar in and I don't really have an idea as to how long that would take to pay back," he says.

University of Auckland researchers have created a new online tool that maps 500,000 rooftops across Auckland.

The darker shades show the best spots to put solar panels based on the slope of a roof and whether there are trees.

"So currently new houses you'd often place them facing north and have more simple roof tops and the trees will be less mature so the newer neighbourhoods seem to have a higher potential," Map creator Kiti Suomalainen says.

Households then add details about how much power they use, amount of power consumed during daylight hours and the cost of the panels.

This calculates long-term whether solar is a worthwhile option for a specific house.

"So it's not about just whether you have the money or not it's about whether it will make economic sense," Ms Suomalainen adds.

An extra $1354 in the pocket over 25 years isn't enough for Mr Robinson to make the change but he's hopeful technological advances will see the price drop.

"It feels like in two or three years' time that that would improve, it would be interesting to see what that calculation looked maybe two years ago," he says.

Ms Suomalainen says storing solar power, doing the washing and using other appliances during daylight hours including heating water can make it much more beneficial to use solar.

Newshub.