Google's Project Sunroof can tell you how much money you would save by installing solar panels

Google wants to roll out the eco-friendly service worldwide

Project Sunroof shows users the levels of light and shade on their roof, and tells them how much they would save with solar power

Google has unveiled its latest major new product, Project Sunroof, which aims to make it easier for people to install solar panels in their homes.

Project Sunroof, which has already launched in the US cities of Boston, San Francisco and Fresno, is Google's effort to make solar power simple and understandable.

Simply by entering your address into Project Sunroof's website, Google can show you how much usable sunlight you get per year, which parts of your house get the most sun, how much room you have for solar panels, and most importantly, how much money you would save by switching.

It then shows you solar panel installers nearby, and lets you go straight to their website to order.

The adverts for these companies are sponsored, so this is where Google makes its money.

The idea is simple, but it has powerful technology behind it - running from Google Maps, the roof of your house is 3D modelled, so Google can figure out the details about cost and light levels.

Google wants to make it easier for homeowners to install solar panels on their home (Sean Gallup/Getty Images)

Project Sunroof only works in three cities at the moment, but it's fun to play around with and see how much you could save on your bills if you lived in California.

Google wants to take it across the US, and then across the world, in due course.