Could battery-powered homes be the future?
Tesla Motors, the US company which makes electric cars, has unveiled a new battery that it says can power homes using solar panels.
It claims that a home battery could change the world's entire energy infrastructure, allowing home-owners to have electricity without relying on the National Grid.
In the UK, there have been government trials using solar panels and a battery pack to create domestic electricity.
Industry correspondent John Moylan went to a home in west London to see how it works.