New Zealand nanotechnologist Brendan Kayes, who has worked at Silicon Valley company Alta Devices since 2009, is developing solar cells so efficient and lightweight they increase battery life on mobile devices by up to 80 per cent.

Using the solar technology being developed by the company, mobile devices would still require a battery to be charged from a wall outlet, but could also be charged by leaving them in full sunlight.

"We are already producing chargers of various kinds, but not yet for retail sale," Dr Kayes, who studied physics, mathematics and philosophy at Auckland University, said.

A engineering scientist and senior engineer at Alta Devices, Dr Kayes hopes the technology will be available to consumers as soon as 2015.

The company has already built prototype solar cases for iPhones and the Samsung Galaxy S3, and the technology could easily be applied to other smartphones.