The innovators: portable solar panels that can be unrolled like a carpet

John Hingley has developed a 'micro-grid' in a metal box that can be used for disaster relief, mining, and even festivals

Talk is not cheap in the mountains of Nepal. Getting a mobile phone charged can cost $5 in areas where there is no electricity and backpackers have to rely on diesel generators used by locals to power up.

John Hingley had a solution stuffed in his rucksack: a thin and lightweight portable solar panel that unfolded and could generate enough energy to power his phone, camera and computer. As well as keeping him charged in the mountains, the simple device commonly used by travellers and outdoor enthusiasts gave him an idea - to make a much bigger version.