As any tech fan will know, the Achilles heel of most gadgets is their battery life. You can have the most amazing device out there but, when the battery runs out, it's about as useful as a doorstop. Enter the Black Hills Solar Backpack, designed with charging in mind.
The Solar Backpack has a solar panel on the front that needs to be left in direct sunlight in order to charge. Charging takes up to 14 hours in sunny conditions, with the backpack then able to supply around 2 hours of power to a mobile phone or MP3 player.
Unlike other solar-powered bags, the Solar Backpack isn't weighed down by tonnes of solar panels. That means it's a lot lighter than most, but charging also takes longer.
Given the UK's distinct lack of sunshine, you'll be glad to know that you can also charge the battery pack via the mains or USB before you leave the house, and then trickle charge it as and when there's sunlight. The bag comes with plenty of adaptors to fit a variety of devices, including iPod, iPhone and mini-USB connectors (full list here).
It's currently available to buy online for around £50 with free delivery, which we think is rather cheap compared to other solar-powered bags.