Backpacks are useful items but they can be made more so with the addition of a couple of solar panels. The EnerPlex Packer does this with an integrated solar panel on its rear that is capable of charging smartphones in less than three hours.

The backpack is your standard polyester built carrier the solar panels output 3.0 watts and 5 volts of power. The two main sections sport smaller areas inside and a padded sleeve for a laptop. The side pockets fit water bottles. There is also a waist strap.

Behind the solar panel is a USB port. Hidden away in one of the pockets is a cable that connects up to this port and features a mini and micro USB as well as the old-style iPhone/Pod/Pad cable. iPhone 5 and more recnt iPad users would have to bring their Lightening cable with them to charge up those devices.

The style would be more suited to an outdoors-type of person that would spend all day out in the sun. We found that to get the most out of the backpack, we connected the solar panel up to a rechargeable battery. That way it was more convenient to use as the battery could be charged up in short bursts.

The Packr costs around £79.99, which is expensive for a backpack but could do its bit to save the environment and a bit of cash when using electricity.