(Pocket-lint) - Fossil has launched the first watch series in a new breed of eco-friendly sustainable watches called Fossil Solar. It's a watch built using sustainable materials and recharges using energy converted from sunlight.

This watch was born out of an aim by Fossil to meet its own 'pro-planet criteria' by 2025. Specifically, that means all of its products will include at least one material that's sustainability-approved and will ship in fully recyclable and/or reusable packaging.

The outer ring of the watch case acts like a solar panel, according to Fossil, with a solar cell placed underneath for converting that light into energy which is then stored in its rechargeable battery.

Once fully charged, the watch battery can go up to four months before needing a refill.

Design wise, it's a fairly basic but attractive-looking round analogue watch with a white hands and markings on its contrasting black dial, plus a single rotating crown on the right edge.

The casing is built from plastic, which is paritally bio-plastics made from castor oil. Then there's the strap. Or, more accurately straps. Each watch ships with five different coloured pull-through straps, and each is made with yarn spun from discarded plastic bottles.

If that wasn't enough, the watch ships in a fully cardboard box which you can either to store your straps in, or recycle. No non-recyclable plastics in sight.

The Fossil Solar is available from mid-May, and comes in two sizes: 36mm and 42mm and both cost £129 in the UK or €149 in Europe.

Writing by Cam Bunton.