I recently stumbled across a solar charged watch that someone was throwing away. The brand name is 'And1' and the model number is '50001'. The only other markings on the back are 'Japanese Movement' and a sticker that says 'Made in China'. From the behaviour I've observed (The watch functions normally in full sunlight, fails when the sunlight is removed.) I'm guessing that the rechargeable battery is no longer working.
The backplate is attached by four screws suggesting that the battery may be replaceable, what I'd like to find is information such as a manual. Google searching confirms the watches are for sale via Amazon, but there does not appear to be a company specific website.