Still in the early prototype stage, SunCat batteries represent a real advancement in battery technology.
Designed by Knut Karlsen, these solar batteries consist of NiMH rechargeable batteries that have been covered with a flexible Photo Voltaic layer.
When the batteries have been fully discharged, placing them in natural sunlight would start the recharge process. As these are prototype batteries, they are more proof of concept and as a result are not the most efficient. The current batteries are able to draw only the smallest of charge from solar energy, but Karlsen is working on a new version of the solar battery that will incorporate capacitors and electronics, thus making it much more efficient.