Inventor Knut Karlsen has done this at home and teaches us how to do it. He installed photovoltaic cells in rechargeable batteries, which allow these batteries to be continuously charged, particularly when exposed to direct sunlight.
This solar charger is still relatively weak, but its inventor has plans to improve his project to recharge batteries in a more efficient way and to include a device that notifies users when the battery if fully charged.
Find out more at SunCat, Karlsen’s website, and check out his flickr photo gallery on the project.

Rodrigo Barba