I have an addiction to solar gadgets and rechargeable batteries. So when you combine the two you have a winner in my book. This unit costs less than $24 at Amazon, and charges D (UM-1), C(UM-2), AA (UM-3), and AAA (UM-4) size batteries. The solar panel is built into the hinged lid which allows you to angle it for maximum sun exposure. The analog meter shows you the following conditions: -The strength of the sun, the strength of the current out-put from the solar panel, and the time required to fully charge the different types of batteries.