I am using a bread board implementation of Arduino. I want to charge it via a solar powered batteries. I am looking for a commercial solution in which I have some reserve battery such as 2000 mAH or more and a automatic functionality that whenver solar power is available,it uses that for power and when it is not then it uses that battery to power the system.
Can you please suggest any commerical products available for this. I want to have a compact one solution for this. Dont want to get in to separate solar panels and other stuff.
Seeedstudio sells a "LiPo Rider" that might be what you're looking for. Sparkfun sells something similar.
TI's LM1117 datasheet shows how to build a battery backed power supply (page 20) that might meet your needs. That circuit should have something added to prevent overcharging the battery (zener shunt regulator, etc.).
LadyAda sells a product that is specifically designed to charge a LiPo battery from a 6V solar panel. As far as I know it is the only device specifically designed for this purpose using solar as a charge source,
At the very least I suggest looking at her design notes for the product, which address some of the drawbacks to using a traditional lipo charging circuit (including her own) with solar.