Converting a solar panel (direct sunlight power) to a battery backup system? How to help!?

I want to make solar powered fountain for my husband's birthday. However, we do not get enough direct sun all day to power a "direct sunlight" solar panel. I would like to use a solar fountain pump and add a battery system to it so that the battery will charge and accomodate for periods of shade during the day. (Kind of like how solar garden lights power up all day and then run at night.)

I've seen systems and kits you can buy, but they seem ridiculously expensive and I'm sure this can't be that difficult to do. Can anyone help me out w/ a How To?

I do have a basic understanding of electrical theory and wiring, but I am not an engineer, so please try to keep it simple. (I know about wiring, watts, volts, amps... I can install outlets, fix lights and understand balancing an electrical system to make sure the source is providing enough power and that the lamp won't blow up, etc.... to give you an idea of where I am coming from.)

Thanks!