I live in Southern California and am planning on putting a solar fountain in a very sunny part of my backyard. My question is, how long will it run for? Will it run constantly provided there is bright sun shining on it, or will it juice up, run, then stop until it juices up again? Or does this depend on the kind/quality of solar panel? Thanks.

It depends on the storage capacity of the solar product, the quality of the solar panel and of course, the amount of sun you get.