This works good as long as it is in full sun. One little shadow and it is done.

I was hoping for a cordless bubbler solution for my smaller/shallow birdbath and this solar-powered small one is great. It does NOT store energy in a battery. Direct sunlight = ON; Shadows, sun low on horizon, etc = OFF. In sun, it will even try to run outside of the bath! So, shade it when you move it for cleaning, etc. It also should come inside over cold nights until the weather surely stays well above freezing all night. This unit has suction feet on the bottom, but my birdbath is concrete so the unit just rests loosely in the center of the bowl. Small birds can still get a bath without bumping it out of place, but larger birds can't. For me, the top spout will bubble water with or without the extension pieces; on windy days, I use no extension so the water doesn't accidentally shoot out of the bowl! I'm so pleased! My patio was lacking the sweet sound of water, and now I can hear it :)