They don't work. 
I got the little versions, and they work fine, but the big ones don't work. I made sure the switch was on, the solar panels are directly at the sun (and were literally right next to the smaller ones) and they don't work. I waited until we had a few very sunny days and they still don't work. They're out of stock - not worth buying, especially if you have to assemble and wait to see if they work and then you can't return them. Waste of $$, don't do it.