I bought these lights to go outside at Christmas thinking they would probably not be fantastic this time of year with the dull grey weather we were having. I was wrong!! Even on the dullest days the lights charged up enough to last a few hours in the dark - usually still shining, if a little dulled, by the time I went to bed. It was great not having to worry about turning them on & off or setting up a timer - as soon as it got dark the bright little lights came on and then went off in the light (I had them in the front garden and they would go off if a car's lights hit the sensor, but back on again when it passed). I've now moved them into the back garden, and will leave them there to make a pretty display for the summer, they're too good to only keep for Christmas!