I just saw this link posted on FB by https://www.facebook.com/Egg.Carton.Labels.by.ADozenGirlz.
It's a DIY scheme to make a solar pop door from a winsheild wiper motor and a photoelectric cell for a timer.
http://www.earthtechling.com/2011/09/auto-solar-chicken-coop-door-lets-you-sleep-in/...