I feel a lot better now that I've gotten the guineas to go into the coop at night. I just added this solar powered light to the coop and now they go in on their own without having me to shoo them off the door. I bought it off eBay:
I let it charge up on my front porch banister all day yesterday and then mounted it at the back of the run and pointed it due south before dark late yesterday afternoon. I turned it on about 5:30 or so just as it was getting dark and everyone went inside for the night. When I came back out at 9:00 the light was still going when I closed the pop door on the coop. It was out when I opened the door this morning at 6:00 to let them out. I need to rig up a longer chain to turn it off because so I don't have to reach inside and scare them off their roosts to turn it off.
Good news, and good idea ... although you could just drill a hole to drop a cord through? You could relocate the power switch or, better still, use a light sensor + a timer, so it's come on when it begins to get dark, 'n go off on it's own (you could pick up one of the cheap led landscaping lights, 'n wire it up as the controller ~'-)