I bought a solar powered rope light and strung it around the inside of the coop. It comes on as soon as it starts to get dark enough and stays on for a few hours after. It's not super bright...just enough to let them get settled in well. It was the best $20 I spent on them They carry them at Lowe's and Home Depot in the outdoor lighting section. You need a pretty bright area to put the solar panel for it to charge up during the day, especially in winter. It doesn't stay on as long in winter either, but long enough to do it's job. My girls that were on their first year actually started laying in about December last year and were pretty productive all winter.
