If you have chickens, you've probably noticed their egg production dropping off lately. Here's the reason: chickens need about 14 hours of sunlight per day to stimulate their bodies to produce an ovum. Last weekend was the Autumnal Equinox, which means the sun is hitting the earth straight on the equator. You can look up sunrise / sunset times and see that the U.S. is receiving about 12 hours of sunlight per day right now. This will decrease until December 21st, then slowly increase until the first day of Summer.
That shows us that for more than half of the year, your chickens do not receive enough light to make your eggs. Now, chickens are cute and fun and all, but it's really not worth having birds that do not lay. So - let's solve this problem. You will need a electricity, a light of some sort and a timer. That's it!
Your rule of thumb needs to be that the light should be bright enough to read a newspaper. Fortunately, here in the South the sun remains fairly high in the sky throughout the winter. If you have the light come on between 3 and 4 a.m. and turn off about 8 a.m., you will still have enough light even in the shortest days of the year. That is also the coldest time of the night, so a heat lamp will keep your chickies more comfortable.
Let's review - if you choose to have your chickens permanently in a movable pen, you will need to think about supplying electricity somehow from fall to spring. Maybe park them by the house in the evenings and run a GFCI cord? The other alternative is to have a winter house with electricity permanently available and only put them in their movable pen on nice days.
The light you choose is your choice. I chose a simple outdoor flood light with a clamp-on fixture for its durability. I have been known to bump into my light when working around the coop, and I don't want to risk glass shards from a broken light or having mercury from a florescent bulb in the coop.
Pine shavings and chickens droppings on the floor will be breaking down continuously, creating heat. You may need to cover open walls to protect the girls from sharp winter winds, but we have an advantage here in the South because our ground does not typically freeze, so the composting droppings create enough heat for them to get by.
We'll talk later about how to get your girls fresh greens through the winter, so you can still get the benefits of pastured eggs. (see the difference here) As you can see - there's still a whole lot more!