Solar Chicken Coop

I think the answer to your question is to use solar thermal hot water.  All you will need is 1 thermal panel (water), a tank (heat exchange/storage), a radiator for the coop, a small 12v pump and 2 sensors (coop and panel temp).  You would also need a solar panel and battery for the pump (and lights) but far smaller then the electric heat option.  For the low temps use a non-toxic antifreeze in the system and realize that your system will not have pressure (like city water pressure) so leaks should be minimal.  The tank is to be insulated above what it has now but will give heat for days.  If you like to tinker a bit then maybe you could add a fire place water heater - heat water in pipe inside wood stove and splice to in/out going pipes to the tank.  The temp sensor in the coop regulates the amount of heat.

As far as light - I would go with LEDs.  I would use a 25 LED unit (www.ledlight.com/detail.aspx?ID=220) part # 64985 in super white (500k) which is as close to true sunlight as you can get without actual sunlight.  LEDs are expensive but have no flicker (animals can see flicker) and last far longer than anything else.  You will have to use a series of these so take advantage of the bulk discount.  These LEDs have automotive connectors and I get the matching holder (www.autolumination.com) so I can "change" one out (desk lamp white LED to red) or in case one is bad then you have not "modified" it and can return it for replacement.
Actual sunlight could be used of course (without windows) if you put in fiber optics.  Just run some fibers from the "ceiling" to the outside (side wall exit avoids roof holes).  Use small pieces of clear plastic that are finely sanded for diffusers at the end of each "light pipe" at the ceiling.