I am a chicken newbie and we are in the process of building our first coop. We live in the California Bay Area so winters here can drop into the 30's occasionally but winter days are usually in the 50-60's. The coop is 3.5' w x 4' d x 5' H and segmented into 2 floors. We have insulated the siding with 1" styrofoam but we are wondering if it is worthwhile to rig a solar powered light bulb for heat in the winter. We have 3 EE hens this year and possibly add up to 3 hens (other breeds) in the near future. Any ideas on the additional heating source (ie the solar powered light blub) or am I just being over-protective? Thanks!