You may want to look at Technautics.

http://www.technauticsinc.com/

I built a fridge/freezer a few years ago and their system was easy to
install and has run well ever since. I have a holding plate in the freezer
and spill over into the fridge. I can make ice cubes over night and it uses
about 22AH a day.

Ansley Sawyer
SV Pacem