Hello, I'm in the planning stages of designing an AP greenhouse.  I live in zone 6b.  My initial thoughts were to build a passive solar greenhouse, in an effort to have a system that is more sustainable.  I'm hoping to use solar panels to generate the electricity needed for the pumps etc..  But for heat I'd prefer to heat with the sun.  This will be an all year greenhouse, I hope.  Approx. size 1…