This system can save $300+ per year in energy costs and reduce CO2 emissions by 2 tons. Full and free construction plans provided below -- it will cost about $1000 in materials. As of late April 2009 we have lived with this system for 8 months. It has been trouble free and provided a solar fraction of 94% over the cold Montana winter. Aside from the failure of an off the shelf controller, it has required no maintenance. The drain back system has seen temperatures down to -30F with not even a hint of a problem. I believe that the system has been and will continue to be the functional and thermal equivalent of commercial systems that seem to be going for around $7000+ these days.