I am one of the hot tub owners that STI helped and I am thrilled with my solar water heating system! Just one panel (2 x 3 m.) and a small circulating pump have the tub at 95 F by late afternoon. [edit] I also use a propane heater to get the tub up to 105 F before I use it, but with the solar boost that takes a matter of a few minutes instead of the hour + it took before, and I use a LOT less propane! ;-) Gracias AngusMactavish. Give Ron Magen an email and see what he can do for you. I