Question Re: Our Solar Water Heaing System
We have a 12-year-old roof panel solar water heating system, heating our floor with pex tubing, (also passive solar southern windows), in North Carolina where it freezes but is usually also sunny. We have gas tankless backup heat, which runs a lot, in fact too much.
Our problem is: Our "storage" tank is a huge old-style water heater. We're paying to keep this water heated even in the dark (non-solar) night. But if we want to switch to an on-demand water heater, to eliminate the waste of that big old water storage/heater, we lose the ability to store the solar-heated water.
How do we get max efficiency in storage vs. back-up? Any suggestions out there?