On Dec 16, 3:30*pm, infiniteMPG wrote:
You need pro advise , maybe alt.energy.homepower *I would be thinking to not heat the tank but use it for solar storage, if its near hot enough a cheap small electric 20-30a *tankless would be far more efficent, for single use it probably would be all you need.

Looked at the tankless but are they not more for point of use then
whole house? *And the ones that are whole house cost more then the 80
gallon lifetime tank.

but what about a cloudy week or month.

In west central Florida near the coast and it's rare to have a couple
days without enough sunlight to get hot water. *And the Gray Box
cranks on the electric heater just before dawn so the morning shower
is never cold, even with cloudly/stormy days. *:O)

Kind of brings up another question. *If you have a hot water heater
and (for this example) NO solar, if you turn the heater off for most
part of the day and then on in time to heat water for an evening
shower, does it cost more to heat a cool or cold tank of water then it
would to just maintain it all hot all day long???? *Kind of like that
old AC question, better to leave it on all the time rather then try to
cool and hot house when you get home?

There are small electric 15-30a units I have used many times, a friend
had one to heat a sink in his garage, flow was good and water hot.
You have to do temp measurements of what is avalaible with only sun
and after shade with tank off for a few days to realy know what btu is
needed, it would be flow and temperatures over a few days. I can say I
went from electric high insulated tank to a 460$ 117000 btu Bosch Ng
tankless, that cut my electric bill maybe 30 -35$ and only increased
gas maybe 7$ so I have a 4 yr payback on Ng Tankless. Ng, Propane, or
electric is the cheapest option to operate, small electric may work
fine if tank temp is high enough. It depends on how hot you want HW, I
only need 96f at the showerhead in summer and maybe100 in winter to
shower or 110 out of the tank, if the solar doesnt go below 70f
something very small would work. You need to talk to people that use
solar and explore options. A whole house electric that heats s single
ufe from near 40f incomming water would require maybe 200 amps on its
own, but a small unit might only need 20-30a if your solar set up had
enough reserve. Then there are cheap Ng and propane tankless, the
cheapest might now be 500$ not intalled