said by ncbill:Why not solar instead? You are in Florida.
I have had solar hot water, when it functions, its great, when something goes wrong it can be significant damage or have a significant cost to repair.
I've had a collect fail and once freeze ( yup even in Florida ) due to the controller being issue.
Putting holes in your roof for both mounting and larger ones for pluming, can lead to a path for water damage , a failed panel can dump a large amount of water into ones ceiling
My personal choice, having done the solar route, is cheap and simple, the cost savings for me would take decades to even break even on a Geo unit or solar.
A 30 dollar extra insulation blanket is the best solution for cost savings in Florida, the thermal losses on conventional HW tanks are pretty low as 3/4 of the year its warm and hot!, our electric rate are very reasonable as well.