What about heat recovery units instead of a Solar Hot Water Heater?

Testing by Indiana Utility Companies and the State Energy Center reveal that heat recovery only saves about $39 to $69 a year - only 1/10 of the savings of solar energy systems. First, a heat recovery unit does not save any money when you are not heating or cooling. It saves the most money when you are air conditioning, because during this time the heat pump or air conditioner has free heat to expel. However, in the winter when a heat pump must pump heat into the house from the outdoors, there will only be minimal water heating savings. In addition, heat recovery units can have problems with freezing during the winter and scaling on the heat transfer equipment - this reduces the efficiency of the unit. A heat recovery unit also might require a whole house water softener to correct the scaling problem. A water softener isn't needed for a solar system. And, a solar system, unlike heat recovery, can be connected to all household water heaters.