This is the question that I have asked myself for sometime now. As I see it I have two options. First some household background information. There is myself and my wife. I have two young children. Now whatever I do I cannot let the wife shower in the cold. Next, the system must be sized for when the kids get older. With that, the system should have a design life of at least 15 years, more is better.

Option 1: Drainback Solar Hot Water System.

The basic components for a Solar Hot Water System are:

1) Storage Tank
2) Heat Exchanger
3) Controller
4) Solar Hot Water Panels

Solar Components can be found here.

Option 2: Hot Water Heat Pump.

The basic components for a Hot Water Heat Pump are:

1) Storage tank
2) Hot Water Heat Pump

Hot water heat pumps made by AirGenerate

Option 1 cost and considerations:

Cost for system components – $4400 for everthing
Installation – Free if DIY – estimate $800 for someone else.
Total with installation $5200. Less the tax credit of $1650
Grand total of $3550.
Now for the unknown. Annual operating cost. $25?
Assuming the tanks last 15 years. (maybe?) the total project cost would be. $3925

Considerations – Panels are usually mounted on the house and subject to storm damage.

Option 2 costs and considerations.

Cost for 80 gallon tank and hot water heat pump – $1500
Installation – Free if DIY – estimate $300 for someone else.
Total with installation $1800. Less the tax credit of $300
Grand total of $1500.
Annual operating cost. $200
Assuming the tanks last 15 years. (maybe?) the total project cost would be. $4500

Considerations – Noise from the unit while in operation.

The Solar system saves you $575 over the 15 year life. From my calculations, solar hot water may make sense for me.

For the ACEEE analysis of water heating look here.

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