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Solar Water Heating Economics

Free hot water even in the winter?

The tilt and size of the system will determine how your system performs in the winter. Typically the make-up water that fills the existing hot water heating is ground or city water entering at about 50F. With a Solar System this water is now pre-heated before it enters your existing water heater. This will reduce the amount of time your heater is active and this is all free hot water!

When the Solar Tank Temperature is:   Percent of free hot water generated is:
120F or more   100%
110F   86%
100F   71%
90F   57%
80F   43%
70F   29%
60F   14%
50F   0%

How does an investment that pays out 15-35% sound? Too good to be true? It's here Solar Hot Water. A properly designed and installed system can have an IRR of upwards of 30%.

Potential Uses:
Domestic Hot Water Heating -Typically for showers, laundry, dishwashers, sinks.
Radiant Heating - space heating for living area or storage area
Pool Heating - for indoor pools or outdoor pools to extend the season.
Ice Melting - Heating driveways and walkways

Case Study:

Water heating represents a substantial portion of energy use at many residential, commercial, institutional, and federal facilities. Approximately 18% of the total energy use in residential buildings and 4% in commercial buildings is for water heating. A solar water heating system, which uses the sun's energy rather than electricity or gas to heat water, can efficiently provide greater than 50% of the hot water needs, without fuel or pollution and with the added benefit of minimal operation and maintenance expense.

Heating fuel type - Diesel (#2 oil) - gal
Specific yield of Solar System kWh/m² 919
Solar fraction % 68%
Load type   Motel
Number of units Rooms 25
Initial Costs - Total   $9,901
Incentives/Grants   $4,635
Simple Payback yr 2.9
Net GHG emission reduction tCO2/yr 7.4

These are the highlights for the calculation for a motel located in New York. As this typical example illustrates, in many cases the payback period is well under 5yrs.