Solar Water Heating

Solar collectors can work anywhere, including the northeastern United States.

General Information

• Solar water heating, also called solar thermal heating, takes advantage of the sun's energy to pre-heat water for a number of applications including water and space heating, ventilation, cooking and kitchen operations, steam, and cooling and refrigeration.
• There are many types of solar heating systems depending on the size of the facility, available sun, heating and hot water requirements, etc.
• Solar water heating is generally one part of a larger system, serving to reduce the demand for other methods of heating water. The total system still requires backup from boilers or electric hot water heaters.

Site Considerations

• Do you have a southern exposure? Whether the system is ground, pole or roof mounted, you will get the most production from an array that faces true south. In the Boston area, that's about -15° from magnetic south or 165° on a standard compass. The further you are from south, the lower your production will be.
• Is the roof shade-free all day long? While evacuated tubes are not as affected by shade as PV panels, it is still important to have a shade-free location. Be sure to consider nearby trees, buildings, telephone poles, telephone wires, etc.
• How much productive roof space is available?
• Is your water heating load fairly consistent day-to-day and season to season?
• What are your objectives? How much load do you want to offset? Is it important that you fix your energy costs? Reduce GHG emissions? Gain some energy independence? And what are you willing to spend?

Typical Costs

• Solar process heating is a cost effective renewable energy system.
• The U.S. DOE has developed an on-line calculator to estimate your system cost: http://apps1.eere.energy.gov/consumer/your_home/water_heating/index.cfm/mytopic=12910
• Some gas utilities offer rebates on solar heating systems.
• To look up local, state and federal incentives, go http://www.dsireusa.org/
• Payback periods are generally in the 4-8 year range before incentives and tax credits (3-5 years after rebates).
• Collectors generally come with warranties of 10 years or more, and, like most renewable energy equipment, should last decades longer.

RPM can help determine if solar water heating is the right choice for your site given your heating and cooling loads, heating fuel, location and other factors.

Remember: Efficiency first. Renewables second.

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