Solar water heaters use free energy – the Sun – to heat domestic water for homes. They can be used in any climate, and are a viable solution for anyone who wants to live off-grid or cut fuel bills. According to the U.S. Department of Energy, the average amount of money a household spends each year on water heating is $400 to $600, and accounts to 14% – 18% of total utility bills. Many homeowners use a solar system as a primary water heater and keep their gas or electric water heater as back-up.
A solar water heater can save the average household $2,900 to $5,200 over the lifetime of the appliance. The average life expectancy of a solar water heater is 20 years. As a bonus, according to Energy Star, an Energy Star certified solar water heater can cut carbon dioxide emissions in half, and prevent 4,000 pounds of carbon dioxide from entering the atmosphere annually.
There are two types of solar water heating systems: passive, which have no pump, and active, which have circulating pumps and controls. Both systems use collectors, either a flat-plate collector or an Integral collector to absorb heat before sending it on to a storage tank or tanks.
Passive systems should be installed by professionals. The system is installed in the attic. A batch collector and an insulated storage tank are installed in certain locations so that water will flow to the right area. In a Thermosyphon system water flows through as warm water rises and cooler water sinks. The collector must be installed below the storage tank so the warm water will rise into the tank.
Active systems work by pumping a heat – transfer fluid in the collectors and heat exchanger. This in turn heats the water. The fluid used won’t freeze, so this type of indirect circulation system is the type that must be used in areas that freeze. Direct circulation systems work by circulating household water through collectors and throughout the home. This type of system can only be used in areas that do not freeze.
Homeowners should work with a professional solar systems contractor who can suggest the right size and type of solar water heater that is best, and find the best location. An evaluation should be completed to see if a viable location exists and if the cost for the materials and installation warrants the expense. City building codes should be checked as well.
Expect to have infrequent maintenance on a solar water heating system, usually every three to five years. Electrical parts (if any) will need replacement at some point as well.