Energy Trust Home > Renewable Energy > Solar > Water Heating > How Does Solar Work? > What happens to my water heater?
Solar water heaters are always installed with a backup heating source to ensure that hot water is available at all times. Usually, this backup is your existing water heater. However, if you are considering replacing your old water heater or installing a solar as part of a new construction project, you may want to consider other options.
Tankless, “on-demand” water heaters heat water directly without the use of a storage tank, avoiding the standby heat losses associated with conventional water heaters. When a hot water tap is turned on, cold water travels through a pipe into the unit. Either a gas burner or an electric element heats the water. Thermostatically controlled tankless heaters are designed to react to incoming water of varying temperatures. When paired with a solar water heating system, these on-demand water heaters only have to use a little energy, if any at all, to increase the solar preheated water to the desired set point.
Energy Trust provides cash incentives for tankless water heaters that meet certain efficiency requirements For eligibility information, visit out water heater pages. For more information on the Oregon State energy tax credits available for tankless water heaters, go to Oregon Department of Energy’s website.
120 Gallon Single Tank Systems
Another option is single, large-capacity tank that acts as your solar pre-heat and backup. The solar preheated water occupies the bottom half of the tank and the top contains an electric heating element to provide backup heat. Energy Trust requires 40 gallons of backup hot water and at least 80 gallons of solar storage space. Thus, a combined tank will be at least 120 gallons. Combined tank solar systems can save you money and space.
Even if you aren’t going to buy a new water heater, you can save a lot of energy and money with your existing system by following a few simple suggestions.
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Insulate Your Exisiting Water Heater: Installing an insulating jacket on your existing water heater is one of the most effective do-it-yourself energy-saving projects, especially if your water heater is in an unheated basement or space. Insulation jackets are widely available for around $10 and will reduce standby heat loss—heat lost through the walls of the tank—by 25 to 40%, saving 4 to 9% on your water heating bills. Always follow directions carefully when installing an insulation jacket. With conventional gas water heaters, be careful not to restrict the air inlet(s) at the bottom or the draft hood at the top..
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Lower the Water Heater Temperature: Keep your water heater thermostat set at the lowest temperature that provides you with sufficient hot water. Each 10°F reduction in water temperature will generally save 3–5% on your water heating costs.
- Conserve Water: Your biggest opportunity for savings is to use less hot water. In addition to saving energy and money, cutting down on hot water use helps conserve water supplies. A family of four each showering five minutes a day can use about 700 gallons per week—a three-year drinking water supply for one person! Water-conserving showerheads and faucet aerators can save that family of four 14,000 gallons of water a year and the energy required to heat it.
Energy Trust provides rebates for efficient water heaters! To learn more ways to save energy and money, visit our Home Energy Solutions program.
For more information, questions or comments, contact the solar team.