Solar Water Heaters

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Introduction

Although solar water heating systems usually have a higher up-front cost than conventional water heating systems, they can usually save you money in the long run. In addition, because the sun is free, you're protected from future fuel shortages and price hikes.

Right now, take advantage of the Federal Income Tax Credit for solar water heaters. Tax credits are available at 30% of the cost of your solar water heating system with no upper limit through 2016 for both new and existing homes.

Technology Options

Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active systems, which have circulating pumps and controls, and passive systems, which don't. Passive solar water heating systems are typically less expensive than active systems, but they are usually not as efficient. However, passive systems can be more reliable and may last longer.

Among active systems, two types of circulation are available. Direct circulation systems circulate household water through the collectors and into the home. They work well in climates where it rarely freezes. Indirect circulation systems circulate a non-freezing, heat-transfer fluid through the collectors and a heat exchanger. This heats the water that then flows into the home. They are popular in climates prone to freezing temperatures.

Most solar water heaters require a well-insulated storage tank. In two-tank systems, the solar water heater preheats water before it enters the conventional water heater. In one-tank systems, the back-up heater is combined with the solar storage in one tank.

Three types of solar collectors are used for residential applications: Flat-plate collectors, integral collector-storage systems and evacuated-tube solar collectors. More information on each of these types is available on the Department of Energy website.

Solar water heating systems almost always require a backup system for cloudy days and times of increased demand. Conventional storage water heaters usually provide backup and may already be part of the solar system package. A backup system may also be part of the solar collector, such as rooftop tanks. Since an integral-collector storage system already stores hot water in addition to collecting solar heat, it may be packaged with a demand (tankless or instantaneous) water heater for backup.

Efficiency Benefits

On average, if you install a solar water heater, your water heating bills should drop 50%–80%.

How much money you save depends on the following:
  • The amount of hot water you use.
  • Your system's performance.
  • How sunny your site is.
  • Available financing and incentives.
  • The cost of conventional fuels (natural gas, oil, and electricity).

If you're building a new home or refinancing, you may see savings immediately. The price of a solar water heater in a new 30-year mortgage is typically about $13 to $20 more per month minus the federal income tax deduction for mortgage interest on solar systems, which is about $3–$5 per month. So if your fuel savings are more than $15 per month, the solar investment is profitable immediately.

Manufacturers

Solar Direct, Apricus, and Heliodyne are some of the major distributors of solar water heaters.

Purchasing Tips

Before you buy a solar water heating system, consider doing the following:
  • Investigate the economics of a solar water heating system: Determine the energy savings and payback period of investing in a more energy-efficient system versus a less efficient system, which is typically cheaper up-front, but more expensive to operate. Remember to take advantage of the Federal Income Tax Credit for solar water heaters.
  • Check to be sure your site is sunny enough.
  • Determine the correct system size and type.
  • Check local codes, covenants, and regulations that could affect your installation.